High prevalence of asymptomatic Plasmodium falciparum infection in Gabonese adults.

PubMed

Dal-Bianco, Matthias P; Köster, Kai B; Kombila, Ulrich D; Kun, Jürgen F J; Grobusch, Martin P; Ngoma, Ghyslain Mombo; Matsiegui, Pierre B; Supan, Christian; Salazar, Carmen L Ospina; Missinou, Michel A; Issifou, Saadou; Lell, Bertrand; Kremsner, Peter

2007-11-01

Plasmodium falciparum, the most common malarial parasite in sub-Saharan Africa, accounts for a high number of deaths in children less than five years of age. In malaria-endemic countries with stable transmission, semi-immunity is usually acquired after childhood. For adults, severe malaria is rare. Infected adults have either uncomplicated malaria or asymptomatic parasitemia. During a period of one year, we screened 497 afebrile males to investigate the prevalence of asymptomatic P. falciparum parasitemia in villages near Lambaréné, Gabon by use of three different methods. A total of 52% of the individuals had parasites detected by a subtelomeric variable open reading frame polymerase chain reaction (stevor-PCR), 27% of the rapid diagnostic test results were positive, and 12% of the thick blood smears with low parasitemias had P. falciparum. Most positive cases were only detected by the stevor-PCR. Asymptomatic P. falciparum parasitemia in adults living in a malaria-endemic country is frequent.

The neurological assessment in young children treated with artesunate monotherapy or artesunate-mefloquine combination therapy for uncomplicated Plasmodium falciparum malaria.

PubMed

Ambler, Michael T; Dubowitz, Lilly M; Arunjerdja, Ratree; Hla, Eh Paw; Thwai, Kyaw Lay; Viladpainguen, Jacher; Singhasivanon, Pratap; Luxemburger, Christine; Nosten, François; McGready, Rose

2009-09-02

Mefloquine and artesunate combination therapy is the recommended first-line treatment for uncomplicated malaria throughout much of south-east Asia. Concerns have been raised about the potential central nervous system (CNS) effects of both drug components and there are no detailed reports in very young children. Children, aged between three months and five years, with acute uncomplicated Plasmodium falciparum malaria were randomized to either 7 days of artesunate monotherapy or the same schedule of artesunate plus mefloquine on day 7 and 8. Neurological testing targeting coordination and behaviour was carried out at day 0, 7, 9, 10, 14 and 28. Non-febrile healthy control children from the same population were tested on days 0, 7, 14 and 28. From December 1994 to July 1997, 91 children with uncomplicated P. falciparum, 45 treated with artesunate monotherapy, 46 treated with mefloquine and artesunate combination therapy and 36 non-febrile controls, underwent neurological testing. Malaria and fever had a significant negative impact on testing performance. By contrast, the anti-malarial treatments were not associated with worsening performances in the various components of the test. Artesunate and mefloquine do not appear to have a significant influence on coordination and behaviour. Children treated with mefloquine were significantly less likely to suffer recurrent malaria infection during follow-up compared to those treated with artesunate alone (P = 0.033). In keeping with the results of randomized controlled trials in adults, mefloquine was not associated with a decrease in specific items of neurological performance. Likewise, children treated with artesunate did not perform significantly differently to control children. This study does not exclude subtle or rare treatment CNS effects of artesunate or mefloquine. Treatment of acute uncomplicated malaria results in a significant improvement on items of neurological performance.

Preserved dendritic cell HLA-DR expression and reduced regulatory T cell activation in asymptomatic Plasmodium falciparum and P. vivax infection.

PubMed

Kho, Steven; Marfurt, Jutta; Noviyanti, Rintis; Kusuma, Andreas; Piera, Kim A; Burdam, Faustina H; Kenangalem, Enny; Lampah, Daniel A; Engwerda, Christian R; Poespoprodjo, Jeanne R; Price, Ric N; Anstey, Nicholas M; Minigo, Gabriela; Woodberry, Tonia

2015-08-01

Clinical illness with Plasmodium falciparum or Plasmodium vivax compromises the function of dendritic cells (DC) and expands regulatory T (Treg) cells. Individuals with asymptomatic parasitemia have clinical immunity, restricting parasite expansion and preventing clinical disease. The role of DC and Treg cells during asymptomatic Plasmodium infection is unclear. During a cross-sectional household survey in Papua, Indonesia, we examined the number and activation of blood plasmacytoid DC (pDC), CD141(+), and CD1c(+) myeloid DC (mDC) subsets and Treg cells using flow cytometry in 168 afebrile children (of whom 15 had P. falciparum and 36 had P. vivax infections) and 162 afebrile adults (of whom 20 had P. falciparum and 20 had P. vivax infections), alongside samples from 16 patients hospitalized with uncomplicated malaria. Unlike DC from malaria patients, DC from children and adults with asymptomatic, microscopy-positive P. vivax or P. falciparum infection increased or retained HLA-DR expression. Treg cells in asymptomatic adults and children exhibited reduced activation, suggesting increased immune responsiveness. The pDC and mDC subsets varied according to clinical immunity (asymptomatic or symptomatic Plasmodium infection) and, in asymptomatic infection, according to host age and parasite species. In conclusion, active control of asymptomatic infection was associated with and likely contingent upon functional DC and reduced Treg cell activation. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

No Clinical or Molecular Evidence of Plasmodium falciparum Resistance to Artesunate–Mefloquine in Northwestern Brazil

PubMed Central

Ladeia-Andrade, Simone; de Melo, Gladson Naber P.; de Souza-Lima, Rita de Cássia; Salla, Laís C.; Bastos, Melissa S.; Rodrigues, Priscila T.; Luz, Francisco das Chagas O.; Ferreira, Marcelo U.

2016-01-01

We evaluated the clinical efficacy of artesunate–mefloquine (ASMQ) fixed-dose combination to treat uncomplicated malaria in Juruá Valley, the main Plasmodium falciparum transmission hotspot in Brazil. Between November 2010 and February 2013, we enrolled 162 patients aged 4–73 years, with fever or a history of fever, and a single-species P. falciparum infection confirmed by microscopy and polymerase chain reaction (PCR). All 154 patients who completed the 42-day follow-up presented an adequate clinical and parasitologic response. ASMQ was well tolerated and no adverse event caused treatment interruption. Gametocytes were detected in 46.3% patients; 35.2% had gametocytes at enrollment, whereas others developed patent gametocytemia 1–14 days after starting ASMQ. By day 3 of treatment, all subjects had cleared asexual parasitemia, but parasite DNA remained PCR detectable in 37.6% of them. Day-3 PCR positivity was associated with prolonged gametocyte carriage. We found no molecular evidence of resistance to either MQ (pfmdr1 gene amplification) or AS (mutations in selected kelch13 gene domains known to be associated with AS resistance) in the local P. falciparum population. These results strongly support the use of ASMQ as a first-line regimen to treat uncomplicated P. falciparum malaria in northwestern Brazil, but underscore the need for gametocytocidal drugs to reduce the transmission potential of ASMQ-treated patients (ClinicalTrials.gov number NCT01144702). PMID:27068396

K13 Propeller Alleles, mdr1 Polymorphism, and Drug Effectiveness at Day 3 after Artemether-Lumefantrine Treatment for Plasmodium falciparum Malaria in Colombia, 2014-2015.

PubMed

Montenegro, Madeline; Neal, Aaron T; Posada, Maritza; De Las Salas, Briegel; Lopera-Mesa, Tatiana M; Fairhurst, Rick M; Tobon-Castaño, Alberto

2017-12-01

High treatment failure rates for Plasmodium falciparum malaria have been reported in Colombia for chloroquine, amodiaquine, and sulfadoxine-pyrimethamine. Artemisinin combination therapies were introduced in 2006 in Colombia, where artemether-lumefantrine (AL) is currently used to treat uncomplicated P. falciparum malaria. Artemisinin (ART) resistance was initially observed in Southeast Asia as an increased parasite clearance time, manifesting as a positive thick-blood smear on day 3 after treatment (D3 positivity). Recently, mutations in the propeller domain of the P. falciparum kelch13 gene ( K13 propeller) have been associated with ART resistance. In this study, we surveyed AL effectiveness at D3 and molecular markers of drug resistance among 187 uncomplicated P. falciparum cases in 4 regions of Colombia from June 2014 to July 2015. We found that 3.2% (4/125) of patients showed D3 positivity, 100% (163/163) of isolates carried wild-type K13 propeller alleles, 12.9% (23/178) of isolates had multiple copies of the multidrug resistance 1 gene ( mdr1 ), and 75.8% (113/149) of isolates harbored the double mutant N F S D D mdr1 haplotype (the underlining indicates mutant alleles). These data suggest that ART resistance is not currently suspected in Colombia but that monitoring for lumefantrine resistance and AL failures should continue. Copyright © 2017 American Society for Microbiology.

K13 Propeller Alleles, mdr1 Polymorphism, and Drug Effectiveness at Day 3 after Artemether-Lumefantrine Treatment for Plasmodium falciparum Malaria in Colombia, 2014-2015

PubMed Central

Montenegro, Madeline; Neal, Aaron T.; Posada, Maritza; De las Salas, Briegel; Lopera-Mesa, Tatiana M.

2017-01-01

ABSTRACT High treatment failure rates for Plasmodium falciparum malaria have been reported in Colombia for chloroquine, amodiaquine, and sulfadoxine-pyrimethamine. Artemisinin combination therapies were introduced in 2006 in Colombia, where artemether-lumefantrine (AL) is currently used to treat uncomplicated P. falciparum malaria. Artemisinin (ART) resistance was initially observed in Southeast Asia as an increased parasite clearance time, manifesting as a positive thick-blood smear on day 3 after treatment (D3 positivity). Recently, mutations in the propeller domain of the P. falciparum kelch13 gene (K13 propeller) have been associated with ART resistance. In this study, we surveyed AL effectiveness at D3 and molecular markers of drug resistance among 187 uncomplicated P. falciparum cases in 4 regions of Colombia from June 2014 to July 2015. We found that 3.2% (4/125) of patients showed D3 positivity, 100% (163/163) of isolates carried wild-type K13 propeller alleles, 12.9% (23/178) of isolates had multiple copies of the multidrug resistance 1 gene (mdr1), and 75.8% (113/149) of isolates harbored the double mutant NFSDD mdr1 haplotype (the underlining indicates mutant alleles). These data suggest that ART resistance is not currently suspected in Colombia but that monitoring for lumefantrine resistance and AL failures should continue. PMID:28947476

Alterations in cytokines and haematological parameters during the acute and convalescent phases of Plasmodium falciparum and Plasmodium vivax infections.

PubMed

Rodrigues-da-Silva, Rodrigo Nunes; Lima-Junior, Josué da Costa; Fonseca, Bruna de Paula Fonseca e; Antas, Paulo Renato Zuquim; Baldez, Arlete; Storer, Fabio Luiz; Santos, Fátima; Banic, Dalma Maria; Oliveira-Ferreira, Joseli de

2014-04-01

Haematological and cytokine alterations in malaria are a broad and controversial subject in the literature. However, few studies have simultaneously evaluated various cytokines in a single patient group during the acute and convalescent phases of infection. The aim of this study was to sequentially characterise alterations in haematological patters and circulating plasma cytokine and chemokine levels in patients infected with Plasmodium vivax or Plasmodium falciparum from a Brazilian endemic area during the acute and convalescent phases of infection. During the acute phase, thrombocytopaenia, eosinopaenia, lymphopaenia and an increased number of band cells were observed in the majority of the patients. During the convalescent phase, the haematologic parameters returned to normal. During the acute phase, P. vivax and P. falciparum patients had significantly higher interleukin (IL)-6, IL-8, IL-17, interferon-γ, tumour necrosis factor (TNF)-α, macrophage inflammatory protein-1β and granulocyte-colony stimulating factor levels than controls and maintained high levels during the convalescent phase. IL-10 was detected at high concentrations during the acute phase, but returned to normal levels during the convalescent phase. Plasma IL-10 concentration was positively correlated with parasitaemia in P. vivax and P. falciparum-infected patients. The same was true for the TNF-α concentration in P. falciparum-infected patients. Finally, the haematological and cytokine profiles were similar between uncomplicated P. falciparum and P. vivax infections.

Glucose-6-phosphate dehydrogenase status and risk of hemolysis in Plasmodium falciparum-infected African children receiving single-dose primaquine.

PubMed

Eziefula, Alice C; Pett, Helmi; Grignard, Lynn; Opus, Salome; Kiggundu, Moses; Kamya, Moses R; Yeung, Shunmay; Staedke, Sarah G; Bousema, Teun; Drakeley, Chris

2014-08-01

Glucose-6-phosphate dehydrogenase (G6PD) enzyme function and genotype were determined in Ugandan children with uncomplicated falciparum malaria enrolled in a primaquine trial after exclusion of severe G6PD deficiency by fluorescent spot test. G6PD A- heterozygotes and hemizygotes/homozygotes experienced dose-dependent lower hemoglobin concentrations after treatment. No severe anemia was observed. Copyright © 2014, Eziefula et al.

Short report: polymorphisms in the chloroquine resistance transporter gene in Plasmodium falciparum isolates from Lombok, Indonesia.

PubMed

Huaman, Maria Cecilia; Yoshinaga, Kazumi; Suryanatha, Aan; Suarsana, Nyoman; Kanbara, Hiroji

2004-07-01

The polymorphisms in the Plasmodium falciparum multidrug resistance 1 (pfmdr1) and P. falciparum chloroquine resistance transporter (pfcrt) genes, which are associated with chloroquine resistance, were examined in 48 P. falciparum isolates from uncomplicated malaria patients from the West Lombok District in Indonesia. The point mutation N86Y in pfmdr1 was present in 35.4% of the isolates and mutation K76T in pfcrt was found in all but one of the samples studied. Identified pfcrt haplotypes were mainly identical to the Papua New Guinea type S(agt)VMNT (42 of 48, 87.5%), and a few isolates had the Southeast Asia type CVIET (5 of 48, 10.4%). Moreover, one P. falciparum isolate harbored the K76N mutation, giving rise to the haplotype CVMNN, which was not previously reported in field isolates. Our findings suggest that chloroquine resistance in this area might have the same origin as in Papua New Guinea.

Assessment of the therapeutic efficacy of artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal: an observational cohort study.

PubMed

Vaughan-Williams, Charles H; Raman, Jaishree; Raswiswi, Eric; Immelman, Etienne; Reichel, Holger; Gate, Kelly; Knight, Steve

2012-12-28

Recent malaria epidemics in KwaZulu-Natal indicate that effective anti-malarial therapy is essential for malaria control. Although artemether-lumefantrine has been used as first-line treatment for uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal since 2001, its efficacy has not been assessed since 2002. The objectives of this study were to quantify the proportion of patients treated for uncomplicated P. falciparum malaria with artemether-lumefantrine who failed treatment after 28 days, and to determine the prevalence of molecular markers associated with artemether-lumefantrine and chloroquine resistance. An observational cohort of 49 symptomatic patients, diagnosed with uncomplicated P. falciparum malaria by rapid diagnostic test, had blood taken for malaria blood films and P. falciparum DNA polymerase chain reaction (PCR). Following diagnosis, patients were treated with artemether-lumefantrine (Coartem®) and invited to return to the health facility after 28 days for repeat blood film and PCR. All PCR P. falciparum positive samples were analysed for molecular markers of lumefantrine and chloroquine resistance. Of 49 patients recruited on the basis of a positive rapid diagnostic test, only 16 were confirmed to have P. falciparum by PCR. At follow-up, 14 were PCR-negative for malaria, one was lost to follow-up and one blood specimen had insufficient blood for a PCR analysis. All 16 with PCR-confirmed malaria carried a single copy of the multi-drug resistant (mdr1) gene, and the wild type asparagine allele mdr1 codon 86 (mdr1 86N). Ten of the 16 samples carried the wild type haplotype (CVMNK) at codons 72-76 of the chloroquine resistance transporter gene (pfcrt); three samples carried the resistant CVIET allele; one carried both the resistant and wild type, and in two samples the allele could not be analysed. The absence of mdr1 gene copy number variation detected in this study suggests lumefantrine resistance has yet to emerge in KwaZulu-Natal. In addition, data from this investigation implies the possible re-emergence of chloroquine-sensitive parasites. Results from this study must be viewed with caution, given the extremely small sample size. A larger study is needed to accurately determine therapeutic efficacy of artemether-lumefantrine and resistance marker prevalence. The high proportion of rapid diagnostic test false-positive results requires further investigation.

Platelet-mediated clumping of Plasmodium falciparum infected erythrocytes is associated with high parasitemia but not severe clinical manifestations of malaria in African children

PubMed Central

Arman, Mònica; Raza, Ahmed; Tempest, Louisa J.; Lyke, Kirsten E.; Thera, Mahamadou A.; Koné, Abdoulaye; Plowe, Christopher V.; Doumbo, Ogobara K.; Rowe, J. Alexandra

2009-01-01

Platelet-mediated clumping of Plasmodium falciparum infected erythrocytes is an adhesive phenotype commonly found in field isolates that has previously been associated with severe malaria. Here, clumping was assessed in 131 isolates from Malian children. The clumping phenotype was seen in 6% (n=51) of uncomplicated malaria, 24% (n=51) of severe malaria, and 45% (n=29) of high parasitemia non-severe malaria isolates. Multivariate analysis indicated that clumping was strongly positively associated with parasitemia (F1,122=24.1, p<0.001) but not with disease category (F2,122=1.8, p=0.17). Therefore platelet-mediated clumping in Malian P. falciparum isolates is primarily associated with high parasitemia and not with severe clinical manifestations of malaria. PMID:17984358

Artesunate-mefloquine combination therapy in acute Plasmodium falciparum malaria in young children: a field study regarding neurological and neuropsychiatric safety.

PubMed

Frey, Sarabel G; Chelo, David; Kinkela, Mina N; Djoukoue, Florence; Tietche, Felix; Hatz, Christoph; Weber, Peter

2010-10-21

Mefloquine-artesunate combination therapy for uncomplicated falciparum malaria is one of the treatments used in African children. Data concerning neurological safety in adults and children treated with mefloquine and artesunate combination therapy is well documented in Asia. Safety data for neurological and neuropsychiatric side effects of mefloquine and artesunate combination therapy in African children are scarce, although WHO recommends this therapy in Africa. A phase IV, open label, single arm study was conducted among African children between 10 and 20 kg with acute uncomplicated falciparum malaria. They were treated over three consecutive days with a paediatric fixed-dose combination of artesunate (50 mg/d) and mefloquine (125 mg/d). Parasitological, clinical and neurological examinations and standardized questions about neuropsychiatric symptoms were carried out on days 0, 4, 7, 28 and 63. The primary objective was to assess the neurological and neuropsychiatric safety of artesunate-mefloquine combination therapy in young children. From December 2007 to March 2009, 220 children with uncomplicated Plasmodium falciparum malaria were treated with artesunate and mefloquine. 213 children were analysed according to study protocol. 50 neurological and neuropsychiatric adverse events occurred in 28 patients. Eleven drug-related neurological and neuropsychiatric adverse events occurred in eight patients. Sleeping disorders were present in 2.3%, neurological disorders in 1.4%, neuropsychiatric disorders in 1% and eating disorders in 0.5% of the patients. Adverse events were of mild to moderate intensity and resolved spontaneously. African children showed a low percentage of self-limited neurological and neuropsychiatric adverse events, confirming studies on neurological safety in Asian children treated with artesunate and mefloquine. Sleeping disorders were most frequently observed.

Serum laminin in malaria.

PubMed Central

Wenisch, C; Graninger, W; Viravan, C; Looareesuwan, S; Parschalk, B; Wernsdorfer, W

1994-01-01

AIM--To determine serum laminin concentrations in patients with uncomplicated Plasmodium falciparum malaria. METHODS--An enzyme linked immunosorbent assay (ELISA) was used to determine serum laminin concentrations in 54 patients with acute uncomplicated P falciparum malaria during and after treatment, and in 17 control subjects in Bangkok, Thailand. RESULTS--Raised concentrations of soluble laminin were observed in patients (mean (SD) concentration 628 (225) ng/ml), compared with normal controls (490 (116) ng/ml), during the acute phase of the disease. During treatment, serum laminin concentrations decreased and returned to normal within three days. Serum laminin concentrations were correlated with parasite counts before treatment, and with the serum concentration of soluble intercellular adhesion molecule-1 (ICAM-1), soluble E-selectin, and soluble tumour necrosis factor receptor at 55 kilodaltons. CONCLUSIONS--These findings are compatible with an increased production or release of laminin in P falciparum malaria, which could indicate a role for the subendothelial basement membrane in the pathogenesis of the disease. PMID:7525659

Risk factors for Plasmodium falciparum and Plasmodium vivax gametocyte carriage in Papua New Guinean children with uncomplicated malaria.

PubMed

Karl, Stephan; Laman, Moses; Moore, Brioni R; Benjamin, John M; Salib, Mary; Lorry, Lina; Maripal, Samuel; Siba, Peter; Robinson, Leanne J; Mueller, Ivo; Davis, Timothy M E

2016-08-01

There are limited data on gametocytaemia risk factors before/after treatment with artemisinin combination therapy in children from areas with transmission of multiple Plasmodium species. We utilised data from a randomised trial comparing artemether-lumefantrine (AL) and artemisinin-naphthoquine (AN) in 230 Papua New Guinean children aged 0.5-5 years with uncomplicated malaria in whom determinants of gametocytaemia by light microscopy were assessed at baseline using logistic regression and during follow-up using multilevel mixed effects modelling. Seventy-four (32%) and 18 (8%) children presented with P. falciparum and P. vivax gametocytaemia, respectively. Baseline P. falciparum gametocytaemia was associated with Hackett spleen grade 1 (odds ratio (95% CI) 4.01 (1.60-10.05) vs grade 0; P<0.001) and haemoglobin (0.95 (0.92-0.97) per 1g/L increase; P<0.001), and P. falciparum asexual parasitaemia in slide-positive cases (0.36 (0.19-0.68) for a 10-fold increase; P=0.002). Baseline P. vivax gametocytaemia was associated with Hackett grade 2 (12.66 (1.31-122.56); P=0.028), mixed P. falciparum/vivax infection (0.16 (0.03-1.00); P=0.050), P. vivax asexual parasitaemia (5.68 (0.98-33.04); P=0.053) and haemoglobin (0.94 (0.88-1.00); P=0.056). For post-treatment P. falciparum gametocytaemia, independent predictors were AN vs AL treatment (4.09 (1.43-11.65)), haemoglobin (0.95 (0.93-0.97)), presence/absence of P. falciparum asexual forms (3.40 (1.66-0.68)) and day post-treatment (0.086 (0.82-0.90)) (P<0.001). Post-treatment P. vivax gametocytaemia was predicted by presence of P. vivax asexual forms (596 (12-28,433); P<0.001). Consistent with slow P. falciparum gametocyte maturation, low haemoglobin, low asexual parasite density and higher spleen grading, markers of increased prior infection exposure/immunity, were strong associates of pre-treatment gametocyte positivity. The persistent inverse association between P. falciparum gametocytaemia and haemoglobin during follow-up suggests an important role for bone marrow modulation of gametocytogenesis. In P. vivax infections, baseline and post-treatment gametocyte carriage was positively related to the acute parasite burden, reflecting the close association between the development of asexual and sexual forms. Copyright © 2016 Elsevier B.V. All rights reserved.

Drug resistance associated genetic polymorphisms in Plasmodium falciparum and Plasmodium vivax collected in Honduras, Central America.

PubMed

Jovel, Irina T; Mejía, Rosa E; Banegas, Engels; Piedade, Rita; Alger, Jackeline; Fontecha, Gustavo; Ferreira, Pedro E; Veiga, Maria I; Enamorado, Irma G; Bjorkman, Anders; Ursing, Johan

2011-12-19

In Honduras, chloroquine and primaquine are recommended and still appear to be effective for treatment of Plasmodium falciparum and Plasmodium vivax malaria. The aim of this study was to determine the proportion of resistance associated genetic polymorphisms in P. falciparum and P. vivax collected in Honduras. Blood samples were collected from patients seeking medical attention at the Hospital Escuela in Tegucigalpa from 2004 to 2006 as well as three regional hospitals, two health centres and one regional laboratory during 2009. Single nucleotide polymorphisms in P. falciparum chloroquine resistance transporter (pfcrt), multidrug resistance 1 (pfmdr1), dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes and in P. vivax multidrug resistance 1 (pvmdr1) and dihydrofolate reductase (pvdhfr) genes were detected using PCR based methods. Thirty seven P. falciparum and 64 P. vivax samples were collected. All P. falciparum infections acquired in Honduras carried pfcrt, pfmdr1, pfdhps and pfdhfr alleles associated with chloroquine, amodiaquine and sulphadoxine-pyrimethamine sensitivity only. One patient with parasites acquired on a Pacific Island had pfcrt 76 T and pfmdr1 86Y alleles. That patient and a patient infected in West Africa had pfdhfr 51I, 59 R and 108 N alleles. Pvmdr1 976 F was found in 7/37 and two copies of pvmdr1 were found in 1/37 samples. Pvdhfr 57 L + 58 R was observed in 2/57 samples. The results indicate that P. falciparum from Honduras remain sensitive to chloroquine and sulphadoxine-pyrimethamine. This suggests that chloroquine and sulphadoxine-pyrimethamine should be efficacious for treatment of uncomplicated P. falciparum malaria, supporting current national treatment guidelines. However, genetic polymorphisms associated with chloroquine and sulphadoxine-pyrimethamine tolerance were detected in local P. vivax and imported P. falciparum infections. Continuous monitoring of the prevalence of drug resistant/tolerant P. falciparum and P. vivax is therefore essential also in Honduras.

Drug resistance associated genetic polymorphisms in Plasmodium falciparum and Plasmodium vivax collected in Honduras, Central America

PubMed Central

2011-01-01

Background In Honduras, chloroquine and primaquine are recommended and still appear to be effective for treatment of Plasmodium falciparum and Plasmodium vivax malaria. The aim of this study was to determine the proportion of resistance associated genetic polymorphisms in P. falciparum and P. vivax collected in Honduras. Methods Blood samples were collected from patients seeking medical attention at the Hospital Escuela in Tegucigalpa from 2004 to 2006 as well as three regional hospitals, two health centres and one regional laboratory during 2009. Single nucleotide polymorphisms in P. falciparum chloroquine resistance transporter (pfcrt), multidrug resistance 1 (pfmdr1), dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes and in P. vivax multidrug resistance 1 (pvmdr1) and dihydrofolate reductase (pvdhfr) genes were detected using PCR based methods. Results Thirty seven P. falciparum and 64 P. vivax samples were collected. All P. falciparum infections acquired in Honduras carried pfcrt, pfmdr1, pfdhps and pfdhfr alleles associated with chloroquine, amodiaquine and sulphadoxine-pyrimethamine sensitivity only. One patient with parasites acquired on a Pacific Island had pfcrt 76 T and pfmdr1 86Y alleles. That patient and a patient infected in West Africa had pfdhfr 51I, 59 R and 108 N alleles. Pvmdr1 976 F was found in 7/37 and two copies of pvmdr1 were found in 1/37 samples. Pvdhfr 57 L + 58 R was observed in 2/57 samples. Conclusion The results indicate that P. falciparum from Honduras remain sensitive to chloroquine and sulphadoxine-pyrimethamine. This suggests that chloroquine and sulphadoxine-pyrimethamine should be efficacious for treatment of uncomplicated P. falciparum malaria, supporting current national treatment guidelines. However, genetic polymorphisms associated with chloroquine and sulphadoxine-pyrimethamine tolerance were detected in local P. vivax and imported P. falciparum infections. Continuous monitoring of the prevalence of drug resistant/tolerant P. falciparum and P. vivax is therefore essential also in Honduras. PMID:22183028

Assessment of the therapeutic efficacy of artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal: an observational cohort study

PubMed Central

2012-01-01

Background Recent malaria epidemics in KwaZulu-Natal indicate that effective anti-malarial therapy is essential for malaria control. Although artemether-lumefantrine has been used as first-line treatment for uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal since 2001, its efficacy has not been assessed since 2002. The objectives of this study were to quantify the proportion of patients treated for uncomplicated P. falciparum malaria with artemether-lumefantrine who failed treatment after 28 days, and to determine the prevalence of molecular markers associated with artemether-lumefantrine and chloroquine resistance. Methods An observational cohort of 49 symptomatic patients, diagnosed with uncomplicated P. falciparum malaria by rapid diagnostic test, had blood taken for malaria blood films and P. falciparum DNA polymerase chain reaction (PCR). Following diagnosis, patients were treated with artemether-lumefantrine (Coartem®) and invited to return to the health facility after 28 days for repeat blood film and PCR. All PCR P. falciparum positive samples were analysed for molecular markers of lumefantrine and chloroquine resistance. Results Of 49 patients recruited on the basis of a positive rapid diagnostic test, only 16 were confirmed to have P. falciparum by PCR. At follow-up, 14 were PCR-negative for malaria, one was lost to follow-up and one blood specimen had insufficient blood for a PCR analysis. All 16 with PCR-confirmed malaria carried a single copy of the multi-drug resistant (mdr1) gene, and the wild type asparagine allele mdr1 codon 86 (mdr1 86N). Ten of the 16 samples carried the wild type haplotype (CVMNK) at codons 72-76 of the chloroquine resistance transporter gene (pfcrt); three samples carried the resistant CVIET allele; one carried both the resistant and wild type, and in two samples the allele could not be analysed. Conclusions The absence of mdr1 gene copy number variation detected in this study suggests lumefantrine resistance has yet to emerge in KwaZulu-Natal. In addition, data from this investigation implies the possible re-emergence of chloroquine-sensitive parasites. Results from this study must be viewed with caution, given the extremely small sample size. A larger study is needed to accurately determine therapeutic efficacy of artemether-lumefantrine and resistance marker prevalence. The high proportion of rapid diagnostic test false-positive results requires further investigation. PMID:23272998

Efficacy and safety of artemisinin combination therapy (ACT) for non-falciparum malaria: a systematic review.

PubMed

Visser, Benjamin J; Wieten, Rosanne W; Kroon, Daniëlle; Nagel, Ingeborg M; Bélard, Sabine; van Vugt, Michèle; Grobusch, Martin P

2014-11-26

Artemisinin combination therapy (ACT) is recommended as first-line treatment for uncomplicated Plasmodium falciparum malaria, whereas chloroquine is still commonly used for the treatment of non-falciparum species (Plasmodium vivax, Plasmodium ovale and Plasmodium malariae). A more simplified, more uniform treatment approach across all malaria species is worthwhile to be considered both in endemic areas and for malaria as an imported condition alike. A PROSPERO-registered systematic review to determine the efficacy and safety of ACT for the treatment of non-falciparum malaria was conducted, following PRISMA guidelines. Without language restrictions, Medline/PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, Biosis Previews and the African Index Medicus were searched for studies published up to November 2014. The literature search identified 986 reports; 40 publications were found eligible for inclusion, all of them on non-falciparum malaria in endemic areas. Most evidence was available for P. vivax (n = 35). Five clinical trials in total were identified evaluating ACT for P. ovale, P. malariae and Plasmodium knowlesi. Most ACT presentations have high efficacy against P. vivax parasites; artemisinin-based combinations have shorter parasite and fever clearance times compared to chloroquine. ACT is as effective as chloroquine in preventing recurrent parasitaemia before day 28. Artemisinin-based combinations with long half-lives show significantly fewer recurrent parasitaemia up to day 63. The limited evidence available supports both the use of chloroquine and an ACT for P. ovale and P. malariae. ACT seems to be preferable for optimal treatment of P. knowlesi. ACT is at least equivalent to chloroquine in effectively treating non-falciparum malaria. These findings may facilitate development of simplified protocols for treating all forms of malaria with ACT, including returning travellers. Obtaining comprehensive efficacy and safety data on ACT use for non-falciparum species particularly for P. ovale, P. malariae and P. knowlesi should be a research priority. CRD42014009103.

Detection of Plasmodium knowlesi, Plasmodium falciparum and Plasmodium vivax using loop-mediated isothermal amplification (LAMP) in a co-endemic area in Malaysia.

PubMed

Piera, Kim A; Aziz, Ammar; William, Timothy; Bell, David; González, Iveth J; Barber, Bridget E; Anstey, Nicholas M; Grigg, Matthew J

2017-01-13

Plasmodium knowlesi is the most common cause of malaria in Malaysia. However, microscopic diagnosis is inaccurate and rapid diagnostic tests (RDTs) are insufficiently sensitive. PCR is sensitive and specific but not feasible at a district level. Loop-mediated isothermal amplification (LAMP) shows potential with only basic requirements. A commercially available LAMP assay, the Eiken Loopamp™ MALARIA Pan Detection kit, is sensitive for Plasmodium falciparum and Plasmodium vivax, but has not previously been evaluated for P. knowlesi. This study aims to determine the sensitivity of this LAMP assay for detecting P. knowlesi infection. Study participants included 73 uncomplicated malaria patients with PCR species confirmation: 50 P. knowlesi, 20 P. falciparum and 3 P. vivax. Nineteen malaria-negative, non-endemic area controls were also included. The sensitivity of the Eiken Loopamp™ MALARIA Pan Detection kit (Pan LAMP) for detecting each Plasmodium species was evaluated. Sensitivity and specificity of the Eiken Loopamp™ MALARIA Pf Detection kit (Pf LAMP) for P. falciparum were also determined. The limit of detection for each LAMP assay was evaluated, with results compared to PCR. All P. knowlesi patients were also tested by CareStart™ (Pf/VOM) and OptiMAL-IT™ (Pan/Pf) RDTs. The sensitivity of the Pan LAMP assay was 100% for P. knowlesi (95% CI 92.9-100), P. falciparum (95% CI 83.2-100), and P. vivax (95% CI 29.2-100). The Pf LAMP was 100% sensitive and specific for P. falciparum detection, with all P. knowlesi samples having a negative reaction. LAMP sensitivity was superior to both RDTs, with only 10 and 28% of P. knowlesi samples testing positive to CareStart™ and OptiMAL-IT™, respectively. Limit of detection using the Pan LAMP for both P. knowlesi and P. vivax was 2 parasites/μL, comparable to PCR. For P. falciparum both the Pan LAMP and Pf LAMP demonstrated a limit of detection of 20 parasites/μL. The Eiken Loopamp™ MALARIA Pan Detection kit is sensitive for detection of P. knowlesi in low parasitaemia clinical infections, as well as P. falciparum and P. vivax. However, a P. knowlesi-specific field assay in a simpler format would assist correct species identification and initiation of optimal treatment for all malaria patients.

Plasmodium falciparum clearance with artemisinin-based combination therapy (ACT) in patients with glucose-6-phosphate dehydrogenase deficiency in Mali.

PubMed

Kone, Abdoulaye K; Sagara, Issaka; Thera, Mahamadou A; Dicko, Alassane; Guindo, Aldiouma; Diakite, Seidina; Kurantsin-Mills, Joseph; Djimde, Abdoulaye; Walcourt, Asikiya; Doumbo, Ogabara

2010-11-21

Artemisinin-based combination therapy (ACT) is currently the most effective medicine for the treatment of uncomplicated malaria. Artemisinin has previously been shown to increase the clearance of Plasmodium falciparum in malaria patients with haemoglobin E trait, but it did not increase parasite inhibition in an in vitro study using haemoglobin AS erythrocytes. The current study describes the efficacy of artemisinin derivatives on P. falciparum clearance in patients with glucose-6-phosphate dehydrogenase deficiency (G6PD), a haemoglobin enzyme deficiency, not yet studied in the same context, but nonetheless is a common in malaria endemic areas, associated with host protection against uncomplicated and severe malaria. The impact of G6PD deficiency on parasite clearance with ACT treatment was compared between G6PD-deficient patients and G6PD-normal group. Blood samples from children and adults participants (1 to 70 years old) with uncomplicated P. falciparum malaria residing in Kambila, Mali were analysed. Study participants were randomly assigned to receive either artemether-lumefantrine (Coartem®) or artesunate plus mefloquine (Artequin™). A restriction-fragment length polymorphism analysis of PCR-amplified DNA samples was used to identify the (A-) allele of the gene mutation responsible for G6PD deficiency (G6PD*A-). 470 blood samples were thus analysed and of these, DNA was extracted from 315 samples using the QIAamp kit for PCR to identify the G6PD*A- gene. The DNA amplified from 315 samples using PCR showed that G6PD*A- deficiency was present in 56 participants (17.8%). The distribution of the specific deficiency was 1%, 7% and, 9.8% respectively for homozygous, hemizygous, and heterozygous genotypes. Before treatment, the median parasitaemia and other baseline characteristics (mean haemoglobin, sex and age groups) between G6PD deficiency (hemizygous, heterozygous, and homozygous) and G6PD-normal participants were comparable (p > 0.05). After treatment, parasite clearance did not change significantly whether the participants were G6PD deficient or G6PD normal on day 1 (OR = 1.3; CI = 0.70-2.47; p > 0.05) and on day 2 (OR = 0.859; CI = 0.097-7.61; p > 0.05). The presence of G6PD deficiency does not appear to significantly influence the clearance of P. falciparum in the treatment of uncomplicated malaria using ACT.

Return of chloroquine-sensitive Plasmodium falciparum parasites and emergence of chloroquine-resistant Plasmodium vivax in Ethiopia

PubMed Central

2014-01-01

Background Increased resistance by Plasmodium falciparum parasites led to the withdrawal of the antimalarial drugs chloroquine and sulphadoxine-pyrimethamine in Ethiopia. Since 2004 artemether-lumefantrine has served to treat uncomplicated P. falciparum malaria. However, increasing reports on delayed parasite clearance to artemisinin opens up a new challenge in anti-malarial therapy. With the complete withdrawal of CQ for the treatment of Plasmodium falciparum malaria, this study assessed the evolution of CQ resistance by investigating the prevalence of mutant alleles in the pfmdr1 and pfcrt genes in P. falciparum and pvmdr1 gene in Plasmodium vivax in Southern and Eastern Ethiopia. Methods Of the 1,416 febrile patients attending primary health facilities in Southern Ethiopia, 329 febrile patients positive for P. falciparum or P. vivax were recruited. Similarly of the 1,304 febrile patients from Eastern Ethiopia, 81 febrile patients positive for P. falciparum or P. vivax were included in the study. Of the 410 finger prick blood samples collected from malaria patients, we used direct sequencing to investigate the prevalence of mutations in pfcrt and pfmdr1. This included determining the gene copy number in pfmdr1 in 195 P. falciparum clinical isolates, and mutations in the pvmdr1 locus in 215 P. vivax clinical isolates. Results The pfcrt K76 CQ-sensitive allele was observed in 84.1% of the investigated P.falciparum clinical isolates. The pfcrt double mutations (K76T and C72S) were observed less than 3%. The pfcrt SVMNT haplotype was also found to be present in clinical isolates from Ethiopia. The pfcrt CVMNK-sensitive haplotypes were frequently observed (95.9%). The pfmdr1 mutation N86Y was observed only in 14.9% compared to 85.1% of the clinical isolates that carried sensitive alleles. Also, the sensitive pfmdr1 Y184 allele was more common, in 94.9% of clinical isolates. None of the investigated P. falciparum clinical isolates carried S1034C, N1042D and D1246Y pfmdr1 polymorphisms. All investigated P. falciparum clinical isolates from Southern and Eastern Ethiopia carried only a single copy of the mutant pfmdr1 gene. Conclusion The study reports for the first time the return of chloroquine sensitive P. falciparum in Ethiopia. These findings support the rationale for the use of CQ-based combination drugs as a possible future alternative. PMID:24964730

Therapeutic Efficacy of Chloroquine for the Treatment of Uncomplicated Plasmodium falciparum in Haiti after Many Decades of its Use

PubMed Central

Okech, Bernard A.; Existe, Alexandre; Romain, Jean R.; Memnon, Gladys; Victor, Yves Saint; de Rochars, Madsen Beau; Fukuda, Mark

2015-01-01

Chloroquine (CQ) has been used for malaria treatment in Haiti for several decades, but reports of CQ resistance are scarce. The efficacy of CQ in patients with uncomplicated Plasmodium falciparum undergoing treatment in Haiti was evaluated. Malaria patients were enrolled, treated with CQ, and monitored over a 42-day period. The treatment outcomes were evaluated on day 28 by microscopy. The P. falciparum slide-confirmed rate was 9.5% (121 of 1,277). Malaria infection was seasonal, with peak observations between October and January; 88% (107 of 121) of patients consented to participate. Sixty patients successfully completed the 42-day follow-up, whereas 47 patients withdrew consent or were lost to follow-up. The mean parasite density declined rapidly within the first few days after treatment. Seven patients did not clear their malaria infections and were clinically asymptomatic; therefore, they were considered late parasitological failures. About 90% (95% confidence interval = 84.20–97.90) of patients had no detectable parasitemia by day 28 and remained malaria-free to day 42. Testing for recrudescence, reinfection, and CQ serum levels was not done in the seven patients, and therefore, their CQ resistance status is unresolved. CQ resistance surveillance by patient follow-up, in vitro drug sensitivity studies, and molecular markers is urgently needed in Haiti. PMID:25601993

Cost-effectiveness of artemisinin-naphthoquine versus artemether-lumefantrine for the treatment of uncomplicated malaria in Papua New Guinean children.

PubMed

Moore, Brioni R; Davis, Wendy A; Clarke, Philip M; Robinson, Leanne J; Laman, Moses; Davis, Timothy M E

2017-10-30

A recent randomized trial showed that artemisinin-naphthoquine (AN) was non-inferior to artemether-lumefantrine (AL) for falciparum malaria and superior for vivax malaria in young Papua New Guinean children. The aim of this study was to compare the cost-effectiveness of these two regimens. An incremental cost-effectiveness analysis was performed using data from 231 children with Plasmodium falciparum and/or Plasmodium vivax infections in an open-label, randomized, parallel-group trial. Recruited children were randomized 1:1 to receive once daily AN for 3 days with water or twice daily AL for 3 days given with fat. World Health Organisation (WHO) definitions were used to determine clinical/parasitological outcomes. The cost of transport between the home and clinic, plus direct health-care costs, served as a basis for determining each regimen's incremental cost per incremental treatment success relative to AL by Day 42 and its cost per life year saved. In the usual care setting, AN was more effective for the treatment of uncomplicated malaria in children aged 0.5-5.9 years. AL and AN were equally efficacious for the treatment of falciparum malaria, however AN had increased anti-malarial treatment costs per patient of $10.46, compared with AL. AN was the most effective regimen for treatment of vivax malaria, but had increased treatment costs of $14.83 per treatment success compared with AL. Whilst AN has superior overall efficacy for the treatment of uncomplicated malaria in PNG children, AL was the less costly regimen. An indicative extrapolation estimated the cost per life year saved by using AN instead of AL to treat uncomplicated malaria to be $12,165 for girls and $12,469 for boys (discounted), which means AN may not be cost-effective and affordable for PNG at current cost. However, AN may become acceptable should it become WHO prequalified and/or should donated/subsidized drug supply become available.

A systematic review of the safety and efficacy of artemether-lumefantrine against uncomplicated Plasmodium falciparum malaria during pregnancy.

PubMed

Manyando, Christine; Kayentao, Kassoum; D'Alessandro, Umberto; Okafor, Henrietta U; Juma, Elizabeth; Hamed, Kamal

2012-05-01

Malaria during pregnancy, particularly Plasmodium falciparum malaria, has been linked to increased morbidity and mortality, which must be reduced by both preventive measures and effective case management. The World Health Organization (WHO) recommends artemisinin-based combination therapy (ACT) to treat uncomplicated falciparum malaria during the second and third trimesters of pregnancy, and quinine plus clindamycin during the first trimester. However, the national policies of many African countries currently recommend quinine throughout pregnancy. Therefore, the aim of this article is to provide a summary of the available data on the safety and efficacy of artemether-lumefantrine (AL) in pregnancy. An English-language search identified 16 publications from 1989 to October 2011 with reports of artemether or AL exposure in pregnancy, including randomized clinical trials, observational studies and systematic reviews. Overall, there were 1,103 reports of AL use in pregnant women: 890 second/third trimester exposures; 212 first trimester exposures; and one case where the trimester of exposure was not reported. In the second and third trimesters, AL was not associated with increased adverse pregnancy outcomes as compared with quinine or sulphadoxine-pyrimethamine, showed improved tolerability relative to quinine, and its efficacy was non-inferior to quinine. There is evidence to suggest that the pharmacokinetics of anti-malarial drugs may change in pregnancy, although the impact on efficacy and safety needs to be studied further, especially since the majority of studies report high cure rates and adequate tolerability. As there are fewer reports of AL safety in the first trimester, additional data are required to assess the potential to use AL in the first trimester. Though the available safety and efficacy data support the use of AL in the second and third trimesters, there is still a need for further information. These findings reinforce the WHO recommendation to treat uncomplicated falciparum malaria with quinine plus clindamycin in early pregnancy and ACT in later pregnancy.

Pyronaridine-artesunate and artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in Kenyan children: a randomized controlled non-inferiority trial.

PubMed

Roth, Johanna M; Sawa, Patrick; Makio, Nicodemus; Omweri, George; Osoti, Victor; Okach, Selpha; Choy, Felix; Schallig, Henk D F H; Mens, Pètra

2018-05-15

Pyronaridine-artesunate is a novel artemisinin-based combination therapy. The efficacy and safety of pyronaridine-artesunate were compared with artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in children. This phase III open-label randomized controlled non-inferiority trial was conducted in Western Kenya. Children aged 6 months to ≤ 12 years with a bodyweight > 5 kg and microscopically confirmed P. falciparum malaria were randomly assigned in a 1:1 ratio to orally receive pyronaridine-artesunate or artemether-lumefantrine, dosed according to bodyweight, for 3 days. Of 197 participants, 101 received pyronaridine-artesunate and 96 received artemether-lumefantrine. The day-28 adequate clinical and parasitological response in the per-protocol population, PCR-corrected for reinfections, was 98.9% (93/94, 95% CI 94.2-99.8) for pyronaridine-artesunate and 96.4% (81/84, 95% CI 90.0-98.8) for artemether-lumefantrine. Pyronaridine-artesunate was found to be non-inferior to artemether-lumefantrine: the treatment difference was 2.5% (95% CI - 2.8 to 9.0). Adverse events occurred in 41.6% (42/101) and 34.4% (33/96) of patients in the pyronaridine-artesunate group and the artemether-lumefantrine group, respectively. No participants were found to have alanine or aspartate aminotransferase levels > 3 times the upper limit of normal. Pyronaridine-artesunate was well tolerated, efficacious and non-inferior to artemether-lumefantrine for the treatment of uncomplicated P. falciparum malaria in Kenyan children. Results are in line with previous reports and inclusion of pyronaridine-artesunate in paediatric malaria treatment programmes should be considered. This study is registered at clinicaltrials.gov under NCT02411994. Registration date: 8 April 2015. https://clinicaltrials.gov/ct2/show/NCT02411994?term=pyronaridine-artesunate&cond=Malaria&cntry=KE&rank=1.

Phase 2a, Open-Label, 4-Escalating-Dose, Randomized Multicenter Study Evaluating the Safety and Activity of Ferroquine (SSR97193) Plus Artesunate, versus Amodiaquine Plus Artesunate, in African Adult Men with Uncomplicated Plasmodium falciparum Malaria.

PubMed

Supan, Christian; Mombo-Ngoma, Ghyslain; Kombila, Maryvonne; Ospina Salazar, Carmen L; Held, Jana; Lell, Bertrand; Cantalloube, Cathy; Djeriou, Elhadj; Ogutu, Bernhards; Waitumbi, John; Otsula, Nekoye; Apollo, Duncan; Polhemus, Mark E; Kremsner, Peter G; Walsh, Douglas S

2017-08-01

Artemisinin-based combination therapies are recommended as first-line agents for treating uncomplicated Plasmodium falciparum malaria. Ferroquine, a 4-aminoquinolone, is a novel long-acting combination partner for fast-acting drugs like artesunate (AS). We did a small phase 2a, multicenter, open-label, safety-focused dose-ranging randomized study of ferroquine at three African hospitals: two Gabonese and one Kenyan. We recruited adult men with symptomatic uncomplicated P. falciparum monoinfection. Four escalating doses of ferroquine (100, 200, 400, and 600 mg) were assessed in sequence, versus an amodiaquine comparator. After a 2:1 randomization (block size three, equating to N = 12 for each ferroquine dose and N = 6 for each of four amodiaquine comparator groups) patients received daily for three consecutive days, either ferroquine + AS (200 mg/day) or amodiaquine (612 mg/day) + AS (200 mg/day). Safety, electrocardiograms, parasite clearance times, efficacy, and pharmacokinetics were assessed to day 28. Seventy-two patients were randomized. Ferroquine + AS showed generally mild increases (Grade 1 toxicity) in alanine aminotransferase (ALT) levels with a dose trend starting at 400 mg. There were two Grade 2 ALT events: one patient receiving 200 mg (3.8 upper limit of normal [ULN], day 7) and one receiving 600 mg (3.3 ULN, day 14), both without increased bilirubin. One ferroquine 100 mg + AS patient after one dose was withdrawn after developing a QTcF interval prolongation > 60 milliseconds over baseline. Parasitemias in all patients cleared quickly, with no recurrence through day 28. Hepatic, as well as cardiac, profiles should be monitored closely in future trials. (ClinicalTrials.gov: NCT00563914).

Efficacy and Effectiveness of Mefloquine and Artesunate Combination Therapy for Uncomplicated Plasmodium falciparum Malaria in the Peruvian Amazon

PubMed Central

de Oliveira, Alexandre Macedo; Chavez, Jorge; de Leon, Gabriel Ponce; Durand, Salomon; Arrospide, Nancy; Roberts, Jacquelin; Cabezas, Cesar; Marquiño, Wilmer

2011-01-01

We evaluated the efficacy and effectiveness of mefloquine (MQ) plus artesunate (AS) to treat patients with uncomplicated malaria in the Peruvian Amazon Basin in April 2005–March 2006. Patients ≥ 1 year of age with fever (axillary temperature ≥ 37.5°C) or history of fever and Plasmodium falciparum monoinfection were included. Patients received antimalarial treatment with MQ (12.5 mg/kg/day for two days) and AS (4.0 mg/kg/day for three days) either by directly observed therapy or without directly observed therapy. After a 28-day follow-up, treatment efficacy and effectiveness were assessed on the basis of clinical and parasitologic outcomes. Ninety-six patients were enrolled in each study group; nine patients were lost to follow-up. All patients, except for one in the observed group, demonstrated adequate clinical and parasitologic response; none had detectable parasitemia on day 3. The efficacy of MQ + AS efficacy was 98.9% (95% confidence interval = 94.1–100.0%) and the effectiveness was 100.0% (95% confidence interval = 95.9–100.0%). Our study shows that MQ + AS is highly efficacious in the Peruvian Amazon. PMID:21896825

Low risk of recurrence following artesunate-Sulphadoxine-pyrimethamine plus primaquine for uncomplicated Plasmodium falciparum and Plasmodium vivax infections in the Republic of the Sudan.

PubMed

Hamid, Muzamil Mahdi Abdel; Thriemer, Kamala; Elobied, Maha E; Mahgoub, Nouh S; Boshara, Salah A; Elsafi, Hassan M H; Gumaa, Suhaib A; Hamid, Tassneem; Abdelbagi, Hanadi; Basheir, Hamid M; Marfurt, Jutta; Chen, Ingrid; Gosling, Roly; Price, Ric N; Ley, Benedikt

2018-03-16

First-line schizontocidal treatment for uncomplicated malaria in the Republic of the Sudan is artesunate (total dose 12 mg/kg) plus Sulphadoxine/pyrimethamine (25/1.25 mg/kg) (AS/SP). Patients with Plasmodium vivax are also treated with 14 days primaquine (total dose 3.5 mg/kg) (PQ). The aim of this study was to assess the efficacy of the national policy. Patients above 1 year, with microscopy-confirmed, Plasmodium falciparum and/or P. vivax malaria were treated with AS/SP. Patients with P. falciparum were randomized to no primaquine (Pf-noPQ) or a single 0.25 mg/kg dose of PQ (Pf-PQ1). Patients with P. vivax received 14 days unsupervised 3.5 mg/kg PQ (Pv-PQ14) on day 2 or at the end of follow up (Pv-noPQ). Primary endpoint was the risk of recurrent parasitaemia at day 42. G6PD activity was measured by spectrophotometry and the Accessbio Biosensor™. 231 patients with P. falciparum (74.8%), 77 (24.9%) with P. vivax and 1 (0.3%) patient with mixed infection were enrolled. The PCR corrected cumulative risk of recurrent parasitaemia on day 42 was 3.8% (95% CI 1.2-11.2%) in the Pf-noPQ arm compared to 0.9% (95% CI 0.1-6.0%) in the Pf-PQ1 arm; (HR = 0.25 [95% CI 0.03-2.38], p = 0.189). The corresponding risks of recurrence were 13.4% (95% CI 5.2-31.9%) in the Pv-noPQ arm and 5.3% (95% CI 1.3-19.4%) in the Pv-PQ14 arm (HR 0.36 [95% CI 0.1-2.0], p = 0.212). Two (0.9%) patients had G6PD enzyme activity below 10%, 19 (8.9%) patients below 60% of the adjusted male median. Correlation between spectrophotometry and Biosensor™ was low (r s  = 0.330, p < 0.001). AS/SP remains effective for the treatment of P. falciparum and P. vivax. The addition of PQ reduced the risk of recurrent P. falciparum and P. vivax by day 42, although this did not reach statistical significance. The version of the Biosensor™ assessed is not suitable for routine use. Trial registration https://clinicaltrials.gov/ct2/show/NCT02592408.

Lack of artemisinin resistance in Plasmodium falciparum in northwest Benin after 10 years of use of artemisinin-based combination therapy.

PubMed

Ogouyèmi-Hounto, Aurore; Damien, Georgia; Deme, Awa Bineta; Ndam, Nicaise T; Assohou, Constance; Tchonlin, Didier; Mama, Atika; Hounkpe, Virgile Olivier; Moutouama, Jules Doumitou; Remoué, Franck; Ndiaye, Daouda; Gazard, Dorothée Kinde

2016-01-01

In Benin, artemisinin-based combination therapy (ACT) has been recommended as the first-line treatment for uncomplicated Plasmodium falciparum malaria since 2004. The emergence in Southeast Asia of parasites that are resistant to artemisinins poses a serious threat to global control of this disease. The presence of artemisinin resistance genotypes in parasite populations in Benin is currently unknown. The present study investigated the prevalence of relevant K13-propeller gene polymorphisms in parasite isolates from the north-western region of Benin. Plasmodium falciparum isolates were collected from children with a confirmed diagnosis of malaria aged 6 months to 5 years in two towns, Cobly and Djougou, in the north-western part of Benin. The study was conducted during the rainy season from July to November 2014 in local health facilities. The K13-propeller gene was amplified in parasite isolates using nested PCR and subsequently sequenced. A total of 108 children were recruited into the study. The efficiency of amplification reactions was 72% (78/108). The propeller domain of the K13 gene was successfully sequenced in 78 P. falciparum isolates; all of them were wild type with no polymorphisms detectable. The absence of mutations in the K13 gene indicates that P. falciparum parasite populations in the study area are still fully susceptible to artemisinins. © A. Ogouyèmi-Hounto et al., published by EDP Sciences, 2016.

Relative Susceptibilities of ABO Blood Groups to Plasmodium falciparum Malaria in Ghana.

PubMed

Afoakwah, Richmond; Aubyn, Edmond; Prah, James; Nwaefuna, Ekene Kwabena; Boampong, Johnson N

2016-01-01

The clinical outcome of falciparum malaria in endemic areas is influenced by erythrocyte polymorphisms including the ABO blood groups. Studies have reported association of ABO blood group to resistance, susceptibility, and severity of P. falciparum malaria infection. Individuals with blood group "A" have been found to be highly susceptible to falciparum malaria whereas blood group "O" is said to confer protection against complicated cases. We analyzed samples from 293 young children less than six years old with malaria in the Korle-Bu Teaching Hospital in Accra, Ghana. It was observed that group O was present in about 16.1% of complicated cases weighed against 40.9% of uncomplicated controls. Individuals with complicated malaria were about twice likely to be of blood groups A and B compared to group O (A versus O, OR = 1.90, 95% CI = 1.59-2.26, P < 0.0001; B versus O, OR = 1.82. 95% CI = 1.57-2.23, P < 0.0001). Blood group O participants with complicated diseases had low parasitaemia compared to the other blood groups (P < 0.0001). This may give blood group O individuals a survival advantage over the other groups in complicated malaria as suggested. Participants with complicated falciparum malaria were generally anaemic and younger than those with uncomplicated disease.

Utility of nested polymerase chain reaction over the microscopy and immuno-chromatographic test in the detection of Plasmodium species and their clinical spectrum.

PubMed

Ranjan, P; Ghoshal, U

2016-09-01

Though demonstration of Plasmodium parasite in peripheral blood on microscopy remains gold standard, it may miss some patients resulting in delay in instituting life-saving therapy. Studies on polymerase chain reaction (PCR), a highly sensitive and specific technique that also discriminates among different species of malaria parasite, are scanty. Hence, we aimed to evaluate the role of PCR in diagnosis and species identification of Plasmodium. Of 2186 febrile patients with clinical suspicion of malaria screened between July 2013 to February 2015, 561 patients fulfilled inclusion criteria. Microscopy, rapid diagnostic test (RDT) and PCR were performed to identify the parasite. Plasmodium was detected in 64/561 (11.40 %), 92/561 (16.40 %) and 78/561 (13.90 %) cases using microscopy, RDT and PCR, respectively. Of 78 positive cases by PCR, 47 (60.25 %) were confirmed as Plasmodium falciparum (P. falciparum), 28 (35.89 %) were Plasmodium vivax (P. vivax) and 3 (3.84 %) had mixed infections. Sensitivity and specificity of microscopy and RDT were 82.10 %, 100 % and 98.70 %, 96.90 %, respectively (p = 0.139). Of total 93 patients, 67 (72.04 %) were classified as complicated and 26 (27.96 %) were as uncomplicated. Creatinine (p = <0.001), conjugated bilirubin (p = 0.003) and total bilirubin (p = <0.001) level was elevated in complicated malaria along with renal (65 %) and liver dysfunction (25 %). In the present study, P. falciparum was responsible for 40/67 (59.70 %) cases of complicated malaria; P. vivax was also found in 17/67 (25.37 %) complicated cases using PCR. The findings highlight the alarming number of complicated vivax malaria in addition to falciparum. Moreover, PCR proved to be highly sensitive and specific test for detecting Plasmodium species.

Comparison of allele frequencies of Plasmodium falciparum merozoite antigens in malaria infections sampled in different years in a Kenyan population.

PubMed

Ochola-Oyier, Lynette Isabella; Okombo, John; Wagatua, Njoroge; Ochieng, Jacob; Tetteh, Kevin K; Fegan, Greg; Bejon, Philip; Marsh, Kevin

2016-05-06

Plasmodium falciparum merozoite antigens elicit antibody responses in malaria-endemic populations, some of which are clinically protective, which is one of the reasons why merozoite antigens are the focus of malaria vaccine development efforts. Polymorphisms in several merozoite antigen-encoding genes are thought to arise as a result of selection by the human immune system. The allele frequency distribution of 15 merozoite antigens over a two-year period, 2007 and 2008, was examined in parasites obtained from children with uncomplicated malaria. In the same population, allele frequency changes pre- and post-anti-malarial treatment were also examined. Any gene which showed a significant shift in allele frequencies was also assessed longitudinally in asymptomatic and complicated malaria infections. Fluctuating allele frequencies were identified in codons 147 and 148 of reticulocyte-binding homologue (Rh) 5, with a shift from HD to YH haplotypes over the two-year period in uncomplicated malaria infections. However, in both the asymptomatic and complicated malaria infections YH was the dominant and stable haplotype over the two-year and ten-year periods, respectively. A logistic regression analysis of all three malaria infection populations between 2007 and 2009 revealed, that the chance of being infected with the HD haplotype decreased with time from 2007 to 2009 and increased in the uncomplicated and asymptomatic infections. Rh5 codons 147 and 148 showed heterogeneity at both an individual and population level and may be under some degree of immune selection.

No Evidence of Delayed Parasite Clearance after Oral Artesunate Treatment of Uncomplicated Falciparum Malaria in Mali

PubMed Central

Maiga, Amelia W.; Fofana, Bakary; Sagara, Issaka; Dembele, Demba; Dara, Antoine; Traore, Oumar Bila; Toure, Sekou; Sanogo, Kassim; Dama, Souleymane; Sidibe, Bakary; Kone, Aminatou; Thera, Mahamadou A.; Plowe, Christopher V.; Doumbo, Ogobara K.; Djimde, Abdoulaye A.

2012-01-01

Plasmodium falciparum resistance to artemisinins by delayed parasite clearance is present in Southeast Asia. Scant data on parasite clearance after artemisinins are available from Africa, where transmission is high, burden is greatest, and artemisinin use is being scaled up. Children 1–10 years of age with uncomplicated malaria were treated with 7 days of artesunate and followed for 28 days. Blood smears were done every 8 hours until negative by light microscopy. Results were compared with a similar study conducted in the same village in 2002–2004. The polymerase chain reaction-corrected cure rate was 100%, identical to 2002–2004. By 24 hours after treatment initiation, 37.0% of participants had cleared parasitemia, compared with 31.9% in 2002–2004 (P = 0.5). The median parasite clearance time was 32 hours. Only one participant still had parasites at 48 hours and no participant presented parasitemia at 72 hours. Artesunate was highly efficacious, with no evidence of delayed parasite clearance. We provide baseline surveillance data for the emergence or dissemination of P. falciparum resistance in sub-Saharan Africa. PMID:22764287

Plasmodium falciparum clearance with artemisinin-based combination therapy (ACT) in patients with glucose-6-phosphate dehydrogenase deficiency in Mali

PubMed Central

2010-01-01

Background Artemisinin-based combination therapy (ACT) is currently the most effective medicine for the treatment of uncomplicated malaria. Artemisinin has previously been shown to increase the clearance of Plasmodium falciparum in malaria patients with haemoglobin E trait, but it did not increase parasite inhibition in an in vitro study using haemoglobin AS erythrocytes. The current study describes the efficacy of artemisinin derivatives on P. falciparum clearance in patients with glucose-6-phosphate dehydrogenase deficiency (G6PD), a haemoglobin enzyme deficiency, not yet studied in the same context, but nonetheless is a common in malaria endemic areas, associated with host protection against uncomplicated and severe malaria. The impact of G6PD deficiency on parasite clearance with ACT treatment was compared between G6PD-deficient patients and G6PD-normal group. Methods Blood samples from children and adults participants (1 to 70 years old) with uncomplicated P. falciparum malaria residing in Kambila, Mali were analysed. Study participants were randomly assigned to receive either artemether-lumefantrine (Coartem®) or artesunate plus mefloquine (Artequin™). A restriction-fragment length polymorphism analysis of PCR-amplified DNA samples was used to identify the (A-) allele of the gene mutation responsible for G6PD deficiency (G6PD*A-). 470 blood samples were thus analysed and of these, DNA was extracted from 315 samples using the QIAamp kit for PCR to identify the G6PD*A- gene. Results The DNA amplified from 315 samples using PCR showed that G6PD*A- deficiency was present in 56 participants (17.8%). The distribution of the specific deficiency was 1%, 7% and, 9.8% respectively for homozygous, hemizygous, and heterozygous genotypes. Before treatment, the median parasitaemia and other baseline characteristics (mean haemoglobin, sex and age groups) between G6PD deficiency (hemizygous, heterozygous, and homozygous) and G6PD-normal participants were comparable (p > 0.05). After treatment, parasite clearance did not change significantly whether the participants were G6PD deficient or G6PD normal on day 1 (OR = 1.3; CI = 0.70-2.47; p > 0.05) and on day 2 (OR = 0.859; CI = 0.097-7.61; p > 0.05). Conclusions The presence of G6PD deficiency does not appear to significantly influence the clearance of P. falciparum in the treatment of uncomplicated malaria using ACT. PMID:21092137

Molecular epidemiology of malaria in Cameroon. XXX. sequence analysis of Plasmodium falciparum ATPase 6, dihydrofolate reductase, and dihydropteroate synthase resistance markers in clinical isolates from children treated with an artesunate-sulfadoxine-pyrimethamine combination.

PubMed

Menemedengue, Virginie; Sahnouni, Khalifa; Basco, Leonardo; Tahar, Rachida

2011-07-01

Plasmodium falciparum dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes are reliable molecular markers for antifolate resistance. The P. falciparum ATPase 6 (pfatp6) gene has been proposed to be a potential marker for artemisinin resistance. In our previous clinical study, we showed that artesunate-sulfadoxine-pyrimethamine is highly effective against uncomplicated malaria in Yaoundé, Cameroon. In the present study, dhfr, dhps, and pfatp6 mutations in P. falciparum isolates obtained from children treated with artesunate-sulfadoxine-pyrimethamine were determined. All 61 isolates had wild-type Pfatp6 263, 623, and 769 alleles, and 11 (18%) had a single E431K substitution. Three additional mutations, E643Q, E432K, and E641Q, were detected. The results did not indicate any warning signal of serious concern (i.e., no parasites were seen with quintuple dhfr-dhps, DHFR Ile164Leu, or pfatp6 mutations), as confirmed by the high clinical efficacy of artesunate-sulfadoxine-pyrimethamine. Further studies are required to identify a molecular marker that reliably predicts artemisinin resistance.

Molecular Epidemiology of Malaria in Cameroon. XXX. Sequence Analysis of Plasmodium falciparum ATPase 6, Dihydrofolate Reductase, and Dihydropteroate Synthase Resistance Markers in Clinical Isolates from Children Treated with an Artesunate-Sulfadoxine-Pyrimethamine Combination

PubMed Central

Menemedengue, Virginie; Sahnouni, Khalifa; Basco, Leonardo; Tahar, Rachida

2011-01-01

Plasmodium falciparum dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes are reliable molecular markers for antifolate resistance. The P. falciparum ATPase 6 (pfatp6) gene has been proposed to be a potential marker for artemisinin resistance. In our previous clinical study, we showed that artesunate-sulfadoxine-pyrimethamine is highly effective against uncomplicated malaria in Yaoundé, Cameroon. In the present study, dhfr, dhps, and pfatp6 mutations in P. falciparum isolates obtained from children treated with artesunate-sulfadoxine-pyrimethamine were determined. All 61 isolates had wild-type Pfatp6 263, 623, and 769 alleles, and 11 (18%) had a single E431K substitution. Three additional mutations, E643Q, E432K, and E641Q, were detected. The results did not indicate any warning signal of serious concern (i.e., no parasites were seen with quintuple dhfr-dhps, DHFR Ile164Leu, or pfatp6 mutations), as confirmed by the high clinical efficacy of artesunate-sulfadoxine-pyrimethamine. Further studies are required to identify a molecular marker that reliably predicts artemisinin resistance. PMID:21734119

Combined chloroquine, sulfadoxine/pyrimethamine and primaquine against Plasmodium falciparum in Central Java, Indonesia

PubMed Central

Lederman, Edith R; Maguire, Jason D; Sumawinata, Iwa W; Chand, Krisin; Elyazar, Iqbal; Estiana, Lusi; Sismadi, Priyanto; Bangs, Michael J; Baird, J Kevin

2006-01-01

Background Chloroquine (CQ) or sulfadoxine-pyrimethamine (SP) monotherapy for Plasmodium falciparum often leads to therapeutic failure in Indonesia. Combining CQ with other drugs, like SP, may provide an affordable, available and effective option where artemisinin-combined therapies (ACT) are not licensed or are unavailable. Methods This study compared CQ (n = 29 subjects) versus CQ + SP (with or without primaquine; n = 88) for clinical and parasitological cure of uncomplicated falciparum malaria in the Menoreh Hills region of southern Central Java, Indonesia. Gametocyte clearance rates were measured with (n = 56 subjects) and without (n = 61) a single 45 mg dose of primaquine (PQ). Results After 28 days, 58% of subjects receiving CQ had cleared parasitaemia and remained aparasitaemic, compared to 94% receiving CQ combined with SP (p < 0.001). Msp-2 genotyping permitted reinfection-adjusted cure rates for CQ and CQ combined with SP, 70% and 99%, respectively (p = 0.0006). Conclusion Primaquine exerted no apparent affect on cure of asexual stage parasitaemia, but clearly accelerated clearance of gametocytes. CQ combined with SP was safe and well-tolerated with superior efficacy over CQ for P. falciparum parasitaemia in this study. PMID:17105658

Ferrocene-chloroquine analogues as antimalarial agents: in vitro activity of ferrochloroquine against 103 Gabonese isolates of Plasmodium falciparum.

PubMed

Pradines, B; Fusai, T; Daries, W; Laloge, V; Rogier, C; Millet, P; Panconi, E; Kombila, M; Parzy, D

2001-08-01

The in vitro activities of ferrochloroquine, chloroquine, quinine, mefloquine, halofantrine, amodiaquine, primaquine, atovaquone and artesunate were evaluated against Plasmodium falciparum isolates from children with uncomplicated malaria from Libreville (Gabon), using an isotopic, micro, drug susceptibility test. The IC(50) values for ferrochloroquine were in the range 0.43-30.9 nM and the geometric mean IC(50) for the 103 isolates was 10.8 nM (95% CI 8.6-13.5 nM), while the geometric means for chloroquine, quinine, mefloquine, amodiaquine and primaquine were 370 nM, 341 nM, 8.3 nM, 18.1 nM and 7.6 microM, respectively. Ferrochloroquine was active against P. falciparum isolates, 95% of which showed in vitro resistance to chloroquine. Weak positive significant correlations were observed between the responses to ferrochloroquine and that to chloroquine, amodiaquine and quinine, but too low to suggest cross-resistance. There was no significant correlation between the response to ferrochloroquine and those to mefloquine, halofantrine, primaquine, atovaquone or artesunate. Ferrochloroquine may be an important alternative drug for the treatment of chloroquine-resistant malaria.

Procalcitonin as a biomarker for severe Plasmodium falciparum disease: a critical appraisal of a semi-quantitative point-of-care test in a cohort of travellers with imported malaria.

PubMed

Hesselink, Dennis A; Burgerhart, Jan-Steven; Bosmans-Timmerarends, Hanna; Petit, Pieter; van Genderen, Perry J J

2009-09-01

Imported malaria occurs as a relatively rare event in developed countries. As a consequence, most clinicians have little experience in making clinical assessments of disease severity and decisions regarding the need for parenteral therapy or high-level monitoring. In this study, the diagnostic accuracy of procalcitonin (PCT) for severe Plasmodium falciparum disease was assessed in a cohort of 100 consecutive travellers with various species of imported malaria. In all patients, PCT was measured on admission with a semi-quantitative 'point-of-care' test. Patients with severe P. falciparum malaria had significantly higher median PCT levels on admission as compared with patients with uncomplicated P. falciparum disease. In addition, PCT levels in patients with non-falciparum malaria were also higher compared with patients with non-severe falciparum malaria but lower compared with severe P. falciparum malaria. At a cut-off point of 10 ng/mL, PCT had a sensitivity of 0,67 and a specificity of 0,94 for severe falciparum disease. However, at lower cut-off points the specificity and positive predictive value were rather poor although the sensitivity and negative predictive value remained high. Potential drawbacks in the interpretation of elevated PCT levels on admission may be caused by infections with non-falciparum species and by concomitant bacterial infections. Semi-quantitative determination of PCT on admission is of limited use in the initial clinical assessment of disease severity in travellers with imported malaria, especially in settings with limited experience with the treatment of malaria.

Gametocyte Clearance Kinetics Determined by Quantitative Magnetic Fractionation in Melanesian Children with Uncomplicated Malaria Treated with Artemisinin Combination Therapy.

PubMed

Karl, Stephan; Laman, Moses; Moore, Brioni R; Benjamin, John; Koleala, Tamarah; Ibam, Clemencia; Kasian, Bernadine; Siba, Peter M; Waltmann, Andreea; Mueller, Ivo; Woodward, Robert C; St Pierre, Timothy G; Davis, Timothy M E

2015-08-01

Quantitative magnetic fractionation and a published mathematical model were used to characterize between-treatment differences in gametocyte density and prevalence in 70 Papua New Guinean children with uncomplicated Plasmodium falciparum and/or Plasmodium vivax malaria randomized to one of two artemisinin combination therapies (artemether-lumefantrine or artemisinin-naphthoquine) in an intervention trial. There was an initial rise in peripheral P. falciparum gametocyte density with both treatments, but it was more pronounced in the artemisinin-naphthoquine group. Model-derived estimates of the median pretreatment sequestered gametocyte population were 21/μl for artemether-lumefantrine and 61/μl for artemisinin-naphthoquine (P < 0.001). The median time for P. falciparum gametocyte density to fall to <2.5/μl (below which transmission becomes unlikely) was 16 days in the artemether-lumefantrine group and 20 days in artemisinin-naphthoquine group (P < 0.001). Gametocyte prevalence modeling suggested that artemisinin-naphthoquine-treated children became gametocytemic faster (median, 2.2 days) than artemether-lumefantrine-treated children (median, 5.3 days; P < 0.001) and had a longer median P. falciparum gametocyte carriage time per individual (20 versus 13 days; P < 0.001). Clearance of P. vivax gametocytes was rapid (within 3 days) in both groups; however, consistent with the reappearance of asexual forms in the main trial, nearly 40% of children in the artemether-lumefantrine group developed P. vivax gametocytemia between days 28 and 42 compared with 3% of children in the artemisinin-naphthoquine group. These data suggest that artemisinin is less active than artemether against sequestered gametocytes. Greater initial gametocyte release after artemisinin-naphthoquine increases the period of potential P. falciparum transmission by 4 days relative to artemether-lumefantrine, but the longer elimination half-life of naphthoquine than of lumefantrine suppresses P. vivax recurrence and consequent gametocytemia. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Two novel mutations of pfdhps K540T and I588F, affecting sulphadoxine-pyrimethamine-resistant response in uncomplicated falciparum malaria at Banjar district, South Kalimantan Province, Indonesia

PubMed Central

2014-01-01

Background Mutations in pfdhfr and pfdhps genes have been shown to associate with sulphadoxine-pyrimethamine (SP) resistance of Plasmodium falciparum parasites. However, pfdhfr, pfdhps genotypes and the correlations to SP treatment outcome in Indonesia has not yet been well analysed. Methods After obtaining informed consent, 61 uncomplicated falciparum malaria patients were recruited in Banjar district, South Kalimantan Province, Indonesia, from October 2009 to August 2010. They were treated by a single oral dose of SP and its effects on clinical and parasitological status were followed until day 28 after treatment. Occasionally, a thick smear blood film for microscopy observation and blood spot on a filter paper for pfdhfr and pfdhps genotype analysis were collected. Results Pfdhfr and pfdhps genotypes from 24 P. falciparum-infected patients consisting of adequate clinical parasitological response (ACPR) (n = 6; 25.0%) and early treatment failure (ETF) (n = 10; 41.7%) or late parasitological failure (LPF) (n = 8; 33.3%) were obtained by sequencing. Two novel mutations of pfdhps gene, K540T and I588F, were determined in ten and five isolates, respectively. These mutations were present in the pfdhfr/pfdhps combined haplotypes of ANRNI/SGTGA (n = 6), ANRNL/SGTGA (n = 4), and ANRNI/SGEAA(588F) (n = 5), (mutation codons are bold typed); these haplotypes were mostly belonging to parasitological failure (ETF or LPF). The parasites acquiring five mutations in pfdhfr/pfdhps haplotypes and four mutations with additional I588F did not respond adequately to SP treatment. Conclusion Many of Plasmodium falciparum infected patients in Banjar district, South Kalimantan, Indonesia did not respond adequately to SP treatment and these low ineffectiveness of SP in this area was associated with two novel mutations of pfdhps, K540T and I588F. PMID:25187019

Two novel mutations of pfdhps K540T and I588F, affecting sulphadoxine-pyrimethamine-resistant response in uncomplicated falciparum malaria at Banjar district, South Kalimantan Province, Indonesia.

PubMed

Basuki, Sukmawati; Fitriah; Riyanto, Sugeng; Budiono; Dachlan, Yoes P; Uemura, Haruki

2014-04-04

Mutations in pfdhfr and pfdhps genes have been shown to associate with sulphadoxine-pyrimethamine (SP) resistance of Plasmodium falciparum parasites. However, pfdhfr, pfdhps genotypes and the correlations to SP treatment outcome in Indonesia has not yet been well analysed. After obtaining informed consent, 61 uncomplicated falciparum malaria patients were recruited in Banjar district, South Kalimantan Province, Indonesia, from October 2009 to August 2010. They were treated by a single oral dose of SP and its effects on clinical and parasitological status were followed until day 28 after treatment. Occasionally, a thick smear blood film for microscopy observation and blood spot on a filter paper for pfdhfr and pfdhps genotype analysis were collected. Pfdhfr and pfdhps genotypes from 24 P. falciparum-infected patients consisting of adequate clinical parasitological response (ACPR) (n = 6; 25.0%) and early treatment failure (ETF) (n = 10; 41.7%) or late parasitological failure (LPF) (n = 8; 33.3%) were obtained by sequencing. Two novel mutations of pfdhps gene, K540T and I588F, were determined in ten and five isolates, respectively. These mutations were present in the pfdhfr/pfdhps combined haplotypes of ANRNI/SGTGA (n = 6), ANRNL/SGTGA (n = 4), and ANRNI/SGEAA(588F) (n = 5), (mutation codons are bold typed); these haplotypes were mostly belonging to parasitological failure (ETF or LPF). The parasites acquiring five mutations in pfdhfr/pfdhps haplotypes and four mutations with additional I588F did not respond adequately to SP treatment. Many of Plasmodium falciparum infected patients in Banjar district, South Kalimantan, Indonesia did not respond adequately to SP treatment and these low ineffectiveness of SP in this area was associated with two novel mutations of pfdhps, K540T and I588F.

Tumor necrosis factor -α, interleukin-10, intercellular and vascular adhesion molecules are possible biomarkers of disease severity in complicated Plasmodium vivax isolates from Pakistan.

PubMed

Raza, Afsheen; Ghanchi, Najia K; Sarwar Zubairi, Ali bin; Raheem, Ahmed; Nizami, Sobia; Beg, Mohammad Asim

2013-01-01

Cytokine-mediated endothelial activation pathway is a known mechanism of pathogenesis employed by Plasmodium falciparum to induce severe disease symptoms in human host. Though considered benign, complicated cases of Plasmodium vivax are being reported worldwide and from Pakistan. It has been hypothesized that P.vivax utilizes similar mechanism of pathogenesis, as that of P.falciparum for manifestations of severe malaria. Therefore, the main objective of this study was to characterize the role of cytokines and endothelial activation markers in complicated Plasmodium vivax isolates from Pakistan. A case control study using plasma samples from well-characterized groups suffering from P.vivax infection including uncomplicated cases (n=100), complicated cases (n=82) and healthy controls (n=100) were investigated. Base line levels of Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), Interleukin-10 (IL-10), Intercellular adhesion molecule-1 (ICAM-1), Vascular adhesion molecule-1(VCAM-1) and E-selectin were measured by ELISA. Correlation of cytokines and endothelial activation markers was done using Spearman's correlation analysis. Furthermore, significance of these biomarkers as indicators of disease severity was also analyzed. The results showed that TNF-α, IL-10, ICAM-1and VCAM-1 were 3-fold, 3.7 fold and 2 fold increased between uncomplicated and complicated cases. Comparison of healthy controls with uncomplicated cases showed no significant difference in TNF-α concentrations while IL-6, IL-10, ICAM-1, VCAM-1 and E-selectin were found to be elevated respectively. In addition, significant positive correlation was observed between TNF-α and IL-10/ ICAM-1, IL-6 and IL-10, ICAM-1 and VCAM-1.A Receiver operating curve (ROC) was generated which showed that TNF-α, IL-10, ICAM-1 and VCAM-1 were the best individual predictors of complicated P.vivax malaria. The results suggest that though endothelial adhesion molecules are inducible by pro-inflammatory cytokine TNF-α, however, cytokine-mediated endothelial activation pathway is not clearly demonstrated as a mechanism of pathogenesis in complicated P.vivax malaria cases from Pakistan.

Pharmacokinetic and pharmacodynamic characteristics of a new pediatric formulation of artemether-lumefantrine in African children with uncomplicated Plasmodium falciparum malaria.

PubMed

Djimdé, Abdoulaye A; Tekete, Mamadou; Abdulla, Salim; Lyimo, John; Bassat, Quique; Mandomando, Inacio; Lefèvre, Gilbert; Borrmann, Steffen

2011-09-01

The pharmacokinetic and pharmacodynamic properties of a new pediatric formulation of artemether-lumefantrine, dispersible tablet, were determined within the context of a multicenter, randomized, parallel-group study. In an exploratory approach, we compared a new pediatric formulation with the tablet formulation administered crushed in the treatment of African children with uncomplicated Plasmodium falciparum malaria. Patients were randomized to 3 different dosing groups (weights of 5 to <15 kg, 15 and <25 kg, and 25 to <35 kg). Treatment was administered twice daily over 3 days. Plasma concentrations of artemether and its active metabolite, dihydroartemisinin (DHA), were determined at 1 and 2 h after the first dose of dispersible (n = 91) and crushed (n = 93) tablets. A full pharmacokinetic profile of lumefantrine was reconstituted on the basis of 310 (dispersible tablet) and 315 (crushed tablet) plasma samples, collected at 6 different time points (1 sample per patient). Dispersible and crushed tablets showed similar artemether and DHA maximum concentrations in plasma (C(max)) for the different body weight groups, with overall means of 175 ± 168 and 190 ± 168 ng/ml, respectively, for artemether and 64.7 ± 58.1 and 63.7 ± 65.0 ng/ml, respectively, for DHA. For lumefantrine, the population C(max) were 6.3 μg/ml (dispersible tablet) and 7.7 μg/ml (crushed tablet), whereas the areas under the concentration-time curves from time zero to the time of the last quantifiable plasma concentration measured were 574 and 636 μg · h/ml, respectively. For both formulations, descriptive quintile analyses showed no apparent association between artemether/DHA C(max) and parasite clearance time or between the lumefantrine C(max) and the occurrence of adverse events or corrected QT interval changes. The results suggest that the dispersible tablet provides adequate systemic exposure to artemether, DHA, and lumefantrine in African children with uncomplicated P. falciparum malaria.

Uncomplicated Plasmodium vivax malaria in pregnancy associated with mortality from acute respiratory distress syndrome.

PubMed

McGready, Rose; Wongsaen, Klanarong; Chu, Cindy S; Tun, Nay Win; Chotivanich, Kesinee; White, Nicholas J; Nosten, François

2014-05-27

The association between severe malaria and Plasmodium vivax species is contentious. On the Thai-Myanmar border, all pregnant women are followed systematically with active weekly malaria screening. Over a 27-year period of providing antenatal care, 48,983 have been prospectively followed until pregnancy outcome (miscarriage or delivery) and 4,298 women have had P. vivax detected at least once. Reported here is the first known P. vivax-associated death amongst these women. The initial patient presentation was of uncomplicated P. vivax (0.5% parasitaemia) in a term, multigravida woman who responded rapidly to oral artesunate and mefloquine treatment, clearing her blood stage parasites within 48 hours. The patient appeared well, was ambulatory and due to be discharged but became unwell with acute respiratory distress syndrome (ARDS) requiring ventilation three days (67 hours) into treatment. Despite induction and delivery of a stillborn foetus, ventilatory requirements increased and the patient died on day 7. The patient had a low body mass index. Sensitive detection with nested PCR confirmed only the presence of P. vivax species and concomitant infections such as tuberculosis and human immunodeficiency virus (HIV) were also ruled out. The contemporaneous treatment of acute uncomplicated P. vivax and the onset of ARDS on day 3 in this patient implies a possible but unconfirmed association with death in this patient. Assuming this death was caused by P. vivax, the risk of ARDS-related maternal mortality in this setting did not differ significantly between Plasmodium falciparum and P. vivax (0.24 per 1,000 (1/4,158) versus 0.23 per 1,000 (1/4,298), contrary to the increased risk of maternal mortality from P. falciparum compared to P. vivax, 2.89 per 1,000 (12/4,158) versus 0.23 per 1,000 (1/4,298), P = 0.003.

Baseline in vivo, ex vivo and molecular responses of Plasmodium falciparum to artemether and lumefantrine in three endemic zones for malaria in Colombia.

PubMed

Aponte, Samanda; Guerra, Ángela Patricia; Álvarez-Larrotta, Catalina; Bernal, Sindy Durley; Restrepo, César; González, Camila; Yasnot, María Fernanda; Knudson-Ospina, Angélica

2017-02-01

Colombia began using artemisinin-based combination therapies for the treatment of uncomplicated Plasmodium falciparum malaria in 2006. It is necessary to implement resistance surveillance to antimalarial drugs in order to promptly detect changes in parasite susceptibility. The aim of this study was to establish a susceptibility baseline of P. falciparum to artemether-lumefantrine using three monitoring tools. Patients with uncomplicated malaria treated with artemether-lumefantrine underwent clinical and parasitological follow-up over 28 days. Ex vivo test was performed using the microtest technique for chloroquine, arthemeter, dihydroartemisinin and lumefantrine. Pfmdr1 copy number and polymorphisms in Pfk13, Pfatp6, Pfcrt and Pfmdr1 genes were analyzed. From a total of 150 screened patients, 49 completed follow-up for 28 days. All treated patients had adequate clinical and parasitological responses. Parasitic clearance showed a drastic reduction of parasite biomass at 24 hours and complete elimination at 48 hours. One hundred eleven isolates were processed, all exhibited high susceptibility to artemisinins and a slight decrease in susceptibility to lumefantrine. No genetic polymorphisms associated with resistance to artemisinin were found. This study generated a susceptibility baseline in response to therapy with Coartem (artemether-lumefantrine) with numerical reference values, which will allow data comparison with future studies to systematically monitor changes in the parasite and to provide an early alert to the health authorities. © The Author 2017. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Evidence for the contribution of the hemozoin synthesis pathway of the murine Plasmodium yoelii to the resistance to artemisinin-related drugs.

PubMed

Witkowski, Benoit; Lelièvre, Joel; Nicolau-Travers, Marie-Laure; Iriart, Xavier; Njomnang Soh, Patrice; Bousejra-Elgarah, Fatima; Meunier, Bernard; Berry, Antoine; Benoit-Vical, Françoise

2012-01-01

Plasmodium falciparum malaria is a major global health problem, causing approximately 780,000 deaths each year. In response to the spreading of P. falciparum drug resistance, WHO recommended in 2001 to use artemisinin derivatives in combination with a partner drug (called ACT) as first-line treatment for uncomplicated falciparum malaria, and most malaria-endemic countries have since changed their treatment policies accordingly. Currently, ACT are often the last treatments that can effectively and rapidly cure P. falciparum infections permitting to significantly decrease the mortality and the morbidity due to malaria. However, alarming signs of emerging resistance to artemisinin derivatives along the Thai-Cambodian border are of major concern. Through long-term in vivo pressures, we have been able to select a murine malaria model resistant to artemisinins. We demonstrated that the resistance of Plasmodium to artemisinin-based compounds depends on alterations of heme metabolism and on a loss of hemozoin formation linked to the down-expression of the recently identified Heme Detoxification Protein (HDP). These artemisinins resistant strains could be able to detoxify the free heme by an alternative catabolism pathway involving glutathione (GSH)-mediation. Finally, we confirmed that artemisinins act also like quinolines against Plasmodium via hemozoin production inhibition. The work proposed here described the mechanism of action of this class of molecules and the resistance to artemisinins of this model. These results should help both to reinforce the artemisinins activity and avoid emergence and spread of endoperoxides resistance by focusing in adequate drug partners design. Such considerations appear crucial in the current context of early artemisinin resistance in Asia.

Evidence for the Contribution of the Hemozoin Synthesis Pathway of the Murine Plasmodium yoelii to the Resistance to Artemisinin-Related Drugs

PubMed Central

Nicolau-Travers, Marie-Laure; Iriart, Xavier; Njomnang Soh, Patrice; Bousejra-ElGarah, Fatima; Meunier, Bernard; Berry, Antoine; Benoit-Vical, Françoise

2012-01-01

Plasmodium falciparum malaria is a major global health problem, causing approximately 780,000 deaths each year. In response to the spreading of P. falciparum drug resistance, WHO recommended in 2001 to use artemisinin derivatives in combination with a partner drug (called ACT) as first-line treatment for uncomplicated falciparum malaria, and most malaria-endemic countries have since changed their treatment policies accordingly. Currently, ACT are often the last treatments that can effectively and rapidly cure P. falciparum infections permitting to significantly decrease the mortality and the morbidity due to malaria. However, alarming signs of emerging resistance to artemisinin derivatives along the Thai-Cambodian border are of major concern. Through long-term in vivo pressures, we have been able to select a murine malaria model resistant to artemisinins. We demonstrated that the resistance of Plasmodium to artemisinin-based compounds depends on alterations of heme metabolism and on a loss of hemozoin formation linked to the down-expression of the recently identified Heme Detoxification Protein (HDP). These artemisinins resistant strains could be able to detoxify the free heme by an alternative catabolism pathway involving glutathione (GSH)-mediation. Finally, we confirmed that artemisinins act also like quinolines against Plasmodium via hemozoin production inhibition. The work proposed here described the mechanism of action of this class of molecules and the resistance to artemisinins of this model. These results should help both to reinforce the artemisinins activity and avoid emergence and spread of endoperoxides resistance by focusing in adequate drug partners design. Such considerations appear crucial in the current context of early artemisinin resistance in Asia. PMID:22403683

Therapeutic efficacy of sulfadoxine-pyrimethamine, amodiaquine and the sulfadoxine-pyrimethamine-amodiaquine combination against uncomplicated Plasmodium falciparum malaria in young children in Cameroon.

PubMed Central

Basco, Leonardo K.; Same-Ekobo, Albert; Ngane, Vincent Foumane; Ndounga, Mathieu; Metoh, Theresia; Ringwald, Pascal; Soula, Georges

2002-01-01

OBJECTIVE: To evaluate the therapeutic efficacy of sulfadoxine-pyrimethamine, amodiaquine, and the sulfadoxine-pyrimethamine-amodiaquine combination for the treatment of uncomplicated Plasmodium falciparum malaria in young children in Cameroon. METHODS: In a randomized study we evaluated the effectiveness and tolerance of (i) sulfadoxine-pyrimethamine (SP) (25 mg/kg body weight of sulfadoxine and 1.25 mg/kg of pyrimethamine in a single oral dose), (ii) amodiaquine (AQ) (30 mg/kg body weight in three divided daily doses), and (iii) the sulfadoxine-pyrimethamine-amodiaquine combination (SP+AQ) (same doses as in the other two treatment groups, given simultaneously on day 0) in young children in southern Cameroon. The parasitological and clinical responses were studied until day 28 in accordance with the modified 1996 WHO protocol for the evaluation of the therapeutic efficacy of antimalarial drugs. FINDINGS: Of 191 enrolled patients, 6 and 8 were excluded or lost to follow-up before day 14 and between day 14 and day 28, respectively. For the AQ-treated patients, parasitological and clinical evaluation on day 14 showed late treatment failure in 2 of 61 (3.3%) and adequate clinical response with parasitological failure in one (1.6%). There was an adequate clinical response in all patients treated with SP or SP+AQ. Therapeutic failure rates on day 28 were 13.6%, 10.2% and 0% in the SP, AQ, and SP+AQ groups, respectively. Anaemia improved in all three regimens. AQ produced faster fever clearance but was associated with more transient minor side-effects than SP. SP+AQ reduced the risk of recrudescence between day 14 and day 28 but increased the incidence of minor side-effects. CONCLUSION: SP+AQ can be recommended as a temporary means of slowing the spread of multidrug resistance in Plasmodium falciparum in Africa while the introduction of other combinations, including artemisinin derivatives, is awaited. PMID:12163917

Treating uncomplicated malaria in children: comparing artemisinin-based combination therapies.

PubMed

Yeka, Adoke; Harris, Jamal C

2010-12-01

In response to increased resistance to conventional drugs, the WHO is promoting artemisinin-based combination therapy (ACT) for treating uncomplicated malaria. The objective of this report is to review the available evidence on the efficacy and effectiveness, acceptability, and deployment of ACT in resource-limited settings with a focus on sub-Saharan Africa. ACTs are very effective in the treatment of uncomplicated Plasmodium falciparum malaria in children. ACTs are relatively safe and tolerable with no reported resistance in sub-Saharan Africa despite indications of delayed clearance of infections in south-east Asia. The major challenges to the widespread use of ACT include its high cost, availability, and inefficient delivery due to, among other things, weak healthcare systems. ACTs are an essential tool in the fight to control and eliminate malaria. They are currently the most effective drugs against P. falciparum malaria. They should be deployed through programs that address availability, cost, adherence, and quality assurance. Initiatives including home-based management of malaria, improving public sector procurement and supply chains, and reducing private sector pricing should make ACTs more accessible for sub-Saharan African children who bear the brunt of the burden of malarial disease.

C-terminal polymorphism of Plasmodium falciparium merozoite surface protein-1 (MSP-1) from Tak Province, Thailand.

PubMed

Viputtigul, Kwanjai; Tungpukdee, Noppadon; Ruangareerate, Toon; Luplertlop, Natthanej; Wilairatana, Polrat; Gaywee, Jariyanart; Krudsood, Srivicha

2013-01-01

This study was undertaken to ascertain the extent of polymorphism in the C-terminal region of Plasmodium falciparum merozoite surface protein (MSP-1) from 119 malaria patients in Tak Province on the western border of Thailand, who were admitted to the Bangkok Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. P. falciparum infection was confirmed by microscopic examination of peripheral blood smears. Clinical manifestations were categorized into 2 groups: uncomplicated (94 cases) and complicated/severe (25 cases). A 1,040 basepair fragment of P. falciparum MSP-1 gene was compared with MSP-1 of reference strains retrieved from GenBank. The consensus sequences of MSP-1 block 16 showed it belonged to MAD20 genotype, which is the major allele of falciparum malaria from the western border of Thailand. MSP-1 block 16 amino acid fragment could be separated into 2 groups: similar and dissimilar to reference sequence. Four variations in MSP-1 block 16 were -1494K, D1510G, D1556N, and K1696I. MSP-1 block 16 diversity is not significantly associated with clinical manifestation although MAD 20 genotype is the predominant genotype in this area. The genetic data of MSP1 gene of faciparum malaria isolated from western Thai border contribute to the existing genetic database of Thai P. falciparum strain.

Influence of the pfmdr1 Gene on In Vitro Sensitivities of Piperaquine in Thai Isolates of Plasmodium falciparum

PubMed Central

Mungthin, Mathirut; Watanatanasup, Ekularn; Sitthichot, Naruemon; Suwandittakul, Nantana; Khositnithikul, Rommanee; Ward, Stephen A.

2017-01-01

Piperaquine combined with dihydroartemisinin is one of the artemisinin derivative combination therapies, which can replace artesunate–mefloquine in treating uncomplicated falciparum malaria in Thailand. The aim of this study was to determine the in vitro sensitivity of Thai Plasmodium falciparum isolates against piperaquine and the influence of the pfmdr1 gene on in vitro response. One hundred and thirty-seven standard laboratory and adapted Thai isolates of P. falciparum were assessed for in vitro piperaquine sensitivity. Polymorphisms of the pfmdr1 gene were determined by polymerase chain reaction methods. The mean and standard deviation of the piperaquine IC50 in Thai isolates of P. falciparum were 16.7 ± 6.3 nM. The parasites exhibiting chloroquine IC50 of ≥ 100 nM were significantly less sensitive to piperaquine compared with the parasite with chloroquine IC50 of < 100 nM. No significant association between the pfmdr1 copy number and piperaquine IC50 values was found. In contrast, the parasites containing the pfmdr1 86Y allele exhibited significantly reduced piperaquine sensitivity. Before nationwide implementation of dihydroartemisinin–piperaquine as the first-line treatment in Thailand, in vitro and in vivo evaluations of this combination should be performed especially in areas where parasites containing the pfmdr1 86Y allele are predominant such as the Thai–Malaysian border. PMID:28044042

Cytoadhesion to gC1qR through Plasmodium falciparum Erythrocyte Membrane Protein 1 in Severe Malaria

PubMed Central

Magallón-Tejada, Ariel; Machevo, Sónia; Cisteró, Pau; Lavstsen, Thomas; Aide, Pedro; Jiménez, Alfons; Turner, Louise; Gupta, Himanshu; De Las Salas, Briegel; Mandomando, Inacio; Wang, Christian W.; Petersen, Jens E. V.; Muñoz, Jose; Gascón, Joaquim; Macete, Eusebio; Alonso, Pedro L.; Chitnis, Chetan E.

2016-01-01

Cytoadhesion of Plasmodium falciparum infected erythrocytes to gC1qR has been associated with severe malaria, but the parasite ligand involved is currently unknown. To assess if binding to gC1qR is mediated through the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family, we analyzed by static binding assays and qPCR the cytoadhesion and var gene transcriptional profile of 86 P. falciparum isolates from Mozambican children with severe and uncomplicated malaria, as well as of a P. falciparum 3D7 line selected for binding to gC1qR (Pf3D7gC1qR). Transcript levels of DC8 correlated positively with cytoadhesion to gC1qR (rho = 0.287, P = 0.007), were higher in isolates from children with severe anemia than with uncomplicated malaria, as well as in isolates from Europeans presenting a first episode of malaria (n = 21) than Mozambican adults (n = 25), and were associated with an increased IgG recognition of infected erythrocytes by flow cytometry. Pf3D7gC1qR overexpressed the DC8 type PFD0020c (5.3-fold transcript levels relative to Seryl-tRNA-synthetase gene) compared to the unselected line (0.001-fold). DBLβ12 from PFD0020c bound to gC1qR in ELISA-based binding assays and polyclonal antibodies against this domain were able to inhibit binding to gC1qR of Pf3D7gC1qR and four Mozambican P. falciparum isolates by 50%. Our results show that DC8-type PfEMP1s mediate binding to gC1qR through conserved surface epitopes in DBLβ12 domain which can be inhibited by strain-transcending functional antibodies. This study supports a key role for gC1qR in malaria-associated endovascular pathogenesis and suggests the feasibility of designing interventions against severe malaria targeting this specific interaction. PMID:27835682

Neopterin and procalcitonin are suitable biomarkers for exclusion of severe Plasmodium falciparum disease at the initial clinical assessment of travellers with imported malaria.

PubMed

te Witt, René; van Wolfswinkel, Marlies E; Petit, Pieter L; van Hellemond, Jaap J; Koelewijn, Rob; van Belkum, Alex; van Genderen, Perry J J

2010-09-14

Most clinicians in developed, non-malaria endemic countries have limited or no experience in making clinical assessments of malaria disease severity and subsequent decisions regarding the need for parenteral therapy or high-level monitoring in febrile patients with imported malaria. In the present study, the diagnostic accuracy of plasma soluble Triggering Receptor Expressed on Myeloid cells 1 (TREM-1), neopterin and procalcitonin levels as biomarkers for severe Plasmodium falciparum disease was evaluated in 104 travellers with imported malaria (26 patients with non-P. falciparum malaria, 64 patients with uncomplicated P. falciparum malaria and 14 patients with severe P. falciparum malaria). TREM-1, neopterin and procalcitonin were determined in serum using commercially available ELISA or EIA tests. The diagnostic performance of these biomarkers for severe disease was compared with plasma lactate, a well-validated parameter for disease severity in patients with malaria, as reference. Severe malaria was defined according to the modified WHO criteria. No significant differences in TREM-1 levels were detected between the different patient groups. Patients with severe P. falciparum malaria had significantly higher neopterin and procalcitonin levels on admission when compared to patients with uncomplicated P. falciparum malaria or non-P. falciparum malaria. Receiver Operating Characteristic (ROC) curve analysis showed that neopterin had the highest Area-Under-the-ROC curve (AUROC 0.85) compared with plasma lactate (AUROC 0.80) and procalcitonin (AUROC 0.78). At a cut-off point of 10.0 ng/ml, neopterin had a positive and negative predictive value of 0.38 and 0.98 whereas procalcitonin, at a cut-off point of 0.9 ng/ml, had a positive and negative predictive value of 0.30 and 1.00. Although the diagnostic value of neopterin and procalcitonin is limited, the high negative predictive value of both neopterin and procalcitonin may be helpful for a rapid exclusion of severe malaria disease on admission. This may be a valuable tool for physicians only occasionally dealing with ill-returned travellers from malaria-endemic regions and who need to decide on subsequent oral anti-malarial treatment or timely referral to a specialized centre for high-level monitoring and intensified parenteral treatment.

Phenotypic and genotypic characterization of Thai isolates of Plasmodium falciparum after an artemisinin resistance containment project.

PubMed

Thita, Thunyapit; Jadsri, Pimrat; Thamkhantho, Jarupatr; Ruang-Areerate, Toon; Suwandittakul, Nantana; Sitthichot, Naruemon; Mahotorn, Kittiya; Tan-Ariya, Peerapan; Mungthin, Mathirut

2018-05-15

In Thailand, artemisinin-based combination therapy (ACT) has been used to treat uncomplicated falciparum malaria since 1995. Unfortunately, artemisinin resistance has been reported from Thailand and other Southeast Asian countries since 2003. Malarone ® , a combination of atovaquone-proguanil (ATQ-PG), has been used to cease artemisinin pressure in some areas along Thai-Cambodia border, as part of an artemisinin resistance containment project since 2009. This study aimed to determine genotypes and phenotypes of Plasmodium falciparum isolates collected from the Thai-Cambodia border after the artemisinin resistance containment project compared with those collected before. One hundred and nine of P. falciparum isolates collected from Thai-Cambodia border from Chanthaburi and Trat provinces during 1988-2016 were used in this study. Of these, 58 isolates were collected after the containment. These parasite isolates were characterized for in vitro antimalarial sensitivities including chloroquine (CQ), quinine (QN), mefloquine (MQ), piperaquine (PPQ), artesunate (AS), dihydroartemisinin (DHA), ATQ and PG and genetic markers for drug resistance including the Kelch13 (k13), Plasmodium falciparum chloroquine resistance transporter (pfcrt), P. falciparum multidrug resistance 1 (pfmdr1) and cytochrome b (cytb) genes. Mean CQ, QN, MQ, PPQ and AS IC 50 s of the parasite isolates collected from 2009 to 2016 exhibited significantly higher than those of parasites collected before 2009. Approximately 57% exhibited in vitro MQ resistance. Approximately 94% of the isolates collected from 2009 to 2016 contained the pfmdr1 184F allele. Mutations of the k13 gene were detected in approximately 90% of the parasites collected from 2009 to 2016 which were significantly higher than the parasite isolates collected before. No ATQ-resistant genotype and phenotype of P. falciparum were found among the isolates collected after the containment project. Although the containment project had been implemented in this area, the expansion of artemisinin-resistant parasites did not decline. In addition, reduced sensitivity of the partner drugs of ACT including MQ and PPQ were identified.

Safety of a single low-dose of primaquine in addition to standard artemether-lumefantrine regimen for treatment of acute uncomplicated Plasmodium falciparum malaria in Tanzania.

PubMed

Mwaiswelo, Richard; Ngasala, Billy E; Jovel, Irina; Gosling, Roland; Premji, Zul; Poirot, Eugenie; Mmbando, Bruno P; Björkman, Anders; Mårtensson, Andreas

2016-06-10

This study assessed the safety of the new World Health Organization (WHO) recommendation of adding a single low-dose of primaquine (PQ) to standard artemisinin-based combination therapy (ACT), regardless of individual glucose-6-phosphate dehydrogenase (G6PD) status, for treatment of acute uncomplicated Plasmodium falciparum malaria in Tanzania. Men and non-pregnant, non-lactating women aged ≥1 year with uncomplicated P. falciparum malaria were enrolled and randomized to either standard artemether-lumefantrine (AL) regimen alone or with a 0.25 mg/kg single-dose of PQ. PQ was administered concomitantly with the first AL dose. All drug doses were supervised. Safety was evaluated between days 0 and 28. G6PD status was assessed using rapid test (CareStart™) and molecular genotyping. The primary endpoint was mean percentage relative reduction in haemoglobin (Hb) concentration (g/dL) between days 0 and 7 by genotypic G6PD status and treatment arm. Overall, 220 patients, 110 per treatment arm, were enrolled, of whom 33/217 (15.2 %) were phenotypically G6PD deficient, whereas 15/110 (13.6 %) were genotypically hemizygous males, 5/110 (4.5 %) homozygous females and 22/110 (20 %) heterozygous females. Compared to genotypically G6PD wild-type/normal [6.8, 95 % confidence interval (CI) 4.67-8.96], only heterozygous patients in AL arm had significant reduction in day-7 mean relative Hb concentration (14.3, 95 % CI 7.02-21.55, p=0.045), however, none fulfilled the pre-defined haemolytic threshold value of ≥25 % Hb reduction. After adjustment for baseline parasitaemia, Hb, age and sex the mean relative Hb reduction was not statistically significant in both heterozygous and hemizygous/homozygous patients in both arms. A majority of the adverse events (AEs) were mild and unrelated to the study drugs. However, six (4.4 %) episodes, three per treatment arm, of acute haemolytic anaemia occurred between days 0 and 7. Three occurred in phenotypically G6PD deficient patients, two in AL and one in AL + PQ arm, but none in genotypically hemizygous/homozygous patients. All patients with acute haemolytic anaemia recovered without medical intervention. The findings support that the WHO recommendation of adding a single low-dose of PQ to standard AL regimen is safe for the treatment of acute uncomplicated P. falciparum malaria regardless of G6PD status in Tanzania. Trial registration number NCT02090036.

Comparison of azithromycin plus chloroquine versus artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in children in Africa: a randomized, open-label study.

PubMed

Chandra, Richa; Ansah, Patrick; Sagara, Issaka; Sie, Ali; Tiono, Alfred B; Djimde, Abdoulaye A; Zhao, Qinying; Robbins, Jeffery; Penali, Louis K; Ogutu, Bernhards

2015-03-10

This randomized, open-label study was conducted to establish the non-inferiority of a combination of azithromycin (AZ) and chloroquine (CQ) to artemether-lumefantrine (AL) for treatment of uncomplicated malaria in children from six sites in sub-Saharan Africa. Children with uncomplicated Plasmodium falciparum malaria between six and 59 months of age were randomized 1:1 to either AZCQ (30 mg/kg AZ + 10 mg/kg CQ base) or AL per prescribing information for three days (Days 0, 1, 2). Each site could enrol in the study population once the treatment of uncomplicated malaria in five children five to 12 years of age was deemed to be effective and well tolerated. The primary efficacy evaluation was the proportion of subjects in both the modified intent-to-treat (MITT) and per-protocol (PP) populations with an adequate clinical and parasitological response (PCR corrected) at Day 28. Non-inferiority was concluded if the lower bound of the 95% confidence interval comparing the two groups was 10 percentage points or greater. A total of 255 children were enrolled in the efficacy analysis (AZCQ, n = 124; AL, n = 131). The PCR corrected clearance rates were 89% (AZCQ) versus 98% (AL) for MITT, a difference of -9.10 (95% confidence interval; -16.02, -2.18) and 93% (AZCQ) versus 99% (AL) for PP, a difference of -6.08 (-12.10, -0.05). Early and late treatment failures were more common in subjects receiving AZCQ. Adverse events were more common in subjects treated with AZCQ. Drug concentrations obtained at specified time points following AZCQ administration had a large coefficient of variation partially due to sparse sampling with sample collection time window. In this study, non-inferiority of AZCQ to AL was not demonstrated. ClinicalTrials.gov NCT00677833 .

Effects of sevuparin on rosette formation and cytoadherence of Plasmodium falciparum infected erythrocytes

PubMed Central

Saiwaew, Somporn; Sritabal, Juntima; Piaraksa, Nattaporn; Keayarsa, Srisuda; Ruengweerayut, Ronnatrai; Utaisin, Chirapong; Sila, Patima; Niramis, Rangsan; Udomsangpetch, Rachanee; Charunwatthana, Prakaykaew; Pongponratn, Emsri; Pukrittayakamee, Sasithon; Leitgeb, Anna M.; Wahlgren, Mats; Lee, Sue J.; Day, Nicholas P. J.; White, Nicholas J.; Dondorp, Arjen M.; Chotivanich, Kesinee

2017-01-01

In severe falciparum malaria cytoadherence of parasitised red blood cells (PRBCs) to vascular endothelium (causing sequestration) and to uninfected red cells (causing rosette formation) contribute to microcirculatory flow obstruction in vital organs. Heparin can reverse the underlying ligand-receptor interactions, but may increase the bleeding risks. As a heparin-derived polysaccharide, sevuparin has been designed to retain anti-adhesive properties, while the antithrombin-binding domains have been eliminated, substantially diminishing its anticoagulant activity. Sevuparin has been evaluated recently in patients with uncomplicated falciparum malaria, and is currently investigated in a clinical trial for sickle cell disease. The effects of sevuparin on rosette formation and cytoadherence of Plasmodium falciparum isolates from Thailand were investigated. Trophozoite stages of P. falciparum-infected RBCs (Pf-iRBCs) were cultured from 49 patients with malaria. Pf-iRBCs were treated with sevuparin at 37°C and assessed in rosetting and in cytoadhesion assays with human dermal microvascular endothelial cells (HDMECs) under static and flow conditions. The proportion of Pf-iRBCs forming rosettes ranged from 6.5% to 26.0% (median = 12.2%). Rosetting was dose dependently disrupted by sevuparin (50% disruption by 250 μg/mL). Overall 57% of P. falciparum isolates bound to HDMECs under static conditions; median (interquartile range) Pf-iRBC binding was 8.5 (3.0–38.0) Pf-iRBCs/1000 HDMECs. Sevuparin in concentrations ≥ 100 μg/mL inhibited cytoadherence. Sevuparin disrupts P. falciparum rosette formation in a dose dependent manner and inhibits cytoadherence to endothelial cells. The data support assessment of sevuparin as an adjunctive treatment to the standard therapy in severe falciparum malaria. PMID:28249043

Cytokine-associated neutrophil extracellular traps and antinuclear antibodies in Plasmodium falciparum infected children under six years of age

PubMed Central

Baker, Virginia S; Imade, Godwin E; Molta, Norman B; Tawde, Pallavi; Pam, Sunday D; Obadofin, Michael O; Sagay, Soloman A; Egah, Daniel Z; Iya, Daniel; Afolabi, Bangmboye B; Baker, Murray; Ford, Karen; Ford, Robert; Roux, Kenneth H; Keller, Thomas CS

2008-01-01

Background In Plasmodium falciparum-infected children, the relationships between blood cell histopathology, blood plasma components, development of immunocompetence and disease severity remain poorly understood. Blood from Nigerian children with uncomplicated malaria was analysed to gain insight into these relationships. This investigation presents evidence for circulating neutrophil extracellular traps (NETs) and antinuclear IgG antibodies (ANA). The presence of NETs and ANA to double-stranded DNA along with the cytokine profiles found suggests autoimmune mechanisms that could produce pathogenesis in children, but immunoprotection in adults. Methods Peripheral blood smear slides and blood samples obtained from 21 Nigerian children under six years of age, presenting with uncomplicated malaria before and seven days after initiation of sulphadoxine-pyrimethamine (SP) treatment were analysed. The slides were stained with Giemsa and with DAPI. Levels of the pro-inflammatory cytokines IFN-γ, IL-2, TNF, CRP, and IL-6, select anti-inflammatory cytokines TGF-β and IL-10, and ANA were determined by immunoassay. Results The children exhibited circulating NETs with adherent parasites and erythrocytes, elevated ANA levels, a Th2 dominated cytokine profile, and left-shifted leukocyte differential counts. Nonspecific ANA levels were significant in 86% of the children pretreatment and in 100% of the children seven days after SP treatment, but in only 33% of age-matched control samples collected during the season of low parasite transmission. Levels of ANA specific for dsDNA were significant in 81% of the children both pre-treatment and post treatment. Conclusion The results of this investigation suggest that NET formation and ANA to dsDNA may induce pathology in falciparum-infected children, but activate a protective mechanism against falciparum malaria in adults. The significance of in vivo circulating chromatin in NETs and dsDNA ANA as a causative factor in the hyporesponsiveness of CpG oligonucleotide-based malaria vaccines is discussed. PMID:18312656

Levels and interactions of plasma xanthine oxidase, catalase and liver function parameters in Nigerian children with Plasmodium falciparum infection.

PubMed

Iwalokun, B A; Bamiro, S B; Ogunledun, A

2006-12-01

Elevated plasma levels of xanthine oxidase and liver function parameters have been associated with inflammatory events in several human diseases. While xanthine oxidase provides in vitro protection against malaria, its pathophysiological functions in vivo and interactions with liver function parameters remain unclear. This study examined the interactions and plasma levels of xanthine oxidase (XO) and uric acid (UA), catalase (CAT) and liver function parameters GOT, GPT and bilirubin in asymptomatic (n=20), uncomplicated (n=32), and severe (n=18) falciparum malaria children aged 3-13 years. Compared to age-matched control (n=16), significant (p<0.05) elevation in xanthine oxidase by 100-550%, uric acid by 15.4-153.8%, GOT and GPT by 22.1-102.2%, and total bilirubin by 2.3-86% according to parasitaemia (geometric mean parasite density (GMPD)=850-87100 parasites/microL) was observed in the malarial children. Further comparison with control revealed higher CAT level (16.2+/-0.5 vs 14.6+/-0.4 U/L; p<0.05) lacking significant (p>0.05) correlation with XO, but lower CAT level (13.4-5.4 U/L) with improved correlations (r=-0.53 to -0.91; p<0.05) with XO among the asymptomatic and symptomatic malaria children studied. 75% of control, 45% of asymptomatic, 21.9% of uncomplicated, and none of severe malaria children had Hb level>11.0 g/dL. Multivariate analyses further revealed significant (p<0.05) correlations between liver function parameters and xanthine oxidase (r=0.57-0.64) only in the severe malaria group. We conclude that elevated levels of XO and liver enzymes are biochemical features of Plasmodium falciparum parasitaemia in Nigerian children, with both parameters interacting differently to modulate the catalase response in asymptomatic and symptomatic falciparum malaria.

IgE low affinity receptor (CD23) expression, Plasmodium falciparum specific IgE and tumor necrosis factor-alpha production in Thai uncomplicated and severe falciparum malaria patients.

PubMed

Kumsiri, Ratchanok; Troye-Blomberg, Marita; Pattanapanyasat, Kovit; Krudsood, Srivicha; Maneerat, Yaowapa

2016-02-01

Previous studies have suggested that Plasmodium falciparum (P. falciparum) specific IgE in the form of immune complexes crosslinking the low-affinity receptor (CD23) on monocyte results in tumor necrosis factor (TNF)-α and nitric oxide (NO) production. However, the roles of these parameters in severity and immune protection are still unclear. This study aimed to determine the association between CD23 expression on monocytes, plasma soluble CD23 (sCD23), total IgE, malaria-specific IgE and IgG, and TNF-α levels in P. falciparum infected patients. We evaluated 64 uncomplicated (UC) and 25 severe patients (S), admitted at the Hospital for Tropical Diseases, Mahidol University, and 34 healthy controls (C) enrolled in 2001. Flow cytometry and enzyme linked immunosorbent assays (ELISA) demonstrated that trends of the CD23 expression, levels of sCD23 and specific IgE were higher in the S group as compared to those in the UC and C groups. Plasma levels of P. falciparum specific IgE in the UC (p=0.011) and S groups (p=0.025) were significantly higher than those in C group. In contrast the TNF-α levels tended to be higher in the UC than those in the S (p=0.343) and significantly higher than those in C (p=0.004) groups. The specific IgG levels in UC were significantly higher than those in S and C (p<0.001) groups. At admission, a strong significant negative correlation was found between specific IgG and sCD23 (r=-0.762, p=0.028), and TNF-α and IgE-IgG complexes (r=-0.715, p=0.002). Significant positive correlations between levels of specific IgE and TNF-α (r=0.575, p=0.010); and sCD23 (r=0.597, p=0.000) were also observed. In conclusion, our data suggest that CD23 expression and malaria-specific IgE levels may be involved in the severity of the disease while TNF-α and the malaria-specific IgG may correlate with protection against falciparum malaria. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Escalating Plasmodium falciparum antifolate drug resistance mutations in Macha, rural Zambia

PubMed Central

Mkulama, Mtawa AP; Chishimba, Sandra; Sikalima, Jay; Rouse, Petrica; Thuma, Philip E; Mharakurwa, Sungano

2008-01-01

Background In Zambia the first-line treatment for uncomplicated malaria is artemisinin combination therapy (ACT), with artemether-lumefantrine currently being used. However, the antifolate regimen, sulphadoxine-pyrimethamine (SP), remains the treatment of choice in children weighing less than 5 kg and also in expectant mothers. SP is also the choice drug for intermittent preventive therapy in pregnancy and serves as stand-by treatment during ACT stock outs. The current study assessed the status of Plasmodium falciparum point mutations associated with antifolate drug resistance in the area around Macha. Methods A representative sample of 2,780 residents from the vicinity of Macha was screened for malaria by microscopy. At the same time, blood was collected onto filter paper and dried for subsequent P. falciparum DNA analysis. From 188 (6.8%) individuals that were thick film-positive, a simple random sub-set of 95 P. falciparum infections were genotyped for DHFR and DHPS antifolate resistance mutations, using nested PCR and allele-specific restriction enzyme digestion. Results Plasmodium falciparum field samples exhibited a high prevalence of antifolate resistance mutations, including the DHFR triple (Asn-108 + Arg-59 + Ile-51) mutant (41.3%) and DHPS double (Gly-437 + Glu-540) mutant (16%). The quintuple (DHFR triple + DHPS double) mutant was found in 4 (6.5%) of the samples. Levels of mutated parasites showed a dramatic escalation, relative to previous surveys since 1988. However, neither of the Val-16 and Thr-108 mutations, which jointly confer resistance to cycloguanil, was detectable among the human infections. The Leu-164 mutation, associated with high grade resistance to both pyrimethamine and cycloguanil, as a multiple mutant with Asn-108, Arg-59 and (or) Ile-51, was also absent. Conclusion This study points to escalating levels of P. falciparum antifolate resistance in the vicinity of Macha. Continued monitoring is recommended to ensure timely policy revisions before widespread resistance exacts a serious public health toll. PMID:18495008

Escalating Plasmodium falciparum antifolate drug resistance mutations in Macha, rural Zambia.

PubMed

Mkulama, Mtawa A P; Chishimba, Sandra; Sikalima, Jay; Rouse, Petrica; Thuma, Philip E; Mharakurwa, Sungano

2008-05-21

In Zambia the first-line treatment for uncomplicated malaria is artemisinin combination therapy (ACT), with artemether-lumefantrine currently being used. However, the antifolate regimen, sulphadoxine-pyrimethamine (SP), remains the treatment of choice in children weighing less than 5 kg and also in expectant mothers. SP is also the choice drug for intermittent preventive therapy in pregnancy and serves as stand-by treatment during ACT stock outs. The current study assessed the status of Plasmodium falciparum point mutations associated with antifolate drug resistance in the area around Macha. A representative sample of 2,780 residents from the vicinity of Macha was screened for malaria by microscopy. At the same time, blood was collected onto filter paper and dried for subsequent P. falciparum DNA analysis. From 188 (6.8%) individuals that were thick film-positive, a simple random sub-set of 95 P. falciparum infections were genotyped for DHFR and DHPS antifolate resistance mutations, using nested PCR and allele-specific restriction enzyme digestion. Plasmodium falciparum field samples exhibited a high prevalence of antifolate resistance mutations, including the DHFR triple (Asn-108 + Arg-59 + Ile-51) mutant (41.3%) and DHPS double (Gly-437 + Glu-540) mutant (16%). The quintuple (DHFR triple + DHPS double) mutant was found in 4 (6.5%) of the samples. Levels of mutated parasites showed a dramatic escalation, relative to previous surveys since 1988. However, neither of the Val-16 and Thr-108 mutations, which jointly confer resistance to cycloguanil, was detectable among the human infections. The Leu-164 mutation, associated with high grade resistance to both pyrimethamine and cycloguanil, as a multiple mutant with Asn-108, Arg-59 and (or) Ile-51, was also absent. This study points to escalating levels of P. falciparum antifolate resistance in the vicinity of Macha. Continued monitoring is recommended to ensure timely policy revisions before widespread resistance exacts a serious public health toll.

Comparison of apoptosis in human primary pulmonary endothelial cells and a brain microvascular endothelial cell line co-cultured with Plasmodium falciparum field isolates.

PubMed

Essone, Jean Claude Biteghe Bi; N'Dilimabaka, Nadine; Ondzaga, Julien; Lekana-Douki, Jean Bernard; Mba, Dieudonné Nkoghe; Deloron, Philippe; Mazier, Dominique; Gay, Frédrérick; Touré Ndouo, Fousseyni S

2017-06-27

Plasmodium falciparum infection can progress unpredictably to severe forms including respiratory distress and cerebral malaria. The mechanisms underlying the variable natural course of malaria remain elusive. The cerebral microvascular endothelial cells-D3 and lung endothelial cells both from human were cultured separately and challenged with P. falciparum field isolates taken directly from malaria patients or 3D7 strain (in vitro maintained culture). The capacity of these P. falciparum isolates to induce endothelial cell apoptosis via cytoadherence or not was then assessed. Overall, 27 P. falciparum isolates were collected from patients with uncomplicated malaria (n = 25) or severe malaria (n = 2). About half the isolates (n = 17) were able to bind brain endothelial cells (12 isolates, 44%) or lung endothelial cells (17 isolates, 63%) or both (12 isolates, 44%). Sixteen (59%) of the 27 isolates were apoptogenic for brain and/or lung endothelial cells. The apoptosis stimulus could be cytoadherence, direct cell-cell contact without cytoadherence, or diffusible soluble factors. While some of the apoptogenic isolates used two stimuli (direct contact with or without cytoadherence, plus soluble factors) to induce apoptosis, others used only one. Among the 16 apoptogenic isolates, eight specifically targeted brain endothelial cells, one lung endothelial cells, and seven both. These results indicate that the brain microvascular cell line was more susceptible to apoptosis triggered by P. falciparum than the primary pulmonary endothelial cells and may have relevance to host-parasite interaction.

Prescriptions for uncomplicated malaria treatment among pregnant women in the Brazilian Amazon: evidences from the Mafalda Project.

PubMed

Luz, Tatiana Chama Borges; Miranda, Elaine Silva; Freitas, Letícia Figueira; Osório-de-Castro, Claudia Garcia Serpa

2013-06-01

To evaluate antimalarial prescriptions according to quality indicators and to describe adverse events reports among pregnant women with uncomplicated malaria. Descriptive study of medical files of pregnant women 15 years and older, residents in high-risk municipalities in the Brazilian Amazon. Antimalarial medicines were characterized by frequency of prescription, type of plasmodium and health care facilities where prescribing took place, and by possible adverse events. Variables were compared by Pearson's chi-square. A total of 262 medical files were evaluated. Most patients were diagnosed for Plasmodium vivax 71,2%. Chloroquine was the commonest prescribed antimalarial (65.6%). Of P. vivax prescriptions, 9.0%, and 16.2% of P. falciparum prescriptions presented antimalarials not recommended in the official protocol. Prescriptions for P. falciparum , in significantly higher proportion, did not adhere to the official protocol in regard to type of antimalarial and dose/duration of treatment (p = 0,001). They also lacked information on dose and dosing interval (p = 0,004). There were no significant differences among reference centers and basic health care units in respect to the prescribed antimalarials, to prescriptions containing antimalarials not recommended in the official protocol or in respect to lack of dosing information. Chloroquine was the antimalarial most related to the occurrence of adverse events. THE findings indicate that there are flaws in antimalarial prescribing for pregnant women, especially in respect to their adequacy to the official protocol.

Malaria rapid diagnostic tests in endemic settings.

PubMed

Maltha, J; Gillet, P; Jacobs, J

2013-05-01

Malaria rapid diagnostic tests (RDTs) are instrument-free tests that provide results within 20 min and can be used by community health workers. RDTs detect antigens produced by the Plasmodium parasite such as Plasmodium falciparum histidine-rich protein-2 (PfHPR2) and Plasmodium lactate dehydrogenase (pLDH). The accuracy of RDTs for the diagnosis of uncomplicated P. falciparum infection is equal or superior to routine microscopy (but inferior to expert microscopy). Sensitivity for Plasmodium vivax is 75-100%; for Plasmodium ovale and Plasmodium malariae, diagnostic performance is poor. Design limitations of RDTs include poor sensitivity at low parasite densities, susceptibility to the prozone effect (PfHRP2-detecting RDTs), false-negative results due to PfHRP2 deficiency in the case of pfhrp2 gene deletions (PfHRP2-detecting RDTs), cross-reactions between Plasmodium antigens and detection antibodies, false-positive results by other infections and susceptibility to heat and humidity. End-user's errors relate to safety, procedure (delayed reading, incorrect sample and buffer volumes) and interpretation (not recognizing invalid test results, disregarding faint test lines). Withholding antimalarial treatment in the case of negative RDT results tends to be infrequent and tendencies towards over-prescription of antibiotics have been noted. Numerous shortcomings in RDT kits' labelling, instructions for use (correctness and readability) and contents have been observed. The World Health Organization and partners actively address quality assurance of RDTs by comparative testing of RDTs, inspections of manufacturing sites, lot testing and training tools but no formal external quality assessment programme of end-user performance exists. Elimination of malaria requires RDTs with lower detection limits, for which nucleic acid amplification tests are under development. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

Adding a single low-dose of primaquine (0.25 mg/kg) to artemether-lumefantrine did not compromise treatment outcome of uncomplicated Plasmodium falciparum malaria in Tanzania: a randomized, single-blinded clinical trial.

PubMed

Mwaiswelo, Richard; Ngasala, Billy; Jovel, Irina; Aydin-Schmidt, Berit; Gosling, Roland; Premji, Zul; Mmbando, Bruno; Björkman, Anders; Mårtensson, Andreas

2016-08-26

The World Health Organization (WHO) recently recommended the addition of a single low-dose of the gametocytocidal drug primaquine (PQ) to artemisinin-based combination therapy (ACT) in low transmission settings as a component of pre-elimination or elimination programmes. However, it is unclear whether that influences the ACT cure rate. The study assessed treatment outcome of artemether-lumefantrine (AL) plus a single PQ dose (0.25 mg/kg) versus standard AL regimen for treatment of acute uncomplicated Plasmodium falciparum malaria in Tanzania. A randomized, single-blinded, clinical trial was conducted in Yombo, Bagamoyo district, Tanzania. Acute uncomplicated P. falciparum malaria patients aged ≥1 year, with the exception of pregnant and lactating women, were enrolled and treated with AL plus a single PQ dose (0.25 mg/kg) or AL alone under supervision. PQ was administered together with the first AL dose. Clinical and laboratory assessments were performed at 0, 8, 24, 36, 48, 60, and 72 h and on days 7, 14, 21, and 28. The primary end-point was a polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response (ACPR) on day 28. Secondary outcomes included: fever and asexual parasitaemia clearance, proportion of patients with PCR-determined parasitaemia on day 3, and proportion of patients with Pfmdr1 N86Y and Pfcrt K76T on days 0, 3 and day of recurrent infection. Overall 220 patients were enrolled, 110 were allocated AL + PQ and AL, respectively. Parasite clearance by microscopy was fast, but PCR detectable parasitaemia on day 3 was 31/109 (28.4 %) and 29/108 (26.9 %) in patients treated with AL + PQ and AL, respectively (p = 0.79). Day 28 PCR-adjusted ACPR and re-infection rate was 105/105 (100 %) and 101/102 (99 %) (p = 0.31), and 5/107 (4.7 %) and 5/8 (4.8 %) (p = 0.95), in AL + PQ and AL arm, respectively. There was neither any statistically significant difference in the proportion of Pfmdr1 N86Y or Pfcrt K76T between treatment arms on days 0, 3 and day of recurrent infection, nor within treatment arms between days 0 and 3 or day 0 and day of recurrent infection. The new WHO recommendation of adding a single low-dose of PQ to AL did not compromise treatment outcome of uncomplicated P. falciparum malaria in Tanzania. Trial registration number NCT02090036.

Reduced ex vivo susceptibility of Plasmodium falciparum after oral artemether-lumefantrine treatment in Mali.

PubMed

Dama, Souleymane; Niangaly, Hamidou; Ouattara, Amed; Sagara, Issaka; Sissoko, Sekou; Traore, Oumar Bila; Bamadio, Amadou; Dara, Niawanlou; Djimde, Moussa; Alhousseini, Mohamed Lamine; Goita, Siaka; Maiga, Hamma; Dara, Antoine; Doumbo, Ogobara K; Djimde, Abdoulaye A

2017-02-02

Artemisinin-based combination therapy is the recommended first-line treatment for uncomplicated falciparum malaria worldwide. However, recent studies conducted in Mali showed an increased frequency of recurrent parasitaemia following artemether-lumefantrine (AL) treatment. Study samples were collected during a large WANECAM study. Ex-vivo Plasmodium falciparum sensitivity to artemether and lumefantrine was assessed using the tritiated hypoxanthine-based assay. The prevalence of molecular markers of anti-malarial drug resistance (pfcrt K76T, pfmdr1 N86Y and K13-propeller) were measured by PCR and/or sequencing. Overall 61 samples were successfully analysed in ex vivo studies. Mean IC 50 s increased significantly between baseline and recurrent parasites for both artemether (1.6 nM vs 3.2 nM, p < 0.001) and lumefantrine (1.4 nM vs 3.4 nM, p = 0.004). Wild type Pfmdr1 N86 allele was selected after treatment (71 vs 91%, 112 of 158 vs 95 of 105, p < 0.001) but not the wild type pfcrt K76 variant (23.5 vs 24.8%, 40 of 170 vs 26 of 105, p = 0.9). Three non-synonymous K13-propeller SNPs (A522C, A578S, and G638R) were found with allele frequencies <2%. Malian post-AL P. falciparum isolates were less susceptible to artemether and lumefantrine than baseline isolates.

Antipyretic effect of ibuprofen in Gabonese children with uncomplicated falciparum malaria: a randomized, double-blind, placebo-controlled trial

PubMed Central

Matsiégui, Pierre-Blaise; Missinou, Michel A; Necek, Magdalena; Mavoungou, Elie; Issifou, Saadou; Lell, Bertrand; Kremsner, Peter G

2008-01-01

Background Antipyretic drugs are widely used in children with fever, though there is a controversy about the benefit of reducing fever in children with malaria. In order to assess the effect of ibuprofen on fever compared to placebo in children with uncomplicated Plasmodium falciparum malaria in Gabon, a randomized double blind placebo controlled trial, was designed. Methods Fifty children between two and seven years of age with uncomplicated malaria were included in the study. For the treatment of fever, all patients "received" mechanical treatment when the temperature rose above 37.5°C. In addition to the mechanical treatment, continuous fanning and cooling blanket, patients were assigned randomly to receive ibuprofen (7 mg/kg body weight, every eight hours) or placebo. Results The fever clearance time using a fever threshold of 37.5°C was similar in children receiving ibuprofen compared to those receiving placebo. The difference was also not statistically significant using a fever threshold of 37.8°C or 38.0°C. However, the fever time and the area under the fever curve were significantly smaller in the ibuprofen group compared to the placebo group. Conclusion Ibuprofen is effective in reducing the time with fever. The effect on fever clearance is less obvious and depends on definition of the fever threshold. Trial registration The trial registration number is: NCT00167713 PMID:18503714

Nonradioactive heteroduplex tracking assay for the detection of minority-variant chloroquine-resistant Plasmodium falciparum in Madagascar

PubMed Central

Juliano, Jonathan J; Randrianarivelojosia, Milijaona; Ramarosandratana, Benjamin; Ariey, Frédéric; Mwapasa, Victor; Meshnick, Steven R

2009-01-01

Background Strains of Plasmodium falciparum genetically resistant to chloroquine (CQ) due to the presence of pfcrt 76T appear to have been recently introduced to the island of Madagascar. The prevalence of such resistant genotypes is reported to be low (< 3%) when evaluated by conventional PCR. However, these methods are insensitive to low levels of mutant parasites present in patients with polyclonal infections. Thus, the current estimates may be an under representation of the prevalence of the CQ-resistant P. falciparum isolates on the island. Previously, minority variant chloroquine resistant parasites were described in Malawian patients using an isotopic heteroduplex tracking assay (HTA), which can detect pfcrt 76T-bearing P. falciparum minority variants in individual patients that were undetectable by conventional PCR. However, as this assay required a radiolabeled probe, it could not be used in many resource-limited settings. Methods This study describes a digoxigenin (DIG)-labeled chemiluminescent heteroduplex tracking assay (DIG-HTA) to detect pfcrt 76T-bearing minority variant P. falciparum. This assay was compared to restriction fragment length polymorphism (RFLP) analysis and to the isotopic HTA for detection of genetically CQ-resistant parasites in clinical samples. Results Thirty one clinical P. falciparum isolates (15 primary isolates and 16 recurrent isolates) from 17 Malagasy children treated with CQ for uncomplicated malaria were genotyped for the pfcrt K76T mutation. Two (11.7%) of 17 patients harboured genetically CQ-resistant P. falciparum strains after therapy as detected by HTA. RFLP analysis failed to detect any pfcrt K76T-bearing isolates. Conclusion These findings indicate that genetically CQ-resistant P. falciparum are more common than previously thought in Madagascar even though the fitness of the minority variant pfcrt 76T parasites remains unclear. In addition, HTAs for malaria drug resistance alleles are promising tools for the surveillance of anti-malarial resistance. The use of a non-radioactive label allows for the use of HTAs in malaria endemic countries. PMID:19291288

Clinical characteristics and disposition kinetics of the hepatomegaly associated with acute, uncomplicated, Plasmodium falciparum malaria in children.

PubMed

Sowunmi, A; Adedeji, A A; Sowunmi, C O; Falade, C O; Falade, A G; Ohaeri, B; Happi, T C; Oduola, A M

2001-01-01

The clinical characteristics and the kinetics of the disposition of the hepatomegaly associated with acute, uncomplicated Plasmodium falciparum malaria were investigated in 162 children in an endemic area of Nigeria. Hepatomegaly was significantly more common in the younger than in the older children. Complete resolution occurred in 48% following antimalarial chemotherapy. In the children in whom hepatomegaly did not resolve, a reduction in liver size of < 17% by the time parasitaemia was cleared (usually on day 3) was associated with non-resolution of hepatomegaly by days 7 or 14 of follow-up. An increase in liver size to at least 125% of the baseline value by day 4 or 5 was associated with a lack of therapeutic response, providing the child involved was aged < 5 years. In the children who had complete clearance of parasitaemia and resolution of hepatomegaly, there was no significant relationship between the parasitaemia-derived conventional indices of therapeutic response [i.e. time to clearance of 50% (PC50) or 90% (PC90) of the parasitaemia, and the parasite-clearance time (PCT)] and the corresponding parameters derived from measurement of liver size [i.e. time for resolution of 50% (HR50) or 90% (HR90) of the hepatomegaly and the hepatomegaly-resolution time (HRT)] in the same patients. However, as the HR50:PC50, HR90:PC90 and HRT:PCT ratios were similar (range = 1.6-2.1), the liver parameters may have therapeutic application. In the children with drug-sensitive P. falciparum infections and in whom hepatomegaly completely resolved, the area produced by plotting liver size against time (i.e. the area under the curve of hepatomegaly v. time, or AUChp) increased in proportion to the liver size below the costal margin (P = 0.02, from analysis of variance), but there was no significant difference in the half-lives of hepatomegaly (t1/2hp) or in the ratios of liver size to AUChp, indicating that the kinetics of the resolution of hepatomegaly were linear in the range examined. Comparison of the kinetic indices of hepatomegaly and parasitaemia showed that, although the half-lives of parasitaemia and hepatomegaly and the corresponding clearance values were similar, there was no correlation between these parameters among those in whom hepatomegaly completely resolved and parasitaemia completely cleared. These results indicate that routine clinical measurement of the liver size in children with hepatomegaly during acute, uncomplicated, P. falciparum malaria may have some use in evaluating and monitoring the therapeutic responses of infections. The resolution of hepatomegaly, a reflection of pathological changes, lags behind clearance of parasitaemia in children with P. falciparum malaria, and supports the use of the liver 'rate' as a malariometric index for assessing the intensity of transmission in endemic areas.

The Plasmodium berghei RC strain is highly diverged and harbors putatively novel drug resistance variants

PubMed Central

Kulawonganunchai, Supasak; Wilantho, Alisa; Koonyosying, Pongpisid; Uthaipibull, Chairat

2017-01-01

Background The current first line drugs for treating uncomplicated malaria are artemisinin (ART) combination therapies. However, Plasmodium falciparum parasites resistant to ART and partner drugs are spreading, which threatens malaria control efforts. Rodent malaria species are useful models for understanding antimalarial resistance, in particular genetic variants responsible for cross resistance to different compounds. Methods The Plasmodium berghei RC strain (PbRC) is described as resistant to different antimalarials, including chloroquine (CQ) and ART. In an attempt to identify the genetic basis for the antimalarial resistance trait in PbRC, its genome was sequenced and compared with five other previously sequenced P. berghei strains. Results We found that PbRC is eight-fold less sensitive to the ART derivative artesunate than the reference strain PbANKA. The genome of PbRC is markedly different from other strains, and 6,974 single nucleotide variants private to PbRC were identified. Among these PbRC private variants, non-synonymous changes were identified in genes known to modulate antimalarial sensitivity in rodent malaria species, including notably the ubiquitin carboxyl-terminal hydrolase 1 gene. However, no variants were found in some genes with strong evidence of association with ART resistance in P. falciparum such as K13 propeller protein. Discussion The variants identified in PbRC provide insight into P. berghei genome diversity and genetic factors that could modulate CQ and ART resistance in Plasmodium spp. PMID:29018598

Haemoglobin dynamics in Papuan and non-Papuan adults in northeast Papua, Indonesia, with acute, uncomplicated vivax or falciparum malaria

PubMed Central

2013-01-01

Background Haemoglobin (Hb) recovers slowly in malaria and may be influenced by naturally acquired immunity. Hb recovery was compared in malaria immune, indigenous Papuan and non-Papuan adults with limited malaria exposure. Methods Hb concentrations were measured on Days (D) 0, 3, 7, and 28 in 57 Papuans and 105 non-Papuans treated with chloroquine, doxycycline or both drugs for acute, uncomplicated Plasmodium vivax (n?=?64) or Plasmodium falciparum (n?=?98). Results Mean (SD, range) D0 Hb was 12.7 (2.2, 7–21.3) g/dL and was similar in P. falciparum infected Papuans and non-Papuans: 12.2 vs. 12.8 g/dL (P?=?0.15) but significantly lower in: (i) P. vivax-infected Papuans vs. P. vivax-infected non-Papuans: 11.4 vs. 13.47 g/dL [∆?=?−2.07 (95% CI: –3.3 – –0.8), P?=?0.0018], (ii) all patients with splenomegaly (vs. those without splenomegaly): 12.16 vs. 13.01 g/dL [∆?=?−0.85 (−1.6– –0.085), P?=?0.029], and (iii) all females vs. all males: 10.18 vs. 13.01 g/dL [∆?=?−2.82 (−3.97 – –1.67), P?

UK malaria treatment guidelines 2016.

PubMed

Lalloo, David G; Shingadia, Delane; Bell, David J; Beeching, Nicholas J; Whitty, Christopher J M; Chiodini, Peter L

2016-06-01

1.Malaria is the tropical disease most commonly imported into the UK, with 1300-1800 cases reported each year, and 2-11 deaths. 2. Approximately three quarters of reported malaria cases in the UK are caused by Plasmodium falciparum, which is capable of invading a high proportion of red blood cells and rapidly leading to severe or life-threatening multi-organ disease. 3. Most non-falciparum malaria cases are caused by Plasmodium vivax; a few cases are caused by the other species of plasmodium: Plasmodium ovale, Plasmodium malariae or Plasmodium knowlesi. 4. Mixed infections with more than one species of parasite can occur; they commonly involve P. falciparum with the attendant risks of severe malaria. 5. There are no typical clinical features of malaria; even fever is not invariably present. Malaria in children (and sometimes in adults) may present with misleading symptoms such as gastrointestinal features, sore throat or lower respiratory complaints. 6. A diagnosis of malaria must always be sought in a feverish or sick child or adult who has visited malaria-endemic areas. Specific country information on malaria can be found at http://travelhealthpro.org.uk/. P. falciparum infection rarely presents more than six months after exposure but presentation of other species can occur more than a year after exposure. 7. Management of malaria depends on awareness of the diagnosis and on performing the correct diagnostic tests: the diagnosis cannot be excluded until more than one blood specimen has been examined. Other travel related infections, especially viral haemorrhagic fevers, should also be considered. 8. The optimum diagnostic procedure is examination of thick and thin blood films by an expert to detect and speciate the malarial parasites. P. falciparum and P. vivax (depending upon the product) malaria can be diagnosed almost as accurately using rapid diagnostic tests (RDTs) which detect plasmodial antigens. RDTs for other Plasmodium species are not as reliable. 9. Most patients treated for P. falciparum malaria should be admitted to hospital for at least 24 h as patients can deteriorate suddenly, especially early in the course of treatment. In specialised units seeing large numbers of patients, outpatient treatment may be considered if specific protocols for patient selection and follow up are in place. 10. Uncomplicated P. falciparum malaria should be treated with an artemisinin combination therapy (Grade 1A). Artemether-lumefantrine (Riamet(®)) is the drug of choice (Grade 2C) and dihydroartemisinin-piperaquine (Eurartesim(®)) is an alternative. Quinine or atovaquone-proguanil (Malarone(®)) can be used if an ACT is not available. Quinine is highly effective but poorly-tolerated in prolonged treatment and should be used in combination with an additional drug, usually oral doxycycline. 11. Severe falciparum malaria, or infections complicated by a relatively high parasite count (more than 2% of red blood cells parasitized) should be treated with intravenous therapy until the patient is well enough to continue with oral treatment. Severe malaria is a rare complication of P. vivax or P. knowlesi infection and also requires parenteral therapy. 12. The treatment of choice for severe or complicated malaria in adults and children is intravenous artesunate (Grade 1A). Intravenous artesunate is unlicensed in the EU but is available in many centres. The alternative is intravenous quinine, which should be started immediately if artesunate is not available (Grade 1A). Patients treated with intravenous quinine require careful monitoring for hypoglycemia. 13. Patients with severe or complicated malaria should be managed in a high-dependency or intensive care environment. They may require haemodynamic support and management of: acute respiratory distress syndrome, disseminated intravascular coagulation, acute kidney injury, seizures, and severe intercurrent infections including Gram-negative bacteraemia/septicaemia. 14. Children with severe malaria should also be treated with empirical broad spectrum antibiotics until bacterial infection can be excluded (Grade 1B). 15. Haemolysis occurs in approximately 10-15% patients following intravenous artesunate treatment. Haemoglobin concentrations should be checked approximately 14 days following treatment in those treated with IV artemisinins (Grade 2C). 16. Falciparum malaria in pregnancy is more likely to be complicated: the placenta contains high levels of parasites, stillbirth or early delivery may occur and diagnosis can be difficult if parasites are concentrated in the placenta and scanty in the blood. 17. Uncomplicated falciparum malaria in the second and third trimester of pregnancy should be treated with artemether-lumefantrine (Grade 2B). Uncomplicated falciparum malaria in the first trimester of pregnancy should usually be treated with quinine and clindamycin but specialist advice should be sought. Severe malaria in any trimester of pregnancy should be treated as for any other patient with artesunate preferred over quinine (Grade 1C). 18. Children with uncomplicated malaria should be treated with an ACT (artemether-lumefantrine or dihydroartemisinin-piperaquine) as first line treatment (Grade 1A). Quinine with doxycycline or clindamycin, or atovaquone-proguanil at appropriate doses for weight can also be used. Doxycycline should not be given to children under 12 years. 19. Either an oral ACT or chloroquine can be used for the treatment of non-falciparum malaria. An oral ACT is preferred for a mixed infection, if there is uncertainty about the infecting species, or for P. vivax infection from areas where chloroquine resistance is common (Grade 1B). 20. Dormant parasites (hypnozoites) persist in the liver after treatment of P. vivax or P. ovale infection: the only currently effective drug for eradication of hypnozoites is primaquine (1A). Primaquine is more effective at preventing relapse if taken at the same time as chloroquine (Grade 1C). 21. Primaquine should be avoided or given with caution under expert supervision in patients with Glucose-6-phosphate dehydrogenase deficiency (G6PD), in whom it may cause severe haemolysis. 22. Primaquine (for eradication of P. vivax or P. ovale hypnozoites) is contraindicated in pregnancy and when breastfeeding (until the G6PD status of child is known); after initial treatment for these infections a pregnant woman should take weekly chloroquine prophylaxis until after delivery or cessation of breastfeeding when hypnozoite eradication can be considered. 23. An acute attack of malaria does not confer protection from future attacks: individuals who have had malaria should take effective anti-mosquito precautions and chemoprophylaxis during future visits to endemic areas. Copyright © 2016 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Plasmodium falciparum clearance in clinical studies of artesunate-amodiaquine and comparator treatments in sub-Saharan Africa, 1999–2009

PubMed Central

2014-01-01

Background Artemisinin-based combination therapy (ACT) is the recommended first-line therapy for uncomplicated Plasmodium falciparum malaria worldwide but decreased artemisinin susceptibility, phenotypically characterized as slow parasite clearance time (PCT), has now been reported in Southeast Asia. This makes it all too important to measure the dynamics of parasite clearance in African patients treated with ACT over time, to understand trends and detect changes early enough to intervene Methods Individual patient data from 27 clinical trials of artesunate-amodiaquine (ASAQ) vs comparators conducted between 1999 and 2009 were analysed for parasite clearance on modified intent-to-treat (ITT) basis. Results Overall 15,017 patients treated for uncomplicated P. falciparum malaria at 44 sites in 20 sub-Saharan African countries were included in the analysis; 51% (n=7,660) vs 49% (n=7,357) were treated with ASAQ and comparator treatments, respectively. Seventy-seven per cent (77%) were children under six years of age. The proportion of the patients treated with ASAQ with persistent parasitaemia on Day 2 was 8.6%, and 1.5% on Day 3. Risk factor for not clearing parasites on Day 2 and Day 3 calculated by multivariate logistic regression with random effect on site and controlling for treatment were: high parasitaemia before treatment was (adjusted risk ratios (AOR) 2.12, 95% CI 1.91-2.35, AOR 2.43, 95% CI 1.98-3.00, respectively); non-ACT treatment (p=0.001, for all comparisons). Anaemia (p=0.001) was an additional factor for Day 2 and young age (p=0.005) for Day 3. In patients treated with ASAQ in studies who had complete parasitaemia data every 24 hours up to Day 3 and additionally Day 7, the parasite reduction ratio was 93.9% by Day 1 and 99.9% by Day 2. Using the median parasitaemia before treatment (p0=27,125 μL) and a fitted model, the predicted PCT (pPCT = 3.614*ln (p0) – 6.135, r² = 0.94) in ASAQ recipients was 31 hours. Conclusion Within the period covered by these studies, rapid Plasmodium falciparum clearance continues to be achieved in Sub-Saharan African patients treated with ACT, and in particular with ASAQ. The prediction formula for parasite clearance time could be a pragmatic tool for studies with binary outcomes and once-daily sampling, both for research and monitoring purposes. PMID:24666562

Therapeutic efficacy and effects of artemisinin-based combination treatments on uncomplicated Plasmodium falciparum malaria -associated anaemia in Nigerian children during seven years of adoption as first-line treatments.

PubMed

Sowunmi, Akintunde; Akano, Kazeem; Ntadom, Godwin; Ayede, Adejumoke I; Ibironke, Folasade O; Aderoyeje, Temitope; Adewoye, Elsie O; Fatunmbi, Bayo; Oguche, Stephen; Okafor, Henrietta U; Watila, Ismaila; Meremikwu, Martin; Agomo, Philip; Ogala, William; Agomo, Chimere; Folarin, Onikepe A; Gbotosho, Grace O; Happi, Christian T

2017-02-07

Artemisinin-based combination treatments (ACTs) are the first-line treatments of uncomplicated Plasmodium falciparum malaria in many endemic areas but there are few evaluation of their efficacy in anaemic malarious children. Therapeutic efficacy of 3-day regimens of artesunate-amodiaquine and artemether-lumefantrine was evaluated in 437 anaemic and 909 non-anaemic malarious children following treatment during a seven-year period (2008-2014). Patterns of temporal changes in haematocrit were classified based on haematocrit values <30% and ≥30%. Kinetics of the disposition of the deficit in haematocrit from 30% following treatment were evaluated using a non-compartment model. PCR-corrected parasitological efficacy 28 days after start of treatment was significantly higher in artesunate-amodiaquine- compared to artemether-lumefantrine-treated children [97% (95%CI: 92.8-100) versus 96.4% (95%CI: 91.3-99.4), P = 0.02], but it was similar in non-anaemic and anaemic children. Fall in haematocrit/1 000 asexual parasites cleared from peripheral blood was significantly greater at lower compared to higher parasitaemias (P < 0.0001), and in non-anaemic compared to anaemic children (P = 0.007). In anaemic children at presentation, mean anaemia recovery time (AnRT) was 15.4 days (95%CI: 13.3-17.4) and it did not change over the years. Declines in haematocrit deficits from 30% were monoexponential with mean estimated half-time of 1.4 days (95%CI: 1.2-1.6). Anaemia half-time (t ½anaemia ) correlated positively with AnRT in the same patients (r = 0.69, P < 0.0001). Bland-Altman analysis of 10 multiples of t ½anaemia and AnRT showed narrow limit of agreement with insignificant bias (P = 0.07) suggesting both can be used interchangeably in the same patients. Artesunate-amodiaquine and artemether-lumefantrine remain efficacious treatments of uncomplicated P. falciparum infections in non-anaemic and anaemic Nigerian children in the last 7 years of adoption as first-line treatments. These ACTs may also conserve haematocrit at high parasitaemias and in anaemic children. Pan African Clinical Trial Registry PACTR201508001188143 , 3 July 2015; PACTR201510001189370 , 3 July 2015; PACTR201508001191898 , 7 July 2015 and PACTR201508001193368 , 8 July 2015.

Updated CDC Recommendations for Using Artemether-Lumefantrine for the Treatment of Uncomplicated Malaria in Pregnant Women in the United States.

PubMed

Ballard, Sarah-Blythe; Salinger, Allison; Arguin, Paul M; Desai, Meghna; Tan, Kathrine R

2018-04-13

Malaria infection during pregnancy is associated with an increased risk for maternal and fetal complications. In the United States, treatment options for uncomplicated, chloroquine-resistant Plasmodium falciparum and P. vivax malaria in pregnant women are limited to mefloquine or quinine plus clindamycin (1). However, limited availability of quinine and increasing resistance to mefloquine restrict these options. Strong evidence now demonstrates that artemether-lumefantrine (AL) (Coartem) is effective and safe in the treatment of malaria in pregnancy. The World Health Organization (WHO) has endorsed artemisinin-based combination therapies (ACTs), such as AL, for treatment of uncomplicated malaria during the second and third trimesters of pregnancy and is currently considering whether to add ACTs, including AL, as an option for malaria treatment during the first trimester (2,3). This policy note reviews the evidence and updates CDC recommendations to include AL as a treatment option for uncomplicated malaria during the second and third trimesters of pregnancy and during the first trimester of pregnancy when other treatment options are unavailable. These updated recommendations reflect current evidence and are consistent with WHO treatment guidelines.

High Levels of Plasmodium falciparum Rosetting in All Clinical Forms of Severe Malaria in African Children

PubMed Central

Doumbo, Ogobara K.; Thera, Mahamadou A.; Koné, Abdoulaye K.; Raza, Ahmed; Tempest, Louisa J.; Lyke, Kirsten E.; Plowe, Christopher V.; Rowe, J. Alexandra

2010-01-01

Plasmodium falciparum rosetting (the spontaneous binding of infected erythrocytes to uninfected erythrocytes) is a well-recognized parasite virulence factor. However, it is currently unclear whether rosetting is associated with all clinical forms of severe malaria, or only with specific syndromes such as cerebral malaria. We investigated the relationship between rosetting and clinical malaria in 209 Malian children enrolled in a case-control study of severe malaria. Rosetting was significantly higher in parasite isolates from severe malaria cases compared with non-severe hyperparasitemia and uncomplicated malaria controls (F2,117 = 8.15, P < 0.001). Analysis of sub-categories of severe malaria (unrousable coma, severe anemia, non-comatose neurological impairment, repeated seizures or a small heterogeneous group with signs of renal failure or jaundice) showed high levels of rosetting in all sub-categories, and no statistically significant differences in rosetting between sub-categories (F4,67 = 1.28, P = 0.28). Thus rosetting may contribute to the pathogenesis of all severe malaria syndromes in African children, and interventions to disrupt rosetting could be potential adjunctive therapies for all forms of severe malaria in Africa. PMID:19996426

The Severity of Plasmodium falciparum Infection Is Associated with Transcript Levels of var Genes Encoding Endothelial Protein C Receptor-Binding P. falciparum Erythrocyte Membrane Protein 1.

PubMed

Mkumbaye, Sixbert I; Wang, Christian W; Lyimo, Eric; Jespersen, Jakob S; Manjurano, Alphaxard; Mosha, Jacklin; Kavishe, Reginald A; Mwakalinga, Steven B; Minja, Daniel T R; Lusingu, John P; Theander, Thor G; Lavstsen, Thomas

2017-04-01

By attaching infected erythrocytes to the vascular lining, Plasmodium falciparum parasites leave blood circulation and avoid splenic clearance. This sequestration is central to pathogenesis. Severe malaria is associated with parasites expressing an antigenically distinct P. falciparum erythrocyte membrane protein 1 (PfEMP1) subset mediating binding to endothelial receptors. Previous studies indicate that PfEMP1 adhesins with so-called CIDRα1 domains capable of binding endothelial protein C receptor (EPCR) constitute the PfEMP1 subset associated with severe pediatric malaria. To analyze the relative importance of different subtypes of CIDRα1 domains, we compared Pf emp1 transcript levels in children with severe malaria (including 9 fatal and 114 surviving cases), children hospitalized with uncomplicated malaria ( n = 42), children with mild malaria not requiring hospitalization ( n = 10), and children with parasitemia and no ongoing fever ( n = 12). High levels of transcripts encoding EPCR-binding PfEMP1 were found in patients with symptomatic infections, and the abundance of these transcripts increased with disease severity. The compositions of CIDRα1 subtype transcripts varied markedly between patients, and none of the subtypes were dominant. Transcript-level analyses targeting other domain types indicated that subtypes of DBLβ or DBLζ domains might mediate binding phenomena that, in conjunction with EPCR binding, could contribute to pathogenesis. These observations strengthen the rationale for targeting the PfEMP1-EPCR interaction by vaccines and adjunctive therapies. Interventions should target EPCR binding of all CIDRα1 subtypes. Copyright © 2017 American Society for Microbiology.

Differences in Gene Transcriptomic Pattern of Plasmodium falciparum in Children with Cerebral Malaria and Asymptomatic Carriers

PubMed Central

Almelli, Talleh; Nuel, Grégory; Bischoff, Emmanuel; Aubouy, Agnès; Elati, Mohamed; Wang, Christian William; Dillies, Marie-Agnès; Coppée, Jean-Yves; Ayissi, Georges Nko; Basco, Leonardo Kishi; Rogier, Christophe; Ndam, Nicaise Tuikue; Deloron, Philippe; Tahar, Rachida

2014-01-01

The mechanisms underlying the heterogeneity of clinical malaria remain largely unknown. We hypothesized that differential gene expression contributes to phenotypic variation of parasites which results in a specific interaction with the host, leading to different clinical features of malaria. In this study, we analyzed the transcriptomes of isolates obtained from asymptomatic carriers and patients with uncomplicated or cerebral malaria. We also investigated the transcriptomes of 3D7 clone and 3D7-Lib that expresses severe malaria associated-variant surface antigen. Our findings revealed a specific up-regulation of genes involved in pathogenesis, adhesion to host cell, and erythrocyte aggregation in parasites from patients with cerebral malaria and 3D7-Lib, compared to parasites from asymptomatic carriers and 3D7, respectively. However, we did not find any significant difference between the transcriptomes of parasites from cerebral malaria and uncomplicated malaria, suggesting similar transcriptomic pattern in these two parasite populations. The difference between isolates from asymptomatic children and cerebral malaria concerned genes coding for exported proteins, Maurer's cleft proteins, transcriptional factor proteins, proteins implicated in protein transport, as well as Plasmodium conserved and hypothetical proteins. Interestingly, UPs A1, A2, A3 and UPs B1 of var genes were predominantly found in cerebral malaria-associated isolates and those containing architectural domains of DC4, DC5, DC13 and their neighboring rif genes in 3D7-lib. Therefore, more investigations are needed to analyze the effective role of these genes during malaria infection to provide with new knowledge on malaria pathology. In addition, concomitant regulation of genes within the chromosomal neighborhood suggests a common mechanism of gene regulation in P. falciparum. PMID:25479608

Current clinical efficacy of chloroquine for the treatment of Plasmodium falciparum infections in urban Dar es Salaam, United Republic of Tanzania.

PubMed Central

Premji, Z.; Makwaya, C.; Minjas, J. N.

1999-01-01

Reported is the use of a 14-day WHO protocol, which takes into account the clinical, parasitological and haematological responses to antimalarial drugs, to determine the efficacy of chloroquine in the treatment of uncomplicated malaria in young children (n = 200) in urban Dar es Salaam. Chloroquine failure was found in 43% of the children. Of these, 12.5% were considered to be early treatment failures and were given a single dose of sulfadoxine-pyrimethamine. Fever subsided in all children treated with sulfadoxine-pyrimethamine and there were no parasitological failures. In addition, children treated with sulfadoxine-pyrimethamine because of early treatment failure with chloroquine had better haematological recovery than the chloroquine-sensitive group. It is concluded that chloroquine can no longer be considered an effective therapy for P. falciparum malaria in young children in Dar es Salaam. PMID:10534897

Pro-inflammatory Cytokine Response and Genetic Diversity in Merozoite Surface Protein 2 of Plasmodium falciparum Isolates from Nigeria.

PubMed

Ajibaye, Olusola; Osuntoki, Akinniyi A; Ebuehi, Albert Ot; Iwalokun, Bamidele A; Balogun, Emmanuel O; Egbuna, Kathleen N

2017-01-01

Polymorphisms in Plasmodium falciparum merozoite surface protein-2 ( msp -2) and associated parasite genetic diversity which varies between malaria-endemic regions remain a limitation in malaria vaccine development. Pro-inflammatory cytokines are important in immunity against malaria, understanding the influence of genetic diversity on cytokine response is important for effective vaccine design. P. falciparum isolates obtained from 300 Nigerians with uncomplicated falciparum malaria at Ijede General Hospital, Ijede (IJE), General Hospital Ajeromi, Ajeromi (AJE) and Saint Kizito Mission Hospital, Lekki, were genotyped by nested polymerase chain reaction of msp -2 block 3 while ELISA was used to determine the pro-inflammatory cytokine response to describe the genetic diversity of P. falciparum . Eighteen alleles were observed for msp -2 loci. Of the 195 isolates, 61 (31.0%) had only FC27-type alleles, 38 (19.7%) had only 3D7-type alleles, and 49.3% had multiple parasite lines with both alleles. Band sizes were 275-625 bp for FC27 and 150-425 bp for 3D7. Four alleles were observed from LEK, 2 (375-425 bp) and 2 (275-325 bp) of FC27-and 3D7-types, respectively; 12 alleles from AJE, 9 (275-625 bp) and 3 (325-425 bp) of FC27-types and 3D7-types, respectively; while IJE had a total of 12 alleles, 9 (275-625 bp) and 3 (325-425 bp) of FC27-types and 3D7-types, respectively. Mean multiplicity of infection (MOI) was 1.54. Heterozygosity ( H E ) ranged from 0.77 to 0.87 and was highest for IJE (0.87). Cytokine response was higher among <5 years and was significantly associated with MOI ( P > 0.05) but with neither parasite density nor infection type. P. falciparum genetic diversity is extensive in Nigeria, protection via pro-inflammatory cytokines have little or no interplay with infection multiplicity.

A Phase 3, Double-Blind, Randomized Study of Arterolane Maleate–Piperaquine Phosphate vs Artemether–Lumefantrine for Falciparum Malaria in Adolescent and Adult Patients in Asia and Africa

PubMed Central

Toure, Offianan Andre; Valecha, Neena; Tshefu, Antoinette K.; Thompson, Ricardo; Krudsood, Srivicha; Gaye, Oumar; Rao, Bappanaidu Hoigegudde Krishnamurthy; Sagara, Issaka; Bose, Tarit Kumar; Mohanty, Sanjib; Rao, Ballamudi Srinivas; Anvikar, Anupkumar R.; Mwapasa, Victor; Noedl, Harald; Arora, Sudershan; Roy, Arjun; Iyer, Sunil S.; Sharma, Pradeep; Saha, Nilanjan; Jalali, Rajinder K.

2016-01-01

Background. Artemisinins, which are derived from plants, are subject to risk of supply interruption due to climatic changes. Consequently, an effort to identify a new synthetic antimalarial was initiated. A fixed-dose combination of arterolane maleate (AM), a new synthetic trioxolane, with piperaquine phosphate (PQP), a long half-life bisquinoline, was evaluated in patients with uncomplicated Plasmodium falciparum malaria. Methods. In this multicenter, randomized, double-blind, comparative, parallel-group trial, 1072 patients aged 12–65 years with P. falciparum monoinfection received either AM–PQP (714 patients) once daily or artemether–lumefantrine (A–L; 358 patients) twice daily for 3 days. All patients were followed up until day 42. Results. Of the 714 patients in the AM–PQP group, 638 (89.4%) completed the study; of the 358 patients in the A–L group, 301(84.1%) completed the study. In both groups, the polymerase chain reaction corrected adequate clinical and parasitological response (PCR–corrected ACPR) on day 28 in intent-to-treat (ITT) and per-protocol (PP) populations was 92.86% and 92.46% and 99.25% and 99.07%, respectively. The corresponding figures on day 42 in the ITT and PP populations were 90.48% and 91.34%, respectively. After adjusting for survival ITT, the PCR-corrected ACPR on day 42 was >98% in both groups. The overall incidence of adverse events was comparable. Conclusions. AM–PQP showed comparable efficacy and safety to A–L in the treatment of uncomplicated P. falciparum malaria in adolescent and adult patients. AM–PQP demonstrated high clinical and parasitological response rates as well as rapid parasite clearance. Clinical Trials Registration. India. CTRI/2009/091/000101. PMID:26908796

Rapid diagnostic tests for diagnosing uncomplicated non-falciparum or Plasmodium vivax malaria in endemic countries.

PubMed

Abba, Katharine; Kirkham, Amanda J; Olliaro, Piero L; Deeks, Jonathan J; Donegan, Sarah; Garner, Paul; Takwoingi, Yemisi

2014-12-18

In settings where both Plasmodium vivax and Plasmodium falciparum infection cause malaria, rapid diagnostic tests (RDTs) need to distinguish which species is causing the patients' symptoms, as different treatments are required. Older RDTs incorporated two test lines to distinguish malaria due to P. falciparum, from malaria due to any other Plasmodium species (non-falciparum). These RDTs can be classified according to which antibodies they use: Type 2 RDTs use HRP-2 (for P. falciparum) and aldolase (all species); Type 3 RDTs use HRP-2 (for P. falciparum) and pLDH (all species); Type 4 use pLDH (fromP. falciparum) and pLDH (all species).More recently, RDTs have been developed to distinguish P. vivax parasitaemia by utilizing a pLDH antibody specific to P. vivax. To assess the diagnostic accuracy of RDTs for detecting non-falciparum or P. vivax parasitaemia in people living in malaria-endemic areas who present to ambulatory healthcare facilities with symptoms suggestive of malaria, and to identify which types and brands of commercial test best detect non-falciparum and P. vivax malaria. We undertook a comprehensive search of the following databases up to 31 December 2013: Cochrane Infectious Diseases Group Specialized Register; MEDLINE; EMBASE; MEDION; Science Citation Index; Web of Knowledge; African Index Medicus; LILACS; and IndMED. Studies comparing RDTs with a reference standard (microscopy or polymerase chain reaction) in blood samples from a random or consecutive series of patients attending ambulatory health facilities with symptoms suggestive of malaria in non-falciparum endemic areas. For each study, two review authors independently extracted a standard set of data using a tailored data extraction form. We grouped comparisons by type of RDT (defined by the combinations of antibodies used), and combined in meta-analysis where appropriate. Average sensitivities and specificities are presented alongside 95% confidence intervals (95% CI). We included 47 studies enrolling 22,862 participants. Patient characteristics, sampling methods and reference standard methods were poorly reported in most studies. RDTs detecting 'non-falciparum' parasitaemiaEleven studies evaluated Type 2 tests compared with microscopy, 25 evaluated Type 3 tests, and 11 evaluated Type 4 tests. In meta-analyses, average sensitivities and specificities were 78% (95% CI 73% to 82%) and 99% (95% CI 97% to 99%) for Type 2 tests, 78% (95% CI 69% to 84%) and 99% (95% CI 98% to 99%) for Type 3 tests, and 89% (95% CI 79% to 95%) and 98% (95% CI 97% to 99%) for Type 4 tests, respectively. Type 4 tests were more sensitive than both Type 2 (P = 0.01) and Type 3 tests (P = 0.03).Five studies compared Type 3 tests with PCR; in meta-analysis, the average sensitivity and specificity were 81% (95% CI 72% to 88%) and 99% (95% CI 97% to 99%) respectively. RDTs detecting P.vivax parasitaemiaEight studies compared pLDH tests to microscopy; the average sensitivity and specificity were 95% (95% CI 86% to 99%) and 99% (95% CI 99% to 100%), respectively. RDTs designed to detect P. vivax specifically, whether alone or as part of a mixed infection, appear to be more accurate than older tests designed to distinguish P. falciparum malaria from non-falciparum malaria. Compared to microscopy, these tests fail to detect around 5% ofP. vivax cases. This Cochrane Review, in combination with other published information about in vitro test performance and stability in the field, can assist policy-makers to choose between the available RDTs.

Drug Evaluation in the Plasmodium Falciparum-Aotus Model.

DTIC Science & Technology

1986-09-30

strains of Plasmodium falciparum, Uganda Palo Alto ( chloroquine sensi- tive) or Vietnam Smith (chioroquine resistant), in Aotus trivirgatus, were used...Plasmodium falciparum in the Panamanian owl monkey Aotus Two strains of falciparum malaria, Uganda Palo Alto (sensitive to chloroquine anfd quinine...resistant to pyrimetha- mine) and Vietnam Smith (resistant to chloroquine , quinine and pyrimethamine) were used. Previous evaluation of two stereoisomers of

Loss of Humoral and Cellular Immunity to Invasive Nontyphoidal Salmonella during Current or Convalescent Plasmodium falciparum Infection in Malawian Children

PubMed Central

Nyirenda, James T.; Tembo, Dumizulu L.; Storm, Janet; Dube, Queen; Msefula, Chisomo L.; Jambo, Kondwani C.; Mwandumba, Henry C.; Heyderman, Robert S.; Gordon, Melita A.

2017-01-01

ABSTRACT Invasive nontyphoidal Salmonella (iNTS) infections are commonly associated with Plasmodium falciparum infections, but the immunologic basis for this linkage is poorly understood. We hypothesized that P. falciparum infection compromises the humoral and cellular immunity of the host to NTS, which increases the susceptibility of the host to iNTS infection. We prospectively recruited children aged between 6 and 60 months at a Community Health Centre in Blantyre, Malawi, and allocated them to the following groups; febrile with uncomplicated malaria, febrile malaria negative, and nonfebrile malaria negative. Levels of Salmonella enterica serovar Typhimurium-specific serum bactericidal activity (SBA) and whole-blood bactericidal activity (WBBA), complement C3 deposition, and neutrophil respiratory burst activity (NRBA) were measured. Levels of SBA with respect to S. Typhimurium were reduced in febrile P. falciparum-infected children (median, −0.20 log10 [interquartile range {IQR}, −1.85, 0.32]) compared to nonfebrile malaria-negative children (median, −1.42 log10 [IQR, −2.0, −0.47], P = 0.052). In relation to SBA, C3 deposition on S. Typhimurium was significantly reduced in febrile P. falciparum-infected children (median, 7.5% [IQR, 4.1, 15.0]) compared to nonfebrile malaria-negative children (median, 29% [IQR, 11.8, 48.0], P = 0.048). WBBA with respect to S. Typhimurium was significantly reduced in febrile P. falciparum-infected children (median, 0.25 log10 [IQR, −0.73, 1.13], P = 0.0001) compared to nonfebrile malaria-negative children (median, −1.0 log10 [IQR, −1.68, −0.16]). In relation to WBBA, S. Typhimurium-specific NRBA was reduced in febrile P. falciparum-infected children (median, 8.8% [IQR, 3.7, 20], P = 0.0001) compared to nonfebrile malaria-negative children (median, 40.5% [IQR, 33, 65.8]). P. falciparum infection impairs humoral and cellular immunity to S. Typhimurium in children during malaria episodes, which may explain the increased risk of iNTS observed in children from settings of malaria endemicity. The mechanisms underlying humoral immunity impairment are incompletely understood and should be explored further. PMID:28515136

Loss of Humoral and Cellular Immunity to Invasive Nontyphoidal Salmonella during Current or Convalescent Plasmodium falciparum Infection in Malawian Children.

PubMed

Nyirenda, Tonney S; Nyirenda, James T; Tembo, Dumizulu L; Storm, Janet; Dube, Queen; Msefula, Chisomo L; Jambo, Kondwani C; Mwandumba, Henry C; Heyderman, Robert S; Gordon, Melita A; Mandala, Wilson L

2017-07-01

Invasive nontyphoidal Salmonella (iNTS) infections are commonly associated with Plasmodium falciparum infections, but the immunologic basis for this linkage is poorly understood. We hypothesized that P. falciparum infection compromises the humoral and cellular immunity of the host to NTS, which increases the susceptibility of the host to iNTS infection. We prospectively recruited children aged between 6 and 60 months at a Community Health Centre in Blantyre, Malawi, and allocated them to the following groups; febrile with uncomplicated malaria, febrile malaria negative, and nonfebrile malaria negative. Levels of Salmonella enterica serovar Typhimurium-specific serum bactericidal activity (SBA) and whole-blood bactericidal activity (WBBA), complement C3 deposition, and neutrophil respiratory burst activity (NRBA) were measured. Levels of SBA with respect to S Typhimurium were reduced in febrile P. falciparum -infected children (median, -0.20 log10 [interquartile range {IQR}, -1.85, 0.32]) compared to nonfebrile malaria-negative children (median, -1.42 log10 [IQR, -2.0, -0.47], P = 0.052). In relation to SBA, C3 deposition on S Typhimurium was significantly reduced in febrile P. falciparum -infected children (median, 7.5% [IQR, 4.1, 15.0]) compared to nonfebrile malaria-negative children (median, 29% [IQR, 11.8, 48.0], P = 0.048). WBBA with respect to S Typhimurium was significantly reduced in febrile P. falciparum -infected children (median, 0.25 log10 [IQR, -0.73, 1.13], P = 0.0001) compared to nonfebrile malaria-negative children (median, -1.0 log10 [IQR, -1.68, -0.16]). In relation to WBBA, S Typhimurium-specific NRBA was reduced in febrile P. falciparum -infected children (median, 8.8% [IQR, 3.7, 20], P = 0.0001) compared to nonfebrile malaria-negative children (median, 40.5% [IQR, 33, 65.8]). P. falciparum infection impairs humoral and cellular immunity to S Typhimurium in children during malaria episodes, which may explain the increased risk of iNTS observed in children from settings of malaria endemicity. The mechanisms underlying humoral immunity impairment are incompletely understood and should be explored further. Copyright © 2017 Nyirenda et al.

Cytokine profiles among patients co-infected with Plasmodium falciparum malaria and soil borne helminths attending Kampala International University Teaching Hospital, in Uganda.

PubMed

Bwanika, Richard; Kato, Charles D; Welishe, Johnson; Mwandah, Daniel C

2018-01-01

Malaria and helminths share the same geographical distribution in tropical Africa. Studies of the interaction of helminth and malaria co-infection in humans have been few and are mainly epidemiological, with little information on cellular immune responses. This study aimed to determine Cytokine profiles among patients co-infected with Plasmodium falciparum malaria and soil borne helminth attending Kampala International University Teaching Hospital (KIU). A case control study of 240 patients were recruited at KIU teaching hospital. Patients with Plasmodium falciparum malaria were 55 (22.9%) and those with soil-borne helminths were 63 (26.3%). The controls were 89 (37.1%), while those co-infected with Plasmodium falciparum malaria and soil-borne helminths were 33 (13.8%). Cases were defined as having a positive blood smear for P. falciparum malaria, those with helminths or co-infections of the two. Negative controls were those with a negative blood smear for P. falciparum malaria and those with no stool parasitic infections. Patients presenting with signs and symptoms of malaria or those suspected of having helminths were recruited for the study. A panel of five cytokines (IFN-γ, TNF-α, IL-6, TGF-β and IL-10) were assayed from plasma samples in patients with and without Plasmodium falciparum malaria, patients with and without helminth, and then those co-infected with the two diseases diagnosis was done using thick blood smears stained with 10% Giemsa and stool examination was done following the Kato Katz technique following standard procedures. The prevalence of Plasmodium falciparum malaria by sex was 28 (11.7%) and 27 (11.3%) in male and female respectively. The overall prevalence of soil borne helminth was 26.3%, and among those harbouring helminths, 13.8% were co-infected with Plasmodium falciparum. Cytokine levels significantly differed across Plasmodium falciparum malaria, soil borne helminth infected patients and health controls for IFN-γ (P = 0.023), IL-10 (P = 0.008) and TGF-β (P = 0.0001). Cytokine levels significantly differed across Plasmodium falciparum malaria, soil borne helminth infected patients and patients co-infected with Plasmodium falciparum malaria and soil borne helminth for IL-10 (P = 0.004), IL-6 (P = 0.011) and TGF-β (P = 0.003). An up-regulation of IFN-γ during Plasmodium falciparum malaria and an up-regulation of IL-10 and TGF-β in soil borne helminth infections was demonstrated. We demonstrate that co-infections of Plasmodium falciparum and soil borne helminth lead to an up-regulation of IL-10 and IL-6 and a down-regulation of TGF-β. Trial registration No17/10-16.

Retinal Changes in Uncomplicated and Severe Plasmodium knowlesi Malaria.

PubMed

Govindasamy, Gayathri; Barber, Bridget E; Ghani, Shuaibah A; William, Timothy; Grigg, Matthew J; Borooah, Shyamanga; Dhillon, Bal; Dondorp, Arjen M; Yeo, Tsin W; Anstey, Nicholas M; Maude, Richard J

2016-05-01

Plasmodium knowlesi causes severe malaria, but its pathogenesis is poorly understood. Retinal changes provide insights into falciparum malaria pathogenesis but have not been studied in knowlesi malaria. An observational study was conducted in Malaysian adults hospitalized with severe (n = 20) and nonsevere (n = 24) knowlesi malaria using indirect ophthalmoscopy (n = 44) and fundus photography (n = 29). The patients' median age was 44 years (range, 18-74 years). No coma or deaths occurred. Photography detected retinal changes in 11 of 12 patients (92%) with severe and 14 of 17 (82%) with nonsevere knowlesi malaria. Nonspecific retinal whitening occurred in 3 (35%) and 5 (29%) patients with severe and nonsevere disease, respectively; hemorrhages in 2 (17%) and 3 (18%); loss of retinal pigment epithelium in 1 (8%) and 4 (24%); and drusen in 9 (71%) and 12 (75%). All changes were mild, with no significant differences between severe and nonsevere disease. Patients with retinal hemorrhages had lower platelet counts than those without (median, 22 vs 43 × 10(9)/L; P= .04). The paucity of specific retinal findings associated with disease severity in knowlesi malaria contrasts with the retinopathy of severe adult falciparum malaria with and without coma, suggesting that falciparum-like microvascular sequestration in the brain is not a major component in severe knowlesi malaria pathogenesis. © The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Novel Mutation in Cytochrome B of Plasmodium falciparum in One of Two Atovaquone-Proguanil Treatment Failures in Travelers Returning From Same Site in Nigeria

PubMed Central

Plucinski, Mateusz M.; Huber, Curtis S.; Akinyi, Sheila; Dalton, Willard; Eschete, Mary; Grady, Katharine; Silva-Flannery, Luciana; Mathison, Blaine A.; Udhayakumar, Venkatachalam; Arguin, Paul M.; Barnwell, John W.

2014-01-01

Background  Atovaquone-proguanil (AP) is the most commonly used treatment for uncomplicated Plasmodium falciparum malaria in the United States. Apparent AP treatment failures were reported 7 months apart in 2 American travelers who stayed in the same compound for foreign workers in Rivers State, Nigeria. Methods  We analyzed pretreatment (day 0) and day of failure samples from both travelers for mutations in the P falciparum cytochrome B (pfcytb) and dihydrofolate reductase (pfdhfr) genes associated with resistance to atovaquone and cycloguanil, the active metabolite of proguanil, respectively. We genotyped the parasites and sequenced their mitochondrial genomes. Results  On day 0, both travelers had proguanil-resistant genotypes but atovaquone-sensitive cytb sequences. Day of failure samples exhibited mutations in cytb for both travelers. One traveler had the common Y268S mutation, whereas the other traveler had a previously unreported mutation, I258M. The travelers had unrelated parasite genotypes and different mitochondrial genomes. Conclusions  Despite the infections likely having been contracted in the same site, there is no evidence that the cases were related. The mutations likely arose independently during the acute infection or treatment. Our results highlight the importance of genotyping parasites and sequencing the full cytb and dhfr genes in AP failures to rule out transmission of AP-resistant strains and identify novel mechanisms of AP resistance. PMID:25734129

Clinical implications of asymptomatic Plasmodium falciparum infections in Malawi.

PubMed

Buchwald, Andrea G; Sixpence, Alick; Chimenya, Mabvuto; Damson, Milius; Sorkin, John D; Wilson, Mark L; Seydel, Karl; Hochman, Sarah; Mathanga, Don P; Taylor, Terrie E; Laufer, Miriam K

2018-05-16

Asymptomatic Plasmodium falciparum infections are common in Malawi, however, the implications of these infections for the burden of malaria illness are unknown. Whether asymptomatic infections eventually progress to malaria illness, persist without causing symptoms, or clear spontaneously remains undetermined. We identified asymptomatic infections and evaluated the associations between persistent asymptomatic infections and malaria illness. Children and adults (N = 120) who presented at a health facility with uncomplicated malaria were followed monthly for two years. During follow-up visits, participants with malaria symptoms were tested and treated if positive. Samples from all visits were tested for parasites using both microscopy and PCR, and all malaria infections underwent genotyping. Cox frailty models were used to estimate the temporal association between asymptomatic infections and malaria illness episodes. Mixed models were used to estimate the odds of clinical symptoms associated with new versus persistent infections. Participants had a median follow-up time of 720 days. Asymptomatic infections were detected during 23% of visits. Persistent asymptomatic infections were associated with decreased risk of malaria illness in all ages (HR 0.50, p < 0.001). When asymptomatic infections preceded malaria illness, newly acquired infections were detected at 92% of subsequent clinical episodes, independent of presence of persistent infections. Malaria illness among children was more likely due to newly acquired infections (OR 1.4, 95%CI 1.3-1.5) than to persistent infections. Asymptomatic P. falciparum infections are associated with decreased incidence of malaria illness but do not protect against disease when new infection occurs.

Influence of host factors and parasite biomass on the severity of imported Plasmodium falciparum malaria

PubMed Central

Kendjo, Eric; Augé-Courtoi, Claire; Cojean, Sandrine; Clain, Jérôme; Houzé, Pascal; Thellier, Marc; Hubert, Veronique; Deloron, Philippe; Houzé, Sandrine

2017-01-01

Objectives Imported malaria in France is characterized by various clinical manifestations observed in a heterogeneous population of patients such as travelers/expatriates and African migrants. In this population, host factors and parasite biomass associated with severe imported malaria are poorly known. Methods From data collected by the Centre National de Référence du Paludisme, we identified epidemiological, demographic and biological features including parasite biomass and anti-plasmodial antibody levels (negative, positive and strongly positive serology) associated with different disease severity groups (very severe, moderately severe, and uncomplicated malaria) in 3 epidemiological groups (travelers/expatriates, first- and second-generation migrants). Results Age, ethnicity, absence of prior infection with P. falciparum, antibody levels, plasma PfHRP2 levels, total and circulating parasite biomass were related to severe malaria onset. Sequestered parasite biomass tended to be increased in very severe malaria, and was strongly correlated to the antibody level of the host. Conclusions Prior exposure to P. falciparum is associated with high anti-plasmodial antibody levels which influence clinical presentation of imported malaria and its correlated circulating and sequestered parasite burden. PMID:28410415

Efficacy and safety of fixed dose combination of arterolane maleate and piperaquine phosphate dispersible tablets in paediatric patients with acute uncomplicated Plasmodium falciparum malaria: a phase II, multicentric, open-label study.

PubMed

Toure, Offianan Andre; Rulisa, Stephen; Anvikar, Anupkumar R; Rao, Ballamudi S; Mishra, Pitabas; Jalali, Rajinder K; Arora, Sudershan; Roy, Arjun; Saha, Nilanjan; Iyer, Sunil S; Sharma, Pradeep; Valecha, Neena

2015-11-25

The World Health Organization (WHO) recommends artemisinin combination therapy (ACT) for the treatment of uncomplicated Plasmodium falciparum malaria. The present study investigated the efficacy and safety of fixed dose combination (FDC) of arterolane maleate 37.5 mg and piperaquine phosphate (PQP) 187.5 mg dispersible tablets in paediatric patients aged 6 months to 12 years. Male and female patients aged 6 months to 12 years who were confirmed cases of P. falciparum mono-infection with fever or documented history of fever in the previous 24 h were included. The patients were administered FDC of arterolane maleate and PQP as single daily doses for three consecutive days based on their age. The primary efficacy outcome was proportion of patients with polymerase chain reaction (PCR)-corrected adequate clinical and parasitological response (ACPR) on day 28. Safety was analysed based on adverse events (AE), laboratory abnormalities and abnormalities on electrocardiograph. A total of 141 eligible paediatric patients received FDC of arterolane maleate and PQP in a 42-day follow-up study. All the enrolled patients (141) were included in intention to treat (ITT) and safety analyses, and 126 patients were considered in per protocol (PP) population. The PCR-corrected ACPR on day 28 was achieved in all patients (100 %; 95 % CI 97.11-100) included in PP population. The median parasite clearance time (PCT) and fever clearance time (FCT) were 24 h (95 % CI 18.0-24.0) and 10 h (95 % CI 4.0-18.0), respectively. The most frequently reported clinical AE was vomiting. Majority of the AEs were mild to moderate in severity and resolved without sequelae. No patient was discontinued for any QTc (corrected QT interval) prolongation. No deaths or serious AEs were reported during the study. The findings from this study showed that FDC of arterolane maleate and PQP effectively cures P. falciparum malaria and attains acceptable level of cure by day 28 in paediatric patients. The efficacy and safety results observed in children warrants further studies on FDC of arterolane maleate and PQP dispersible tablets. Clinical Trial Registry India: CTRI/2009/091/000531.

In vitro piperaquine susceptibility is not associated with the Plasmodium falciparum chloroquine resistance transporter gene

PubMed Central

2013-01-01

Background Dihydroartemisinin-piperaquine is a new ACT that is administered as single daily dose for three days and has been demonstrated to be tolerated and highly effective for the treatment of uncomplicated Plasmodium falciparum malaria. Piperaquine was used alone to replace chloroquine as the first-line treatment for uncomplicated malaria in China in response to increasing chloroquine resistance in the 1970s. However, the rapid emergence of piperaquine-resistant strains that resulted in the cessation of its use in China in the 1980s, suggests that there is cross-resistance between piperaquine and chloroquine. Very few data are available on cross-resistance between piperaquine and chloroquine, and the data that do exist are often contradictory. Methods In total, 280 P. falciparum isolates, collected between April 2008 and June 2012 from patients hospitalized in France with imported malaria from a malaria-endemic country, were assessed ex vivo for piperaquine and chloroquine susceptibilities by using the standard 42-hour 3H-hypoxanthine uptake inhibition method. The chloroquine resistance-associated mutation K76T in pfcrt was also investigated for the 280 isolates. Results The IC50 for piperaquine ranged from 9.8 nM to 217.3 nM (mean = 81.3 nM. The IC50 for chloroquine ranged from 5.0 nM to 1,918 nM (mean = 83.6 nM. A significant but low correlation was observed between the Log IC50 values for piperaquine and chloroquine (r = 0.145, p < 0.001). However, the coefficient of determination of 0.021 indicates that only 2.1% of the variation in the response to piperaquine is explained by the variation in the response to chloroquine. The mean value for piperaquine was 74.0 nM in the Pfcrt K76 wild-type group (no = 125) and 87.7 nM in the 76 T mutant group (no = 155). This difference was not significant (p = 0.875, Mann Whitney U test). Conclusions The present work demonstrates that there was no cross-resistance between piperaquine and chloroquine among 280 P. falciparum isolates and that piperaquine susceptibility is not associated with pfcrt, the gene involved in chloroquine resistance. These results confirm the efficacy of piperaquine in association with dihydroartemisinin and support its use in areas in which parasites are resistant to chloroquine. PMID:24274185

Evaluation of FRET real-time PCR assay for rapid detection and differentiation of Plasmodium species in returning travellers and migrants

PubMed Central

Safeukui, Innocent; Millet, Pascal; Boucher, Sébastien; Melinard, Laurence; Fregeville, Frédéric; Receveur, Marie-Catherine; Pistone, Thierry; Fialon, Pierre; Vincendeau, Philippe; Fleury, Hervé; Malvy, Denis

2008-01-01

Background A simple real-time PCR assay using one set of primer and probe for rapid, sensitive and quantitative detection of Plasmodium species, with simultaneous differentiation of Plasmodium falciparum from the three other Plasmodium species (Plasmodium vivax, Plasmodium ovale and Plasmodium malariae) in febrile returning travellers and migrants was developed and evaluated. Methods Consensus primers were used to amplify a species-specific region of the multicopy 18S rRNA gene, and fluorescence resonance energy transfer hybridization probes were used for detection in a LightCycler platform (Roche). The anchor probe sequence was designed to be perfect matches to the 18S rRNA gene of the fourth Plasmodium species, while the acceptor probe sequence was designed for P. falciparum over a region containing one mismatched, which allowed differentiation of the three other Plasmodium species. The performance characteristics of the real-time PCR assay were compared with those of conventional PCR and microscopy-based diagnosis from 119 individuals with a suspected clinical diagnostic of imported malaria. Results Blood samples with parasite densities less than 0.01% were all detected, and analytical sensitivity was 0.5 parasite per PCR reaction. The melt curve means Tms (standard deviation) in clinical isolates were 60.5°C (0.6°C) for P. falciparum infection and 64.6°C (1.8°C) for non-P. falciparum species. These Tms values of the P. falciparum or non-P. falciparum species did not vary with the geographic origin of the parasite. The real-time PCR results correlated with conventional PCR using both genus-specific (Kappa coefficient: 0.95, 95% confidence interval: 0.9 – 1) or P. falciparum-specific (0.91, 0.8 – 1) primers, or with the microscopy results (0.70, 0.6 – 0.8). The real-time assay was 100% sensitive and specific for differentiation of P. falciparum to non-P. falciparum species, compared with conventional PCR or microscopy. The real-time PCR assay can also detect individuals with mixed infections (P. falciparum and non-P. falciparum sp.) in the same sample. Conclusion This real-time PCR assay with melting curve analysis is rapid, and specific for the detection and differentiation of P. falciparum to other Plasmodium species. The suitability for routine use of this assay in clinical diagnostic laboratories is discussed. PMID:18442362

Ex Vivo Susceptibility of Plasmodium falciparum to Antimalarial Drugs in Western, Northern, and Eastern Cambodia, 2011-2012: Association with Molecular Markers

PubMed Central

Lim, Pharath; Dek, Dalin; Try, Vorleak; Eastman, Richard T.; Chy, Sophy; Sreng, Sokunthea; Suon, Seila; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Ashley, Elizabeth A.; Miotto, Olivo; Dondorp, Arjen M.; White, Nicholas J.; Su, Xin-zhuan; Char, Meng Chuor; Anderson, Jennifer M.; Amaratunga, Chanaki; Menard, Didier

2013-01-01

In 2008, dihydroartemisinin (DHA)-piperaquine (PPQ) became the first-line treatment for uncomplicated Plasmodium falciparum malaria in western Cambodia. Recent reports of increased treatment failure rates after DHA-PPQ therapy in this region suggest that parasite resistance to DHA, PPQ, or both is now adversely affecting treatment. While artemisinin (ART) resistance is established in western Cambodia, there is no evidence of PPQ resistance. To monitor for resistance to PPQ and other antimalarials, we measured drug susceptibilities for parasites collected in 2011 and 2012 from Pursat, Preah Vihear, and Ratanakiri, in western, northern, and eastern Cambodia, respectively. Using a SYBR green I fluorescence assay, we calculated the ex vivo 50% inhibitory concentrations (IC50s) of 310 parasites to six antimalarials: chloroquine (CQ), mefloquine (MQ), quinine (QN), PPQ, artesunate (ATS), and DHA. Geometric mean IC50s (GMIC50s) for all drugs (except PPQ) were significantly higher in Pursat and Preah Vihear than in Ratanakiri (P ≤ 0.001). An increased copy number of P. falciparum mdr1 (pfmdr1), an MQ resistance marker, was more prevalent in Pursat and Preah Vihear than in Ratanakiri and was associated with higher GMIC50s for MQ, QN, ATS, and DHA. An increased copy number of a chromosome 5 region (X5r), a candidate PPQ resistance marker, was detected in Pursat but was not associated with reduced susceptibility to PPQ. The ex vivo IC50 and pfmdr1 copy number are important tools in the surveillance of multidrug-resistant (MDR) parasites in Cambodia. While MDR P. falciparum is prevalent in western and northern Cambodia, there is no evidence for PPQ resistance, suggesting that DHA-PPQ treatment failures result mainly from ART resistance. PMID:23939897

Chloroquine-resistant Plasmodium vivax in transmigration settlements of West Kalimantan, Indonesia.

PubMed

Fryauff, D J; Tuti, S; Mardi, A; Masbar, S; Patipelohi, R; Leksana, B; Kain, K C; Bangs, M J; Richie, T L; Baird, J K

1998-10-01

Malariometric surveys were conducted during July 1996 in native Dayak villages and predominantly Javanese transmigration settlements in Ketapang district of West Kalimantan, Indonesia. Malaria prevalence ranged from 0.9% to 2.7% in Dayak villages and from 1% to 20% in the transmigration settlements. Plasmodium falciparum accounted for 67% of the cases among Dayaks but P. vivax was dominant among transmigrants, accounting for more than 72% of the infections. Chloroquine sensitivity/resistance was assessed by 28-day in vivo testing of uncomplicated malaria infections and measurement of chloroquine blood levels in cases where parasitemias reappeared within the 28-day test period. Resistance was based on the appearance of asexual parasites against chloroquine plus desethylchloroquine levels exceeding the minimally effective whole blood concentrations proposed for sensitive parasite strains (P. vivax, 100 ng/ml; P. falciparum, 200 ng/ml). All parasitemias cleared initially within four days of beginning supervised chloroquine therapy (25 mg base/kg over a 48-hr period), but asexual parasites reappeared within 28 days in 27 of 52 P. vivax and three of 12 P. falciparum cases. Chloroquine blood levels at the time of recurrent parasitemias revealed resistance in 12 of the 27 P. vivax cases and in one of the three P. falciparum cases. Genotypes of nine of the 12 recurrent P. vivax isolates matched with their primary isolates and ruled out reinfection. These findings establish the presence of chloroquine-resistant P. vivax on the island of Borneo. The pattern of malaria and the high frequency of chloroquine resistance by P. vivax at the West Kalimantan location may relate to demographic, ecologic, agricultural, and socioeconomic changes associated with transmigration.

Polymorphisms of the artemisinin resistant marker (K13) in Plasmodium falciparum parasite populations of Grande Comore Island 10 years after artemisinin combination therapy.

PubMed

Huang, Bo; Deng, Changsheng; Yang, Tao; Xue, Linlu; Wang, Qi; Huang, Shiguang; Su, Xin-zhuan; Liu, Yajun; Zheng, Shaoqin; Guan, Yezhi; Xu, Qin; Zhou, Jiuyao; Yuan, Jie; Bacar, Afane; Abdallah, Kamal Said; Attoumane, Rachad; Mliva, Ahamada M S A; Zhong, Yanchun; Lu, Fangli; Song, Jianping

2015-12-15

Plasmodium falciparum malaria is a significant public health problem in Comoros, and artemisinin combination therapy (ACT) remains the first choice for treating acute uncomplicated P. falciparum. The emergence and spread of artemisinin-resistant P. falciparum in Southeast Asia, associated with mutations in K13-propeller gene, poses a potential threat to ACT efficacy. Detection of mutations in the P. falciparum K13-propeller gene may provide the first-hand information on changes in parasite susceptibility to artemisinin. The objective of this study is to determinate the prevalence of mutant K13-propeller gene among the P. falciparum isolates collected from Grande Comore Island, Union of Comoros, where ACT has been in use since 2004. A total of 207 P. falciparum clinical isolates were collected from the island during March 2006 and October 2007 (n = 118) and March 2013 and December 2014 (n = 89). All isolates were analysed for single nucleotide polymorphisms (SNPs) and haplotypes in the K13-propeller gene using nested PCR and DNA sequencing. Only three 2006-2007 samples carried SNPs in the K13-propeller gene, one having a synonymous (G538G) and the other having two non-synonymous (S477Y and D584E) substitutions leading to two mutated haplotypes (2.2%, 2/95). Three synonymous mutations (R471R, Y500Y, and G538G) (5.9%, 5/85) and 7 non-synonymous substitutions (21.2%, 18/85) with nine mutated haplotypes (18.8%, 16/85) were found in isolates from 2013 to 2014. However, none of the polymorphisms associated with artemisinin-resistance in Southeast Asia was detected from any of the parasites examined. This study showed increased K13-propeller gene diversity among P. falciparum populations on the Island over the course of 8 years (2006-2014). Nevertheless, none of the polymorphisms known to be associated with artemisinin resistance in Asia was detected in the parasite populations examined. Our data suggest that P. falciparum populations in Grande Comore are still effectively susceptible to artemisinin. Our results provide insights into P. falciparum populations regarding mutations in the gene associated with artemisinin resistance and will be useful for developing and updating anti-malarial guidance in Comoros.

Mefloquine resistance in Plasmodium falciparum and increased pfmdr1 gene copy number

PubMed Central

Brockman, Alan; McGready, Rose; Ashley, Elizabeth; Phaipun, Lucy; Patel, Rina; Laing, Kenneth; Looareesuwan, Sornchai; White, Nicholas J; Nosten, François; Krishna, Sanjeev

2015-01-01

Summary Background The borders of Thailand harbour the world’s most multidrug resistant Plasmodium falciparum parasites. In 1984 mefloquine was introduced as treatment for uncomplicated falciparum malaria, but substantial resistance developed within 6 years. A combination of artesunate with mefloquine now cures more than 95% of acute infections. For both treatment regimens, the underlying mechanisms of resistance are not known. Methods The relation between polymorphisms in the P falciparum multidrug resistant gene 1 (pfmdr1) and the in-vitro and in-vivo responses to mefloquine were assessed in 618 samples from patients with falciparum malaria studied prospectively over 12 years. pfmdr1 copy number was assessed by a robust real-time PCR assay. Single nucleotide polymorphisms of pfmdr1, P falciparum chloroquine resistance transporter gene (pfcrt) and P falciparum Ca2+ ATPase gene (pfATP6) were assessed by PCR-restriction fragment length polymorphism. Findings Increased copy number of pfmdr1 was the most important determinant of in-vitro and in-vivo resistance to mefloquine, and also to reduced artesunate sensitivity in vitro. In a Cox regression model with control for known confounders, increased pfmdr1 copy number was associated with an attributable hazard ratio (AHR) for treatment failure of 6·3 (95% CI 2·9–13·8, p<0·001) after mefloquine monotherapy and 5·4 (2·0-14·6, p=0·001) after artesunate-mefloquine therapy. Single nucleotide polymorphisms in pfmdr1 were associated with increased mefloquine susceptibility in vitro, but not in vivo. Interpretation Amplification in pfmdr1 is the main cause of resistance to mefloquine in falciparum malaria. Relevance to practice Multidrug resistant P falciparum malaria is common in southeast Asia, but difficult to identify and treat. Genes that encode parasite transport proteins maybe involved in export of drugs and so cause resistance. In this study we show that increase in copy number of pfmdr1, a gene encoding a parasite transport protein, is the best overall predictor of treatment failure with mefloquine. Increase in pfmdr1 copy number predicts failure even after chemotherapy with the highly effective combination of mefloquine and 3 days’ artesunate. Monitoring of pfmdr1 copy number will be useful in epidemiological surveys of drug resistance in P falciparum, and potentially for predicting treatment failure in individual patients. PMID:15288742

Mefloquine resistance in Plasmodium falciparum and increased pfmdr1 gene copy number.

PubMed

Price, Ric N; Uhlemann, Anne-Catrin; Brockman, Alan; McGready, Rose; Ashley, Elizabeth; Phaipun, Lucy; Patel, Rina; Laing, Kenneth; Looareesuwan, Sornchai; White, Nicholas J; Nosten, François; Krishna, Sanjeev

The borders of Thailand harbour the world's most multidrug resistant Plasmodium falciparum parasites. In 1984 mefloquine was introduced as treatment for uncomplicated falciparum malaria, but substantial resistance developed within 6 years. A combination of artesunate with mefloquine now cures more than 95% of acute infections. For both treatment regimens, the underlying mechanisms of resistance are not known. The relation between polymorphisms in the P falciparum multidrug resistant gene 1 (pfmdr1) and the in-vitro and in-vivo responses to mefloquine were assessed in 618 samples from patients with falciparum malaria studied prospectively over 12 years. pfmdr1 copy number was assessed by a robust real-time PCR assay. Single nucleotide polymorphisms of pfmdr1, P falciparum chloroquine resistance transporter gene (pfcrt) and P falciparum Ca2+ ATPase gene (pfATP6) were assessed by PCR-restriction fragment length polymorphism. Increased copy number of pfmdr1 was the most important determinant of in-vitro and in-vivo resistance to mefloquine, and also to reduced artesunate sensitivity in vitro. In a Cox regression model with control for known confounders, increased pfmdr1 copy number was associated with an attributable hazard ratio (AHR) for treatment failure of 6.3 (95% CI 2.9-13.8, p<0.001) after mefloquine monotherapy and 5.4 (2.0-14.6, p=0.001) after artesunate-mefloquine therapy. Single nucleotide polymorphisms in pfmdr1 were associated with increased mefloquine susceptibility in vitro, but not in vivo. Amplification in pfmdr1 is the main cause of resistance to mefloquine in falciparum malaria. Multidrug resistant P falciparum malaria is common in southeast Asia, but difficult to identify and treat. Genes that encode parasite transport proteins maybe involved in export of drugs and so cause resistance. In this study we show that increase in copy number of pfmdr1, a gene encoding a parasite transport protein, is the best overall predictor of treatment failure with mefloquine. Increase in pfmdr1 copy number predicts failure even after chemotherapy with the highly effective combination of mefloquine and 3 days' artesunate. Monitoring of pfmdr1 copy number will be useful in epidemiological surveys of drug resistance in P falciparum, and potentially for predicting treatment failure in individual patients.

Genetic evidence for contribution of human dispersal to the genetic diversity of EBA-175 in Plasmodium falciparum.

PubMed

Yasukochi, Yoshiki; Naka, Izumi; Patarapotikul, Jintana; Hananantachai, Hathairad; Ohashi, Jun

2015-08-01

The 175-kDa erythrocyte binding antigen (EBA-175) of Plasmodium falciparum plays a crucial role in merozoite invasion into human erythrocytes. EBA-175 is believed to have been under diversifying selection; however, there have been no studies investigating the effect of dispersal of humans out of Africa on the genetic variation of EBA-175 in P. falciparum. The PCR-direct sequencing was performed for a part of the eba-175 gene (regions II and III) using DNA samples obtained from Thai patients infected with P. falciparum. The divergence times for the P. falciparum eba-175 alleles were estimated assuming that P. falciparum/Plasmodium reichenowi divergence occurred 6 million years ago (MYA). To examine the possibility of diversifying selection, nonsynonymous and synonymous substitution rates for Plasmodium species were also estimated. A total of 32 eba-175 alleles were identified from 131 Thai P. falciparum isolates. Their estimated divergence time was 0.13-0.14 MYA, before the exodus of humans from Africa. A phylogenetic tree for a large sequence dataset of P. falciparum eba-175 alleles from across the world showed the presence of a basal Asian-specific cluster for all P. falciparum sequences. A markedly more nonsynonymous substitutions than synonymous substitutions in region II in P. falciparum was also detected, but not within Plasmodium species parasitizing African apes, suggesting that diversifying selection has acted specifically on P. falciparum eba-175. Plasmodium falciparum eba-175 genetic diversity appeared to increase following the exodus of Asian ancestors from Africa. Diversifying selection may have played an important role in the diversification of eba-175 allelic lineages. The present results suggest that the dispersals of humans out of Africa influenced significantly the molecular evolution of P. falciparum EBA-175.

Pyronaridine-artesunate granules versus artemether-lumefantrine crushed tablets in children with Plasmodium falciparum malaria: a randomized controlled trial

PubMed Central

2012-01-01

Background Children are most vulnerable to malaria. A pyronaridine-artesunate pediatric granule formulation is being developed for the treatment of uncomplicated Plasmodium falciparum malaria. Methods This phase III, multi-center, comparative, open-label, parallel-group, controlled clinical trial included patients aged ≤12 years, bodyweight ≥5 to <25 kg, with a reported history of fever at inclusion or in the previous 24 h and microscopically-confirmed uncomplicated P. falciparum malaria. Patients were randomized (2:1) to pyronaridine-artesunate granules (60/20 mg) once daily or artemether-lumefantrine crushed tablets (20/120 mg) twice daily, both dosed by bodyweight, orally (liquid suspension) for three days. Results Of 535 patients randomized, 355 received pyronaridine-artesunate and 180 received artemether-lumefantrine. Day-28 adequate clinical and parasitological response (ACPR), corrected for re-infection using polymerase chain reaction (PCR) genotyping (per-protocol population) was 97.1% (329/339; 95% CI 94.6, 98.6) for pyronaridine-artesunate; 98.8% (165/167; 95% CI 95.7, 99.9) for artemether-lumefantrine. The primary endpoint was achieved: pyronaridine-artesunate PCR-corrected day-28 ACPR was statistically significantly >90% (P < .0001). Pyronaridine-artesunate was non-inferior to artemether-lumefantrine: treatment difference -1.8% (95% CI -4.3 to 1.6). The incidence of drug-related adverse events was 37.2% (132/355) with pyronaridine-artesunate, 44.4% (80/180) with artemether-lumefantrine. Clinical biochemistry results showed similar mean changes versus baseline in the two treatment groups. From day 3 until study completion, one patient in each treatment group had peak alanine aminotransferase (ALT) >3 times the upper limit of normal (ULN) and peak total bilirubin >2xULN (i.e. within the Hy’s law definition). Conclusions The pyronaridine-artesunate pediatric granule formulation was efficacious and was non-inferior to artemether-lumefantrine. The adverse event profile was similar for the two comparators. Pyronaridine-artesunate should be considered for inclusion in paediatric malaria treatment programmes. Trial registration ClinicalTrials.gov: identifier NCT00541385 PMID:23113947

Drug Evaluation in the Plasmodium falciparum - Aotus Model

DTIC Science & Technology

1984-09-01

consecutive days to Colombian Aotus. Six amodiaquin analogues were evaluated for their capacity to cure in- fections of chloroquine -sensitive and...AMODIAQUIN ANALOGUES AND AMODIAQUIN AGAINST INFECTIONS OF CHLOROQUINE -SENSITIVE AND CHLOROQUINE -RESISTANT STRAINS OF PLASMODIUM FALCIPARUM 14...AMODIAQUIN ANALOGUES AND AMOOIAQUIN AGAINST INFECTIONS OF CHLOROQUINE -SENSITIVE AND CHLOROQUINE - RESISTANT STRAINS OF PLASMODIUM FALCIPARUM Following

Preliminary Investigation of the Contribution of CYP2A6, CYP2B6, and UGT1A9 Polymorphisms on Artesunate-Mefloquine Treatment Response in Burmese Patients with Plasmodium falciparum Malaria

PubMed Central

Phompradit, Papichaya; Muhamad, Poonuch; Cheoymang, Anurak; Na-Bangchang, Kesara

2014-01-01

CYP2A6, CYP2B6, and UGT1A9 genetic polymorphisms and treatment response after a three-day course of artesunate-mefloquine was investigated in 71 Burmese patients with uncomplicated Plasmodium falciparum malaria. Results provide evidence for the possible link between CYP2A6 and CYP2B6 polymorphisms and plasma concentrations of artesunate/dihydroartemisinin and treatment response. In one patient who had the CYP2A6*1A/*4C genotype (decreased enzyme activity), plasma concentration of artesunate at one hour appeared to be higher, and the concentration of dihydroartemisinin was lower than for those carrying other genotypes (415 versus 320 ng/mL). The proportion of patients with adequate clinical and parasitologic response who had the CYP2B6*9/*9 genotype (mutant genotype) was significantly lower compared with those with late parasitologic failure (14.0% versus 19.0%). Confirmation through a larger study in various malaria-endemic areas is required before a definite conclusion on the role of genetic polymorphisms of these drug-metabolizing enzymes on treatment response after artesunate-based combination therapy can be made. PMID:24891466

Limitations of microscopy to differentiate Plasmodium species in a region co-endemic for Plasmodium falciparum, Plasmodium vivax and Plasmodium knowlesi

PubMed Central

2013-01-01

Background In areas co-endemic for multiple Plasmodium species, correct diagnosis is crucial for appropriate treatment and surveillance. Species misidentification by microscopy has been reported in areas co-endemic for vivax and falciparum malaria, and may be more frequent in regions where Plasmodium knowlesi also commonly occurs. Methods This prospective study in Sabah, Malaysia, evaluated the accuracy of routine district and referral hospital-based microscopy, and microscopy performed by an experienced research microscopist, for the diagnosis of PCR-confirmed Plasmodium falciparum, P. knowlesi, and Plasmodium vivax malaria. Results A total of 304 patients with PCR-confirmed Plasmodium infection were enrolled, including 130 with P. knowlesi, 122 with P. falciparum, 43 with P. vivax, one with Plasmodium malariae and eight with mixed species infections. Among patients with P. knowlesi mono-infection, routine and cross-check microscopy both identified 94 (72%) patients as “P. malariae/P. knowlesi”; 17 (13%) and 28 (22%) respectively were identified as P. falciparum, and 13 (10%) and two (1.5%) as P. vivax. Among patients with PCR-confirmed P. falciparum, routine and cross-check microscopy identified 110/122 (90%) and 112/118 (95%) patients respectively as P. falciparum, and 8/122 (6.6%) and 5/118 (4.2%) as “P. malariae/P. knowlesi”. Among those with P. vivax, 23/43 (53%) and 34/40 (85%) were correctly diagnosed by routine and cross-check microscopy respectively, while 13/43 (30%) and 3/40 (7.5%) patients were diagnosed as “P. malariae/P. knowlesi”. Four of 13 patients with PCR-confirmed P. vivax and misdiagnosed by routine microscopy as “P. malariae/P. knowlesi” were subsequently re-admitted with P. vivax malaria. Conclusions Microscopy does not reliably distinguish between P. falciparum, P. vivax and P. knowlesi in a region where all three species frequently occur. Misdiagnosis of P. knowlesi as both P. vivax and P. falciparum, and vice versa, is common, potentially leading to inappropriate treatment, including chloroquine therapy for P. falciparum and a lack of anti-relapse therapy for P. vivax. The limitations of microscopy in P. knowlesi-endemic areas supports the use of unified blood-stage treatment strategies for all Plasmodium species, the development of accurate rapid diagnostic tests suitable for all species, and the use of PCR-confirmation for accurate surveillance. PMID:23294844

Rapid diagnostic tests for diagnosing uncomplicated non-falciparum or Plasmodium vivax malaria in endemic countries

PubMed Central

Abba, Katharine; Kirkham, Amanda J; Olliaro, Piero L; Deeks, Jonathan J; Donegan, Sarah; Garner, Paul; Takwoingi, Yemisi

2014-01-01

Background In settings where both Plasmodium vivax and Plasmodium falciparum infection cause malaria, rapid diagnostic tests (RDTs) need to distinguish which species is causing the patients' symptoms, as different treatments are required. Older RDTs incorporated two test lines to distinguish malaria due to P. falciparum, from malaria due to any other Plasmodium species (non-falciparum). These RDTs can be classified according to which antibodies they use: Type 2 RDTs use HRP-2 (for P. falciparum) and aldolase (all species); Type 3 RDTs use HRP-2 (for P. falciparum) and pLDH (all species); Type 4 use pLDH (fromP. falciparum) and pLDH (all species). More recently, RDTs have been developed to distinguish P. vivax parasitaemia by utilizing a pLDH antibody specific to P. vivax. Objectives To assess the diagnostic accuracy of RDTs for detecting non-falciparum or P. vivax parasitaemia in people living in malaria-endemic areas who present to ambulatory healthcare facilities with symptoms suggestive of malaria, and to identify which types and brands of commercial test best detect non-falciparum and P. vivax malaria. Search methods We undertook a comprehensive search of the following databases up to 31 December 2013: Cochrane Infectious Diseases Group Specialized Register; MEDLINE; EMBASE; MEDION; Science Citation Index; Web of Knowledge; African Index Medicus; LILACS; and IndMED. Selection criteria Studies comparing RDTs with a reference standard (microscopy or polymerase chain reaction) in blood samples from a random or consecutive series of patients attending ambulatory health facilities with symptoms suggestive of malaria in non-falciparum endemic areas. Data collection and analysis For each study, two review authors independently extracted a standard set of data using a tailored data extraction form. We grouped comparisons by type of RDT (defined by the combinations of antibodies used), and combined in meta-analysis where appropriate. Average sensitivities and specificities are presented alongside 95% confidence intervals (95% CI). Main results We included 47 studies enrolling 22,862 participants. Patient characteristics, sampling methods and reference standard methods were poorly reported in most studies. RDTs detecting 'non-falciparum' parasitaemia Eleven studies evaluated Type 2 tests compared with microscopy, 25 evaluated Type 3 tests, and 11 evaluated Type 4 tests. In meta-analyses, average sensitivities and specificities were 78% (95% CI 73% to 82%) and 99% (95% CI 97% to 99%) for Type 2 tests, 78% (95% CI 69% to 84%) and 99% (95% CI 98% to 99%) for Type 3 tests, and 89% (95% CI 79% to 95%) and 98% (95% CI 97% to 99%) for Type 4 tests, respectively. Type 4 tests were more sensitive than both Type 2 (P = 0.01) and Type 3 tests (P = 0.03). Five studies compared Type 3 tests with PCR; in meta-analysis, the average sensitivity and specificity were 81% (95% CI 72% to 88%) and 99% (95% CI 97% to 99%) respectively. RDTs detecting P.vivax parasitaemia Eight studies compared pLDH tests to microscopy; the average sensitivity and specificity were 95% (95% CI 86% to 99%) and 99% (95% CI 99% to 100%), respectively. Authors' conclusions RDTs designed to detect P. vivax specifically, whether alone or as part of a mixed infection, appear to be more accurate than older tests designed to distinguish P. falciparum malaria from non-falciparum malaria. Compared to microscopy, these tests fail to detect around 5% ofP. vivax cases. This Cochrane Review, in combination with other published information about in vitro test performance and stability in the field, can assist policy-makers to choose between the available RDTs. PLAIN LANGUAGE SUMMARY Rapid tests for diagnosing malaria caused by Plasmodium vivax or other less common parasites This review summarises trials evaluating the accuracy of rapid diagnostic tests (RDTs) for diagnosing malaria due to Plasmodium vivax or other non-falciparum species. After searching for relevant studies up to December 2013, we included 47 studies, enrolling 22,862 adults and children. What are rapid tests and why do they need to be able to distinguish Plasmodium vivax malaria RDTs are simple to use, point of care tests, suitable for use in rural settings by primary healthcare workers. RDTs work by using antibodies to detect malaria antigens in the patient's blood. A drop of blood is placed on the test strip where the antibodies and antigen combine to create a distinct line indicating a positive test. Malaria can be caused any one of five species of Plasmodium parasite, but P. falciparum and P. vivax are the most common. In some areas, RDTs need to be able to distinguish which species is causing the malaria symptoms as different species may require different treatments. Unlike P. falciparum, P. vivax has a liver stage which can cause repeated illness every few months unless it is treated with primaquine. The most common types of RDTs for P. vivax use two test lines in combination; one line specific to P. falciparum, and one line which can detect any species of Plasmodium. If the P. falciparum line is negative and the 'any species' line is positive, the illness is presumed to be due to P. vivax (but could also be caused by P. malariae, or P. ovale). More recently, RDTs have been developed which specifically test for P. vivax. What does the research say RDTs testing for non-falciparum malaria were very specific (range 98% to 100%) meaning that only 1% to 2% of patients who test positive would actually not have the disease. However, they were less sensitive (range 78% to 89%), meaning between 11% and 22% of people with non-falciparum malaria would actually get a negative test result. RDTs which specifically tested for P. vivax were more accurate with a specificity of 99% and a sensitivity of 95%, meaning that only 5% of people with P. vivax malaria would have a negative test result. PMID:25519857

Selection of Plasmodium falciparum pfcrt and pfmdr1 polymorphisms after treatment with artesunate-amodiaquine fixed dose combination or artemether-lumefantrine in Liberia.

PubMed

Otienoburu, Sabina Dahlström; Maïga-Ascofaré, Oumou; Schramm, Birgit; Jullien, Vincent; Jones, Joel J; Zolia, Yah M; Houzé, Pascal; Ashley, Elizabeth A; Kiechel, Jean-René; Guérin, Philippe J; Le Bras, Jacques; Houzé, Sandrine

2016-09-05

Plasmodium falciparum uncomplicated malaria can successfully be treated with an artemisinin-based combination therapy (ACT). However resistance is spreading to the different ACT compounds; the artemisinin derivative and the partner drug. Studies of P. falciparum polymorphisms associated with drug resistance can provide a useful tool to track resistance and guide treatment policy as well as an in-depth understanding of the development and spread of resistance. The role of P. falciparum molecular markers in selection of reinfections was assessed in an efficacy trial comparing artesunate-amodiaquine fixed-dose combination with artemether-lumefantrine to treat malaria in Nimba County, Liberia 2008-2009. P. falciparum polymorphisms in pfcrt 76, pfmdr1 86, 184 and 1246, and pfmrp1 876 and 1466 were analysed by PCR-RFLP and pyrosequencing. High baseline prevalence of pfmdr1 1246Y was found in Nimba county (38 %). Pfmdr1 1246Y and pfmdr1 86+184+1246 haplotypes NYY and YYY were selected in reinfections in the artesunate-amodiaquine arm and pfcrt K76, pfmdr1 N86 and pfmdr1 haplotype NFD were selected in artemether-lumefantrine reinfections. Parasites harbouring pfmdr1 1246Y could reinfect earlier after treatment with artesunate-amodiaquine and parasites carrying pfmdr1 N86 could reinfect at higher lumefantrine concentrations in patients treated with artemether-lumefantrine. Although treatment is highly efficacious, selection of molecular markers in reinfections could indicate a decreased sensitivity or tolerance of parasites to the current treatments and the baseline prevalence of molecular markers should be closely monitored. Since individual drug levels and the day of reinfection were demonstrated to be key determinants for selection of reinfections, this data needs to be collected and taken into account for accurate evaluation of molecular markers for anti-malarial treatments. The protocols for the clinical trial was registered with Current Controlled Trials, under the Identifier Number ISRCTN51688713 on 9 October 2008.

Spread of artemisinin resistance in Plasmodium falciparum malaria.

PubMed

Ashley, Elizabeth A; Dhorda, Mehul; Fairhurst, Rick M; Amaratunga, Chanaki; Lim, Parath; Suon, Seila; Sreng, Sokunthea; Anderson, Jennifer M; Mao, Sivanna; Sam, Baramey; Sopha, Chantha; Chuor, Char Meng; Nguon, Chea; Sovannaroth, Siv; Pukrittayakamee, Sasithon; Jittamala, Podjanee; Chotivanich, Kesinee; Chutasmit, Kitipumi; Suchatsoonthorn, Chaiyaporn; Runcharoen, Ratchadaporn; Hien, Tran Tinh; Thuy-Nhien, Nguyen Thanh; Thanh, Ngo Viet; Phu, Nguyen Hoan; Htut, Ye; Han, Kay-Thwe; Aye, Kyin Hla; Mokuolu, Olugbenga A; Olaosebikan, Rasaq R; Folaranmi, Olaleke O; Mayxay, Mayfong; Khanthavong, Maniphone; Hongvanthong, Bouasy; Newton, Paul N; Onyamboko, Marie A; Fanello, Caterina I; Tshefu, Antoinette K; Mishra, Neelima; Valecha, Neena; Phyo, Aung Pyae; Nosten, Francois; Yi, Poravuth; Tripura, Rupam; Borrmann, Steffen; Bashraheil, Mahfudh; Peshu, Judy; Faiz, M Abul; Ghose, Aniruddha; Hossain, M Amir; Samad, Rasheda; Rahman, M Ridwanur; Hasan, M Mahtabuddin; Islam, Akhterul; Miotto, Olivo; Amato, Roberto; MacInnis, Bronwyn; Stalker, Jim; Kwiatkowski, Dominic P; Bozdech, Zbynek; Jeeyapant, Atthanee; Cheah, Phaik Yeong; Sakulthaew, Tharisara; Chalk, Jeremy; Intharabut, Benjamas; Silamut, Kamolrat; Lee, Sue J; Vihokhern, Benchawan; Kunasol, Chanon; Imwong, Mallika; Tarning, Joel; Taylor, Walter J; Yeung, Shunmay; Woodrow, Charles J; Flegg, Jennifer A; Das, Debashish; Smith, Jeffery; Venkatesan, Meera; Plowe, Christopher V; Stepniewska, Kasia; Guerin, Philippe J; Dondorp, Arjen M; Day, Nicholas P; White, Nicholas J

2014-07-31

Artemisinin resistance in Plasmodium falciparum has emerged in Southeast Asia and now poses a threat to the control and elimination of malaria. Mapping the geographic extent of resistance is essential for planning containment and elimination strategies. Between May 2011 and April 2013, we enrolled 1241 adults and children with acute, uncomplicated falciparum malaria in an open-label trial at 15 sites in 10 countries (7 in Asia and 3 in Africa). Patients received artesunate, administered orally at a daily dose of either 2 mg per kilogram of body weight per day or 4 mg per kilogram, for 3 days, followed by a standard 3-day course of artemisinin-based combination therapy. Parasite counts in peripheral-blood samples were measured every 6 hours, and the parasite clearance half-lives were determined. The median parasite clearance half-lives ranged from 1.9 hours in the Democratic Republic of Congo to 7.0 hours at the Thailand-Cambodia border. Slowly clearing infections (parasite clearance half-life >5 hours), strongly associated with single point mutations in the "propeller" region of the P. falciparum kelch protein gene on chromosome 13 (kelch13), were detected throughout mainland Southeast Asia from southern Vietnam to central Myanmar. The incidence of pretreatment and post-treatment gametocytemia was higher among patients with slow parasite clearance, suggesting greater potential for transmission. In western Cambodia, where artemisinin-based combination therapies are failing, the 6-day course of antimalarial therapy was associated with a cure rate of 97.7% (95% confidence interval, 90.9 to 99.4) at 42 days. Artemisinin resistance to P. falciparum, which is now prevalent across mainland Southeast Asia, is associated with mutations in kelch13. Prolonged courses of artemisinin-based combination therapies are currently efficacious in areas where standard 3-day treatments are failing. (Funded by the U.K. Department of International Development and others; ClinicalTrials.gov number, NCT01350856.).

Erythrocytic adenosine monophosphate as an alternative purine source in Plasmodium falciparum.

PubMed

Cassera, María B; Hazleton, Keith Z; Riegelhaupt, Paul M; Merino, Emilio F; Luo, Minkui; Akabas, Myles H; Schramm, Vern L

2008-11-21

Plasmodium falciparum is a purine auxotroph, salvaging purines from erythrocytes for synthesis of RNA and DNA. Hypoxanthine is the key precursor for purine metabolism in Plasmodium. Inhibition of hypoxanthine-forming reactions in both erythrocytes and parasites is lethal to cultured P. falciparum. We observed that high concentrations of adenosine can rescue cultured parasites from purine nucleoside phosphorylase and adenosine deaminase blockade but not when erythrocyte adenosine kinase is also inhibited. P. falciparum lacks adenosine kinase but can salvage AMP synthesized in the erythrocyte cytoplasm to provide purines when both human and Plasmodium purine nucleoside phosphorylases and adenosine deaminases are inhibited. Transport studies in Xenopus laevis oocytes expressing the P. falciparum nucleoside transporter PfNT1 established that this transporter does not transport AMP. These metabolic patterns establish the existence of a novel nucleoside monophosphate transport pathway in P. falciparum.

Therapeutic assessment of chloroquine-primaquine combined regimen in adult cohort of Plasmodium vivax malaria from a tertiary care hospital in southwestern India.

PubMed

Rishikesh, Kumar; Kamath, Asha; Hande, Manjunatha H; Vidyasagar, Sudha; Acharya, Raviraja V; Acharya, Vasudeva; Belle, Jayaprakash; Shastry, Ananthakrishna B; Saravu, Kavitha

2015-08-11

Of late there have been accounts of therapeutic failure and chloroquine resistance in Plasmodium vivax malaria especially from Southeast Asian regions. The present study was conducted to assess the therapeutic efficacy of chloroquine-primaquine (CQ-PQ) combined regimen in a cohort of uncomplicated P. vivax mono-infection. A tertiary care hospital-based prospective study was conducted among adult cohort with mono-infection P. vivax malaria as per the World Health Organization's protocol of in vivo assessment of anti-malarial therapeutic efficacy. Participants were treated with CQ 25 mg/kg body weight divided over 3 days and PQ 0.25 mg/kg body weight daily for 2 weeks. Of a total of 125 participants recruited, 122 (97.6%) completed day 28 follow up, three (2.4%) participants were lost to follow-up. Eight patients (6.4%) were ascertained to have mixed P. vivax and Plasmodium falciparum infection by nested polymerase chain reaction test. The majority of subjects (56.8%, 71/125) became aparasitaemic on day 2 followed by 35.2% (44/125) on day 3, and 8% (10/125) on day 7, and remained so thereafter. Overall only one therapeutic failure (0.8%, 1/125) occurred on day 3 due to persistence of fever and parasitaemia. CQ-PQ combined regimen remains outstandingly effective for uncomplicated P. vivax malaria and should be retained as treatment of choice in the study region. One case of treatment failure indicates possible resistance which warrants constant vigilance and periodic surveillance.

Plasmodium falciparum-like parasites infecting wild apes in southern Cameroon do not represent a recurrent source of human malaria

PubMed Central

Sundararaman, Sesh A.; Liu, Weimin; Keele, Brandon F.; Learn, Gerald H.; Bittinger, Kyle; Mouacha, Fatima; Ahuka-Mundeke, Steve; Manske, Magnus; Sherrill-Mix, Scott; Li, Yingying; Malenke, Jordan A.; Delaporte, Eric; Laurent, Christian; Mpoudi Ngole, Eitel; Kwiatkowski, Dominic P.; Shaw, George M.; Rayner, Julian C.; Peeters, Martine; Sharp, Paul M.; Bushman, Frederic D.; Hahn, Beatrice H.

2013-01-01

Wild-living chimpanzees and gorillas harbor a multitude of Plasmodium species, including six of the subgenus Laverania, one of which served as the progenitor of Plasmodium falciparum. Despite the magnitude of this reservoir, it is unknown whether apes represent a source of human infections. Here, we used Plasmodium species-specific PCR, single-genome amplification, and 454 sequencing to screen humans from remote areas of southern Cameroon for ape Laverania infections. Among 1,402 blood samples, we found 1,000 to be Plasmodium mitochondrial DNA (mtDNA) positive, all of which contained human parasites as determined by sequencing and/or restriction enzyme digestion. To exclude low-abundance infections, we subjected 514 of these samples to 454 sequencing, targeting a region of the mtDNA genome that distinguishes ape from human Laverania species. Using algorithms specifically developed to differentiate rare Plasmodium variants from 454-sequencing error, we identified single and mixed-species infections with P. falciparum, Plasmodium malariae, and/or Plasmodium ovale. However, none of the human samples contained ape Laverania parasites, including the gorilla precursor of P. falciparum. To characterize further the diversity of P. falciparum in Cameroon, we used single-genome amplification to amplify 3.4-kb mtDNA fragments from 229 infected humans. Phylogenetic analysis identified 62 new variants, all of which clustered with extant P. falciparum, providing further evidence that P. falciparum emerged following a single gorilla-to-human transmission. Thus, unlike Plasmodium knowlesi-infected macaques in southeast Asia, African apes harboring Laverania parasites do not seem to serve as a recurrent source of human malaria, a finding of import to ongoing control and eradication measures. PMID:23569255

DNA Cloning of Plasmodium falciparum Circumsporozoite Gene: Amino Acid Sequence of Repetitive Epitope

NASA Astrophysics Data System (ADS)

Enea, Vincenzo; Ellis, Joan; Zavala, Fidel; Arnot, David E.; Asavanich, Achara; Masuda, Aoi; Quakyi, Isabella; Nussenzweig, Ruth S.

1984-08-01

A clone of complementary DNA encoding the circumsporozoite (CS) protein of the human malaria parasite Plasmodium falciparum has been isolated by screening an Escherichia coli complementary DNA library with a monoclonal antibody to the CS protein. The DNA sequence of the complementary DNA insert encodes a four-amino acid sequence: proline-asparagine-alanine-asparagine, tandemly repeated 23 times. The CS β -lactamase fusion protein specifically binds monoclonal antibodies to the CS protein and inhibits the binding of these antibodies to native Plasmodium falciparum CS protein. These findings provide a basis for the development of a vaccine against Plasmodium falciparum malaria.

Erythrocytic Adenosine Monophosphate as an Alternative Purine Source in Plasmodium falciparum*

PubMed Central

Cassera, María B.; Hazleton, Keith Z.; Riegelhaupt, Paul M.; Merino, Emilio F.; Luo, Minkui; Akabas, Myles H.; Schramm, Vern L.

2008-01-01

Plasmodium falciparum is a purine auxotroph, salvaging purines from erythrocytes for synthesis of RNA and DNA. Hypoxanthine is the key precursor for purine metabolism in Plasmodium. Inhibition of hypoxanthine-forming reactions in both erythrocytes and parasites is lethal to cultured P. falciparum. We observed that high concentrations of adenosine can rescue cultured parasites from purine nucleoside phosphorylase and adenosine deaminase blockade but not when erythrocyte adenosine kinase is also inhibited. P. falciparum lacks adenosine kinase but can salvage AMP synthesized in the erythrocyte cytoplasm to provide purines when both human and Plasmodium purine nucleoside phosphorylases and adenosine deaminases are inhibited. Transport studies in Xenopus laevis oocytes expressing the P. falciparum nucleoside transporter PfNT1 established that this transporter does not transport AMP. These metabolic patterns establish the existence of a novel nucleoside monophosphate transport pathway in P. falciparum. PMID:18799466

Prolonged Neutrophil Dysfunction Following Plasmodium falciparum Malaria is Related to Hemolysis and Heme Oxygenase-1 Induction1

PubMed Central

Cunnington, Aubrey J.; Njie, Madi; Correa, Simon; Takem, Ebako N.; Riley, Eleanor M.; Walther, Michael

2012-01-01

It is not known why people are more susceptible to bacterial infections such as non-Typhoid Salmonella (NTS) during and after a malaria infection but, in mice, malarial hemolysis impairs resistance to NTS by impairing the neutrophil oxidative burst. This acquired neutrophil dysfunction is a consequence of induction of the cytoprotective, heme degrading enzyme heme oxygenase-1 (HO-1) in neutrophil progenitors in bone marrow. In this study, we assessed whether neutrophil dysfunction occurs in humans with malaria and how this relates to hemolysis. We evaluated neutrophil function in 58 Gambian children with Plasmodium falciparum malaria (55 (95%) with uncomplicated disease), and examined associations with erythrocyte count, haptoglobin, hemopexin, plasma heme, expression of receptors for heme uptake, and HO-1 induction. Malaria caused the appearance of a dominant population of neutrophils with reduced oxidative burst activity, which gradually normalized over 8 weeks of follow-up. The degree of neutrophil impairment correlated significantly with markers of hemolysis and HO-1 induction. HO-1 expression was increased in blood during acute malaria, but at a cellular level HO-1 expression was modulated by changes in surface expression of the haptoglobin receptor (CD163). These findings demonstrate that neutrophil dysfunction occurs in P. falciparum malaria and support the relevance of the mechanistic studies in mice. Furthermore, they suggest the presence of a regulatory pathway to limit HO-1 induction by hemolysis in the context of infection, and indicate new targets for therapeutic intervention to abrogate the susceptibility to bacterial infection in the context of hemolysis in humans. PMID:23100518

Evaluation of a PfHRP2 and a pLDH-based Rapid Diagnostic Test for the Diagnosis of Severe Malaria in 2 Populations of African Children

PubMed Central

Hendriksen, Ilse C. E.; Mtove, George; Pedro, Alínia José; Gomes, Ermelinda; Silamut, Kamolrat; Lee, Sue J.; Mwambuli, Abraham; Gesase, Samwel; Reyburn, Hugh; Day, Nicholas P. J.; White, Nicholas J.; von Seidlein, Lorenz

2011-01-01

Background. Rapid diagnostic tests (RDTs) now play an important role in the diagnosis of falciparum malaria in many countries where the disease is endemic. Although these tests have been extensively evaluated in uncomplicated falciparum malaria, reliable data on their performance for diagnosing potentially lethal severe malaria is lacking. Methods. We compared a Plasmodium falciparum histidine-rich-protein2 (PfHRP2)–based RDT and a Plasmodium lactate dehydrogenase (pLDH)–based RDT with routine microscopy of a peripheral blood slide and expert microscopy as a reference standard for the diagnosis of severe malaria in 1898 children who presented with severe febrile illness at 2 centers in Mozambique and Tanzania. Results. The overall sensitivity, specificity, positive predictive value, and negative predictive values of the PfHRP2-based test were 94.0%, 70.9%, 85.4%, and 86.8%, respectively, and for the pLDH-based test, the values were 88.0%, 88.3%, 93.2%, and 80.3%, respectively. At parasite counts <1000 parasites/μL (n = 173), sensitivity of the pLDH-based test was low (45.7%), compared with that of the PfHRP2-based test (69.9%). Both RDTs performed better than did the routine slide reading in a clinical laboratory as assessed in 1 of the centers. Conclusion. The evaluated PfHRP2-based RDT is an acceptable alternative to routine microscopy for diagnosing severe malaria in African children and performed better than did the evaluated pLDH-based RDT. PMID:21467015

Prevalence of mutations associated with antimalarial drugs in Plasmodium falciparum isolates prior to the introduction of sulphadoxine-pyrimethamine as first-line treatment in Iran

PubMed Central

Zakeri, Sedigheh; Afsharpad, Mandana; Raeisi, Ahmad; Djadid, Navid Dinparast

2007-01-01

Background This work was carried out to assess the patterns and prevalence of resistance to chloroquine (CQ) and sulphadoxine-pyrimethamine (SP) in Iran. Methods The prevalence of pfcrt K76T, pfmdr1 N86Y, pfdhfr N51I, C59R, S108N/T and I164L and codons S436F/A, A437G, K540E, A581E, and A613S/T in pfdhps genes were genotyped by PCR/RFLP methods in 206 Plasmodium falciparum isolates from Chabahar and Sarbaz districts in Sistan and Baluchistan province, Iran, during 2003–2005. Results All P. falciparum isolates carried the 108N, while 98.5% parasite isolates carried the 59R mutation. 98.5% of patients carried both 108N and 59R. The prevalence of pfdhps 437G mutation was 17% (Chabahar) and 33% (Sarbaz) isolates. 20.4% of samples presented the pfdhfr 108N, 59R with pfdhps 437G mutations. The frequency of allele pfcrt 76T was 98%, while 41.4% (Chabahar) and 27.7% (Sarbaz) isolates carried pfmdr1 86Y allele. Eight distinct haplotypes were identified in all 206 samples, while the most prevalent haplotype was T76/N86/N51R59N108/A437 among both study areas. Conclusion Finding the fixed level of CQ resistance polymorphisms (pfcrt 76T) suggests that CQ must be withdrawn from the current treatment strategy in Iran, while SP may remain the treatment of choice for uncomplicated malaria. PMID:17999755

Artemisinin-based combination therapy in the treatment of uncomplicated malaria: review of recent regulatory experience at the European Medicines Agency

PubMed Central

Pelfrene, Eric; Pinheiro, Marie-Hélène; Cavaleri, Marco

2015-01-01

Malaria remains a major public health challenge with almost half of the world's population exposed to the risk of contracting the illness. Prompt, effective and well tolerated treatment remains one of the cornerstones in the disease management, with artemisinin-based combination therapy the recommended option for non-severe malaria in endemic areas with predominant Plasmodium falciparum infections. Recent experience has been obtained at the European Medicines Agency with regulatory approval of two such antimalarial fixed combination products. For these cases, two different regulatory pathways were applied. As such, the present contribution describes this experience, emphasising main differences and applicability offered by these regulatory choices. PMID:25855638

Prolonged Plasmodium falciparum Infection in Immigrants, Paris

PubMed Central

Godineau, Nadine; Fontanet, Arnaud; Houze, Sandrine; Bouchaud, Olivier; Matheron, Sophie; Le Bras, Jacques

2008-01-01

Few immigrant travelers have Plasmodium falciparum infections >2 months after leaving malaria-endemic areas. We conducted a case–control study to identify factors associated with prolonged P. falciparum infection in immigrant travelers. Results suggest that P. falciparum infection should be systematically suspected, even months after travel, especially in pregnant women and first-arrival immigrants. PMID:18258132

Prevalence and distribution of human Plasmodium infection in Pakistan.

PubMed

Khattak, Aamer A; Venkatesan, Meera; Nadeem, Muhammad F; Satti, Humayoon S; Yaqoob, Adnan; Strauss, Kathy; Khatoon, Lubna; Malik, Salman A; Plowe, Christopher V

2013-08-28

Both Plasmodium vivax and Plasmodium falciparum are prevalent in Pakistan, yet up-to-date data on the epidemiology of malaria in Pakistan are not available. This study was undertaken to determine the current prevalence and distribution of Plasmodium species across the country. A malariometric population survey was conducted in 2011 using blood samples collected from 801 febrile patients of all ages in four provinces and the capital city of Islamabad. Microscopically confirmed Plasmodium-positive blood samples were reconfirmed by polymerase chain reaction (PCR). Confirmed parasite-positive samples were subjected to species-specific PCR capable of detecting four species of human malaria. Of the 707 PCR-positive samples, 128 (18%) were P. falciparum, 536 (76%) were P. vivax, and 43 (6%) were mixed P. falciparum and P. vivax. Ninety-four microscopy-positive samples were PCR-negative, and Plasmodium malariae and Plasmodium ovale were not detected. Prevalence of P. vivax ranged from 2.4% in Punjab Province to 10.8% in Sindh Province and prevalence of P. falciparum ranged from 0.1% in Islamabad to 3.8% in Balochistan. Plasmodium infections in Pakistan are largely attributed to P. vivax but P. falciparum and mixed species infections are also prevalent. In addition, regional variation in the prevalence and species composition of malaria is high.

Prevalence and distribution of human Plasmodium infection in Pakistan

PubMed Central

2013-01-01

Background Both Plasmodium vivax and Plasmodium falciparum are prevalent in Pakistan, yet up-to-date data on the epidemiology of malaria in Pakistan are not available. This study was undertaken to determine the current prevalence and distribution of Plasmodium species across the country. Methods A malariometric population survey was conducted in 2011 using blood samples collected from 801 febrile patients of all ages in four provinces and the capital city of Islamabad. Microscopically confirmed Plasmodium-positive blood samples were reconfirmed by polymerase chain reaction (PCR). Confirmed parasite-positive samples were subjected to species-specific PCR capable of detecting four species of human malaria. Results Of the 707 PCR-positive samples, 128 (18%) were P. falciparum, 536 (76%) were P. vivax, and 43 (6%) were mixed P. falciparum and P. vivax. Ninety-four microscopy-positive samples were PCR-negative, and Plasmodium malariae and Plasmodium ovale were not detected. Prevalence of P. vivax ranged from 2.4% in Punjab Province to 10.8% in Sindh Province and prevalence of P. falciparum ranged from 0.1% in Islamabad to 3.8% in Balochistan. Conclusions Plasmodium infections in Pakistan are largely attributed to P. vivax but P. falciparum and mixed species infections are also prevalent. In addition, regional variation in the prevalence and species composition of malaria is high. PMID:23984968

Simple Molecular Methods for Early Detection of Chloroquine Drug Resistance in Plasmodium vivax and Plasmodium falciparum

PubMed Central

Singh, Raksha; Urhehar, Anant Dattatraya

2016-01-01

Introduction Malaria is a human disease of which causes high morbidity and mortality. In Plasmodium falciparum malaria, the resistance to antimalarial drugs, especially chloroquine (CQ) is one of the paramount factors contributing to the global increase in morbidity and mortality, due to malaria. Hence, there is a need for detection of chloroquine drug resistance genes i.e., pfcrt-o (Plasmodium falciparum chloroquine resistance transporter-o) and pfmdr-1 (Plasmodium falciparum multidrug resistance-1) of P. falciparum and pvcrt-o (Plasmodium vivax chloroquine resistance transporter-o) and pvmdr-1 (Plasmodium vivax multidrug resistance-1) of P. vivax by using molecular methods to prevent mortality in malarial cases. Aim To standardize chloroquine drug sensitivity testing by molecular method so as to provide reports of chloroquine within 6-8 hours to physicians for better treatment. Materials and Methods This study was conducted over a period of one year from January to December 2014. A Total of 300 blood samples were collected from malaria suspected patient attending MGM Hospital, Kamothe, Navi Mumbai, India. Out of 300 blood samples, 44 were malaria positive as assessed by Thick and Thin blood smear stained, by Leishman’s method and examination with light microscope. Chloroquine drug sensitivity testing was performed using WHO III plate method (micro test). Nested PCR was done for detection of pfcrt-o and pfmdr-1 for P. falciparum and pvcrt-o, pvmdr-1 genes for P. vivax. Results Total 44 samples were included in this study, out of which 22 samples confirmed for Plasmodium falciparum and 22 samples confirmed for Plasmodium vivax. Out of 22 P. falciparum 15 (68.18%) samples were chloroquine resistant. P. vivax showed chloroquine resistance to 5 samples (22.73%) by method similar to WHO III plate method (micro test) and nested PCR. Conclusion Drug resistance testing by molecular methods is useful for early detection of antimalarial drug resistance. pfmdr-1 along with pfcrt-o can be used as biomarker for chloroquine drug resistance in P. falciparum and pvmdr-1 along with pvcrt-o for P. vivax. PMID:27630842

Biological and Phytochemical Investigations on Caesalpinia benthamiana, a Plant Traditionally Used as Antimalarial in Guinea

PubMed Central

Loua, Jean; Traore, Mohamed Sahar; Camara, Aissata; Balde, Mamadou Aliou; Maes, Louis; Pieters, Luc

2017-01-01

Caesalpinia benthamiana is widely used as antimalarial in Guinean traditional medicine. Leaf extracts of the plant were tested for their in vitro antiprotozoal activity against Trypanosoma brucei brucei and T. cruzi and the chloroquine-sensitive Ghana strain of Plasmodium falciparum along with their cytotoxicity on MRC-5 cells. The methanolic extract showed the strongest antiprotozoal activity against P. falciparum (IC50 4 μg/ml), a good activity against T. brucei (IC50 13 μg/ml), and a moderate activity against T. cruzi (IC50 31 μg/ml) along with an IC50 on human MRC-5 cells of 32 μg/ml. Bioassay-guided fractionation from the methanolic extract led to antiplasmodially active subfractions. A prospective, placebo-controlled ethnotherapeutic trial assessed the antimalarial effectiveness and tolerability of C. benthamiana syrup administered orally to children with uncomplicated malaria as compared with chloroquine syrup. Phytochemical screening of the leaf extracts indicated the presence of flavonoids, terpenoids, tannins, saponins, and iridoids. PMID:29081823

Patterns of Plasmodium vivax and Plasmodium falciparum malaria underscore importance of data collection from private health care facilities in India.

PubMed

Gupta, Sangeeta; Gunter, James T; Novak, Robert J; Regens, James L

2009-10-12

This study describes patterns of falciparum and vivax malaria in a private comprehensive-care, multi-specialty hospital in New Delhi from July 2006 to July 2008. Malarial morbidity by Plasmodium species (Plasmodium falciparum, Plasmodium vivax, or Plasmodium sp.) was confirmed using microscopy and antigen tests. The influence of seasonal factors and selected patient demographics on morbidity was evaluated. The proportions of malaria cases caused by P. falciparum at the private facility were compared to data from India's National Vector Borne Disease Control Programme (NVBDCP) during the same period for the Delhi region. In New Delhi, P. faciparum was the dominant cause of cases requiring treatment in the private hospital during the period examined. The national data reported a smaller proportion of malaria cases caused by P. falciparum in the national capital region than was observed in a private facility within the region. Plasmodium vivax also caused a large proportion of the cases presenting clinically at the private hospital during the summer and monsoon seasons. The proportion of P. falciparum malaria cases tends to be greatest during the post-monsoon season while the proportion of P. vivax malaria cases tends to be greatest in the monsoon season. Private hospital data demonstrate an under-reporting of malaria case incidences in the data from India's national surveillance programme during the same period for the national capital region.

Submicroscopic placental infection by non-falciparum Plasmodium spp.

PubMed

Doritchamou, Justin Y A; Akuffo, Richard A; Moussiliou, Azizath; Luty, Adrian J F; Massougbodji, Achille; Deloron, Philippe; Tuikue Ndam, Nicaise G

2018-02-01

Among the Plasmodium species that infect humans, adverse effects of P. falciparum and P. vivax have been extensively studied and reported with respect to poor outcomes particularly in first time mothers and in pregnant women living in areas with unstable malaria transmission. Although, other non-falciparum malaria infections during pregnancy have sometimes been reported, little is known about the dynamics of these infections during pregnancy. Using a quantitative PCR approach, blood samples collected from Beninese pregnant women during the first antenatal visit (ANV) and at delivery including placental blood were screened for Plasmodium spp. Risk factors associated with Plasmodium spp. infection during pregnancy were assessed as well as the relationships with pregnancy outcomes. P. falciparum was the most prevalent Plasmodium species detected during pregnancy, irrespective either of parity, of age or of season during which the infection occurred. Although no P. vivax infections were detected in this cohort, P. malariae (9.2%) and P. ovale (5.8%) infections were observed in samples collected during the first ANV. These non-falciparum infections were also detected in maternal peripheral blood (1.3% for P. malariae and 1.2% for P. ovale) at delivery. Importantly, higher prevalence of P. malariae (5.5%) was observed in placental than peripheral blood while that of P. ovale was similar (1.8% in placental blood). Among the non-falciparum infected pregnant women with paired peripheral and placental samples, P. malariae infections in the placental blood was significantly higher than in the peripheral blood, suggesting a possible affinity of P. malariae for the placenta. However, no assoctiation of non-falciparum infections and the pregnancy outcomes was observed. Overall this study provided insights into the molecular epidemiology of Plasmodium spp. infection during pregnancy, indicating placental infection by non-falciparum Plasmodium and the lack of association of these infections with adverse pregnancy outcomes.

Plasmodium falciparum msp1 and msp2 genetic diversity and allele frequencies in parasites isolated from symptomatic malaria patients in Bobo-Dioulasso, Burkina Faso.

PubMed

Somé, Anyirékun Fabrice; Bazié, Thomas; Zongo, Issaka; Yerbanga, R Serge; Nikiéma, Frédéric; Neya, Cathérine; Taho, Liz Karen; Ouédraogo, Jean-Bosco

2018-05-30

In Burkina Faso, malaria remains the overall leading cause of morbidity and mortality accounting for 35.12% of consultations, 40.83% of hospitalizations and 37.5% of deaths. Genotyping of malaria parasite populations remains an important tool to determine the types and number of parasite clones in an infection. The present study aimed to evaluate the merozoite surface protein 1 (msp1) and merozoite surface protein 2 (msp2) genetic diversity and allele frequencies in Bobo-Dioulasso, Burkina Faso. Dried blood spots (DBS) were collected at baseline from patients with uncomplicated malaria in urban health centers in Bobo-Dioulasso. Parasite DNA was extracted using chelex-100 and species were identified using nested PCR. Plamodium falciparum msp1 and msp2 genes were amplified by nested polymerase chain reaction (PCR) and PCR products were analyzed by electrophoresis on a 2.5% agarose gel. Alleles were categorized according to their molecular weight. A total of 228 blood samples were analyzed out of which 227 (99.9%) were confirmed as P. falciparum-positive and one sample classified as mixed infection for P. malaria and P. falciparum. In msp1, the K1 allelic family was predominant with 77.4% (162/209) followed respectively by the MAD20 allelic family with 41.3% and R033 allelic family with 36%. In msp2, the 3D7 allelic family was the most frequently detected with 93.1 % compared to FC27 with 41.3%. Twenty-one different alleles were observed in msp1 with 9 alleles for K1, 8 alleles for MAD20 and 4 alleles for R033. In msp2, 25 individual alleles were detected with 10 alleles for FC27 and 15 alleles for 3D7. The mean multiplicity of falciparum infection was 1.95 with respectively 1.8 (1.76-1.83) and 2.1 (2.03-2.16) for msp1 and msp2 (P = 0.01). Our study showed high genetic diversity and allelic frequencies of msp1 and msp2 in Plasmodium falciparum isolates from symptomatic malaria patients in Bobo-Dioulasso.

Test characteristics of the SD FK80 Plasmodium falciparum/Plasmodium vivax malaria rapid diagnostic test in a non-endemic setting

PubMed Central

2009-01-01

Background The SD FK80 P.f/P.v Malaria Antigen Rapid Test (Standard Diagnostics, Korea) (FK80) is a three-band malaria rapid diagnostic test detecting Plasmodium falciparum histidine-rich protein-2 (HRP-2) and Plasmodium vivax-specific lactate dehydrogenase (Pv-pLDH). The present study assessed its performance in a non-endemic setting. Methods Stored blood samples (n = 416) from international travellers suspected of malaria were used, with microscopy corrected by PCR as the reference method. Samples infected by Plasmodium falciparum (n = 178), Plasmodium vivax (n = 99), Plasmodium ovale (n = 75) and Plasmodium malariae (n = 24) were included, as well as 40 malaria negative samples. Results Overall sensitivities for the diagnosis of P. falciparum and P. vivax were 91.6% (95% confidence interval (CI): 86.2% - 95.0%) and 75.8% (65.9% - 83.6%). For P. falciparum, sensitivity at parasite densities ≥ 100/μl was 94.6% (88.8% - 97.6%); for P. vivax, sensitivity at parasite densities ≥ 500/μl was 86.8% (75.4% - 93.4%). Four P. falciparum samples showed a Pv-pLDH line, three of them had parasite densities exceeding 50.000/μl. Two P. vivax samples, one P. ovale and one P. malariae sample showed a HRP-2 line. For the HRP-2 and Pv-pLDH lines, respectively 81.4% (136/167) and 55.8% (43/77) of the true positive results were read as medium or strong line intensities. The FK80 showed good reproducibility and reliability for test results and line intensities (kappa values for both exceeding 0.80). Conclusion The FK80 test performed satisfactorily in diagnosing P. falciparum and P. vivax infections in a non-endemic setting. PMID:19930609

Case Report: A Case of Plasmodium falciparum hrp2 and hrp3 Gene Mutation in Bangladesh.

PubMed

Nima, Maisha Khair; Hougard, Thomas; Hossain, Mohammad Enayet; Kibria, Mohammad Golam; Mohon, Abu Naser; Johora, Fatema Tuj; Rahman, Rajibur; Haque, Rashidul; Alam, Mohammad Shafiul

2017-10-01

Several species of Plasmodium are responsible for causing malaria in humans. Proper diagnoses are crucial to case management, because severity and treatment varies between species. Diagnoses can be made using rapid diagnostic tests (RDTs), which detect Plasmodium proteins. Plasmodium falciparum causes the most virulent cases of malaria, and P. falciparum histidine-rich protein 2 (PfHRP2) is a common target of falciparum malaria RDTs. Here we report a case in which a falciparum malaria patient in Bangladesh tested negative on PfHRP2-based RDTs. The negative results can be attributed to a deletion of part of the pfhrp2 gene and frameshift mutations in both pfhrp2 and pfhrp3 gene. This finding may have implications for malaria diagnostics and case management in Bangladesh and other regions of South Asia.

Test and Evaluation of Field-Deployable Infectious Disease Diagnostic Assays in Support of the Joint Biological Agent Identification and Diagnosis System (JBAIDS): Malaria (Plasmodium/JBAIDS)

DTIC Science & Technology

2012-05-31

plasmid and P . falciparum plasmid. The assay was 100% (17/17) concordant in testing using a diverse panel ofPiasmodium species and strains prepared...AFMSA O&M FY10 ‘Plasmodium Project’, existing Plasmodium genus, P . falciparum , and P . vivax TaqMan assays were proposed for transfer to the RAPID...using P . vivax plasmid and P . falciparum plasmid. The assay was 100% (17/17) concordant in testing using a diverse panel of Plasmodium species and

Population genetics of Plasmodium falciparum and Plasmodium vivax and asymptomatic malaria in Temotu Province, Solomon Islands

PubMed Central

2013-01-01

Background Temotu Province, Solomon Islands is progressing toward malaria elimination. A baseline survey conducted in 2008 showed that most Plasmodium infections in the province were of low parasite density and asymptomatic infections. To better understand mechanisms underlying these malaria transmission characteristics genetic diversity and relationships among Plasmodium falciparum and Plasmodium vivax populations in the province were examined. Methods Forty-five P. falciparum and 67 P. vivax samples collected in the 2008 baseline survey were successfully genotyped using eight P. falciparum and seven P. vivax microsatellite markers. Genetic diversity, relationships and distribution of both P. falciparum and P. vivax populations were analysed. Results Plasmodium falciparum population exhibited low diversity with 19 haplotypes identified and had closely related clusters indicating clonal expansion. Interestingly, a dominant haplotype was significantly associated with fever and high parasite density. In contrast, the P. vivax population was highly diverse with 58 haplotypes identified that were not closely related. Parasite populations between different islands in the province showed low genetic differentiation. Conclusion The low diversity and clonal population of P. falciparum population may partially account for clinical immunity developed against illness. However, it is possible that importation of a new P. falciparum strain was the major cause of illness. High diversity in P. vivax population and low relatedness between strains suggested clinical immunity to P. vivax may be maintained by different mechanisms. The genetic diversity, population structure and distribution of strains indicate that transmission of P. falciparum was low, but that of P. vivax was still high in 2008. These data will be useful for assessing changes in malaria transmission resulting from interventions. PMID:24261646

Efficacy and Tolerability Outcomes of a Phase II, Randomized, Open-Label, Multicenter Study of a New Water-Dispersible Pediatric Formulation of Dihydroartemisinin-Piperaquine for the Treatment of Uncomplicated Plasmodium falciparum Malaria in African Infants

PubMed Central

Gargano, Nicola; Madrid, Lola; Valentini, Giovanni; D'Alessandro, Umberto; Halidou, Tinto; Sirima, Sodiomon; Tshefu, Antoinette; Mtoro, Ali; Gesase, Samwel

2017-01-01

ABSTRACT Artemisinin combination therapies are considered the mainstay of malaria treatment, but pediatric-friendly formulations for the treatment of infants are scarce. We sought to evaluate the efficacy and safety of a new dispersible-tablet formulation of dihydroartemisinin/piperaquine phosphate (DHA/PQP) in comparison to the marketed tablet (Eurartesim) in the treatment of infants with uncomplicated Plasmodium falciparum malaria. Reported here are the results of a large phase II, randomized, open-label, multicenter trial conducted in African infants (6 to 12 months of age) from Mozambique, Burkina Faso, The Gambia, the Democratic Republic of the Congo, and Tanzania. Primary efficacy endpoint was the PCR-corrected adequate clinical and parasitological response (ACPR) at day 28. Analysis was performed for the intention-to-treat (ITT) and per-protocol (PP) populations. A total of 201 patients received the dispersible-tablet formulation, and 99 received the conventional one administered as crushed tablets. At day 28, the PCR-corrected ACPRs were 86.9% (ITT) and 98.3% (PP) in the dispersible-tablet group and 84.9% (ITT) and 100% (PP) in the crushed-tablet group. At day 42, these values were 85.9% (ITT) and 96.5% (PP) in the dispersible-tablet group and 82.8% (ITT) and 96.4% (PP) in the crushed-tablet group. The comparison between survival curves for time to new infections showed no statistically significant differences (P = 0.409). The safety and tolerability profile for the two groups was similar in terms of type and frequency of adverse events and was consistent with that expected in African infants with malaria. A standard 3-day treatment with the new dispersible DHA/PQP formulation is as efficacious as the currently used tablet in African infants and has a comparable safety profile. (This trial was registered at ClinicalTrials.gov under registration no. NCT01992900.) PMID:29061746

A randomized trial on effectiveness of artemether-lumefantrine versus artesunate plus amodiaquine for unsupervised treatment of uncomplicated Plasmodium falciparum malaria in Ghanaian children

PubMed Central

Kobbe, Robin; Klein, Philipp; Adjei, Samuel; Amemasor, Solomon; Thompson, William Nana; Heidemann, Hanna; Nielsen, Maja V; Vohwinkel, Julia; Hogan, Benedikt; Kreuels, Benno; Bührlen, Martina; Loag, Wibke; Ansong, Daniel; May, Jürgen

2008-01-01

Background Numerous trials have demonstrated high efficacy and safety of artemisinin-based combination therapy (ACT) under supervised treatment. In contrast, effectiveness studies comparing different types of ACT applied unsupervised are scarce. The aim of this study was to compare effectiveness, tolerability and acceptance of artesunate plus amodiaquine (ASAQ) against that of artemether-lumefantrine (AL) in Ghanaian children with uncomplicated Plasmodium falciparum malaria. Methods A randomized open-label trial was conducted at two district hospitals in the Ashanti region, Ghana, an area of intense malaria transmission. A total of 246 children under five years of age were randomly assigned to either ASAQ (Arsucam®) or AL (Coartem®). Study participants received their first weight-adjusted dose under supervision. After the parent/guardian was advised of times and mode of administration the respective three-day treatment course was completed unobserved at home. Follow-up visits were performed on days 3, 7, 14 and 28 to evaluate clinical and parasitological outcomes, adverse events, and haematological recovery. Length polymorphisms of variable regions of msp1 and msp2 were determined to differentiate recrudescences from reinfections. Acceptance levels of both treatment regimens were assessed by means of standardized interviews. Results Adequate clinical and parasitological responses after AL and ASAQ treatment were similar (88.3% and 91.7%, respectively). Interestingly, more late clinical failures until day 28 occurred in AL-treated children than in those who received ASAQ (17.5% and 7.3%, respectively; Hazard Ratio 2.41, 95% CI 1.00–5.79, p < 0.05). Haematological recovery and drug tolerability were not found to be significantly different in both study arms. The acceptance of treatment with ASAQ was higher than that with AL (rank-scores 10.6 and 10.3, respectively; p < 0.05). Conclusion Unobserved AL and ASAQ treatment showed high adequate clinical and parasitological responses, though AL was inferior in preventing late clinical failures. PMID:19099594

Efficacy and Tolerability Outcomes of a Phase II, Randomized, Open-Label, Multicenter Study of a New Water-Dispersible Pediatric Formulation of Dihydroartemisinin-Piperaquine for the Treatment of Uncomplicated Plasmodium falciparum Malaria in African Infants.

PubMed

Gargano, Nicola; Madrid, Lola; Valentini, Giovanni; D'Alessandro, Umberto; Halidou, Tinto; Sirima, Sodiomon; Tshefu, Antoinette; Mtoro, Ali; Gesase, Samwel; Bassat, Quique

2018-01-01

Artemisinin combination therapies are considered the mainstay of malaria treatment, but pediatric-friendly formulations for the treatment of infants are scarce. We sought to evaluate the efficacy and safety of a new dispersible-tablet formulation of dihydroartemisinin/piperaquine phosphate (DHA/PQP) in comparison to the marketed tablet (Eurartesim) in the treatment of infants with uncomplicated Plasmodium falciparum malaria. Reported here are the results of a large phase II, randomized, open-label, multicenter trial conducted in African infants (6 to 12 months of age) from Mozambique, Burkina Faso, The Gambia, the Democratic Republic of the Congo, and Tanzania. Primary efficacy endpoint was the PCR-corrected adequate clinical and parasitological response (ACPR) at day 28. Analysis was performed for the intention-to-treat (ITT) and per-protocol (PP) populations. A total of 201 patients received the dispersible-tablet formulation, and 99 received the conventional one administered as crushed tablets. At day 28, the PCR-corrected ACPRs were 86.9% (ITT) and 98.3% (PP) in the dispersible-tablet group and 84.9% (ITT) and 100% (PP) in the crushed-tablet group. At day 42, these values were 85.9% (ITT) and 96.5% (PP) in the dispersible-tablet group and 82.8% (ITT) and 96.4% (PP) in the crushed-tablet group. The comparison between survival curves for time to new infections showed no statistically significant differences ( P = 0.409). The safety and tolerability profile for the two groups was similar in terms of type and frequency of adverse events and was consistent with that expected in African infants with malaria. A standard 3-day treatment with the new dispersible DHA/PQP formulation is as efficacious as the currently used tablet in African infants and has a comparable safety profile. (This trial was registered at ClinicalTrials.gov under registration no. NCT01992900.). Copyright © 2017 Gargano et al.

Six-years monitoring the efficacy of the combination of artesunate and mefloquine for the treatment of uncomplicated falciparum malaria.

PubMed

Wattanakoon, Yupaporn; Chittamas, Sunee; Pornkulprasit, Vichitra; Kanda, Tozo; Thimasarn, Krongthong; Rojanawatsirivej, Chaiporn; Looareesuwan, Sornchai; Bunnag, Danai

2003-09-01

Plasmodium falciparum in Thailand is multi-drug resistant. In a previous study it was shown that artesunate and mefloquine were effective, as follow up, we monitored the efficacy of this regimen for six years. During 1997-2002, 516 adult male volunteer patients in Chanthaburi Province were enrolled (50 patients in the first year, 400 patients in 1998-2001 and 66 patients in 2002). The symptom complex and parasite count (thick blood film) were monitored on days 0, 1, 2, 7, 14, 21, 28, 35 and 42. The dosages used were artesunate (ATS) 150 mg and mefloquine (M) 750 mg at hour 0 and ATS 100 mg and M 500 mg at hour 24. Their ages ranged from 30-35 years and their mean body weights were 54-56 kg. The presenting symptoms were fever 100%, headache 97-100%, anorexia 78-90%, and nausea 28-40%. The geometric mean of parasitemia ranged from 7,357-12,750/mm3. Defervescence in one day was found in 42-76% of patients and 85-100% in 2 days. The sensitivity (S) ranged from 87-94% and RI resistance (recrudescence) ranged from 6-13%. Forty patients demonstrated RI type of response, 37 were cured after being retreated with the same dosage and another 3 patients were cured after the third course of treatment. The aggravated adverse effects included vomiting (8-20%), anorexia (1-41%) and diarrhea (0-16%). These side effects were mild and transient. The efficacy of the artesunate and mefloquine combination for the treatment of uncomplicated falciparum malaria was high. The RI type of response was possibly due to re-infection or multiple broods and not to drug resistance. The adverse effects of anorexia, nausea, vomiting and diarrhea were mild and transient for mefloquine. The combination can be used as stand by treatment in areas of multi-drug resistant falciparum malaria.

Molecular markers associated with resistance to commonly used antimalarial drugs among Plasmodium falciparum isolates from a malaria-endemic area in Taiz governorate-Yemen during the transmission season.

PubMed

Alareqi, Lina M Q; Mahdy, Mohammed A K; Lau, Yee-Ling; Fong, Mun-Yik; Abdul-Ghani, Rashad; Mahmud, Rohela

2016-10-01

Since 2005, artesunate (AS) plus sulfadoxine/pyrimethamine (SP) combination has been adopted as the first-line treatment for uncomplicated malaria in Yemen in response to the high level of Plasmodium falciparum resistance to chloroquine (CQ). Therefore, the aim of the present study was to determine the frequency distribution of molecular markers associated with resistance to CQ and AS plus SP combination among P. falciparum isolates from a malaria-endemic area in Taiz governorate, Yemen. Fifty P. falciparum isolates were collected during a cross-sectional study in Mawza district, Taiz, in the period from October 2013 to April 2014. The isolates were investigated for drug resistance-associated molecular markers in five genes, including P. falciparum CQ resistance transporter (pfcrt) 76T and P. falciparum multidrug resistance 1 (pfmdr1) 86Y as markers of resistance to CQ, mutations in the Kelch 13 (K13) propeller domain for resistance to AS, and P. falciparum dihydrofolate reductase (pfdhfr) and P. falciparum dihydropteroate synthase (pfdhps) genes for resistance to SP. Nested polymerase chain reaction was used to amplify target genes in DNA extracts of the isolates followed by restriction fragment length polymorphism for detecting 76T and 86Y mutations in pfcrt and pfmdr1, respectively, and by DNA sequencing for detecting mutations in K13, pfdhfr and pfdhps. All the investigated isolates from Mawza district were harboring the pfcrt 76T mutant and the pfmdr1 N86 wild-type alleles. The pfdhfr 51I/108N double mutant allele was found in 2.2% (1/45) of the isolates; however, no mutations were detected at codons 436, 437, 540, 581 and 613 of pfdhps. All P. falciparum isolates that were successfully sequenced (n=47) showed the K13 Y493, R539, I543 and C580 wild-type alleles. In conclusion, the pfcrt 76T mutant allele is fixed in the study area about six years after the official withdrawal of CQ, possibly indicating its over-the-counter availability and continued use as a self-medication in the study area. However, the almost predominant wild-type alleles of the genes associated with resistance to AS and SP among P. falciparum isolates in the present study indicates the sustained efficacy of the currently adopted first-line treatment of AS plus SP in the study area. Copyright © 2016 Elsevier B.V. All rights reserved.

Efficacy and safety of a combination of azithromycin and chloroquine for the treatment of uncomplicated Plasmodium falciparum malaria in two multi-country randomised clinical trials in African adults.

PubMed

Sagara, Issaka; Oduro, Abraham R; Mulenga, Modest; Dieng, Yemou; Ogutu, Bernhards; Tiono, Alfred B; Mugyenyi, Peter; Sie, Ali; Wasunna, Monique; Kain, Kevin C; Djimdé, Abdoulaye A; Sarkar, Shirsendu; Chandra, Richa; Robbins, Jeffery; Dunne, Michael W

2014-11-25

Given increasing rates of resistance to existing therapy, new options for treatment and prophylaxis of malaria are needed. Two randomised, comparative, non-inferiority studies were conducted in Africa, one double-blinded and one open-label. Adults with fever, a positive peripheral blood smear, and a positive rapid diagnostic test for Plasmodium falciparum were randomised in both studies to either azithromycin (AZ) 1,000 mg plus chloroquine (CQ) 600-mg base (AZCQ 1,000 mg) once daily for three days or mefloquine hydrochloride (MQ) 1,250 mg (split dose). In the first study, an additional regimen of AZ 500 mg plus CQ 600-mg base (AZCQ 500 mg) once daily for three days was included. All study participants were hospitalised until three consecutive daily blood smears were negative for asexual P. falciparum parasitaemia. Study participants were evaluated weekly for 42 days, with Day 28 polymerase chain reaction (PCR)-corrected parasitological clearance rate as primary endpoint. A total of 467 subjects were randomised in the two studies. At 28 days' follow-up, PCR-corrected parasitological clearance rates in the per protocol population in the first study were 101/103 (98%) with AZCQ 1,000 mg compared with 102/103 (99%) with MQ (95% confidence interval [CI]: -5.2, 3.3). The AZCQ 500-mg regimen was stopped during an interim study review (six [86%] clearance of seven evaluable; two lost to follow-up). In the second study, clearance rates were similar: AZCQ 1,000 mg 107/107 (100%) vs MQ 111/112 (99%; 95% CI: -1.8, 3.6). Among the participating countries, in vitro CQ resistance based on pfcrt mutation frequency in the baseline isolates across both studies ranged from 20.8% (Zambia) to 96.1% (Uganda). Serious adverse events (AEs; all causality) were observed more frequently with MQ compared with AZCQ (four vs one, respectively), though discontinuations for AEs were similar (four vs three, respectively). Common AEs in the AZ-containing arms included pruritus, vomiting, dizziness, and headache. Among adults with symptomatic uncomplicated falciparum malaria in Africa, the combination of AZ 1,000 mg and CQ 600-mg base once daily for three days resulted in Day 28 PCR-corrected parasitological clearance rates of ≥98% and was non-inferior to treatment with MQ. AZCQ was well tolerated. ClinicalTrials.gov identifiers NCT00082576 and NCT00367653.

Trafficking of the signature protein of intra-erythrocytic Plasmodium berghei-induced structures, IBIS1, to P. falciparum Maurer's clefts.

PubMed

Petersen, Wiebke; Matuschewski, Kai; Ingmundson, Alyssa

2015-01-01

Remodeling of the host red blood cell by Plasmodium falciparum is well established and crucial for infection and parasite virulence. Host cell modifications are not exclusive to human Plasmodium parasites and also occur in hepatocytes and erythrocytes infected with murine Plasmodium parasites. The recently described intra-erythrocytic P. berghei-induced structures (IBIS) share similarities to P. falciparum Maurer's clefts. It is shown here that a potential candidate IBIS1 homologue in P. falciparum, PfHYP12 (PF3D7_1301400), is partially exported into the erythrocyte cytoplasm. To analyze a potential similarity between IBIS and Maurer's clefts we expressed the signature protein of IBIS in P. falciparum parasites. Visualization of the tagged protein revealed that PbIBIS1 can be exported by P. falciparum and localizes to Maurer's clefts in P. falciparum-infected erythrocytes, which indicates that IBIS and Maurer's clefts may be evolutionarily conserved parasite-induced structures in infected erythrocytes. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

The Plasmodium falciparum transcriptome in severe malaria reveals altered expression of genes involved in important processes including surface antigen–encoding var genes

PubMed Central

Tonkin-Hill, Gerry Q.; Trianty, Leily; Noviyanti, Rintis; Nguyen, Hanh H. T.; Sebayang, Boni F.; Lampah, Daniel A.; Marfurt, Jutta; Cobbold, Simon A.; Rambhatla, Janavi S.; McConville, Malcolm J.; Rogerson, Stephen J.; Brown, Graham V.; Day, Karen P.; Price, Ric N.; Anstey, Nicholas M.

2018-01-01

Within the human host, the malaria parasite Plasmodium falciparum is exposed to multiple selection pressures. The host environment changes dramatically in severe malaria, but the extent to which the parasite responds to—or is selected by—this environment remains unclear. From previous studies, the parasites that cause severe malaria appear to increase expression of a restricted but poorly defined subset of the PfEMP1 variant, surface antigens. PfEMP1s are major targets of protective immunity. Here, we used RNA sequencing (RNAseq) to analyse gene expression in 44 parasite isolates that caused severe and uncomplicated malaria in Papuan patients. The transcriptomes of 19 parasite isolates associated with severe malaria indicated that these parasites had decreased glycolysis without activation of compensatory pathways; altered chromatin structure and probably transcriptional regulation through decreased histone methylation; reduced surface expression of PfEMP1; and down-regulated expression of multiple chaperone proteins. Our RNAseq also identified novel associations between disease severity and PfEMP1 transcripts, domains, and smaller sequence segments and also confirmed all previously reported associations between expressed PfEMP1 sequences and severe disease. These findings will inform efforts to identify vaccine targets for severe malaria and also indicate how parasites adapt to—or are selected by—the host environment in severe malaria. PMID:29529020

Plasmodium falciparum resistance to artemisinin-based combination therapies: A sword of Damocles in the path toward malaria elimination.

PubMed

Ouji, Manel; Augereau, Jean-Michel; Paloque, Lucie; Benoit-Vical, Françoise

2018-01-01

The use of artemisinin-based combination therapies (ACTs), which combine an artemisinin derivative with a partner drug, in the treatment of uncomplicated malaria has largely been responsible for the significant reduction in malaria-related mortality in tropical and subtropical regions. ACTs have also played a significant role in the 18% decline in the incidence of malaria cases from 2010 to 2016. However, this progress is seriously threatened by the reduced clinical efficacy of artemisinins, which is characterised by delayed parasitic clearance and a high rate of recrudescence, as reported in 2008 in Western Cambodia. Resistance to artemisinins has already spread to several countries in Southeast Asia. Furthermore, resistance to partner drugs has been shown in some instances to be facilitated by pre-existing decreased susceptibility to the artemisinin component of the ACT. A major concern is not only the spread of these multidrug-resistant parasites to the rest of Asia but also their possible appearance in Sub-Saharan Africa, the continent most affected by malaria, as has been the case in the past with parasite resistance to other antimalarial treatments. It is therefore essential to understand the acquisition of resistance to artemisinins by Plasmodium falciparum to adapt malaria treatment policies and to propose new therapeutic solutions. © M. Ouji et al., published by EDP Sciences, 2018.

Complement Receptor 1 Is a Sialic Acid-Independent Erythrocyte Receptor of Plasmodium falciparum

DTIC Science & Technology

2010-06-17

Pennsylvania State University College of Medicine, Hershey , Pennsylvania, United States of America Abstract Plasmodium falciparum is a highly lethal malaria...www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1000968 Zimmerli S, Edwards S, Ernst JD ( 1996 ) Selective receptor blockade...in field isolates. J Immunol 165: 6341–6346. 22. Baruch DI, Gormely JA, Ma C, Howard RJ, Pasloske BL ( 1996 ) Plasmodium falciparum erythrocyte

Evidence of non-Plasmodium falciparum malaria infection in Kédougou, Sénégal.

PubMed

Daniels, Rachel F; Deme, Awa Bineta; Gomis, Jules F; Dieye, Baba; Durfee, Katelyn; Thwing, Julie I; Fall, Fatou B; Ba, Mady; Ndiop, Medoune; Badiane, Aida S; Ndiaye, Yaye Die; Wirth, Dyann F; Volkman, Sarah K; Ndiaye, Daouda

2017-01-03

Expanded malaria control efforts in Sénégal have resulted in increased use of rapid diagnostic tests (RDT) to identify the primary disease-causing Plasmodium species, Plasmodium falciparum. However, the type of RDT utilized in Sénégal does not detect other malaria-causing species such as Plasmodium ovale spp., Plasmodium malariae, or Plasmodium vivax. Consequently, there is a lack of information about the frequency and types of malaria infections occurring in Sénégal. This study set out to better determine whether species other than P. falciparum were evident among patients evaluated for possible malaria infection in Kédougou, Sénégal. Real-time polymerase chain reaction speciation assays for P. vivax, P. ovale spp., and P. malariae were developed and validated by sequencing and DNA extracted from 475 Plasmodium falciparum-specific HRP2-based RDT collected between 2013 and 2014 from a facility-based sample of symptomatic patients from two health clinics in Kédougou, a hyper-endemic region in southeastern Sénégal, were analysed. Plasmodium malariae (n = 3) and P. ovale wallikeri (n = 2) were observed as co-infections with P. falciparum among patients with positive RDT results (n = 187), including one patient positive for all three species. Among 288 negative RDT samples, samples positive for P. falciparum (n = 24), P. ovale curtisi (n = 3), P. ovale wallikeri (n = 1), and P. malariae (n = 3) were identified, corresponding to a non-falciparum positivity rate of 2.5%. These findings emphasize the limitations of the RDT used for malaria diagnosis and demonstrate that non-P. falciparum malaria infections occur in Sénégal. Current RDT used for routine clinical diagnosis do not necessarily provide an accurate reflection of malaria transmission in Kédougou, Sénégal, and more sensitive and specific methods are required for diagnosis and patient care, as well as surveillance and elimination activities. These findings have implications for other malaria endemic settings where species besides P. falciparum may be transmitted and overlooked by control or elimination activities.

Genetic Analysis and Species Specific Amplification of the Artemisinin Resistance-Associated Kelch Propeller Domain in P. falciparum and P. vivax

PubMed Central

Talundzic, Eldin; Chenet, Stella M.; Goldman, Ira F.; Patel, Dhruviben S.; Nelson, Julia A.; Plucinski, Mateusz M.; Barnwell, John W.; Udhayakumar, Venkatachalam

2015-01-01

Plasmodium falciparum resistance to artemisinin has emerged in the Greater Mekong Subregion and now poses a threat to malaria control and prevention. Recent work has identified mutations in the kelch propeller domain of the P. falciparum K13 gene to be associated artemisinin resistance as defined by delayed parasite clearance and ex vivo ring stage survival assays. Species specific primers for the two most prevalent human malaria species, P. falciparum and P. vivax, were designed and tested on multiple parasite isolates including human, rodent, and non- humans primate Plasmodium species. The new protocol described here using the species specific primers only amplified their respective species, P. falciparum and P. vivax, and did not cross react with any of the other human malaria Plasmodium species. We provide an improved species specific PCR and sequencing protocol that could be effectively used in areas where both P. falciparum and P. vivax are circulating. To design this improved protocol, the kelch gene was analyzed and compared among different species of Plasmodium. The kelch propeller domain was found to be highly conserved across the mammalian Plasmodium species. PMID:26292024

Genetic Analysis and Species Specific Amplification of the Artemisinin Resistance-Associated Kelch Propeller Domain in P. falciparum and P. vivax.

PubMed

Talundzic, Eldin; Chenet, Stella M; Goldman, Ira F; Patel, Dhruviben S; Nelson, Julia A; Plucinski, Mateusz M; Barnwell, John W; Udhayakumar, Venkatachalam

2015-01-01

Plasmodium falciparum resistance to artemisinin has emerged in the Greater Mekong Subregion and now poses a threat to malaria control and prevention. Recent work has identified mutations in the kelch propeller domain of the P. falciparum K13 gene to be associated artemisinin resistance as defined by delayed parasite clearance and ex vivo ring stage survival assays. Species specific primers for the two most prevalent human malaria species, P. falciparum and P. vivax, were designed and tested on multiple parasite isolates including human, rodent, and non- humans primate Plasmodium species. The new protocol described here using the species specific primers only amplified their respective species, P. falciparum and P. vivax, and did not cross react with any of the other human malaria Plasmodium species. We provide an improved species specific PCR and sequencing protocol that could be effectively used in areas where both P. falciparum and P. vivax are circulating. To design this improved protocol, the kelch gene was analyzed and compared among different species of Plasmodium. The kelch propeller domain was found to be highly conserved across the mammalian Plasmodium species.

Plasmodium falciparum cerebral malaria complicated by disseminated intravascular coagulation and symmetrical peripheral gangrene: case report and review.

PubMed

Liechti, M E; Zumsteg, V; Hatz, C F R; Herren, T

2003-09-01

The case of a 56-year-old female tourist who survived cerebral Plasmodium falciparum malaria with disseminated intravascular coagulation and symmetrical peripheral gangrene, ultimately requiring amputation of her left-sided fingertips and toes, is reported. While symmetrical peripheral gangrene has been described rarely in Asian, African, and American patients with Plasmodium falciparum malaria and disseminated intravascular coagulation, no such case has been reported in travelers returning from endemic areas.

Mosquito Vectors and the Globalization of Plasmodium falciparum Malaria.

PubMed

Molina-Cruz, Alvaro; Zilversmit, Martine M; Neafsey, Daniel E; Hartl, Daniel L; Barillas-Mury, Carolina

2016-11-23

Plasmodium falciparum malaria remains a devastating public health problem. Recent discoveries have shed light on the origin and evolution of Plasmodium parasites and their interactions with their vertebrate and mosquito hosts. P. falciparum malaria originated in Africa from a single horizontal transfer between an infected gorilla and a human, and became global as the result of human migration. Today, P. falciparum malaria is transmitted worldwide by more than 70 different anopheline mosquito species. Recent studies indicate that the mosquito immune system can be a barrier to malaria transmission and that the P. falciparum Pfs47 gene allows the parasite to evade mosquito immune detection. Here, we review the origin and globalization of P. falciparum and integrate this history with analysis of the biology, evolution, and dispersal of the main mosquito vectors. This new perspective broadens our understanding of P. falciparum population structure and the dispersal of important parasite genetic traits.

Identification of resistance of Plasmodium falciparum to artesunate-mefloquine combination in an area along the Thai-Myanmar border: integration of clinico-parasitological response, systemic drug exposure, and in vitro parasite sensitivity

PubMed Central

2013-01-01

Background A markedly high failure rate of three-day artesunate-mefloquine was observed in the area along the Thai-Myanmar border. Methods Identification of Plasmodium falciparum isolates with intrinsic resistance to each component of the artesunate-mefloquine combination was analysed with integrated information on clinico-parasitological response, together with systemic drug exposure (area under blood/plasma concentration-time curves (AUC)) of dihydroartemisinin and mefloquine, and in vitro sensitivity of P. falciparum in a total of 17 out of 29 P. falciparum isolates from patients with acute uncomplicated falciparum malaria. Analysis of the contribution of in vitro parasite sensitivity and systemic drug exposure and relationship with pfmdr1 copy number in the group with sensitive response was performed in 21 of 69 cases. Results Identification of resistance and/or reduced intrinsic parasitocidal activity of artesunate and/or mefloquine without pharmacokinetic or other host-related factors were confirmed in six cases: one with reduced sensitivity to artesunate alone, two with resistance to mefloquine alone, and three with reduced sensitivity to artesunate combined with resistance to mefloquine. Resistance and/or reduced intrinsic parasitocidal activity of mefloquine/artesunate, together with contribution of pharmacokinetic factor of mefloquine and/or artesunate were identified in seven cases: two with resistance to mefloquine alone, and five with resistance to mefloquine combined with reduced sensitivity to artesunate. Pharmacokinetic factor alone contributed to recrudescence in three cases, all of which had inadequate whole blood mefloquine levels (AUC0-7days). Other host-related factors contributed to recrudescence in one case. Amplification of pfmdr1 (increasing of pfmdr1 copy number) is a related molecular marker of artesunate-mefloquine resistance and seems to be a suitable molecular marker to predict occurrence of recrudescence. Conclusions Despite the evidence of a low level of a decline in sensitivity of P. falciparum isolates to artemisinins in areas along the Thai-Myanmar border, artemisinin-based combination therapy (ACT) would be expected to remain the key anti-malarial drug for treatment of multidrug resistance P. falciparum. Continued monitoring and active surveillance of clinical efficacy of ACT, including identification of true artemisinin resistant parasites, is required for appropriate implementation of malaria control policy in this area. PMID:23898808

Antimalarial activity of artefenomel (OZ439), a novel synthetic antimalarial endoperoxide, in patients with Plasmodium falciparum and Plasmodium vivax malaria: an open-label phase 2 trial.

PubMed

Phyo, Aung Pyae; Jittamala, Podjanee; Nosten, François H; Pukrittayakamee, Sasithon; Imwong, Mallika; White, Nicholas J; Duparc, Stephan; Macintyre, Fiona; Baker, Mark; Möhrle, Jörg J

2016-01-01

Artefenomel (OZ439) is a novel synthetic trioxolane with improved pharmacokinetic properties compared with other antimalarial drugs with the artemisinin pharmacophore. Artefenomel has been generally well tolerated in volunteers at doses up to 1600 mg and is being developed as a partner drug in an antimalarial combination treatment. We investigated the efficacy, tolerability, and pharmacokinetics of artefenomel at different doses in patients with Plasmodium falciparum or Plasmodium vivax malaria. This phase 2a exploratory, open-label trial was done at the Hospital for Tropical Diseases, Bangkok, and the Shoklo Malaria Research Unit in Thailand. Adult patients with acute, uncomplicated P falciparum or P vivax malaria received artefenomel in a single oral dose (200 mg, 400 mg, 800 mg, or 1200 mg). The first cohort received 800 mg. Testing of a new dose of artefenomel in a patient cohort was decided on after safety and efficacy assessment of the preceding cohort. The primary endpoint was the natural log parasite reduction per 24 h. Definitive oral treatment was given at 36 h. This trial is registered with ClinicalTrials.gov, number NCT01213966. Between Oct 24, 2010, and May 25, 2012, 82 patients were enrolled (20 in each of the 200 mg, 400 mg, and 800 mg cohorts, and 21 in the 1200 mg cohort). One patient withdrew consent (before the administration of artefenomel) but there were no further dropouts. The parasite reduction rates per 24 h ranged from 0·90 to 1·88 for P falciparum, and 2·09 to 2·53 for P vivax. All doses were equally effective in both P falciparum and P vivax malaria, with median parasite clearance half-lives of 4·1 h (range 1·3-6·7) to 5·6 h (2·0-8·5) for P falciparum and 2·3 h (1·2-3·9) to 3·2 h (0·9-15·0) for P vivax. Maximum plasma concentrations, dose-proportional to 800 mg, occurred at 4 h (median). The estimated elimination half-life was 46-62 h. No serious drug-related adverse effects were reported; other adverse effects were generally mild and reversible, with the highest number in the 1200 mg cohort (17 [81%] patients with at least one adverse event). The most frequently reported adverse effect was an asymptomatic increase in plasma creatine phosphokinase concentration (200 mg, n=5; 400 mg, n=3; 800 mg, n=1; 1200 mg, n=3). Artefenomel is a new synthetic antimalarial peroxide with a good safety profile that clears parasitaemia rapidly in both P falciparum and P vivax malaria. Its long half-life suggests a possible use in a single-dose treatment in combination with other drugs. Bill & Melinda Gates Foundation, Wellcome Trust, and UK Department for International Development. Copyright © 2016 Phyo et al. Open Access article distributed under the terms of CC BY-NC-ND. Published by Elsevier Ltd.. All rights reserved.

Declining Transmission and Immunity to Malaria and Emerging Artemisinin Resistance in Thailand: A Longitudinal Study.

PubMed

Ataíde, Ricardo; Powell, Rosanna; Moore, Kerryn; McLean, Alistair; Phyo, Aung Pyae; Nair, Shalini; White, Marina; Anderson, Tim J; Beeson, James G; Simpson, Julie A; Nosten, Francois; Fowkes, Freya J I

2017-09-15

Reductions in malaria transmission decrease naturally acquired immunity, which may influence the emergence of Plasmodium falciparum artemisinin-resistant phenotypes and genotypes over time. Antibodies specific for P. falciparum antigens were determined in uncomplicated hyperparasitemic malaria patients over a 10-year period of declining malaria transmission and emerging artemisinin resistance in northwestern Thailand. We investigated the association between antibody levels and both parasite clearance time (PCt½) and artemisinin resistance-associated kelch13 genotypes over time. Immunity to P. falciparum declined prior to 2004, preceding the emergence of artemisinin resistance-associated genotypes and phenotypes (maximum mean change in antibody level per year: anti-MSP142 = -0.17; 95% confidence interval [CI] = -.31 to -.04; P = .01). In this period of declining immunity, and in the absence of kelch13 mutations, PCt½ increased. Between 2007 and 2011, levels of antibodies fluctuated, and higher antibody levels were associated with faster PCt½ (maximum yearly change in PCt½, in hours: EBA140rII = -0.39; 95% CI = -.61 to -.17; P < .001). Understanding the impact of changing transmission and immunity on the emergence of artemisinin resistance is important particularly as increased malaria control and elimination activities may enhance immunological conditions for the expansion of artemisinin-resistant P. falciparum. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Phase II trial in China of a new, rapidly-acting and effective oral antimalarial, CGP 56697, for the treatment of Plasmodium falciparum malaria.

PubMed

Jiao, X; Liu, G Y; Shan, C O; Zhao, X; Li, X W; Gathmann, I; Royce, C

1997-09-01

One hundred and two Chinese out-patients with naturally acquired, previously untreated, falciparum malaria were selected to evaluate the efficacy of a new combination anti-malaria therapy, CGP 56697 (artemether plus benflumetol). In this open non-comparative trial each patient received a combination of 80 mg artemether and 480 mg benflumetol given orally at 0, 8, 24 and 48 hours (total: 320 mg artemether, 1,920 mg benflumetol). Patients were kept for 28 days in a transmission-free hospital in an area with chloroquine resistant falciparum malaria to prevent reinfection and to aid diagnosis of recrudescence. Progress and possible adverse effects were monitored by blood film parasitology, blood biochemistry assays, urinalysis, ECG and X-ray. Ninety-eight of the 102 patients were shown to be free of infection at 28 days, a 96.1% cure rate. Parasite reduction at 24 hours was 99.4%. Time to effect complete parasite clearance ranged from 24 to 54 hours (median 30 hours). Time for fever clearance ranged from 6 to 78 hours (median 18 hours). Recrudescence was low (3.9%). No significant adverse side-effects were encountered. It is concluded that CGP 56697, a combination anti-malaria therapy of artemether with benflumetol, offered a rapid and highly effective treatment for acute uncomplicated falciparum malaria in an area of chloroquine-resistant malaria in China.

Paradoxical associations between soil-transmitted helminths and Plasmodium falciparum infection.

PubMed

Fernández-Niño, Julián A; Idrovo, Alvaro J; Cucunubá, Zulma M; Reyes-Harker, Patricia; Guerra, Ángela P; Moncada, Ligia I; López, Myriam C; Barrera, Sandra M; Cortés, Liliana J; Olivera, Mario; Nicholls, Rubén S

2012-11-01

Evidence on the comorbidity between soil-transmitted helminth infections and malaria is scarce and divergent. This study explored the interactions between soil-transmitted helminth infections and uncomplicated falciparum malaria in an endemic area of Colombia. A paired case-control study matched by sex, age and location in Tierralta, Cordoba, was done between January and September 2010. The incident cases were 68 patients with falciparum malaria and 178 asymptomatic controls. A questionnaire was used to gather information on sociodemographic variables. Additionally physical examinations were carried out, stool samples were analysed for intestinal parasites and blood samples for Ig E concentrations. We found associations between infection with hookworm (OR: 4.21; 95% CI: 1.68-11.31) and Ascaris lumbricoides (OR 0.43; 95% CI: 0.18-1.04) and the occurrence of falciparum malaria. The effects of soil-transmitted helminths on the occurrence of malaria were found to be paradoxical. While hookworm is a risk factor, A. lumbricoides has a protective effect. The findings suggest that, in addition to the comorbidity, the presence of common determinants of soil-transmitted helminth infections and malaria could also exist. While the biological mechanisms involved are not clear, public health policies aimed at the control of their common social and environmental determinants are suggested. Copyright © 2012 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

Genetic polymorphism of merozoite surface protein-1 and merozoite surface protein-2 in Plasmodium falciparum isolates from Brazzaville, Republic of Congo

PubMed Central

2011-01-01

Background The characterization of malaria parasite populations circulating in an area is part of site characterization, as a basis for evaluating the impact of malaria interventions on genetic diversity, parasite species, and multiplicity of infection. The present study was aimed at analysing genetic diversity of Plasmodium falciparum merozoite surface proteins 1 and 2 (MSP-1 and MSP-2) and to determine the multiplicity of infection in clinical isolates collected from children living in the Southern district of Brazzaville in the Republic of Congo. Methods A total of 125 isolates from patients with uncomplicated malaria attending Terinkyo and Madibou health centres were collected between January and June 2005 while evaluating the therapeutic efficacy of amodiaquine-artesunate combination. DNA was extracted and msp-1 and msp-2 genes were genotyped using allele-specific nested-PCR. Results Out of 468 distinct fragments detected, 15 msp-1 and 20 msp-2 genotypes were identified. For the msp-1 gene, K1 family was the predominant allelic type carried alone or in association with RO33 and Mad20 types, whereas the 3D7 family was the most prevalent in the msp-2 gene. Overall, the mean multiplicity of infection was 2.2. Out of 125 samples, 104 (83%) harboured more than one parasite genotype. There was no statistical significant difference in the multiplicity of infection by either sex or age of patients. However, a statistically significant correlation was found between parasite densities and the number of genotypes. Conclusion Polymorphism in P. falciparum clinical isolates from Brazzaville was high and mainly of multiple clones. The basis for the positive association between parasite densities and multiplicity of infection is discussed. PMID:21936949

Submicroscopic placental infection by non-falciparum Plasmodium spp.

PubMed Central

Doritchamou, Justin Y. A.; Akuffo, Richard A.; Moussiliou, Azizath; Luty, Adrian J. F.; Massougbodji, Achille; Deloron, Philippe

2018-01-01

Background Among the Plasmodium species that infect humans, adverse effects of P. falciparum and P. vivax have been extensively studied and reported with respect to poor outcomes particularly in first time mothers and in pregnant women living in areas with unstable malaria transmission. Although, other non-falciparum malaria infections during pregnancy have sometimes been reported, little is known about the dynamics of these infections during pregnancy. Methods and findings Using a quantitative PCR approach, blood samples collected from Beninese pregnant women during the first antenatal visit (ANV) and at delivery including placental blood were screened for Plasmodium spp. Risk factors associated with Plasmodium spp. infection during pregnancy were assessed as well as the relationships with pregnancy outcomes. P. falciparum was the most prevalent Plasmodium species detected during pregnancy, irrespective either of parity, of age or of season during which the infection occurred. Although no P. vivax infections were detected in this cohort, P. malariae (9.2%) and P. ovale (5.8%) infections were observed in samples collected during the first ANV. These non-falciparum infections were also detected in maternal peripheral blood (1.3% for P. malariae and 1.2% for P. ovale) at delivery. Importantly, higher prevalence of P. malariae (5.5%) was observed in placental than peripheral blood while that of P. ovale was similar (1.8% in placental blood). Among the non-falciparum infected pregnant women with paired peripheral and placental samples, P. malariae infections in the placental blood was significantly higher than in the peripheral blood, suggesting a possible affinity of P. malariae for the placenta. However, no assoctiation of non-falciparum infections and the pregnancy outcomes was observed Conclusions Overall this study provided insights into the molecular epidemiology of Plasmodium spp. infection during pregnancy, indicating placental infection by non-falciparum Plasmodium and the lack of association of these infections with adverse pregnancy outcomes. PMID:29432484

Efficacy and safety of artemisinin-naphthoquine versus dihydroartemisinin-piperaquine in adult patients with uncomplicated malaria: a multi-centre study in Indonesia

PubMed Central

2012-01-01

Background A practical and simple regimen for all malaria species is needed towards malaria elimination in Indonesia. It is worth to compare the efficacy and safety of a single dose of artemisinin-naphthoquine (AN) with a three-day regimen of dihydroartemisinin-piperaquine (DHP), the existing programme drug, in adults with uncomplicated symptomatic malaria. Methods This is a phase III, randomized, open label using sealed envelopes, multi-centre, comparative study between a single dose of AN and a three-day dose of DHP in Jayapura and Maumere. The modified WHO inclusion and exclusion criteria for efficacy study were used in this trial. A total of 401 eligible adult malaria subjects were hospitalized for three days and randomly treated with AN four tablets single dose on day 0 or DHP three to four tablets single daily dose for three days, and followed for 42 days for physical examination, thick and thin smears microscopy, and other necessary tests. The efficacy of drug was assessed by polymerase chain reaction (PCR) uncorrected and corrected. Results There were 153 Plasmodium falciparum, 158 Plasmodium vivax and 90 P. falciparum/P. vivax malaria. Mean of fever clearance times were similar, 13.0 ± 10.3 hours in AN and 11.3 ± 7.3 hours in DHP groups. The mean of parasite clearance times were longer in AN compared with DHP (28.0 ± 11.7 hours vs 25.5 ± 12.2 hours, p = 0.04). There were only 12 PCR-corrected P. falciparum late treatment failures: seven in AN and five in DHP groups. The PCR uncorrected and corrected on day −42 of adequate clinical and parasitological responses for treatment of any malaria were 93.7% (95% Cl: 90.3–97.2) and 96.3% (95% Cl: 93.6–99.0) in AN, 96.3% (95% Cl: 93.5–99.0) and 97.3% (95% Cl: 95.0–99.6) in DHP groups. Few and mild adverse events were reported. All the abnormal haematology and blood chemistry values had no clinical abnormality. Conclusion AN and DHP are confirmed very effective, safe and tolerate for treatment of any malaria. Both drugs are promising for multiple first-line therapy policies in Indonesia. PMID:22554203

Efficacy of Chloroquine as a first line agent in the treatment of uncomplicated malaria due to Plasmodium vivax in children and treatment practices in Pakistan: A Pilot study.

PubMed

Waqar, Talal; Khushdil, Arshad; Haque, Khalid

2016-01-01

To ascertain the efficacy of chloroquine as first line agent in treatment of uncomplicated malaria -caused by Plasmodium vivax in children---and to determine its current treatment practice in Pakistan. This pilot study was conducted at the Paediatrics Department of Combined Military Hospital (CMH), Lahore, Pakistan. Forty-eight children between six months and twelve years of age having positive blood film for Plasmodium vivax were included. They were treated with chloroquine as a drug of - choice. Efficacy of chloroquine was assessed by clinical response, absence of parasitaemia on day seven and twenty-eight after initiation of therapy. A survey was also conducted to determine the first line therapeutic choice of Paediatricians in the treatment of uncomplicated Plasmodium vivax malaria in children in Pakistan. The results showed 100% efficacy of chloroquine in treating uncomplicated malaria caused by Plasmodium vivax in children. Artemisin was preferred by 74.28% Paediatricians' in combination therapy as 1st line treatment. Guidelines proposed by Malaria Control Programme Pakistan (MCPP) in collaboration with World Health Organization (WHO) are comprehensive but not being adhered to. The recently reported resistance of Plasmodium vivax to artemisin should urge measures to implement WHO guidelines.

Characterization of blood dendritic and regulatory T cells in asymptomatic adults with sub-microscopic Plasmodium falciparum or Plasmodium vivax infection.

PubMed

Kho, Steven; Marfurt, Jutta; Handayuni, Irene; Pava, Zuleima; Noviyanti, Rintis; Kusuma, Andreas; Piera, Kim A; Burdam, Faustina H; Kenangalem, Enny; Lampah, Daniel A; Engwerda, Christian R; Poespoprodjo, Jeanne R; Price, Ric N; Anstey, Nicholas M; Minigo, Gabriela; Woodberry, Tonia

2016-06-21

Plasmodium falciparum and Plasmodium vivax infections compromise dendritic cell (DC) function and expand regulatory T (Treg) cells in both clinical disease (malaria) and experimental human sub-microscopic infection. Conversely, in asymptomatic microscopy-positive (patent) P. falciparum or P. vivax infection in endemic areas, blood DC increase or retain HLA-DR expression and Treg cells exhibit reduced activation, suggesting that DC and Treg cells contribute to the control of patent asymptomatic infection. The effect of sub-microscopic (sub-patent) asymptomatic Plasmodium infection on DC and Treg cells in malaria-endemic area residents remains unclear. In a cross-sectional household survey conducted in Papua, Indonesia, 162 asymptomatic adults were prospectively evaluated for DC and Treg cells using field-based flow cytometry. Of these, 161 individuals (99 %) were assessed retrospectively by polymerase chain reaction (PCR), 19 of whom had sub-microscopic infection with P. falciparum and 15 with sub-microscopic P. vivax infection. Flow cytometric data were re-analysed after re-grouping asymptomatic individuals according to PCR results into negative controls, sub-microscopic and microscopic parasitaemia to examine DC and Treg cell phenotype in sub-microscopic infection. Asymptomatic adults with sub-microscopic P. falciparum or P. vivax infection had DC HLA-DR expression and Treg cell activation comparable to PCR-negative controls. Sub-microscopic P. falciparum infection was associated with lower peripheral CD4(+) T cells and lymphocytes, however sub-microscopic Plasmodium infection had no apparent effect on DC sub-set number or Treg cell frequency. In contrast to the impairment of DC maturation/function and the activation of Treg cells seen with sub-microscopic parasitaemia in primary experimental human Plasmodium infection, no phenotypic evidence of dysregulation of DC and Treg cells was observed in asymptomatic sub-microscopic Plasmodium infection in Indonesian adults. This is consistent with DC and Treg cells retaining their functional capacity in sub-microscopic asymptomatic infection with P. falciparum or P. vivax in malaria-endemic areas.

African great apes are natural hosts of multiple related malaria species, including Plasmodium falciparum

PubMed Central

Prugnolle, Franck; Durand, Patrick; Neel, Cécile; Ollomo, Benjamin; Ayala, Francisco J.; Arnathau, Céline; Etienne, Lucie; Mpoudi-Ngole, Eitel; Nkoghe, Dieudonné; Leroy, Eric; Delaporte, Eric; Peeters, Martine; Renaud, François

2010-01-01

Plasmodium reichenowi, a chimpanzee parasite, was until very recently the only known close relative of Plasmodium falciparum, the most virulent agent of human malaria. Recently, Plasmodium gaboni, another closely related chimpanzee parasite, was discovered, suggesting that the diversity of Plasmodium circulating in great apes in Africa might have been underestimated. It was also recently shown that P. reichenowi is a geographically widespread and genetically diverse chimpanzee parasite and that the world diversity of P. falciparum is fully included within the much broader genetic diversity of P. reichenowi. The evidence indicates that all extant populations of P. falciparum originated from P. reichenowi, likely by a single transfer from chimpanzees. In this work, we have studied the diversity of Plasmodium species infecting chimpanzees and gorillas in Central Africa (Cameroon and Gabon) from both wild-living and captive animals. The studies in wild apes used noninvasive sampling methods. We confirm the presence of P. reichenowi and P. gaboni in wild chimpanzees. Moreover, our results reveal the existence of an unexpected genetic diversity of Plasmodium lineages circulating in gorillas. We show that gorillas are naturally infected by two related lineages of parasites that have not been described previously, herein referred to as Plasmodium GorA and P. GorB, but also by P. falciparum, a species previously considered as strictly human specific. The continuously increasing contacts between humans and primate populations raise concerns about further reciprocal host transfers of these pathogens. PMID:20133889

Emergence of FY*Anull in a Plasmodium vivax-endemic region of Papua New Guinea

PubMed Central

Zimmerman, Peter A.; Woolley, Ian; Masinde, Godfred L.; Miller, Stephanie M.; McNamara, David T.; Hazlett, Fred; Mgone, Charles S.; Alpers, Michael P.; Genton, Blaise; Boatin, B. A.; Kazura, James W.

1999-01-01

In Papua New Guinea (PNG), numerous blood group polymorphisms and hemoglobinopathies characterize the human population. Human genetic polymorphisms of this nature are common in malarious regions, and all four human malaria parasites are holoendemic below 1500 meters in PNG. At this elevation, a prominent condition characterizing Melanesians is α+-thalassemia. Interestingly, recent epidemiological surveys have demonstrated that α+-thalassemia is associated with increased susceptibility to uncomplicated malaria among young children. It is further proposed that α+-thalassemia may facilitate so-called “benign” Plasmodium vivax infection to act later in life as a “natural vaccine” against severe Plasmodium falciparum malaria. Here, in a P. vivax-endemic region of PNG where the resident Abelam-speaking population is characterized by a frequency of α+-thalassemia ≥0.98, we have discovered the mutation responsible for erythrocyte Duffy antigen-negativity (Fy[a−b−]) on the FY*A allele. In this study population there were 23 heterozygous and no homozygous individuals bearing this new allele (allele frequency, 23/1062 = 0.022). Flow cytometric analysis illustrated a 2-fold difference in erythroid-specific Fy-antigen expression between heterozygous (FY*A/FY*Anull) and homozygous (FY*A/FY*A) individuals, suggesting a gene-dosage effect. In further comparisons, we observed a higher prevalence of P. vivax infection in FY*A/FY*A (83/508 = 0.163) compared with FY*A/FY*Anull (2/23 = 0.087) individuals (odds ratio = 2.05, 95% confidence interval = 0.47–8.91). Emergence of FY*Anull in this population suggests that P. vivax is involved in selection of this erythroid polymorphism. This mutation would ultimately compromise α+-thalassemia/P. vivax-mediated protection against severe P. falciparum malaria. PMID:10570183

Plasmodium falciparum in the southeastern Atlantic forest: a challenge to the bromeliad-malaria paradigm?

PubMed

Laporta, Gabriel Zorello; Burattini, Marcelo Nascimento; Levy, Debora; Fukuya, Linah Akemi; de Oliveira, Tatiane Marques Porangaba; Maselli, Luciana Morganti Ferreira; Conn, Jan Evelyn; Massad, Eduardo; Bydlowski, Sergio Paulo; Sallum, Maria Anice Mureb

2015-04-25

Recently an unexpectedly high prevalence of Plasmodium falciparum was found in asymptomatic blood donors living in the southeastern Brazilian Atlantic forest. The bromeliad-malaria paradigm assumes that transmission of Plasmodium vivax and Plasmodium malariae involves species of the subgenus Kerteszia of Anopheles and only a few cases of P. vivax malaria are reported annually in this region. The expectations of this paradigm are a low prevalence of P. vivax and a null prevalence of P. falciparum. Therefore, the aim of this study was to verify if P. falciparum is actively circulating in the southeastern Brazilian Atlantic forest remains. In this study, anophelines were collected with Shannon and CDC-light traps in seven distinct Atlantic forest landscapes over a 4-month period. Field-collected Anopheles mosquitoes were tested by real-time PCR assay in pools of ten, and then each mosquito from every positive pool, separately for P. falciparum and P. vivax. Genomic DNA of P. falciparum or P. vivax from positive anophelines was then amplified by traditional PCR for sequencing of the 18S ribosomal DNA to confirm Plasmodium species. Binomial probabilities were calculated to identify non-random results of the P. falciparum-infected anopheline findings. The overall proportion of anophelines naturally infected with P. falciparum was 4.4% (21/480) and only 0.8% (4/480) with P. vivax. All of the infected mosquitoes were found in intermixed natural and human-modified environments and most were Anopheles cruzii (22/25 = 88%, 18 P. falciparum plus 4 P. vivax). Plasmodium falciparum was confirmed by sequencing in 76% (16/21) of positive mosquitoes, whereas P. vivax was confirmed in only 25% (1/4). Binomial probabilities suggest that P. falciparum actively circulates throughout the region and that there may be a threshold of the forested over human-modified environment ratio upon which the proportion of P. falciparum-infected anophelines increases significantly. These results show that P. falciparum actively circulates, in higher proportion than P. vivax, among Anopheles mosquitoes of fragments of the southeastern Brazilian Atlantic forest. This finding challenges the classical bromeliad-malaria paradigm, which considers P. vivax circulation as the driver for the dynamics of residual malaria transmission in this region.

Pooled-DNA sequencing identifies genomic regions of selection in Nigerian isolates of Plasmodium falciparum.

PubMed

Oyebola, Kolapo M; Idowu, Emmanuel T; Olukosi, Yetunde A; Awolola, Taiwo S; Amambua-Ngwa, Alfred

2017-06-29

The burden of falciparum malaria is especially high in sub-Saharan Africa. Differences in pressure from host immunity and antimalarial drugs lead to adaptive changes responsible for high level of genetic variations within and between the parasite populations. Population-specific genetic studies to survey for genes under positive or balancing selection resulting from drug pressure or host immunity will allow for refinement of interventions. We performed a pooled sequencing (pool-seq) of the genomes of 100 Plasmodium falciparum isolates from Nigeria. We explored allele-frequency based neutrality test (Tajima's D) and integrated haplotype score (iHS) to identify genes under selection. Fourteen shared iHS regions that had at least 2 SNPs with a score > 2.5 were identified. These regions code for genes that were likely to have been under strong directional selection. Two of these genes were the chloroquine resistance transporter (CRT) on chromosome 7 and the multidrug resistance 1 (MDR1) on chromosome 5. There was a weak signature of selection in the dihydrofolate reductase (DHFR) gene on chromosome 4 and MDR5 genes on chromosome 13, with only 2 and 3 SNPs respectively identified within the iHS window. We observed strong selection pressure attributable to continued chloroquine and sulfadoxine-pyrimethamine use despite their official proscription for the treatment of uncomplicated malaria. There was also a major selective sweep on chromosome 6 which had 32 SNPs within the shared iHS region. Tajima's D of circumsporozoite protein (CSP), erythrocyte-binding antigen (EBA-175), merozoite surface proteins - MSP3 and MSP7, merozoite surface protein duffy binding-like (MSPDBL2) and serine repeat antigen (SERA-5) were 1.38, 1.29, 0.73, 0.84 and 0.21, respectively. We have demonstrated the use of pool-seq to understand genomic patterns of selection and variability in P. falciparum from Nigeria, which bears the highest burden of infections. This investigation identified known genomic signatures of selection from drug pressure and host immunity. This is evidence that P. falciparum populations explore common adaptive strategies that can be targeted for the development of new interventions.

Out of Africa: origins and evolution of the human malaria parasites Plasmodium falciparum and Plasmodium vivax.

PubMed

Loy, Dorothy E; Liu, Weimin; Li, Yingying; Learn, Gerald H; Plenderleith, Lindsey J; Sundararaman, Sesh A; Sharp, Paul M; Hahn, Beatrice H

2017-02-01

Plasmodium falciparum and Plasmodium vivax account for more than 95% of all human malaria infections, and thus pose a serious public health challenge. To control and potentially eliminate these pathogens, it is important to understand their origins and evolutionary history. Until recently, it was widely believed that P. falciparum had co-evolved with humans (and our ancestors) over millions of years, whilst P. vivax was assumed to have emerged in southeastern Asia following the cross-species transmission of a parasite from a macaque. However, the discovery of a multitude of Plasmodium spp. in chimpanzees and gorillas has refuted these theories and instead revealed that both P. falciparum and P. vivax evolved from parasites infecting wild-living African apes. It is now clear that P. falciparum resulted from a recent cross-species transmission of a parasite from a gorilla, whilst P. vivax emerged from an ancestral stock of parasites that infected chimpanzees, gorillas and humans in Africa, until the spread of the protective Duffy-negative mutation eliminated P. vivax from human populations there. Although many questions remain concerning the biology and zoonotic potential of the P. falciparum- and P. vivax-like parasites infecting apes, comparative genomics, coupled with functional parasite and vector studies, are likely to yield new insights into ape Plasmodium transmission and pathogenesis that are relevant to the treatment and prevention of human malaria. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Imported Malaria in Turkey: The Importance of Diagnosis and Treatment of Plasmodium falciparum/Plasmodium vivax Mixed Infection.

PubMed

Tünger, Özlem; Çakmak, Akide; Özbilgin, Ahmet; Tunalı, Varol; Çetin, Çiğdem Banu

2018-05-21

The most common types of malaria in the world are Plasmodium vivax and P. falciparum. In countries where both species are endemic, P. vivax and P. falciparum coinfection also occurs. Thus, the possibility of mixed malaria in Turkey should always be considered in cases with a traveling history to these countries. Here, we report a case of P. vivax/P. falciparum mixed infection that was diagnosed as P. falciparum malaria in Ethiopia. However, the administered treatment was inadequate, and infection recurred because of the miss in the diagnosis of P. vivax malaria, for which an effective drug for hypnozoites was not administered. This case report emphasizes the importance of diagnosis, correct and adequate treatment of infections, and a close follow-up of diseases.

3-Halo Chloroquine Derivatives Overcome Plasmodium falciparum Chloroquine Resistance Transporter-Mediated Drug Resistance in P. falciparum.

PubMed

Edaye, Sonia; Tazoo, Dagobert; Bohle, D Scott; Georges, Elias

2015-12-01

Polymorphism in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) was shown to cause chloroquine resistance. In this report, we examined the antimalarial potential of novel 3-halo chloroquine derivatives (3-chloro, 3-bromo, and 3-iodo) against chloroquine-susceptible and -resistant P. falciparum. All three derivatives inhibited the proliferation of P. falciparum; with 3-iodo chloroquine being most effective. Moreover, 3-iodo chloroquine was highly effective at potentiating and reversing chloroquine toxicity of drug-susceptible and -resistant P. falciparum. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Origin of the human malaria parasite Plasmodium falciparum in gorillas

PubMed Central

Liu, Weimin; Li, Yingying; Learn, Gerald H.; Rudicell, Rebecca S.; Robertson, Joel D.; Keele, Brandon F.; Ndjango, Jean-Bosco N.; Sanz, Crickette M.; Morgan, David B.; Locatelli, Sabrina; Gonder, Mary K.; Kranzusch, Philip J.; Walsh, Peter D.; Delaporte, Eric; Mpoudi-Ngole, Eitel; Georgiev, Alexander V.; Muller, Martin N.; Shaw, George M.; Peeters, Martine; Sharp, Paul M.; Rayner, Julian C.; Hahn, Beatrice H.

2010-01-01

Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here, we developed a novel polymerase chain reaction based single genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in fecal samples of wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed, and almost always comprised of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from western gorillas was comprised of parasites that were nearly identical to P. falciparum. In phylogenetic analyses of full-length mitochondrial sequences, human P. falciparum formed a monophyletic lineage within the gorilla parasite radiation. These findings indicate that P. falciparum is of gorilla and not of chimpanzee, bonobo or ancient human origin. PMID:20864995

Apoptosis and dysfunction of blood dendritic cells in patients with falciparum and vivax malaria

PubMed Central

Woodberry, Tonia; Kienzle, Vivian; McPhun, Virginia; Minigo, Gabriela; Lampah, Daniel A.; Kenangalem, Enny; Engwerda, Christian; López, J. Alejandro; Anstey, Nicholas M.

2013-01-01

Malaria causes significant morbidity worldwide and a vaccine is urgently required. Plasmodium infection causes considerable immune dysregulation, and elicitation of vaccine immunity remains challenging. Given the central role of dendritic cells (DCs) in initiating immunity, understanding their biology during malaria will improve vaccination outcomes. Circulating DCs are particularly important, as they shape immune responses in vivo and reflect the functional status of other subpopulations. We performed cross-sectional and longitudinal assessments of the frequency, phenotype, and function of circulating DC in 67 Papuan adults during acute uncomplicated P. falciparum, P. vivax, and convalescent P. falciparum infections. We demonstrate that malaria patients display a significant reduction in circulating DC numbers and the concurrent accumulation of immature cells. Such alteration is associated with marked levels of spontaneous apoptosis and impairment in the ability of DC to mature, capture, and present antigens to T cells. Interestingly, sustained levels of plasma IL-10 were observed in patients with acute infection and were implicated in the induction of DC apoptosis. DC apoptosis was reversed upon IL-10 blockade, and DC function recovered when IL-10 levels returned to baseline by convalescence. Our data provide key information on the mechanisms behind DC suppression during malaria and will assist in developing strategies to better harness DC’s immunotherapeutic potential. PMID:23835848

Use of buffy coat thick films in detecting malaria parasites in patients with negative conventional thick films.

PubMed

Duangdee, Chatnapa; Tangpukdee, Noppadon; Krudsood, Srivicha; Wilairatana, Polrat

2012-04-01

To determine the frequency of malaria parasite detection from the buffy coat blood films by using capillary tube in falciparum malaria patients with negative conventional thick films. Thirty six uncomplicated falciparum malaria patients confirmed by conventional thick and thin films were included in the study. The patients were treated with artemisinin combination therapy at Hospital for Tropical Diseases, Bangkok, Thailand for 28 day. Fingerpricks for conventional blood films were conducted every 6 hours until negative parasitemia, then daily fingerpricks for parasite checks were conducted until the patients were discharged from hospital. Blood samples were also concurrently collected in 3 heparinized capillary tubes at the same time of fingerpricks for conventional blood films when the prior parasitemia was negative on thin films and parasitemia was lower than 50 parasites/200 white blood cells by thick film. The first negative conventional thick films were compared with buffy coat thick films for parasite identification. Out of 36 patients with thick films showing negative for asexual forms of parasites, buffy coat films could detect remaining 10 patients (27.8%) with asexual forms of Plasmodium falciparum. The study shows that buffy coat thick films are useful and can detect malarial parasites in 27.8% of patients whose conventional thick films show negative parasitemia.

Non-falciparum malaria infections in pregnant women in West Africa.

PubMed

Williams, John; Njie, Fanta; Cairns, Matthew; Bojang, Kalifa; Coulibaly, Sheick Oumar; Kayentao, Kassoum; Abubakar, Ismaela; Akor, Francis; Mohammed, Khalifa; Bationo, Richard; Dabira, Edgar; Soulama, Alamissa; Djimdé, Moussa; Guirou, Etienne; Awine, Timothy; Quaye, Stephen L; Ordi, Jaume; Doumbo, Ogobara; Hodgson, Abraham; Oduro, Abraham; Magnussen, Pascal; Ter Kuile, Feiko O; Woukeu, Arouna; Milligan, Paul; Tagbor, Harry; Greenwood, Brian; Chandramohan, Daniel

2016-01-29

Non-Plasmodium falciparum malaria infections are found in many parts of sub-Saharan Africa but little is known about their importance in pregnancy. Blood samples were collected at first antenatal clinic attendance from 2526 women enrolled in a trial of intermittent screening and treatment of malaria in pregnancy (ISTp) versus intermittent preventive treatment (IPTp) conducted in Burkina Faso, The Gambia, Ghana and Mali. DNA was extracted from blood spots and tested for P. falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium ovale using a nested PCR test. Risk factors for a non-falciparum malaria infection were investigated and the influence of these infections on the outcome of pregnancy was determined. P. falciparum infection was detected frequently (overall prevalence by PCR: 38.8 %, [95 % CI 37.0, 40.8]), with a prevalence ranging from 10.8 % in The Gambia to 56.1 % in Ghana. Non-falciparum malaria infections were found only rarely (overall prevalence 1.39 % [95 % CI 1.00, 1.92]), ranging from 0.17 % in the Gambia to 3.81 % in Mali. Ten non-falciparum mono-infections and 25 mixed falciparum and non-falciparum infections were found. P. malariae was the most frequent non-falciparum infection identified; P. vivax was detected only in Mali. Only four of the non-falciparum mono-infections were detected by microscopy or rapid diagnostic test. Recruitment during the late rainy season and low socio-economic status were associated with an increased risk of non-falciparum malaria as well as falciparum malaria. The outcome of pregnancy did not differ between women with a non-falciparum malaria infection and those who were not infected with malaria at first ANC attendance. Non-falciparum infections were infrequent in the populations studied, rarely detected when present as a mono-infection and unlikely to have had an important impact on the outcome of pregnancy in the communities studied due to the small number of women infected with non-falciparum parasites.

Associations Between Helminth Infections, Plasmodium falciparum Parasite Carriage and Antibody Responses to Sexual and Asexual Stage Malarial Antigens.

PubMed

Ateba-Ngoa, Ulysse; Jones, Sophie; Zinsou, Jeannot Fréjus; Honkpehedji, Josiane; Adegnika, Ayola Akim; Agobe, Jean-Claude Dejon; Massinga-Loembe, Marguerite; Mordmüller, Benjamin; Bousema, Teun; Yazdanbakhsh, Maria

2016-08-03

Infections with helminths and Plasmodium spp. overlap in their geographical distribution. It has been postulated that helminth infections may influence malarial transmission by altering Plasmodium falciparum gametocytogenesis. This cross-sectional study assessed the effect of helminth infections on P. falciparum gametocyte carriage and on humoral immune responses to sexual stage antigens in Gabon. Schistosoma haematobium and filarial infections as well as P. falciparum asexual forms and gametocyte carriage were determined. The antibody responses measured were to sexual (Pfs230, Pfs48/45) and asexual P. falciparum antigens (AMA1, MSP1, and GLURP). A total of 287 subjects were included. The prevalence of microscopically detectable P. falciparum asexual parasites was higher in S. haematobium-infected subjects in comparison to their uninfected counterparts (47% versus 26%, P = 0.003), but this was not different when filarial infections were considered. Plasmodium falciparum gametocyte carriage was similar between Schistosoma- or filaria-infected and uninfected subjects. We observed a significant decrease of Pfs48/45 immunoglobulin G titer in S. haematobium-infected subjects (P = 0.037), whereas no difference was seen for Pfs230 antibody titer, nor for antibodies to AMA1, MSP1, or GLURP. Our findings suggest an effect of S. haematobium on antibody responses to some P. falciparum gametocyte antigens that may have consequences for transmission-blocking immunity. © The American Society of Tropical Medicine and Hygiene.

Treatment of acute uncomplicated falciparum malaria with artemether-lumefantrine in nonimmune populations: a safety, efficacy, and pharmacokinetic study.

PubMed

Hatz, Christoph; Soto, Jaime; Nothdurft, Hans Dieter; Zoller, Thomas; Weitzel, Thomas; Loutan, Louis; Bricaire, Francois; Gay, Frederick; Burchard, Gerd-Dieter; Andriano, Kim; Lefèvre, Gilbert; De Palacios, Patricia Ibarra; Genton, Blaise

2008-02-01

The efficacy and safety of artemether-lumefantrine for the treatment of malaria in nonimmune populations are not well defined. In this study, 165 nonimmune patients from Europe and non-malarious areas of Colombia with acute, uncomplicated falciparum malaria or mixed infection including P. falciparum were treated with the six-dose regimen of artemether-lumefantrine. The parasitologic cure rate at 28 days was 96.0% for the per protocol population (119/124 patients). Median times to parasite clearance and fever clearance were 41.5 and 36.8 hours, respectively. No patient had gametocytes after Day 7. Treatment was well tolerated; most adverse events were mild to moderate and seemed to be related to malaria. There were few serious adverse events, none of which were considered to be drug-related. No significant effects on ECG or laboratory parameters were observed. In conclusion, the six-dose regimen of artemether-lumefantrine was effective and well tolerated in the treatment of acute uncomplicated falciparum malaria in nonimmune patients.

Prevalence of mutation and phenotypic expression associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum and Plasmodium vivax.

PubMed

Zakai, Haytham A; Khan, Wajihullah; Asma, Umme

2013-09-01

Therapeutic efficacy of sulfadoxine-pyrimethamine (SP), which is commonly used to treat falciparum malaria, was assessed in isolates of Plasmodium falciparum (Welch, 1897) and Plasmodium vivax (Grassi et Feletti, 1890) ofAligarh, Uttar Pradesh, North India and Taif, Saudi Arabia during 2011-2012. Both the species showed mutations in dihydrofolate reductase (DHFR) enzyme as they have common biochemical drug targets. Mutation rate for pfdhfr was higher compared to pvdhfr because the drug was mainly given to treat falciparum malaria. Since both the species coexist, P. vivax was also exposed to SP due to faulty species diagnosis or medication without specific diagnosis. Low level of mutations against SP in P. falciparum of Saudi isolates indicates that the SP combination is still effective for the treatment of falciparum malaria. Since SP is used as first-line of treatment because of high level of resistance against chloroquine (CQ), it may result in spread of higher level of mutations resulting in drug resistance and treatment failure in near future. Therefore, to avoid further higher mutations in the parasite, use of better treatment regimens such as artesunate combination therapy must be introduced against SP combination.

Dihydroartemisinin–piperaquine resistance in Plasmodium falciparum malaria in Cambodia: a multisite prospective cohort study

PubMed Central

Amaratunga, Chanaki; Lim, Pharath; Suon, Seila; Sreng, Sokunthea; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Dek, Dalin; Try, Vorleak; Amato, Roberto; Blessborn, Daniel; Song, Lijiang; Tullo, Gregory S; Fay, Michael P; Anderson, Jennifer M; Tarning, Joel; Fairhurst, Rick M

2016-01-01

Background Artemisinin resistance in Plasmodium falciparum threatens to reduce the efficacy of artemisinin combination therapies (ACTs), thus compromising global efforts to eliminate malaria. Recent treatment failures with dihydroartemisinin-piperaquine, the current first-line ACT in Cambodia, suggest that piperaquine resistance may be emerging in this country. We explored the relation between artemisinin resistance and dihydroartemisinin–piperaquine failures, and sought to confirm the presence of piperaquine-resistant P falciparum infections in Cambodia. Methods In this prospective cohort study, we enrolled patients aged 2–65 years with uncomplicated P falciparum malaria in three Cambodian provinces: Pursat, Preah Vihear, and Ratanakiri. Participants were given standard 3-day courses of dihydroartemisinin–piperaquine. Peripheral blood parasite densities were measured until parasites cleared and then weekly to 63 days. The primary outcome was recrudescent P falciparum parasitaemia within 63 days. We measured piperaquine plasma concentrations at baseline, 7 days, and day of recrudescence. We assessed phenotypic and genotypic markers of drug resistance in parasite isolates. The study is registered with ClinicalTrials.gov, number NCT01736319. Findings Between Sept 4, 2012, and Dec 31, 2013, we enrolled 241 participants. In Pursat, where artemisinin resistance is entrenched, 37 (46%) of 81 patients had parasite recrudescence. In Preah Vihear, where artemisinin resistance is emerging, ten (16%) of 63 patients had recrudescence and in Ratanakiri, where artemisinin resistance is rare, one (2%) of 60 patients did. Patients with recrudescent P falciparum infections were more likely to have detectable piperaquine plasma concentrations at baseline compared with non-recrudescent patients, but did not differ significantly in age, initial parasite density, or piperaquine plasma concentrations at 7 days. Recrudescent parasites had a higher prevalence of kelch13 mutations, higher piperaquine 50% inhibitory concentration (IC50) values, and lower mefloquine IC50 values; none had multiple pfmdr1 copies, a genetic marker of mefloquine resistance. Interpretation Dihydroartemisinin–piperaquine failures are caused by both artemisinin and piperaquine resistance, and commonly occur in places where dihydroartemisinin–piperaquine has been used in the private sector. In Cambodia, artesunate plus mefloquine may be a viable option to treat dihydroartemisinin–piperaquine failures, and a more effective first-line ACT in areas where dihydroartemisinin–piperaquine failures are common. The use of single low-dose primaquine to eliminate circulating gametocytes is needed in areas where artemisinin and ACT resistance is prevalent. Funding National Institute of Allergy and Infectious Diseases. PMID:26774243

Reemergence of chloroquine-sensitive pfcrt K76 Plasmodium falciparum genotype in southeastern Cameroon.

PubMed

Ndam, Nicaise Tuikue; Basco, Leonardo K; Ngane, Vincent Foumane; Ayouba, Ahidjo; Ngolle, Eitel Mpoudi; Deloron, Philippe; Peeters, Martine; Tahar, Rachida

2017-03-27

Chloroquine had been used extensively during the last five decades in Cameroon. Its decreasing clinical effectiveness, supported by high proportions of clinical isolates carrying the mutant pfcrt haplotype (CVIET), led the health authorities to resort to amodiaquine monotherapy in 2002 and artemisinin-based combination therapy (ACT) in 2004 (artesunate-amodiaquine, with artemether-lumefantrine as an alternative since 2006) as the first-line treatment of uncomplicated malaria. The aim of the present study was to investigate whether the withdrawal of chloroquine was associated with a reduction in pfcrt mutant parasite population and reemergence of chloroquine-sensitive parasites in southeastern Cameroon between 2003 and 2012. The frequency of pfcrt haplotypes at positions 72-76 in Plasmodium falciparum isolates collected from individuals in 2003 and 2012 in southeastern Cameroon was determined by sequence specific oligonucleotide probes-enzyme linked immunosorbent assay (SSOP-ELISA). The proportions of parasites carrying the mutant haplotype CVIET and the wild-type CVMNK were 53.0 and 28.0% in 2003, respectively. The proportion of the mutant haplotype in samples collected 9 years later decreased to 25.3% whereas the proportion of parasites carrying the wild-type CVMNK haplotype was 53.7%. Even though the proportion of chloroquine-sensitive parasites seems to be increasing in southeastern Cameroon, a reintroduction of chloroquine cannot be recommended at present in Cameroon. The current national anti-malarial drug policy should be implemented and reinforced to combat drug-resistant malaria.

The detection of pfcrt and pfmdr1 point mutations as molecular markers of chloroquine drug resistance, Pahang, Malaysia

PubMed Central

2012-01-01

Background Malaria is still a public health problem in Malaysia with chloroquine (CQ) being the first-line drug in the treatment policy of uncomplicated malaria. There is a scarcity in information about the magnitude of Plasmodium falciparum CQ resistance. This study aims to investigate the presence of single point mutations in the P. falciparum chloroquine-resistance transporter gene (pfcrt) at codons 76, 271, 326, 356 and 371 and in P. falciparum multi-drug resistance-1 gene (pfmdr1) at codons 86 and 1246, as molecular markers of CQ resistance. Methods A total of 75 P. falciparum blood samples were collected from different districts of Pahang state, Malaysia. Single nucleotide polymorphisms in pfcrt gene (codons 76, 271, 326, 356 and 371) and pfmdr1 gene (codons 86 and 1246) were analysed by using mutation-specific nested PCR and restriction fragment length polymorphism (PCR-RFLP) methods. Results Mutations of pfcrt K76T and pfcrt R371I were the most prevalent among pfcrt gene mutations reported by this study; 52% and 77%, respectively. Other codons of the pfcrt gene and the positions 86 and 1246 of the pfmdr1 gene were found mostly of wild type. Significant associations of pfcrt K76T, pfcrt N326S and pfcrt I356T mutations with parasitaemia were also reported. Conclusion The high existence of mutant pfcrt T76 may indicate the low susceptibility of P. falciparum isolates to CQ in Peninsular Malaysia. The findings of this study establish baseline data on the molecular markers of P. falciparum CQ resistance, which may help in the surveillance of drug resistance in Peninsular Malaysia. PMID:22853645

Evaluation of the rapid diagnostic test SDFK40 (Pf-pLDH/pan-pLDH) for the diagnosis of malaria in a non-endemic setting

PubMed Central

2011-01-01

Background The present study evaluated the SD Bioline Malaria Ag 05FK40 (SDFK40), a three-band RDT detecting Plasmodium falciparum-specific parasite lactate dehydrogenase (Pf-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH), in a reference setting. Methods The SDFK40 was retrospectively and prospectively tested against a panel of stored (n = 341) and fresh (n = 181) whole blood samples obtained in international travelers suspected of malaria, representing the four Plasmodium species as well as Plasmodium negative samples, and compared to microscopy and PCR results. The prospective panel was run together with OptiMAL (Pf-pLDH/pan-pLDH) and SDFK60 (histidine-rich protein-2 (HRP-2)/pan-pLDH). Results Overall sensitivities for P. falciparum tested retrospectively and prospectively were 67.9% and 78.8%, reaching 100% and 94.6% at parasite densities >1,000/μl. Sensitivity at parasite densities ≤ 100/μl was 9.1%. Overall sensitivities for Plasmodium vivax and Plasmodium ovale were 86.7% and 80.0% (retrospectively) and 92.9% and 76.9% (prospectively), reaching 94.7% for both species (retrospective panel) at parasite densities >500/μl. Sensitivity for Plasmodium malariae was 21.4%. Species mismatch occurred in 0.7% of samples (3/411) and was limited to non-falciparum species erroneously identified as P. falciparum. None of the Plasmodium negative samples in the retrospective panel reacted positive. Compared to OptiMAL and SDFK60, SDFK40 showed lower sensitivities for P. falciparum, but better detection of P. ovale. Inter-observer agreement and test reproducibility were excellent, but lot-to-lot variability was observed for pan-pLDH results in case of P. falciparum. Conclusion SDFK40 performance was poor at low (≤ 100/μl) parasite densities, precluding its use as the only diagnostic tool for malaria diagnosis. SDFK40 performed excellent for P. falciparum samples at high (>1,000/μl) parasite densities as well as for detection of P. vivax and P. ovale at parasite densities >500/μl. PMID:21226920

Evaluation of the rapid diagnostic test SDFK40 (Pf-pLDH/pan-pLDH) for the diagnosis of malaria in a non-endemic setting.

PubMed

Maltha, Jessica; Gillet, Philippe; Cnops, Lieselotte; Bottieau, Emmanuel; Van Esbroeck, Marjan; Bruggeman, Cathrien; Jacobs, Jan

2011-01-12

The present study evaluated the SD Bioline Malaria Ag 05FK40 (SDFK40), a three-band RDT detecting Plasmodium falciparum-specific parasite lactate dehydrogenase (Pf-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH), in a reference setting. The SDFK40 was retrospectively and prospectively tested against a panel of stored (n = 341) and fresh (n = 181) whole blood samples obtained in international travelers suspected of malaria, representing the four Plasmodium species as well as Plasmodium negative samples, and compared to microscopy and PCR results. The prospective panel was run together with OptiMAL (Pf-pLDH/pan-pLDH) and SDFK60 (histidine-rich protein-2 (HRP-2)/pan-pLDH). Overall sensitivities for P. falciparum tested retrospectively and prospectively were 67.9% and 78.8%, reaching 100% and 94.6% at parasite densities >1,000/μl. Sensitivity at parasite densities ≤ 100/μl was 9.1%. Overall sensitivities for Plasmodium vivax and Plasmodium ovale were 86.7% and 80.0% (retrospectively) and 92.9% and 76.9% (prospectively), reaching 94.7% for both species (retrospective panel) at parasite densities >500/μl. Sensitivity for Plasmodium malariae was 21.4%. Species mismatch occurred in 0.7% of samples (3/411) and was limited to non-falciparum species erroneously identified as P. falciparum. None of the Plasmodium negative samples in the retrospective panel reacted positive. Compared to OptiMAL and SDFK60, SDFK40 showed lower sensitivities for P. falciparum, but better detection of P. ovale. Inter-observer agreement and test reproducibility were excellent, but lot-to-lot variability was observed for pan-pLDH results in case of P. falciparum. SDFK40 performance was poor at low (≤ 100/μl) parasite densities, precluding its use as the only diagnostic tool for malaria diagnosis. SDFK40 performed excellent for P. falciparum samples at high (>1,000/μl) parasite densities as well as for detection of P. vivax and P. ovale at parasite densities >500/μl.

Evaluation of the Clearview® Malaria pLDH Malaria Rapid Diagnostic Test in a non-endemic setting.

PubMed

Houzé, Sandrine; Hubert, Véronique; Cohen, Dorit Pessler; Rivetz, Baruch; Le Bras, Jacques

2011-09-27

Malaria Rapid Diagnostic Tests (RDTs) are widely used to diagnose malaria. The present study evaluated a new RDT, the Clearview® Malaria pLDH test targeting the pan-Plasmodium antigen lactate dehydrogenase (pLDH). The Clearview® Malaria pLDH test was evaluated on fresh samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included samples were Plasmodium falciparum (139), Plasmodium vivax (22), Plasmodium ovale (20), Plasmodium malariae (7), and 102 negative. Overall sensitivity for the detection of Plasmodium spp was 93.2%. For P. falciparum, the sensitivity was 98.6%; for P. vivax, P. ovale and P. malariae, overall sensitivities were 90.9%, 60.0% and 85.7% respectively. For P. falciparum and for P. vivax, the sensitivities increased to 100% at parasite densities above 100/μl. The specificity was 100%. The test was easily to perform and the result was stable for at least 1 hour. The Clearview® Malaria pLDH was efficient for the diagnosis of malaria. The test was very sensitive for P. falciparum and P. vivax detection. The sensitivities for P. ovale and P. malariae were better than other RDTs.

Artemisinin-based combination therapy in the treatment of uncomplicated malaria: review of recent regulatory experience at the European Medicines Agency.

PubMed

Pelfrene, Eric; Pinheiro, Marie-Hélène; Cavaleri, Marco

2015-07-01

Malaria remains a major public health challenge with almost half of the world's population exposed to the risk of contracting the illness. Prompt, effective and well tolerated treatment remains one of the cornerstones in the disease management, with artemisinin-based combination therapy the recommended option for non-severe malaria in endemic areas with predominant Plasmodium falciparum infections.Recent experience has been obtained at the European Medicines Agency with regulatory approval of two such antimalarial fixed combination products. For these cases, two different regulatory pathways were applied. As such, the present contribution describes this experience, emphasising main differences and applicability offered by these regulatory choices. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.

Clinical diagnosis of uncomplicated malaria in Sri Lanka.

PubMed

van der Hoek, W; Premasiri, D A; Wickremasinghe, A R

1998-06-01

To assess the possibility of developing a protocol for the clinical diagnosis of malaria, a study was done at the regional laboratory of the Anti-Malaria Campaign in Puttalam, Sri Lanka. Of a group of 502 patients, who suspected they were suffering from malaria, 97 had a positive blood film for malaria parasites (71 Plasmodium vivax and 26 P. falciparum). There were no important differences in signs and symptoms between those with positive and those with negative blood films. It is argued that it is unlikely that health workers can improve on the diagnosis of malaria made by the patients themselves, if laboratory facilities are not available. For Sri Lanka the best option is to expand the number of facilities where microscopic examination for malaria parasites can take place.

Treatment of Chronic Asymptomatic Plasmodium falciparum Infection Does Not Increase the Risk of Clinical Malaria Upon Reinfection.

PubMed

Portugal, Silvia; Tran, Tuan M; Ongoiba, Aissata; Bathily, Aboudramane; Li, Shanping; Doumbo, Safiatou; Skinner, Jeff; Doumtabe, Didier; Kone, Younoussou; Sangala, Jules; Jain, Aarti; Davies, D Huw; Hung, Christopher; Liang, Li; Ricklefs, Stacy; Homann, Manijeh Vafa; Felgner, Philip L; Porcella, Stephen F; Färnert, Anna; Doumbo, Ogobara K; Kayentao, Kassoum; Greenwood, Brian M; Traore, Boubacar; Crompton, Peter D

2017-03-01

Chronic asymptomatic Plasmodium falciparum infections are common in endemic areas and are thought to contribute to the maintenance of malaria immunity. Whether treatment of these infections increases the subsequent risk of clinical episodes of malaria is unclear. In a 3-year study in Mali, asymptomatic individuals with or without P. falciparum infection at the end of the 6-month dry season were identified by polymerase chain reaction (PCR), and clinical malaria risk was compared during the ensuing 6-month malaria transmission season. At the end of the second dry season, 3 groups of asymptomatic children were identified: (1) children infected with P. falciparum as detected by rapid diagnostic testing (RDT) who were treated with antimalarials (n = 104), (2) RDT-negative children whose untreated P. falciparum infections were detected retrospectively by PCR (n = 55), and (3) uninfected children (RDT/PCR negative) (n = 434). Clinical malaria risk during 2 subsequent malaria seasons was compared. Plasmodium falciparum-specific antibody kinetics during the dry season were compared in children who did or did not harbor asymptomatic P. falciparum infections. Chronic asymptomatic P. falciparum infection predicted decreased clinical malaria risk during the subsequent malaria season(s); treatment of these infections did not alter this reduced risk. Plasmodium falciparum-specific antibodies declined similarly in children who did or did not harbor chronic asymptomatic P. falciparum infection during the dry season. These findings challenge the notion that chronic asymptomatic P. falciparum infection maintains malaria immunity and suggest that mass drug administration during the dry season should not increase the subsequent risk of clinical malaria. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Prevalence of PCR detectable malaria infection among febrile patients with a negative Plasmodium falciparum specific rapid diagnostic test in Zanzibar.

PubMed

Baltzell, Kimberly A; Shakely, Deler; Hsiang, Michelle; Kemere, Jordan; Ali, Abdullah Suleiman; Björkman, Anders; Mårtensson, Andreas; Omar, Rahila; Elfving, Kristina; Msellem, Mwinyi; Aydin-Schmidt, Berit; Rosenthal, Philip J; Greenhouse, Bryan

2013-02-01

We screened for malaria in 594 blood samples from febrile patients who tested negative by a Plasmodium falciparum-specific histidine-rich protein-2-based rapid diagnostic test at 12 health facilities in Zanzibar districts North A and Micheweni, from May to August 2010. Screening was with microscopy, polymerase chain reaction (PCR) targeting the cytochrome b gene (cytbPCR) of the four major human malaria species, and quantitative PCR (qPCR). The prevalence of cytbPCR-detectable malaria infection was 2% (12 of 594), including 8 P. falciparum, 3 Plasmodium malariae, and 1 Plasmodium vivax infections. Microscopy identified 4 of 8 P. falciparum infections. Parasite density as estimated by microscopy or qPCR was > 4,000 parasites/μL in 5 of 8 cytbPCR-detectable P. falciparum infections. The infections that were missed by the rapid diagnostic test represent a particular challenge in malaria elimination settings and highlight the need for more sensitive point-of-care diagnostic tools to improve case detection of all human malaria species in febrile patients.

Evaluation of CareStart™ malaria Pf/Pv combo test for Plasmodium falciparum and Plasmodium vivax malaria diagnosis in Butajira area, south-central Ethiopia.

PubMed

Woyessa, Adugna; Deressa, Wakgari; Ali, Ahmed; Lindtjørn, Bernt

2013-06-27

Malaria is a major public health problem in Ethiopia. Plasmodium falciparum and Plasmodium vivax co-exist and malaria rapid diagnostic test (RDTs) is vital in rendering parasite-confirmed treatment especially in areas where microscopy from 2008 to 2010 is not available. CareStartTM Malaria Pf/Pv combo test was evaluated compared to microscopy in Butajira area, south-central Ethiopia. This RDT detects histidine-rich protein-2 (HRP2) found in P. falciparum, and Plasmodium enzyme lactate dehydrogenase (pLDH) for diagnosis of P. vivax. The standard for the reporting of diagnostic accuracy studies was complied. Among 2,394 participants enrolled, 10.9% (n=87) were Plasmodium infected (household survey) and 24.5% (n=392) health facility-based using microscopy. In the household surveys, the highest positivity was caused by P. vivax (83.9%, n=73), P. falciparum (15.0%, n=13), and the rest due to mixed infections of both (1.1%, n=1). In health facility, P. vivax caused 78.6% (n=308), P. falciparum caused 20.4% (n=80), and the rest caused by mixed infections 1.0% (n=4). RDT missed 9.1% (n=8) in household and 4.3% (n=17) in health facility-based surveys among Plasmodium positive confirmed by microscopy while 3.3% (n=24) in household and 17.2% (n=208) in health facility-based surveys were detected false positive. RDT showed agreement with microscopy in detecting 79 positives in household surveys (n=796) and 375 positives in health centre survey (n=1,598).RDT performance varied in both survey settings, lowest PPV (64.3%) for Plasmodium and P. falciparum (77.2%) in health centres; and Plasmodium (76.7%) and P. falciparum (87.5%) in household surveys. NPV was low in P. vivax in health centres (77.2%) and household (87.5%) surveys. Seasonally varying RDT precision of as low as 14.3% PPV (Dec. 2009), and 38.5% NPV (Nov. 2008) in health centre surveys; and 40-63.6% PPV was observed in household surveys. But the influence of age and parasite density on RDT performance was not ascertained. Establishing quality control of malaria RDT in the health system in areas with low endemic and where P. falciparum and P. vivax co-exist is recommendable. CareStartTM RDT might be employed for epidemiological studies that require interpreting the results cautiously. Future RDT field evaluation against microscopy should be PCR corrected.

Amplification of a Gene Related to Mammalian mdr Genes in Drug-Resistant Plasmodium falciparum

NASA Astrophysics Data System (ADS)

Wilson, Craig M.; Serrano, Adelfa E.; Wasley, Annemarie; Bogenschutz, Michael P.; Shankar, Anuraj H.; Wirth, Dyann F.

1989-06-01

The malaria parasite Plasmodium falciparum contains at least two genes related to the mammalian multiple drug resistance genes, and at least one of the P. falciparum genes is expressed at a higher level and is present in higher copy number in a strain that is resistant to multiple drugs than in a strain that is sensitive to the drugs.

Plasmodium falciparum: a simplified technique for obtaining singly infected erythrocytes.

PubMed

Puthia, Manoj K; Tan, Kevin S W

2005-02-01

We report the development of a simple technique involving 15 ml polypropylene tubes and a rotatory incubator for obtaining erythrocytes singly infected with Plasmodium falciparum. This technique will be useful for cloning of the parasite. Our finding that P. falciparum merozoite invasion is inhibited during rotation suggests that this method may also be useful for the study of parasite-erythrocyte interactions under dynamic circulatory conditions.

Probable chloroquine-resistant Plasmodium falciparum malaria from Mozambique A case report.

PubMed

Pillay, N; Bhoola, R L

1975-08-16

A female patient with Plasmodium falciparum malaria apparently resistant to chloroquine is descirbed. She had recently returned from Mozambique, which may prove to be a new endemic are with resistant strains. The infection was successfully treated with quinine.

Randomized Controlled Trial of Levamisole Hydrochloride as Adjunctive Therapy in Severe Falciparum Malaria With High Parasitemia

PubMed Central

Maude, Richard J.; Silamut, Kamolrat; Plewes, Katherine; Charunwatthana, Prakaykaew; Ho, May; Abul Faiz, M.; Rahman, Ridwanur; Hossain, Md Amir; Hassan, Mahtab U.; Bin Yunus, Emran; Hoque, Gofranul; Islam, Faridul; Ghose, Aniruddha; Hanson, Josh; Schlatter, Joel; Lacey, Rachel; Eastaugh, Alison; Tarning, Joel; Lee, Sue J.; White, Nicholas J.; Chotivanich, Kesinee; Day, Nicholas P. J.; Dondorp, Arjen M.

2014-01-01

Background. Cytoadherence and sequestration of erythrocytes containing mature stages of Plasmodium falciparum are central to the pathogenesis of severe malaria. The oral anthelminthic drug levamisole inhibits cytoadherence in vitro and reduces sequestration of late-stage parasites in uncomplicated falciparum malaria treated with quinine. Methods. Fifty-six adult patients with severe malaria and high parasitemia admitted to a referral hospital in Bangladesh were randomized to receive a single dose of levamisole hydrochloride (150 mg) or no adjuvant to antimalarial treatment with intravenous artesunate. Results. Circulating late-stage parasites measured as the median area under the parasite clearance curves were 2150 (interquartile range [IQR], 0–28 025) parasites/µL × hour in patients treated with levamisole and 5489 (IQR, 192–25 848) parasites/µL × hour in controls (P = .25). The “sequestration ratios” at 6 and 12 hours for all parasite stages and changes in microvascular blood flow did not differ between treatment groups (all P > .40). The median time to normalization of plasma lactate (<2 mmol/L) was 24 (IQR, 12–30) hours with levamisole vs 28 (IQR, 12–36) hours without levamisole (P = .15). Conclusions. There was no benefit of a single-dose of levamisole hydrochloride as adjuvant to intravenous artesunate in the treatment of adults with severe falciparum malaria. Rapid parasite killing by intravenous artesunate might obscure the effects of levamisole. PMID:23943850

Refrigeration provides a simple means to synchronize in vitro cultures of Plasmodium falciparum

PubMed Central

Yuan, Lili; Hao, Mingming; Wu, Lanou; Zhao, Zhen; Rosenthal, Benjamin M.; Li, Xiaomei; He, Yongshu; Sun, Ling; Feng, Guohua; Xiang, Zheng; Cui, Liwang; Yang, Zhaoqing

2014-01-01

Plasmodium falciparum is usually asynchronous during in vitro culture. Highly synchronized cultures of Plasmodium falciparum are routinely used in malaria research. Here, we describe a simple synchronization procedure for P. falciparum asexual erythrocytic culture, which involves storage at 4°C for 8–24 h followed by routine culture. When cultures with 27–60% of ring stage were synchronized using this procedure, 70–93% ring stages were obtained after 48 h of culture and relative growth synchrony remained for at least two erythrocytic cycles. To test the suitability of this procedure for subsequent work, drug sensitivity assays were performed using four laboratory strains and four freshly adapted clinical P. falciparum isolates. Parasites synchronized by sorbitol treatment or refrigeration showed similar dose-response curves and comparable IC50 values to four antimalarial drugs. The refrigeration synchronization method is simple, inexpensive, time-saving, and should be especially useful when large numbers of P. falciparum culture are handled. PMID:24632190

The weekly associations between climatic factors and Plasmodium vivax and Plasmodium falciparum malaria in China, 2005-2014.

PubMed

Hundessa, Samuel; Williams, Gail; Li, Shanshan; Guo, Jinpeng; Zhang, Wenyi; Guo, Yuming

2017-05-01

Meteorological factors play a crucial role in malaria transmission, but limited evidence is available from China. This study aimed to estimate the weekly associations between meteorological factors and Plasmodium vivax and Plasmodium falciparum malaria in China. The Distributed Lag Non-Linear Model was used to examine non-linearity and delayed effects of average temperature, rainfall, relative humidity, sunshine hours, wind speed and atmospheric pressure on malaria. Average temperature was associated with P. vivax and P. falciparum cases over long ranges of lags. The effect was more immediate on P. vivax (0-6 weeks) than on P. falciparum (1-9 weeks). Relative humidity was associated with P. vivax and P. falciparum over 8-10 weeks and 5-8 weeks lag, respectively. A significant effect of wind speed on P. vivax was observed at 0-2 weeks lag, but no association was found with P. falciparum. Rainfall had a decreasing effect on P. vivax, but no association was found with P. falciparum. Sunshine hours were negatively associated with P. falciparum, but the association was unclear for P. vixax. However, the effects of atmospheric pressure on both malaria types were not significant at any lag. Our study highlights a substantial effect of weekly climatic factors on P. vivax and P. falciparum malaria transmission in China, with different lags. This provides an evidence base for health authorities in developing a malaria early-warning system. © The Author 2017. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Unusual Transmission of Plasmodium falciparum, Bordeaux, France, 2009

PubMed Central

Vareil, Marc-Olivier; Tandonnet, Olivier; Chemoul, Audrey; Bogreau, Hervé; Saint-Léger, Mélanie; Micheau, Maguy; Millet, Pascal; Koeck, Jean-Louis; Boyer, Alexandre; Rogier, Christophe

2011-01-01

Plasmodium falciparum malaria is usually transmitted by mosquitoes. We report 2 cases in France transmitted by other modes: occupational blood exposure and blood transfusion. Even where malaria is not endemic, it should be considered as a cause of unexplained acute fever. PMID:21291597

[Construction of Plasmodium falciparum signal peptide peptidase-GFP mutant and its expression analysis in the malaria parasite].

PubMed

Li, Xue-rong; Wu, Yin-juan; Shang, Mei; Li, Ye; Xu, Jin; Yu, Xin-bing; Athar, Chishti

2014-08-01

To construct recombinant plasmid pSPPcGT which contains signal peptide peptidase gene of Plasmodium falciparum (PJSPP) and GFP, and transfect into P. falciparum (3D7 strain) to obtain mutant parasites which can express PJSPP-GFP. Plasmodium falciparum(3D7 strain) genomic DNA was extracted from cultured malaria parasites. The C-terminal region of PJSPP, an 883 bp gene fragment was amplified by PCR, and then cloned into pPM2GT vector to get recombinant vector pSPPcGT. The recombinant vectors were identified by PCR, double restriction enzyme digestion and DNA sequencing. pSPPcGT vector was transfected into malaria parasites. The positive clones were selected by adding inhibitor of Plasmodium falciparum dihydrofolate reductase WR99210 to the culture medium. The pSPP-GFP-transfected parasites were fixed with methanol, stained with DAPI, and observed under immunofluorescence microscope. The PJSPP-GFP expression in P. falciparum was identified by SDS-PAGE and Western blotting. The C-terminal region of PJSPP was amplified from P.falciparum (3D7 strain) genomic DNA by PCR with the length of 883 bp. The constructed recombinant vectors were identified by PCR screening, double restriction enzyme digestion and DNA sequencing. The pSPPcGT vector was transfected into P. falciparum and the positive clones were selected by WR99210. GFP fluorescence was observed in transfected parasites by immunofluorescence microscopy, and mainly located in the cytoplasm. The PJSPP-GFP expression in malaria parasites was confirmed by Western blotting with a relative molecular mass of Mr 64,000. Recombinant vector PJSPP-GFP is constructed and transfected into P. falciparum to obtain P. falciparum mutant clone which can express PfSPP-GFP.

DNA secondary structures are associated with recombination in major Plasmodium falciparum variable surface antigen gene families

PubMed Central

Sander, Adam F.; Lavstsen, Thomas; Rask, Thomas S.; Lisby, Michael; Salanti, Ali; Fordyce, Sarah L.; Jespersen, Jakob S.; Carter, Richard; Deitsch, Kirk W.; Theander, Thor G.; Pedersen, Anders Gorm; Arnot, David E.

2014-01-01

Many bacterial, viral and parasitic pathogens undergo antigenic variation to counter host immune defense mechanisms. In Plasmodium falciparum, the most lethal of human malaria parasites, switching of var gene expression results in alternating expression of the adhesion proteins of the Plasmodium falciparum-erythrocyte membrane protein 1 class on the infected erythrocyte surface. Recombination clearly generates var diversity, but the nature and control of the genetic exchanges involved remain unclear. By experimental and bioinformatic identification of recombination events and genome-wide recombination hotspots in var genes, we show that during the parasite’s sexual stages, ectopic recombination between isogenous var paralogs occurs near low folding free energy DNA 50-mers and that these sequences are heavily concentrated at the boundaries of regions encoding individual Plasmodium falciparum-erythrocyte membrane protein 1 structural domains. The recombinogenic potential of these 50-mers is not parasite-specific because these sequences also induce recombination when transferred to the yeast Saccharomyces cerevisiae. Genetic cross data suggest that DNA secondary structures (DSS) act as inducers of recombination during DNA replication in P. falciparum sexual stages, and that these DSS-regulated genetic exchanges generate functional and diverse P. falciparum adhesion antigens. DSS-induced recombination may represent a common mechanism for optimizing the evolvability of virulence gene families in pathogens. PMID:24253306

Higher microsatellite diversity in Plasmodium vivax than in sympatric Plasmodium falciparum populations in Pursat, Western Cambodia.

PubMed

Orjuela-Sánchez, Pamela; Sá, Juliana M; Brandi, Michelle C C; Rodrigues, Priscila T; Bastos, Melissa S; Amaratunga, Chanaki; Duong, Socheat; Fairhurst, Rick M; Ferreira, Marcelo U

2013-07-01

Previous microsatellite analyses of sympatric populations of Plasmodium vivax and Plasmodium falciparum in Brazil revealed higher diversity in the former species. However, it remains unclear whether regional species-specific differences in prevalence and transmission levels might account for these findings. Here, we examine sympatric populations of P. vivax (n=87) and P. falciparum (n=164) parasites from Pursat province, Western Cambodia, where both species are similarly prevalent. Using 10 genome-wide microsatellites for P. falciparum and 13 for P. vivax, we found that the P. vivax population was more diverse than the sympatric P. falciparum population (average virtual heterozygosity [HE], 0.87 vs. 0.66, P=0.003), with more multiple-clone infections (89.6% vs. 47.6%) and larger mean number of alleles per marker (16.2 vs. 11.1, P=0.07). Both populations showed significant multi-locus linkage disequilibrium suggestive of a predominantly clonal mode of parasite reproduction. The higher microsatellite diversity found in P. vivax isolates, compared to sympatric P. falciparum isolates, does not necessarily result from local differences in transmission level and may reflect differences in population history between species or increased mutation rates in P. vivax. Copyright © 2013 Elsevier Inc. All rights reserved.

Artemisinin-Naphthoquine versus Artemether-Lumefantrine for Uncomplicated Malaria in Papua New Guinean Children: An Open-Label Randomized Trial

PubMed Central

Laman, Moses; Moore, Brioni R.; Benjamin, John M.; Yadi, Gumul; Bona, Cathy; Warrel, Jonathan; Kattenberg, Johanna H.; Koleala, Tamarah; Manning, Laurens; Kasian, Bernadine; Robinson, Leanne J.; Sambale, Naomi; Lorry, Lina; Karl, Stephan; Davis, Wendy A.; Rosanas-Urgell, Anna; Mueller, Ivo; Siba, Peter M.; Betuela, Inoni; Davis, Timothy M. E.

2014-01-01

Background Artemisinin combination therapies (ACTs) with broad efficacy are needed where multiple Plasmodium species are transmitted, especially in children, who bear the brunt of infection in endemic areas. In Papua New Guinea (PNG), artemether-lumefantrine is the first-line treatment for uncomplicated malaria, but it has limited efficacy against P. vivax. Artemisinin-naphthoquine should have greater activity in vivax malaria because the elimination of naphthoquine is slower than that of lumefantrine. In this study, the efficacy, tolerability, and safety of these ACTs were assessed in PNG children aged 0.5–5 y. Methods and Findings An open-label, randomized, parallel-group trial of artemether-lumefantrine (six doses over 3 d) and artemisinin-naphthoquine (three daily doses) was conducted between 28 March 2011 and 22 April 2013. Parasitologic outcomes were assessed without knowledge of treatment allocation. Primary endpoints were the 42-d P. falciparum PCR-corrected adequate clinical and parasitologic response (ACPR) and the P. vivax PCR-uncorrected 42-d ACPR. Non-inferiority and superiority designs were used for falciparum and vivax malaria, respectively. Because the artemisinin-naphthoquine regimen involved three doses rather than the manufacturer-specified single dose, the first 188 children underwent detailed safety monitoring. Of 2,542 febrile children screened, 267 were randomized, and 186 with falciparum and 47 with vivax malaria completed the 42-d follow-up. Both ACTs were safe and well tolerated. P. falciparum ACPRs were 97.8% and 100.0% in artemether-lumefantrine and artemisinin-naphthoquine-treated patients, respectively (difference 2.2% [95% CI −3.0% to 8.4%] versus −5.0% non-inferiority margin, p = 0.24), and P. vivax ACPRs were 30.0% and 100.0%, respectively (difference 70.0% [95% CI 40.9%–87.2%], p<0.001). Limitations included the exclusion of 11% of randomized patients with sub-threshold parasitemias on confirmatory microscopy and direct observation of only morning artemether-lumefantrine dosing. Conclusions Artemisinin-naphthoquine is non-inferior to artemether-lumefantrine in PNG children with falciparum malaria but has greater efficacy against vivax malaria, findings with implications in similar geo-epidemiologic settings within and beyond Oceania. Trial registration Australian New Zealand Clinical Trials Registry ACTRN12610000913077 Please see later in the article for the Editors' Summary PMID:25549086

Potentiation of Artemisinin Activity against Chloroquine-Resistant Plasmodium falciparum Strains by Using Heme Models

PubMed Central

Benoit-Vical, Françoise; Robert, Anne; Meunier, Bernard

1999-01-01

The influence of different metalloporphyrin derivatives on the antimalarial activity of artemisinin was studied with two chloroquine-resistant strains of Plasmodium falciparum (FcB1-Colombia and FcM29-Cameroon) cultured in human erythrocytes. This potentiation study indicates that the manganese complex of meso-tetrakis(4-sulfonatophenyl)porphyrin has a significant synergistic effect on the activity of artemisinin against both Plasmodium strains. PMID:10508044

Phylogenomic analyses of malaria parasites and evolution of their exported proteins

PubMed Central

2011-01-01

Background Plasmodium falciparum is the most malignant agent of human malaria. It belongs to the taxon Laverania, which includes other ape-infecting Plasmodium species. The origin of the Laverania is still debated. P. falciparum exports pathogenicity-related proteins into the host cell using the Plasmodium export element (PEXEL). Predictions based on the presence of a PEXEL motif suggest that more than 300 proteins are exported by P. falciparum, while there are many fewer exported proteins in non-Laverania. Results A whole-genome approach was applied to resolve the phylogeny of eight Plasmodium species and four outgroup taxa. By using 218 orthologous proteins we received unanimous support for a sister group position of Laverania and avian malaria parasites. This observation was corroborated by the analyses of 28 exported proteins with orthologs present in all Plasmodium species. Most interestingly, several deviations from the P. falciparum PEXEL motif were found to be present in the orthologous sequences of non-Laverania. Conclusion Our phylogenomic analyses strongly support the hypotheses that the Laverania have been founded by a single Plasmodium species switching from birds to African great apes or vice versa. The deviations from the canonical PEXEL motif in orthologs may explain the comparably low number of exported proteins that have been predicted in non-Laverania. PMID:21676252

Evaluation of the Clearview® malaria pLDH malaria rapid diagnostic test in a non-endemic setting

PubMed Central

2011-01-01

Background Malaria Rapid Diagnostic Tests (RDTs) are widely used to diagnose malaria. The present study evaluated a new RDT, the Clearview® Malaria pLDH test targeting the pan-Plasmodium antigen lactate dehydrogenase (pLDH). Methods The Clearview® Malaria pLDH test was evaluated on fresh samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included samples were Plasmodium falciparum (139), Plasmodium vivax (22), Plasmodium ovale (20), Plasmodium malariae (7), and 102 negative. Results Overall sensitivity for the detection of Plasmodium spp was 93.2%. For P. falciparum, the sensitivity was 98.6%; for P. vivax, P. ovale and P. malariae, overall sensitivities were 90.9%, 60.0% and 85.7% respectively. For P. falciparum and for P. vivax, the sensitivities increased to 100% at parasite densities above 100/μl. The specificity was 100%. The test was easily to perform and the result was stable for at least 1 hour. Conclusion The Clearview® Malaria pLDH was efficient for the diagnosis of malaria. The test was very sensitive for P. falciparum and P. vivax detection. The sensitivities for P. ovale and P. malariae were better than other RDTs PMID:21951996

Decreasing pfmdr1 Copy Number Suggests that Plasmodium falciparum in Western Cambodia Is Regaining In Vitro Susceptibility to Mefloquine

PubMed Central

Lim, Pharath; Dek, Dalin; Try, Vorleak; Sreng, Sokunthea; Suon, Seila

2015-01-01

Dihydroartemisinin-piperaquine is the current frontline artemisinin combination therapy (ACT) for Plasmodium falciparum malaria in Cambodia but is now failing in several western provinces. To investigate artesunate plus mefloquine (AS+MQ) as a replacement ACT, we measured the prevalence of multiple pfmdr1 copies—a molecular marker for MQ resistance—in 844 P. falciparum clinical isolates collected in 2008 to 2013. The pfmdr1 copy number is decreasing in Western Cambodia, suggesting that P. falciparum is regaining in vitro susceptibility to MQ. PMID:25712365

Study protocol for a randomised controlled double-blinded trial of the dose-dependent efficacy and safety of primaquine for clearance of gametocytes in children with uncomplicated falciparum malaria in Uganda.

PubMed

Eziefula, Alice Chijioke; Staedke, Sarah G; Yeung, Shunmay; Webb, Emily; Kamya, Moses; White, Nicholas J; Bousema, Teun; Drakeley, Chris

2013-03-26

For the purpose of blocking transmission of Plasmodium falciparum malaria from humans to mosquitoes, a single dose of primaquine is recommended by the WHO as an addition to artemisinin combination therapy. Primaquine clears gametocytes but causes dose-dependent haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Evidence is needed to inform the optimal dosing of primaquine for malaria elimination programmes and for the purpose of interrupting the spread of artemisinin-resistant malaria. This study investigates the efficacy and safety of reducing doses of primaquine for clearance of gametocytes in participants with normal G6PD status. In this prospective, four-armed randomised placebo-controlled double-blinded trial, children aged 1-10 years, weighing over 10 kg, with haemoglobin ≥8 g/dl and uncomplicated P falciparum malaria are treated with artemether lumefantrine and randomised to receive a dose of primaquine (0.1, 0.4 or 0.75 mg base/kg) or placebo on the third day of treatment. Participants are followed up for 28 days. Gametocytaemia is measured by quantitative nucleic acid sequence-based analysis on days 0, 2, 3, 7, 10 and 14 with a primary endpoint of the number of days to gametocyte clearance in each treatment arm and secondarily the area under the curve of gametocyte density over time. Analysis is for non-inferiority of efficacy compared to the reference dose, 0.75 mg base/kg. Safety is assessed by pair-wise comparisons of the arithmetic mean (±SD) change in haemoglobin concentration per treatment arm and analysed for superiority to placebo and incidence of adverse events. Ethics and dissemination Approval was obtained from the ethical committees of Makerere University School of Medicine, the Ugandan National Council of Science and Technology and the London School of Hygiene and Tropical Medicine. These will be disseminated to inform malaria elimination policy, through peer-reviewed publication and academic presentations.

The use of Aotus Trivirgatus and Macaca Mulatta as Tools for Studies on Prevention and Therapy of Infections with Plasmodium Falciparum and Plasmodium Vivax

DTIC Science & Technology

1976-08-13

INFECTIONS WITH PLASMODIUM FALCIPARUM AND PLASMODIUM VIVAX (U) FINAL PROGRESS REPORT ( PROJECT 2284-XXIX) For the Period I May 1975 to 30 April...IT» IOC mit settiM I’jtf Section ^ I» ’■■■■• BisTtmunM/MWUiiun cooa DiJÜ iWBU. UK/» FINAL PROGRESS REPORT ( PROJECT 2284-XXIX) S...quinolinemethanols pyridinemethanols I ’As in previous years, the activities of this Project were focused on development of: (a) agents fully effective

Plasmodium falciparum Serine/Threonine Phosphoprotein Phosphatases (PPP): From Housekeeper to 'Holy Grail'

USDA-ARS?s Scientific Manuscript database

Availability of complete genome sequence for Plasmodium falciparum has been useful in drawing a comprehensive metabolic map of the parasite. Distinct and unique metabolic characteristics of the parasite may be exploited as potential targets for new antimalarial drug discovery research. Reversible ph...

Asymptomatic infection in individuals from the municipality of Barcelos (Brazilian Amazon) is not associated with the anti-Plasmodium falciparum glycosylphosphatidylinositol antibody response

PubMed Central

Gomes, Larissa Rodrigues; Totino, Paulo Renato Rivas; Sanchez, Maria Carmen Arroyo; Daniel, Elsa Paula da Silva Kaingona; de Macedo, Cristiana Santos; Fortes, Filomeno; Coura, José Rodrigues; Santi, Silvia Maria Di; Werneck, Guilherme Loureiro; Suárez-Mutis, Martha Cecilia; Ferreira-da-Cruz, Maria de Fátima; Daniel-Ribeiro, Cláudio Tadeu

2013-01-01

Anti-glycosylphosphatidylinositol (GPI) antibodies (Abs) may reflect and mediate, at least partially, anti-disease immunity in malaria by neutralising the toxic effect of parasitic GPI. Thus, we assessed the anti-GPI Ab response in asymptomatic individuals living in an area of the Brazilian Amazon that has a high level of malaria transmission. For comparative purposes, we also investigated the Ab response to a crude extract prepared from Plasmodium falciparum, the merozoite surface protein (MSP)3 antigen of P. falciparum and the MSP 1 antigen of Plasmodium vivax (PvMSP1-19) in these individuals and in Angolan patients with acute malaria. Our data suggest that the Ab response against P. falciparum GPI is not associated with P. falciparum asymptomatic infection in individuals who have been chronically exposed to malaria in the Brazilian Amazon. However, this Ab response could be related to ongoing parasitaemia (as was previously shown) in the Angolan patients. In addition, our data show that PvMSP1-19may be a good marker antigen to reflect previous exposure to Plasmodium in areas that have a high transmission rate of P. vivax. PMID:24037204

Performance of Rapid Diagnostic Tests for Imported Malaria in Clinical Practice: Results of a National Multicenter Study

PubMed Central

Houzé, Sandrine; Boutron, Isabelle; Marmorat, Anne; Dalichampt, Marie; Choquet, Christophe; Poilane, Isabelle; Godineau, Nadine; Le Guern, Anne-Sophie; Thellier, Marc; Broutier, Hélène; Fenneteau, Odile; Millet, Pascal; Dulucq, Stéphanie; Hubert, Véronique; Houzé, Pascal; Tubach, Florence; Le Bras, Jacques; Matheron, Sophie

2013-01-01

We compared the performance of four rapid diagnostic tests (RDTs) for imported malaria, and particularly Plasmodium falciparum infection, using thick and thin blood smears as the gold standard. All the tests are designed to detect at least one protein specific to P. falciparum ( Plasmodium histidine-rich protein 2 (PfHRP2) or Plasmodium LDH (PfLDH)) and one pan-Plasmodium protein (aldolase or Plasmodium LDH (pLDH)). 1,311 consecutive patients presenting to 9 French hospitals with suspected malaria were included in this prospective study between April 2006 and September 2008. Blood smears revealed malaria parasites in 374 cases (29%). For the diagnosis of P. falciparum infection, the three tests detecting PfHRP2 showed high and similar sensitivity (96%), positive predictive value (PPV) (90%) and negative predictive value (NPV) (98%). The PfLDH test showed lower sensitivity (83%) and NPV (80%), despite good PPV (98%). For the diagnosis of non-falciparum species, the PPV and NPV of tests targeting pLDH or aldolase were 94–99% and 52–64%, respectively. PfHRP2-based RDTs are thus an acceptable alternative to routine microscopy for diagnosing P. falciparum malaria. However, as malaria may be misdiagnosed with RDTs, all negative results must be confirmed by the reference diagnostic method when clinical, biological or other factors are highly suggestive of malaria. PMID:24098699

Changing epidemiology of malaria in Sabah, Malaysia: increasing incidence of Plasmodium knowlesi.

PubMed

William, Timothy; Jelip, Jenarun; Menon, Jayaram; Anderios, Fread; Mohammad, Rashidah; Awang Mohammad, Tajul A; Grigg, Matthew J; Yeo, Tsin W; Anstey, Nicholas M; Barber, Bridget E

2014-10-02

While Malaysia has had great success in controlling Plasmodium falciparum and Plasmodium vivax, notifications of Plasmodium malariae and the microscopically near-identical Plasmodium knowlesi increased substantially over the past decade. However, whether this represents microscopic misdiagnosis or increased recognition of P. knowlesi has remained uncertain. To describe the changing epidemiology of malaria in Sabah, in particular the increasing incidence of P. knowlesi, a retrospective descriptive study was undertaken involving a review of Department of Health malaria notification data from 2012-2013, extending a previous review of these data from 1992-2011. In addition, malaria PCR and microscopy data from the State Public Health Laboratory were reviewed to estimate the accuracy of the microscopy-based notification data. Notifications of P. malariae/P. knowlesi increased from 703 in 2011 to 815 in 2012 and 996 in 2013. Notifications of P. vivax and P. falciparum decreased from 605 and 628, respectively, in 2011, to 297 and 263 in 2013. In 2013, P. malariae/P. knowlesi accounted for 62% of all malaria notifications compared to 35% in 2011. Among 1,082 P. malariae/P. knowlesi blood slides referred for PCR testing during 2011-2013, there were 924 (85%) P. knowlesi mono-infections, 30 (2.8%) P. falciparum, 43 (4.0%) P. vivax, seven (0.6%) P. malariae, six (0.6%) mixed infections, 31 (2.9%) positive only for Plasmodium genus, and 41 (3.8%) Plasmodium-negative. Plasmodium knowlesi mono-infection accounted for 32/156 (21%) and 33/87 (38%) blood slides diagnosed by microscopy as P. falciparum and P. vivax, respectively. Twenty-six malaria deaths were reported during 2010-2013, including 12 with 'P. malariae/P. knowlesi' (all adults), 12 with P. falciparum (seven adults), and two adults with P. vivax. Notifications of P. malariae/P. knowlesi in Sabah are increasing, with this trend likely reflecting a true increase in incidence of P. knowlesi and presenting a major threat to malaria control and elimination in Malaysia. With the decline of P. falciparum and P. vivax, control programmes need to incorporate measures to protect against P. knowlesi, with further research required to determine effective interventions.

Artesunate plus pyronaridine for treating uncomplicated Plasmodium falciparum malaria.

PubMed

Bukirwa, Hasifa; Unnikrishnan, B; Kramer, Christine V; Sinclair, David; Nair, Suma; Tharyan, Prathap

2014-03-04

The World Health Organization (WHO) recommends that people with uncomplicated Plasmodium falciparum malaria are treated using Artemisinin-based Combination Therapy (ACT). ACT combines three-days of a short-acting artemisinin derivative with a longer-acting antimalarial which has a different mode of action. Pyronaridine has been reported as an effective antimalarial over two decades of use in parts of Asia, and is currently being evaluated as a partner drug for artesunate. To evaluate the efficacy and safety of artesunate-pyronaridine compared to alternative ACTs for treating people with uncomplicated P. falciparum malaria. We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL), published in The Cochrane Library; MEDLINE; EMBASE; LILACS; ClinicalTrials.gov; the metaRegister of Controlled Trials (mRCT); and the WHO International Clinical Trials Search Portal up to 16 January 2014. We searched reference lists and conference abstracts, and contacted experts for information about ongoing and unpublished trials. Randomized controlled trials of artesunate-pyronaridine versus other ACTs in adults and children with uncomplicated P. falciparum malaria.For the safety analysis, we also included adverse events data from trials comparing any treatment regimen containing pyronaridine with regimens not containing pyronaridine. Two authors independently assessed trial eligibility and risk of bias, and extracted data. We combined dichotomous data using risk ratios (RR) and continuous data using mean differences (MD), and presented all results with a 95% confidence interval (CI). We used the GRADE approach to assess the quality of evidence. We included six randomized controlled trials enrolling 3718 children and adults. Artesunate-pyronaridine versus artemether-lumefantrineIn two multicentre trials, enrolling mainly older children and adults from west and south-central Africa, both artesunate-pyronaridine and artemether-lumefantrine had fewer than 5% PCR adjusted treatment failures during 42 days of follow-up, with no differences between groups (two trials, 1472 participants, low quality evidence). There were fewer new infections during the first 28 days in those given artesunate-pyronaridine (PCR-unadjusted treatment failure: RR 0.60, 95% CI 0.40 to 0.90, two trials, 1720 participants, moderate quality evidence), but no difference was detected over the whole 42 day follow-up (two trials, 1691 participants, moderate quality evidence). Artesunate-pyronaridine versus artesunate plus mefloquineIn one multicentre trial, enrolling mainly older children and adults from South East Asia, both artesunate-pyronaridine and artesunate plus mefloquine had fewer than 5% PCR adjusted treatment failures during 28 days follow-up (one trial, 1187 participants, moderate quality evidence). PCR-adjusted treatment failures were 6% by day 42 for these treated with artesunate-pyronaridine, and 4% for those with artesunate-mefloquine (RR 1.64, 95% CI 0.89 to 3.00, one trial, 1116 participants, low quality evidence). Again, there were fewer new infections during the first 28 days in those given artesunate-pyronaridine (PCR-unadjusted treatment failure: RR 0.35, 95% CI 0.17 to 0.73, one trial, 1720 participants, moderate quality evidence), but no differences were detected over the whole 42 days (one trial, 1146 participants, low quality evidence). Adverse effectsSerious adverse events were uncommon in these trials, with no difference detected between artesunate-pyronaridine and comparator ACTs. The analysis of liver function tests showed biochemical elevation were four times more frequent with artesunate-pyronaridine than with the other antimalarials (RR 4.17, 95% CI 1.38 to 12.62, four trials, 3523 participants, moderate quality evidence). Artesunate-pyronaridine performed well in these trials compared to artemether-lumefantrine and artesunate plus mefloquine, with PCR-adjusted treatment failure at day 28 below the 5% standard set by the WHO. Further efficacy and safety studies in African and Asian children are required to clarify whether this combination is an option for first-line treatment.

Higher Complexity of Infection and Genetic Diversity of Plasmodium vivax Than Plasmodium falciparum Across All Malaria Transmission Zones of Papua New Guinea.

PubMed

Fola, Abebe A; Harrison, G L Abby; Hazairin, Mita Hapsari; Barnadas, Céline; Hetzel, Manuel W; Iga, Jonah; Siba, Peter M; Mueller, Ivo; Barry, Alyssa E

2017-03-01

Abstract Plasmodium falciparum and Plasmodium vivax have varying transmission dynamics that are informed by molecular epidemiology. This study aimed to determine the complexity of infection and genetic diversity of P. vivax and P. falciparum throughout Papua New Guinea (PNG) to evaluate transmission dynamics across the country. In 2008-2009, a nationwide malaria indicator survey collected 8,936 samples from all 16 endemic provinces of PNG. Of these, 892 positive P. vivax samples were genotyped at PvMS16 and PvmspF3 , and 758 positive P. falciparum samples were genotyped at Pfmsp2 . The data were analyzed for multiplicity of infection (MOI) and genetic diversity. Overall, P. vivax had higher polyclonality (71%) and mean MOI (2.32) than P. falciparum (20%, 1.39). These measures were significantly associated with prevalence for P. falciparum but not for P. vivax . The genetic diversity of P. vivax ( PvMS16 : expected heterozygosity = 0.95, 0.85-0.98; PvMsp1F3 : 0.78, 0.66-0.89) was higher and less variable than that of P. falciparum ( Pfmsp2 : 0.89, 0.65-0.97). Significant associations of MOI with allelic richness (rho = 0.69, P = 0.009) and expected heterozygosity (rho = 0.87, P < 0.001) were observed for P. falciparum . Conversely, genetic diversity was not correlated with polyclonality nor mean MOI for P. vivax . The results demonstrate higher complexity of infection and genetic diversity of P. vivax across the country. Although P. falciparum shows a strong association of these parameters with prevalence, a lack of association was observed for P. vivax and is consistent with higher potential for outcrossing of this species.

Malaria and related outcomes in patients with intestinal helminths: a cross-sectional study.

PubMed

Degarege, Abraham; Legesse, Mengistu; Medhin, Girmay; Animut, Abebe; Erko, Berhanu

2012-11-09

The effects of helminth co-infection on malaria in humans remain uncertain. This study aimed to evaluate the nature of association of intestinal helminths with prevalence and clinical outcomes of Plasmodium infection. A cross-sectional study involving 1,065 malaria suspected febrile patients was conducted at Dore Bafeno Health Center, Southern Ethiopia, from December 2010 to February 2011. Plasmodium and intestinal helminth infections were diagnosed using Giemsa-stained blood films and Kato-Katz technique, respectively. Haemoglobin level was determined using a haemocue machine. Among 1,065 malaria suspected febrile patients, 28.8% were positive for Plasmodium parasites (P. falciparum =13.0%, P. vivax =14.5%, P. falciparum and P. vivax =1.3%). Among 702 patients who provided stool samples, 53.8%, 31.6% and 19.4% were infected with intestinal helminths, Plasmodium alone and with both Plasmodium and intestinal helminths, respectively. The prevalence of infections with Ascaris lumbricoides (A. lumbricoides), Trichuris trichiura (T. trichiura), Schistosoma mansoni (S. mansoni) and hookworm (9.8%) were 35.9%, 15.8%, 11.7% and 9.8%, respectively. Out of the 222 (31.6%) Plasmodium infected cases, 9 (4.1%) had severe malaria. P. falciparum infection was more common in febrile patients infected with A. lumbricoides alone (21.3%), T. trichiura alone (23.1%) and S. mansoni alone (23.1%) compared to those without intestinal helminth infections (9.3%) (p<0.001 for all). Prevalence of non-severe malaria was significantly higher in individuals infected with intestinal helminths than in those who were not infected with intestinal helminths (adjusted OR=1.58, 95% CI=1.13-2.22). The chance of developing non-severe P. falciparum malaria were 2.6, 2.8 and 3.3 times higher in individuals infected with A. lumbricoides alone, T. trichiura alone and S. mansoni alone, respectively, compared to intestinal helminth-free individuals (p<0.05 for all). The odds ratio for being infected with non-severe P. falciparum increased with the number of intestinal helminth species (p<0.001). Mean Plasmodium density among intestinal helminth infected individuals was significantly increased with the number of intestinal helminths species (p=0.027). Individuals who were co-infected with different species of intestinal helminths and Plasmodium showed lower mean haemoglobin concentration than individuals who were infected only with Plasmodium. Infections with A. lumbricoides, T. trichiura and S. mansoni were positively associated with P. falciparum infection. However, further studies are required to investigate how these helminths could contribute to increased prevalence of P. falciparum infection.

Malaria and related outcomes in patients with intestinal helminths: a cross-sectional study

PubMed Central

2012-01-01

Background The effects of helminth co-infection on malaria in humans remain uncertain. This study aimed to evaluate the nature of association of intestinal helminths with prevalence and clinical outcomes of Plasmodium infection. Methods A cross-sectional study involving 1,065 malaria suspected febrile patients was conducted at Dore Bafeno Health Center, Southern Ethiopia, from December 2010 to February 2011. Plasmodium and intestinal helminth infections were diagnosed using Giemsa-stained blood films and Kato-Katz technique, respectively. Haemoglobin level was determined using a haemocue machine. Results Among 1,065 malaria suspected febrile patients, 28.8% were positive for Plasmodium parasites (P. falciparum =13.0%, P. vivax =14.5%, P. falciparum and P. vivax =1.3%). Among 702 patients who provided stool samples, 53.8%, 31.6% and 19.4% were infected with intestinal helminths, Plasmodium alone and with both Plasmodium and intestinal helminths, respectively. The prevalence of infections with Ascaris lumbricoides (A. lumbricoides), Trichuris trichiura (T. trichiura), Schistosoma mansoni (S. mansoni) and hookworm (9.8%) were 35.9%, 15.8%, 11.7% and 9.8%, respectively. Out of the 222 (31.6%) Plasmodium infected cases, 9 (4.1%) had severe malaria. P. falciparum infection was more common in febrile patients infected with A. lumbricoides alone (21.3%), T. trichiura alone (23.1%) and S. mansoni alone (23.1%) compared to those without intestinal helminth infections (9.3%) (p<0.001 for all). Prevalence of non-severe malaria was significantly higher in individuals infected with intestinal helminths than in those who were not infected with intestinal helminths (adjusted OR=1.58, 95% CI=1.13-2.22). The chance of developing non-severe P. falciparum malaria were 2.6, 2.8 and 3.3 times higher in individuals infected with A. lumbricoides alone, T. trichiura alone and S. mansoni alone, respectively, compared to intestinal helminth-free individuals (p<0.05 for all). The odds ratio for being infected with non-severe P. falciparum increased with the number of intestinal helminth species (p<0.001). Mean Plasmodium density among intestinal helminth infected individuals was significantly increased with the number of intestinal helminths species (p=0.027). Individuals who were co-infected with different species of intestinal helminths and Plasmodium showed lower mean haemoglobin concentration than individuals who were infected only with Plasmodium. Conclusions Infections with A. lumbricoides, T. trichiura and S. mansoni were positively associated with P. falciparum infection. However, further studies are required to investigate how these helminths could contribute to increased prevalence of P. falciparum infection. PMID:23136960

Anaemia following Artemisinin-Based Combination Treatments of Uncomplicated Plasmodium falciparum Malaria in Children: Temporal Patterns of Haematocrit and the Use of Uncomplicated Hyperparasitaemia as a Model for Evaluating Late-Appearing Anaemia.

PubMed

Sowunmi, Akin; Akano, Kazeem; Ntadom, Godwin; Ayede, Adejumoke; Oguche, Stephen; Agomo, Chimere; Okafor, Henrietta; Watila, Ismaila; Meremikwu, Martin; Ogala, William; Agomo, Philip; Adowoye, Elsie; Fatunmbi, Bayo; Aderoyeje, Temitope; Happi, Christian; Gbotosho, Grace; Folarin, Onikepe

2017-01-01

In severe malaria, intravenous artesunate may cause delayed haemolytic anaemia but there has been little evaluation of the propensity of oral artemisinin-based combination treatments (ACTs) to cause late-appearing anaemia. The frequency of anaemia (haematocrit <30%), and temporal changes in haematocrit were evaluated in 1,191 malarious children following ACTs. "Haematocrit conservation" was evaluated by using the fall in haematocrit/1,000 asexual parasites cleared from the peripheral blood (FIH/1,000 asexual parasites cpb), and the ratio of the average haematocrit (on the first 3 days of starting treatment):total parasitaemia cleared. The frequency of anaemia decreased significantly following treatment. FIH/1,000 asexual parasites cpb, average haematocrit:total parasitaemia cleared, and mean haematocrit 5 weeks after treatment began were significantly lower in hyperparasitaemic children than in children without hyperparasitaemia, suggesting haematocrit conservation during treatment followed later by a loss of haematocrit. Asymptomatic late-appearing anaemia occurred in 6% of the children. Artesunate-amodiaquine and artemether-lumefantrine contribute to haematocrit conservation at high parasitaemias but may cause late-appearing anaemia. © 2017 S. Karger AG, Basel.

Plasmodium falciparum Malaria, Southern Algeria, 2007

PubMed Central

Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, Cécile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

2010-01-01

An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria. PMID:20113565

Ingested human insulin inhibits the mosquito NF-¿B-dependent immune response to Plasmodium falciparum

USDA-ARS?s Scientific Manuscript database

We showed previously that ingested human insulin activates the insulin/IGF-1 signaling pathway in Anopheles stephensi and increases the susceptibility of these mosquitoes to Plasmodium falciparum. In other organisms insulin can alter immune responsiveness through regulation of NF-kB transcription fa...

Antimalarial Activity of KAF156 in Falciparum and Vivax Malaria.

PubMed

White, Nicholas J; Duong, Tran T; Uthaisin, Chirapong; Nosten, François; Phyo, Aung P; Hanboonkunupakarn, Borimas; Pukrittayakamee, Sasithon; Jittamala, Podjanee; Chuthasmit, Kittiphum; Cheung, Ming S; Feng, Yiyan; Li, Ruobing; Magnusson, Baldur; Sultan, Marc; Wieser, Daniela; Xun, Xiaolei; Zhao, Rong; Diagana, Thierry T; Pertel, Peter; Leong, F Joel

2016-09-22

KAF156 belongs to a new class of antimalarial agents (imidazolopiperazines), with activity against asexual and sexual blood stages and the preerythrocytic liver stages of malarial parasites. We conducted a phase 2, open-label, two-part study at five centers in Thailand and Vietnam to assess the antimalarial efficacy, safety, and pharmacokinetic profile of KAF156 in adults with acute Plasmodium vivax or P. falciparum malaria. Assessment of parasite clearance rates in cohorts of patients with vivax or falciparum malaria who were treated with multiple doses (400 mg once daily for 3 days) was followed by assessment of the cure rate at 28 days in a separate cohort of patients with falciparum malaria who received a single dose (800 mg). Median parasite clearance times were 45 hours (interquartile range, 42 to 48) in 10 patients with falciparum malaria and 24 hours (interquartile range, 20 to 30) in 10 patients with vivax malaria after treatment with the multiple-dose regimen and 49 hours (interquartile range, 42 to 54) in 21 patients with falciparum malaria after treatment with the single dose. Among the 21 patients who received the single dose and were followed for 28 days, 1 had reinfection and 7 had recrudescent infections (cure rate, 67%; 95% credible interval, 46 to 84). The mean (±SD) KAF156 terminal elimination half-life was 44.1±8.9 hours. There were no serious adverse events in this small study. The most common adverse events included sinus bradycardia, thrombocytopenia, hypokalemia, anemia, and hyperbilirubinemia. Vomiting of grade 2 or higher occurred in 2 patients, 1 of whom discontinued treatment because of repeated vomiting after receiving the single 800-mg dose. More adverse events were reported in the single-dose cohort, which had longer follow-up, than in the multiple-dose cohorts. KAF156 showed antimalarial activity without evident safety concerns in a small number of adults with uncomplicated P. vivax or P. falciparum malaria. (Funded by Novartis and others; ClinicalTrials.gov number, NCT01753323 .).

Bioinformatics analysis for structure and function of CPR of Plasmodium falciparum.

PubMed

Fan, Zhigang; Zhang, Lingmin; Yan, Guogang; Wu, Qiang; Gan, Xiufeng; Zhong, Saifeng; Lin, Guifen

2011-02-01

To analyse the structure and function of NADPH-cytochrome p450 reductase (CYPOR or CPR) from Plasmodium falciparum (Pf), and to predict its' drug target and vaccine target. The structure, function, drug target and vaccine target of CPR from Plasmodium falciparum were analyzed and predicted by bioinformatics methods. PfCPR, which was older CPR, had close relationship with the CPR from other Plasmodium species, but it was distant from its hosts, such as Homo sapiens and Anopheles. PfCPR was located in the cellular nucleus of Plasmodium falciparum. 335aa-352aa and 591aa - 608aa were inserted the interior side of the nuclear membrane, while 151aa-265aa was located in the nucleolus organizer regions. PfCPR had 40 function sites and 44 protein-protein binding sites in amino acid sequence. The teriary structure of 1aa-700aa was forcep-shaped with wings. 15 segments of PfCPR had no homology with Homo sapien CPR and most were exposed on the surface of the protein. These segments had 25 protein-protein binding sites. While 13 other segments all possessed function sites. The evolution or genesis of Plasmodium falciparum is earlier than those of Homo sapiens. PfCPR is a possible resistance site of antimalarial drug and may involve immune evasion, which is associated with parasite of sporozoite in hepatocytes. PfCPR is unsuitable as vaccine target, but it has at least 13 ideal drug targets. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Artemisinin resistance at the China-Myanmar border and association with mutations in the K13 propeller gene.

PubMed

Wang, Zenglei; Wang, Yingna; Cabrera, Mynthia; Zhang, Yanmei; Gupta, Bhavna; Wu, Yanrui; Kemirembe, Karen; Hu, Yue; Liang, Xiaoying; Brashear, Awtum; Shrestha, Sony; Li, Xiaolian; Miao, Jun; Sun, Xiaodong; Yang, Zhaoqing; Cui, Liwang

2015-11-01

Artemisinin resistance in Plasmodium falciparum parasites in Southeast Asia is a major concern for malaria control. Its emergence at the China-Myanmar border, where there have been more than 3 decades of artemisinin use, has yet to be investigated. Here, we comprehensively evaluated the potential emergence of artemisinin resistance and antimalarial drug resistance status in P. falciparum using data and parasites from three previous efficacy studies in this region. These efficacy studies of dihydroartemisinin-piperaquine combination and artesunate monotherapy of uncomplicated falciparum malaria in 248 P. falciparum patients showed an overall 28-day adequate clinical and parasitological response of >95% and day 3 parasite-positive rates of 6.3 to 23.1%. Comparison of the 57 K13 sequences (24 and 33 from day 3 parasite-positive and -negative cases, respectively) identified nine point mutations in 38 (66.7%) samples, of which F446I (49.1%) and an N-terminal NN insertion (86.0%) were predominant. K13 propeller mutations collectively, the F446I mutation alone, and the NN insertion all were significantly associated with day 3 parasite positivity. Increased ring-stage survival determined using the ring-stage survival assay (RSA) was highly associated with the K13 mutant genotype. Day 3 parasite-positive isolates had ∼10 times higher ring survival rates than day 3 parasite-negative isolates. Divergent K13 mutations suggested independent evolution of artemisinin resistance. Taken together, this study confirmed multidrug resistance and emergence of artemisinin resistance in P. falciparum at the China-Myanmar border. RSA and K13 mutations are useful phenotypic and molecular markers for monitoring artemisinin resistance. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Self-reactivities to the non-erythroid alpha spectrin correlate with cerebral malaria in Gabonese children.

PubMed

Guiyedi, Vincent; Chanseaud, Youri; Fesel, Constantin; Snounou, Georges; Rousselle, Jean-Claude; Lim, Pharat; Koko, Jean; Namane, Abdelkader; Cazenave, Pierre-André; Kombila, Maryvonne; Pied, Sylviane

2007-04-25

Hypergammaglobulinemia and polyclonal B-cell activation commonly occur in Plasmodium sp. infections. Some of the antibodies produced recognize self-components and are correlated with disease severity in P. falciparum malaria. However, it is not known whether some self-reactive antibodies produced during P. falciparum infection contribute to the events leading to cerebral malaria (CM). We show here a correlation between self-antibody responses to a human brain protein and high levels of circulating TNF alpha (TNFalpha), with the manifestation of CM in Gabonese children. To study the role of self-reactive antibodies associated to the development of P. falciparum cerebral malaria, we used a combination of quantitative immunoblotting and multivariate analysis to analyse correlation between the reactivity of circulating IgG with a human brain protein extract and TNFalpha concentrations in cohorts of uninfected controls (UI) and P. falciparum-infected Gabonese children developing uncomplicated malaria (UM), severe non-cerebral malaria (SNCM), or CM. The repertoire of brain antigens recognized by plasma IgGs was more diverse in infected than in UI individuals. Anti-brain reactivity was significantly higher in the CM group than in the UM and SNCM groups. IgG self-reactivity to brain antigens was also correlated with plasma IgG levels and age. We found that 90% of CM patients displayed reactivity to a high-molecular mass band containing the spectrin non-erythroid alpha chain. Reactivity with this band was correlated with high TNFalpha concentrations in CM patients. These results strongly suggest that an antibody response to brain antigens induced by P. falciparum infection may be associated with pathogenic mechanisms in patients developing CM.

Self-Reactivities to the Non-Erythroid Alpha Spectrin Correlate with Cerebral Malaria in Gabonese Children

PubMed Central

Fesel, Constantin; Snounou, Georges; Rousselle, Jean-Claude; Lim, Pharat; Koko, Jean; Namane, Abdelkader; Cazenave, Pierre-André; Kombila, Maryvonne; Pied, Sylviane

2007-01-01

Background Hypergammaglobulinemia and polyclonal B-cell activation commonly occur in Plasmodium sp. infections. Some of the antibodies produced recognize self-components and are correlated with disease severity in P. falciparum malaria. However, it is not known whether some self-reactive antibodies produced during P. falciparum infection contribute to the events leading to cerebral malaria (CM). We show here a correlation between self-antibody responses to a human brain protein and high levels of circulating TNF alpha (TNFα), with the manifestation of CM in Gabonese children. Methodology To study the role of self-reactive antibodies associated to the development of P. falciparum cerebral malaria, we used a combination of quantitative immunoblotting and multivariate analysis to analyse correlation between the reactivity of circulating IgG with a human brain protein extract and TNFα concentrations in cohorts of uninfected controls (UI) and P. falciparum-infected Gabonese children developing uncomplicated malaria (UM), severe non-cerebral malaria (SNCM), or CM. Results/Conclusion The repertoire of brain antigens recognized by plasma IgGs was more diverse in infected than in UI individuals. Anti-brain reactivity was significantly higher in the CM group than in the UM and SNCM groups. IgG self-reactivity to brain antigens was also correlated with plasma IgG levels and age. We found that 90% of CM patients displayed reactivity to a high-molecular mass band containing the spectrin non-erythroid alpha chain. Reactivity with this band was correlated with high TNFα concentrations in CM patients. These results strongly suggest that an antibody response to brain antigens induced by P. falciparum infection may be associated with pathogenic mechanisms in patients developing CM. PMID:17460756

Global sequence diversity of the lactate dehydrogenase gene in Plasmodium falciparum.

PubMed

Simpalipan, Phumin; Pattaradilokrat, Sittiporn; Harnyuttanakorn, Pongchai

2018-01-09

Antigen-detecting rapid diagnostic tests (RDTs) have been recommended by the World Health Organization for use in remote areas to improve malaria case management. Lactate dehydrogenase (LDH) of Plasmodium falciparum is one of the main parasite antigens employed by various commercial RDTs. It has been hypothesized that the poor detection of LDH-based RDTs is attributed in part to the sequence diversity of the gene. To test this, the present study aimed to investigate the genetic diversity of the P. falciparum ldh gene in Thailand and to construct the map of LDH sequence diversity in P. falciparum populations worldwide. The ldh gene was sequenced for 50 P. falciparum isolates in Thailand and compared with hundreds of sequences from P. falciparum populations worldwide. Several indices of molecular variation were calculated, including the proportion of polymorphic sites, the average nucleotide diversity index (π), and the haplotype diversity index (H). Tests of positive selection and neutrality tests were performed to determine signatures of natural selection on the gene. Mean genetic distance within and between species of Plasmodium ldh was analysed to infer evolutionary relationships. Nucleotide sequences of P. falciparum ldh could be classified into 9 alleles, encoding 5 isoforms of LDH. L1a was the most common allelic type and was distributed in P. falciparum populations worldwide. Plasmodium falciparum ldh sequences were highly conserved, with haplotype and nucleotide diversity values of 0.203 and 0.0004, respectively. The extremely low genetic diversity was maintained by purifying selection, likely due to functional constraints. Phylogenetic analysis inferred the close genetic relationship of P. falciparum to malaria parasites of great apes, rather than to other human malaria parasites. This study revealed the global genetic variation of the ldh gene in P. falciparum, providing knowledge for improving detection of LDH-based RDTs and supporting the candidacy of LDH as a therapeutic drug target.

Evidence of triple mutant Pfdhps ISGNGA haplotype in Plasmodium falciparum isolates from North-east India: An analysis of sulfadoxine resistant haplotype selection.

PubMed

Das, Manuj K; Chetry, Sumi; Kalita, Mohan C; Dutta, Prafulla

2016-12-01

North-east region of India has consistent role in the spread of multi drug resistant Plasmodium (P.) falciparum to other parts of Southeast Asia. After rapid clinical treatment failure of Artemisinin based combination therapy-Sulphadoxine/Pyrimethamine (ACT-SP) chemoprophylaxis, Artemether-Lumefantrine (ACT-AL) combination therapy was introduced in the year 2012 in this region for the treatment of uncomplicated P. falciparum malaria. In a DNA sequencing based polymorphism analysis, seven codons of P. falciparum dihydropteroate synthetase ( Pf dhps) gene were screened in a total of 127 P. falciparum isolates collected from Assam, Arunachal Pradesh and Tripura of North-east India during the year 2014 and 2015 to document current sulfadoxine resistant haplotypes. Sequences were analyzed to rearrange both nucleotide and protein haplotypes. Molecular diversity indices were analyzed in DNA Sequence Polymorphism software (DnaSP) on the basis of Pf dhps gene sequences. Disappearance from selective neutrality was assessed based on the ratio of non-synonomous to synonomous nucleotide substitutions [dN/dS ratio]. Moreover, two-tailed Z test was performed in search of the significance for probability of rejecting null hypothesis of strict neutrality [dN = dS]. Presence of mutant P. falciparum multidrug resistance protein1 ( Pf mdr1) was also checked in those isolates that were present with new Pf dhps haplotypes. Phylogenetic relationship based on Pf dhps gene was reconstructed in Molecular Evolutionary Genetics Analysis (MEGA). Among eight different sulfadoxine resistant haplotypes found, IS GNG A haplotype was documented in a total of five isolates from Tripura with association of a new mutant M538 R allele. Sequence analysis of Pf mdr1 gene in these five isolates came to notice that not all but only one isolate was mutant at codon 86 (N86 Y ; Y YSND) in the multidrug resistance protein. Molecular diversity based on Pf dhps haplotypes revealed that P. falciparum populations in Assam and Tripura were under balancing selection for sulfadoxine resistant haplotypes but population from Arunachal Pradesh was under positive selection with comparatively high haplotype diversity ( h  = 0.870). In reconstructed phylogenetic analysis, isolates having IS GNG A haplotype were grouped into two separate sub-clusters from the other isolates based on their genetic distances and diversities. This study suggests that sulfadoxine resistant isolates are still migrating from its epicenter to the other parts of Southeast Asia and hence control and elimination of the drug resistant isolates have become impedimental. Moreover, P. falciparum populations in different areas may undergo selection of particular sulfadoxine resistant haplotypes either in the presence of drug or after its removal to maintain their plasticity.

Evaluation of the rapid diagnostic test CareStart pLDH Malaria (Pf-pLDH/pan-pLDH) for the diagnosis of malaria in a reference setting.

PubMed

Heutmekers, Marloes; Gillet, Philippe; Maltha, Jessica; Scheirlinck, Annelies; Cnops, Lieselotte; Bottieau, Emmanuel; Van Esbroeck, Marjan; Jacobs, Jan

2012-06-18

The present study evaluated CareStart pLDH Malaria, a three-band rapid diagnostic test detecting Plasmodium falciparum-specific parasite lactate dehydrogenase (Pf-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH) in a reference setting. CareStart pLDH was retrospectively and prospectively assessed with a panel of stored (n=498) and fresh (n=77) blood samples obtained in international travelers suspected of malaria. Both panels comprised all four Plasmodium species; the retrospective panel comprised also Plasmodium negative samples. The reference method was microscopy corrected by PCR. The prospective panel was run side-to-side with OptiMAL (Pf-pLDH/pan-pLDH) and SDFK60 (histidine-rich protein-2 (HRP-2)/pan-pLDH). In the retrospective evaluation, overall sensitivity for P. falciparum samples (n=247) was 94.7%, reaching 98.7% for parasite densities>1,000/μl. Most false negative results occurred among samples with pure gametocytaemia (2/12, 16.7%) and at parasite densities ≤ 100/μl (7/12, 58.3%). None of the Plasmodium negative samples (n=96) showed visible test lines. Sensitivities for Plasmodium vivax (n=70), Plasmodium ovale (n=69) and Plasmodium malariae (n=16) were 74.3%, 31.9% and 25.0% respectively. Wrong species identification occurred in 10 (2.5%) samples and was mainly due to P. vivax samples reacting with the Pf-pLDH test line. Overall, Pf-pLDH test lines showed higher line intensities compared to the pan-pLDH lines (67.9% and 23.0% medium and strong line intensities for P. falciparum). In the prospective panel (77 Plasmodium-positive samples), CareStart pLDH showed higher sensitivities for P. falciparum compared to OptiMAL (p=0.008), lower sensitivities for P. falciparum as compare to SDFK60 (although not reaching statistical significance, p=0.08) and higher sensitivities for P. ovale compared to both OptiMAL (p=0.03) and SDFK60 (p=0.01). Inter-observer and test reproducibility were good to excellent. CareStart pLDH performed excellent for the detection of P. falciparum, well for P. vivax, but poor for P. ovale and P. malariae.

Drugs in Development for Malaria.

PubMed

Ashley, Elizabeth A; Phyo, Aung Pyae

2018-05-25

The last two decades have seen a surge in antimalarial drug development with product development partnerships taking a leading role. Resistance of Plasmodium falciparum to the artemisinin derivatives, piperaquine and mefloquine in Southeast Asia means new antimalarials are needed with some urgency. There are at least 13 agents in clinical development. Most of these are blood schizonticides for the treatment of uncomplicated falciparum malaria, under evaluation either singly or as part of two-drug combinations. Leading candidates progressing through the pipeline are artefenomel-ferroquine and lumefantrine-KAF156, both in Phase 2b. Treatment of severe malaria continues to rely on two parenteral drugs with ancient forebears: artesunate and quinine, with sevuparin being evaluated as an adjuvant therapy. Tafenoquine is under review by stringent regulatory authorities for approval as a single-dose treatment for Plasmodium vivax relapse prevention. This represents an advance over standard 14-day primaquine regimens; however, the risk of acute haemolytic anaemia in patients with glucose-6-phosphate dehydrogenase deficiency remains. For disease prevention, several of the newer agents show potential but are unlikely to be recommended for use in the main target groups of pregnant women and young children for some years. Latest predictions are that the malaria burden will continue to be high in the coming decades. This fact, coupled with the repeated loss of antimalarials to resistance, indicates that new antimalarials will be needed for years to come. Failure of the artemisinin-based combinations in Southeast Asia has stimulated a reappraisal of current approaches to combination therapy for malaria with incorporation of three or more drugs in a single treatment under consideration.

Gametocyte Development and Carriage in Ghanaian Individuals with Uncomplicated Plasmodium falciparum Malaria.

PubMed

Dinko, Bismarck; Ansah, Felix; Agyare-Kwabi, Comfort; Tagboto, Senyo; Amoah, Linda Eva; Urban, Britta C; Sutherland, Colin J; Awandare, Gordon A; Williamson, Kim C; Binka, Fred N; Deitsch, Kirk W

2018-04-23

Plasmodium falciparum gametocytes develop over 9-12 days while sequestered in deep tissues. On emergence into the bloodstream, they circulate for varied amounts of time during which certain host factors might influence their further development. We aimed to evaluate the potential association of patient clinical parameters with gametocyte development and carriage via in vivo methods. Seventy-two patients were enrolled from three hospitals in the Volta region of Ghana in 2016. Clinical parameters were documented for all patients, and gametocyte prevalence by microscopy was estimated at 12.5%. By measuring RNA transcripts representing two distinct gametocyte developmental stages using reverse transcriptase quantitative PCR (RT-qPCR), we obtained a more precise estimate of gametocyte carriage while also inferring gametocyte maturation. Fifty-three percent of the study participants harbored parasites expressing transcripts of the immature gametocyte-specific gene ( PF3D7_1477700 ), whereas 36% harbored PF3D7_1438800 RNA-positive parasites, which is enriched in mid and mature gametocytes, suggesting the presence of more immature stages. Linear logistic regression showed that patients older than 5 years but less than 16 years were more likely to carry gametocytes expressing both PF3D7_1477700 and PF3D7_1438800 compared with younger participants, and gametocytemia was more likely in mildly anemic individuals compared with those with severe/moderate anemia. These data provide further evidence that a greater number of malaria patients harbor gametocytes than typically estimated by microscopy and suggest a possible association between age, fever, anemia, and gametocytemia.

Reconstructing the Qo Site of Plasmodium falciparum bc 1 Complex in the Yeast Enzyme

PubMed Central

Vallières, Cindy; Fisher, Nicholas; Meunier, Brigitte

2013-01-01

The bc 1 complex of the mitochondrial respiratory chain is essential for Plasmodium falciparum proliferation, the causative agent of human malaria. Therefore, this enzyme is an attractive target for antimalarials. However, biochemical investigations of the parasite enzyme needed for the study of new drugs are challenging. In order to facilitate the study of new compounds targeting the enzyme, we are modifying the inhibitor binding sites of the yeast Saccharomyces cerevisiae to generate a complex that mimics the P. falciparum enzyme. In this study we focused on its Qo pocket, the site of atovaquone binding which is a leading antimalarial drug used in treatment and causal prophylaxis. We constructed and studied a series of mutants with modified Qo sites where yeast residues have been replaced by P. falciparum equivalents, or, for comparison, by human equivalents. Mitochondria were prepared from the yeast Plasmodium-like and human-like Qo mutants. We measured the bc 1 complex sensitivity to atovaquone, azoxystrobin, a Qo site targeting fungicide active against P. falciparum and RCQ06, a quinolone-derivative inhibitor of P. falciparum bc 1 complex.The data obtained highlighted variations in the Qo site that could explain the differences in inhibitor sensitivity between yeast, plasmodial and human enzymes. We showed that the yeast Plasmodium-like Qo mutants could be useful and easy-to-use tools for the study of that class of antimalarials. PMID:23951230

Quinine Pharmacokinetics and Pharmacodynamics in Children with Malaria Caused by Plasmodium falciparum

PubMed Central

Le Jouan, M.; Jullien, V.; Tetanye, E.; Tran, A.; Rey, E.; Tréluyer, J.-M.; Tod, M.; Pons, G.

2005-01-01

The aim of the present study was to assess the pharmacokinetics and the efficacy of a shorter than usual 5-day quinine treatment given orally to children in Cameroon with malaria caused by Plasmodium falciparum. Quinine (8.3 mg of base per kg of body weight every 8 h) was administered as a 2% formiate salt syrup for 5 days to 30 children (age range, 0.55 to 6.7 years) with uncomplicated falciparum malaria (initial parasitemia, 1.4 × 103 to 1.8 × 105/μl). Quinine concentrations in plasma samples (five to nine per patient) were measured by liquid chromatography on days 1 to 3. Parasitemia was counted on days 0, 1, 2, 3, 4, 7, and 14. Pharmacokinetic and pharmacodynamic data were analyzed by population approaches by using NONMEM and WinBugs, respectively. The kinetics of quinine were best described by a one-compartment model with time-varying protein binding. Clearance and the volume of distribution were positively correlated with body weight and increased over time. Parasitemia was undetectable from day 3 to 14 in all children. The time to a 4-log reduction of the initial level of parasitemia (Ter) was related to the average quinine concentration from 0 to 72 h (Cav) as Ter = Tmin [1 + (C50/Cav)s], where sigmoidicity (s) is equal to 2, Tmin is the time to eradication at infinite Cav, and C50 is the value of Cav for which Ter is twice Tmin. The C50 distribution was unimodal, and all C50 values were less than 8 mg/liter, while Cav ranged from 5.9 to 18.3 mg/liter. The median (10th to 90th percentile) Ter was 47 h (range, 39 to 76 h). The efficacy of a 5-day treatment course should be evaluated in a larger clinical trial. PMID:16127036

Malaria epidemiology in central Myanmar: identification of a multi-species asymptomatic reservoir of infection.

PubMed

Ghinai, Isaac; Cook, Jackie; Hla, Teddy Tun Win; Htet, Hein Myat Thu; Hall, Tom; Lubis, Inke Nd; Ghinai, Rosanna; Hesketh, Therese; Naung, Ye; Lwin, Mya Mya; Latt, Tint Swe; Heymann, David L; Sutherland, Colin J; Drakeley, Chris; Field, Nigel

2017-01-05

The spread of artemisinin-resistant Plasmodium falciparum is a global health concern. Myanmar stands at the frontier of artemisinin-resistant P. falciparum. Myanmar also has the highest reported malaria burden in Southeast Asia; it is integral in the World Health Organization's plan to eliminate malaria in Southeast Asia, yet few epidemiological data exist for the general population in Myanmar. This cross-sectional, probability household survey was conducted in Phyu township, Bago Region (central Myanmar), during the wet season of 2013. Interviewers collected clinical and behavioural data, recorded tympanic temperature and obtained dried blood spots for malaria PCR and serology. Plasmodium falciparum positive samples were tested for genetic mutations in the K13 region that may confer artemisinin resistance. Estimated type-specific malaria PCR prevalence and seroprevalence were calculated, with regression analysis to identify risk factors for seropositivity to P. falciparum. Data were weighted to account for unequal selection probabilities. 1638 participants were sampled (500 households). Weighted PCR prevalence was low (n = 41, 2.5%) and most cases were afebrile (93%). Plasmodium falciparum was the most common species (n = 19. 1.1%) and five (26%) P. falciparum samples harboured K13 mutations. Plasmodium knowlesi was detected in 1.0% (n = 16) and Plasmodium vivax was detected in 0.4% (n = 7). Seroprevalence was 9.4% for P. falciparum and 3.1% for P. vivax. Seroconversion to P. falciparum was 0.003/year in the whole population, but 16-fold higher in men over 23 years old (LR test p = 0.016). This is the first population-based seroprevalence study from central Myanmar. Low overall prevalence was discovered. However, these data suggest endemic transmission continues, probably associated with behavioural risk factors amongst working-age men. Genetic mutations associated with P. falciparum artemisinin resistance, the presence of P. knowlesi and discrete demographic risk groups present opportunities and challenges for malaria control. Responses targeted to working-age men, capable of detecting sub-clinical infections, and considering all species will facilitate malaria elimination in this setting.

Treatment Failure of Dihydroartemisinin/Piperaquine for Plasmodium falciparum Malaria, Vietnam.

PubMed

Phuc, Bui Quang; Rasmussen, Charlotte; Duong, Tran Thanh; Dong, Le Than; Loi, Mai Anh; Ménard, Didier; Tarning, Joel; Bustos, Dorina; Ringwald, Pascal; Galappaththy, Gawrie Loku; Thieu, Nguyen Quang

2017-04-01

We conducted a study in Binh Phuoc, Vietnam, in 2015 on the therapeutic efficacy of dihydroartemisinin/piperaquine for Plasmodium falciparum malaria. A high number of treatment failures (14/40) was found, and piperaquine resistance in Vietnam was confirmed. A change in the malaria treatment policy for Vietnam is in process.

Two-Color Flow Cytometric Analysis of Intraerythrocytic Malaria Parasite DNA and Surface Membrane-Associated Antigen in Erythrocytes Infected with Plasmodium falciparum

DTIC Science & Technology

1993-01-01

Antigen in Erythrocytes Infected With Plasmodium falciparum 1 Kovit Pattanapanyasat,2 Rachanee Udomsangpetch, and H. Kyle Webster The Thalassemia Center... Thalassemia Center, Division of Hematology., Siriraj Hospital, 15). Identification of conserved epitopes has important Bangkok 10700. Thailan 93-10832 93 5 4

Structure and Function of Plasmodium falciparum malate dehydrogenase: Role of Critical Amino Acids in C-substrate Binding Procket

USDA-ARS?s Scientific Manuscript database

Malaria parasite thrives on anaerobic fermentation of glucose for energy. Earlier studies from our lab have demonstrated that a cytosolic malate dehydrogenase (PfMDH) with striking similarity to lactate dehydrogenase (PfLDH) might complement PfLDH function in Plasmodium falciparum. The N-terminal g...

Failure of dihydroartemisinin plus piperaquine treatment of falciparum malaria by under-dosing in an overweight patient.

PubMed

Roseau, Jean Baptiste; Pradines, Bruno; Paleiron, Nicolas; Vedy, Serge; Madamet, Marylin; Simon, Fabrice; Javelle, Emilie

2016-09-20

Artemisinin-based combination therapy (ACT) introduced in the mid-1990s has been recommended since 2005 by the World Health Organization as first-line treatment against Plasmodium falciparum in all endemic countries. In 2010, the combination dihydroartemisinin-piperaquine (DP) was recommended for the treatment of uncomplicated P. falciparum malaria. DP is one of the first-line treatments used by the French army since 2013. A case of P. falciparum clinical failure with DP at day 20 was described in a 104 kg French soldier deployed in Djibouti. He was admitted to hospital for supervision of oral treatment with DP [40 mg dihydroartemisinin (DHA) plus 320 mg piperaquine tetraphosphate (PPQ)]. This corresponded to a cumulative dose of 4.6 mg/kg DHA and 37 mg/kg PPQ in the present patient, which is far below the WHO recommended ranges. No mutation was found in the propeller domain of the Kelch 13 (k13) gene, which is associated with artemisinin resistance in Southeast Asia. Pfmdr1 N86, 184F, S1034 and N1042 polymorphisms and haplotype 72-76 CVIET for the pfcrt gene were found in the present case. There was no evidence of resistance to DP. This case confirms the risk of therapeutic failure with dihydroartemisinin-piperaquine by under-dosing in patients weighing more than 100 kg. This therapeutic failure with DP by under-dosing highlighted the importance of appropriate dosing guidelines and the need of research data (efficacy, pharmacokinetics and pharmacodynamics) in over-weight patient group.

The persistence and oscillations of submicroscopic Plasmodium falciparum and Plasmodium vivax infections over time in Vietnam: an open cohort study.

PubMed

Nguyen, Thuy-Nhien; von Seidlein, Lorenz; Nguyen, Tuong-Vy; Truong, Phuc-Nhi; Hung, Son Do; Pham, Huong-Thu; Nguyen, Tam-Uyen; Le, Thanh Dong; Dao, Van Hue; Mukaka, Mavuto; Day, Nicholas Pj; White, Nicholas J; Dondorp, Arjen M; Thwaites, Guy E; Hien, Tran Tinh

2018-05-01

A substantial proportion of Plasmodium species infections are asymptomatic with densities too low to be detectable with standard diagnostic techniques. The importance of such asymptomatic plasmodium infections in malaria transmission is probably related to their duration and density. To explore the duration of asymptomatic plasmodium infections and changes in parasite densities over time, a cohort of participants who were infected with Plasmodium parasites was observed over a 2-year follow-up period. In this open cohort study, inhabitants of four villages in Vietnam were invited to participate in baseline and subsequent 3-monthly surveys up to 24 months, which included the collection of venous blood samples. Samples were batch-screened using ultra-sensitive (u)PCR (lower limit of detection of 22 parasites per mL). Participants found to be infected by uPCR during any of these surveys were invited to join a prospective cohort and provide monthly blood samples. We estimated the persistence of Plasmodium falciparum and Plasmodium vivax infections and changes in parasite densities over a study period of 24 months. Between Dec 1, 2013, and Jan 8, 2016, 356 villagers participated in between one and 22 surveys. These study participants underwent 4248 uPCR evaluations (11·9 tests per participant). 1874 (32%) of 4248 uPCR tests indicated a plasmodium infection; 679 (36%) of 1874 tests were P falciparum monoinfections, 507 (27%) were P vivax monoinfections, 463 (25%) were co-infections with P falciparum and P vivax, and 225 (12%) were indeterminate species of Plasmodium. The median duration of P falciparum infection was 2 months (IQR 1-3); after accounting for censoring, participants had a 20% chance of having parasitaemia for 4 months or longer. The median duration of P vivax infection was 6 months (3-9), and participants had a 59% chance of having parasitaemia for 4 months or longer. The parasite densities of persistent infections oscillated; following ultralow-density infections, high-density infections developed frequently. Persistent largely asymptomatic P vivax and P falciparum infections are common in this area of low seasonal malaria transmission. Infections with low-density parasitaemias can develop into much higher density infections at a later time, which are likely to sustain malaria endemicity. The Wellcome Trust, Bill & Melinda Gates Foundation. Copyright © 2018 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.

Plasmodium falciparum in vitro continuous culture conditions: A comparison of parasite susceptibility and tolerance to anti-malarial drugs throughout the asexual intra-erythrocytic life cycle.

PubMed

Duffy, Sandra; Avery, Vicky M

2017-12-01

The continuous culture of Plasmodium falciparum is often seen as a means to an end, that end being to probe the biology of the parasite in question, and ultimately for many in the malaria drug discovery arena, to identify means of killing the parasite in order to treat malaria. In vitro continuous culture of Plasmodium falciparum is a fundamental requirement when undertaking malaria research where the primary objectives utilise viable parasites of a desired lifecycle stage. This investigation, and resulting data, compared the impact culturing Plasmodium falciparum long term (4 months) in different environmental conditions had on experimental outcomes and thus conclusions. The example presented here focused specifically on the effect culture conditions had on the in vitro tolerance of Plasmodium falciparum to standard anti-malarial drugs, including artemisinin and lumefantrine. Historical data from an independent experiment for 3D7-ALB (5% O 2 ) was also compared with that obtained from this study. We concluded that parasites cultured for several months in media supplemented with a serum substitute such as Albumax II ® or within hyperoxic conditions (21% O 2 ), demonstrate highly variable responses to artemisinin and lumefantrine but not all anti-malarial drugs, when compared to those cultured in human serum in combination with Albumax II ® under normoxic conditions (5% O 2 ) for the parasite. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Very high carriage of gametocytes in asymptomatic low-density Plasmodium falciparum and P. vivax infections in western Thailand.

PubMed

Nguitragool, Wang; Mueller, Ivo; Kumpitak, Chalermpon; Saeseu, Teerawat; Bantuchai, Sirasate; Yorsaeng, Ritthideach; Yimsamran, Surapon; Maneeboonyang, Wanchai; Sa-Angchai, Patiwat; Chaimungkun, Wutthichai; Rukmanee, Prasert; Puangsa-Art, Supalarp; Thanyavanich, Nipon; Koepfli, Cristian; Felger, Ingrid; Sattabongkot, Jetsumon; Singhasivanon, Pratap

2017-10-24

Low-density asymptomatic infections of Plasmodium spp. are common in low endemicity areas worldwide, but outside Africa, their contribution to malaria transmission is poorly understood. Community-based studies with highly sensitive molecular diagnostics are needed to quantify the asymptomatic reservoir of Plasmodium falciparum and P. vivax infections in Thai communities. A cross-sectional survey of 4309 participants was conducted in three endemic areas in Kanchanaburi and Ratchaburi provinces of Thailand in 2012. The presence of P. falciparum and P. vivax parasites was determined using 18S rRNA qPCR. Gametocytes were also detected by pfs25 / pvs25 qRT-PCRs. A total of 133 individuals were found infected with P. vivax (3.09%), 37 with P. falciparum (0.86%), and 11 with mixed P. vivax/ P. falciparum (0.26%). The clear majority of both P. vivax (91.7%) and P. falciparum (89.8%) infections were not accompanied by any febrile symptoms. Infections with either species were most common in adolescent and adult males. Recent travel to Myanmar was highly associated with P. falciparum (OR = 9.0, P = 0.001) but not P. vivax infections (P = 0.13). A large number of P. vivax (71.5%) and P. falciparum (72.0%) infections were gametocyte positive by pvs25/pfs25 qRT-PCR. Detection of gametocyte-specific pvs25 and pfs25 transcripts was strongly dependent on parasite density. pvs25 transcript numbers, a measure of gametocyte density, were also highly correlated with parasite density (r 2  = 0.82, P < 0.001). Asymptomatic infections with Plasmodium spp. were common in western Thai communities in 2012. The high prevalence of gametocytes indicates that these infections may contribute substantially to the maintenance of local malaria transmission.

Spatial and space-time distribution of Plasmodium vivax and Plasmodium falciparum malaria in China, 2005-2014.

PubMed

Hundessa, Samuel H; Williams, Gail; Li, Shanshan; Guo, Jinpeng; Chen, Linping; Zhang, Wenyi; Guo, Yuming

2016-12-19

Despite the declining burden of malaria in China, the disease remains a significant public health problem with periodic outbreaks and spatial variation across the country. A better understanding of the spatial and temporal characteristics of malaria is essential for consolidating the disease control and elimination programme. This study aims to understand the spatial and spatiotemporal distribution of Plasmodium vivax and Plasmodium falciparum malaria in China during 2005-2009. Global Moran's I statistics was used to detect a spatial distribution of local P. falciparum and P. vivax malaria at the county level. Spatial and space-time scan statistics were applied to detect spatial and spatiotemporal clusters, respectively. Both P. vivax and P. falciparum malaria showed spatial autocorrelation. The most likely spatial cluster of P. vivax was detected in northern Anhui province between 2005 and 2009, and western Yunnan province between 2010 and 2014. For P. falciparum, the clusters included several counties of western Yunnan province from 2005 to 2011, Guangxi from 2012 to 2013, and Anhui in 2014. The most likely space-time clusters of P. vivax malaria and P. falciparum malaria were detected in northern Anhui province and western Yunnan province, respectively, during 2005-2009. The spatial and space-time cluster analysis identified high-risk areas and periods for both P. vivax and P. falciparum malaria. Both malaria types showed significant spatial and spatiotemporal variations. Contrary to P. vivax, the high-risk areas for P. falciparum malaria shifted from the west to the east of China. Further studies are required to examine the spatial changes in risk of malaria transmission and identify the underlying causes of elevated risk in the high-risk areas.

A simple field kit for the determination of drug susceptibility in Plasmodium falciparum.

PubMed

Nguyen-Dinh, P; Magloire, R; Chin, W

1983-05-01

A field kit has been developed which greatly simplifies the performance of the 48-hour in vitro test for drug resistance in Plasmodium falciparum. The kit uses an easily reconstituted lyophilized culture medium, and requires only a fingerprick blood sample. In parallel tests with 13 isolates of P. falciparum in Haiti, the new technique had a success rate equal to that of the previously described method, with comparable results in terms of parasite susceptibility in vitro to chloroquine and pyrimethamine.

Prophylaxis of Plasmodium falciparum Infection in a Human Challenge Model with WR 238605, a New 8-Aminoquinoline Antimalarial

PubMed Central

Brueckner, Ralf P.; Coster, Trinka; Wesche, David L.; Shmuklarsky, Moshe; Schuster, Brian G.

1998-01-01

The prophylactic efficacy of WR 238605, a primaquine analog, was studied with a human Plasmodium falciparum challenge model. A single oral dose of 600 mg, administered 1 day prior to challenge, successfully protected three of four subjects. The fourth subject developed mild, oligosymptomatic malaria on day 31, with drug concentrations one-half of those in the protected individuals. WR 238605 appears to be a promising prophylactic drug for P. falciparum malaria. PMID:9593172

Acyclic Immucillin Phosphonates. Second-Generation Inhibitors of Plasmodium falciparum Hypoxanthine- Guanine-Xanthine Phosphoribosyltransferase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hazelton, Keith Z.; Ho, Meng-Chaio; Cassera, Maria B.

We found that Plasmodium falciparum is the primary cause of deaths from malaria. It is a purine auxotroph and relies on hypoxanthine salvage from the host purine pool. Purine starvation as an antimalarial target has been validated by inhibition of purine nucleoside phosphorylase. Hypoxanthine depletion kills Plasmodium falciparum in cell culture and in Aotus monkey infections. Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) from P. falciparum is required for hypoxanthine salvage by forming inosine 5'-monophosphate, a branchpoint for all purine nucleotide synthesis in the parasite. We present a class of HGXPRT inhibitors, the acyclic immucillin phosphonates (AIPs), and cell permeable AIP prodrugs. The AIPsmore » are simple, potent, selective, and biologically stable inhibitors. The AIP prodrugs block proliferation of cultured parasites by inhibiting the incorporation of hypoxanthine into the parasite nucleotide pool and validates HGXPRT as a target in malaria.« less

A systematic review of transfusion-transmitted malaria in non-endemic areas.

PubMed

Verra, Federica; Angheben, Andrea; Martello, Elisa; Giorli, Giovanni; Perandin, Francesca; Bisoffi, Zeno

2018-01-16

Transfusion-transmitted malaria (TTM) is an accidental Plasmodium infection caused by whole blood or a blood component transfusion from a malaria infected donor to a recipient. Infected blood transfusions directly release malaria parasites in the recipient's bloodstream triggering the development of high risk complications, and potentially leading to a fatal outcome especially in individuals with no previous exposure to malaria or in immuno-compromised patients. A systematic review was conducted on TTM case reports in non-endemic areas to describe the epidemiological characteristics of blood donors and recipients. Relevant articles were retrieved from Pubmed, EMBASE, Scopus, and LILACS. From each selected study the following data were extracted: study area, gender and age of blood donor and recipient, blood component associated with TTM, Plasmodium species, malaria diagnostic method employed, blood donor screening method, incubation period between the infected transfusion and the onset of clinical symptoms in the recipient, time elapsed between the clinical symptoms and the diagnosis of malaria, infection outcome, country of origin of the blood donor and time of the last potential malaria exposure. Plasmodium species were detected in 100 TTM case reports with a different frequency: 45% Plasmodium falciparum, 30% Plasmodium malariae, 16% Plasmodium vivax, 4% Plasmodium ovale, 2% Plasmodium knowlesi, 1% mixed infection P. falciparum/P. malariae. The majority of fatal outcomes (11/45) was caused by P. falciparum whilst the other fatalities occurred in individuals infected by P. malariae (2/30) and P. ovale (1/4). However, non P. falciparum fatalities were not attributed directly to malaria. The incubation time for all Plasmodium species TTM case reports was longer than what expected in natural infections. This difference was statistically significant for P. malariae (p = 0.006). A longer incubation time in the recipient together with a chronic infection at low parasite density of the donor makes P. malariae a subtle but not negligible risk for blood safety aside from P. falciparum. TTM risk needs to be taken into account in order to enhance the safety of the blood supply chain from donors to recipients by means of appropriate diagnostic tools.

Evaluation of a rapid diagnostic test (CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test) for the diagnosis of malaria in a reference setting

PubMed Central

2010-01-01

Background Malaria Rapid Diagnostic Tests (RDTs) are widely used for diagnosing malaria. The present retrospective study evaluated the CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test targeting the Plasmodium falciparum specific antigen histidine-rich protein (HRP-2) and the pan-Plasmodium antigen lactate dehydrogenase (pLDH) in a reference setting. Methods The CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test was evaluated on a collection of samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included were P. falciparum (n = 320), Plasmodium vivax (n = 76), Plasmodium ovale (n = 76), Plasmodium malariae (n = 23) and Plasmodium negative samples (n = 95). Results Overall sensitivity for the detection of P. falciparum was 88.8%, increasing to 94.3% and 99.3% at parasite densities above 100 and 1,000/μl respectively. For P. vivax, P. ovale and P. malariae, overall sensitivities were 77.6%, 18.4% and 30.4% respectively. For P. vivax sensitivity reached 90.2% for parasite densities above 500/μl. Incorrect species identification occurred in 11/495 samples (2.2%), including 8/320 (2.5%) P. falciparum samples which generated only the pan-pLDH line. For P. falciparum samples, 205/284 (72.2%) HRP-2 test lines had strong or medium line intensities, while for all species the pan-pLDH lines were less intense, especially in the case of P. ovale. Agreement between observers was excellent (kappa values > 0.81 for positive and negative readings) and test results were reproducible. The test was easy to perform with good clearing of the background. Conclusion The CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test performed well for the detection of P. falciparum and P. vivax, but sensitivities for P. ovale and P. malariae were poor. PMID:20565816

Evaluation of a rapid diagnostic test (CareStart Malaria HRP-2/pLDH (Pf/pan) Combo Test) for the diagnosis of malaria in a reference setting.

PubMed

Maltha, Jessica; Gillet, Philippe; Bottieau, Emmanuel; Cnops, Lieselotte; van Esbroeck, Marjan; Jacobs, Jan

2010-06-18

Malaria Rapid Diagnostic Tests (RDTs) are widely used for diagnosing malaria. The present retrospective study evaluated the CareStart Malaria HRP-2/pLDH (Pf/pan) Combo Test targeting the Plasmodium falciparum specific antigen histidine-rich protein (HRP-2) and the pan-Plasmodium antigen lactate dehydrogenase (pLDH) in a reference setting. The CareStart Malaria HRP-2/pLDH (Pf/pan) Combo Test was evaluated on a collection of samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included were P. falciparum (n = 320), Plasmodium vivax (n = 76), Plasmodium ovale (n = 76), Plasmodium malariae (n = 23) and Plasmodium negative samples (n = 95). Overall sensitivity for the detection of P. falciparum was 88.8%, increasing to 94.3% and 99.3% at parasite densities above 100 and 1,000/microl respectively. For P. vivax, P. ovale and P. malariae, overall sensitivities were 77.6%, 18.4% and 30.4% respectively. For P. vivax sensitivity reached 90.2% for parasite densities above 500/microl. Incorrect species identification occurred in 11/495 samples (2.2%), including 8/320 (2.5%) P. falciparum samples which generated only the pan-pLDH line. For P. falciparum samples, 205/284 (72.2%) HRP-2 test lines had strong or medium line intensities, while for all species the pan-pLDH lines were less intense, especially in the case of P. ovale. Agreement between observers was excellent (kappa values > 0.81 for positive and negative readings) and test results were reproducible. The test was easy to perform with good clearing of the background. The CareStart Malaria HRP-2/pLDH (Pf/pan) Combo Test performed well for the detection of P. falciparum and P. vivax, but sensitivities for P. ovale and P. malariae were poor.

Evaluation of the Palutop+4 malaria rapid diagnostic test in a non-endemic setting.

PubMed

van Dijk, David P J; Gillet, Philippe; Vlieghe, Erika; Cnops, Lieselotte; van Esbroeck, Marjan; Jacobs, Jan

2009-12-12

Palutop+4 (All. Diag, Strasbourg, France), a four-band malaria rapid diagnostic test (malaria RDT) targeting the histidine-rich protein 2 (HRP-2), Plasmodium vivax-specific parasite lactate dehydrogenase (Pv-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH) was evaluated in a non-endemic setting on stored whole blood samples from international travellers suspected of malaria. Microscopy corrected by PCR was the reference method. Samples include those infected by Plasmodium falciparum (n = 323), Plasmodium vivax (n = 97), Plasmodium ovale (n = 73) and Plasmodium malariae (n = 25) and 95 malaria negative samples. The sensitivities for the diagnosis of P. falciparum, P. vivax, P. malariae and P. ovale were 85.1%, 66.0%, 32.0% and 5.5%. Sensitivities increased at higher parasite densities and reached 90.0% for P. falciparum >100/microl and 83.8% for P. vivax > 500/microl. Fourteen P. falciparum samples reacted with the Pv-pLDH line, one P. vivax sample with the HRP-2 line, and respectively two and four P. ovale and P. malariae samples reacted with the HRP-2 line. Two negative samples gave a signal with the HRP-2 line. Faint and weak line intensities were observed for 129/289 (44.6%) HRP-2 lines in P. falciparum samples, for 50/64 (78.1%) Pv-pLDH lines in P. vivax samples and for 9/13 (69.2%) pan-pLDH lines in P. ovale and P. malariae samples combined. Inter-observer reliabilities for positive and negative readings were excellent for the HRP-2 and Pv-pLDH lines (overall agreement > 92.0% and kappa-values for each pair of readers >or= 0.88), and good for the pan-pLDH line (85.5% overall agreement and kappa-values >or= 0.74). Palutop+4 performed moderately for the detection of P. falciparum and P. vivax, but sensitivities were lower than those of three-band malaria RDTs.

Effect of meteorological variables on Plasmodium vivax and Plasmodium falciparum malaria in outbreak prone districts of Rajasthan, India.

PubMed

Lingala, Mercy A L

Malaria is a public health problem caused by Plasmodium parasite and transmitted by anopheline mosquitoes. Arid and semi-arid regions of western India are prone to malaria outbreaks. Malaria outbreak prone districts viz. Bikaner, Barmer and Jodhpur were selected to study the effect of meteorological variables on Plasmodium vivax and Plasmodium falciparum malaria outbreaks for the period of 2009-2012. The data of monthly malaria cases and meteorological variables was analysed using SPSS 20v. Spearman correlation analysis was conducted to examine the strength of the relationship between meteorological variables, P. vivax and P. falciparum malaria cases. Pearson's correlation analysis was carried out among the meteorological variables to observe the independent effect of each independent variable on the outcome. Results indicate that malaria outbreaks have occurred in Bikaner and Barmer due to continuous rains for more than two months. Rainfall has shown to be an important predictor of malaria outbreaks in Rajasthan. P. vivax is more significantly correlated with rainfall, minimum temperature (P<0.01) and less significantly with relative humidity (P<0.05); whereas P. falciparum is significantly correlated with rainfall, relative humidity (P<0.01) and less significantly with temperature (P<0.05). The determination of the lag period for P. vivax is relative humidity and for P. falciparum is temperature. The lag period between malaria cases and rainfall is shorter for P. vivax than P. falciparum. In conclusion, the knowledge generated is not only useful to take prompt malaria control interventions but also helpful to develop better forecasting model in outbreak prone regions. Copyright © 2017 The Author. Published by Elsevier Ltd.. All rights reserved.

Detection of mixed infection level of Plasmodium falciparum and Plasmodium vivax by SYBR Green I-based real-time PCR in North Gondar, north-west Ethiopia.

PubMed

Tajebe, Addimas; Magoma, Gabriel; Aemero, Mulugeta; Kimani, Francis

2014-10-18

Malaria is caused by five Plasmodium species and transmitted by anopheline mosquitoes. It occurs in single and mixed infections. Mixed infection easily leads to misdiagnosis. Accurate detection of malaria species is vital. Therefore, the study was conducted to determine the level of mixed infection and misdiagnosis of malaria species in the study area using SYBR Green I-based real time PCR. The study was conducted in seven health centres from North Gondar, north-west Ethiopia. The data of all febrile patients, who attended the outpatient department for malaria diagnosis, from October to December 2013, was recorded. Dried blood spots were prepared from 168 positive samples for molecular re-evaluation. Parasite DNA was extracted using a commercial kit and Plasmodium species were re-evaluated with SYBR Green I-based real time PCR to detect mixed infections and misdiagnosed mono-infections. Among 7343 patients who were diagnosed for malaria in six study sites within the second quarter of the Ethiopian fiscal year (2013) 1802 (24.54%) were positive for malaria parasite. Out of this, 1,216 (67.48%) Plasmodium falciparum, 553 (30.68%) Plasmodium vivax and 33 (1.8%) mixed infections of both species were recorded. The result showed high prevalence of P. falciparum and P. vivax, but very low prevalence of mixed infections. Among 168 samples collected on dried blood spot 7 (4.17%) were P. vivax, 158 (94.05%) were P. falciparum and 3 (1.80%) were mixed infections of both species. After re-evaluation 10 (5.95%) P. vivax, 112 (66.67%) P. falciparum, 21 (12.50%) P. falciparum + P. vivax mixed infection, and 17 (10.12%) Plasmodium ovale positive rate was recorded. The re-evaluation showed high level of mixed infection, and misdiagnosis of P. ovale and P. vivax. The result shows that P. falciparum prevalence is higher than P. vivax in the study area. The results, obtained from SYBR Green I-based real time PCR, indicated that the diagnosis efficiency of microscopy is very low for species-specific and mixed infection detection. Therefore, real time PCR-based species diagnosis should be applied for clinical diagnosis and quality control purposes in order to prevent the advent of drug resistant strains due to misdiagnosis and mistreatment.

Epidemic Distribution and Variation of Plasmodium falciparum and Plasmodium vivax Malaria in Hainan, China during 1995–2008

PubMed Central

Xiao, Dan; Long, Yong; Wang, Shanqing; Wu, Kejian; Xu, Dezhong; Li, Haitao; Wang, Guangze; Yan, Yongping

2012-01-01

Hainan Province is the main area threatened by malaria in China. However, the epidemiologic patterns of malaria in this region are not yet defined. In this study, we determined the spatio-temporal distribution and variation of Plasmodium falciparum and Plasmodium vivax malaria in Hainan during 1995–2008 by using wavelet and cluster quantitative approaches. The results indicated a decreasing secular trend and obvious seasonal fluctuation of malaria in Hainan. In addition, the characteristic annual peak of malaria could not be detected after 2005. The southcentral region of Hainan has remained an area of relatively high malaria risk, but the incidence of P. falciparum malaria increased significantly in the southeast and southwest regions during 2002–2008. These findings identify epidemic patterns of malaria in Hainan, and are applicable for designing an effective and dynamic public health campaign to combat malaria in this region. PMID:22869636

Glucose-6-phosphate metabolism in Plasmodium falciparum.

PubMed

Preuss, Janina; Jortzik, Esther; Becker, Katja

2012-07-01

Malaria is still one of the most threatening diseases worldwide. The high drug resistance rates of malarial parasites make its eradication difficult and furthermore necessitate the development of new antimalarial drugs. Plasmodium falciparum is responsible for severe malaria and therefore of special interest with regard to drug development. Plasmodium parasites are highly dependent on glucose and very sensitive to oxidative stress; two observations that drew interest to the pentose phosphate pathway (PPP) with its key enzyme glucose-6-phosphate dehydrogenase (G6PD). A central position of the PPP for malaria parasites is supported by the fact that human G6PD deficiency protects to a certain degree from malaria infections. Plasmodium parasites and the human host possess a complete PPP, both of which seem to be important for the parasites. Interestingly, there are major differences between parasite and human G6PD, making the enzyme of Plasmodium a promising target for antimalarial drug design. This review gives an overview of the current state of research on glucose-6-phosphate metabolism in P. falciparum and its impact on malaria infections. Moreover, the unique characteristics of the enzyme G6PD in P. falciparum are discussed, upon which its current status as promising target for drug development is based. Copyright © 2012 Wiley Periodicals, Inc.

On the Diversity of Malaria Parasites in African Apes and the Origin of Plasmodium falciparum from Bonobos

PubMed Central

Pacheco, M. Andreina; Mugisha, Lawrence; André, Claudine; Halbwax, Michel; Fischer, Anne; Krief, Jean-Michel; Kasenene, John M.; Crandfield, Mike; Cornejo, Omar E.; Chavatte, Jean-Marc; Lin, Clara; Letourneur, Franck; Grüner, Anne Charlotte; McCutchan, Thomas F.; Rénia, Laurent; Snounou, Georges

2010-01-01

The origin of Plasmodium falciparum, the etiological agent of the most dangerous forms of human malaria, remains controversial. Although investigations of homologous parasites in African Apes are crucial to resolve this issue, studies have been restricted to a chimpanzee parasite related to P. falciparum, P. reichenowi, for which a single isolate was available until very recently. Using PCR amplification, we detected Plasmodium parasites in blood samples from 18 of 91 individuals of the genus Pan, including six chimpanzees (three Pan troglodytes troglodytes, three Pan t. schweinfurthii) and twelve bonobos (Pan paniscus). We obtained sequences of the parasites' mitochondrial genomes and/or from two nuclear genes from 14 samples. In addition to P. reichenowi, three other hitherto unknown lineages were found in the chimpanzees. One is related to P. vivax and two to P. falciparum that are likely to belong to distinct species. In the bonobos we found P. falciparum parasites whose mitochondrial genomes indicated that they were distinct from those present in humans, and another parasite lineage related to P. malariae. Phylogenetic analyses based on this diverse set of Plasmodium parasites in African Apes shed new light on the evolutionary history of P. falciparum. The data suggested that P. falciparum did not originate from P. reichenowi of chimpanzees (Pan troglodytes), but rather evolved in bonobos (Pan paniscus), from which it subsequently colonized humans by a host-switch. Finally, our data and that of others indicated that chimpanzees and bonobos maintain malaria parasites, to which humans are susceptible, a factor of some relevance to the renewed efforts to eradicate malaria. PMID:20169187

Multiplicity and molecular epidemiology of Plasmodium vivax and Plasmodium falciparum infections in East Africa.

PubMed

Zhong, Daibin; Lo, Eugenia; Wang, Xiaoming; Yewhalaw, Delenasaw; Zhou, Guofa; Atieli, Harrysone E; Githeko, Andrew; Hemming-Schroeder, Elizabeth; Lee, Ming-Chieh; Afrane, Yaw; Yan, Guiyun

2018-05-02

Parasite genetic diversity and multiplicity of infection (MOI) affect clinical outcomes, response to drug treatment and naturally-acquired or vaccine-induced immunity. Traditional methods often underestimate the frequency and diversity of multiclonal infections due to technical sensitivity and specificity. Next-generation sequencing techniques provide a novel opportunity to study complexity of parasite populations and molecular epidemiology. Symptomatic and asymptomatic Plasmodium vivax samples were collected from health centres/hospitals and schools, respectively, from 2011 to 2015 in Ethiopia. Similarly, both symptomatic and asymptomatic Plasmodium falciparum samples were collected, respectively, from hospitals and schools in 2005 and 2015 in Kenya. Finger-pricked blood samples were collected and dried on filter paper. Long amplicon (> 400 bp) deep sequencing of merozoite surface protein 1 (msp1) gene was conducted to determine multiplicity and molecular epidemiology of P. vivax and P. falciparum infections. The results were compared with those based on short amplicon (117 bp) deep sequencing. A total of 139 P. vivax and 222 P. falciparum samples were pyro-sequenced for pvmsp1 and pfmsp1, yielding a total of 21 P. vivax and 99 P. falciparum predominant haplotypes. The average MOI for P. vivax and P. falciparum were 2.16 and 2.68, respectively, which were significantly higher than that of microsatellite markers and short amplicon (117 bp) deep sequencing. Multiclonal infections were detected in 62.2% of the samples for P. vivax and 74.8% of the samples for P. falciparum. Four out of the five subjects with recurrent P. vivax malaria were found to be a relapse 44-65 days after clearance of parasites. No difference was observed in MOI among P. vivax patients of different symptoms, ages and genders. Similar patterns were also observed in P. falciparum except for one study site in Kenyan lowland areas with significantly higher MOI. The study used a novel method to evaluate Plasmodium MOI and molecular epidemiological patterns by long amplicon ultra-deep sequencing. The complexity of infections were similar among age groups, symptoms, genders, transmission settings (spatial heterogeneity), as well as over years (pre- vs. post-scale-up interventions). This study demonstrated that long amplicon deep sequencing is a useful tool to investigate multiplicity and molecular epidemiology of Plasmodium parasite infections.

Plasmodium prevalence and artemisinin-resistant falciparum malaria in Preah Vihear Province, Cambodia: a cross-sectional population-based study.

PubMed

Bosman, Philippe; Stassijns, Jorgen; Nackers, Fabienne; Canier, Lydie; Kim, Nimol; Khim, Saorin; Alipon, Sweet C; Chuor Char, Meng; Chea, Nguon; Dysoley, Lek; Van den Bergh, Rafael; Etienne, William; De Smet, Martin; Ménard, Didier; Kindermans, Jean-Marie

2014-10-06

Intensified efforts are urgently needed to contain and eliminate artemisinin-resistant Plasmodium falciparum in the Greater Mekong subregion. Médecins Sans Frontières plans to support the Ministry of Health in eliminating P. falciparum in an area with artemisinin resistance in the north-east of Cambodia. As a first step, the prevalence of Plasmodium spp. and the presence of mutations associated with artemisinin resistance were evaluated in two districts of Preah Vihear Province. A cross-sectional population-based study using a two-stage cluster sampling was conducted in the rural districts of Chhaeb and Chey Saen, from September to October 2013. In each district, 30 clusters of 10 households were randomly selected. In total, blood samples were collected for 1,275 participants in Chhaeb and 1,224 in Chey Saen. Prevalence of Plasmodium spp. was assessed by PCR on dried blood spots. Plasmodium falciparum positive samples were screened for mutations in the K13-propeller domain gene (PF3D7_1343700). The prevalence of Plasmodium spp. was estimated at 1.49% (95% CI 0.71-3.11%) in Chhaeb and 2.61% (95% CI 1.45-4.66%) in Chey Saen. Twenty-seven samples were positive for P. falciparum, giving a prevalence of 0.16% (95% CI 0.04-0.65) in Chhaeb and 2.04% (95% CI 1.04-3.99%) in Chey Saen. Only 4.0% of the participants testing positive presented with fever or history of fever. K13-propeller domain mutant type alleles (C580Y and Y493H) were found, only in Chey Saen district, in seven out of 11 P. falciparum positive samples with enough genetic material to allow testing. The overall prevalence of P. falciparum was low in both districts but parasites presenting mutations in the K13-propeller domain gene, strongly associated with artemisinin-resistance, are circulating in Chey Saen.The prevalence might be underestimated because of the absentees - mainly forest workers - and the workers of private companies who were not included in the study. These results confirm the need to urgently develop and implement targeted interventions to contain and eliminate P. falciparum malaria in this district before it spreads to other areas.

Ex Vivo Drug Susceptibility of Ferroquine against Chloroquine-Resistant Isolates of Plasmodium falciparum and P. vivax▿

PubMed Central

Marfurt, Jutta; Chalfein, Ferryanto; Prayoga, Pak; Wabiser, Frans; Kenangalem, Enny; Piera, Kim A.; MacHunter, Barbara; Tjitra, Emiliana; Anstey, Nicholas M.; Price, Ric N.

2011-01-01

Ferroquine (FQ; SSR97193), a ferrocene-containing 4-aminoquinoline derivate, has potent in vitro efficacy against chloroquine (CQ)-resistant Plasmodium falciparum and CQ-sensitive P. vivax. In the current study, ex vivo FQ activity was tested in multidrug-resistant P. falciparum and P. vivax field isolates using a schizont maturation assay. Although FQ showed excellent activity against CQ-sensitive and -resistant P. falciparum and P. vivax (median 50% inhibitory concentrations [IC50s], 9.6 nM and 18.8 nM, respectively), there was significant cross-susceptibility with the quinoline-based drugs chloroquine, amodiaquine, and piperaquine (for P. falciparum, r = 0.546 to 0.700, P < 0.001; for P. vivax, r = 0.677 to 0.821, P < 0.001). The observed ex vivo cross-susceptibility is likely to reflect similar mechanisms of drug uptake/efflux and modes of drug action of this drug class. However, the potent activity of FQ against resistant isolates of both P. falciparum and P. vivax highlights a promising role for FQ as a lead antimalarial against CQ-resistant Plasmodium and a useful partner drug for artemisinin-based combination therapy. PMID:21730116

Magnetic isolation of Plasmodium falciparum schizonts iRBCs to generate a high parasitaemia and synchronized in vitro culture.

PubMed

Mata-Cantero, Lydia; Lafuente, Maria J; Sanz, Laura; Rodriguez, Manuel S

2014-03-21

The establishment of methods for an in vitro continuous culture of Plasmodium falciparum is essential for gaining knowledge into its biology and for the development of new treatments. Previously, several techniques have been used to synchronize, enrich and concentrate P. falciparum, although obtaining cultures with high parasitaemia continues being a challenging process. Current methods produce high parasitaemia levels of synchronized P. falciparum cultures by frequent changes of culture medium or reducing the haematocrit. However, these methods are time consuming and sometimes lead to the loss of synchrony. A procedure that combines Percoll and sorbitol treatments, the use of magnetic columns, and the optimization of the in vitro culture conditions to reach high parasitaemia levels for synchronized Plasmodium falciparum cultures is described. A new procedure has been established using P. falciparum 3D7, combining previous reported methodologies to achieve in vitro parasite cultures that reach parasitaemia up to 40% at any intra-erythrocytic stage. High parasitaemia levels are obtained only one day after magnetic column purification without compromising the parasite viability and synchrony. The described procedure allows obtaining a large scale synchronized parasite culture at a high parasitaemia with less manipulations than other methods previously described.

Prevalence of Plasmodium falciparum and non-P. falciparum infections in a highland district in Ghana, and the influence of HIV and sickle cell disease.

PubMed

Owusu, Ewurama D A; Brown, Charles A; Grobusch, Martin P; Mens, Petra

2017-04-24

In the past two decades, there has been a reported decline in malaria in Ghana and the rest of the world; yet it remains the number one cause of mortality and morbidity. Human immuno-deficiency virus (HIV) and sickle cell disease (SCD) share a common geographical space with malaria in sub-Saharan Africa and an interaction between these three conditions has been suggested. This study determined the Plasmodium falciparum and non-P. falciparum status of symptomatic and non-symptomatic residents of Mpraeso in the highlands of Kwahu-South district of Ghana based on evidence of current national decline. The influence of HIV and SCD on malaria was also determined. Participants were 354 symptomatic patients visiting the Kwahu Government Hospital and 360 asymptomatic residents of the district capital. This cross-sectional study was conducted during the minor rainy season (October-December 2014). Rapid diagnostic tests (RDT), blood film microscopy and real-time polymerase chain reaction assessment of blood were done. Participants who tested positive with RDT were treated with artemisinin-based combination therapy; and assessment of venous blood was repeated 7 days after treatment. HIV screening and haemoglobin genotyping was done. Univariate and multivariate regression analysis was used to determine the influence of SCD and HIV. Plasmodium falciparum was prevalent at 124/142 (87.3%). Plasmodium malariae was the only non-falciparum species detected at 18/142 (12.7%). HIV and SCD did not significantly increase odds of malaria infection. However, the use of ITN and recent anti-malarial intake significantly decreased the odds of being malaria infected by 0.45-fold and 0.46-fold respectively. Plasmodium falciparum and P. malariae infection are the prevailing species in the study area; albeit varying from the national average. HIV and SCD were not associated with the risk of having malaria.

Real-time polymerase chain reaction assay for the rapid detection and characterization of chloroquine-resistant Plasmodium falciparum malaria in returned travelers.

PubMed

Farcas, Gabriella A; Soeller, Rainer; Zhong, Kathleen; Zahirieh, Alireza; Kain, Kevin C

2006-03-01

Imported drug-resistant malaria is a growing problem in industrialized countries. Rapid and accurate diagnosis is essential to prevent malaria-associated mortality in returned travelers. However, outside of a limited number of specialized centers, the microscopic diagnosis of malaria is slow, unreliable, and provides little information about drug resistance. Molecular diagnostics have the potential to overcome these limitations. We developed and evaluated a rapid, real-time polymerase chain reaction (PCR) assay to detect Plasmodium falciparum malaria and chloroquine (CQ)-resistance determinants in returned travelers who are febrile. A real-time PCR assay based on detection of the K76T mutation in PfCRT (K76T) of P. falciparum was developed on a LightCycler platform (Roche). The performance characteristics of the real-time assay were compared with those of the nested PCR-restriction fragment-length polymorphism (RFLP) and the sequence analyses of samples obtained from 200 febrile returned travelers, who included 125 infected with P. falciparum (48 of whom were infected CQ-susceptible [K76] and 77 of whom were CQ-resistant [T76] P. falciparum), 22 infected with Plasmodium vivax, 10 infected with Plasmodium ovale, 3 infected with Plasmodium malariae malaria, and 40 infected with other febrile syndromes. All patient samples were coded, and all analyses were performed blindly. The real-time PCR assay detected multiple pfcrt haplotypes associated with CQ resistance in geographically diverse malaria isolates acquired by travelers. Compared with nested-PCR RFLP (the reference standard), the real-time assay was 100% sensitive and 96.2% specific for detection of the P. falciparum K76T mutation. This assay is rapid, sensitive, and specific for the detection and characterization of CQ-resistant P. falciparum malaria in returned travelers. This assay is automated, standardized, and suitable for routine use in clinical diagnostic laboratories.

Flow Cytometry Based Detection and Isolation of Plasmodium falciparum Liver Stages In Vitro.

PubMed

Dumoulin, Peter C; Trop, Stefanie A; Ma, Jinxia; Zhang, Hao; Sherman, Matthew A; Levitskaya, Jelena

2015-01-01

Malaria, the disease caused by Plasmodium parasites, remains a major global health burden. The liver stage of Plasmodium falciparum infection is a leading target for immunological and pharmacological interventions. Therefore, novel approaches providing specific detection and isolation of live P. falciparum exoerythrocytic forms (EEFs) are warranted. Utilizing a recently generated parasite strain expressing green fluorescent protein (GFP) we established a method which, allows for detection and isolation of developing live P. falciparum liver stages by flow cytometry. Using this technique we compared the susceptibility of five immortalized human hepatocyte cell lines and primary hepatocyte cultures from three donors to infection by P. falciparum sporozoites. Here, we show that EEFs can be detected and isolated from in vitro infected cultures of the HC-04 cell line and primary human hepatocytes. We confirmed the presence of developing parasites in sorted live human hepatocytes and characterized their morphology by fluorescence microscopy. Finally, we validated the practical applications of our approach by re-examining the importance of host ligand CD81 for hepatocyte infection by P. falciparum sporozoites in vitro and assessment of the inhibitory activity of anti-sporozoite antibodies. This methodology provides us with the tools to study both, the basic biology of the P. falciparum liver stage and the effects of host-derived factors on the development of P. falciparum EEFs.

Flow Cytometry Based Detection and Isolation of Plasmodium falciparum Liver Stages In Vitro

PubMed Central

Dumoulin, Peter C.; Trop, Stefanie A.; Ma, Jinxia; Zhang, Hao; Sherman, Matthew A.; Levitskaya, Jelena

2015-01-01

Malaria, the disease caused by Plasmodium parasites, remains a major global health burden. The liver stage of Plasmodium falciparum infection is a leading target for immunological and pharmacological interventions. Therefore, novel approaches providing specific detection and isolation of live P. falciparum exoerythrocytic forms (EEFs) are warranted. Utilizing a recently generated parasite strain expressing green fluorescent protein (GFP) we established a method which, allows for detection and isolation of developing live P. falciparum liver stages by flow cytometry. Using this technique we compared the susceptibility of five immortalized human hepatocyte cell lines and primary hepatocyte cultures from three donors to infection by P. falciparum sporozoites. Here, we show that EEFs can be detected and isolated from in vitro infected cultures of the HC-04 cell line and primary human hepatocytes. We confirmed the presence of developing parasites in sorted live human hepatocytes and characterized their morphology by fluorescence microscopy. Finally, we validated the practical applications of our approach by re-examining the importance of host ligand CD81 for hepatocyte infection by P. falciparum sporozoites in vitro and assessment of the inhibitory activity of anti-sporozoite antibodies. This methodology provides us with the tools to study both, the basic biology of the P. falciparum liver stage and the effects of host-derived factors on the development of P. falciparum EEFs. PMID:26070149

Evaluation of wondfo rapid diagnostic kit (Pf-HRP2/PAN-pLDH) for diagnosis of malaria by using nano-gold immunochromatographic assay.

PubMed

Wu, Junlin; Peng, Yunping; Liu, Xiaoyun; Li, Wenmei; Tang, Shixing

2014-06-01

Prompt and accurate diagnosis is necessary to start adequate treatment for different affecting species including P. falciparum and P. vivax. Here we described the Wondfo Rapid diagnostic Kit (Pf-HRP2/PAN-pLDH) for the detection of P. falciparum and pan-plasmodium in patient specimen by using a nano-gold immunochromatographic assay. Our rapid assay adapted nano-gold labeling techniques and the monoclonal antibodies (mAbs) against both histidine rich protein-2 (Pf HRP-2) of P. falciparum and pan plasmodium-specific pLDH (pan pLDH). The established two-antibody sandwich immunochromatographic assay could detect P. falciparum and pan-plasmodium. The sensitivity and specificity of Wondfo rapid diagnostic kit were determined by comparing with the "gold standard" of microscopic examination of blood smears. In this study1023 blood samples were collected from outpatient clinics in China and Burma, and detected by both Wondfo kit and microscopic examination. The detection sensitivity and specificity of Wondfo rapid diagnostic kit were 96.46% and 99.67% for P. falciparum (HRP2), 95.03% and 99.24% for pLDH, 96.83% and 99.74% for non-falciparum species, 96.70% and 99.74% for P. vivax, respectively. These results indicate that Wondfo rapid diagnostic assay may be useful for detecting P. falciparum and non-P. falciparum (especially P.v.) in patient specimen.

Single low-dose primaquine for blocking transmission of Plasmodium falciparum malaria - a proposed model-derived age-based regimen for sub-Saharan Africa.

PubMed

Taylor, W Robert; Naw, Htee Khu; Maitland, Kathryn; Williams, Thomas N; Kapulu, Melissa; D'Alessandro, Umberto; Berkley, James A; Bejon, Philip; Okebe, Joseph; Achan, Jane; Amambua, Alfred Ngwa; Affara, Muna; Nwakanma, Davis; van Geertruyden, Jean-Pierre; Mavoko, Muhindo; Lutumba, Pascal; Matangila, Junior; Brasseur, Philipe; Piola, Patrice; Randremanana, Rindra; Lasry, Estrella; Fanello, Caterina; Onyamboko, Marie; Schramm, Birgit; Yah, Zolia; Jones, Joel; Fairhurst, Rick M; Diakite, Mahamadou; Malenga, Grace; Molyneux, Malcolm; Rwagacondo, Claude; Obonyo, Charles; Gadisa, Endalamaw; Aseffa, Abraham; Loolpapit, Mores; Henry, Marie-Claire; Dorsey, Grant; John, Chandy; Sirima, Sodiomon B; Barnes, Karen I; Kremsner, Peter; Day, Nicholas P; White, Nicholas J; Mukaka, Mavuto

2018-01-18

In 2012, the World Health Organization recommended blocking the transmission of Plasmodium falciparum with single low-dose primaquine (SLDPQ, target dose 0.25 mg base/kg body weight), without testing for glucose-6-phosphate dehydrogenase deficiency (G6PDd), when treating patients with uncomplicated falciparum malaria. We sought to develop an age-based SLDPQ regimen that would be suitable for sub-Saharan Africa. Using data on the anti-infectivity efficacy and tolerability of primaquine (PQ), the epidemiology of anaemia, and the risks of PQ-induced acute haemolytic anaemia (AHA) and clinically significant anaemia (CSA), we prospectively defined therapeutic-dose ranges of 0.15-0.4 mg PQ base/kg for children aged 1-5 years and 0.15-0.5 mg PQ base/kg for individuals aged ≥6 years (therapeutic indices 2.7 and 3.3, respectively). We chose 1.25 mg PQ base for infants aged 6-11 months because they have the highest rate of baseline anaemia and the highest risks of AHA and CSA. We modelled an anthropometric database of 661,979 African individuals aged ≥6 months (549,127 healthy individuals, 28,466 malaria patients and 84,386 individuals with other infections/illnesses) by the Box-Cox transformation power exponential and tested PQ doses of 1-15 mg base, selecting dosing groups based on calculated mg/kg PQ doses. From the Box-Cox transformation power exponential model, five age categories were selected: (i) 6-11 months (n = 39,886, 6.03%), (ii) 1-5 years (n = 261,036, 45.46%), (iii) 6-9 years (n = 20,770, 3.14%), (iv) 10-14 years (n = 12,155, 1.84%) and (v) ≥15 years (n = 328,132, 49.57%) to receive 1.25, 2.5, 5, 7.5 and 15 mg PQ base for corresponding median (1st and 99th centiles) mg/kg PQ base of: (i) 0.16 (0.12-0.25), (ii) 0.21 (0.13-0.37), (iii) 0.25 (0.16-0.38), (iv) 0.26 (0.15-0.38) and (v) 0.27 (0.17-0.40). The proportions of individuals predicted to receive optimal therapeutic PQ doses were: 73.2 (29,180/39,886), 93.7 (244,537/261,036), 99.6 (20,690/20,770), 99.4 (12,086/12,155) and 99.8% (327,620/328,132), respectively. We plan to test the safety of this age-based dosing regimen in a large randomised placebo-controlled trial (ISRCTN11594437) of uncomplicated falciparum malaria in G6PDd African children aged 0.5 - 11 years. If the regimen is safe and demonstrates adequate pharmacokinetics, it should be used to support malaria elimination.

Piperaquine Resistance in Plasmodium falciparum, West Africa.

PubMed

Inoue, Juliana; Silva, Miguel; Fofana, Bakary; Sanogo, Kassim; Mårtensson, Andreas; Sagara, Issaka; Björkman, Anders; Veiga, Maria Isabel; Ferreira, Pedro Eduardo; Djimde, Abdoulaye; Gil, José Pedro

2018-08-17

Dihydroartemisinin/piperaquine (DHA/PPQ) is increasingly deployed as antimalaria drug in Africa. We report the detection in Mali of Plasmodium falciparum infections carrying plasmepsin 2 duplications (associated with piperaquine resistance) in 7/65 recurrent infections within 2 months after DHA/PPQ treatment. These findings raise concerns about the long-term efficacy of DHA/PPQ treatment in Africa.

Cinnamic acid/chloroquinoline conjugates as potent agents against chloroquine-resistant Plasmodium falciparum.

PubMed

Pérez, Bianca; Teixeira, Cátia; Gut, Jiri; Rosenthal, Philip J; Gomes, José R B; Gomes, Paula

2012-09-01

Cinnamic acid derivatives containing a 4-amino-7-chloroquinoline scaffold (blue) and substituted cinnamoyl building blocks (green) linked through an alkylamine chain (red) were found to have potent (11-59 nM) in vitro activities against erythrocytic chloroquine- resistant Plasmodium falciparum. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gametocyte clearance dynamics following oral artesunate treatment of uncomplicated falciparum malaria in Malian children.

PubMed

Djimde, Abdoulaye A; Maiga, Amelia W; Ouologuem, Dinkorma; Fofana, Bakary; Sagara, Issaka; Dembele, Demba; Toure, Sekou; Sanogo, Kassim; Dama, Souleymane; Sidibe, Bakary; Doumbo, Ogobara K

2016-01-01

Artemisinin-based combination therapies decrease Plasmodium gametocyte carriage. However, the role of artesunate in monotherapy in vivo, the mechanisms involved, and the utility of gametocyte carriage as a potential tool for the surveillance of antimalarial resistance are poorly understood. In 2010-2011, we conducted an open-label, prospective efficacy study of artesunate as monotherapy in children 1-10 years of age with uncomplicated falciparum malaria in Bougoula-Hameau, Mali. Standard oral doses of artesunate were administered for 7 days and patients were followed up for 28 days. The data were compared to a similar study conducted in 2002-2004. Of 100 children enrolled in the 2010-2011 study, 92 were analyzed and compared to 217 children enrolled in the 2002-2004 study. The proportion of gametocyte carriers was unchanged at the end of treatment (23% at baseline vs. 24% on day 7, p = 1.0) and did not significantly decline until day 21 of follow-up (23% vs. 6%, p = 0.003). The mean gametocyte density at inclusion remained unchanged at the end of treatment (12 gametocytes/μL vs. 16 gametocytes/μL, p = 0.6). Overall, 46% of the 71 initial non-carriers had gametocytes detected by day 7. Similar results were found in the 2002-2004 study. In both studies, although gametocyte carriage significantly decreased by the end of the 28-day follow-up, artesunate did not clear mature gametocytes during treatment and did not prevent the appearance of new stage V gametocytes as assessed by light microscopy. Baseline gametocyte carriage was significantly higher 6 years after the deployment of artemisinin-based combination therapies in this setting. © A.A. Djimde et al., published by EDP Sciences, 2016.

The Plasmodium falciparum chloroquine resistance transporter is associated with the ex vivo P. falciparum African parasite response to pyronaridine.

PubMed

Madamet, Marylin; Briolant, Sébastien; Amalvict, Rémy; Benoit, Nicolas; Bouchiba, Housem; Cren, Julien; Pradines, Bruno

2016-02-09

The pyronaridine-artesunate combination is one of the most recent oral artemisinin-based therapeutic combinations (ACTs) recommended for the treatment of uncomplicated P. falciparum malaria. The emergence of P. falciparum resistance to artemisinin has recently developed in Southeast Asia. Little data are available on the association between pyronaridine susceptibility and polymorphisms in genes involved in antimalarial drug resistance. The objective of the present study was to investigate the association between ex vivo responses to pyronaridine and the K76T mutation in the pfcrt gene in P. falciparum isolates. The assessment of ex vivo susceptibility to pyronaridine was performed on 296 P. falciparum isolates using a standard 42-h 3H-hypoxanthine uptake inhibition method. The K76T mutation was also investigated. The pyronaridine IC50 (inhibitory concentration 50 %) ranged from 0.55 to 80.0 nM. Ex vivo responses to pyronaridine were significantly associated with the K76T mutation (p-value = 0.020). The reduced susceptibility to pyronaridine, defined as IC50 > 60 nM, was significantly associated with the K76T mutation (p-value = 0.004). Using a Bayesian mixture modelling approach, the pyronaridine IC50 were classified into three components: component A (IC50 median 15.9 nM), component B (IC50 median 34.2 nM) and component C (IC50 median 63.3 nM). The K76T mutation was represented in 46.3% of the isolates in component A, 47.2% of the isolates in component B and 73.3% of the isolates in component C (p-value = 0.021). These results showed the ex vivo reduced susceptibility to pyronaridine, i.e., IC50 > 60 nM, associated with the K76T mutation.

High Rates of Asymptomatic, Sub-microscopic Plasmodium vivax Infection and Disappearing Plasmodium falciparum Malaria in an Area of Low Transmission in Solomon Islands.

PubMed

Waltmann, Andreea; Darcy, Andrew W; Harris, Ivor; Koepfli, Cristian; Lodo, John; Vahi, Ventis; Piziki, David; Shanks, G Dennis; Barry, Alyssa E; Whittaker, Maxine; Kazura, James W; Mueller, Ivo

2015-05-01

Solomon Islands is intensifying national efforts to achieve malaria elimination. A long history of indoor spraying with residual insecticides, combined recently with distribution of long lasting insecticidal nets and artemether-lumefantrine therapy, has been implemented in Solomon Islands. The impact of these interventions on local endemicity of Plasmodium spp. is unknown. In 2012, a cross-sectional survey of 3501 residents of all ages was conducted in Ngella, Central Islands Province, Solomon Islands. Prevalence of Plasmodium falciparum, P. vivax, P. ovale and P. malariae was assessed by quantitative PCR (qPCR) and light microscopy (LM). Presence of gametocytes was determined by reverse transcription quantitative PCR (RT-qPCR). By qPCR, 468 Plasmodium spp. infections were detected (prevalence = 13.4%; 463 P. vivax, five mixed P. falciparum/P. vivax, no P. ovale or P. malariae) versus 130 by LM (prevalence = 3.7%; 126 P. vivax, three P. falciparum and one P. falciparum/P. vivax). The prevalence of P. vivax infection varied significantly among villages (range 3.0-38.5%, p<0.001) and across age groups (5.3-25.9%, p<0.001). Of 468 P. vivax infections, 72.9% were sub-microscopic, 84.5% afebrile and 60.0% were both sub-microscopic and afebrile. Local residency, low education level of the household head and living in a household with at least one other P. vivax infected individual increased the risk of P. vivax infection. Overall, 23.5% of P. vivax infections had concurrent gametocytaemia. Of all P. vivax positive samples, 29.2% were polyclonal by MS16 and msp1F3 genotyping. All five P. falciparum infections were detected in residents of the same village, carried the same msp2 allele and four were positive for P. falciparum gametocytes. P. vivax infection remains endemic in Ngella, with the majority of cases afebrile and below the detection limit of LM. P. falciparum has nearly disappeared, but the risk of re-introductions and outbreaks due to travel to nearby islands with higher malaria endemicity remains.

Antibodies elicited during natural infection in a predominantly Plasmodium falciparum transmission area cross-react with sexual stage-specific antigen in P. vivax.

PubMed

Bansal, Geetha P; Vengesai, Arthur; Cao, Yi; Mduluza, Takafira; Kumar, Nirbhay

2017-06-01

Infections caused by Plasmodium falciparum and P. vivax account for more than 90% of global malaria burden. Exposure to malaria parasite elicits immune responses during natural infection and it is generally believed that the immunity is not only stage specific but also species specific. However, partial genomic similarity for various antigens in different Plasmodium spp. raises the possibility of immunological cross-reactivity at the level of specific antigens. Serum samples collected from children who were permanent residents of a P. falciparum transmission area in Zimbabwe were screened for antibody reactivity against Pfs48/45, a P. falciparum gametocyte antigen and Pvs48/45, a P. vivax homolog of Pfs48/45 using ELISA. Western blotting was used to further confirm identity of the specific antibody reactivity to the Pfs48/45 and Pvs48/45 proteins. Pan Plasmodium PCR and nested PCR were used to confirm infection with the Plasmodium species. Twenty-seven percent (49/181) of the participants were found to be sero-positive for Pfs48/45 and 73% (n=36) of these Pfs48/45 positive sera also showed reactivity with Pvs48/45. Immune cross-reactivity revealed by ELISA was also confirmed by Western blot analysis using a panel of randomly selected 23 Pfs48/45 and Pvs48/45 ELISA positive samples. Nested PCR analysis of 27 blood samples randomly selected from the 36 that showed positive ELISA reactivity to both Pfs48/45 and Pvs48/45 antigens confirmed infection with P. falciparum and generalized absence of P. vivax except for a single sample which revealed PCR positivity for both P. vivax and P. falciparum. Our studies with sera samples from a predominantly P. falciparum transmission area in Zimbabwe suggest immunological cross-reactivity with Pvs48/45, thus raising the possibility of partial species cross-reactive immunity and possible cross-boosting of immunity during co-infection with P. falciparum and P. vivax. Copyright © 2017 Elsevier B.V. All rights reserved.

High Rates of Asymptomatic, Sub-microscopic Plasmodium vivax Infection and Disappearing Plasmodium falciparum Malaria in an Area of Low Transmission in Solomon Islands

PubMed Central

Waltmann, Andreea; Darcy, Andrew W.; Harris, Ivor; Koepfli, Cristian; Lodo, John; Vahi, Ventis; Piziki, David; Shanks, G. Dennis; Barry, Alyssa E.; Whittaker, Maxine; Kazura, James W.; Mueller, Ivo

2015-01-01

Introduction Solomon Islands is intensifying national efforts to achieve malaria elimination. A long history of indoor spraying with residual insecticides, combined recently with distribution of long lasting insecticidal nets and artemether-lumefantrine therapy, has been implemented in Solomon Islands. The impact of these interventions on local endemicity of Plasmodium spp. is unknown. Methods In 2012, a cross-sectional survey of 3501 residents of all ages was conducted in Ngella, Central Islands Province, Solomon Islands. Prevalence of Plasmodium falciparum, P. vivax, P. ovale and P. malariae was assessed by quantitative PCR (qPCR) and light microscopy (LM). Presence of gametocytes was determined by reverse transcription quantitative PCR (RT-qPCR). Results By qPCR, 468 Plasmodium spp. infections were detected (prevalence = 13.4%; 463 P. vivax, five mixed P. falciparum/P. vivax, no P. ovale or P. malariae) versus 130 by LM (prevalence = 3.7%; 126 P. vivax, three P. falciparum and one P. falciparum/P. vivax). The prevalence of P. vivax infection varied significantly among villages (range 3.0–38.5%, p<0.001) and across age groups (5.3–25.9%, p<0.001). Of 468 P. vivax infections, 72.9% were sub-microscopic, 84.5% afebrile and 60.0% were both sub-microscopic and afebrile. Local residency, low education level of the household head and living in a household with at least one other P. vivax infected individual increased the risk of P. vivax infection. Overall, 23.5% of P. vivax infections had concurrent gametocytaemia. Of all P. vivax positive samples, 29.2% were polyclonal by MS16 and msp1F3 genotyping. All five P. falciparum infections were detected in residents of the same village, carried the same msp2 allele and four were positive for P. falciparum gametocytes. Conclusion P. vivax infection remains endemic in Ngella, with the majority of cases afebrile and below the detection limit of LM. P. falciparum has nearly disappeared, but the risk of re-introductions and outbreaks due to travel to nearby islands with higher malaria endemicity remains. PMID:25996619

Cultivation of Plasmodium falciparum parasites in a serum-free medium.

PubMed

Ofulla, A V; Okoye, V C; Khan, B; Githure, J I; Roberts, C R; Johnson, A J; Martin, S K

1993-09-01

The elimination of serum from Plasmodium falciparum culture media could decrease costs, enhance procurement, and improve the feasibility of large-scale production of parasite material. We provide a semi-defined, serum-free formulation, of commercially available constituents that supports P. falciparum parasite growth at rates comparable with those obtained with serum-supplemented media. The medium is composed of RPMI 1640 to which HEPES, extra glucose, bicarbonate, and hypoxanthine have been added. Bovine albumin and serum-derived, lipids-cholesterol-rich mixture are then used in place of serum.

Asymptomatic Plasmodium Infections in Children in Low Malaria Transmission Setting, Southwestern Uganda(1).

PubMed

Roh, Michelle E; Oyet, Caesar; Orikiriza, Patrick; Wade, Martina; Kiwanuka, Gertrude N; Mwanga-Amumpaire, Juliet; Parikh, Sunil; Boum, Yap

2016-08-01

A survey of asymptomatic children in Uganda showed Plasmodium malariae and P. falciparum parasites in 45% and 55% of microscopy-positive samples, respectively. Although 36% of microscopy-positive samples were negative by rapid diagnostic test, 75% showed P. malariae or P. ovale parasites by PCR, indicating that routine diagnostic testing misses many non-P. falciparum malarial infections.

Electron Microscopy to Correlate Cell Structure and Biochemical Activity

DTIC Science & Technology

1993-03-10

prevent and/or cure cerebral malaria. d) Morphological effects of artemisinin in Plasmodium falciparum In collaboration with Dr. Milhous of WRAR...uitrastructural changes induced in jPlasmodium falciparum, by artemisinin were studied in vitro. Two hours after administration, changes were...Electron microscope autoradiography was performed after [5H]-dihydroartemisinin and [uC]- artemisinin were administered to infected erythrocytes in

Molecular Surveillance for Multidrug-Resistant Plasmodium falciparum, Cambodia

PubMed Central

Shah, Naman K.; Alker, Alisa P.; Sem, Rithy; Susanti, Agustina Ika; Muth, Sinuon; Maguire, Jason D.; Duong, Socheat; Ariey, Frederic; Meshnick, Steven R.

2008-01-01

We conducted surveillance for multidrug-resistant Plasmodium falciparum in Cambodia during 2004–2006 by assessing molecular changes in pfmdr1. The high prevalence of isolates with multiple pfmdr1 copies found in western Cambodia near the Thai border, where artesunate–mefloquine therapy failures occur, contrasts with isolates from eastern Cambodia, where this combination therapy remains highly effective. PMID:18826834

The Plasmodium falciparum Sexual Development Transcriptome: A Microarray Analysis using Ontology-Based Pattern Identification

DTIC Science & Technology

2005-06-17

ciparum. Mol Biochem Parasitol 1992;56(2):239–50. [56] Vinetz JM, Dave SK, Specht CA, et al. The chitinase PfCHT1 from the human malaria parasite Plasmodium...falciparum lacks proenzyme and chitin -binding domains and displays unique substrate prefer- ences. Proc Natl Acad Sci USA 1999;96(24):14061–6. [57

An analysis of mobile genetic elements in three Plasmodium species and their potential impact on the nucleotide composition of the P. falciparum genome.

PubMed

Durand, Pierre M; Oelofse, Andries J; Coetzer, Theresa L

2006-11-04

The completed genome sequences of the malaria parasites P. falciparum, P. y. yoelii and P. vivax have revealed some unusual features. P. falciparum contains the most AT rich genome sequenced so far--over 90% in some regions. In comparison, P. y. yoelii is approximately 77% and P. vivax is approximately 55% AT rich. The evolutionary reasons for these findings are unknown. Mobile genetic elements have a considerable impact on genome evolution but a thorough investigation of these elements in Plasmodium has not been undertaken. We therefore performed a comprehensive genome analysis of these elements and their derivatives in the three Plasmodium species. Whole genome analysis was performed using bioinformatic methods. Forty potential protein encoding sequences with features of transposable elements were identified in P. vivax, eight in P. y. yoelii and only six in P. falciparum. Further investigation of the six open reading frames in P. falciparum revealed that only one is potentially an active mobile genetic element. Most of the open reading frames identified in all three species are hypothetical proteins. Some represent annotated host proteins such as the putative telomerase reverse transcriptase genes in P. y. yoelii and P. falciparum. One of the P. vivax open reading frames identified in this study demonstrates similarity to telomerase reverse transcriptase and we conclude it to be the orthologue of this gene. There is a divergence in the frequencies of mobile genetic elements in the three Plasmodium species investigated. Despite the limitations of whole genome analytical methods, it is tempting to speculate that mobile genetic elements might have been a driving force behind the compositional bias of the P. falciparum genome.

Functional Antibodies against VAR2CSA in Nonpregnant Populations from Colombia Exposed to Plasmodium falciparum and Plasmodium vivax

PubMed Central

Doritchamou, Justin; Arango, Eliana M.; Cabrera, Ana; Arroyo, Maria Isabel; Kain, Kevin C.; Ndam, Nicaise Tuikue; Maestre, Amanda

2014-01-01

In pregnancy, parity-dependent immunity is observed in response to placental infection with Plasmodium falciparum. Antibodies recognize the surface antigen, VAR2CSA, expressed on infected red blood cells and inhibit cytoadherence to the placental tissue. In most settings of malaria endemicity, antibodies against VAR2CSA are predominantly observed in multigravid women and infrequently in men, children, and nulligravid women. However, in Colombia, we detected antibodies against multiple constructs of VAR2CSA among men and children with acute P. falciparum and Plasmodium vivax infection. The majority of men and children (>60%) had high levels of IgGs against three recombinant domains of VAR2CSA: DBL5ε, DBL3X, and ID1-ID2. Surprisingly, these antibodies were observed only in pregnant women, men, and children exposed either to P. falciparum or to P. vivax. Moreover, the anti-VAR2CSA antibodies are of high avidity and efficiently inhibit adherence of infected red blood cells to chondroitin sulfate A in vitro, suggesting that they are specific and functional. These unexpected results suggest that there may be genotypic or phenotypic differences in the parasites of this region or in the host response to either P. falciparum or P. vivax infection outside pregnancy. These findings may hold significant clinical relevance to the pathophysiology and outcome of malaria infections in this region. PMID:24686068

Pernicious plans revealed: Plasmodium falciparum genome wide expression analysis.

PubMed

Llinás, Manuel; DeRisi, Joseph L

2004-08-01

The asexual intraerythrocytic developmental cycle (IDC) of Plasmodium falciparum is responsible for the majority of the clinical manifestations of malaria in humans. Although malaria has been studied for over a century, the elucidation of the full genome sequence of P. falciparum has now allowed for in-depth studies of gene expression throughout the entire intraerythrocytic stage. As the mainstays of anti-malarial chemotherapy become increasingly ineffective, we need a deeper understanding of fundamental plasmodial bioregulatory mechanisms to successfully subvert them. Recent gene expression studies have begun to examine different aspects of the IDC and are providing key insights into the basic mechanisms of Plasmodium gene regulation and are helping to define gene functions. However, to date, no transcription factor has been fully characterized from Plasmodium and the definitive identification of cis-acting regulatory elements along with their corresponding trans-acting partners is still lacking. The characterization of the transcriptome of P. falciparum is the first major step towards the understanding of the genome wide regulation of gene expression in this parasite. IDC expression data for almost every gene in the P. falciparum genome can now be publicly queried at and. The results of these studies suggest promising leads for identifying novel targets for anti-malarial therapeutics and vaccines in addition to providing a solid foundation for the ongoing elucidation of plasmodial gene expression.

Molecular evidence of high rates of asymptomatic P. vivax infection and very low P. falciparum malaria in Botswana.

PubMed

Motshoge, Thato; Ababio, Grace K; Aleksenko, Larysa; Read, John; Peloewetse, Elias; Loeto, Mazhani; Mosweunyane, Tjantilili; Moakofhi, Kentse; Ntebele, Davies S; Chihanga, Simon; Motlaleng, Mpho; Chinorumba, Anderson; Vurayai, Moses; Pernica, Jeffrey M; Paganotti, Giacomo M; Quaye, Isaac K

2016-09-29

Botswana is one of eight SADC countries targeting malaria elimination by 2018. Through spirited upscaling of control activities and passive surveillance, significant reductions in case incidence of Plasmodium falciparum (0.96 - 0.01) was achieved between 2008 and 2012. As part of the elimination campaign, active detection of asymptomatic Plasmodium species by a highly sensitive method was deemed necessary. This study was carried out to determine asymptomatic Plasmodium species carriage by nested PCR in the country, in 2012. A cross-sectional study involving 3924 apparently healthy participants were screened for Plasmodium species in 14 districts (5 endemic: Okavango, Ngami, Tutume, Boteti and Bobirwa; and 9 epidemic: North East, Francistown, Serowe-Palapye, Ghanzi, Kweneng West, Kweneng East, Kgatleng, South East, and Good Hope). Venous blood was taken from each participant for a nested PCR detection of Plasmodium species. The parasite rates of asymptomatic Plasmodium species detected were as follows: Plasmodium falciparum, 0.16 %; Plasmodium vivax, 4.66 %; Plasmodium malariae, (Pm) 0.16 %; Plasmodium ovale, 0 %, mixed infections (P. falciparum and P. vivax), 0.055 %; and (P. vivax and P. malariae), 0.027 %, (total: 5.062 %). The high proportion of asymptomatic reservoir of P. vivax was clustered in the East, South Eastern and Central districts of the country. There appeared to be a correlation between the occurrence of P. malariae infection with P. vivax infection, with the former only occurring in districts that had substantial P. vivax circulation. The median age among 2-12 year olds for P. vivax infection was 5 years (Mean 5.13 years, interquartile range 3-7 years). The odds of being infected with P. vivax decreased by 7 % for each year increase in age (OR 0.93, 95 % CI 0.87-1.00, p = 0.056). We have confirmed low parasite rate of asymptomatic Plasmodium species in Botswana, with the exception of P.vivax which was unexpectedly high. This has implication for the elimination campaign so a follow up study is warranted to inform decisions on new strategies that take this evidence into account in the elimination campaign.

The epidemiology of Plasmodium vivax and Plasmodium falciparum malaria in China, 2004-2012: from intensified control to elimination.

PubMed

Zhang, Qian; Lai, Shengjie; Zheng, Canjun; Zhang, Honglong; Zhou, Sheng; Hu, Wenbiao; Clements, Archie C A; Zhou, Xiao-Nong; Yang, Weizhong; Hay, Simon I; Yu, Hongjie; Li, Zhongjie

2014-11-03

In China, the national malaria elimination programme has been operating since 2010. This study aimed to explore the epidemiological changes in patterns of malaria in China from intensified control to elimination stages. Data on nationwide malaria cases from 2004 to 2012 were extracted from the Chinese national malaria surveillance system. The secular trend, gender and age features, seasonality, and spatial distribution by Plasmodium species were analysed. In total, 238,443 malaria cases were reported, and the proportion of Plasmodium falciparum increased drastically from <10% before 2010 to 55.2% in 2012. From 2004 to 2006, malaria showed a significantly increasing trend and with the highest incidence peak in 2006 (4.6/100,000), while from 2007 onwards, malaria decreased sharply to only 0.18/100,000 in 2012. Males and young age groups became the predominantly affected population. The areas affected by Plasmodium vivax malaria shrunk, while areas affected by P. falciparum malaria expanded from 294 counties in 2004 to 600 counties in 2012. This study demonstrated that malaria has decreased dramatically in the last five years, especially since the Chinese government launched a malaria elimination programme in 2010, and areas with reported falciparum malaria cases have expanded over recent years. These findings suggest that elimination efforts should be improved to meet these changes, so as to achieve the nationwide malaria elimination goal in China in 2020.

Modeling the inhibition of quadruple mutant Plasmodium falciparum dihydrofolate reductase by pyrimethamine derivatives

NASA Astrophysics Data System (ADS)

Fogel, Gary B.; Cheung, Mars; Pittman, Eric; Hecht, David

2008-01-01

Modeling studies were performed on known inhibitors of the quadruple mutant Plasmodium falciparum dihydrofolate reductase (DHFR). GOLD was used to dock 32 pyrimethamine derivatives into the active site of DHFR obtained from the x-ray crystal structure 1J3K.pdb. Several scoring functions were evaluated and the Molegro Protein-Ligand Interaction Score was determined to have one of the best correlation to experimental p K i . In conjunction with Protein-Ligand Interaction scores, predicted binding modes and key protein-ligand interactions were evaluated and analyzed in order to develop criteria for selecting compounds having a greater chance of activity versus resistant strains of Plasmodium falciparum. This methodology will be used in future studies for selection of compounds for focused screening libraries.

Imported Plasmodium falciparum and locally transmitted Plasmodium vivax: cross-border malaria transmission scenario in northwestern Thailand.

PubMed

Sriwichai, Patchara; Karl, Stephan; Samung, Yudthana; Kiattibutr, Kirakorn; Sirichaisinthop, Jeeraphat; Mueller, Ivo; Cui, Liwang; Sattabongkot, Jetsumon

2017-06-21

Cross-border malaria transmission is an important problem for national malaria control programmes. The epidemiology of cross-border malaria is further complicated in areas where Plasmodium falciparum and Plasmodium vivax are both endemic. By combining passive case detection data with entomological data, a transmission scenario on the northwestern Thai-Myanmar border where P. falciparum is likely driven by importation was described, whereas P. vivax is also locally transmitted. This study highlights the differences in the level of control required to eliminate P. falciparum and P. vivax from the same region. Malaria case data were collected from malaria clinics in Suan Oi village, Tak Province, Thailand between 2011 and 2014. Infections were diagnosed by light microscopy. Demographic data, including migrant status, were correlated with concomitantly collected entomology data from 1330 mosquito trap nights using logistic regression. Malaria infection in the captured mosquitoes was detected by ELISA. Recent migrants were almost four times more likely to be infected with P. falciparum compared with Thai patients (OR 3.84, p < 0.001) and cases were significantly associated with seasonal migration. However, P. falciparum infection was not associated with the Anopheles mosquito capture rates, suggesting predominantly imported infections. In contrast, recent migrants were equally likely to present with P. vivax as mid-term migrants. Both migrant groups were twice as likely to be infected with P. vivax in comparison to the resident Thai population (OR 1.96, p < 0.001 and OR 1.94, p < 0.001, respectively). Plasmodium vivax cases were strongly correlated with age and local capture rates of two major vector species Anopheles minimus and Anopheles maculatus (OR 1.23, p = 0.020 and OR 1.33, p = 0.046, respectively), suggesting that a high level of local transmission might be causing these infections. On the Thai-Myanmar border, P. falciparum infections occur mostly in the recent migrant population with a seasonality reflecting that of agricultural activity, rather than that of the local mosquito population. This suggests that P. falciparum was mostly imported. In contrast, P. vivax cases were significantly associated with mosquito capture rates and less with migrant status, indicating local transmission. This highlights the different timelines and requirements for P. falciparum and P. vivax elimination in the same region and underlines the importance of multinational, cross-border malaria control.

Fatty Acid Synthesis and Pyruvate Metabolism Pathways Remain Active in Dihydroartemisinin-Induced Dormant Ring Stages of Plasmodium falciparum

PubMed Central

Chen, Nanhua; LaCrue, Alexis N.; Teuscher, Franka; Waters, Norman C.; Gatton, Michelle L.; Kyle, Dennis E.

2014-01-01

Artemisinin (ART)-based combination therapy (ACT) is used as the first-line treatment of uncomplicated falciparum malaria worldwide. However, despite high potency and rapid action, there is a high rate of recrudescence associated with ART monotherapy or ACT long before the recent emergence of ART resistance. ART-induced ring-stage dormancy and recovery have been implicated as possible causes of recrudescence; however, little is known about the characteristics of dormant parasites, including whether dormant parasites are metabolically active. We investigated the transcription of 12 genes encoding key enzymes in various metabolic pathways in P. falciparum during dihydroartemisinin (DHA)-induced dormancy and recovery. Transcription analysis showed an immediate downregulation for 10 genes following exposure to DHA but continued transcription of 2 genes encoding apicoplast and mitochondrial proteins. Transcription of several additional genes encoding apicoplast and mitochondrial proteins, particularly of genes encoding enzymes in pyruvate metabolism and fatty acid synthesis pathways, was also maintained. Additions of inhibitors for biotin acetyl-coenzyme A (CoA) carboxylase and enoyl-acyl carrier reductase of the fatty acid synthesis pathways delayed the recovery of dormant parasites by 6 and 4 days, respectively, following DHA treatment. Our results demonstrate that most metabolic pathways are downregulated in DHA-induced dormant parasites. In contrast, fatty acid and pyruvate metabolic pathways remain active. These findings highlight new targets to interrupt recovery of parasites from ART-induced dormancy and to reduce the rate of recrudescence following ART treatment. PMID:24913167

COMPETITION FOR RED BLOOD CELLS CAN ENHANCE PLASMODIUM VIVAX PARASITEMIA IN MIXED-SPECIES MALARIA INFECTIONS

PubMed Central

MCQUEEN, PHILIP G.; MCKENZIE, F. ELLIS

2008-01-01

We assess the consequences of competition for red blood cells (RBCs) in co-infections with the two major agents of human malaria, Plasmodium vivax and Plasmodium falciparum, using differential equations to model the population dynamics of RBCs and parasites. P. vivax parasitizes only the youngest RBCs, but this can reduce the broader RBC population susceptible to P. falciparum. We found that competition for RBCs typically causes one species to suppress the other, depending on their relative reproduction rates and timing of inoculation. However, if the species’ reproduction rates are nearly equal, transient increases in RBC production stimulated by the presence of P. falciparum may boost P. vivax parasitemia above its single-species infection level. Conversely, P. falciparum parasitemia is rarely enhanced above its single-species level. Furthermore, transients in RBC production can induce coupled oscillations in the parasitemia of both species. These results are remarkably robust to changes in model parameters. PMID:16837717

Absence of association between polymorphisms in the K13 gene and the presence of Plasmodium falciparum parasites at day 3 after treatment with artemisinin derivatives in Senegal.

PubMed

Madamet, Marylin; Kounta, Mame Bou; Wade, Khalifa Ababacar; Lo, Gora; Diawara, Silman; Fall, Mansour; Bercion, Raymond; Nakoulima, Aminata; Fall, Khadidiatou Ba; Benoit, Nicolas; Gueye, Mamadou Wague; Fall, Bécaye; Diatta, Bakary; Pradines, Bruno

2017-06-01

In 2006, the Senegalese National Malaria Control Programme recommended artemisinin-based combination therapy as first-line treatment for uncomplicated malaria. In addition, intravenous (i.v.) injection of artesunate and artemether has gradually replaced quinine for the treatment of severe malaria. Mutations in the propeller domain of the Kelch 13 gene (K13-propeller, PF3D71343700), such as Y493H, R539T, I543T and C580Y, were recently associated with in vivo and in vitro resistance to artemisinin in Southeast Asia. However, these mutations were not identified in Africa. In total, 181 isolates of Plasmodium falciparum from 161 patients from Dakar, Senegal, were collected between August 2015 and January 2016. The K13-propeller gene of the isolates was sequenced. A search for non-synonymous mutations in the propeller region of K13 was performed in the 181 isolates collected from Dakar from 2015 to 2016. Three synonymous mutations were detected (D464D, C469C and R471R). Of 119 patients treated with i.v. artesunate or intramuscular artemether followed by artemether/lumefantrine, 9 patients were still parasitaemic on Day 3. Parasites from these nine patients were wild-type for K13-propeller. None of the polymorphisms known to be involved in artemisinin resistance in Asia were detected. These results suggest that K13 is not the best predictive marker for artemisinin resistance in Africa. More isolates from clinical failure cases or patients with delayed parasite clearance after treatment with artemisinin derivatives are necessary to identify new molecular markers. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Molecular and Pharmacological Determinants of the Therapeutic Response to Artemether-Lumefantrine in Multidrug-Resistant Plasmodium falciparum Malaria

PubMed Central

Price, Ric N.; Uhlemann, Anne-Catrin; van Vugt, Michele; Al Brockman; Hutagalung, Robert; Nair, Shalini; Nash, Denae; Singhasivanon, Pratap; Anderson, Tim J. C.; Krishna, Sanjeev; White, Nicholas J.; Nosten, François

2015-01-01

Background Our study examined the relative contributions of host, pharmacokinetic, and parasitological factors in determining the therapeutic response to artemether-lumefantrine (AL). Methods On the northwest border of Thailand, patients with uncomplicated Plasmodium falciparum malaria were enrolled in prospective studies of AL treatment (4- or 6-dose regimens) and followed up for 42 days. Plasma lumefantrine concentrations were measured by high performance liquid chromatography; malaria parasite pfmdr1 copy number was quantified using a real-time polymerase chain reaction assay (PCR), and in vitro drug susceptibility was tested. Results All treatments resulted in a rapid clinical response and were well tolerated. PCR-corrected failure rates at day 42 were 13% (95% confidence interval [CI], 9.6%–17%) for the 4-dose regimen and 3.2% (95% CI, 1.8%–4.6%) for the 6-dose regimen. Increased pfmdr1 copy number was associated with a 2-fold (95% CI, 1.8–2.4-fold) increase in lumefantrine inhibitory concentration50 (P = .001) and an adjusted hazard ratio for risk of treatment failure following completion of a 4-dose regimen, but not a 6-dose regimen, of 4.0 (95% CI, 1.4–11; P = .008). Patients who had lumefantrine levels below 175 ng/mL on day 7 were more likely to experience recrudescence by day 42 (adjusted hazard ratio, 17; 95% CI, 5.5–53), allowing prediction of treatment failure with 75% sensitivity and 84% specificity. The 6-dose regimen ensured that therapeutic levels were achieved in 91% of treated patients. Conclusions The lumefantrine plasma concentration profile is the main determinant of efficacy of artemether-lumefantrine. Amplification in pfmdr1 determines lumefantrine susceptibility and, therefore, treatment responses when plasma lumefantrine levels are subtherapeutic. PMID:16652314

Molecular and pharmacological determinants of the therapeutic response to artemether-lumefantrine in multidrug-resistant Plasmodium falciparum malaria.

PubMed

Price, Ric N; Uhlemann, Anne-Catrin; van Vugt, Michele; Brockman, Al; Hutagalung, Robert; Nair, Shalini; Nash, Denae; Singhasivanon, Pratap; Anderson, Tim J C; Krishna, Sanjeev; White, Nicholas J; Nosten, François

2006-06-01

Our study examined the relative contributions of host, pharmacokinetic, and parasitological factors in determining the therapeutic response to artemether-lumefantrine (AL). On the northwest border of Thailand, patients with uncomplicated Plasmodium falciparum malaria were enrolled in prospective studies of AL treatment (4- or 6-dose regimens) and followed up for 42 days. Plasma lumefantrine concentrations were measured by high performance liquid chromatography; malaria parasite pfmdr1 copy number was quantified using a real-time polymerase chain reaction assay (PCR), and in vitro drug susceptibility was tested. All treatments resulted in a rapid clinical response and were well tolerated. PCR-corrected failure rates at day 42 were 13% (95% confidence interval [CI], 9.6%-17%) for the 4-dose regimen and 3.2% (95% CI, 1.8%-4.6%) for the 6-dose regimen. Increased pfmdr1 copy number was associated with a 2-fold (95% CI, 1.8-2.4-fold) increase in lumefantrine inhibitory concentration(50) (P=.001) and an adjusted hazard ratio for risk of treatment failure following completion of a 4-dose regimen, but not a 6-dose regimen, of 4.0 (95% CI, 1.4-11; P=.008). Patients who had lumefantrine levels below 175 ng/mL on day 7 were more likely to experience recrudescence by day 42 (adjusted hazard ratio, 17; 95% CI, 5.5-53), allowing prediction of treatment failure with 75% sensitivity and 84% specificity. The 6-dose regimen ensured that therapeutic levels were achieved in 91% of treated patients. The lumefantrine plasma concentration profile is the main determinant of efficacy of artemether-lumefantrine. Amplification in pfmdr1 determines lumefantrine susceptibility and, therefore, treatment responses when plasma lumefantrine levels are subtherapeutic.

A microscale human liver platform that supports the hepatic stages of Plasmodium falciparum and vivax

PubMed Central

March, Sandra; Ng, Shengyong; Velmurugan, Soundarapandian; Galstian, Ani; Shan, Jing; Logan, David; Carpenter, Anne; Thomas, David; Lee Sim, B. Kim; Mota, Maria M.; Hoffman, Stephen L.; Bhatia, Sangeeta N.

2013-01-01

SUMMARY The Plasmodium liver stage is an attractive target for the development of anti-malarial drugs and vaccines, as it provides an opportunity to interrupt the life cycle of the parasite at a critical early stage. However, targeting the liver stage has been difficult. Undoubtedly, a major barrier has been the lack of robust, reliable and reproducible in vitro liver stage cultures. Here, we establish the liver stages for both Plasmodium falciparum and Plasmodium vivax in a microscale human liver platform composed of cryopreserved, micropatterned human primary hepatocytes surrounded by supportive stromal cells. Using this system, we have successfully recapitulated the full liver stage of P. falciparum including the release of infected merozoites and infection of overlaid erythrocytes, and also the establishment of small forms in late liver stages of P. vivax. Finally, we validate the potential of this platform as a tool for medium-throughput anti-malarial drug screening and vaccine development. PMID:23870318

Docking, synthesis and antimalarial activity of novel 4-anilinoquinoline derivatives.

PubMed

Vijayaraghavan, Shilpa; Mahajan, Supriya

2017-04-15

A series of 4-anilinoquinoline triazine derivatives were designed, synthesized and screened for in vivo antimalarial activity against a chloroquine-sensitive strain of Plasmodium berghei. The compounds were further subjected to in vitro antimalarial activity against chloroquine-resistant W2 strain of Plasmodium falciparum and β-haematin inhibition studies. All the compounds exhibited in vivo antimalarial activity better than that shown by the standard drug, chloroquine. Twelve out of fifteen compounds showed better inhibition than that of chloroquine against chloroquine-resistant W2 strain of Plasmodium falciparum. Ten compounds showed β-haematin inhibition, better than that of chloroquine, with IC 50 values in the range of 18-25µM. One compound, 3k, was found to be better than artemisinin against W2 strain of Plasmodium falciparum and also displayed the best β-haematin inhibitory activity, thereby becoming eligible to be explored as a potential lead for antimalarial chemotherapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

"Plasmo2D": an ancillary proteomic tool to aid identification of proteins from Plasmodium falciparum.

PubMed

Khachane, Amit; Kumar, Ranjit; Jain, Sanyam; Jain, Samta; Banumathy, Gowrishankar; Singh, Varsha; Nagpal, Saurabh; Tatu, Utpal

2005-01-01

Bioinformatics tools to aid gene and protein sequence analysis have become an integral part of biology in the post-genomic era. Release of the Plasmodium falciparum genome sequence has allowed biologists to define the gene and the predicted protein content as well as their sequences in the parasite. Using pI and molecular weight as characteristics unique to each protein, we have developed a bioinformatics tool to aid identification of proteins from Plasmodium falciparum. The tool makes use of a Virtual 2-DE generated by plotting all of the proteins from the Plasmodium database on a pI versus molecular weight scale. Proteins are identified by comparing the position of migration of desired protein spots from an experimental 2-DE and that on a virtual 2-DE. The procedure has been automated in the form of user-friendly software called "Plasmo2D". The tool can be downloaded from http://144.16.89.25/Plasmo2D.zip.

Development of a Photo-Cross-Linkable Diaminoquinazoline Inhibitor for Target Identification in Plasmodium falciparum.

PubMed

Lubin, Alexandra S; Rueda-Zubiaurre, Ainoa; Matthews, Holly; Baumann, Hella; Fisher, Fabio R; Morales-Sanfrutos, Julia; Hadavizadeh, Kate S; Nardella, Flore; Tate, Edward W; Baum, Jake; Scherf, Artur; Fuchter, Matthew J

2018-04-13

Diaminoquinazolines represent a privileged scaffold for antimalarial discovery, including use as putative Plasmodium histone lysine methyltransferase inhibitors. Despite this, robust evidence for their molecular targets is lacking. Here we report the design and development of a small-molecule photo-cross-linkable probe to investigate the targets of our diaminoquinazoline series. We demonstrate the effectiveness of our designed probe for photoaffinity labeling of Plasmodium lysates and identify similarities between the target profiles of the probe and the representative diaminoquinazoline BIX-01294. Initial pull-down proteomics experiments identified 104 proteins from different classes, many of which are essential, highlighting the suitability of the developed probe as a valuable tool for target identification in Plasmodium falciparum.

Effectiveness of artemether-lumefantrine provided by community health workers in under-five children with uncomplicated malaria in rural Tanzania: an open label prospective study.

PubMed

Ngasala, Billy E; Malmberg, Maja; Carlsson, Anja M; Ferreira, Pedro E; Petzold, Max G; Blessborn, Daniel; Bergqvist, Yngve; Gil, José P; Premji, Zul; Mårtensson, Andreas

2011-03-16

Home-management of malaria (HMM) strategy improves early access of anti-malarial medicines to high-risk groups in remote areas of sub-Saharan Africa. However, limited data are available on the effectiveness of using artemisinin-based combination therapy (ACT) within the HMM strategy. The aim of this study was to assess the effectiveness of artemether-lumefantrine (AL), presently the most favoured ACT in Africa, in under-five children with uncomplicated Plasmodium falciparum malaria in Tanzania, when provided by community health workers (CHWs) and administered unsupervised by parents or guardians at home. An open label, single arm prospective study was conducted in two rural villages with high malaria transmission in Kibaha District, Tanzania. Children presenting to CHWs with uncomplicated fever and a positive rapid malaria diagnostic test (RDT) were provisionally enrolled and provided AL for unsupervised treatment at home. Patients with microscopy confirmed P. falciparum parasitaemia were definitely enrolled and reviewed weekly by the CHWs during 42 days. Primary outcome measure was PCR corrected parasitological cure rate by day 42, as estimated by Kaplan-Meier survival analysis. This trial is registered with ClinicalTrials.gov, number NCT00454961. A total of 244 febrile children were enrolled between March-August 2007. Two patients were lost to follow up on day 14, and one patient withdrew consent on day 21. Some 141/241 (58.5%) patients had recurrent infection during follow-up, of whom 14 had recrudescence. The PCR corrected cure rate by day 42 was 93.0% (95% CI 88.3%-95.9%). The median lumefantrine concentration was statistically significantly lower in patients with recrudescence (97 ng/mL [IQR 0-234]; n = 10) compared with reinfections (205 ng/mL [114-390]; n = 92), or no parasite reappearance (217 [121-374] ng/mL; n = 70; p ≤ 0.046). Provision of AL by CHWs for unsupervised malaria treatment at home was highly effective, which provides evidence base for scaling-up implementation of HMM with AL in Tanzania.

Plasmodium falciparum ookinete expression of plasmepsin VII and plasmepsin X.

PubMed

Li, Fengwu; Bounkeua, Viengngeun; Pettersen, Kenneth; Vinetz, Joseph M

2016-02-24

Plasmodium invasion of the mosquito midgut is a population bottleneck in the parasite lifecycle. Interference with molecular mechanisms by which the ookinete invades the mosquito midgut is one potential approach to developing malaria transmission-blocking strategies. Plasmodium aspartic proteases are one such class of potential targets: plasmepsin IV (known to be present in the asexual stage food vacuole) was previously shown to be involved in Plasmodium gallinaceum infection of the mosquito midgut, and plasmepsins VII and plasmepsin X (not known to be present in the asexual stage food vacuole) are upregulated in Plasmodium falciparum mosquito stages. These (and other) parasite-derived enzymes that play essential roles during ookinete midgut invasion are prime candidates for transmission-blocking vaccines. Reverse transcriptase PCR (RT-PCR) was used to determine timing of P. falciparum plasmepsin VII (PfPM VII) and plasmepsin X (PfPM X) mRNA transcripts in parasite mosquito midgut stages. Protein expression was confirmed by western immunoblot and immunofluorescence assays (IFA) using anti-peptide monoclonal antibodies (mAbs) against immunogenic regions of PfPM VII and PfPM X. These antibodies were also used in standard membrane feeding assays (SMFA) to determine whether inhibition of these proteases would affect parasite transmission to mosquitoes. The Mann-Whitney U test was used to analyse mosquito transmission assay results. RT-PCR, western immunoblot and immunofluorescence assay confirmed expression of PfPM VII and PfPM X in mosquito stages. Whereas PfPM VII was expressed in zygotes and ookinetes, PfPM X was expressed in gametes, zygotes, and ookinetes. Antibodies against PfPM VII and PfPM X decreased P. falciparum invasion of the mosquito midgut when used at high concentrations, indicating that these proteases play a role in Plasmodium mosquito midgut invasion. Failure to generate genetic knockouts of these genes limited determination of the precise role of these proteases in parasite transmission but suggests that they are essential during the intraerythrocytic life cycle. PfPM VII and PfPM X are present in the mosquito-infective stages of P. falciparum. Standard membrane feeding assays demonstrate that antibodies against these proteins reduce the infectivity of P. falciparum for mosquitoes, suggesting their viability as transmission-blocking vaccine candidates. Further study of the role of these plasmepsins in P. falciparum biology is warranted.

Prevalence of molecular markers of anti-malarial drug resistance in Plasmodium vivax and Plasmodium falciparum in two districts of Nepal

PubMed Central

2011-01-01

Background Sulphadoxine-pyrimethamine (SP) and chloroquine (CQ) have been used in treatment of falciparum and vivax malaria in Nepal. Recently, resistance to both drugs have necessitated a change towards artemisinin combination therapy (ACT) against Plasmodium falciparum in highly endemic areas. However, SP is still used against P. falciparum infections in low endemic areas while CQ is used in suspected cases in areas with lack of diagnostic facilities. This study examines the prevalence of molecular markers of CQ and SP resistance in P. falciparum and Plasmodium vivax to determine if high levels of in vivo resistance are reflected at molecular level as well. Methods Finger prick blood samples (n = 189) were collected from malaria positive patients from two high endemic districts and analysed for single nucleotide polymorphisms (SNPs) in the resistance related genes of P. falciparum and P. vivax for CQ (Pfcrt, Pfmdr1, Pvmdr1) and SP (Pfdhfr, Pfdhps, Pvdhfr), using various PCR-based methods. Results and discussion Positive P. vivax and P. falciparum infections were identified by PCR in 92 and 41 samples respectively. However, some of these were negative in subsequent PCRs. Based on a few P. falciparum samples, the molecular level of CQ resistance in P. falciparum was high since nearly all parasites had the Pfcrt mutant haplotypes CVIET (55%) or SVMNT (42%), though frequency of the Pfmdr1 wild type haplotype was relatively low (35%). Molecular level of SP resistance in P. falciparum was found to be high. The most prevalent Pfdhfr haplotype was double mutant CNRNI (91%), while frequency of Pfdhps double mutant SGEAA and AGEAA were 38% and 33% respectively. Combined, the frequency of quadruple mutations (CNRNI-SGEAA/AGEAA) was 63%. Based on P. vivax samples, low CQ and SP resistance were most likely due to low prevalence of Pvmdr1 Y976F mutation (5%) and absence of triple/quadruple mutations in Pvdhfr. Conclusions Based on the limited number of samples, prevalence of CQ and SP resistance at molecular levels in the population in the study area were determined as high in P. falciparum and low in P. vivax. Therefore, CQ could still be used in the treatment of P. vivax infections, but this remains to be tested in vivo while the change to ACT for P. falciparum seems justified. PMID:21457533

Structure of Plasmodium falciparum ADP-ribosylation factor 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, William J.; Smith, Craig D.; Senkovich, Olga

Vesicular trafficking may play a crucial role in the pathogenesis and survival of the malaria parasite. ADP-ribosylation factors (ARFs) are among the major components of vesicular trafficking pathways in eukaryotes. The crystal structure of ARF1 GTPase from Plasmodium falciparum has been determined in the GDP-bound conformation at 2.5 {angstrom} resolution and is compared with the structures of mammalian ARF1s.

Patterns of mixed Plasmodium species infections among children six years and under in selected malaria hyper-endemic communities of Zambia: population-based survey observations.

PubMed

Sitali, Lungowe; Chipeta, James; Miller, John M; Moonga, Hawela B; Kumar, Nirbhay; Moss, William J; Michelo, Charles

2015-05-02

Although malaria is preventable and treatable, it still claims 660,000 lives every year globally with children under five years of age having the highest burden. In Zambia, malaria rapid diagnostic tests (RDTs) that only detect Plasmodium falciparum are the main confirmatory means for malaria diagnosis in most health facilities without microscopy services. As a consequence of this P. falciparum species diagnostic approach, non-falciparum malaria is not only under-diagnosed but entirely missed, thereby making the exact disease burden unknown. We thus investigated the prevalence of various Plasmodium spp. and associated burden of infection in selected communities in Zambia. Data from two malaria hyper-endemic provinces (Eastern and Luapula) of the 2012 National Malaria Indicator Survey (MIS), conducted between April and May 2012, were used. The MIS is a nationally representative, two-stage cluster survey conducted to coincide with the end of the malaria transmission season. Social, behavioural and background information were collected from households as part of the survey. Thick blood smears, RDTs and dried blood spots (DBS) were collected from children below six years of age. Slides were stained using Giemsa and examined by microscopy while polymerase chain reaction (PCR) was used to analyse the DBS for malaria Plasmodium spp. Multivariate logistic regression was employed to examine the association between background factors and malaria. Overall, 873 children younger than six years of age were surveyed. The overall prevalence of Plasmodium spp. by PCR was 54.3% (95% CI 51-57.6%). Of the total Plasmodium isolates, 88% were P. falciparum, 10.6% were mixed infections and 1.4% were non-falciparum mono infections. Among the mixed infections, the majority were a combination of P. falciparum and P. malariae (6.5% of all mixed infections). Children two years and older (2-5 years) had three-fold higher risk of mixed malaria infections (aOR 2.8 CI 1.31-5.69) than children younger than two years of age. The high prevalence of mixed Plasmodium spp. infections in this population stresses review of the current malaria RDT diagnostic approaches. The observed less incidence of mixed infections in children under two years of age compared to their older two-to-five-year-old counterparts is probably due to the protective maternal passive immunity, among other factors, in that age group.

High prevalence of very-low Plasmodium falciparum and Plasmodium vivax parasitaemia carriers in the Peruvian Amazon: insights into local and occupational mobility-related transmission.

PubMed

Carrasco-Escobar, Gabriel; Miranda-Alban, Julio; Fernandez-Miñope, Carlos; Brouwer, Kimberly C; Torres, Katherine; Calderon, Maritza; Gamboa, Dionicia; Llanos-Cuentas, Alejandro; Vinetz, Joseph M

2017-10-16

The incidence of malaria due both to Plasmodium falciparum and Plasmodium vivax in the Peruvian Amazon has risen in the past 5 years. This study tested the hypothesis that the maintenance and emergence of malaria in hypoendemic regions such as Amazonia is determined by submicroscopic and asymptomatic Plasmodium parasitaemia carriers. The present study aimed to precisely quantify the rate of very-low parasitaemia carriers in two sites of the Peruvian Amazon in relation to transmission patterns of P. vivax and P. falciparum in this area. This study was carried out within the Amazonian-ICEMR longitudinal cohort. Blood samples were collected for light microscopy diagnosis and packed red blood cell (PRBC) samples were analysed by qPCR. Plasma samples were tested for total IgG reactivity against recombinant PvMSP-10 and PfMSP-10 antigens by ELISA. Occupation and age 10 years and greater were considered surrogates of occupation-related mobility. Risk factors for P. falciparum and P. vivax infections detected by PRBC-qPCR were assessed by multilevel logistic regression models. Among 450 subjects, the prevalence of P. vivax by PRBC-PCR (25.1%) was sixfold higher than that determined by microscopy (3.6%). The prevalence of P. falciparum infection was 4.9% by PRBC-PCR and 0.2% by microscopy. More than 40% of infections had parasitaemia under 5 parasites/μL. Multivariate analysis for infections detected by PRBC-PCR showed that participants with recent settlement in the study area (AOR 2.1; 95% CI 1.03:4.2), age ≥ 30 years (AOR 3.3; 95% CI 1.6:6.9) and seropositivity to P. vivax (AOR 1.8; 95% CI 1.0:3.2) had significantly higher likelihood of P. vivax infection, while the odds of P. falciparum infection was higher for participants between 10 and 29 years (AOR 10.7; 95% CI 1.3:91.1) and with a previous P. falciparum infection (AOR 10.4; 95% CI 1.5:71.1). This study confirms the contrasting transmission patterns of P. vivax and P. falciparum in the Peruvian Amazon, with stable local transmission for P. vivax and the source of P. falciparum to the study villages dominated by very low parasitaemia carriers, age 10 years and older, who had travelled away from home for work and brought P. falciparum infection with them.

The detection of cryptic Plasmodium infection among villagers in Attapeu province, Lao PDR.

PubMed

Iwagami, Moritoshi; Keomalaphet, Sengdeuane; Khattignavong, Phonepadith; Soundala, Pheovaly; Lorphachan, Lavy; Matsumoto-Takahashi, Emilie; Strobel, Michel; Reinharz, Daniel; Phommasansack, Manisack; Hongvanthong, Bouasy; Brey, Paul T; Kano, Shigeyuki

2017-12-01

Although the malaria burden in the Lao PDR has gradually decreased, the elimination of malaria by 2030 presents many challenges. Microscopy and malaria rapid diagnostic tests (RDTs) are used to diagnose malaria in the Lao PDR; however, some studies have reported the prevalence of sub-microscopic Plasmodium infections or asymptomatic Plasmodium carriers in endemic areas. Thus, highly sensitive detection methods are needed to understand the precise malaria situation in these areas. A cross-sectional malaria field survey was conducted in 3 highly endemic malaria districts (Xaysetha, Sanamxay, Phouvong) in Attapeu province, Lao PDR in 2015, to investigate the precise malaria endemicity in the area; 719 volunteers from these villages participated in the survey. Microscopy, RDTs and a real-time nested PCR were used to detect Plasmodium infections and their results were compared. A questionnaire survey of all participants was also conducted to estimate risk factors of Plasmodium infection. Numbers of infections detected by the three methods were microscopy: P. falciparum (n = 1), P. vivax (n = 2); RDTs: P. falciparum (n = 2), P. vivax (n = 3); PCR: Plasmodium (n = 47; P. falciparum [n = 4], P. vivax [n = 41], mixed infection [n = 2]; 6.5%, 47/719). Using PCR as a reference, the sensitivity and specificity of microscopy were 33.3% and 100.0%, respectively, for detecting P. falciparum infection, and 7.0% and 100.0%, for detecting P. vivax infection. Among the 47 participants with parasitemia, only one had a fever (≥37.5°C) and 31 (66.0%) were adult males. Risk factors of Plasmodium infection were males and soldiers, whereas a risk factor of asymptomatic Plasmodium infection was a history of ≥3 malaria episodes. There were many asymptomatic Plasmodium carriers in the study areas of Attapeu province in 2015. Adult males, probably soldiers, were at high risk for malaria infection. P. vivax, the dominant species, accounted for 87.2% of the Plasmodium infections among the participants. To achieve malaria elimination in the Lao PDR, highly sensitive diagnostic tests, including PCR-based diagnostic methods should be used, and plans targeting high-risk populations and elimination of P. vivax should be designed and implemented.

Deciphering the key residues in Plasmodium falciparum beta-ketoacyl acyl carrier protein reductase responsible for interactions with Plasmodium falciparum acyl carrier protein.

PubMed

Karmodiya, Krishanpal; Modak, Rahul; Sahoo, Nirakar; Sajad, Syed; Surolia, Namita

2008-10-01

The type II fatty acid synthase (FAS) pathway of Plasmodium falciparum is a validated unique target for developing novel antimalarials, due to its intrinsic differences from the typeI pathway operating in humans. beta-Ketoacyl acyl carrier protein (ACP) reductase (FabG) performs the NADPH-dependent reduction of beta-ketoacyl-ACP to beta-hydroxyacyl-ACP, the first reductive step in the elongation cycle of fatty acid biosynthesis. In this article, we report intensive studies on the direct interactions of Plasmodium FabG and Plasmodium ACP in solution, in the presence and absence of its cofactor, NADPH, by monitoring the change in intrinsic fluorescence of P.falciparum FabG (PfFabG) and by surface plasmon resonance. To address the issue of the importance of the residues involved in strong, specific and stoichiometric binding of PfFabG to P.falciparum ACP (PfACP), we mutated Arg187, Arg190 and Arg230 of PfFabG. The activities of the mutants were assessed using both an ACP-dependent and an ACP-independent assay. The affinities of all the PfFabG mutants for acetoacetyl-ACP (the physiological substrate) were reduced to different extents as compared to wild-type PfFabG, but were equally active in biochemical assays with the substrate analog acetoacetyl-CoA. Kinetic analysis and studies of direct binding between PfFabG and PfACP confirmed the identification of Arg187 and Arg230 as critical residues for the PfFabG-PfACP interactions. Our studies thus reveal the significance of the positively charged/hydrophobic patch located adjacent to the active site cavities of PfFabG for interactions with PfACP.

The Relative Contribution of Symptomatic and Asymptomatic Plasmodium vivax and Plasmodium falciparum Infections to the Infectious Reservoir in a Low-Endemic Setting in Ethiopia.

PubMed

Tadesse, Fitsum G; Slater, Hannah C; Chali, Wakweya; Teelen, Karina; Lanke, Kjerstin; Belachew, Mulualem; Menberu, Temesgen; Shumie, Girma; Shitaye, Getasew; Okell, Lucy C; Graumans, Wouter; van Gemert, Geert-Jan; Kedir, Soriya; Tesfaye, Addisu; Belachew, Feleke; Abebe, Wake; Mamo, Hassen; Sauerwein, Robert; Balcha, Taye; Aseffa, Abraham; Yewhalaw, Delenasaw; Gadisa, Endalamaw; Drakeley, Chris; Bousema, Teun

2018-06-01

The majority of Plasmodium vivax and Plasmodium falciparum infections in low-endemic settings are asymptomatic. The relative contribution to the infectious reservoir of these infections compared to clinical malaria cases is currently unknown. We assessed infectivity of passively recruited symptomatic malaria patients (n = 41) and community-recruited asymptomatic individuals with microscopy-detected (n = 41) and polymerase chain reaction (PCR)-detected infections (n = 82) using membrane feeding assays with Anopheles arabiensis mosquitoes in Adama, Ethiopia. Malaria incidence and prevalence data were used to estimate the contributions of these populations to the infectious reservoir. Overall, 34.9% (29/83) of P. vivax- and 15.1% (8/53) P. falciparum-infected individuals infected ≥1 mosquitoes. Mosquito infection rates were strongly correlated with asexual parasite density for P. vivax (ρ = 0.63; P < .001) but not for P. falciparum (ρ = 0.06; P = .770). Plasmodium vivax symptomatic infections were more infectious to mosquitoes (infecting 46.5% of mosquitoes, 307/660) compared to asymptomatic microscopy-detected (infecting 12.0% of mosquitoes, 80/667; P = .005) and PCR-detected infections (infecting 0.8% of mosquitoes, 6/744; P < .001). Adjusting for population prevalence, symptomatic, asymptomatic microscopy-detected, and PCR-detected infections were responsible for 8.0%, 76.2%, and 15.8% of the infectious reservoir for P. vivax, respectively. For P. falciparum, mosquito infections were sparser and also predominantly from asymptomatic infections. In this low-endemic setting aiming for malaria elimination, asymptomatic infections were highly prevalent and responsible for the majority of onward mosquito infections. The early identification and treatment of asymptomatic infections might accelerate elimination efforts.

Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras

PubMed Central

2012-01-01

Background Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite’s circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Methods Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. Results and conclusion A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77) for pvama-1; 23 (n = 84) for pvcsp; and 23 (n = 35) for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2) was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30) block 2 (K1, MAD20, and RO33), and both allelic families described for the central domain of pfmsp-2 (n = 11) (3D7 and FC27) were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission. PMID:23181845

Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras.

PubMed

Lopez, Ana Cecilia; Ortiz, Andres; Coello, Jorge; Sosa-Ochoa, Wilfredo; Torres, Rosa E Mejia; Banegas, Engels I; Jovel, Irina; Fontecha, Gustavo A

2012-11-26

Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite's circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77) for pvama-1; 23 (n = 84) for pvcsp; and 23 (n = 35) for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2) was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30) block 2 (K1, MAD20, and RO33), and both allelic families described for the central domain of pfmsp-2 (n = 11) (3D7 and FC27) were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission.

Prevalence of K13-propeller gene polymorphisms among Plasmodium falciparum parasites isolated from adult symptomatic patients in northern Uganda.

PubMed

Ocan, Moses; Bwanga, Freddie; Okeng, Alfred; Katabazi, Fred; Kigozi, Edgar; Kyobe, Samuel; Ogwal-Okeng, Jasper; Obua, Celestino

2016-08-19

In the absence of an effective vaccine, malaria treatment and eradication is still a challenge in most endemic areas globally. This is especially the case with the current reported emergence of resistance to artemisinin agents in Southeast Asia. This study therefore explored the prevalence of K13-propeller gene polymorphisms among Plasmodium falciparum parasites in northern Uganda. Adult patients (≥18 years) presenting to out-patients department of Lira and Gulu regional referral hospitals in northern Uganda were randomly recruited. Laboratory investigation for presence of plasmodium infection among patients was done using Plasmodium falciparum exclusive rapid diagnostic test, histidine rich protein-2 (HRP2) (Pf). Finger prick capillary blood from patients with a positive malaria test was spotted on a filter paper Whatman no. 903. The parasite DNA was extracted using chelex resin method and sequenced for mutations in K13-propeller gene using Sanger sequencing. PCR DNA sequence products were analyzed using in DNAsp 5.10.01software, data was further processed in Excel spreadsheet 2007. A total of 60 parasite DNA samples were sequenced. Polymorphisms in the K13-propeller gene were detected in four (4) of the 60 parasite DNA samples sequenced. A non-synonymous polymorphism at codon 533 previously detected in Cambodia was found in the parasite DNA samples analyzed. Polymorphisms at codon 522 (non-synonymous) and codon 509 (synonymous) were also found in the samples analyzed. The study found evidence of positive selection in the Plasmodium falciparum population in northern Uganda (Tajima's D = -1.83205; Fu and Li's D = -1.82458). Polymorphism in the K13-propeller gene previously reported in Cambodia has been found in the Ugandan Plasmodium falciparum parasites. There is need for continuous surveillance for artemisinin resistance gene markers in the country.

Evaluation of Ebola virus inactivation procedures for Plasmodium falciparum malaria diagnostics.

PubMed

Lau, Rachel; Wang, Amanda; Chong-Kit, Ann; Ralevski, Filip; Boggild, Andrea K

2015-04-01

Plasmodium falciparum malaria is highly endemic in the three most affected countries in the current epidemic of Ebola virus disease (EVD) in West Africa. As EVD and malaria are clinically indistinguishable, both remain part of the differential diagnosis of ill travelers from returning from areas of EVD transmission. We compared the performances of a rapid diagnostic test (BinaxNOW) and real-time PCR with P. falciparum-positive specimens before and after heat and Triton X-100 inactivation, and we documented no loss of sensitivity. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Novel short chain chloroquine analogues retain activity against chloroquine resistant K1 Plasmodium falciparum.

PubMed

Stocks, Paul A; Raynes, Kaylene J; Bray, Patrick G; Park, B Kevin; O'Neill, Paul M; Ward, Stephen A

2002-11-07

A series of short chain chloroquine (CQ) derivatives have been synthesized in one step from readily available starting materials. The diethylamine function of CQ is replaced by shorter alkylamine groups (4-9) containing secondary or tertiary terminal nitrogens. Some of these derivatives are significantly more potent than CQ against a CQ resistant strain of Plasmodium falciparum in vitro. We conclude that the ability to accumulate at higher concentrations within the food vacuole of the parasite is an important parameter that dictates their potency against CQ sensitive and the chloroquine resistant K1 P. falciparum.

Genetic deletion of HRP2 and HRP3 in Indian Plasmodium falciparum population and false negative malaria rapid diagnostic test.

PubMed

Kumar, Navin; Pande, Veena; Bhatt, R M; Shah, Naman K; Mishra, Neelima; Srivastava, Bina; Valecha, Neena; Anvikar, Anupkumar R

2013-01-01

Genetic polymorphisms in diagnostic antigens are important factors responsible for variable performance of rapid diagnostic tests. Additionally, the failure of antigen expression due to gene deletion may also contribute to variable performance. We report Indian Plasmodium falciparum field isolates lacking both Pfhrp2 and Pfhrp3 genes leading to false negative results of rapid diagnostic tests. The study highlights need to determine the prevalence of P. falciparum isolates lacking these genes in larger field populations in India. Copyright © 2012 Elsevier B.V. All rights reserved.

Ape parasite origins of human malaria virulence genes

PubMed Central

Larremore, Daniel B.; Sundararaman, Sesh A.; Liu, Weimin; Proto, William R.; Clauset, Aaron; Loy, Dorothy E.; Speede, Sheri; Plenderleith, Lindsey J.; Sharp, Paul M.; Hahn, Beatrice H.; Rayner, Julian C.; Buckee, Caroline O.

2015-01-01

Antigens encoded by the var gene family are major virulence factors of the human malaria parasite Plasmodium falciparum, exhibiting enormous intra- and interstrain diversity. Here we use network analysis to show that var architecture and mosaicism are conserved at multiple levels across the Laverania subgenus, based on var-like sequences from eight single-species and three multi-species Plasmodium infections of wild-living or sanctuary African apes. Using select whole-genome amplification, we also find evidence of multi-domain var structure and synteny in Plasmodium gaboni, one of the ape Laverania species most distantly related to P. falciparum, as well as a new class of Duffy-binding-like domains. These findings indicate that the modular genetic architecture and sequence diversity underlying var-mediated host-parasite interactions evolved before the radiation of the Laverania subgenus, long before the emergence of P. falciparum. PMID:26456841

Density-dependent blood stage Plasmodium falciparum suppresses malaria super-infection in a malaria holoendemic population.

PubMed

Pinkevych, Mykola; Petravic, Janka; Chelimo, Kiprotich; Vulule, John; Kazura, James W; Moormann, Ann M; Davenport, Miles P

2013-11-01

Recent studies of Plasmodium berghei malaria in mice show that high blood-stage parasitemia levels inhibit the development of subsequent liver-stage infections. Whether a similar inhibitory effect on liver-stage Plasmodium falciparum by blood-stage infection occurs in humans is unknown. We have analyzed data from a treatment-time-to-infection cohort of children < 10 years of age residing in a malaria holoendemic area of Kenya where people experience a new blood-stage infection approximately every 2 weeks. We hypothesized that if high parasitemia blocked the liver stage, then high levels of parasitemia should be followed by a "skipped" peak of parasitemia. Statistical analysis of "natural infection" field data and stochastic simulation of infection dynamics show that the data are consistent with high P. falciparum parasitemia inhibiting liver-stage parasite development in humans.

Plasmodium vivax Malaria in Cambodia

PubMed Central

Siv, Sovannaroth; Roca-Feltrer, Arantxa; Vinjamuri, Seshu Babu; Bouth, Denis Mey; Lek, Dysoley; Rashid, Mohammad Abdur; By, Ngau Peng; Popovici, Jean; Huy, Rekol; Menard, Didier

2016-01-01

The Cambodian National Strategic Plan for Elimination of Malaria aims to move step by step toward elimination of malaria across Cambodia with an initial focus on Plasmodium falciparum malaria before achieving elimination of all forms of malaria, including Plasmodium vivax in 2025. The emergence of artemisinin-resistant P. falciparum in western Cambodia over the last decade has drawn global attention to support the ultimate goal of P. falciparum elimination, whereas the control of P. vivax lags much behind, making the 2025 target gradually less achievable unless greater attention is given to P. vivax elimination in the country. The following review presents in detail the past and current situation regarding P. vivax malaria, activities of the National Malaria Control Program, and interventional measures applied. Constraints and obstacles that can jeopardize our efforts to eliminate this parasite species are discussed. PMID:27708187

Genetic characterization of an epidemic of Plasmodium falciparum malaria among Yanomami Amerindians.

PubMed

Laserson, K F; Petralanda, I; Almera, R; Barker, R H; Spielman, A; Maguire, J H; Wirth, D F

1999-12-01

Malaria parasites are genetically diverse at all levels of endemicity. In contrast, the merozoite surface protein (MSP) alleles in samples from 2 isolated populations of Yanomami Amerindians during an epidemic of Plasmodium falciparum were identical. The nonvariable restriction fragment length polymorphism patterns further suggested that the sequential outbreak comprised only a single P. falciparum genotype. By examination of serial samples from single human infections, the MSP characteristics were found to remain constant throughout the course of infection. An apparent clonal population structure of parasites seemed to cause outbreaks in small isolated villages. The use of standard molecular epidemiologic methods to measure genetic diversity in malaria revealed the occurrence of a genetically monomorphic population of P. falciparum within a human community.

A semi-automated luminescence based standard membrane feeding assay identifies novel small molecules that inhibit transmission of malaria parasites by mosquitoes

PubMed Central

Vos, Martijn W.; Stone, Will J. R.; Koolen, Karin M.; van Gemert, Geert-Jan; van Schaijk, Ben; Leroy, Didier; Sauerwein, Robert W.; Bousema, Teun; Dechering, Koen J.

2015-01-01

Current first-line treatments for uncomplicated falciparum malaria rapidly clear the asexual stages of the parasite, but do not fully prevent parasite transmission by mosquitoes. The standard membrane feeding assay (SMFA) is the biological gold standard assessment of transmission reducing activity (TRA), but its throughput is limited by the need to determine mosquito infection status by dissection and microscopy. Here we present a novel dissection-free luminescence based SMFA format using a transgenic Plasmodium falciparum reporter parasite without resistance to known antimalarials and therefore unrestricted in its utility in compound screening. Analyses of sixty-five compounds from the Medicines for Malaria Venture validation and malaria boxes identified 37 compounds with high levels of TRA (>80%); different assay modes allowed discrimination between gametocytocidal and downstream modes of action. Comparison of SMFA data to published assay formats for predicting parasite infectivity indicated that individual in vitro screens show substantial numbers of false negatives. These results highlight the importance of the SMFA in the screening pipeline for transmission reducing compounds and present a rapid and objective method. In addition we present sixteen diverse chemical scaffolds from the malaria box that may serve as a starting point for further discovery and development of malaria transmission blocking drugs. PMID:26687564

The spectrum of retinopathy in adults with Plasmodium falciparum malaria.

PubMed

Maude, Richard J; Beare, Nicholas A V; Abu Sayeed, Abdullah; Chang, Christina C; Charunwatthana, Prakaykaew; Faiz, M Abul; Hossain, Amir; Yunus, Emran Bin; Hoque, M Gofranul; Hasan, Mahtab Uddin; White, Nicholas J; Day, Nicholas P J; Dondorp, Arjen M

2009-07-01

A specific retinopathy has been described in African children with cerebral malaria, but in adults this has not been extensively studied. Since the structure and function of the retinal vasculature greatly resembles the cerebral vasculature, study of retinal changes can reveal insights into the pathophysiology of cerebral malaria. A detailed observational study of malarial retinopathy in Bangladeshi adults was performed using high-definition portable retinal photography. Retinopathy was present in 17/27 adults (63%) with severe malaria and 14/20 adults (70%) with cerebral malaria. Moderate or severe retinopathy was more frequent in cerebral malaria (11/20, 55%) than in uncomplicated malaria (3/15, 20%; P=0.039), bacterial sepsis (0/5, 0%; P=0.038) or healthy controls (0/18, 0%; P<0.001). The spectrum of malarial retinopathy was similar to that previously described in African children, but no vessel discolouration was observed. The severity of retinal whitening correlated with admission venous plasma lactate (P=0.046), suggesting that retinal ischaemia represents systemic ischaemia. In conclusion, retinal changes related to microvascular obstruction were common in adults with severe falciparum malaria and correlated with disease severity and coma, suggesting that a compromised microcirculation has important pathophysiological significance in severe and cerebral malaria. Portable retinal photography has potential as a valuable tool to study malarial retinopathy.

Detection of anti-neutrophil cytoplasmic antibodies after acute Plasmodium falciparum malaria.

PubMed Central

Wenisch, C; Wenisch, H; Bankl, H C; Exner, M; Graninger, W; Looareesuwan, S; Rumpold, H

1996-01-01

Four of 30 patients with Plasmodium falciparum infection in Bangkok, Thailand, were positive for anti-neutrophil cytoplasmic antibodies by indirect immunofluorescence 1 month after antimalarial therapy. No myeloperoxidase, proteinase 3, lactoferrin, or elastase reactivity was found. Since no evidence of vasculitis was seen in these patients, anti-neutrophil cytoplasmic antibody production in malaria-infected susceptible patients probably represents a secondary response, indicating neutrophil activation. PMID:8770517

Multidrug ATP-binding cassette transporters are essential for hepatic development of Plasmodium sporozoites.

PubMed

Rijpma, Sanna R; van der Velden, Maarten; González-Pons, Maria; Annoura, Takeshi; van Schaijk, Ben C L; van Gemert, Geert-Jan; van den Heuvel, Jeroen J M W; Ramesar, Jai; Chevalley-Maurel, Severine; Ploemen, Ivo H; Khan, Shahid M; Franetich, Jean-Francois; Mazier, Dominique; de Wilt, Johannes H W; Serrano, Adelfa E; Russel, Frans G M; Janse, Chris J; Sauerwein, Robert W; Koenderink, Jan B; Franke-Fayard, Blandine M

2016-03-01

Multidrug resistance-associated proteins (MRPs) belong to the C-family of ATP-binding cassette (ABC) transport proteins and are known to transport a variety of physiologically important compounds and to be involved in the extrusion of pharmaceuticals. Rodent malaria parasites encode a single ABC transporter subfamily C protein, whereas human parasites encode two: MRP1 and MRP2. Although associated with drug resistance, their biological function and substrates remain unknown. To elucidate the role of MRP throughout the parasite life cycle, Plasmodium berghei and Plasmodium falciparum mutants lacking MRP expression were generated. P. berghei mutants lacking expression of the single MRP as well as P. falciparum mutants lacking MRP1, MRP2 or both proteins have similar blood stage growth kinetics and drug-sensitivity profiles as wild type parasites. We show that MRP1-deficient parasites readily invade primary human hepatocytes and develop into mature liver stages. In contrast, both P. falciparum MRP2-deficient parasites and P. berghei mutants lacking MRP protein expression abort in mid to late liver stage development, failing to produce mature liver stages. The combined P. berghei and P. falciparum data are the first demonstration of a critical role of an ABC transporter during Plasmodium liver stage development. © 2015 John Wiley & Sons Ltd.

Colombian Anopheles triannulatus (Diptera: Culicidae) Naturally Infected with Plasmodium spp.

PubMed Central

Rosero, Doris A.; Naranjo-Diaz, Nelson; Alvarez, Natalí; Cienfuegos, Astrid V.; Luckhart, Shirley

2013-01-01

The role of Anopheles triannulatus as a local vector has not yet been defined for malaria-endemic regions of Colombia. Therefore, the aim of this work was to detect An. triannulatus naturally infected with Plasmodium spp., as an approximation to determining its importance as malaria vector in the country. A total of 510 An. triannulatus were collected in six malaria-endemic localities of NW and SE Colombia from January 2009 to March 2011. In the NW, two specimens were naturally infected; one with Plasmodium vivax VK247, collected biting on humans and the other with Plasmodium falciparum, collected resting on cattle. In the SE, two specimens were positive for P. falciparum. Although these results show An. triannulatus naturally infected with Plasmodium, further studies are recommended to demonstrate the epidemiological importance of this species in malaria-endemic regions of Colombia. PMID:27335865

Colombian Anopheles triannulatus (Diptera: Culicidae) Naturally Infected with Plasmodium spp.

PubMed

Rosero, Doris A; Naranjo-Diaz, Nelson; Alvarez, Natalí; Cienfuegos, Astrid V; Torres, Carolina; Luckhart, Shirley; Correa, Margarita M

2013-01-01

The role of Anopheles triannulatus as a local vector has not yet been defined for malaria-endemic regions of Colombia. Therefore, the aim of this work was to detect An. triannulatus naturally infected with Plasmodium spp., as an approximation to determining its importance as malaria vector in the country. A total of 510 An. triannulatus were collected in six malaria-endemic localities of NW and SE Colombia from January 2009 to March 2011. In the NW, two specimens were naturally infected; one with Plasmodium vivax VK247, collected biting on humans and the other with Plasmodium falciparum, collected resting on cattle. In the SE, two specimens were positive for P. falciparum. Although these results show An. triannulatus naturally infected with Plasmodium, further studies are recommended to demonstrate the epidemiological importance of this species in malaria-endemic regions of Colombia.

Towards development of aptamers that specifically bind to lactate dehydrogenase of Plasmodium falciparum through epitopic targeting.

PubMed

Frith, Kelly-Anne; Fogel, Ronen; Goldring, J P Dean; Krause, Robert G E; Khati, Makobetsa; Hoppe, Heinrich; Cromhout, Mary E; Jiwaji, Meesbah; Limson, Janice L

2018-05-03

Early detection is crucial for the effective treatment of malaria, particularly in those cases infected with Plasmodium falciparum. There is a need for diagnostic devices with the capacity to distinguish P. falciparum from other strains of malaria. Here, aptamers generated against targeted species-specific epitopes of P. falciparum lactate dehydrogenase (rPfLDH) are described. Two classes of aptamers bearing high binding affinity and specificity for recombinant P. falciparum lactate dehydrogenase (rPfLDH) and P. falciparum-specific lactate dehydrogenase epitopic oligopeptide (LDHp) were separately generated. Structurally-relevant moieties with particular consensus sequences (GGTAG and GGCG) were found in aptamers reported here and previously published, confirming their importance in recognition of the target, while novel moieties particular to this work (ATTAT and poly-A stretches) were identified. Aptamers with diagnostically-supportive functions were synthesized, prime examples of which are the aptamers designated as LDHp 1, LDHp 11 and rLDH 4 and rLDH 15 in work presented herein. Of the sampled aptamers raised against the recombinant protein, rLDH 4 showed the highest binding to the target rPfLDH in the ELONA assay, with both rLDH 4 and rLDH 15 indicating an ability to discriminate between rPfLDH and rPvLDH. LDHp 11 was generated against a peptide selected as a unique P. falciparum LDH peptide. The aptamer, LDHp 11, like antibodies against the same peptide, only detected rPfLDH and discriminated between rPfLDH and rPvLDH. This was supported by affinity binding experiments where only aptamers generated against a unique species-specific epitope showed an ability to preferentially bind to rPfLDH relative to rPvLDH rather than those generated against the whole recombinant protein. In addition, rLDH 4 and LDHp 11 demonstrated in situ binding to P. falciparum cells during confocal microscopy. The utilization and application of LDHp 11, an aptamer generated against a unique species-specific epitope of P. falciparum LDH indicated the ability to discriminate between recombinant P. falciparum and Plasmodium vivax LDH. This aptamer holds promise as a biorecognition element in malaria diagnostic devices for the detection, and differentiation, of P. falciparum and P. vivax malaria infections. This study paves the way to explore aptamer generation against targeted species-specific epitopes of other Plasmodium species.

Species-specific escape of Plasmodium sporozoites from oocysts of avian, rodent, and human malarial parasites.

PubMed

Orfano, Alessandra S; Nacif-Pimenta, Rafael; Duarte, Ana P M; Villegas, Luis M; Rodrigues, Nilton B; Pinto, Luciana C; Campos, Keillen M M; Pinilla, Yudi T; Chaves, Bárbara; Barbosa Guerra, Maria G V; Monteiro, Wuelton M; Smith, Ryan C; Molina-Cruz, Alvaro; Lacerda, Marcus V G; Secundino, Nágila F C; Jacobs-Lorena, Marcelo; Barillas-Mury, Carolina; Pimenta, Paulo F P

2016-08-02

Malaria is transmitted when an infected mosquito delivers Plasmodium sporozoites into a vertebrate host. There are many species of Plasmodium and, in general, the infection is host-specific. For example, Plasmodium gallinaceum is an avian parasite, while Plasmodium berghei infects mice. These two parasites have been extensively used as experimental models of malaria transmission. Plasmodium falciparum and Plasmodium vivax are the most important agents of human malaria, a life-threatening disease of global importance. To complete their life cycle, Plasmodium parasites must traverse the mosquito midgut and form an oocyst that will divide continuously. Mature oocysts release thousands of sporozoites into the mosquito haemolymph that must reach the salivary gland to infect a new vertebrate host. The current understanding of the biology of oocyst formation and sporozoite release is mostly based on experimental infections with P. berghei, and the conclusions are generalized to other Plasmodium species that infect humans without further morphological analyses. Here, it is described the microanatomy of sporozoite escape from oocysts of four Plasmodium species: the two laboratory models, P. gallinaceum and P. berghei, and the two main species that cause malaria in humans, P. vivax and P. falciparum. It was found that sporozoites have species-specific mechanisms of escape from the oocyst. The two model species of Plasmodium had a common mechanism, in which the oocyst wall breaks down before sporozoites emerge. In contrast, P. vivax and P. falciparum sporozoites show a dynamic escape mechanism from the oocyst via polarized propulsion. This study demonstrated that Plasmodium species do not share a common mechanism of sporozoite escape, as previously thought, but show complex and species-specific mechanisms. In addition, the knowledge of this phenomenon in human Plasmodium can facilitate transmission-blocking studies and not those ones only based on the murine and avian models.

IgG antibodies to synthetic GPI are biomarkers of immune-status to both Plasmodium falciparum and Plasmodium vivax malaria in young children.

PubMed

França, Camila T; Li Wai Suen, Connie S N; Carmagnac, Amandine; Lin, Enmoore; Kiniboro, Benson; Siba, Peter; Schofield, Louis; Mueller, Ivo

2017-09-25

Further reduction in malaria prevalence and its eventual elimination would be greatly facilitated by the development of biomarkers of exposure and/or acquired immunity to malaria, as well as the deployment of effective vaccines against Plasmodium falciparum and Plasmodium vivax. A better understanding of the acquisition of immunity in naturally-exposed populations is essential for the identification of antigens useful as biomarkers, as well as to inform rational vaccine development. ELISA was used to measure total IgG to a synthetic form of glycosylphosphatidylinositol from P. falciparum (PfGPI) in a cohort of 1-3 years old Papua New Guinea children with well-characterized individual differences in exposure to P. falciparum and P. vivax blood-stage infections. The relationship between IgG levels to PfGPI and measures of recent and past exposure to P. falciparum and P. vivax infections was investigated, as well as the association between antibody levels and prospective risk of clinical malaria over 16 months of follow-up. Total IgG levels to PfGPI were low in the young children tested. Antibody levels were higher in the presence of P. falciparum or P. vivax infections, but short-lived. High IgG levels were associated with higher risk of P. falciparum malaria (IRR 1.33-1.66, P = 0.008-0.027), suggesting that they are biomarkers of increased exposure to P. falciparum infections. Given the cross-reactive nature of antibodies to PfGPI, high IgG levels were also associated with reduced risk of P. vivax malaria (IRR 0.65-0.67, P = 0.039-0.044), indicating that these antibodies are also markers of acquired immunity to P. vivax. This study highlights that in young children, IgG to PfGPI might be a useful marker of immune-status to both P. falciparum and P. vivax infections, and potentially useful to help malaria control programs to identify populations at-risk. Further functional studies are necessary to confirm the potential of PfGPI as a target for vaccine development.

Plasmodium vivax and Plasmodium falciparum infections in the Republic of Djibouti: evaluation of their prevalence and potential determinants

PubMed Central

2012-01-01

Background Formerly known as a hypoendemic malaria country, the Republic of Djibouti declared the goal of pre-eliminating malaria in 2006. The aim of the present study was to evaluate the prevalence of Plasmodium falciparum, Plasmodium vivax and mixed infections in the Djiboutian population by using serological tools and to identify potential determinants of the disease and hotspots of malaria transmission within the country. Methods The prevalence of P. falciparum and P. vivax within the districts of the capital city and the rest of the Republic of Djibouti were assessed using 13 and 2 serological markers, respectively. The relationship between the immune humeral response to P. falciparum and P. vivax and variables such as age, gender, wealth status, urbanism, educational level, distance to rivers/lakes, living area, having fever in the last month, and staying in a malaria-endemic country more than one year was estimated and analysed by questionnaires administered to 1910 Djiboutians. Multivariate ordinal logistic regression models of the immune humeral response were obtained for P. falciparum and P. vivax. Results The P. falciparum and P. vivax seroprevalence rates were 31.5%, CI95% [29.4-33.7] and 17.5%, CI95% [15.8-19.3], respectively. Protective effects against P. falciparum and P. vivax were female gender, educational level, and never having visited a malaria-endemic area for more than one year. For P. falciparum only, a protective effect was observed for not having a fever in the last month, living more than 1.5 km away from lakes and rivers, and younger ages. Conclusions This is the first study that assessed the seroprevalence of P. vivax in the Republic of Djibouti. It is necessary to improve knowledge of this pathogen in order to create an effective elimination programme. As supported by recent observations on the subject, the Republic of Djibouti has probably demonstrated a real decrease in the transmission of P. falciparum in the past seven years, which should encourage authorities to improve efforts toward elimination. PMID:23190709

Plasmodium vivax and Plasmodium falciparum infections in the Republic of Djibouti: evaluation of their prevalence and potential determinants.

PubMed

Khaireh, Bouh Abdi; Briolant, Sébastien; Pascual, Aurélie; Mokrane, Madjid; Machault, Vanessa; Travaillé, Christelle; Khaireh, Mohamed Abdi; Farah, Ismail Hassan; Ali, Habib Moussa; Abdi, Abdul-Ilah Ahmed; Ayeh, Souleiman Nour; Darar, Houssein Youssouf; Ollivier, Lénaïck; Waiss, Mohamed Killeh; Bogreau, Hervé; Rogier, Christophe; Pradines, Bruno

2012-11-28

Formerly known as a hypoendemic malaria country, the Republic of Djibouti declared the goal of pre-eliminating malaria in 2006. The aim of the present study was to evaluate the prevalence of Plasmodium falciparum, Plasmodium vivax and mixed infections in the Djiboutian population by using serological tools and to identify potential determinants of the disease and hotspots of malaria transmission within the country. The prevalence of P. falciparum and P. vivax within the districts of the capital city and the rest of the Republic of Djibouti were assessed using 13 and 2 serological markers, respectively. The relationship between the immune humeral response to P. falciparum and P. vivax and variables such as age, gender, wealth status, urbanism, educational level, distance to rivers/lakes, living area, having fever in the last month, and staying in a malaria-endemic country more than one year was estimated and analysed by questionnaires administered to 1910 Djiboutians. Multivariate ordinal logistic regression models of the immune humeral response were obtained for P. falciparum and P. vivax. The P. falciparum and P. vivax seroprevalence rates were 31.5%, CI95% [29.4-33.7] and 17.5%, CI95% [15.8-19.3], respectively. Protective effects against P. falciparum and P. vivax were female gender, educational level, and never having visited a malaria-endemic area for more than one year. For P. falciparum only, a protective effect was observed for not having a fever in the last month, living more than 1.5 km away from lakes and rivers, and younger ages. This is the first study that assessed the seroprevalence of P. vivax in the Republic of Djibouti. It is necessary to improve knowledge of this pathogen in order to create an effective elimination programme. As supported by recent observations on the subject, the Republic of Djibouti has probably demonstrated a real decrease in the transmission of P. falciparum in the past seven years, which should encourage authorities to improve efforts toward elimination.

Plasmodium falciparum and Plasmodium vivax Demonstrate Contrasting Chloroquine Resistance Reversal Phenotypes.

PubMed

Wirjanata, Grennady; Handayuni, Irene; Prayoga, Pak; Leonardo, Leo; Apriyanti, Dwi; Trianty, Leily; Wandosa, Ruland; Gobay, Basbak; Kenangalem, Enny; Poespoprodjo, Jeanne Rini; Noviyanti, Rintis; Kyle, Dennis E; Cheng, Qin; Price, Ric N; Marfurt, Jutta

2017-08-01

High-grade chloroquine (CQ) resistance has emerged in both Plasmodium falciparum and P. vivax The aim of the present study was to investigate the phenotypic differences of CQ resistance in both of these species and the ability of known CQ resistance reversal agents (CQRRAs) to alter CQ susceptibility. Between April 2015 and April 2016, the potential of verapamil (VP), mibefradil (MF), L703,606 (L7), and primaquine (PQ) to reverse CQ resistance was assessed in 46 P. falciparum and 34 P. vivax clinical isolates in Papua, Indonesia, where CQ resistance is present in both species, using a modified schizont maturation assay. In P. falciparum , CQ 50% inhibitory concentrations (IC 50 s) were reduced when CQ was combined with VP (1.4-fold), MF (1.2-fold), L7 (4.2-fold), or PQ (1.8-fold). The degree of CQ resistance reversal in P. falciparum was highly correlated with CQ susceptibility for all CQRRAs ( R 2 = 0.951, 0.852, 0.962, and 0.901 for VP, MF, L7, and PQ, respectively), in line with observations in P. falciparum laboratory strains. In contrast, no reduction in the CQ IC 50 s was observed with any of the CQRRAs in P. vivax , even in those isolates with high chloroquine IC 50 s. The differential effect of CQRRAs in P. falciparum and P. vivax suggests significant differences in CQ kinetics and, potentially, the likely mechanism of CQ resistance between these two species. © Crown copyright 2017.

Implications of Parasites Lacking Plasmodium falciparum Histidine-Rich Protein 2 on Malaria Morbidity and Control When Rapid Diagnostic Tests Are Used for Diagnosis.

PubMed

Gatton, Michelle L; Dunn, Jessica; Chaudhry, Alisha; Ciketic, Sadmir; Cunningham, Jane; Cheng, Qin

2017-04-01

Rapid diagnostic tests (RDTs) are an important tool for malaria diagnosis, with most using antibodies against Plasmodium falciparum histidine-rich protein 2 (PfHRP2). Reports of P. falciparum lacking this protein are increasing, creating a problem for diagnosis of falciparum malaria in locations without quality-assured microscopy. An agent-based stochastic simulation model of P. falciparum transmission was used to investigate the selective pressure exerted on parasite populations by use of RDTs for diagnosis of symptomatic cases. The model considered parasites with normal, reduced, or no PfHRP2, and diagnosis using PfHRP2-only or combination RDTs. Use of PfHRP2-only RDTs in communities where a PfHRP2-negative parasite was introduced during the simulation resulted in transmission of the parasite in >80% of cases, compared with <30% for normal or PfHRP2-reduced parasites. Using PfHRP2-only RDTs in the presence of PfHRP2-negative parasites caused an increase in prevalence, reduced RDT positivity within symptomatic patients but no change in the number of antimalarial treatments due to false-negative RDT results. Diagnosis with PfHRP2/Pf-Plasmodium lactate dehydrogenase combination RDTs did not select for PfHRP2-negative parasites. The use of PfHRP2-only RDTs is sufficient to select P. falciparum parasites lacking this protein, thus posing a significant public health problem, which could be moderated by using PfHRP2/Pf-Plasmodium lactate dehydrogenase combination RDTs. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Deaths due to Plasmodium knowlesi malaria in Sabah, Malaysia: association with reporting as Plasmodium malariae and delayed parenteral artesunate

PubMed Central

2012-01-01

Background The simian parasite Plasmodium knowlesi is recognized as a common cause of severe and fatal human malaria in Sabah, Malaysia, but is morphologically indistinguishable from and still commonly reported as Plasmodium malariae, despite the paucity of this species in Sabah. Since December 2008 Sabah Department of Health has recommended intravenous artesunate and referral to a general hospital for all severe malaria cases of any species. This paper reviews all malaria deaths in Sabah subsequent to the introduction of these measures. Reporting of malaria deaths in Malaysia is mandatory. Methods Details of reported malaria deaths during 2010-2011 were reviewed to determine the proportion of each Plasmodium species. Demographics, clinical presentations and management of severe malaria caused by each species were compared. Results Fourteen malaria deaths were reported, comprising seven Plasmodium falciparum, six P. knowlesi and one Plasmodium vivax (all PCR-confirmed). Of the six P. knowlesi deaths, five were attributable to knowlesi malaria and one was attributable to P. knowlesi-associated enterobacter sepsis. Patients with directly attributable P. knowlesi deaths (N = 5) were older than those with P. falciparum (median age 51 [IQR 50-65] vs 22 [IQR 9-55] years, p = 0.06). Complications in fatal P. knowlesi included respiratory distress (N = 5, 100%), hypotension (N = 4, 80%), and renal failure (N = 4, 80%). All patients with P. knowlesi were reported as P. malariae by microscopy. Only two of five patients with severe knowlesi malaria on presentation received immediate parenteral anti-malarial treatment. The patient with P. vivax-associated severe illness did not receive parenteral treatment. In contrast six of seven patients with severe falciparum malaria received immediate parenteral treatment. Conclusion Plasmodium knowlesi was responsible, either directly or through gram-negative bacteraemia, for almost half of malaria deaths in Sabah. Patients with severe non-falciparum malaria were less likely to receive immediate parenteral therapy. This highlights the need in Sabah for microscopically diagnosed P. malariae to be reported as P. knowlesi to improve recognition and management of this potentially fatal species. Clinicians need to be better informed of the potential for severe and fatal malaria from non-falciparum species, and the need to treat all severe malaria with immediate intravenous artesunate. PMID:22905799

High prevalence of malaria in a non-endemic setting: comparison of diagnostic tools and patient outcome during a four-year survey (2013-2017).

PubMed

Calderaro, Adriana; Piccolo, Giovanna; Montecchini, Sara; Buttrini, Mirko; Rossi, Sabina; Dell'Anna, Maria Loretana; De Remigis, Valeria; Arcangeletti, Maria Cristina; Chezzi, Carlo; De Conto, Flora

2018-02-05

Malaria is no longer endemic in Italy since 1970 when the World Health Organization declared Italy malaria-free, but it is now the most commonly imported disease. The aim of the study was to analyse the trend of imported malaria cases in Parma, Italy, during January 2013-June 2017, reporting also the treatment and the outcome of cases, exploring the comparison of the three diagnostic tests used for malaria diagnosis: microscopy, immunochromatographic assay (ICT) (BinaxNOW ® ) and Real-time PCR assays detecting Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale curtisi, Plasmodium ovale wallikeri, and Plasmodium knowlesi. Of the 288 patients with suspected malaria, 87 were positive by microscopy: 73 P. falciparum, 2 P. vivax, 8 P. ovale, 1 P. vivax/P. ovale, 1 P. malariae and 2 Plasmodium sp. All samples were positive by ICT except 6. Plasmodial DNA was revealed in the 87 cases and in 2 additional cases showing P. falciparum-specific bands by ICT, as follows: 75 P. falciparum, 2 P. vivax, 6 P. ovale curtisi, 3 P. ovale wallikeri, 1 P. malariae, and 2 mixed infections. 72 patients were foreigners and 17 Italians travelling for tourism or business. The majority of these patients presented with fever at blood collection and did not have chemoprophylaxis. No fatal cases were observed and the drug mostly used was quinine observing a negative blood smear or a parasitaemia < 0.001% after 48-72 h' therapy. The study shows an update and a thorough analysis of imported malaria cases in the area of Parma during 4.5 years from the point of view of the total case management, clinical and diagnostic. The prevalence of malaria in such area in the considered period was especially due to immigrants mostly from Africa. Molecular methods were more sensitive and specific than microscopy and ICT, both detecting additional cases of P. falciparum malaria missed by microscopy and correctly identifying the Plasmodium species of medical interest. The data reported in this study may stimulate the clinicians in non-endemic areas to suspect malaria also in cases, where the most typical symptoms are absent, and the parasitologists to confirm the results of microscopy, remaining the reference method, with molecular methods to avoid misdiagnosis.

Mitochondrial DNA from the eradicated European Plasmodium vivax and P. falciparum from 70-year-old slides from the Ebro Delta in Spain

PubMed Central

Gelabert, Pere; Sandoval-Velasco, Marcela; Olalde, Iñigo; Fregel, Rosa; Rieux, Adrien; Escosa, Raül; Aranda, Carles; Paaijmans, Krijn; Mueller, Ivo; Gilbert, M. Thomas P.; Lalueza-Fox, Carles

2016-01-01

Phylogenetic analysis of Plasmodium parasites has indicated that their modern-day distribution is a result of a series of human-mediated dispersals involving transport between Africa, Europe, America, and Asia. A major outstanding question is the phylogenetic affinity of the malaria causing parasites Plasmodium vivax and falciparum in historic southern Europe—where it was endemic until the mid-20th century, after which it was eradicated across the region. Resolving the identity of these parasites will be critical for answering several hypotheses on the malaria dispersal. Recently, a set of slides with blood stains of malaria-affected people from the Ebro Delta (Spain), dated between 1942 and 1944, have been found in a local medical collection. We extracted DNA from three slides, two of them stained with Giemsa (on which Plasmodium parasites could still be seen under the microscope) and another one consisting of dried blood spots. We generated the data using Illumina sequencing after using several strategies aimed at increasing the Plasmodium DNA yield: depletion of the human genomic (g)DNA content through hybridization with human gDNA baits, and capture-enrichment using gDNA derived from P. falciparum. Plasmodium mitochondrial genome sequences were subsequently reconstructed from the resulting data. Phylogenetic analysis of the eradicated European P. vivax mtDNA genome indicates that the European isolate is closely related to the most common present-day American haplotype and likely entered the American continent post-Columbian contact. Furthermore, the European P. falciparum mtDNA indicates a link with current Indian strains that is in agreement with historical accounts. PMID:27671660

Plasmodium knowlesi Skeleton-Binding Protein 1 Localizes to the 'Sinton and Mulligan' Stipplings in the Cytoplasm of Monkey and Human Erythrocytes.

PubMed

Lucky, Amuza Byaruhanga; Sakaguchi, Miako; Katakai, Yuko; Kawai, Satoru; Yahata, Kazuhide; Templeton, Thomas J; Kaneko, Osamu

2016-01-01

The malaria parasite, Plasmodium, exports protein products to the infected erythrocyte to introduce modifications necessary for the establishment of nutrient acquisition and surface display of host interaction ligands. Erythrocyte remodeling impacts parasite virulence and disease pathology and is well documented for the human malaria parasite Plasmodium falciparum, but has been less described for other Plasmodium species. For P. falciparum, the exported protein skeleton-binding protein 1 (PfSBP1) is involved in the trafficking of erythrocyte surface ligands and localized to membranous structures within the infected erythrocyte, termed Maurer's clefts. In this study, we analyzed SBP1 orthologs across the Plasmodium genus by BLAST analysis and conserved gene synteny, which were also recently described by de Niz et al. (2016). To evaluate the localization of an SBP1 ortholog, we utilized the zoonotic malaria parasite, Plasmodium knowlesi. Immunofluorescence assay of transgenic P. knowlesi parasites expressing epitope-tagged recombinant PkSBP1 revealed a punctate staining pattern reminiscent of Maurer's clefts, following infection of either monkey or human erythrocytes. The recombinant PkSBP1-positive puncta co-localized with Giemsa-stained structures, known as 'Sinton and Mulligan' stipplings. Immunoelectron microscopy also showed that recombinant PkSBP1 localizes within or on the membranous structures akin to the Maurer's clefts. The recombinant PkSBP1 expressed in P. falciparum-infected erythrocytes co-localized with PfSBP1 at the Maurer's clefts, indicating an analogous trafficking pattern. A member of the P. knowlesi 2TM protein family was also expressed and localized to membranous structures in infected monkey erythrocytes. These results suggest that the trafficking machinery and induced erythrocyte cellular structures of P. knowlesi are similar following infection of both monkey and human erythrocytes, and are conserved with P. falciparum.

Mitochondrial DNA from the eradicated European Plasmodium vivax and P. falciparum from 70-year-old slides from the Ebro Delta in Spain.

PubMed

Gelabert, Pere; Sandoval-Velasco, Marcela; Olalde, Iñigo; Fregel, Rosa; Rieux, Adrien; Escosa, Raül; Aranda, Carles; Paaijmans, Krijn; Mueller, Ivo; Gilbert, M Thomas P; Lalueza-Fox, Carles

2016-10-11

Phylogenetic analysis of Plasmodium parasites has indicated that their modern-day distribution is a result of a series of human-mediated dispersals involving transport between Africa, Europe, America, and Asia. A major outstanding question is the phylogenetic affinity of the malaria causing parasites Plasmodium vivax and falciparum in historic southern Europe-where it was endemic until the mid-20th century, after which it was eradicated across the region. Resolving the identity of these parasites will be critical for answering several hypotheses on the malaria dispersal. Recently, a set of slides with blood stains of malaria-affected people from the Ebro Delta (Spain), dated between 1942 and 1944, have been found in a local medical collection. We extracted DNA from three slides, two of them stained with Giemsa (on which Plasmodium parasites could still be seen under the microscope) and another one consisting of dried blood spots. We generated the data using Illumina sequencing after using several strategies aimed at increasing the Plasmodium DNA yield: depletion of the human genomic (g)DNA content through hybridization with human gDNA baits, and capture-enrichment using gDNA derived from P. falciparum Plasmodium mitochondrial genome sequences were subsequently reconstructed from the resulting data. Phylogenetic analysis of the eradicated European P. vivax mtDNA genome indicates that the European isolate is closely related to the most common present-day American haplotype and likely entered the American continent post-Columbian contact. Furthermore, the European P. falciparum mtDNA indicates a link with current Indian strains that is in agreement with historical accounts.

The evolution and diversity of a low complexity vaccine candidate, merozoite surface protein 9 (MSP-9), in Plasmodium vivax and closely related species.

PubMed

Chenet, Stella M; Pacheco, M Andreína; Bacon, David J; Collins, William E; Barnwell, John W; Escalante, Ananias A

2013-12-01

The merozoite surface protein-9 (MSP-9) has been considered a target for an anti-malarial vaccine since it is one of many proteins involved in the erythrocyte invasion, a critical step in the parasite life cycle. Orthologs encoding this antigen have been found in all known species of Plasmodium parasitic to primates. In order to characterize and investigate the extent and maintenance of MSP-9 genetic diversity, we analyzed DNA sequences of the following malaria parasite species: Plasmodium falciparum, Plasmodium reichenowi, Plasmodium chabaudi, Plasmodium yoelii, Plasmodium berghei, Plasmodium coatneyi, Plasmodium gonderi, Plasmodium knowlesi, Plasmodium inui, Plasmodium simiovale, Plasmodium fieldi, Plasmodium cynomolgi and Plasmodium vivax and evaluated the signature of natural selection in all MSP-9 orthologs. Our findings suggest that the gene encoding MSP-9 is under purifying selection in P. vivax and closely related species. We further explored how selection affected different regions of MSP-9 by comparing the polymorphisms in P. vivax and P. falciparum, and found contrasting patterns between these two species that suggest differences in functional constraints. This observation implies that the MSP-9 orthologs in human parasites may interact differently with the host immune response. Thus, studies carried out in one species cannot be directly translated into the other. Copyright © 2013 Elsevier B.V. All rights reserved.

On Programmed Cell Death in Plasmodium falciparum: Status Quo

PubMed Central

Engelbrecht, Dewaldt; Durand, Pierre Marcel; Coetzer, Thérèsa Louise

2012-01-01

Conflicting arguments and results exist regarding the occurrence and phenotype of programmed cell death (PCD) in the malaria parasite Plasmodium falciparum. Inconsistencies relate mainly to the number and type of PCD markers assessed and the different methodologies used in the studies. In this paper, we provide a comprehensive overview of the current state of knowledge and empirical evidence for PCD in the intraerythrocytic stages of P. falciparum. We consider possible reasons for discrepancies in the data and offer suggestions towards more standardised investigation methods in this field. Furthermore, we present genomic evidence for PCD machinery in P. falciparum. We discuss the potential adaptive or nonadaptive role of PCD in the parasite life cycle and its possible exploitation in the development of novel drug targets. Lastly, we pose pertinent unanswered questions concerning the PCD phenomenon in P. falciparum to provide future direction. PMID:22287973

The efficiency of sporozoite transmission in the human malarias, Plasmodium falciparum and P. vivax*

PubMed Central

Burkot, T. R.; Graves, P. M.; Cattan, J. A.; Wirtz, R. A.; Gibson, F. D.

1987-01-01

Reported are malaria sporozoite and inoculation rates over a 1-year period in eight epidemiologically defined villages of different endemicity in Madang Province, Papua New Guinea. In the study, more than 41 000 wild-caught mosquitos were analysed for Plasmodium falciparum and P. vivax sporozoites by ELISA. In a given village the entomological inoculation rates correlated strongly with the prevalences of both these malarial parasites in children. However, the prevalence of P. falciparum infections in children was much higher than that of P. vivax, despite similar inoculation rates for the two species. These data suggest that in Papua New Guinea P. falciparum is more efficiently transmitted than P. vivax from mosquito to man. The increased efficiency of transmission of P. falciparum may be due to the heavier sporozoite densities in wild-caught mosquitos naturally infected with P. falciparum sporozoites that were tenfold greater than the sporozoite densities in mosquitos infected with P. vivax. PMID:3311441

Evolution of genetic polymorphisms of Plasmodium falciparum merozoite surface protein (PfMSP) in Thailand.

PubMed

Kuesap, Jiraporn; Chaijaroenkul, Wanna; Ketprathum, Kanchanok; Tattiyapong, Puntanat; Na-Bangchang, Kesara

2014-02-01

Plasmodium falciparum malaria is a major public health problem in Thailand due to the emergence of multidrug resistance. The understanding of genetic diversity of malaria parasites is essential for developing effective drugs and vaccines. The genetic diversity of the merozoite surface protein-1 (PfMSP-1) and merozoite surface protein-2 (PfMSP-2) genes was investigated in a total of 145 P. falciparum isolates collected from Mae Sot District, Tak Province, Thailand during 3 different periods (1997-1999, 2005-2007, and 2009-2010). Analysis of genetic polymorphisms was performed to track the evolution of genetic change of P. falciparum using PCR. Both individual genes and their combination patterns showed marked genetic diversity during the 3 study periods. The results strongly support that P. falciparum isolates in Thailand are markedly diverse and patterns changed with time. These 2 polymorphic genes could be used as molecular markers to detect multiple clone infections and differentiate recrudescence from reinfection in P. falciparum isolates in Thailand.

Select pyrimidinones inhibit the propagation of the malarial parasite, Plasmodium falciparum

PubMed Central

Chiang, Annette N.; Valderramos, Juan-Carlos; Balachandran, Raghavan; Chovatiya, Raj J.; Mead, Brian P.; Schneider, Corinne; Bell, Samantha L.; Klein, Michael G.; Huryn, Donna M.; Chen, Xiaojiang S.; Day, Billy W.; Fidock, David A.; Wipf, Peter; Brodsky, Jeffrey L.

2009-01-01

Plasmodium falciparum, the Apicomplexan parasite that is responsible for the most lethal forms of human malaria, is exposed to radically different environments and stress factors during its complex lifecycle. In any organism, Hsp70 chaperones are typically associated with tolerance to stress. We therefore reasoned that inhibition of P. falciparum Hsp70 chaperones would adversely affect parasite homeostasis. To test this hypothesis, we measured whether pyrimidinone-amides, a new class of Hsp70 modulators, could inhibit the replication of the pathogenic P. falciparum stages in human red blood cells. Nine compounds with IC50 values from 30 nM to 1.6 μM were identified. Each compound also altered the ATPase activity of purified P. falciparum Hsp70 in single-turnover assays, although higher concentrations of agents were required than was necessary to inhibit P. falciparum replication. Varying effects of these compounds on Hsp70s from other organisms were also observed. Together, our data indicate that pyrimidinone-amides constitute a novel class of anti-malarial agents. PMID:19195901

Refrigeration provides a simple means to synchronize in vitro cultures of Plasmodium falciparum.

PubMed

Yuan, Lili; Hao, Mingming; Wu, Lanou; Zhao, Zhen; Rosenthal, Benjamin M; Li, Xiaomei; He, Yongshu; Sun, Ling; Feng, Guohua; Xiang, Zheng; Cui, Liwang; Yang, Zhaoqing

2014-05-01

Plasmodium falciparum is usually asynchronous during in vitro culture. Highly synchronized cultures of P. falciparum are routinely used in malaria research. Here, we describe a simple synchronization procedure for P. falciparum asexual erythrocytic culture, which involves storage at 4°C for 8-24 h followed by routine culture. When cultures with 27-60% of ring stage were synchronized using this procedure, 70-93% ring stages were obtained after 48 h of culture and relative growth synchrony remained for at least two erythrocytic cycles. To test the suitability of this procedure for subsequent work, drug sensitivity assays were performed using four laboratory strains and four freshly adapted clinical P. falciparum isolates. Parasites synchronized by sorbitol treatment or refrigeration showed similar dose-response curves and comparable IC50 values to four antimalarial drugs. The refrigeration synchronization method is simple, inexpensive, time-saving, and should be especially useful when large numbers of P. falciparum culture are handled. Copyright © 2014 Elsevier Inc. All rights reserved.

Open-label, randomized, non-inferiority clinical trial of artesunate-amodiaquine versus artemether-lumefantrine fixed-dose combinations in children and adults with uncomplicated falciparum malaria in Côte d'Ivoire.

PubMed

Toure, Offianan A; Assi, Serge B; N'Guessan, Tiacoh L; Adji, Gbessi E; Ako, Aristide B; Brou, Marie J; Ehouman, Marie F; Gnamien, Laeticia A; Coulibaly, M'Lanhoro A A; Coulibaly, Baba; Beourou, Sylvain; Bassinka, Issiaka; Soumahoro, Adama; Kadjo, Florence; Tano, Mea A

2014-11-19

Emergence of artemisinin resistance has raised concerns that the most potent anti-malarial drug may be under threat. Artesunate-amodiaquine (AS-AQ) and artemether-lumefantrine (AL) are, respectively, the first- and second-line treatments for uncomplicated falciparum malaria in Côte d'Ivoire. Constant monitoring by National Malaria Control Programme (NMCP) of drug efficacy is an important tool in establishing rational anti-malarial drug policies in Côte d'Ivoire. In an open label, randomized controlled clinical trial, children and adults were randomized to receive AS-AQ or AL. Both drug regimens were given for three days, and follow-up was for 42 days. The primary endpoint was the 42-day cure rate and was defined as proportion of patients with PCR-corrected cure rate after 42 days of follow-up. A total of 383 patients who were attending the Anonkoua-koute (Abidjan), Petit Paris (Korhogo) and Libreville (Man) hospitals and presenting with symptomatic acute uncomplicated falciparum malaria were randomized to receive AS-AQ (188) and AL (195). The intention-to-treat analysis showed effectiveness rates of 94.7% and 96.4% for AS-AQ and AL, respectively on day 42. After adjustment for PCR, these rates were 96.8% and 99%, respectively. At day 42, in per-protocol analysis, Adequate clinical and parasitological response (ACPR) PCR uncorrected was 97.8% and 97.4% for AS-AQ and AL, respectively. The PCR adjusted ACPR was 100% for each combination and both regimens were well tolerated. This study has shown the high efficacy of AS-AQ in patients of all ages with acute uncomplicated falciparum malaria and AS-AQ was non-inferior to AL. Continuous efficacy monitoring is recommended.

The Hsp40 proteins of Plasmodium falciparum and other apicomplexa: regulating chaperone power in the parasite and the host.

PubMed

Botha, M; Pesce, E-R; Blatch, G L

2007-01-01

Extensive structural and functional remodelling of Plasmodium falciparum (malaria)-infected erythrocytes follows the export of a range of proteins of parasite origin (exportome) across the parasitophorous vacuole into the host erythrocyte. The genome of P. falciparum encodes a diverse chaperone complement including at least 43 members of the heat shock protein 40kDa (Hsp40) family, and six members of the heat shock protein 70kDa (Hsp70) family. Nearly half of the Hsp40 proteins of P. falciparum are predicted to contain a PEXEL/HT (Plasmodium export element/host targeting signal) sequence motif, and hence are likely to be part of the exportome. In this review we critically evaluate the classification, sequence similarity and clustering, and possible interactors of the P. falciparum Hsp40 chaperone machinery. In addition to the types I, II and III Hsp40 proteins all exhibiting the signature J-domain, the P. falciparum genome also encodes a number of specialized Hsp40 proteins with a J-like domain, which we have categorized as type IV Hsp40 proteins. Analysis of the potential P. falciparum Hsp40 protein interaction network revealed connections predominantly with cytoskeletal and membrane proteins, transcriptional machinery, DNA repair and replication machinery, translational machinery, the proteasome and proteolytic enzymes, and enzymes involved in cellular physiology. Comparison of the Hsp40 proteins of P. falciparum to those of other apicomplexa reveals that most of the proteins (especially the PEXEL/HT-containing proteins) are unique to P. falciparum. Furthermore, very few of the P. falciparum Hsp40 proteins have human homologs, except for those proteins implicated in fundamental biological processes. Our analysis suggests that P. falciparum has evolved an expanded and specialized Hsp40 protein machinery to enable it successfully to invade and remodel the human erythrocyte, and we propose a model in which these proteins are involved in chaperone-mediated translocation, folding, assembly and regulation of parasite and host proteins.

The Exported Chaperone PfHsp70x Is Dispensable for the Plasmodium falciparum Intraerythrocytic Life Cycle.

PubMed

Cobb, David W; Florentin, Anat; Fierro, Manuel A; Krakowiak, Michelle; Moore, Julie M; Muralidharan, Vasant

2017-01-01

Export of parasite proteins into the host erythrocyte is essential for survival of Plasmodium falciparum during its asexual life cycle. While several studies described key factors within the parasite that are involved in protein export, the mechanisms employed to traffic exported proteins within the host cell are currently unknown. Members of the Hsp70 family of chaperones, together with their Hsp40 cochaperones, facilitate protein trafficking in other organisms, and are thus likely used by P. falciparum in the trafficking of its exported proteins. A large group of Hsp40 proteins is encoded by the parasite and exported to the host cell, but only one Hsp70, P. falciparum Hsp70x (PfHsp70x), is exported with them. PfHsp70x is absent in most Plasmodium species and is found only in P. falciparum and closely related species that infect apes. Herein, we have utilized clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 genome editing in P. falciparum to investigate the essentiality of PfHsp70x. We show that parasitic growth was unaffected by knockdown of PfHsp70x using both the dihydrofolate reductase (DHFR)-based destabilization domain and the glmS ribozyme system. Similarly, a complete gene knockout of PfHsp70x did not affect the ability of P. falciparum to proceed through its intraerythrocytic life cycle. The effect of PfHsp70x knockdown/knockout on the export of proteins to the host red blood cell (RBC), including the critical virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1), was tested, and we found that this process was unaffected. These data show that although PfHsp70x is the sole exported Hsp70, it is not essential for the asexual development of P. falciparum . IMPORTANCE Half of the world's population lives at risk for malaria. The intraerythrocytic life cycle of Plasmodium spp. is responsible for clinical manifestations of malaria; therefore, knowledge of the parasite's ability to survive within the erythrocyte is needed to combat the deadliest agent of malaria, P. falciparum . An outstanding question in the field is how P. falciparum undertakes the essential process of trafficking its proteins within the host cell. In most organisms, chaperones such as Hsp70 are employed in protein trafficking. Of the Plasmodium species causing human disease, the chaperone PfHsp70x is unique to P. falciparum , and it is the only parasite protein of its kind exported to the host (S. Külzer et al., Cell Microbiol 14:1784-1795, 2012). This has placed PfHsp70x as an ideal target to inhibit protein trafficking and kill the parasite. However, we show that PfHsp70x is not required for export of parasite effectors and it is not essential for parasite survival inside the RBC.

Overview of the improvement of the ring-stage survival assay-a novel phenotypic assay for the detection of artemisinin-resistant Plasmodium falciparum.

PubMed

Zhang, Jie; Feng, Guo-Hua; Zou, Chun-Yan; Su, Pin-Can; Liu, Huai-E; Yang, Zhao-Qing

2017-11-18

Artemisinin resistance in Plasmodium falciparum threatens the remarkable efficacy of artemisinin-based combination therapies worldwide. Thus, greater insight into the resistance mechanism using monitoring tools is essential. The ring-stage survival assay is used for phenotyping artemisinin-resistance or decreased artemisinin sensitivity. Here, we review the progress of this measurement assay and explore its limitations and potential applications.

Expression, Extracellular Secretion, and Immunogenicity of the Plasmodium falciparum Sporozoite Surface Protein 2 in Salmonella Vaccine Strains

PubMed Central

Gómez-Duarte, Oscar G.; Pasetti, Marcela F.; Santiago, Araceli; Sztein, Marcelo B.; Hoffman, Stephen L.; Levine, Myron M.

2001-01-01

Deleting transmembrane α-helix motifs from Plasmodium falciparum sporozoite surface protein (SSP-2) allowed its secretion from Salmonella enterica serovar Typhimurium SL3261 and S. enterica serovar Typhi CVD 908-htrA by the Hly type I secretion system. In mice immunized intranasally, serovar Typhimurium constructs secreting SSP-2 stimulated greater gamma interferon splenocyte responses than did nonsecreting constructs (P = 0.04). PMID:11160021

Novel 2-Phenoxyanilide Congeners Derived from a Hit Structure of the TCAMS: Synthesis and Evaluation of Their in Vitro Activity against Plasmodium falciparum.

PubMed

Weidner, Thomas; Nasereddin, Abed; Preu, Lutz; Grünefeld, Johann; Dzikowski, Ron; Kunick, Conrad

2016-02-17

The Tres Cantos Antimalarial Compound Set (TCAMS) is a publicly available compound library which contains 13533 hit structures with confirmed activity against Plasmodium falciparum, the infective agent responsible for malaria tropica. The TCAMS provides a variety of starting points for the investigation of new antiplasmodial drug leads. One of the promising compounds is TCMDC-137332, which seemed to be a good starting point due to its antiplasmodial potency and its predicted physicochemical properties. Several new analogues based on a 2-phenoxyanilide scaffold were synthesized by standard amide coupling reactions and were fully characterized regarding their identity and purity by spectroscopic and chromatographic methods. Furthermore, the results of the biological evaluation of all congeners against Plasmodium falciparum NF54 strains are presented. The findings of our in vitro screening could not confirm the presumed nanomolar antiplasmodial activity of TCMDC-137332 and its derivatives.

Antimalarial activity of three Pakistani medicinal plants.

PubMed

Irshad, Saba; Mannan, Abdul; Mirza, Bushra

2011-10-01

This study was conducted to determine the in vitro anti-malarial activity of three medicinal plants, Picrorhiza kurroa, Caesalpinia bonducella and Artemisia absinthium of Pakistan. Different extracts of various parts of these plants were prepared by maceration and percolation, and were evaluated for their antimalarial activity. Aqueous, cold alcoholic and hot alcoholic extracts of Picrorhiza kurroa showed 34%, 100% and 90% inhibition in growth of Plasmodium falciparum, respectively, at 2.00 mg/ml. While aqueous, cold alcoholic and hot alcoholic extracts of Caesalpinia bonducella showed 65%, 56% and 76% inhibition in growth of Plasmodium falciparum, respectively at same concentrations. In the case of Artemisia absinthium, aqueous, cold alcoholic and hot alcoholic extract of Artemisia absinthium showed 35%, 55% and 21% inhibition in growth of Plasmodium falciparum, respectively at 2.00 mg/ml. In our study, extracts of Picrorhiza kurroa were found good for traditional therapy with highly significant results.

Challenges of assessing the clinical efficacy of asexual blood-stage Plasmodium falciparum malaria vaccines.

PubMed

Sheehy, Susanne H; Douglas, Alexander D; Draper, Simon J

2013-09-01

In the absence of any highly effective vaccine candidate against Plasmodium falciparum malaria, it remains imperative for the field to pursue all avenues that may lead to the successful development of such a formulation. The development of a subunit vaccine targeting the asexual blood-stage of Plasmodium falciparum malaria infection has proven particularly challenging with only limited success to date in clinical trials. However, only a fraction of potential blood-stage vaccine antigens have been evaluated as targets, and a number of new promising candidate antigen formulations and delivery platforms are approaching clinical development. It is therefore essential that reliable and sensitive methods of detecting, or ruling out, even modest efficacy of blood-stage vaccines in small clinical trials be established. In this article we evaluate the challenges facing blood-stage vaccine developers, assess the appropriateness and limitations of various in vivo approaches for efficacy assessment and suggest future directions for the field.

Flow cytometry as a tool for analyzing changes in Plasmodium falciparum cell cycle following treatment with indol compounds.

PubMed

Schuck, Desirée Cigaran; Ribeiro, Ramira Yuri; Nery, Arthur A; Ulrich, Henning; Garcia, Célia R S

2011-11-01

Melatonin and its derivatives modulate the Plasmodium falciparum and Plasmodium chabaudi cell cycle. Flow cytometry was employed together with the nucleic acid dye YOYO-1 allowing precise discrimination between mono- and multinucleated forms of P. falciparum-infected red blood cell. The use of YOYO-1 permitted excellent discrimination between uninfected and infected red blood cells as well as between early and late parasite stages. Fluorescence intensities of schizont-stage parasites were about 10-fold greater than those of ring-trophozoite form parasites. Melatonin and related indolic compounds including serotonin, N-acetyl-serotonin and tryptamine induced an increase in the percentage of multinucleated forms compared to non-treated control cultures. YOYO-1 staining of infected erythrocyte and subsequent flow cytometry analysis provides a powerful tool in malaria research for screening of bioactive compounds. Copyright © 2011 International Society for Advancement of Cytometry.

Simultaneous detection of Plasmodium vivax and Plasmodium falciparum gametocytes in clinical isolates by multiplex-nested RT-PCR

PubMed Central

2012-01-01

Background Gametocyte carriage is essential for malaria transmission and endemicity of disease; thereby it is a target for malaria control strategies. Malaria-infected individuals may harbour gametocytes below the microscopic detection threshold that can be detected by reverse transcription polymerase chain reaction (RT-PCR) targeting gametocyte-specific mRNA. To date, RT-PCR has mainly been applied to the diagnosis of Plasmodium falciparum gametocytes but very limited for that of Plasmodium vivax. Methods A multiplex-nested RT-PCR targeting Pfs25 and Pvs25 mRNA specific to mature gametocytes of P. falciparum and P. vivax, respectively, was developed. The assay was evaluated using blood samples collected in rainy and dry seasons from febrile patients,in a malaria-endemic area in Thailand. Malaria diagnosis was performed by Giemsa-stained blood smears and 18S rRNA PCR. Results The multiplex-nested RT-PCR detected Pfs25 mRNA in 75 of 86 (87.2%) P. falciparum-infected individuals and Pvs25 mRNA in 82 of 90 (91.1%) P. vivax malaria patients diagnosed by 18S rRNA PCR. Gametocytes were detected in 38 (eight P. falciparum and 30 P. vivax) of 157 microscopy positive samples, implying that a large number of patients harbour sub-microscopic gametocytaemia. No seasonal differences in gametocyte carriage were observed for both malaria species diagnosed by multiplex-nested RT-PCR. With single-nested RT-PCR targeting Pfs25 or Pvs25 mRNA as standard, the multiplex-nested RT-PCR offered sensitivities of 97.4% and 98.9% and specificities of 100% and 98.8% for diagnosing mature gametocytes of P. falciparum and P. vivax, respectively. The minimum detection limit of the multiplex-nested PCR was 10 copies of templates. Conclusions The multiplex-nested RT-PCR developed herein is useful for simultaneous assessment of both P. falciparum and P. vivax gametocyte carriage that is prevalent and generally sympatric in several malaria-endemic areas outside Africa. PMID:22682065

Simultaneous detection of Plasmodium vivax and Plasmodium falciparum gametocytes in clinical isolates by multiplex-nested RT-PCR.

PubMed

Kuamsab, Napaporn; Putaporntip, Chaturong; Pattanawong, Urassaya; Jongwutiwes, Somchai

2012-06-10

Gametocyte carriage is essential for malaria transmission and endemicity of disease; thereby it is a target for malaria control strategies. Malaria-infected individuals may harbour gametocytes below the microscopic detection threshold that can be detected by reverse transcription polymerase chain reaction (RT-PCR) targeting gametocyte-specific mRNA. To date, RT-PCR has mainly been applied to the diagnosis of Plasmodium falciparum gametocytes but very limited for that of Plasmodium vivax. A multiplex-nested RT-PCR targeting Pfs25 and Pvs25 mRNA specific to mature gametocytes of P. falciparum and P. vivax, respectively, was developed. The assay was evaluated using blood samples collected in rainy and dry seasons from febrile patients,in a malaria-endemic area in Thailand. Malaria diagnosis was performed by Giemsa-stained blood smears and 18S rRNA PCR. The multiplex-nested RT-PCR detected Pfs25 mRNA in 75 of 86 (87.2%) P. falciparum-infected individuals and Pvs25 mRNA in 82 of 90 (91.1%) P. vivax malaria patients diagnosed by 18S rRNA PCR. Gametocytes were detected in 38 (eight P. falciparum and 30 P. vivax) of 157 microscopy positive samples, implying that a large number of patients harbour sub-microscopic gametocytaemia. No seasonal differences in gametocyte carriage were observed for both malaria species diagnosed by multiplex-nested RT-PCR. With single-nested RT-PCR targeting Pfs25 or Pvs25 mRNA as standard, the multiplex-nested RT-PCR offered sensitivities of 97.4% and 98.9% and specificities of 100% and 98.8% for diagnosing mature gametocytes of P. falciparum and P. vivax, respectively. The minimum detection limit of the multiplex-nested PCR was 10 copies of templates. The multiplex-nested RT-PCR developed herein is useful for simultaneous assessment of both P. falciparum and P. vivax gametocyte carriage that is prevalent and generally sympatric in several malaria-endemic areas outside Africa.

Evaluation of SYBR green I based visual loop-mediated isothermal amplification (LAMP) assay for genus and species-specific diagnosis of malaria in P. vivax and P. falciparum endemic regions.

PubMed

Singh, Ruchi; Singh, Dhirendra Pratap; Savargaonkar, Deepali; Singh, Om P; Bhatt, Rajendra M; Valecha, Neena

2017-01-01

Loop-mediated isothermal amplification (LAMP) is an emerging nucleic acid based diag- nostic approach that is easily adaptable to the field settings with limited technical resources. This study was aimed to evaluate the LAMP assay for the detection and identification of Plasmodium falciparum and P. vivax infection in malaria suspected cases using genus and species-specific assay. The 18S rRNA-based LAMP assay was evaluated for diagnosis of genus Plasmodium, and species- specific diagnosis of P. falciparum and P. vivax, infection employing 317 malaria suspected cases, and the results were compared with those obtained by 18S nested PCR (n-PCR). All the samples were confirmed by microscopy for the presence of Plasmodium parasite. The n-PCR was positive in all Plasmodium-infected cases (n=257; P. falciparum=133; P. vivax=124) and negative in microscopy negative cases (n=58) except for two cases which were positive for P. vivax, giving a sen- sitivity of 100% (95% CI: 97.04-100%) and a specificity of 100% (95% CI: 88.45-99.5%). Genus-specific LAMP assay missed 11 (3.2%) microscopy and n-PCR confirmed vivax malaria cases. Considering PCR results as a refer- ence, LAMP was 100% sensitive and specific for P. falciparum, whereas it exhibited 95.16% sensitivity and 96.7% specificity for P. vivax. The n-PCR assay detected 10 mixed infection cases while species-specific LAMP detected five mixed infection cases of P. vivax and P. falciparum, which were not detected by microscopy. Genus-specific LAMP assay displayed low sensitivity. Falciparum specific LAMP assay displayed high sensitivity whereas vivax specific LAMP assay displayed low sensitivity. Failed detection of vivax cases otherwise confirmed by the n-PCR assay indicates exploitation of new targets and improved detection methods to attain 100% results for P. vivax detection.

DNA Repair Mechanisms and Their Biological Roles in the Malaria Parasite Plasmodium falciparum

PubMed Central

Lee, Andrew H.; Symington, Lorraine S.

2014-01-01

SUMMARY Research into the complex genetic underpinnings of the malaria parasite Plasmodium falciparum is entering a new era with the arrival of site-specific genome engineering. Previously restricted only to model systems but now expanded to most laboratory organisms, and even to humans for experimental gene therapy studies, this technology allows researchers to rapidly generate previously unattainable genetic modifications. This technological advance is dependent on DNA double-strand break repair (DSBR), specifically homologous recombination in the case of Plasmodium. Our understanding of DSBR in malaria parasites, however, is based largely on assumptions and knowledge taken from other model systems, which do not always hold true in Plasmodium. Here we describe the causes of double-strand breaks, the mechanisms of DSBR, and the differences between model systems and P. falciparum. These mechanisms drive basic parasite functions, such as meiosis, antigen diversification, and copy number variation, and allow the parasite to continually evolve in the contexts of host immune pressure and drug selection. Finally, we discuss the new technologies that leverage DSBR mechanisms to accelerate genetic investigations into this global infectious pathogen. PMID:25184562

Alisiaquinones and alisiaquinol, dual inhibitors of Plasmodium falciparum enzyme targets from a New Caledonian deep water sponge.

PubMed

Desoubzdanne, Denis; Marcourt, Laurence; Raux, Roselyne; Chevalley, Séverine; Dorin, Dominique; Doerig, Christian; Valentin, Alexis; Ausseil, Frédéric; Debitus, Cécile

2008-07-01

Four new meroterpenes, alisiaquinones A-C (1-3) and alisiaquinol (4), were isolated from a New Caledonian deep water sponge. Their structures and relative stereochemistry were elucidated by spectroscopic data analysis. They are related to xestoquinone, but showed unusual substitution on a tetrahydrofuran junction. They displayed micromolar range activity on two enzymatic targets of importance for the control of malaria, the plasmodial kinase Pfnek-1 and a protein farnesyl transferase, as well as on different chloroquine-sensitive and -resistant strains of Plasmodium falciparum. Alisiaquinone C displayed a submicromolar activity on P. falciparum and a competitive selectivity index on the different plasmodial strains.

A Lectin-Like Receptor is Involved in Invasion of Erythrocytes by Plasmodium falciparum

NASA Astrophysics Data System (ADS)

Jungery, M.; Pasvol, G.; Newbold, C. I.; Weatherall, D. J.

1983-02-01

Glycophorin both in solution and inserted into liposomes blocks invasion of erythrocytes by the malaria parasite Plasmodium falciparum. Furthermore, one sugar, N-acetyl-D-glucosamine (GlcNAc), completely blocks invasion of the erythrocyte by this parasite. GlcNAc coupled to bovine serum albumin to prevent the sugar entering infected erythrocytes was at least 100,000 times more effective than GlcNAc alone. Bovine serum albumin coupled to lactose or bovine serum albumin alone had no effect on invasion. These results suggest that the binding of P. falciparum to erythrocytes is lectin-like and is determined by carbohydrates on glycophorin.

Prevalence and risk factors of Plasmodium falciparum infections in pregnant women of Luanda, Angola.

PubMed

Valente, Bianor; Campos, Paulo A; do Rosário, Virgílio E; Varandas, Luis; Silveira, Henrique

2011-10-01

Pregnant women are at increased risk of malaria, but in Angola, epidemiologic data from this group is almost inexistent. We conducted a cross-sectional study to determine the prevalence and risk factors of Plasmodium falciparum infections in 567 pregnant Angolan women living in Luanda province. One in five women had P. falciparum at delivery, diagnosed by PCR assay. Age, residence and history of malaria during pregnancy were significantly associated with P. falciparum infection, but gravidity and use of anti-malarial drugs were not. Placental infections were significantly more common in women ≤18 years old and in primigravidae, but we could not correlate placental infections with poor pregnancy outcomes. These findings are relevant to malaria control policies in Luanda, Angola. © 2011 Blackwell Publishing Ltd.

Adenovirus Particles that Display the Plasmodium falciparum Circumsporozoite Protein NANP Repeat Induce Sporozoite-Neutralizing Antibodies in Mice

PubMed Central

Palma, Christopher; Overstreet, Michael G.; Guedon, Jean-Marc; Hoiczyk, Egbert; Ward, Cameron; Karen, Kasey A.; Zavala, Fidel; Ketner, Gary

2011-01-01

Adenovirus particles can be engineered to display exogenous peptides on their surfaces by modification of viral capsid proteins, and particles that display pathogen-derived peptides can induce protective immunity. We constructed viable recombinant adenoviruses that display B-cell epitopes from the Plasmodium falciparum circumsporozoite protein (PfCSP) in the major adenovirus capsid protein, hexon. Recombinants induced high-titer antibodies against CSP when injected intraperitoneally into mice. Serum obtained from immunized mice recognized both recombinant PfCSP protein and P. falciparum sporozoites, and neutralized P. falciparum sporozoites in vitro. Replicating adenovirus vaccines have provided economical protection against adenovirus disease for over three decades. The recombinants described here may provide a path to an affordable malaria vaccine in the developing world. PMID:21199707

Binding Isotope Effects for para-Aminobenzoic Acid with Dihydropteroate Synthase from Staphylococcus aureus and Plasmodium falciparum.

PubMed

Stratton, Christopher F; Namanja-Magliano, Hilda A; Cameron, Scott A; Schramm, Vern L

2015-10-16

Dihydropteroate synthase is a key enzyme in folate biosynthesis and is the target of the sulfonamide class of antimicrobials. Equilibrium binding isotope effects and density functional theory calculations indicate that the substrate binding sites for para-aminobenzoic acid on the dihydropteroate synthase enzymes from Staphylococcus aureus and Plasmodium falciparum present distinct chemical environments. Specifically, we show that para-aminobenzoic acid occupies a more sterically constrained vibrational environment when bound to dihydropteroate synthase from P. falciparum relative to that of S. aureus. Deletion of a nonhomologous, parasite-specific insert from the plasmodial dihydropteroate synthase abrogated the binding of para-aminobenzoic acid. The loop specific to P. falciparum is important for effective substrate binding and therefore plays a role in modulating the chemical environment at the substrate binding site.

Development of loop-mediated isothermal amplification with Plasmodium falciparum unique genes for molecular diagnosis of human malaria.

PubMed

Zhang, Yijing; Yao, Yi; Du, Weixing; Wu, Kai; Xu, Wenyue; Lin, Min; Tan, Huabing; Li, Jian

2017-07-01

In order to achieve better outcomes for treatment and in the prophylaxis of malaria, it is imperative to develop a sensitive, specific, and accurate assay for early diagnosis of Plasmodium falciparum infection, which is the major cause of malaria. In this study, we aimed to develop a loop-mediated isothermal amplification (LAMP) assay with P. falciparum unique genes for sensitive, specific, and accurate detection of P. falciparum infection. The unique genes of P. falciparum were randomly selected from PlasmoDB. The LAMP primers of the unique genes were designed using PrimerExplorer V4. LAMP assays with primers from unique genes of P. falciparum and conserved 18S rRNA gene were developed and their sensitivity was assessed. The specificity of the most sensitive LAMP assay was further examined using genomic DNA from Plasmodium vivax, Plasmodium yoelii and Toxoplasma gondii. Finally, the unique gene-based LAMP assay was validated using clinical samples of P. falciparum infection cases. A total of 31 sets of top-scored LAMP primers from nine unique genes were selected from the pools of designed primers. The LAMP assay with PF3D7_1253300-5 was the most sensitive with the detection limit 5 parasites/μl, and it displayed negative LAMP assay with the genomic DNA samples of P. vivax, P. yoelii, and T. gondii. The LAMP assay with PF3D7_0112300 (18S rRNA) was less sensitive with the detection limit 50 parasites/μl, and it displayed negative LAMP assay with the genomic DNA samples of P. yoelii and T. gondii, but displayed positive LAMP detection with P. vivax. The positive detection rate of the LAMP assay with PF3D7_1253300-5 was 90% (27/30), higher than that (80%, 24/30) of the positive rate of PF3D7_0112300 (18S rRNA) in examining clinical samples of P. falciparum infection cases. The LAMP assay with the primer set PF3D7_1253300-5 was more sensitive, specific, and accurate than those with PF3D7_0112300 (18S rRNA) in examining P. falciparum infection, and therefore it is a promising tool for diagnosis of P. falciparum infection.

The Association of High Prevalence of Trophozoites in Peripheral Blood with Lower Antibody Response to P. falciparum Infected Erythrocytes among Asymptomatic Children in Sudan.

PubMed

Mohamed, Sara N; Hassan, Dina A; El Hussein, Abdelrahim M; Osman, Ihssan M; Ibrahim, Muntasir E; Mohamed, Hiba S; Nour, Bakri Y; Abdulhadi, Nasreldin H

2016-01-01

Background. The most prominent variant surface antigens (VSAs) of Plasmodium falciparum are the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family, which serves as a parasite-sequestering ligand to endothelial cells. In this study we have examined the antibody reactivity of autologous plasma from symptomatic and asymptomatic malaria infected children against the infected erythrocytes' surface antigens using flow cytometry. Methods. Ethidium-bromide-labelled erythrocytic mature forms of P. falciparum parasites obtained from symptomatic and asymptomatic children were sequentially incubated with autologous plasma and fluorescein isothiocyanate-conjugated (FITC) antihuman IgG. Plasma antibody reactivity was detected by flow cytometry. Results. Asymptomatic children had more prevalence of trophozoites in peripheral blood (66%) compared to symptomatic children (16%), p = 0.002. The mean percentage of infected RBCs reacting with autologous sera was 89.78 among symptomatic children compared to 79.62 among asymptomatic children (p = 0.09). Moreover, the mean fluorescence intensity (MFI) in the asymptomatic was significantly higher compared to symptomatic children (p value = 0.040). Conclusion. Variant surface antigens on Plasmodium falciparum infected RBCs from symptomatic malaria children tend to be better recognized by IgG antibodies. This may suggest a role of some IgG antibodies in severity of malaria.

Plasmodium knowlesi: from severe zoonosis to animal model.

PubMed

Cox-Singh, Janet; Culleton, Richard

2015-06-01

Plasmodium knowlesi malaria is a newly described zoonosis in Southeast Asia. Similarly to Plasmodium falciparum, P. knowlesi can reach high parasitaemia in the human host and both species cause severe and fatal illness. Interpretation of host-parasite interactions in studies of P. knowlesi malaria adds a counterpoint to studies on P. falciparum. However, there is no model system for testing the resulting hypotheses on malaria pathophysiology or for developing new interventions. Plasmodium knowlesi is amenable to genetic manipulation in vitro and several nonhuman primate species are susceptible to experimental infection. Here, we make a case for drawing on P. knowlesi as both a human pathogen and an experimental model to lift the roadblock between malaria research and its translation into human health benefits. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Plasmodium falciparum copper-binding membrane protein with copper transport motifs

PubMed Central

2012-01-01

Background Copper is an essential catalytic co-factor for metabolically important cellular enzymes, such as cytochrome-c oxidase. Eukaryotic cells acquire copper through a copper transport protein and distribute intracellular copper using molecular chaperones. The copper chelator, neocuproine, inhibits Plasmodium falciparum ring-to-trophozoite transition in vitro, indicating a copper requirement for malaria parasite development. How the malaria parasite acquires or secretes copper still remains to be fully elucidated. Methods PlasmoDB was searched for sequences corresponding to candidate P. falciparum copper-requiring proteins. The amino terminal domain of a putative P. falciparum copper transport protein was cloned and expressed as a maltose binding fusion protein. The copper binding ability of this protein was examined. Copper transport protein-specific anti-peptide antibodies were generated in chickens and used to establish native protein localization in P. falciparum parasites by immunofluorescence microscopy. Results Six P. falciparum copper-requiring protein orthologs and a candidate P. falciparum copper transport protein (PF14_0369), containing characteristic copper transport protein features, were identified in PlasmoDB. The recombinant amino terminal domain of the transport protein bound reduced copper in vitro and within Escherichia coli cells during recombinant expression. Immunolocalization studies tracked the copper binding protein translocating from the erythrocyte plasma membrane in early ring stage to a parasite membrane as the parasites developed to schizonts. The protein appears to be a PEXEL-negative membrane protein. Conclusion Plasmodium falciparum parasites express a native protein with copper transporter characteristics that binds copper in vitro. Localization of the protein to the erythrocyte and parasite plasma membranes could provide a mechanism for the delivery of novel anti-malarial compounds. PMID:23190769

The adenosine deaminases of Plasmodium vivax and Plasmodium falciparum exhibit surprising differences in ligand specificity

PubMed Central

Ivanov, Andrei A.; Matsumura, Ichiro

2012-01-01

Plasmodium vivax and P. falciparum cause malaria, so proteins essential for their survival in vivo are potential anti-malarial drug targets. Adenosine deaminases (ADA) catalyze the irreversible conversion of adenosine into inosine, and play a critical role in the purine salvage pathways of Plasmodia and their mammalian hosts. Currently, the number of selective inhibitors of Plasmodium ADAs is limited. One potent and widely used inhibitor of the human ADA (hADA), erythro-9-(2-hydroxy-3-nonly)adenine (EHNA), is a very weak inhibitor (Ki = 120uM) of P. falciparum ADA (pfADA). EHNA-like compounds are thus excluded from consideration as potential inhibitors of Plasmodium ADA in general. However, EHNA activity in P. vivax ADA (pvADA) has not been reported. Here we applied computational molecular modeling to identify the mechanisms of the ligand recognition unique for P. vivax and P. falciparum ADA. Based on the computational studies, we performed molecular biology experiments to show that EHNA is at least 60-fold more potent against pvADA (Ki = 1.9uM) than against pfADA. The D172A pvADA mutant is bound even more tightly (Ki = 0.9uM). These results improve our understanding of the mechanisms of ADA ligand recognition and species-selectivity, and facilitate the rational design of novel EHNA-based ADA inhibitors as anti-malarial drugs. To demonstrate a practical application of our findings we have computationally predicted a novel potential inhibitor of pvADA selective versus the human ADA. PMID:22481078

Fatty acid synthesis and pyruvate metabolism pathways remain active in dihydroartemisinin-induced dormant ring stages of Plasmodium falciparum.

PubMed

Chen, Nanhua; LaCrue, Alexis N; Teuscher, Franka; Waters, Norman C; Gatton, Michelle L; Kyle, Dennis E; Cheng, Qin

2014-08-01

Artemisinin (ART)-based combination therapy (ACT) is used as the first-line treatment of uncomplicated falciparum malaria worldwide. However, despite high potency and rapid action, there is a high rate of recrudescence associated with ART monotherapy or ACT long before the recent emergence of ART resistance. ART-induced ring-stage dormancy and recovery have been implicated as possible causes of recrudescence; however, little is known about the characteristics of dormant parasites, including whether dormant parasites are metabolically active. We investigated the transcription of 12 genes encoding key enzymes in various metabolic pathways in P. falciparum during dihydroartemisinin (DHA)-induced dormancy and recovery. Transcription analysis showed an immediate downregulation for 10 genes following exposure to DHA but continued transcription of 2 genes encoding apicoplast and mitochondrial proteins. Transcription of several additional genes encoding apicoplast and mitochondrial proteins, particularly of genes encoding enzymes in pyruvate metabolism and fatty acid synthesis pathways, was also maintained. Additions of inhibitors for biotin acetyl-coenzyme A (CoA) carboxylase and enoyl-acyl carrier reductase of the fatty acid synthesis pathways delayed the recovery of dormant parasites by 6 and 4 days, respectively, following DHA treatment. Our results demonstrate that most metabolic pathways are downregulated in DHA-induced dormant parasites. In contrast, fatty acid and pyruvate metabolic pathways remain active. These findings highlight new targets to interrupt recovery of parasites from ART-induced dormancy and to reduce the rate of recrudescence following ART treatment. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

The detection of cryptic Plasmodium infection among villagers in Attapeu province, Lao PDR

PubMed Central

Khattignavong, Phonepadith; Soundala, Pheovaly; Lorphachan, Lavy; Matsumoto-Takahashi, Emilie; Strobel, Michel; Reinharz, Daniel; Phommasansack, Manisack; Hongvanthong, Bouasy; Brey, Paul T.

2017-01-01

Background Although the malaria burden in the Lao PDR has gradually decreased, the elimination of malaria by 2030 presents many challenges. Microscopy and malaria rapid diagnostic tests (RDTs) are used to diagnose malaria in the Lao PDR; however, some studies have reported the prevalence of sub-microscopic Plasmodium infections or asymptomatic Plasmodium carriers in endemic areas. Thus, highly sensitive detection methods are needed to understand the precise malaria situation in these areas. Methodology/Principal findings A cross-sectional malaria field survey was conducted in 3 highly endemic malaria districts (Xaysetha, Sanamxay, Phouvong) in Attapeu province, Lao PDR in 2015, to investigate the precise malaria endemicity in the area; 719 volunteers from these villages participated in the survey. Microscopy, RDTs and a real-time nested PCR were used to detect Plasmodium infections and their results were compared. A questionnaire survey of all participants was also conducted to estimate risk factors of Plasmodium infection. Numbers of infections detected by the three methods were microscopy: P. falciparum (n = 1), P. vivax (n = 2); RDTs: P. falciparum (n = 2), P. vivax (n = 3); PCR: Plasmodium (n = 47; P. falciparum [n = 4], P. vivax [n = 41], mixed infection [n = 2]; 6.5%, 47/719). Using PCR as a reference, the sensitivity and specificity of microscopy were 33.3% and 100.0%, respectively, for detecting P. falciparum infection, and 7.0% and 100.0%, for detecting P. vivax infection. Among the 47 participants with parasitemia, only one had a fever (≥37.5°C) and 31 (66.0%) were adult males. Risk factors of Plasmodium infection were males and soldiers, whereas a risk factor of asymptomatic Plasmodium infection was a history of ≥3 malaria episodes. Conclusions/Significance There were many asymptomatic Plasmodium carriers in the study areas of Attapeu province in 2015. Adult males, probably soldiers, were at high risk for malaria infection. P. vivax, the dominant species, accounted for 87.2% of the Plasmodium infections among the participants. To achieve malaria elimination in the Lao PDR, highly sensitive diagnostic tests, including PCR-based diagnostic methods should be used, and plans targeting high-risk populations and elimination of P. vivax should be designed and implemented. PMID:29261647

Agglutination Assays of the Plasmodium falciparum-Infected Erythrocyte.

PubMed

Tan, Joshua; Bull, Peter C

2015-01-01

The agglutination assay is used to determine the ability of antibodies to recognize parasite variant antigens on the surface of Plasmodium falciparum-infected erythrocytes. In this technique, infected erythrocytes are selectively labelled with a DNA-binding fluorescent dye and mixed with antibodies of interest to allow antibody-surface antigen binding. Recognition of surface antigens by the antibodies can result in the formation of agglutinates containing multiple parasite-infected erythrocytes. These can be viewed and quantified using a fluorescence microscope.

Origin and Dissemination of Chloroquine-Resistant Plasmodium falciparum with Mutant pfcrt Alleles in the Philippines

PubMed Central

Chen, Nanhua; Wilson, Danny W.; Pasay, Cielo; Bell, David; Martin, Laura B.; Kyle, Dennis; Cheng, Qin

2005-01-01

The pfcrt allelic type and adjacent microsatellite marker type were determined for 82 Plasmodium falciparum isolates from the Philippines. Mutant pfcrt allelic types P1a and P2a/P2b were dominant in different locations. Microsatellite analysis revealed that P2a/P2b evolved independently in the Philippines, while P1a shared common ancestry with Papua New Guinea chloroquine-resistant parasites. PMID:15855538

Complement and Antibody-Mediated Enhancement of Erythrocyte Invasion by Plasmodium Falciparum

DTIC Science & Technology

2016-04-01

Waki et al., 1995; Yoneto et al., 2001). However, the doses of antibody in those studies were much higher, usually given in milligram amounts and...erythrocyte receptor for Plasmodium falciparum PfRh4 invasion ligand. Proc. Natl. Acad. Sci. U. S. A. 107, 17327–17332. Waki , S., Uehara, S., Kanbe, K...infections. J. Immunol. 126, 1826–1828. Wold Health Organization, 2013. World Malaria Report 2013 (Geneva). Yoneto, T., Waki , S., Takai, T., Tagawa, Y

Comparison of molecular tests for the diagnosis of malaria in Honduras

PubMed Central

2012-01-01

Background Honduras is a tropical country with more than 70% of its population living at risk of being infected with either Plasmodium vivax or Plasmodium falciparum. Laboratory diagnosis is a very important factor for adequate treatment and management of malaria. In Honduras, malaria is diagnosed by both, microscopy and rapid diagnostic tests and to date, no molecular methods have been implemented for routine diagnosis. However, since mixed infections, and asymptomatic and low-parasitaemic cases are difficult to detect by light microscopy alone, identifying appropriate molecular tools for diagnostic applications in Honduras deserves further study. The present study investigated the utility of different molecular tests for the diagnosis of malaria in Honduras. Methods A total of 138 blood samples collected as part of a clinical trial to assess the efficacy of chloroquine were used: 69 microscopically confirmed P. falciparum positive samples obtained on the day of enrolment and 69 follow-up samples obtained 28 days after chloroquine treatment and shown to be malaria negative by microscopy. Sensitivity and specificity of microscopy was compared to an 18 s ribosomal RNA gene-based nested PCR, two single-PCR reactions designed to detect Plasmodium falciparum infections, one single-PCR to detect Plasmodium vivax infections, and one multiplex one-step PCR reaction to detect both parasite species. Results Of the 69 microscopically positive P. falciparum samples, 68 were confirmed to be P. falciparum-positive by two of the molecular tests used. The one sample not detected as P. falciparum by any of the molecular tests was shown to be P. vivax-positive by a reference molecular test indicating a misdiagnosis by microscopy. The reference molecular test detected five cases of P. vivax/P. falciparum mixed infections, which were not recognized by microscopy as mixed infections. Only two of these mixed infections were recognized by a multiplex test while a P. vivax-specific polymerase chain reaction (PCR) detected three of them. In addition, one of the day 28 samples, previously determined to be malaria negative by microscopy, was shown to be P. vivax-positive by three of the molecular tests specific for this parasite. Conclusions Molecular tests are valuable tools for the confirmation of Plasmodium species and in detecting mixed infections in malaria endemic regions. PMID:22513192

Comparison of molecular tests for the diagnosis of malaria in Honduras.

PubMed

Fontecha, Gustavo A; Mendoza, Meisy; Banegas, Engels; Poorak, Mitra; De Oliveira, Alexandre M; Mancero, Tamara; Udhayakumar, Venkatachalam; Lucchi, Naomi W; Mejia, Rosa E

2012-04-18

Honduras is a tropical country with more than 70% of its population living at risk of being infected with either Plasmodium vivax or Plasmodium falciparum. Laboratory diagnosis is a very important factor for adequate treatment and management of malaria. In Honduras, malaria is diagnosed by both, microscopy and rapid diagnostic tests and to date, no molecular methods have been implemented for routine diagnosis. However, since mixed infections, and asymptomatic and low-parasitaemic cases are difficult to detect by light microscopy alone, identifying appropriate molecular tools for diagnostic applications in Honduras deserves further study. The present study investigated the utility of different molecular tests for the diagnosis of malaria in Honduras. A total of 138 blood samples collected as part of a clinical trial to assess the efficacy of chloroquine were used: 69 microscopically confirmed P. falciparum positive samples obtained on the day of enrollment and 69 follow-up samples obtained 28 days after chloroquine treatment and shown to be malaria negative by microscopy. Sensitivity and specificity of microscopy was compared to an 18 s ribosomal RNA gene-based nested PCR, two single-PCR reactions designed to detect Plasmodium falciparum infections, one single-PCR to detect Plasmodium vivax infections, and one multiplex one-step PCR reaction to detect both parasite species. Of the 69 microscopically positive P. falciparum samples, 68 were confirmed to be P. falciparum-positive by two of the molecular tests used. The one sample not detected as P. falciparum by any of the molecular tests was shown to be P. vivax-positive by a reference molecular test indicating a misdiagnosis by microscopy. The reference molecular test detected five cases of P. vivax/P. falciparum mixed infections, which were not recognized by microscopy as mixed infections. Only two of these mixed infections were recognized by a multiplex test while a P. vivax-specific polymerase chain reaction (PCR) detected three of them. In addition, one of the day 28 samples, previously determined to be malaria negative by microscopy, was shown to be P. vivax-positive by three of the molecular tests specific for this parasite. Molecular tests are valuable tools for the confirmation of Plasmodium species and in detecting mixed infections in malaria endemic regions.

In vitro anti-Plasmodium falciparum properties of the full set of human secreted phospholipases A2.

PubMed

Guillaume, Carole; Payré, Christine; Jemel, Ikram; Jeammet, Louise; Bezzine, Sofiane; Naika, Gajendra S; Bollinger, James; Grellier, Philippe; Gelb, Michael H; Schrével, Joseph; Lambeau, Gérard; Deregnaucourt, Christiane

2015-06-01

We have previously shown that secreted phospholipases A2 (sPLA2s) from animal venoms inhibit the in vitro development of Plasmodium falciparum, the agent of malaria. In addition, the inflammatory-type human group IIA (hGIIA) sPLA2 circulates at high levels in the serum of malaria patients. However, the role of the different human sPLA2s in host defense against P. falciparum has not been investigated. We show here that 4 out of 10 human sPLA2s, namely, hGX, hGIIF, hGIII, and hGV, exhibit potent in vitro anti-Plasmodium properties with half-maximal inhibitory concentrations (IC50s) of 2.9 ± 2.4, 10.7 ± 2.1, 16.5 ± 9.7, and 94.2 ± 41.9 nM, respectively. Other human sPLA2s, including hGIIA, are inactive. The inhibition is dependent on sPLA2 catalytic activity and primarily due to hydrolysis of plasma lipoproteins from the parasite culture. Accordingly, purified lipoproteins that have been prehydrolyzed by hGX, hGIIF, hGIII, and hGV are more toxic to P. falciparum than native lipoproteins. However, the total enzymatic activities of human sPLA2s on purified lipoproteins or plasma did not reflect their inhibitory activities on P. falciparum. For instance, hGIIF is 9-fold more toxic than hGV but releases a lower quantity of nonesterified fatty acids (NEFAs). Lipidomic analyses of released NEFAs from lipoproteins demonstrate that sPLA2s with anti-Plasmodium properties are those that release polyunsaturated fatty acids (PUFAs), with hGIIF being the most selective enzyme. NEFAs purified from lipoproteins hydrolyzed by hGIIF were more potent at inhibiting P. falciparum than those from hGV, and PUFA-enriched liposomes hydrolyzed by sPLA2s were highly toxic, demonstrating the critical role of PUFAs. The selectivity of sPLA2s toward low- and high-density (LDL and HDL, respectively) lipoproteins and their ability to directly attack parasitized erythrocytes further explain their anti-Plasmodium activity. Together, our findings indicate that 4 human sPLA2s are active against P. falciparum in vitro and pave the way to future investigations on their in vivo contribution in malaria pathophysiology. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

In Vitro Anti-Plasmodium falciparum Properties of the Full Set of Human Secreted Phospholipases A2

PubMed Central

Guillaume, Carole; Payré, Christine; Jemel, Ikram; Jeammet, Louise; Bezzine, Sofiane; Naika, Gajendra S.; Bollinger, James; Grellier, Philippe; Gelb, Michael H.; Schrével, Joseph

2015-01-01

We have previously shown that secreted phospholipases A2 (sPLA2s) from animal venoms inhibit the in vitro development of Plasmodium falciparum, the agent of malaria. In addition, the inflammatory-type human group IIA (hGIIA) sPLA2 circulates at high levels in the serum of malaria patients. However, the role of the different human sPLA2s in host defense against P. falciparum has not been investigated. We show here that 4 out of 10 human sPLA2s, namely, hGX, hGIIF, hGIII, and hGV, exhibit potent in vitro anti-Plasmodium properties with half-maximal inhibitory concentrations (IC50s) of 2.9 ± 2.4, 10.7 ± 2.1, 16.5 ± 9.7, and 94.2 ± 41.9 nM, respectively. Other human sPLA2s, including hGIIA, are inactive. The inhibition is dependent on sPLA2 catalytic activity and primarily due to hydrolysis of plasma lipoproteins from the parasite culture. Accordingly, purified lipoproteins that have been prehydrolyzed by hGX, hGIIF, hGIII, and hGV are more toxic to P. falciparum than native lipoproteins. However, the total enzymatic activities of human sPLA2s on purified lipoproteins or plasma did not reflect their inhibitory activities on P. falciparum. For instance, hGIIF is 9-fold more toxic than hGV but releases a lower quantity of nonesterified fatty acids (NEFAs). Lipidomic analyses of released NEFAs from lipoproteins demonstrate that sPLA2s with anti-Plasmodium properties are those that release polyunsaturated fatty acids (PUFAs), with hGIIF being the most selective enzyme. NEFAs purified from lipoproteins hydrolyzed by hGIIF were more potent at inhibiting P. falciparum than those from hGV, and PUFA-enriched liposomes hydrolyzed by sPLA2s were highly toxic, demonstrating the critical role of PUFAs. The selectivity of sPLA2s toward low- and high-density (LDL and HDL, respectively) lipoproteins and their ability to directly attack parasitized erythrocytes further explain their anti-Plasmodium activity. Together, our findings indicate that 4 human sPLA2s are active against P. falciparum in vitro and pave the way to future investigations on their in vivo contribution in malaria pathophysiology. PMID:25824843

Genetic mutations in Plasmodium falciparum and Plasmodium vivax dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) in Vanuatu and Solomon Islands prior to the introduction of artemisinin combination therapy.

PubMed

Gresty, Karryn J; Gray, Karen-Ann; Bobogare, Albino; Wini, Lyndes; Taleo, George; Hii, Jeffrey; Cheng, Qin; Waters, Norman C

2014-10-14

Plasmodium falciparum and Plasmodium vivax are endemic in Vanuatu and the Solomon Islands. While both countries have introduced artemether-lumefantrine (AL) as first-line therapy for both P. falciparum and P. vivax since 2008, chloroquine and sulphadoxine-pyrimethamine (SP) were used as first-line therapy for many years prior to the introduction of AL. Limited data are available on the extent of SP resistance at the time of policy change. Blood spots were obtained from epidemiological surveys conducted on Tanna Island, Tafea Province, Vanuatu and Temotu Province, Solomon Islands in 2008. Additional samples from Malaita Province, Solomon Islands were collected as part of an AL therapeutic efficacy study conducted in 2008. Plasmodium vivax and P. falciparum dhfr and dhps genes were sequenced to detect nucleotide polymorphisms. All P. falciparum samples analysed (n=114) possessed a double mutant pfdhfr allele (C59R/S108N). Additionally, mutation A437G in pfhdps was detected in a small number of samples 2/13, 1/17 and 3/26 from Tanna Island, Vanuatu and Temotu and Malaita Provinces Solomon Islands respectively. Mutations were also common in pvdhfr from Tanna Island, Vanuatu, where 33/51 parasites carried the double amino acid substitution S58R/S117N, while in Temotu and Malaita Provinces, Solomon Islands 32/40 and 39/46 isolates carried the quadruple amino acid substitution F57L/S58R/T61M/S117T in DHFR respectively. No mutations in pvdhps (n=108) were detected in these three island groups. Prior to the introduction of AL, there was a moderate level of SP resistance in the P. falciparum population that may cause SP treatment failure in young children. Of the P. vivax isolates, a majority of Solomon Islands isolates carried quadruple mutant pvdhfr alleles while a majority of Vanuatu isolates carried double mutant pvdhfr alleles. This suggests a higher level of SP resistance in the P. vivax population in Solomon Islands compared to the sympatric P. falciparum population and there is a higher level of SP resistance in P. vivax parasites from Solomon Islands than Vanuatu. This study demonstrates that the change of treatment policy in these countries from SP to ACT was timely. The information also provides a baseline for future monitoring.

High proportion of knowlesi malaria in recent malaria cases in Malaysia

PubMed Central

2014-01-01

Background Plasmodium knowlesi is a simian parasite that has been recognized as the fifth species causing human malaria. Naturally-acquired P. knowlesi infection is widespread among human populations in Southeast Asia. The aim of this epidemiological study was to determine the incidence and distribution of malaria parasites, with a particular focus on human P. knowlesi infection in Malaysia. Methods A total of 457 microscopically confirmed, malaria-positive blood samples were collected from 22 state and main district hospitals in Malaysia between September 2012 and December 2013. Nested PCR assay targeting the 18S rRNA gene was used to determine the infecting Plasmodium species. Results A total of 453 samples were positive for Plasmodium species by using nested PCR assay. Plasmodium knowlesi was identified in 256 (56.5%) samples, followed by 133 (29.4%) cases of Plasmodium vivax, 49 (10.8%) cases of Plasmodium falciparum, two (0.4%) cases of Plasmodium ovale and one (0.2%) case of Plasmodium malariae. Twelve mixed infections were detected, including P. knowlesi/P. vivax (n = 10), P. knowlesi/P. falciparum (n = 1), and P. falciparum/P. vivax (n = 1). Notably, P. knowlesi (Included mixed infections involving P. knowlesi (P. knowlesi/P. vivax and P. knowlesi /P. falciparum)) showed the highest proportion in Sabah (84/115 cases, prevalence of 73.0%), Sarawak (83/120, 69.2%), Kelantan (42/56, 75.0%), Pahang (24/25, 96.0%), Johor (7/9, 77.8%), and Terengganu (4/5, 80.0%,). In contrast, the rates of P. knowlesi infection in Selangor and Negeri Sembilan were found to be 16.2% (18/111 cases) and 50.0% (5/10 cases), respectively. Sample of P. knowlesi was not obtained from Kuala Lumpur, Melaka, Perak, Pulau Pinang, and Perlis during the study period, while a microscopically-positive sample from Kedah was negative by PCR. Conclusion In addition to Sabah and Sarawak, which have been known for high prevalence of P. knowlesi infection, the findings from this study highlight the widespread distribution of P. knowlesi in many Peninsular Malaysia states. PMID:24886266

Computational identification of signalling pathways in Plasmodium falciparum.

PubMed

Oyelade, Jelili; Ewejobi, Itunu; Brors, Benedikt; Eils, Roland; Adebiyi, Ezekiel

2011-06-01

Malaria is one of the world's most common and serious diseases causing death of about 3 million people each year. Its most severe occurrence is caused by the protozoan Plasmodium falciparum. Reports have shown that the resistance of the parasite to existing drugs is increasing. Therefore, there is a huge and urgent need to discover and validate new drug or vaccine targets to enable the development of new treatments for malaria. The ability to discover these drug or vaccine targets can only be enhanced from our deep understanding of the detailed biology of the parasite, for example how cells function and how proteins organize into modules such as metabolic, regulatory and signal transduction pathways. It has been noted that the knowledge of signalling transduction pathways in Plasmodium is fundamental to aid the design of new strategies against malaria. This work uses a linear-time algorithm for finding paths in a network under modified biologically motivated constraints. We predicted several important signalling transduction pathways in Plasmodium falciparum. We have predicted a viable signalling pathway characterized in terms of the genes responsible that may be the PfPKB pathway recently elucidated in Plasmodium falciparum. We obtained from the FIKK family, a signal transduction pathway that ends up on a chloroquine resistance marker protein, which indicates that interference with FIKK proteins might reverse Plasmodium falciparum from resistant to sensitive phenotype. We also proposed a hypothesis that showed the FIKK proteins in this pathway as enabling the resistance parasite to have a mechanism for releasing chloroquine (via an efflux process). Furthermore, we also predicted a signalling pathway that may have been responsible for signalling the start of the invasion process of Red Blood Cell (RBC) by the merozoites. It has been noted that the understanding of this pathway will give insight into the parasite virulence and will facilitate rational vaccine design against merozoites invasion. And we have a host of other predicted pathways, some of which have been used in this work to predict the functionality of some proteins. Copyright © 2010 Elsevier B.V. All rights reserved.

A bioinformatic survey of RNA-binding proteins in Plasmodium.

PubMed

Reddy, B P Niranjan; Shrestha, Sony; Hart, Kevin J; Liang, Xiaoying; Kemirembe, Karen; Cui, Liwang; Lindner, Scott E

2015-11-02

The malaria parasites in the genus Plasmodium have a very complicated life cycle involving an invertebrate vector and a vertebrate host. RNA-binding proteins (RBPs) are critical factors involved in every aspect of the development of these parasites. However, very few RBPs have been functionally characterized to date in the human parasite Plasmodium falciparum. Using different bioinformatic methods and tools we searched P. falciparum genome to list and annotate RBPs. A representative 3D models for each of the RBD domain identified in P. falciparum was created using I-TESSAR and SWISS-MODEL. Microarray and RNAseq data analysis pertaining PfRBPs was performed using MeV software. Finally, Cytoscape was used to create protein-protein interaction network for CITH-Dozi and Caf1-CCR4-Not complexes. We report the identification of 189 putative RBP genes belonging to 13 different families in Plasmodium, which comprise 3.5% of all annotated genes. Almost 90% (169/189) of these genes belong to six prominent RBP classes, namely RNA recognition motifs, DEAD/H-box RNA helicases, K homology, Zinc finger, Puf and Alba gene families. Interestingly, almost all of the identified RNA-binding helicases and KH genes have cognate homologs in model species, suggesting their evolutionary conservation. Exploration of the existing P. falciparum blood-stage transcriptomes revealed that most RBPs have peak mRNA expression levels early during the intraerythrocytic development cycle, which taper off in later stages. Nearly 27% of RBPs have elevated expression in gametocytes, while 47 and 24% have elevated mRNA expression in ookinete and asexual stages. Comparative interactome analyses using human and Plasmodium protein-protein interaction datasets suggest extensive conservation of the PfCITH/PfDOZI and PfCaf1-CCR4-NOT complexes. The Plasmodium parasites possess a large number of putative RBPs belonging to most of RBP families identified so far, suggesting the presence of extensive post-transcriptional regulation in these parasites. Taken together, in silico identification of these putative RBPs provides a foundation for future functional studies aimed at defining a unique network of post-transcriptional regulation in P. falciparum.

Routine parallel diagnosis of malaria using microscopy and the malaria rapid diagnostic test SD 05FK60: the experience of Médecins Sans Frontières in Myanmar.

PubMed

Kosack, Cara S; Naing, Wint Thu; Piriou, Erwan; Shanks, Leslie

2013-05-21

Malaria rapid diagnostic tests (RDTs) are commonly used in Médecins Sans Frontières (MSF) programmes to detect acute malaria infection. Programmes in regions with both Plasmodium falciparum and non-falciparum malaria (i.e. Plasmodium ovale, Plasmodium malariae and Plasmodium vivax) use a three-band P. falciparum/Pan test such as the SD Bioline Malaria Ag P.f/Pan 05FK60 (Standard Diagnostics, Kyonggi, Republic of Korea), hereafter referred to as SD 05FK60, as used by the MSF-Holland clinics in Rakhine state, Myanmar. In spite of published reports of generally good test performance, medical and paramedical staff on the ground often doubt the diagnostic accuracy of these RDTs. Parallel testing with malaria microscopy and RDT was conducted at two clinics in Rakhine state, Myanmar, for a period of 14 months as a programmatic response due to doubts and concerns of medical and paramedical staff into malaria RDTs. A total of 2,585 blood samples from non-pregnant suspected malaria patients were examined by the SD 05FK60 RDT and microscopy at two clinics in Myanmar from October 2010 to December 2011. The reference standard microscopy diagnosed 531 P. falciparum and 587 P. vivax or P. malariae mono-infections. The overall sensitivity for P. falciparum detection by the SD 05FK60 was 90.2% (95% CI: 87.4-92.6) and for P. vivax/P. malariae 79.4% (95% CI: 75.9-82.6). The overall specificity for P. falciparum detection by the SD 05FK60 was 98.5% (95% CI: 97.7-99.1) and for P. vivax/P. malariae 98.7% (95% CI: 97.9-99.2). The sensitivity for P. falciparum was >91% for parasitaemia levels of >100-1,000 parasites/μl and increased for P. vivax/P. malariae with the parasitaemia level but was overall lower than for P. falciparum 25/408 and 13/420 cases, respectively, of P. falciparum and non-falciparum malaria were missed by the RDT. In field conditions in Myanmar, the SD 05FK60 malaria RDT performed consistent with other reports. The test detected malaria caused by P. vivax/P. malariae to a lesser extent than P. falciparum infection. Sensitivity improved with increasing parasitaemia level, however even at higher levels some infections were missed. The SD 05FK60 is adequate for use in settings where high quality microscopy is not available.

Multiple independent introductions of Plasmodium falciparum in South America

PubMed Central

Yalcindag, Erhan; Elguero, Eric; Arnathau, Céline; Durand, Patrick; Akiana, Jean; Anderson, Timothy J.; Aubouy, Agnes; Balloux, François; Besnard, Patrick; Bogreau, Hervé; Carnevale, Pierre; D'Alessandro, Umberto; Fontenille, Didier; Gamboa, Dionicia; Jombart, Thibaut; Le Mire, Jacques; Leroy, Eric; Maestre, Amanda; Mayxay, Mayfong; Ménard, Didier; Musset, Lise; Newton, Paul N.; Nkoghé, Dieudonné; Noya, Oscar; Ollomo, Benjamin; Rogier, Christophe; Veron, Vincent; Wide, Albina; Zakeri, Sedigheh; Carme, Bernard; Legrand, Eric; Chevillon, Christine; Ayala, Francisco J.; Renaud, François; Prugnolle, Franck

2012-01-01

The origin of Plasmodium falciparum in South America is controversial. Some studies suggest a recent introduction during the European colonizations and the transatlantic slave trade. Other evidence—archeological and genetic—suggests a much older origin. We collected and analyzed P. falciparum isolates from different regions of the world, encompassing the distribution range of the parasite, including populations from sub-Saharan Africa, the Middle East, Southeast Asia, and South America. Analyses of microsatellite and SNP polymorphisms show that the populations of P. falciparum in South America are subdivided in two main genetic clusters (northern and southern). Phylogenetic analyses, as well as Approximate Bayesian Computation methods suggest independent introductions of the two clusters from African sources. Our estimates of divergence time between the South American populations and their likely sources favor a likely introduction from Africa during the transatlantic slave trade. PMID:22203975

Plasmodium evasion of mosquito immunity and global malaria transmission: The lock-and-key theory.

PubMed

Molina-Cruz, Alvaro; Canepa, Gaspar E; Kamath, Nitin; Pavlovic, Noelle V; Mu, Jianbing; Ramphul, Urvashi N; Ramirez, Jose Luis; Barillas-Mury, Carolina

2015-12-08

Plasmodium falciparum malaria originated in Africa and became global as humans migrated to other continents. During this journey, parasites encountered new mosquito species, some of them evolutionarily distant from African vectors. We have previously shown that the Pfs47 protein allows the parasite to evade the mosquito immune system of Anopheles gambiae mosquitoes. Here, we investigated the role of Pfs47-mediated immune evasion in the adaptation of P. falciparum to evolutionarily distant mosquito species. We found that P. falciparum isolates from Africa, Asia, or the Americas have low compatibility to malaria vectors from a different continent, an effect that is mediated by the mosquito immune system. We identified 42 different haplotypes of Pfs47 that have a strong geographic population structure and much lower haplotype diversity outside Africa. Replacement of the Pfs47 haplotypes in a P. falciparum isolate is sufficient to make it compatible to a different mosquito species. Those parasites that express a Pfs47 haplotype compatible with a given vector evade antiplasmodial immunity and survive. We propose that Pfs47-mediated immune evasion has been critical for the globalization of P. falciparum malaria as parasites adapted to new vector species. Our findings predict that this ongoing selective force by the mosquito immune system could influence the dispersal of Plasmodium genetic traits and point to Pfs47 as a potential target to block malaria transmission. A new model, the "lock-and-key theory" of P. falciparum globalization, is proposed, and its implications are discussed.

Multigenomic Delineation of Plasmodium Species of the Laverania Subgenus Infecting Wild-Living Chimpanzees and Gorillas.

PubMed

Liu, Weimin; Sundararaman, Sesh A; Loy, Dorothy E; Learn, Gerald H; Li, Yingying; Plenderleith, Lindsey J; Ndjango, Jean-Bosco N; Speede, Sheri; Atencia, Rebeca; Cox, Debby; Shaw, George M; Ayouba, Ahidjo; Peeters, Martine; Rayner, Julian C; Hahn, Beatrice H; Sharp, Paul M

2016-07-02

Plasmodium falciparum, the major cause of malaria morbidity and mortality worldwide, is only distantly related to other human malaria parasites and has thus been placed in a separate subgenus, termed Laverania Parasites morphologically similar to P. falciparum have been identified in African apes, but only one other Laverania species, Plasmodium reichenowi from chimpanzees, has been formally described. Although recent studies have pointed to the existence of additional Laverania species, their precise number and host associations remain uncertain, primarily because of limited sampling and a paucity of parasite sequences other than from mitochondrial DNA. To address this, we used limiting dilution polymerase chain reaction to amplify additional parasite sequences from a large number of chimpanzee and gorilla blood and fecal samples collected at two sanctuaries and 30 field sites across equatorial Africa. Phylogenetic analyses of more than 2,000 new sequences derived from the mitochondrial, nuclear, and apicoplast genomes revealed six divergent and well-supported clades within the Laverania parasite group. Although two of these clades exhibited deep subdivisions in phylogenies estimated from organelle gene sequences, these sublineages were geographically defined and not present in trees from four unlinked nuclear loci. This greatly expanded sequence data set thus confirms six, and not seven or more, ape Laverania species, of which P. reichenowi, Plasmodium gaboni, and Plasmodium billcollinsi only infect chimpanzees, whereas Plasmodium praefalciparum, Plasmodium adleri, and Pladmodium blacklocki only infect gorillas. The new sequence data also confirm the P. praefalciparum origin of human P. falciparum. © The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Investigating the activity of quinine analogues versus chloroquine resistant Plasmodium falciparum.

PubMed

Dinio, Theresa; Gorka, Alexander P; McGinniss, Andrew; Roepe, Paul D; Morgan, Jeremy B

2012-05-15

Plasmodium falciparum, the deadliest malarial parasite species, has developed resistance against nearly all man-made antimalarial drugs within the past century. However, quinine (QN), the first antimalarial drug, remains efficacious worldwide. Some chloroquine resistant (CQR) P. falciparum strains or isolates show mild cross resistance to QN, but many do not. Further optimization of QN may provide a well-tolerated therapy with improved activity versus CQR malaria. Thus, using the Heck reaction, we have pursued a structure-activity relationship study, including vinyl group modifications of QN. Certain derivatives show good antiplasmodial activity in QN-resistant and QN-sensitive strains, with lower IC(50) values relative to QN. Copyright © 2012 Elsevier Ltd. All rights reserved.

Structure of the catalytic domain of Plasmodium falciparum ARF GTPase-activating protein (ARFGAP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, William J.; Senkovich, Olga; Chattopadhyay, Debasish

2012-03-26

The crystal structure of the catalytic domain of the ADP ribosylation factor GTPase-activating protein (ARFGAP) from Plasmodium falciparum has been determined and refined to 2.4 {angstrom} resolution. Multiwavelength anomalous diffraction (MAD) data were collected utilizing the Zn{sup 2+} ion bound at the zinc-finger domain and were used to solve the structure. The overall structure of the domain is similar to those of mammalian ARFGAPs. However, several amino-acid residues in the area where GAP interacts with ARF1 differ in P. falciparum ARFGAP. Moreover, a number of residues that form the dimer interface in the crystal structure are unique in P. falciparummore » ARFGAP.« less

Infection of Aotus azarae boliviensis monkeys with different strains of Plasmodium falciparum.

PubMed

Collins, W E; Skinner, J C; Broderson, J R; Huong, A Y; Mehaffey, P C; Stanfill, P S; Sutton, B B

1986-08-01

Eleven strains of Plasmodium falciparum from Asia, Africa, and Central America were inoculated into a total of 58 splenectomized Aotus azarae boliviensis monkeys. Eight of the strains produced high-level parasitemias, whereas 3 (2 from Honduras and 1 from Zaire) produced only low-level parasitemias. Mosquito infections were only obtained during the first 2 linear passages of the Santa Lucia strain from El Salvador. The results indicate that this species of Aotus monkey is highly susceptible to infection with strains of P. falciparum from different geographic areas, and therefore may be useful for a number of chemotherapeutic or immunologic studies. Its usefulness for mosquito infection studies is very limited.

The shape of the iceberg: quantification of submicroscopic Plasmodium falciparum and Plasmodium vivax parasitaemia and gametocytaemia in five low endemic settings in Ethiopia.

PubMed

Tadesse, Fitsum G; van den Hoogen, Lotus; Lanke, Kjerstin; Schildkraut, Jodie; Tetteh, Kevin; Aseffa, Abraham; Mamo, Hassen; Sauerwein, Robert; Felger, Ingrid; Drakeley, Chris; Gadissa, Endalamaw; Bousema, Teun

2017-03-03

The widespread presence of low-density asymptomatic infections with concurrent gametocytes may be a stumbling block for malaria elimination. This study investigated the asymptomatic reservoir of Plasmodium falciparum and Plasmodium vivax infections in schoolchildren from five settings in northwest Ethiopia. Two cross-sectional surveys were conducted in June and November 2015, enrolling 551 students from five schools and 294 students from three schools, respectively. Finger prick whole blood and plasma samples were collected. The prevalence and density of P. falciparum and P. vivax parasitaemia and gametocytaemia were determined by 18S rRNA quantitative PCR (qPCR) and pfs25 and pvs25 reverse transcriptase qPCR. Antibodies against blood stage antigens apical membrane antigen-1 (AMA-1) and merozoite surface protein-1 (MSP-1 19 ) were measured for both species. Whilst only 6 infections were detected by microscopy in 881 slides (0.7%), 107 of 845 blood samples (12.7%) were parasite positive by (DNA-based) qPCR. qPCR parasite prevalence between sites and surveys ranged from 3.8 to 19.0% for P. falciparum and 0.0 to 9.0% for P. vivax. The median density of P. falciparum infections (n = 85) was 24.4 parasites/µL (IQR 18.0-34.0) and the median density of P. vivax infections (n = 28) was 16.4 parasites/µL (IQR 8.8-55.1). Gametocyte densities by (mRNA-based) qRT-PCR were strongly associated with total parasite densities for both P. falciparum (correlation coefficient = 0.83, p = 0.010) and P. vivax (correlation coefficient = 0.58, p = 0.010). Antibody titers against P. falciparum AMA-1 and MSP-1 19 were higher in individuals who were P. falciparum parasite positive in both surveys (p < 0.001 for both comparisons). This study adds to the available evidence on the wide-scale presence of submicroscopic parasitaemia by quantifying submicroscopic parasite densities and concurrent gametocyte densities. There was considerable heterogeneity in the occurrence of P. falciparum and P. vivax infections and serological markers of parasite exposure between the examined low endemic settings in Ethiopia.

Specific Receptor Usage in Plasmodium falciparum Cytoadherence Is Associated with Disease Outcome

PubMed Central

Ochola, Lucy B.; Siddondo, Bethsheba R.; Ocholla, Harold; Nkya, Siana; Kimani, Eva N.; Williams, Thomas N.; Makale, Johnstone O.; Liljander, Anne; Urban, Britta C.; Bull, Pete C.; Szestak, Tadge; Marsh, Kevin; Craig, Alister G.

2011-01-01

Our understanding of the basis of severe disease in malaria is incomplete. It is clear that pathology is in part related to the pro-inflammatory nature of the host response but a number of other factors are also thought to be involved, including the interaction between infected erythrocytes and endothelium. This is a complex system involving several host receptors and a major parasite-derived variant antigen (PfEMP1) expressed on the surface of the infected erythrocyte membrane. Previous studies have suggested a role for ICAM-1 in the pathology of cerebral malaria, although these have been inconclusive. In this study we have examined the cytoadherence patterns of 101 patient isolates from varying clinical syndromes to CD36 and ICAM-1, and have used variant ICAM-1 proteins to further characterise this adhesive phenotype. Our results show that increased binding to CD36 is associated with uncomplicated malaria while ICAM-1 adhesion is raised in parasites from cerebral malaria cases. PMID:21390226

Partial purification and characterization of DNA topoisomerase II from Plasmodium falciparum.

PubMed

Chavalitshewinkoon, P; Leelaphiwat, S; Wilairat, P

1994-03-01

DNA topoisomerase II from Plasmodium falciparum was partially purified by FPLC using three columns: Econo-Pac Q, heparin-agarose and Mono Q. The enzyme showed ATP- and Mg2 +/- dependent activities in a decatenation assay, with optimum concentrations of 0.5 and 10 mM, respectively. Furthermore, highest activity was detected in the presence of 100 mM KCI. Enzyme decatenation activity was not inhibited by the DNA topoisomerase I inhibitor, camptothecin, but was sensitive to both prokaryotic and eukaryotic DNA topoisomerase II inhibitors.

Treatment for Uncomplicated Plasmodium falciparum Malaria in French Soldiers Deployed in Sub-Saharan Africa: Gaps Between Policy and Field Practice.

PubMed

Perisse, Anne; Velut, Guillaume; Javelle, Emilie; Loarer, Gwion; Michel, Remy; Simon, F

2018-02-07

Malaria prevention and treatment are big challenges for the French forces deployed in sub-Saharan Africa. Since December 2013, 1,800 French soldiers have been deployed at any one time in the Central African Republic in the framework of "Operation Sangaris" and European Union Force (EUFOR). Over the 2014-2015 period, about 500 cases of malaria were notified in these troops during the operation or after their return (annual incidence: 13.4 p.100 person-year). The recommendation to use dihydroartemisinin-piperaquine (DHA-PQ) as the first-line treatment for French soldiers suffering from uncomplicated Plasmodium falciparum malaria in endemic areas is not always followed in practice in the field by French military general practitioners (GPs). We conduced a retrospective Knowledge-Attitude-Practice study by self-administered questionnaire, to all military French doctors who were in mission in Central African Republic from January 2014 to July 2015 to try to understand what were the reasons for the GP not to prescribe DHA-PQ on the field. Thirty-six GPs (53%) answered to the questionnaire. Eighty-three percent of them knew about the recommendation to use DHA-PQ for un uncomplicated Pf malaria. Fifty-eight percent had a favorable attitude toward DHA-PQ. The factors associated with the prescription of another drug (Atovaquone-proguanil) were: the habit (odds ratio [OR] 0.1, confidence interval (CI) 0-0.6], the fact that Atovaquone-proguanil is more practical to use [OR 0.01, CI 0-0.1]. In practice, only 37.5% prescribed DHA-PQ the most of the time during their mission. Factors associated with a non-favorable attitude toward DHA-PQ were: the necessity to calculate a QTc interval during the treatment [OR 0.2, confidence interval 0-0.9], and the fact that DHA-PQ must be taken on an empty stomach [OR 0.3, CI 0.1-0.8]. GP who received a formation before their mission about malaria and treatment had a favorable attitude toward DHA-PQ. There is very satisfactory knowledge by the military GPs stationed in the Central African Republic on both the recommendations and prescription of antimalarial drugs. The present study highlights some difficulties in implementing the recommendations in an operational context, notably factors limiting the prescription of DHA-PQ during military deployment (need for ECG monitoring, empty stomach, and lack of habit). Proposals can be made to improve the efficacy, tolerance, and practicability of malaria treatment in the field. The main focus should be a more flexible application of the French DHA-PQ risk management plan in the field, specific training and communication about DHA-PQ use, the generalization of ECG printing equipment in the field, and the switch from DHA-PQ to an alternative artemisinin-based combination therapy during deployments in malaria-endemic areas. © Association of Military Surgeons of the United States 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Proteomic Identification and Analysis of Arginine-Methylated Proteins of Plasmodium falciparum at Asexual Blood Stages.

PubMed

Zeeshan, Mohammad; Kaur, Inderjeet; Joy, Joseph; Saini, Ekta; Paul, Gourab; Kaushik, Abhinav; Dabral, Surbhi; Mohmmed, Asif; Gupta, Dinesh; Malhotra, Pawan

2017-02-03

Plasmodium falciparum undergoes a tightly regulated developmental process in human erythrocytes, and recent studies suggest an important regulatory role of post-translational modifications (PTMs). As compared with Plasmodium phosphoproteome, little is known about other PTMs in the parasite. In the present study, we performed a global analysis of asexual blood stages of Plasmodium falciparum to identify arginine-methylated proteins. Using two different methyl arginine-specific antibodies, we immunoprecipitated the arginine-methylated proteins from the stage-specific parasite lysates and identified 843 putative arginine-methylated proteins by LC-MS/MS. Motif analysis of the protein sequences unveiled that the methylation sites are associated with the previously known methylation motifs such as GRx/RGx, RxG, GxxR, or WxxxR. We identified Plasmodium homologues of known arginine-methylated proteins in trypanosomes, yeast, and human. Hydrophilic interaction liquid chromatography (HILIC) was performed on the immunoprecipitates from the trophozoite stage to enrich arginine-methylated peptides. Mass spectrometry analysis of immunoprecipitated and HILIC fractions identified 55 arginine-methylated peptides having 62 methylated arginine sites. Functional classification revealed that the arginine-methylated proteins are involved in RNA metabolism, protein synthesis, intracellular protein trafficking, proteolysis, protein folding, chromatin organization, hemoglobin metabolic process, and several other functions. Summarily, the findings suggest that protein methylation of arginine residues is a widespread phenomenon in Plasmodium, and the PTM may play an important regulatory role in a diverse set of biological pathways, including host-pathogen interactions.

Plasmodium falciparum-Derived Uric Acid Precipitates Induce Maturation of Dendritic Cells

PubMed Central

van de Hoef, Diana L.; Coppens, Isabelle; Holowka, Thomas; Ben Mamoun, Choukri; Branch, OraLee; Rodriguez, Ana

2013-01-01

Malaria is characterized by cyclical fevers and high levels of inflammation, and while an early inflammatory response contributes to parasite clearance, excessive and persistent inflammation can lead to severe forms of the disease. Here, we show that Plasmodium falciparum-infected erythrocytes contain uric acid precipitates in the cytoplasm of the parasitophorous vacuole, which are released when erythrocytes rupture. Uric acid precipitates are highly inflammatory molecules that are considered a danger signal for innate immunity and are the causative agent in gout. We determined that P. falciparum-derived uric acid precipitates induce maturation of human dendritic cells, increasing the expression of cell surface co-stimulatory molecules such as CD80 and CD86, while decreasing human leukocyte antigen-DR expression. In accordance with this, uric acid accounts for a significant proportion of the total stimulatory activity induced by parasite-infected erythrocytes. Moreover, the identification of uric acid precipitates in P. falciparum- and P. vivax-infected erythrocytes obtained directly from malaria patients underscores the in vivo and clinical relevance of our findings. Altogether, our data implicate uric acid precipitates as a potentially important contributor to the innate immune response to Plasmodium infection and may provide a novel target for adjunct therapies. PMID:23405174

Plasmodium falciparum centromeres display a unique epigenetic makeup and cluster prior to and during schizogony.

PubMed

Hoeijmakers, Wieteke A M; Flueck, Christian; Françoijs, Kees-Jan; Smits, Arne H; Wetzel, Johanna; Volz, Jennifer C; Cowman, Alan F; Voss, Till; Stunnenberg, Hendrik G; Bártfai, Richárd

2012-09-01

Centromeres are essential for the faithful transmission of chromosomes to the next generation, therefore being essential in all eukaryotic organisms. The centromeres of Plasmodium falciparum, the causative agent of the most severe form of malaria, have been broadly mapped on most chromosomes, but their epigenetic composition remained undefined. Here, we reveal that the centromeric histone variant PfCENH3 occupies a 4-4.5 kb region on each P. falciparum chromosome, which is devoid of pericentric heterochromatin but harbours another histone variant, PfH2A.Z. These CENH3 covered regions pinpoint the exact position of the centromere on all chromosomes and revealed that all centromeric regions have similar size and sequence composition. Immunofluorescence assay of PfCENH3 strongly suggests that P. falciparum centromeres cluster to a single nuclear location prior to and during mitosis and cytokinesis but dissociate soon after invasion. In summary, we reveal a dynamic association of Plasmodium centromeres, which bear a unique epigenetic signature and conform to a strict structure. These findings suggest that DNA-associated and epigenetic elements play an important role in centromere establishment in this important human pathogen. © 2012 Blackwell Publishing Ltd.

Genomes of all known members of a Plasmodium subgenus reveal paths to virulent human malaria.

PubMed

Otto, Thomas D; Gilabert, Aude; Crellen, Thomas; Böhme, Ulrike; Arnathau, Céline; Sanders, Mandy; Oyola, Samuel O; Okouga, Alain Prince; Boundenga, Larson; Willaume, Eric; Ngoubangoye, Barthélémy; Moukodoum, Nancy Diamella; Paupy, Christophe; Durand, Patrick; Rougeron, Virginie; Ollomo, Benjamin; Renaud, François; Newbold, Chris; Berriman, Matthew; Prugnolle, Franck

2018-06-01

Plasmodium falciparum, the most virulent agent of human malaria, shares a recent common ancestor with the gorilla parasite Plasmodium praefalciparum. Little is known about the other gorilla- and chimpanzee-infecting species in the same (Laverania) subgenus as P. falciparum, but none of them are capable of establishing repeated infection and transmission in humans. To elucidate underlying mechanisms and the evolutionary history of this subgenus, we have generated multiple genomes from all known Laverania species. The completeness of our dataset allows us to conclude that interspecific gene transfers, as well as convergent evolution, were important in the evolution of these species. Striking copy number and structural variations were observed within gene families and one, stevor, shows a host-specific sequence pattern. The complete genome sequence of the closest ancestor of P. falciparum enables us to estimate the timing of the beginning of speciation to be 40,000-60,000 years ago followed by a population bottleneck around 4,000-6,000 years ago. Our data allow us also to search in detail for the features of P. falciparum that made it the only member of the Laverania able to infect and spread in humans.

Efficacy of monthly tafenoquine for prophylaxis of Plasmodium vivax and multidrug-resistant P. falciparum malaria.

PubMed

Walsh, Douglas S; Eamsila, Chirapa; Sasiprapha, Theerayuth; Sangkharomya, Suebpong; Khaewsathien, Pradith; Supakalin, Panpaka; Tang, Douglas B; Jarasrumgsichol, Phongsak; Cherdchu, Chainarong; Edstein, Michael D; Rieckmann, Karl H; Brewer, Thomas G

2004-10-15

We assessed monthly doses of tafenoquine for preventing Plasmodium vivax and multidrug-resistant P. falciparum malaria. In a randomized, double-blind, placebo-controlled study, 205 Thai soldiers received either a loading dose of tafenoquine 400 mg (base) daily for 3 days, followed by single monthly 400-mg doses (n = 104), or placebo (n = 101), for up to 5 consecutive months. In volunteers completing follow-up (96 tafenoquine and 91 placebo recipients), there were 22 P. vivax, 8 P. falciparum, and 1 mixed infection. All infections except 1 P. vivax occurred in placebo recipients, giving tafenoquine a protective efficacy of 97% for all malaria (95% confidence interval [CI], 82%-99%), 96% for P. vivax malaria (95% CI, 76%-99%), and 100% for P. falciparum malaria (95% CI, 60%-100%). Monthly tafenoquine was safe, well tolerated, and highly effective in preventing P. vivax and multidrug-resistant P. falciparum malaria in Thai soldiers during 6 months of prophylaxis. Copyright 2004 Infectious Diseases Society of America

Targeting a Novel Plasmodium falciparum Purine Recycling Pathway with Specific Immucillins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ting, L; Shi, W; Lewandowicz, A

Plasmodium falciparum is unable to synthesize purine bases and relies upon purine salvage and purine recycling to meet its purine needs. We report that purines formed as products of the polyamine pathway are recycled in a novel pathway in which 5'-methylthioinosine is generated by adenosine deaminase. The action of P. falciparum purine nucleoside phosphorylase is a convergent step of purine salvage, converting both 5'-methylthioinosine and inosine to hypoxanthine. We used accelerator mass spectrometry to verify that 5'-methylthioinosine is an active nucleic acid precursor in P. falciparum. Prior studies have shown that inhibitors of purine salvage enzymes kill malaria, but potentmore » malaria-specific inhibitors of these enzymes have not previously been described. 5'-methylthio-Immucillin-H, a transition state analogue inhibitor that is selective for malarial over human purine nucleoside phosphorylase, kills P. falciparum in culture. Immucillins are currently in clinical trials for other indications and may have application as antimalarials.« less

Response of imported malaria patients to antimalarial medicines in Sri Lanka following malaria elimination.

PubMed

Dharmawardena, Priyani; Rodrigo, Chaturaka; Mendis, Kamini; de A W Gunasekera, W M Kumudu T; Premaratne, Risintha; Ringwald, Pascal; Fernando, Deepika

2017-01-01

After eliminating local malaria transmission and being certified as a malaria-free country, Sri Lanka is facing the challenge of imported malaria. At the same time, the country has the unique opportunity to be a case study for other countries in a similar situation by approaching this issue systematically, guided by evidence. This study demonstrates the importance of developing a mechanism to detect imported malaria and adopting an evidence-based approach to study the resistance of imported malaria to anti-malarial medicines. This is a prospective study of patients diagnosed with imported malaria in Sri Lanka and treated according to the national treatment guidelines, over 24 months (2015/2016). The clinical features, time to diagnosis, origin of the infection, infecting species, parasite density and the treatment given were recorded. All patients were followed up for 28 days, and in the case of Plasmodium vivax and P. ovale infections, the follow up period was extended to 12 months to establish treatment failures and relapses. Fifty nine uncomplicated and 15 severe imported malaria cases were reported in Sri Lanka during the study period. Most of these infections originated in either Sub-Saharan Africa or South and Southeast Asia. Having a P. vivax infection and low parasitic counts were significantly associated with relative diagnostic delay. One of the 14 uncomplicated P. falciparum patients and two of the 12 severe P. falciparum malaria patients who were followed up till day 28 had a late clinical failure. The others responded adequately to treatment both clinically and parasitologically. There was no treatment failure reported amongst any other species. This study, which is the first to assess the therapeutic response of imported malaria in Sri Lanka after elimination, demonstrates that the current antimalarial treatment policies and strategies in Sri Lanka have been effective against infections acquired overseas up until the end of year 2016.

Spatial mapping and prediction of Plasmodium falciparum infection risk among school-aged children in Côte d'Ivoire.

PubMed

Houngbedji, Clarisse A; Chammartin, Frédérique; Yapi, Richard B; Hürlimann, Eveline; N'Dri, Prisca B; Silué, Kigbafori D; Soro, Gotianwa; Koudou, Benjamin G; Assi, Serge-Brice; N'Goran, Eliézer K; Fantodji, Agathe; Utzinger, Jürg; Vounatsou, Penelope; Raso, Giovanna

2016-09-07

In Côte d'Ivoire, malaria remains a major public health issue, and thus a priority to be tackled. The aim of this study was to identify spatially explicit indicators of Plasmodium falciparum infection among school-aged children and to undertake a model-based spatial prediction of P. falciparum infection risk using environmental predictors. A cross-sectional survey was conducted, including parasitological examinations and interviews with more than 5,000 children from 93 schools across Côte d'Ivoire. A finger-prick blood sample was obtained from each child to determine Plasmodium species-specific infection and parasitaemia using Giemsa-stained thick and thin blood films. Household socioeconomic status was assessed through asset ownership and household characteristics. Children were interviewed for preventive measures against malaria. Environmental data were gathered from satellite images and digitized maps. A Bayesian geostatistical stochastic search variable selection procedure was employed to identify factors related to P. falciparum infection risk. Bayesian geostatistical logistic regression models were used to map the spatial distribution of P. falciparum infection and to predict the infection prevalence at non-sampled locations via Bayesian kriging. Complete data sets were available from 5,322 children aged 5-16 years across Côte d'Ivoire. P. falciparum was the predominant species (94.5 %). The Bayesian geostatistical variable selection procedure identified land cover and socioeconomic status as important predictors for infection risk with P. falciparum. Model-based prediction identified high P. falciparum infection risk in the north, central-east, south-east, west and south-west of Côte d'Ivoire. Low-risk areas were found in the south-eastern area close to Abidjan and the south-central and west-central part of the country. The P. falciparum infection risk and related uncertainty estimates for school-aged children in Côte d'Ivoire represent the most up-to-date malaria risk maps. These tools can be used for spatial targeting of malaria control interventions.

Humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice sustain the complex vertebrate life cycle of Plasmodium falciparum malaria.

PubMed

Wijayalath, Wathsala; Majji, Sai; Villasante, Eileen F; Brumeanu, Teodor D; Richie, Thomas L; Casares, Sofia

2014-09-30

Malaria is a deadly infectious disease affecting millions of people in tropical and sub-tropical countries. Among the five species of Plasmodium parasites that infect humans, Plasmodium falciparum accounts for the highest morbidity and mortality associated with malaria. Since humans are the only natural hosts for P. falciparum, the lack of convenient animal models has hindered the understanding of disease pathogenesis and prompted the need of testing anti-malarial drugs and vaccines directly in human trials. Humanized mice hosting human cells represent new pre-clinical models for infectious diseases that affect only humans. In this study, the ability of human-immune-system humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice to sustain infection with P. falciparum was explored. Four week-old DRAG mice were infused with HLA-matched human haematopoietic stem cells (HSC) and examined for reconstitution of human liver cells and erythrocytes. Upon challenge with infectious P. falciparum sporozoites (NF54 strain) humanized DRAG mice were examined for liver stage infection, blood stage infection, and transmission to Anopheles stephensi mosquitoes. Humanized DRAG mice reconstituted human hepatocytes, Kupffer cells, liver endothelial cells, and erythrocytes. Upon intravenous challenge with P. falciparum sporozoites, DRAG mice sustained liver to blood stage infection (average 3-5 parasites/microlitre blood) and allowed transmission to An. stephensi mosquitoes. Infected DRAG mice elicited antibody and cellular responses to the blood stage parasites and self-cured the infection by day 45 post-challenge. DRAG mice represent the first human-immune-system humanized mouse model that sustains the complex vertebrate life cycle of P. falciparum without the need of exogenous injection of human hepatocytes/erythrocytes or P. falciparum parasite adaptation. The ability of DRAG mice to elicit specific human immune responses to P. falciparum parasites may help deciphering immune correlates of protection and to identify protective malaria antigens.

Natural Plasmodium infection in monkeys in the state of Rondônia (Brazilian Western Amazon)

PubMed Central

2013-01-01

Background Simian malaria is still an open question concerning the species of Plasmodium parasites and species of New World monkeys susceptible to the parasites. In addition, the lingering question as to whether these animals are reservoirs for human malaria might become important especially in a scenario of eradication of the disease. To aid in the answers to these questions, monkeys were surveyed for malaria parasite natural infection in the Amazonian state of Rondônia, Brazil, a state with intense environmental alterations due to human activities, which facilitated sampling of the animals. Methods Parasites were detected and identified in DNA from blood of monkeys, by PCR with primers for the 18S rRNA, CSP and MSP1 genes and sequencing of the amplified fragments. Multiplex PCR primers for the 18S rRNA genes were designed for the parasite species Plasmodium falciparum and Plasmodium vivax, Plasmodium malariae/Plasmodium brasilianum and Plasmodium simium. Results An overall infection rate of 10.9% was observed or 20 out 184 monkey specimens surveyed, mostly by P. brasilianum. However, four specimens of monkeys were found infected with P. falciparum, two of them doubly infected with P. brasilianum and P. falciparum. In addition, a species of monkey of the family Aotidae, Aotus nigriceps, is firstly reported here naturally infected with P. brasilianum. None of the monkeys surveyed was found infected with P. simium/P. vivax. Conclusion The rate of natural Plasmodium infection in monkeys in the Brazilian state of Rondônia is in line with previous surveys of simian malaria in the Amazon region. The fact that a monkey species was found that had not previously been described to harbour malaria parasites indicates that the list of monkey species susceptible to Plasmodium infection is yet to be completed. Furthermore, finding monkeys in the region infected with P. falciparum clearly indicates parasite transfer from humans to the animals. Whether this parasite can be transferred back to humans and how persistent the parasite is in monkeys in the wild so to be efficient reservoirs of the disease, is yet to be evaluated. Finding different species of monkeys infected with this parasite species suggests indeed that these animals can act as reservoirs of human malaria. PMID:23731624

Modelling the incidence of Plasmodium vivax and Plasmodium falciparum malaria in Afghanistan 2006-2009.

PubMed

Alegana, Victor A; Wright, Jim A; Nahzat, Sami M; Butt, Waqar; Sediqi, Amad W; Habib, Naeem; Snow, Robert W; Atkinson, Peter M; Noor, Abdisalan M

2014-01-01

Identifying areas that support high malaria risks and where populations lack access to health care is central to reducing the burden in Afghanistan. This study investigated the incidence of Plasmodium vivax and Plasmodium falciparum using routine data to help focus malaria interventions. To estimate incidence, the study modelled utilisation of the public health sector using fever treatment data from the 2012 national Malaria Indicator Survey. A probabilistic measure of attendance was applied to population density metrics to define the proportion of the population within catchment of a public health facility. Malaria data were used in a Bayesian spatio-temporal conditional-autoregressive model with ecological or environmental covariates, to examine the spatial and temporal variation of incidence. From the analysis of healthcare utilisation, over 80% of the population was within 2 hours' travel of the nearest public health facility, while 64.4% were within 30 minutes' travel. The mean incidence of P. vivax in 2009 was 5.4 (95% Crl 3.2-9.2) cases per 1000 population compared to 1.2 (95% Crl 0.4-2.9) cases per 1000 population for P. falciparum. P. vivax peaked in August while P. falciparum peaked in November. 32% of the estimated 30.5 million people lived in regions where annual incidence was at least 1 case per 1,000 population of P. vivax; 23.7% of the population lived in areas where annual P. falciparum case incidence was at least 1 per 1000. This study showed how routine data can be combined with household survey data to model malaria incidence. The incidence of both P. vivax and P. falciparum in Afghanistan remain low but the co-distribution of both parasites and the lag in their peak season provides challenges to malaria control in Afghanistan. Future improved case definition to determine levels of imported risks may be useful for the elimination ambitions in Afghanistan.

Modelling the Incidence of Plasmodium vivax and Plasmodium falciparum Malaria in Afghanistan 2006–2009

PubMed Central

Alegana, Victor A.; Wright, Jim A.; Nahzat, Sami M.; Butt, Waqar; Sediqi, Amad W.; Habib, Naeem; Snow, Robert W.; Atkinson, Peter M.; Noor, Abdisalan M.

2014-01-01

Background Identifying areas that support high malaria risks and where populations lack access to health care is central to reducing the burden in Afghanistan. This study investigated the incidence of Plasmodium vivax and Plasmodium falciparum using routine data to help focus malaria interventions. Methods To estimate incidence, the study modelled utilisation of the public health sector using fever treatment data from the 2012 national Malaria Indicator Survey. A probabilistic measure of attendance was applied to population density metrics to define the proportion of the population within catchment of a public health facility. Malaria data were used in a Bayesian spatio-temporal conditional-autoregressive model with ecological or environmental covariates, to examine the spatial and temporal variation of incidence. Findings From the analysis of healthcare utilisation, over 80% of the population was within 2 hours’ travel of the nearest public health facility, while 64.4% were within 30 minutes’ travel. The mean incidence of P. vivax in 2009 was 5.4 (95% Crl 3.2–9.2) cases per 1000 population compared to 1.2 (95% Crl 0.4–2.9) cases per 1000 population for P. falciparum. P. vivax peaked in August while P. falciparum peaked in November. 32% of the estimated 30.5 million people lived in regions where annual incidence was at least 1 case per 1,000 population of P. vivax; 23.7% of the population lived in areas where annual P. falciparum case incidence was at least 1 per 1000. Conclusion This study showed how routine data can be combined with household survey data to model malaria incidence. The incidence of both P. vivax and P. falciparum in Afghanistan remain low but the co-distribution of both parasites and the lag in their peak season provides challenges to malaria control in Afghanistan. Future improved case definition to determine levels of imported risks may be useful for the elimination ambitions in Afghanistan. PMID:25033452

Impairment of the Plasmodium falciparum erythrocytic cycle induced by angiotensin peptides.

PubMed

Saraiva, Victor Barbosa; de Souza Silva, Leandro; Ferreira-DaSilva, Claudio Teixeira; da Silva-Filho, João Luiz; Teixeira-Ferreira, André; Perales, Jonas; Souza, Mariana Conceição; Henriques, Maria das Graças; Caruso-Neves, Celso; de Sá Pinheiro, Ana Acacia

2011-02-18

Plasmodium falciparum causes the most serious complications of malaria and is a public health problem worldwide with over 2 million deaths each year. The erythrocyte invasion mechanisms by Plasmodium sp. have been well described, however the physiological aspects involving host components in this process are still poorly understood. Here, we provide evidence for the role of renin-angiotensin system (RAS) components in reducing erythrocyte invasion by P. falciparum. Angiotensin II (Ang II) reduced erythrocyte invasion in an enriched schizont culture of P. falciparum in a dose-dependent manner. Using mass spectroscopy, we showed that Ang II was metabolized by erythrocytes to Ang IV and Ang-(1-7). Parasite infection decreased Ang-(1-7) and completely abolished Ang IV formation. Similar to Ang II, Ang-(1-7) decreased the level of infection in an A779 (specific antagonist of Ang-(1-7) receptor, MAS)-sensitive manner. 10(-7) M PD123319, an AT(2) receptor antagonist, partially reversed the effects of Ang-(1-7) and Ang II. However, 10(-6) M losartan, an antagonist of the AT(1) receptor, had no effect. Gs protein is a crucial player in the Plasmodium falciparum blood cycle and angiotensin peptides can modulate protein kinase A (PKA) activity; 10(-8) M Ang II or 10(-8) M Ang-(1-7) inhibited this activity in erythrocytes by 60% and this effect was reversed by 10(-7) M A779. 10(-6) M dibutyryl-cAMP increased the level of infection and 10(-7) M PKA inhibitor decreased the level of infection by 30%. These results indicate that the effect of Ang-(1-7) on P. falciparum blood stage involves a MAS-mediated PKA inhibition. Our results indicate a crucial role for Ang II conversion into Ang-(1-7) in controlling the erythrocytic cycle of the malaria parasite, adding new functions to peptides initially described to be involved in the regulation of vascular tonus.

Ned-19 inhibition of parasite growth and multiplication suggests a role for NAADP mediated signalling in the asexual development of Plasmodium falciparum.

PubMed

Suárez-Cortés, Pablo; Gambara, Guido; Favia, Annarita; Palombi, Fioretta; Alano, Pietro; Filippini, Antonio

2017-09-12

Although malaria is a preventable and curable human disease, millions of people risk to be infected by the Plasmodium parasites and to develop this illness. Therefore, there is an urgent need to identify new anti-malarial drugs. Ca 2+ signalling regulates different processes in the life cycle of Plasmodium falciparum, representing a suitable target for the development of new drugs. This study investigated for the first time the effect of a highly specific inhibitor of nicotinic acid adenine dinucleotide phosphate (NAADP)-induced Ca 2+ release (Ned-19) on P. falciparum, revealing the inhibitory effect of this compound on the blood stage development of this parasite. Ned-19 inhibits both the transition of the parasite from the early to the late trophozoite stage and the ability of the late trophozoite to develop to the multinucleated schizont stage. In addition, Ned-19 affects spontaneous intracellular Ca 2+ oscillations in ring and trophozoite stage parasites, suggesting that the observed inhibitory effects may be associated to regulation of intracellular Ca 2+ levels. This study highlights the inhibitory effect of Ned-19 on progression of the asexual life cycle of P. falciparum. The observation that Ned-19 inhibits spontaneous Ca 2+ oscillations suggests a potential role of NAADP in regulating Ca 2+ signalling of P. falciparum.

Therapeutic efficacy trial of artemisinin-based combination therapy for the treatment of uncomplicated malaria and investigation of mutations in k13 propeller domain in Togo, 2012-2013.

PubMed

Dorkenoo, Améyo M; Yehadji, Degninou; Agbo, Yao M; Layibo, Yao; Agbeko, Foli; Adjeloh, Poukpessi; Yakpa, Kossi; Sossou, Efoe; Awokou, Fantchè; Ringwald, Pascal

2016-06-22

Since 2005, the Togo National Malaria Control Programme has recommended two different formulations of artemisinin-based combination therapy (ACT), artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL), for the treatment of uncomplicated malaria. Regular efficacy monitoring of these two combinations is conducted every 2 or 3 years. This paper reports the latest efficacy assessment results and the investigation of mutations in the k13 propeller domain. The study was conducted in 2012-2013 on three sentinel sites of Togo (Lomé, Sokodé and Niamtougou). Children aged 6-59 months, who were symptomatically infected with Plasmodium falciparum, were treated with either AL (Coartem(®), Novartis Pharma, Switzerland) or ASAQ (Co-Arsucam(®), Sanofi Aventis, France). The WHO standard protocol for anti-malarial treatment evaluation was used. The primary end-point was 28-day adequate clinical and parasitological response (ACPR), corrected to exclude reinfection using polymerase-chain reaction (PCR) genotyping. A total of 523 children were included in the study. PCR-corrected ACPR was 96.3-100 % for ASAQ and 97-100 % for AL across the three study sites. Adverse events were negligible: 0-4.8 % across all sites, for both artemisinin-based combinations. Upon investigation of mutations in the k13 propeller domain, only 9 (1.8 %) mutations were reported, three in each site. All mutant parasites were cleared before day 3. All day 3 positive patients were infected with k13 wild type parasites. The efficacy of AL and ASAQ remains high in Togo, and both drugs are well tolerated. ASAQ and AL would be recommended for the treatment of uncomplicated malaria in Togo.

A comprehensive model for assessment of liver stage therapies targeting Plasmodium vivax and Plasmodium falciparum.

PubMed

Roth, Alison; Maher, Steven P; Conway, Amy J; Ubalee, Ratawan; Chaumeau, Victor; Andolina, Chiara; Kaba, Stephen A; Vantaux, Amélie; Bakowski, Malina A; Luque, Richard Thomson; Adapa, Swamy Rakesh; Singh, Naresh; Barnes, Samantha J; Cooper, Caitlin A; Rouillier, Mélanie; McNamara, Case W; Mikolajczak, Sebastian A; Sather, Noah; Witkowski, Benoît; Campo, Brice; Kappe, Stefan H I; Lanar, David E; Nosten, François; Davidson, Silas; Jiang, Rays H Y; Kyle, Dennis E; Adams, John H

2018-05-09

Malaria liver stages represent an ideal therapeutic target with a bottleneck in parasite load and reduced clinical symptoms; however, current in vitro pre-erythrocytic (PE) models for Plasmodium vivax and P. falciparum lack the efficiency necessary for rapid identification and effective evaluation of new vaccines and drugs, especially targeting late liver-stage development and hypnozoites. Herein we report the development of a 384-well plate culture system using commercially available materials, including cryopreserved primary human hepatocytes. Hepatocyte physiology is maintained for at least 30 days and supports development of P. vivax hypnozoites and complete maturation of P. vivax and P. falciparum schizonts. Our multimodal analysis in antimalarial therapeutic research identifies important PE inhibition mechanisms: immune antibodies against sporozoite surface proteins functionally inhibit liver stage development and ion homeostasis is essential for schizont and hypnozoite viability. This model can be implemented in laboratories in disease-endemic areas to accelerate vaccine and drug discovery research.

Capacitive malaria aptasensor using Plasmodium falciparum glutamate dehydrogenase as target antigen in undiluted human serum.

PubMed

Singh, Naveen K; Arya, Sunil K; Estrela, Pedro; Goswami, Pranab

2018-06-08

A capacitive aptasensor for detecting the malaria biomarker, Plasmodium falciparum glutamate dehydrogenase (PfGDH), directly in human serum samples developed. A thiolated ssDNA aptamer (NG3) that binds specifically to PfGDH antigen with high affinity (K d = 79 nM) was used to develop the aptasensor. The aptasensor produced capacitance response at an optimized frequency of 2 Hz in a non-Faradaic electrochemical impedance based signal transduction platform. The aptasensor exhibited a wide dynamic range of 100 fM-100 nM with a limits of detection of 0.77 pM in serum samples. The interference from other predominant malarial biomarkers, namely, Plasmodium falciparum -lactate dehydrogenase and -histidine rich protein-II on the aptasensor was negligible. This PfGDH aptasensor with highly sensitive and label free detection capability has great application potential for diagnosis of asymptotic malaria and monitoring the regression of malaria during treatment regime with antimalarial drugs. Copyright © 2018 Elsevier B.V. All rights reserved.

Genetic modification of Anopheles stephensi for resistance to multiple Plasmodium falciparum strains does not influence susceptibility to o'nyong'nyong virus or insecticides, or Wolbachia-mediated resistance to the malaria parasite.

PubMed

Pike, Andrew; Dimopoulos, George

2018-01-01

Mosquitoes that have been genetically engineered for resistance to human pathogens are a potential new tool for controlling vector-borne disease. However, genetic modification may have unintended off-target effects that could affect the mosquitoes' utility for disease control. We measured the resistance of five genetically modified Plasmodium-suppressing Anopheles stephensi lines to o'nyong'nyong virus, four classes of insecticides, and diverse Plasmodium falciparum field isolates and characterized the interactions between our genetic modifications and infection with the bacterium Wolbachia. The genetic modifications did not alter the mosquitoes' resistance to either o'nyong'nyong virus or insecticides, and the mosquitoes were equally resistant to all tested P. falciparum strains, regardless of Wolbachia infection status. These results indicate that mosquitoes can be genetically modified for resistance to malaria parasite infection and remain compatible with other vector-control measures without becoming better vectors for other pathogens.

Host age and Plasmodium falciparum multiclonality are associated with gametocyte prevalence: a 1-year prospective cohort study.

PubMed

Adomako-Ankomah, Yaw; Chenoweth, Matthew S; Tocker, Aaron M; Doumbia, Saibou; Konate, Drissa; Doumbouya, Mory; Keita, Abdoul S; Anderson, Jennifer M; Fairhurst, Rick M; Diakite, Mahamadou; Miura, Kazutoyo; Long, Carole A

2017-11-21

Since Plasmodium falciparum transmission relies exclusively on sexual-stage parasites, several malaria control strategies aim to disrupt this step of the life cycle. Thus, a better understanding of which individuals constitute the primary gametocyte reservoir within an endemic population, and the temporal dynamics of gametocyte carriage, especially in seasonal transmission settings, will not only support the effective implementation of current transmission control programmes, but also inform the design of more targeted strategies. A 1-year prospective cohort study was initiated in June 2013 with the goal of assessing the longitudinal dynamics of P. falciparum gametocyte carriage in a village in Mali with intense seasonal malaria transmission. A cohort of 500 individuals aged 1-65 years was recruited for this study. Gametocyte prevalence was measured monthly using Pfs25-specific RT-PCR, and analysed for the effects of host age and gender, seasonality, and multiclonality of P. falciparum infection over 1 year. Most P. falciparum infections (51-89%) in this population were accompanied by gametocytaemia throughout the 1-year period. Gametocyte prevalence among P. falciparum-positive individuals (proportion of gametocyte positive infections) was associated with age (p = 0.003) but not with seasonality (wet vs. dry) or gender. The proportion of gametocyte positive infections were similarly high in children aged 1-17 years (74-82% on median among 5 age groups), while older individuals had relatively lower proportion, and those aged > 35 years (median of 43%) had significantly lower than those aged 1-17 years (p < 0.05). Plasmodium falciparum-positive individuals with gametocytaemia were found to have significantly higher P. falciparum multiclonality than those without gametocytaemia (p < 0.033 in two different analyses). Taken together, these results suggest that a substantial proportion of Pf-positive individuals carries gametocytes throughout the year, and that age is a significant determinant of gametocyte prevalence among these P. falciparum-positive individuals. Furthermore, the presence of multiple P. falciparum genotypes in an infection, a common feature of P. falciparum infections in high transmission areas, is associated with gametocyte prevalence.

Plasmodium knowlesi Skeleton-Binding Protein 1 Localizes to the ‘Sinton and Mulligan’ Stipplings in the Cytoplasm of Monkey and Human Erythrocytes

PubMed Central

Lucky, Amuza Byaruhanga; Sakaguchi, Miako; Katakai, Yuko; Kawai, Satoru; Yahata, Kazuhide; Templeton, Thomas J.

2016-01-01

The malaria parasite, Plasmodium, exports protein products to the infected erythrocyte to introduce modifications necessary for the establishment of nutrient acquisition and surface display of host interaction ligands. Erythrocyte remodeling impacts parasite virulence and disease pathology and is well documented for the human malaria parasite Plasmodium falciparum, but has been less described for other Plasmodium species. For P. falciparum, the exported protein skeleton-binding protein 1 (PfSBP1) is involved in the trafficking of erythrocyte surface ligands and localized to membranous structures within the infected erythrocyte, termed Maurer's clefts. In this study, we analyzed SBP1 orthologs across the Plasmodium genus by BLAST analysis and conserved gene synteny, which were also recently described by de Niz et al. (2016). To evaluate the localization of an SBP1 ortholog, we utilized the zoonotic malaria parasite, Plasmodium knowlesi. Immunofluorescence assay of transgenic P. knowlesi parasites expressing epitope-tagged recombinant PkSBP1 revealed a punctate staining pattern reminiscent of Maurer's clefts, following infection of either monkey or human erythrocytes. The recombinant PkSBP1-positive puncta co-localized with Giemsa-stained structures, known as ‘Sinton and Mulligan’ stipplings. Immunoelectron microscopy also showed that recombinant PkSBP1 localizes within or on the membranous structures akin to the Maurer's clefts. The recombinant PkSBP1 expressed in P. falciparum-infected erythrocytes co-localized with PfSBP1 at the Maurer's clefts, indicating an analogous trafficking pattern. A member of the P. knowlesi 2TM protein family was also expressed and localized to membranous structures in infected monkey erythrocytes. These results suggest that the trafficking machinery and induced erythrocyte cellular structures of P. knowlesi are similar following infection of both monkey and human erythrocytes, and are conserved with P. falciparum. PMID:27732628

Mefloquine adverse effects with atypical facial lesions in an overweight patient.

PubMed

Descloux, Elodie; De Monbrison, Frédérique; Basselin, Cécile; Vial, Thierry; Peyron, François

2010-09-01

The recommended dosage of mefloquine to treat Plasmodium falciparum infection is 25 mg/kg, with no recommendation for dosage exceeding 1500 mg. We describe an original case of adverse reaction to mefloquine in an overweight patient. Case report. A 32-year-old woman weighing 139 kg presented with uncomplicated P. falciparum infection after returning from Cameroon. She received 3250 mg of mefloquine (i.e. 23 mg/kg) administered in four doses. On day 2, she developed neuropsychiatric disorders and facial lesions. Nasal mucocutaneous vesicles and bullae, depressive mood, mild thrombocytopenia and hepatic cytolysis were evidenced. Parasitemia was negative. Recovery was complete on day 17. High mefloquine serum levels were measured (8.030 mg/L on day 3, 6.880 mg/L on day 8, and 3.370 mg/L on day 17). The causal relationship between mefloquine and the occurrence of these adverse effects is probable. However, as no viral or bacteriological investigations were performed, the drug responsibility remains uncertain. Mefloquine-induced bullous and facial lesions reversible upon drug withdrawal have already been described. The associated neuropsychiatric symptoms were strongly suggestive of mefloquine adverse effects, as such events are more frequently observed in cases of overdosage. Our case emphasizes the difficulties of dosage adaptation in overweight patients. Copyright © 2010 Elsevier Ltd. All rights reserved.

The spectrum of retinopathy in adults with Plasmodium falciparum malaria

PubMed Central

Maude, Richard J.; Beare, Nicholas A.V.; Sayeed, Abdullah Abu; Chang, Christina C.; Charunwatthana, Prakaykaew; Faiz, M. Abul; Hossain, Amir; Yunus, Emran Bin; Hoque, M. Gofranul; Hasan, Mahtab Uddin; White, Nicholas J.; Day, Nicholas P.J.; Dondorp, Arjen M.

2009-01-01

Summary A specific retinopathy has been described in African children with cerebral malaria, but in adults this has not been extensively studied. Since the structure and function of the retinal vasculature greatly resembles the cerebral vasculature, study of retinal changes can reveal insights into the pathophysiology of cerebral malaria. A detailed observational study of malarial retinopathy in Bangladeshi adults was performed using high-definition portable retinal photography. Retinopathy was present in 17/27 adults (63%) with severe malaria and 14/20 adults (70%) with cerebral malaria. Moderate or severe retinopathy was more frequent in cerebral malaria (11/20, 55%) than in uncomplicated malaria (3/15, 20%; P = 0.039), bacterial sepsis (0/5, 0%; P = 0.038) or healthy controls (0/18, 0%; P < 0.001). The spectrum of malarial retinopathy was similar to that previously described in African children, but no vessel discolouration was observed. The severity of retinal whitening correlated with admission venous plasma lactate (P = 0.046), suggesting that retinal ischaemia represents systemic ischaemia. In conclusion, retinal changes related to microvascular obstruction were common in adults with severe falciparum malaria and correlated with disease severity and coma, suggesting that a compromised microcirculation has important pathophysiological significance in severe and cerebral malaria. Portable retinal photography has potential as a valuable tool to study malarial retinopathy. PMID:19344925

Asymptomatic malaria correlates with anaemia in pregnant women at Ouagadougou, Burkina Faso.

PubMed

Douamba, Zoenabo; Bisseye, Cyrille; Djigma, Florencia W; Compaoré, Tegwinde R; Bazie, Valérie Jean Telesphore; Pietra, Virginio; Nikiema, Jean-Baptiste; Simpore, Jacques

2012-01-01

Sub-Saharan Africa records each year about thirty-two million pregnant women living in areas of high transmission of Plasmodium falciparum causing malaria. The aim of this study was to carve out the prevalence of asymptomatic malaria among pregnant women and to emphasize its influence on haematological markers. The prevalence of Plasmodium falciparum asymptomatic infection among pregnant women was 30% and 24% with rapid detection test (RDT) and microscopy, respectively. The prevalence of P. falciparum asymptomatic malaria was reduced among pregnant women using sulfadoxine-pyrimethamine's intermittent preventive treatment and 61% of them were anaemic. Anaemia was significantly more common in women infected with P. falciparum compared with the uninfected pregnant women. Most of the women had normal levels of homocysteine and low levels of folate, respectively. Therefore, the systematic diagnosis of malaria should be introduced to pregnant women as a part of the antenatal care.

Limonene Arrests Parasite Development and Inhibits Isoprenylation of Proteins in Plasmodium falciparum

PubMed Central

Moura, Ivan Cruz; Wunderlich, Gerhard; Uhrig, Maria L.; Couto, Alicia S.; Peres, Valnice J.; Katzin, Alejandro M.; Kimura, Emília A.

2001-01-01

Isoprenylation is an essential protein modification in eukaryotic cells. Herein, we report that in Plasmodium falciparum, a number of proteins were labeled upon incubation of intraerythrocytic forms with either [3H]farnesyl pyrophosphate or [3H]geranylgeranyl pyrophosphate. By thin-layer chromatography, we showed that attached isoprenoids are partially modified to dolichol and other, uncharacterized, residues, confirming active isoprenoid metabolism in this parasite. Incubation of blood-stage P. falciparum treated with the isoprenylation inhibitor limonene significantly decreased the parasites' progression from the ring stage to the trophozoite stage and at 1.22 mM, 50% of the parasites died after the first cycle. Using Ras- and Rap-specific monoclonal antibodies, putative Rap and Ras proteins of P. falciparum were immunoprecipitated. Upon treatment with 0.5 mM limonene, isoprenylation of these proteins was significantly decreased, possibly explaining the observed arrest of parasite development. PMID:11502528

Purification and partial characterization of PfHRP-II protein of Plasmodium falciparum.

PubMed

Ghimire, Prakash; Samantaray, J C; Mirdha, B R; Patra, A K; Panda, A K

2003-12-01

The human malarial parasite Plasmodium falciparum secretes various intra-and extra-cellular proteins during its asexual life cycle in human RBC. Histidine rich protein-II (HRP-II) is one of the most prominent proteins, found to be secreted by P. falciparum throughout the asexual cycle with the peak during mature schizont stage of the parasite development in human IRBC. The high histidine content (35% of the total amino acids in protein) of this protein suggested the potential to bind divalent metal ions. We have demonstrated by metal chelate chromatography, an extraordinary capacity of HRP-II to bind nickel ions (Ni++) and employed this characteristic to purify the extra-cellular HRP-II protein secreted by P. falciparum from culture supernatant. The identity of the purified protein was verified by the relative molecular weight on SDS-PAGE, by reacting with polyclonal antibodies directed against it using Western blot technique.

Crystal Structure Analyses of the Fosmidomycin-Target Enzyme from Plasmodium Falciparum

NASA Astrophysics Data System (ADS)

Umeda, Tomonobu; Kusakabe, Yoshio; Tanaka, Nobutada

The human malaria parasite Plasmodium falciparum is responsible for the death of more than a million people each year. Fosmidomycin has proved to be efficient in the treatment of P. falciparum malaria through the inhibition of 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), an enzyme of the non-mevalonate pathway of isoprenoid biosynthesis, which is absent in humans. Crystal structure analyses of P. falciparum DXR (PfDXR) revealed that (i) an intrinsic flexibility of the PfDXR molecule accounts for the induced-fit movement to accommodate the bound inhibitor in the active site, and (ii) a cis arrangement of the oxygen atoms of the hydroxamate group of the bound inhibitor is essential for tight binding of the inhibitor to the active site metal. We believe that our study will serve as a useful guide to develop more potent PfDXR inhibitors.

Artemisinin Resistance-Associated Polymorphisms at the K13-Propeller Locus Are Absent in Plasmodium falciparum Isolates from Haiti

PubMed Central

Carter, Tamar E.; Boulter, Alexis; Existe, Alexandre; Romain, Jean R.; St. Victor, Jean Yves; Mulligan, Connie J.; Okech, Bernard A.

2015-01-01

Antimalarial drugs are a key tool in malaria elimination programs. With the emergence of artemisinin resistance in southeast Asia, an effort to identify molecular markers for surveillance of resistant malaria parasites is underway. Non-synonymous mutations in the kelch propeller domain (K13-propeller) in Plasmodium falciparum have been associated with artemisinin resistance in samples from southeast Asia, but additional studies are needed to characterize this locus in other P. falciparum populations with different levels of artemisinin use. Here, we sequenced the K13-propeller locus in 82 samples from Haiti, where limited government oversight of non-governmental organizations may have resulted in low-level use of artemisinin-based combination therapies. We detected a single-nucleotide polymorphism (SNP) at nucleotide 1,359 in a single isolate. Our results contribute to our understanding of the global genomic diversity of the K13-propeller locus in P. falciparum populations. PMID:25646258

A Plasmodium falciparum strain expressing GFP throughout the parasite's life-cycle.

PubMed

Talman, Arthur M; Blagborough, Andrew M; Sinden, Robert E

2010-02-10

The human malaria parasite Plasmodium falciparum is responsible for the majority of malaria-related deaths. Tools allowing the study of the basic biology of P. falciparum throughout the life cycle are critical to the development of new strategies to target the parasite within both human and mosquito hosts. We here present 3D7HT-GFP, a strain of P. falciparum constitutively expressing the Green Fluorescent Protein (GFP) throughout the life cycle, which has retained its capacity to complete sporogonic development. The GFP expressing cassette was inserted in the Pf47 locus. Using this transgenic strain, parasite tracking and population dynamics studies in mosquito stages and exo-erythrocytic schizogony is greatly facilitated. The development of 3D7HT-GFP will permit a deeper understanding of the biology of parasite-host vector interactions, and facilitate the development of high-throughput malaria transmission assays and thus aid development of new intervention strategies against both parasite and mosquito.

Versatile control of Plasmodium falciparum gene expression with an inducible protein-RNA interaction

PubMed Central

Goldfless, Stephen J.; Wagner, Jeffrey C.; Niles, Jacquin C.

2014-01-01

The available tools for conditional gene expression in Plasmodium falciparum are limited. Here, to enable reliable control of target gene expression, we build a system to efficiently modulate translation. We overcame several problems associated with other approaches for regulating gene expression in P. falciparum. Specifically, our system functions predictably across several native and engineered promoter contexts, and affords control over reporter and native parasite proteins irrespective of their subcellular compartmentalization. Induction and repression of gene expression are rapid, homogeneous, and stable over prolonged periods. To demonstrate practical application of our system, we used it to reveal direct links between antimalarial drugs and their native parasite molecular target. This is an important out come given the rapid spread of resistance, and intensified efforts to efficiently discover and optimize new antimalarial drugs. Overall, the studies presented highlight the utility of our system for broadly controlling gene expression and performing functional genetics in P. falciparum. PMID:25370483

A new method for culturing Plasmodium falciparum shows replication at the highest erythrocyte densities

NASA Technical Reports Server (NTRS)

Li, Tao; Glushakova, Svetlana; Zimmerberg, Joshua

2003-01-01

Plasmodium falciparum replicates poorly in erythrocyte densities greater than a hematocrit of 20%. A new method to culture the major malaria parasite was developed by using a hollow fiber bioreactor that preserves healthy erythrocytes at hematocrit up to 100%. P. falciparum replicated equally well at all densities studied. This method proved advantageous for large-scale preparation of parasitized erythrocytes (and potentially immunogens thereof), because high yields ( approximately 10(10) in 4 days) could be prepared with less cost and labor. Concomitantly, secreted proteins were concentrated by molecular sieving during culture, perhaps contributing to the parasitemic limit of 8%-12% with the 3D7 strain. The finding that P. falciparum can replicate at packed erythrocyte densities suggests that this system may be useful for study of the pathogenesis of fatal cerebral malaria, of which one feature is densely packed blood cells in brain microvasculature.

Estimating the parasitaemia of Plasmodium falciparum: experience from a national EQA scheme

PubMed Central

2013-01-01

Background To examine performance of the identification and estimation of percentage parasitaemia of Plasmodium falciparum in stained blood films distributed in the UK National External Quality Assessment Scheme (UKNEQAS) Blood Parasitology Scheme. Methods Analysis of performance for the diagnosis and estimation of the percentage parasitaemia of P. falciparum in Giemsa-stained thin blood films was made over a 15-year period to look for trends in performance. Results An average of 25% of participants failed to estimate the percentage parasitaemia, 17% overestimated and 8% underestimated, whilst 5% misidentified the malaria species present. Conclusions Although the results achieved by participants for other blood parasites have shown an overall improvement, the level of performance for estimation of the parasitaemia of P. falciparum remains unchanged over 15 years. Possible reasons include incorrect calculation, not examining the correct part of the film and not examining an adequate number of microscope fields. PMID:24261625

Characteristics of Travel-Related Severe Plasmodium vivax and Plasmodium falciparum Malaria in Individuals Hospitalized at a Tertiary Referral Center in Lima, Peru.

PubMed

Llanos-Chea, Fiorella; Martínez, Dalila; Rosas, Angel; Samalvides, Frine; Vinetz, Joseph M; Llanos-Cuentas, Alejandro

2015-12-01

Severe Plasmodium falciparum malaria is uncommon in South America. Lima, Peru, while not endemic for malaria, is home to specialized centers for infectious diseases that admit and manage patients with severe malaria (SM), all of whom contracted infection during travel. This retrospective study describes severe travel-related malaria in individuals admitted to one tertiary care referral hospital in Lima, Peru; severity was classified based on criteria published by the World Health Organization in 2000. Data were abstracted from medical records of patients with SM admitted to Hospital Nacional Cayetano Heredia from 2006 to 2011. Of 33 SM cases with complete clinical data, the mean age was 39 years and the male/female ratio was 2.8. Most cases were contracted in known endemic regions within Peru: Amazonia (47%), the central jungle (18%), and the northern coast (12%); cases were also found in five (15%) travelers returning from Africa. Plasmodium vivax was most commonly identified (71%) among the severe infections, followed by P. falciparum (18%); mixed infections composed 11% of the group. Among the criteria of severity, jaundice was most common (58%), followed by severe thrombocytopenia (47%), hyperpyrexia (32%), and shock (15%). Plasmodium vivax mono-infection predominated as the etiology of SM in cases acquired in Peru. © The American Society of Tropical Medicine and Hygiene.

Chloroquine diphosphate bearing dextran nanoparticles augmented drug delivery and overwhelmed drug resistance in Plasmodium falciparum parasites.

PubMed

Kashyap, Aman; Kaur, Rupinder; Baldi, Ashish; Jain, Upendra Kumar; Chandra, Ramesh; Madan, Jitender

2018-07-15

Chloroquine diphosphate (CHQ) is primarily used for the treatment of Plasmodium falciparum malaria at the dose of 500mg orally or 10mg/kg parenterally. However, point mutations in Plasmodiumfalciparum chloroquine resistance transporter (PfCRT) protein and Plasmodium falciparum multidrug resistance protein 1 (Pfmdr1) localized in digestive vacuole membrane, are responsible for CHQ resistance. Therefore, in present investigation, dextran nanoparticles bearing chloroquine diphosphate (CHQ-DEX-NPs) were formulated by solvent diffusion method of size below 70nm with zeta-potential of -20.1±3.2mV. FT-IR, DSC and PXRD techniques confirmed the successful loading of drug in nanomatrix system with amorphous attributes. In vitro drug release analysis indicated the Higuchi pattern with diffusion controlled drug release. The IC 50 of CHQ-DEX-NPs in sensitive (3D7) and resistant (RKL9) Plasmodium falciparum strains was estimated to be 0.031-μg/ml and 0.13-μg/ml significantly lower than 0.059-μg/ml and 0.36-μg/ml of CHQ. The augmented therapeutic efficacy of CHQ-DEX-NPs may be credited to deposition of tailored nanoparticles in food vacuoles of malaria parasites owing to the affinity of parasite towards DEX that consequently lower the drug resistance and improved the therapeutic index. In conclusion, CHQ-DEX-NPs must be evaluated under a set of stringent in vivo parameters to establish its therapeutic efficacy in preclinical model. Copyright © 2018 Elsevier B.V. All rights reserved.

In-Silico molecular docking and simulation studies on novel chalcone and flavone hybrid derivatives with 1, 2, 3-triazole linkage as vital inhibitors of Plasmodium falciparum dihydroorotate dehydrogenase.

PubMed

Thillainayagam, Mahalakshmi; Malathi, Kullappan; Ramaiah, Sudha

2017-11-27

The structural motifs of chalcones, flavones, and triazoles with varied substitutions have been studied for the antimalarial activity. In this study, 25 novel derivatives of chalcone and flavone hybrid derivatives with 1, 2, 3-triazole linkage are docked with Plasmodium falciparum dihydroorotate dehydrogenase to establish their inhibitory activity against Plasmodium falciparum. The best binding conformation of the ligands at the catalytic site of dihydroorotate dehydrogenase are selected to characterize the best bound ligand using the best consensus score and the number of hydrogen bond interactions. The ligand namely (2E)-3-(4-{[1-(3-chloro-4-fluorophenyl)-1H-1, 2, 3-triazol-4-yl]methoxy}-3-methoxyphenyl-1-(2-hydroxy-4,6-dimethoxyphenyl)prop-2-en-1-one, is one the among the five best docked ligands, which interacts with the protein through nine hydrogen bonds and with a consensus score of five. To refine and confirm the docking study results, the stability of complexes is verified using Molecular Dynamics Simulations, Molecular Mechanics /Poisson-Boltzmann Surface Area free binding energy analysis, and per residue contribution for the binding energy. The study implies that the best docked Plasmodium falciparum dihydroorotate dehydrogenase-ligand complex is having high negative binding energy, most stable, compact, and rigid with nine hydrogen bonds. The study provides insight for the optimization of chalcone and flavone hybrids with 1, 2, 3-triazole linkage as potent inhibitors.

Contrasting ex vivo efficacies of "reversed chloroquine" compounds in chloroquine-resistant Plasmodium falciparum and P. vivax isolates.

PubMed

Wirjanata, Grennady; Sebayang, Boni F; Chalfein, Ferryanto; Prayoga; Handayuni, Irene; Noviyanti, Rintis; Kenangalem, Enny; Poespoprodjo, Jeanne Rini; Burgess, Steven J; Peyton, David H; Price, Ric N; Marfurt, Jutta

2015-09-01

Chloroquine (CQ) has been the mainstay of malaria treatment for more than 60 years. However, the emergence and spread of CQ resistance now restrict its use to only a few areas where malaria is endemic. The aim of the present study was to investigate whether a novel combination of a CQ-like moiety and an imipramine-like pharmacophore can reverse CQ resistance ex vivo. Between March to October 2011 and January to September 2013, two "reversed chloroquine" (RCQ) compounds (PL69 and PL106) were tested against multidrug-resistant field isolates of Plasmodium falciparum (n = 41) and Plasmodium vivax (n = 45) in Papua, Indonesia, using a modified ex vivo schizont maturation assay. The RCQ compounds showed high efficacy against both CQ-resistant P. falciparum and P. vivax field isolates. For P. falciparum, the median 50% inhibitory concentrations (IC50s) were 23.2 nM for PL69 and 26.6 nM for PL106, compared to 79.4 nM for unmodified CQ (P < 0.001 and P = 0.036, respectively). The corresponding values for P. vivax were 19.0, 60.0, and 60.9 nM (P < 0.001 and P = 0.018, respectively). There was a significant correlation between IC50s of CQ and PL69 (Spearman's rank correlation coefficient [r s] = 0.727, P < 0.001) and PL106 (rs = 0.830, P < 0.001) in P. vivax but not in P. falciparum. Both RCQs were equally active against the ring and trophozoite stages of P. falciparum, but in P. vivax, PL69 and PL106 showed less potent activity against trophozoite stages (median IC50s, 130.2 and 172.5 nM) compared to ring stages (median IC50s, 17.6 and 91.3 nM). RCQ compounds have enhanced ex vivo activity against CQ-resistant clinical isolates of P. falciparum and P. vivax, suggesting the potential use of reversal agents in antimalarial drug development. Interspecies differences in RCQ compound activity may indicate differences in CQ pharmacokinetics between the two Plasmodium species. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

K13-Propeller Polymorphisms in Plasmodium falciparum Parasites From Sub-Saharan Africa

PubMed Central

Kamau, Edwin; Campino, Susana; Amenga-Etego, Lucas; Drury, Eleanor; Ishengoma, Deus; Johnson, Kimberly; Mumba, Dieudonne; Kekre, Mihir; Yavo, William; Mead, Daniel; Bouyou-Akotet, Marielle; Apinjoh, Tobias; Golassa, Lemu; Randrianarivelojosia, Milijaona; Andagalu, Ben; Maiga-Ascofare, Oumou; Amambua-Ngwa, Alfred; Tindana, Paulina; Ghansah, Anita; MacInnis, Bronwyn; Kwiatkowski, Dominic; Djimde, Abdoulaye A.

2015-01-01

Mutations in the Plasmodium falciparum K13-propeller domain have recently been shown to be important determinants of artemisinin resistance in Southeast Asia. This study investigated the prevalence of K13-propeller polymorphisms across sub-Saharan Africa. A total of 1212 P. falciparum samples collected from 12 countries were sequenced. None of the K13-propeller mutations previously reported in Southeast Asia were found, but 22 unique mutations were detected, of which 7 were nonsynonymous. Allele frequencies ranged between 1% and 3%. Three mutations were observed in >1 country, and the A578S was present in parasites from 5 countries. This study provides the baseline prevalence of K13-propeller mutations in sub-Saharan Africa. PMID:25367300

Clinical, genetic and fertility studies of Indians with beta S-globin gene and the influence of Hb S on Plasmodium falciparum malaria infection.

PubMed

Joishy, S K; Hassan, K; Lopes, M; Lie-Injo, L E

1988-01-01

Clinical studies were carried out on mild Indian sickle cell anaemia in Malaysia, and genetic and fertility studies were carried out on 101 families with and without sickle-cell haemoglobin (Hb S). The Indian sickle cell anaemia patients reached adulthood, and pregnancies and deliveries were uneventful without blood transfusion. There was no foetal wastage and the number of children produced was not significantly different from that in families without Hb S. 28 Indian patients hospitalized with Plasmodium falciparum malaria infection were also examined for their beta S genotype. P. falciparum malaria infection occurred much more frequently in individuals without Hb S than in Hb S carriers.

Selective sweep suggests transcriptional regulation may underlie Plasmodium vivax resilience to malaria control measures in Cambodia

PubMed Central

Parobek, Christian M.; Lin, Jessica T.; Saunders, David L.; Barnett, Eric J.; Lon, Chanthap; Lanteri, Charlotte A.; Balasubramanian, Sujata; Brazeau, Nicholas; DeConti, Derrick K.; Garba, Deen L.; Meshnick, Steven R.; Spring, Michele D.; Chuor, Char Meng; Bailey, Jeffrey A.; Juliano, Jonathan J.

2016-01-01

Cambodia, in which both Plasmodium vivax and Plasmodium falciparum are endemic, has been the focus of numerous malaria-control interventions, resulting in a marked decline in overall malaria incidence. Despite this decline, the number of P. vivax cases has actually increased. To understand better the factors underlying this resilience, we compared the genetic responses of the two species to recent selective pressures. We sequenced and studied the genomes of 70 P. vivax and 80 P. falciparum isolates collected between 2009 and 2013. We found that although P. falciparum has undergone population fracturing, the coendemic P. vivax population has grown undisrupted, resulting in a larger effective population size, no discernable population structure, and frequent multiclonal infections. Signatures of selection suggest recent, species-specific evolutionary differences. Particularly, in contrast to P. falciparum, P. vivax transcription factors, chromatin modifiers, and histone deacetylases have undergone strong directional selection, including a particularly strong selective sweep at an AP2 transcription factor. Together, our findings point to different population-level adaptive mechanisms used by P. vivax and P. falciparum parasites. Although population substructuring in P. falciparum has resulted in clonal outgrowths of resistant parasites, P. vivax may use a nuanced transcriptional regulatory approach to population maintenance, enabling it to preserve a larger, more diverse population better suited to facing selective threats. We conclude that transcriptional control may underlie P. vivax’s resilience to malaria control measures. Novel strategies to target such processes are likely required to eradicate P. vivax and achieve malaria elimination. PMID:27911780

Plasmodium falciparum full life cycle and Plasmodium ovale liver stages in humanized mice.

PubMed

Soulard, Valérie; Bosson-Vanga, Henriette; Lorthiois, Audrey; Roucher, Clémentine; Franetich, Jean-François; Zanghi, Gigliola; Bordessoulles, Mallaury; Tefit, Maurel; Thellier, Marc; Morosan, Serban; Le Naour, Gilles; Capron, Frédérique; Suemizu, Hiroshi; Snounou, Georges; Moreno-Sabater, Alicia; Mazier, Dominique

2015-07-24

Experimental studies of Plasmodium parasites that infect humans are restricted by their host specificity. Humanized mice offer a means to overcome this and further provide the opportunity to observe the parasites in vivo. Here we improve on previous protocols to achieve efficient double engraftment of TK-NOG mice by human primary hepatocytes and red blood cells. Thus, we obtain the complete hepatic development of P. falciparum, the transition to the erythrocytic stages, their subsequent multiplication, and the appearance of mature gametocytes over an extended period of observation. Furthermore, using sporozoites derived from two P. ovale-infected patients, we show that human hepatocytes engrafted in TK-NOG mice sustain maturation of the liver stages, and the presence of late-developing schizonts indicate the eventual activation of quiescent parasites. Thus, TK-NOG mice are highly suited for in vivo observations on the Plasmodium species of humans.

A systematic review: Performance of RDTs for the detection of Plasmodium knowlesi, Plasmodium malariae, and Plasmodium ovale mono-infections in human blood.

PubMed

Yerlikaya, Seda; Campillo, Ana; Gonzalez, Iveth J

2018-03-15

Despite the increased use and worldwide distribution of malaria rapid diagnostic tests (RDTs) which distinguish between Plasmodium falciparum and non-falciparum species, little is known about their performance for detecting Plasmodium knowlesi (Pk), Plasmodium malariae (Pm), and Plasmodium ovale (Po). The objective of this review is to analyze results of published studies evaluating the diagnostic accuracy of malaria RDTs in detecting Pk, Pm and Po mono-infections.MEDLINE, EMBASE, Web of Science and CENTRAL databases were systematically searched to identify studies which reported on the performance of RDTs in detecting Pk, Pm,Po mono-infections.Among 40 studies included in the review, three reported on Pk, eight on Pm, five on Po, one on Pk and Pm, and 23 on Pm and Po infections. In the meta-analysis, estimates of sensitivities of RDTs in detecting Pk infections ranged from 2% to 48%. Test performances for Pm and Po infections were less accurate and highly heterogeneous, mainly due to the small number of samples tested.Limited data available suggest that malaria RDTs show suboptimal performance for detecting Pk, Pm,Po infections. New improved RDTs as well as appropriately designed, cross-sectional studies to demonstrate their usefulness in the detection of neglected Plasmodium species, are urgently needed.

Drug Discovery and Development of Antimalarial Agents: Recent Advances.

PubMed

Thota, Sreekanth; Yerra, Rajeshwar

2016-01-01

Malaria, a deadly infectious parasitic disease, is a major issue of public health in the world today and already produces serious economic constraints in the endemic countries. Most of the malarial infections and deaths are due to Plasmodium falciparum and Plasmodium vivax species. The recent emergence of resistance necessitates the search for new antimalarial drugs, which overcome the resistance and act through new mechanisms. Although much effort has been directed towards the discovery of novel antimalarial drugs. 4-anilino quinolone triazines as potent antimalarial agents, their in silico modelling and bioevaluation as Plasmodium falciparum transketolase and β-hematin inhibitors has been reported. This review is primarily focused on the drug discovery of the recent advances in the development of antimalarial agents and their mechanism of action.

Effect of pharmacogenetics on plasma lumefantrine pharmacokinetics and malaria treatment outcome in pregnant women.

PubMed

Mutagonda, Ritah F; Kamuhabwa, Appolinary A R; Minzi, Omary M S; Massawe, Siriel N; Asghar, Muhammad; Homann, Manijeh V; Färnert, Anna; Aklillu, Eleni

2017-07-03

Pregnancy has considerable effects on the pharmacokinetic properties of drugs used to treat uncomplicated Plasmodium falciparum malaria. The role of pharmacogenetic variation on anti-malarial drug disposition and efficacy during pregnancy is not well investigated. The study aimed to examine the effect of pharmacogenetics on lumefantrine (LF) pharmacokinetics and treatment outcome in pregnant women. Pregnant women with uncomplicated falciparum malaria were enrolled and treated with artemether-lumefantrine (ALu) at Mkuranga and Kisarawe district hospitals in Coast Region of Tanzania. Day-7 LF plasma concentration and genotyping forCYP2B6 (c.516G>T, c.983T>C), CYP3A4*1B, CYP3A5 (*3, *6, *7) and ABCB1 c.4036A4G were determined. Blood smear for parasite quantification by microscopy, and dried blood spot for parasite screening and genotyping using qPCR and nested PCR were collected at enrolment up to day 28 to differentiate between reinfection from recrudescence. Treatment response was recorded following the WHO protocol. In total, 92 pregnant women in their second and third trimester were included in the study and 424 samples were screened for presence of P. falciparum. Parasites were detected during the follow up period in 11 (12%) women between day 7 and 28 after treatment and PCR genotyping confirmed recrudescent infection in 7 (63.3%) women. The remaining four (36.4%) pregnant women had reinfection: one on day 14 and three on day 28. The overall PCR-corrected treatment failure rate was 9.0% (95% CI 4.4-17.4). Day 7 LF concentration was not significantly influenced by CYP2B6, CYP3A4*1B and ABCB1 c.4036A>G genotypes. Significant associations between CYP3A5 genotype and day 7 plasma LF concentrations was found, being higher in carriers of CYP3A5 defective variant alleles than CYP3A5*1/*1 genotype. No significant influence of CYP2B6, CYP3A5 and ABCB1 c.4036A>Genotypes on malaria treatment outcome were observed. However, CYP3A4*1B did affect malaria treatment outcome in pregnant women followed up for 28 days (P = 0.018). Genetic variations in CYP3A4 and CYP3A5may influence LF pharmacokinetics and treatment outcome in pregnant women.

Acyclic phosph(on)ate inhibitors of Plasmodium falciparum hypoxanthine-guanine-xanthine phosphoribosyltransferase

PubMed Central

Clinch, Keith; Crump, Douglas R.; Evans, Gary B.; Hazleton, Keith Z.; Mason, Jennifer M.; Schramm, Vern L.

2013-01-01

The pathogenic protozoa responsible for malaria lack enzymes for the de novo synthesis of purines and rely on purine salvage from the host. In Plasmodium falciparum (Pf), hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) converts hypoxanthine to inosine monophosphate and is essential for purine salvage making the enzyme an anti-malarial drug target. We have synthesized a number of simple acyclic aza-C- nucleosides and shown that some are potent inhibitors of Pf HGXPRT while showing excellent selectivity for the Pf versus the human enzyme. PMID:23810424

Plasmodium falciparum Founder Populations in Western Cambodia Have Reduced Artemisinin Sensitivity In Vitro

PubMed Central

Amaratunga, Chanaki; Witkowski, Benoit; Dek, Dalin; Try, Vorleak; Khim, Nimol; Miotto, Olivo

2014-01-01

Reduced Plasmodium falciparum sensitivity to short-course artemisinin (ART) monotherapy manifests as a long parasite clearance half-life. We recently defined three parasite founder populations with long half-lives in Pursat, western Cambodia, where reduced ART sensitivity is prevalent. Using the ring-stage survival assay, we show that these founder populations have reduced ART sensitivity in vitro at the early ring stage of parasite development and that a genetically admixed population contains subsets of parasites with normal or reduced ART sensitivity. PMID:24867977

The MSPDBL2 Codon 591 Polymorphism Is Associated with Lumefantrine In Vitro Drug Responses in Plasmodium falciparum Isolates from Kilifi, Kenya

PubMed Central

Okombo, John; Mwai, Leah; Kiara, Steven M.; Pole, Lewa; Tetteh, Kevin K. A.; Nzila, Alexis; Marsh, Kevin

2014-01-01

The mechanisms of drug resistance development in the Plasmodium falciparum parasite to lumefantrine (LUM), commonly used in combination with artemisinin, are still unclear. We assessed the polymorphisms of Pfmspdbl2 for associations with LUM activity in a Kenyan population. MSPDBL2 codon 591S was associated with reduced susceptibility to LUM (P = 0.04). The high frequency of Pfmspdbl2 codon 591S in Kenya may be driven by the widespread use of lumefantrine in artemisinin combination therapy (Coartem). PMID:25534732

Antimalarial drug resistance: linking Plasmodium falciparum parasite biology to the clinic

PubMed Central

Blasco, Benjamin; Leroy, Didier; Fidock, David A

2017-01-01

The global adoption of artemisinin-based combination therapies (ACTs) in the early 2000s heralded a new era in effectively treating drug-resistant Plasmodium falciparum malaria. However, several Southeast Asian countries have now reported the emergence of parasites that have decreased susceptibility to artemisinin (ART) derivatives and ACT partner drugs, resulting in increasing rates of treatment failures. Here we review recent advances in understanding how antimalarials act and how resistance develops, and discuss new strategies for effectively combatting resistance, optimizing treatment and advancing the global campaign to eliminate malaria. PMID:28777791

Plasmodium knowlesi malaria during pregnancy.

PubMed

Barber, Bridget E; Bird, Elspeth; Wilkes, Christopher S; William, Timothy; Grigg, Matthew J; Paramaswaran, Uma; Menon, Jayaram; Jelip, Jenarun; Yeo, Tsin W; Anstey, Nicholas M

2015-04-01

Plasmodium knowlesi is the commonest cause of malaria in Malaysia, but little is known regarding infection during pregnancy. To investigate comparative risk and consequences of knowlesi malaria during pregnancy, we reviewed (1) Sabah Health Department malaria-notification records created during 2012-2013, (2) prospectively collected data from all females with polymerase chain reaction (PCR)-confirmed malaria who were admitted to a Sabah tertiary care referral hospital during 2011-2014, and (3) malaria microscopy and clinical data recorded at a Sabah tertiary care women and children's hospital during 2010-2014. During 2012-2013, 774 females with microscopy-diagnosed malaria were notified, including 252 (33%), 172 (20%), 333 (43%), and 17 (2%) with Plasmodium falciparum infection, Plasmodium vivax infection, Plasmodium malariae/Plasmodium knowlesi infection, and mixed infection, respectively. Among females aged 15-45 years, pregnancy was reported in 18 of 124 (14.5%), 9 of 93 (9.7%), and 4 of 151 (2.6%) P. falciparum, P. vivax, and P. malariae/P. knowlesi notifications respectively (P = .002). Three females with knowlesi malaria were confirmed as pregnant: 2 had moderate anemia, and 1 delivered a preterm low-birth-weight infant. There were 17, 7, and 0 pregnant women with falciparum, vivax, and knowlesi malaria, respectively, identified from the 2 referral hospitals. Although P. knowlesi is the commonest malaria species among females in Sabah, P. knowlesi infection is relatively rare during pregnancy. It may however be associated with adverse maternal and pregnancy outcomes. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Combining parasite lactate dehydrogenase-based and histidine-rich protein 2-based rapid tests to improve specificity for diagnosis of malaria Due to Plasmodium knowlesi and other Plasmodium species in Sabah, Malaysia.

PubMed

Grigg, Matthew J; William, Timothy; Barber, Bridget E; Parameswaran, Uma; Bird, Elspeth; Piera, Kim; Aziz, Ammar; Dhanaraj, Prabakaran; Yeo, Tsin W; Anstey, Nicholas M

2014-06-01

Plasmodium knowlesi causes severe and fatal malaria in Malaysia. Microscopic misdiagnosis is common and may delay appropriate treatment. P. knowlesi can cross-react with "species-specific" parasite lactate dehydrogenase (pLDH) monoclonal antibodies used in rapid diagnostic tests (RDTs) to detect P. falciparum and P. vivax. At one tertiary-care hospital and two district hospitals in Sabah, we prospectively evaluated two combination RDTs for malaria diagnosis by using both a pan-Plasmodium-pLDH (pan-pLDH)/P. falciparum-specific-pLDH (Pf-pLDH) RDT (OptiMAL-IT) and a non-P. falciparum VOM-pLDH/Pf-HRP2 RDT (CareStart). Differential cross-reactivity among these combinations was hypothesized to differentiate P. knowlesi from other Plasmodium monoinfections. Among 323 patients with PCR-confirmed P. knowlesi (n = 193), P. falciparum (n = 93), and P. vivax (n = 37) monoinfections, the VOM-pLDH individual component had the highest sensitivity for nonsevere (35%; 95% confidence interval [CI], 27 to 43%) and severe (92%; CI, 81 to 100%) P. knowlesi malaria. CareStart demonstrated a P. knowlesi sensitivity of 42% (CI, 34 to 49%) and specificity of 74% (CI, 65 to 82%), a P. vivax sensitivity of 83% (CI, 66 to 93%) and specificity of 71% (CI, 65 to 76%), and a P. falciparum sensitivity of 97% (CI, 90 to 99%) and specificity of 99% (CI, 97 to 100%). OptiMAL-IT demonstrated a P. knowlesi sensitivity of 32% (CI, 25 to 39%) and specificity of 21% (CI, 15 to 29%), a P. vivax sensitivity of 60% (CI, 42 to 75%) and specificity of 97% (CI, 94 to 99%), and a P. falciparum sensitivity of 82% (CI, 72 to 89%) and specificity of 39% (CI, 33 to 46%). The combination of CareStart plus OptiMAL-IT for P. knowlesi using predefined criteria gave a sensitivity of 25% (CI, 19 to 32%) and specificity of 97% (CI, 92 to 99%). Combining two RDT combinations was highly specific for P. knowlesi malaria diagnosis; however, sensitivity was poor. The specificity of pLDH RDTs was decreased for P. vivax and P. falciparum because of P. knowlesi cross-reactivity and cautions against their use alone in areas where P. knowlesi malaria is endemic. Sensitive P. knowlesi-specific RDTs and/or alternative molecular diagnostic tools are needed in areas where P. knowlesi malaria is endemic. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Combining Parasite Lactate Dehydrogenase-Based and Histidine-Rich Protein 2-Based Rapid Tests To Improve Specificity for Diagnosis of Malaria Due to Plasmodium knowlesi and Other Plasmodium Species in Sabah, Malaysia

PubMed Central

William, Timothy; Barber, Bridget E.; Parameswaran, Uma; Bird, Elspeth; Piera, Kim; Aziz, Ammar; Dhanaraj, Prabakaran; Yeo, Tsin W.; Anstey, Nicholas M.

2014-01-01

Plasmodium knowlesi causes severe and fatal malaria in Malaysia. Microscopic misdiagnosis is common and may delay appropriate treatment. P. knowlesi can cross-react with “species-specific” parasite lactate dehydrogenase (pLDH) monoclonal antibodies used in rapid diagnostic tests (RDTs) to detect P. falciparum and P. vivax. At one tertiary-care hospital and two district hospitals in Sabah, we prospectively evaluated two combination RDTs for malaria diagnosis by using both a pan-Plasmodium-pLDH (pan-pLDH)/P. falciparum-specific-pLDH (Pf-pLDH) RDT (OptiMAL-IT) and a non-P. falciparum VOM-pLDH/Pf-HRP2 RDT (CareStart). Differential cross-reactivity among these combinations was hypothesized to differentiate P. knowlesi from other Plasmodium monoinfections. Among 323 patients with PCR-confirmed P. knowlesi (n = 193), P. falciparum (n = 93), and P. vivax (n = 37) monoinfections, the VOM-pLDH individual component had the highest sensitivity for nonsevere (35%; 95% confidence interval [CI], 27 to 43%) and severe (92%; CI, 81 to 100%) P. knowlesi malaria. CareStart demonstrated a P. knowlesi sensitivity of 42% (CI, 34 to 49%) and specificity of 74% (CI, 65 to 82%), a P. vivax sensitivity of 83% (CI, 66 to 93%) and specificity of 71% (CI, 65 to 76%), and a P. falciparum sensitivity of 97% (CI, 90 to 99%) and specificity of 99% (CI, 97 to 100%). OptiMAL-IT demonstrated a P. knowlesi sensitivity of 32% (CI, 25 to 39%) and specificity of 21% (CI, 15 to 29%), a P. vivax sensitivity of 60% (CI, 42 to 75%) and specificity of 97% (CI, 94 to 99%), and a P. falciparum sensitivity of 82% (CI, 72 to 89%) and specificity of 39% (CI, 33 to 46%). The combination of CareStart plus OptiMAL-IT for P. knowlesi using predefined criteria gave a sensitivity of 25% (CI, 19 to 32%) and specificity of 97% (CI, 92 to 99%). Combining two RDT combinations was highly specific for P. knowlesi malaria diagnosis; however, sensitivity was poor. The specificity of pLDH RDTs was decreased for P. vivax and P. falciparum because of P. knowlesi cross-reactivity and cautions against their use alone in areas where P. knowlesi malaria is endemic. Sensitive P. knowlesi-specific RDTs and/or alternative molecular diagnostic tools are needed in areas where P. knowlesi malaria is endemic. PMID:24696029

Proteogenomic analysis of the total and surface-exposed proteomes of Plasmodium vivax salivary gland sporozoites

PubMed Central

Swearingen, Kristian E.; Lindner, Scott E.; Flannery, Erika L.; Vaughan, Ashley M.; Morrison, Robert D.; Patrapuvich, Rapatbhorn; Koepfli, Cristian; Muller, Ivo; Jex, Aaron; Moritz, Robert L.; Kappe, Stefan H. I.; Sattabongkot, Jetsumon

2017-01-01

Plasmodium falciparum and Plasmodium vivax cause the majority of human malaria cases. Research efforts predominantly focus on P. falciparum because of the clinical severity of infection and associated mortality rates. However, P. vivax malaria affects more people in a wider global range. Furthermore, unlike P. falciparum, P. vivax can persist in the liver as dormant hypnozoites that can be activated weeks to years after primary infection, causing relapse of symptomatic blood stages. This feature makes P. vivax unique and difficult to eliminate with the standard tools of vector control and treatment of symptomatic blood stage infection with antimalarial drugs. Infection by Plasmodium is initiated by the mosquito-transmitted sporozoite stage, a highly motile invasive cell that targets hepatocytes in the liver. The most advanced malaria vaccine for P. falciparum (RTS,S, a subunit vaccine containing of a portion of the major sporozoite surface protein) conferred limited protection in Phase III trials, falling short of WHO-established vaccine efficacy goals. However, blocking the sporozoite stage of infection in P. vivax, before the establishment of the chronic liver infection, might be an effective malaria vaccine strategy to reduce the occurrence of relapsing blood stages. It is also thought that a multivalent vaccine comprising multiple sporozoite surface antigens will provide better protection, but a comprehensive analysis of proteins in P. vivax sporozoites is not available. To inform sporozoite-based vaccine development, we employed mass spectrometry-based proteomics to identify nearly 2,000 proteins present in P. vivax salivary gland sporozoites. Analysis of protein post-translational modifications revealed extensive phosphorylation of glideosome proteins as well as regulators of transcription and translation. Additionally, the sporozoite surface proteins CSP and TRAP, which were recently discovered to be glycosylated in P. falciparum salivary gland sporozoites, were also observed to be similarly modified in P. vivax sporozoites. Quantitative comparison of the P. vivax and P. falciparum salivary gland sporozoite proteomes revealed a high degree of similarity in protein expression levels, including among invasion-related proteins. Nevertheless, orthologs with significantly different expression levels between the two species could be identified, as well as highly abundant, species-specific proteins with no known orthologs. Finally, we employed chemical labeling of live sporozoites to isolate and identify 36 proteins that are putatively surface-exposed on P. vivax salivary gland sporozoites. In addition to identifying conserved sporozoite surface proteins identified by similar analyses of other Plasmodium species, our analysis identified several as-yet uncharacterized proteins, including a putative 6-Cys protein with no known ortholog in P. falciparum. PMID:28759593

Assessment of pfcrt 72-76 haplotypes eight years after chloroquine withdrawal in Kinshasa, Democratic Republic of Congo.

PubMed

Mvumbi, Dieudonné Makaba; Boreux, Raphael; Sacheli, Rosalie; Lelo, Mvumbi; Lengu, Bobanga; Nani-Tuma, Situakibanza; Melin, Pierrette; Ntumba, Kayembe; Lunganza, Kalala; DeMol, Patrick; Hayette, Marie-Pierre

2013-12-20

In 2001, the World Health Organization (WHO) has recommended the use of artemisinin-based combination therapy (ACT) as the first-line treatment of uncomplicated malaria cases, as monotherapies had become ineffective in many parts of the world. As a result, the Democratic Republic of Congo (DRC) withdrew chloroquine (CQ) from its malaria treatment policy in 2002 and an artesunate (AS)-amodiaquine (AQ) combination became the ACT of choice in DRC in 2005. AQ-resistance (AQR) has been reported in several parts of the world and mutations in codons 72-76 of the Plasmodium falciparum chloroquine-resistance transporter (pfcrt) gene have been strongly correlated with resistance, especially mutations encoding the SVMNT haplotype. This haplotype was first identified in Southeast Asia and South America but was recently reported in two African countries neighbouring DRC. These facts raised two questions: the first about the evolution of CQ resistance (CQR) in DRC and the second about the presence of the SVMNT haplotype, which would compromise the use of AQ as a partner drug for ACT. A total of 213 thick blood films were randomly collected in 2010 from a paediatric clinic in Kinshasa, DRC. Microscopy controls and real-time polymerase chain reaction (RT-PCR) were performed for Plasmodium species identification. Haplotypes of the pfcrt gene were determined by sequencing. The K76T mutation was detected in 145 out of 198 P. falciparum-positive samples (73.2%). In these 145 resistant strains, only the CVIET haplotype was detected. This study is the first to assess the molecular markers of resistance to CQ and AQ after the introduction of ACT in DRC. The results suggest first that CQR is decreasing, as wild-type pfcrt haplotypes were found in only 26.8% of the samples and secondly that the SVMNT haplotype is not yet present in Kinshasa, suggesting that AQ remains valid as a partner drug for ACT in this region.

Malaria burden and anti-malarial drug efficacy in Owando, northern Congo.

PubMed

Singana, Brice P; Bogreau, Hervé; Matondo, Brunelle D; Dossou-Yovo, Louis R; Casimiro, Prisca N; Mbouka, Rigobert; Ha Nguyen, Kim Yen; Pradines, Bruno; Basco, Leonardo K; Ndounga, Mathieu

2016-01-08

In the Republic of Congo, previous epidemiological studies have only been conducted in the south of the country where it is most accessible. Nationally representative data on the efficacy of new anti-malarial tools are lacking in the country. As an initial step to close the gap, clinical efficacy of two artemisinin-based combinations, artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL), was assessed in Owando, a city in equatorial flooded forest in northern Republic of Congo. Under 12 years old febrile children attending public health facilities were screened for malaria parasites using lactate dehydrogenase (LDH)-based rapid diagnostic test (RDT) for malaria and microscopic examination of thick blood films. Patients with at least 1,000 asexual Plasmodium falciparum parasites/µl of blood were clinically examined, included after informed consent, and followed up for 28 days, according to the 2009 World Health Organization protocol. Patients were randomly assigned to co-formulated ASAQ (Coarsucam(®)) or AL (Coartem(®)) treatment groups. Plasmodium falciparum recrudescent isolates were compared to pre-treatment isolates by polymerase chain reaction (PCR) using msp1, msp2, and glurp genes to distinguish between re-infection and recrudescence. Between November 2012 and February 2013, 857 under 12 years old febrile children were screened, of whom 198 (23.1%) had positive RDT and 167 (19.5%) positive thick films. ASAQ and AL efficacies were 92.7 and 94.2% before PCR correction, respectively. After genotyping, the overall efficacy was 100% for ASAQ and 98.0% for AL. The data reported here represent partially the burden of malaria in 0-11 years old febrile children examined in public health centres of Owando city and serve as reference for further studies. Both artemisinin-based combinations were highly efficacious in patients under 12 years old with acute uncomplicated malaria. ASAQ was associated with more adverse events, which may reduce compliance in unsupervised treatment. ACTRN12612000940875.

Declining Efficacy of Artemisinin Combination Therapy Against P. Falciparum Malaria on the Thai-Myanmar Border (2003-2013): The Role of Parasite Genetic Factors.

PubMed

Phyo, Aung Pyae; Ashley, Elizabeth A; Anderson, Tim J C; Bozdech, Zbynek; Carrara, Verena I; Sriprawat, Kanlaya; Nair, Shalini; White, Marina McDew; Dziekan, Jerzy; Ling, Clare; Proux, Stephane; Konghahong, Kamonchanok; Jeeyapant, Atthanee; Woodrow, Charles J; Imwong, Mallika; McGready, Rose; Lwin, Khin Maung; Day, Nicholas P J; White, Nicholas J; Nosten, Francois

2016-09-15

Deployment of mefloquine-artesunate (MAS3) on the Thailand-Myanmar border has led to a sustained reduction in falciparum malaria, although antimalarial efficacy has declined substantially in recent years. The role of Plasmodium falciparum K13 mutations (a marker of artemisinin resistance) in reducing treatment efficacy remains controversial. Between 2003 and 2013, we studied the efficacy of MAS3 in 1005 patients with uncomplicated P. falciparum malaria in relation to molecular markers of resistance. Polymerase chain reaction (PCR)-adjusted cure rates declined from 100% in 2003 to 81.1% in 2013 as the proportions of isolates with multiple Pfmdr1 copies doubled from 32.4% to 64.7% and those with K13 mutations increased from 6.7% to 83.4%. K13 mutations conferring moderate artemisinin resistance (notably E252Q) predominated initially but were later overtaken by propeller mutations associated with slower parasite clearance (notably C580Y). Those infected with both multiple Pfmdr1 copy number and a K13 propeller mutation were 14 times more likely to fail treatment. The PCR-adjusted cure rate was 57.8% (95% confidence interval [CI], 45.4, 68.3) compared with 97.8% (95% CI, 93.3, 99.3) in patients with K13 wild type and Pfmdr1 single copy. K13 propeller mutation alone was a strong risk factor for recrudescence (P = .009). The combined population attributable fraction of recrudescence associated with K13 mutation and Pfmdr1 amplification was 82%. The increasing prevalence of K13 mutations was the decisive factor for the recent and rapid decline in efficacy of artemisinin-based combination (MAS3) on the Thailand-Myanmar border. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America.

Evolution of Fseg/Cseg dimorphism in region III of the Plasmodium falciparum eba-175 gene.

PubMed

Yasukochi, Yoshiki; Naka, Izumi; Patarapotikul, Jintana; Hananantachai, Hathairad; Ohashi, Jun

2017-04-01

The 175-kDa erythrocyte binding antigen (EBA-175) of the malaria parasite Plasmodium falciparum is important for its invasion into human erythrocytes. The primary structure of eba-175 is divided into seven regions, namely I to VII. Region III contains highly divergent dimorphic segments, termed Fseg and Cseg. The allele frequencies of segmental dimorphism within a P. falciparum population have been extensively examined; however, the molecular evolution of segmental dimorphism is not well understood. A comprehensive comparison of nucleotide sequences among 32 P. falciparum eba-175 alleles identified in our previous study, two Plasmodium reichenowi, and one P. gaboni orthologous alleles obtained from the GenBank database was conducted to uncover the origin and evolutionary processes of segmental dimorphism in P. falciparum eba-175. In the eba-175 nucleotide sequence derived from a P. reichenowi CDC strain, both Fseg and Cseg were found in region III, which implies that the original eba-175 gene had both segments, and deletions of F- and C-segments generated Cseg and Fseg alleles, respectively. We also confirmed the presence of allele with Fseg and Cseg in another P. reichenowi strain (SY57), by re-mapping short reads obtained from the GenBank database. On the other hand, the segmental sequence of eba-175 ortholog in P. gaboni was quite diverged from those of the other species, suggesting that the original eba-175 dimorphism of P. falciparum can be traced back to the stem linage of P. falciparum and P. reichenowi. Our findings suggest that Fseg and Cseg alleles are derived from a single eba-175 allele containing both segments in the ancestral population of P. falciparum and P. reichenowi, and that the allelic dimorphism of eba-175 was shaped by the independent emergence of similar dimorphic lineage in different species that has never been observed in any evolutionary mode of allelic dimorphism at other loci in malaria genomes. Copyright © 2017 Elsevier B.V. All rights reserved.

Plasmodium falciparum Malaria Endemicity in Indonesia in 2010

PubMed Central

Elyazar, Iqbal R. F.; Gething, Peter W.; Patil, Anand P.; Rogayah, Hanifah; Kusriastuti, Rita; Wismarini, Desak M.; Tarmizi, Siti N.; Baird, J. Kevin; Hay, Simon I.

2011-01-01

Background Malaria control programs require a detailed understanding of the contemporary spatial distribution of infection risk to efficiently allocate resources. We used model based geostatistics (MBG) techniques to generate a contemporary map of Plasmodium falciparum malaria risk in Indonesia in 2010. Methods Plasmodium falciparum Annual Parasite Incidence (PfAPI) data (2006–2008) were used to map limits of P. falciparum transmission. A total of 2,581 community blood surveys of P. falciparum parasite rate (PfPR) were identified (1985–2009). After quality control, 2,516 were included into a national database of age-standardized 2–10 year old PfPR data (PfPR2–10) for endemicity mapping. A Bayesian MBG procedure was used to create a predicted surface of PfPR2–10 endemicity with uncertainty estimates. Population at risk estimates were derived with reference to a 2010 human population count surface. Results We estimate 132.8 million people in Indonesia, lived at risk of P. falciparum transmission in 2010. Of these, 70.3% inhabited areas of unstable transmission and 29.7% in stable transmission. Among those exposed to stable risk, the vast majority were at low risk (93.39%) with the reminder at intermediate (6.6%) and high risk (0.01%). More people in western Indonesia lived in unstable rather than stable transmission zones. In contrast, fewer people in eastern Indonesia lived in unstable versus stable transmission areas. Conclusion While further feasibility assessments will be required, the immediate prospects for sustained control are good across much of the archipelago and medium term plans to transition to the pre-elimination phase are not unrealistic for P. falciparum. Endemicity in areas of Papua will clearly present the greatest challenge. This P. falciparum endemicity map allows malaria control agencies and their partners to comprehensively assess the region-specific prospects for reaching pre-elimination, monitor and evaluate the effectiveness of future strategies against this 2010 baseline and ultimately improve their evidence-based malaria control strategies. PMID:21738634

Cost–effectiveness of artemisinin combination therapy for uncomplicated malaria in children: data from Papua New Guinea

PubMed Central

Davis, Wendy A; Clarke, Philip M; Siba, Peter M; Karunajeewa, Harin A; Davy, Carol; Mueller, Ivo

2011-01-01

Abstract Objective To compare the cost–effectiveness of conventional antimalarial therapy with that of three artemisinin combination treatment regimens in children from Papua New Guinea aged 6 to 60 months. Methods An incremental cost–effectiveness analysis was performed using data from 656 children with Plasmodium falciparum and/or P. vivax malaria who participated in a large intervention trial in two clinics in northern Papua New Guinea. The children were randomized to one of the following groups: (i) conventional treatment with chloroquine plus sulfadoxine plus pyrimethamine (CQ+S+P); (ii) artesunate plus S plus P; (iii) dihydroartemisinin plus piperaquine (DHA+PQ); and (iv) artemether plus lumefantrine (A+L). For treatment outcomes, World Health Organization definitions were used. The cost of transport between home and the clinic plus direct health-care costs served as a basis for determining each regimen’s incremental cost per incremental treatment success relative to CQ+S+P by day 42 and its cost per life year saved. Findings A+L proved to be the most effective regimen against P. falciparum malaria and was highly cost-effective at 6.97 United States dollars (US$) per treatment success (about US$ 58 per life year saved). DHA+PQ was the most effective regimen against P. vivax malaria and was more cost-effective than CQ+S+P. Conclusion A+L and DHA+PQ are highly cost-effective regimens for the treatment of paediatric P. falciparum and P. vivax malaria, respectively, in parts of Papua New Guinea. Future research will be required to determine if these findings hold true for other territories in Asia and Oceania with similar malaria epidemiology. PMID:21379417

Declining responsiveness of Plasmodium falciparum infections to artemisinin-based combination treatments on the Kenyan coast.

PubMed

Borrmann, Steffen; Sasi, Philip; Mwai, Leah; Bashraheil, Mahfudh; Abdallah, Ahmed; Muriithi, Steven; Frühauf, Henrike; Schaub, Barbara; Pfeil, Johannes; Peshu, Judy; Hanpithakpong, Warunee; Rippert, Anja; Juma, Elizabeth; Tsofa, Benjamin; Mosobo, Moses; Lowe, Brett; Osier, Faith; Fegan, Greg; Lindegårdh, Niklas; Nzila, Alexis; Peshu, Norbert; Mackinnon, Margaret; Marsh, Kevin

2011-01-01

The emergence of artemisinin-resistant P. falciparum malaria in South-East Asia highlights the need for continued global surveillance of the efficacy of artemisinin-based combination therapies. On the Kenyan coast we studied the treatment responses in 474 children 6-59 months old with uncomplicated P. falciparum malaria in a randomized controlled trial of dihydroartemisinin-piperaquine vs. artemether-lumefantrine from 2005 to 2008. (ISRCTN88705995). The proportion of patients with residual parasitemia on day 1 rose from 55% in 2005-2006 to 87% in 2007-2008 (odds ratio, 5.4, 95%CI, 2.7-11.1; P<0.001) and from 81% to 95% (OR, 4.1, 95%CI, 1.7-9.9; P = 0.002) in the DHA-PPQ and AM-LM groups, respectively. In parallel, Kaplan-Meier estimated risks of apparent recrudescent infection by day 84 increased from 7% to 14% (P = 0.1) and from 6% to 15% (P = 0.05) with DHA-PPQ and AM-LM, respectively. Coinciding with decreasing transmission in the study area, clinical tolerance to parasitemia (defined as absence of fever) declined between 2005-2006 and 2007-2008 (OR body temperature >37.5°C, 2.8, 1.9-4.1; P<0.001). Neither in vitro sensitivity of parasites to DHA nor levels of antibodies against parasite extract accounted for parasite clearance rates or changes thereof. The significant, albeit small, decline through time of parasitological response rates to treatment with ACTs may be due to the emergence of parasites with reduced drug sensitivity, to the coincident reduction in population-level clinical immunity, or both. Maintaining the efficacy of artemisinin-based therapy in Africa would benefit from a better understanding of the mechanisms underlying reduced parasite clearance rates. Controlled-Trials.com ISRCTN88705995.

Drug Evaluation in the Plasmodium Falciparum - Aotus Model

DTIC Science & Technology

1994-03-15

falciparum infections. Althogh erythromycin is inactive against chloroquine -resistant falciparum infections, an analogue , azithromycin, is effective in vitro...response to chloroquine , and then expand the evaluation of WR 238605, a primaquine analogue against infections. Each cyopreserved sample was thawed rapidly...confirmedo.4 chloroquine -sensitive p. via -strai-n[as not Infective for unaltered Panamanian Aotus. 14. SUBJECT TERMS 15. NUMBER OF PAGES Malaria

New insights into host-parasite ubiquitin proteome dynamics in P. falciparum infected red blood cells using a TUBEs-MS approach.

PubMed

Mata-Cantero, Lydia; Azkargorta, Mikel; Aillet, Fabienne; Xolalpa, Wendy; LaFuente, Maria J; Elortza, Felix; Carvalho, Ana Sofia; Martin-Plaza, Julio; Matthiesen, Rune; Rodriguez, Manuel S

2016-04-29

Malaria, caused by Plasmodium falciparum (P. falciparum), ranks as one of the most baleful infectious diseases worldwide. New antimalarial treatments are needed to face existing or emerging drug resistant strains. Protein degradation appears to play a significant role during the asexual intraerythrocytic developmental cycle (IDC) of P. falciparum. Inhibition of the ubiquitin proteasome system (UPS), a major intracellular proteolytic pathway, effectively reduces infection and parasite replication. P. falciparum and erythrocyte UPS coexist during IDC but the nature of their relationship is largely unknown. We used an approach based on Tandem Ubiquitin-Binding Entities (TUBEs) and 1D gel electrophoresis followed by mass spectrometry to identify major components of the TUBEs-associated ubiquitin proteome of both host and parasite during ring, trophozoite and schizont stages. Ring-exported protein (REX1), a P. falciparum protein located in Maurer's clefts and important for parasite nutrient import, was found to reach a maximum level of ubiquitylation in trophozoites stage. The Homo sapiens (H. sapiens) TUBEs associated ubiquitin proteome decreased during the infection, whereas the equivalent P. falciparum TUBEs-associated ubiquitin proteome counterpart increased. Major cellular processes such as DNA repair, replication, stress response, vesicular transport and catabolic events appear to be regulated by ubiquitylation along the IDC P. falciparum infection. In this work we analyze for the first time the interconnection between Plasmodium and human red blood cells ubiquitin-regulated proteins in the context of infection. We identified a number of human and Plasmodium proteins whose ubiquitylation pattern changes during the asexual infective stage. We demonstrate that ubiquitylation of REX1, a P. falciparum protein located in Maurer's clefts and important for parasite nutrient import, peaks in trophozoites stage. The ubiquitin-proteome from P. falciparum infected red blood cells (iRBCs) revealed a significant host-parasite crosstalk, underlining the importance of ubiquitin-regulated proteolytic activities during the intraerythrocytic developmental cycle (IDC) of P. falciparum. Major cellular processes defined from gene ontology such as DNA repair, replication, stress response, vesicular transport and catabolic events appear to be regulated by ubiquitylation along the IDC P. falciparum infection. Given the importance of ubiquitylation in the development of infectious diseases, this work provides a number of potential drug-target candidates that should be further explored. Copyright © 2016 Elsevier B.V. All rights reserved.

Antimalarial drug susceptibility and point mutations associated with drug resistance in 248 Plasmodium falciparum isolates imported from Comoros to Marseille, France in 2004 2006.

PubMed

Parola, Philippe; Pradines, Bruno; Simon, Fabrice; Carlotti, Marie-Paule; Minodier, Philippe; Ranjeva, Marie-Pierre; Badiaga, Sékéné; Bertaux, Lionel; Delmont, Jean; Morillon, Marc; Silai, Ramatou; Brouqui, Philippe; Parzy, Daniel

2007-09-01

A total of 248 Plasmodium falciparum isolates were sampled in travelers with malaria who came to Marseille, France from Comoros to investigate in vitro activities of antimalarial drugs and molecular markers of drug resistance. Of the 248 isolates, 126 were maintained in culture. Of these, 53% were resistant to chloroquine, and 3% had reduced susceptibility to quinine, mefloquine, and atovaquone; 1% had reduced susceptibility to halofantrine and dihydroartemisinin; 7% had reduced susceptibility to monodesethylamodiaquine; 37% had reduced susceptibility to cycloguanil; and none had reduced susceptibility to lumefantrine. Resistance-associated point mutations were screened in 207 isolates. No mutations in the cytochrome b gene were found. Of the 207 isolates, 119 (58%) had a mutation in the P. falciparum dihydrofolate reductase (Pfdhfr) gene at codon 108, 6 (5%) had mutations in both Pfdhfr codon 108 and the P. falciparum dihydropteroate synthase codon 437, and 115 (56%) had the chloroquine resistance-associated K76T mutation in the P. falciparum chloroquine resistance transporter gene. This study represents a unique opportunity to improve surveillance of P. falciparum drug resistance in Comoros with consequences for treatment and chemoprophylaxis guidelines.

[Detection of Plasmodium falciparum by using magnetic nanoparticles separation-based quantitative real-time PCR assay].

PubMed

Wang, Fei; Tian, Yin; Yang, Jing; Sun, Fu-Jun; Sun, Ning; Liu, Bi-Yong; Tian, Rui; Ge, Guang-Lu; Zou, Ming-qiang; Deng, Cong-liang; Liu, Yi

2014-10-01

To establish a magnetic nanoparticles separation-based quantitative real-time PCR (RT-PCR) assay for fast and accurate detection of Plasmodium falciparum and providing a technical support for improving the control and prevention of imported malaria. According to the conserved sequences of the P. falciparum genome 18SrRNA, the species-specific primers and probe were designed and synthetized. The RT-PCR was established by constructing the plasmid standard, fitting the standard curve and using magnetic nanoparticles separation. The sensitivity and specificity of the assay were evaluated. The relationship between the threshold cycle (Ct) and logarithm of initial templates copies was linear over a range of 2.5 x 10(1) to 2.5 x 10(8) copies/μl (R2 = 0.999). Among 13 subjects of entry frontier, a P. falciparum carrier with low load was detected by using the assay and none was detected with the conventional examinations (microscopic examinations and rapid tests). This assay shows a high sensitivity in detection of P. falciparum, with rapid and accurate characteristics, and is especially useful in diagnosis of P. falciparum infectors with low parasitaemia at entry-exit frontier ports.

An investigation of the protective effect of alpha+-thalassaemia against severe Plasmodium falciparum amongst children in Kumasi, Ghana.

PubMed

Opoku-Okrah, C; Gordge, M; Kweku Nakua, E; Abgenyega, T; Parry, M; Robertson, C; Smith, C L

2014-02-01

Several factors influence the severity of Plasmodium falciparum; here, we investigate the impact of alpha+-thalassaemia genotype on P. falciparum parasitemia and prevalence of severe anaemia amongst microcytic children from Kumasi, Ghana. Seven hundred and thirty-two children (≤10 years) with P. falciparum were categorised into normocytic and microcytic (mean cell volume ≤76 fL). Microcytic individuals were genotyped for the -α(3.7) deletional thalassaemia mutation and parasite densities determined. Amongst microcytic patients both parasite densities and prevalence of severe malaria parasitemia (≥100 000/μL) were significantly lower (P < 0.001) in the presence of an alpha+-thalassaemia genotype compared with non-alpha+-thalassaemia genotype. There was no evidence that alpha+-thalassaemia protected against severe anaemia. The protection conferred by alpha-thalassaemia genotype against severe P. falciparum parasitemia did not change with increasing age. The severity of P. falciparum parasitemia was significantly lower in both the homozygous and heterozygous alpha+-thalassaemia groups compared with microcytic individuals with non-alpha+-thalassaemia genotype. The protective effect, from severe malaria, of the alpha+-thalassaemia allele does not alter with age. © 2013 John Wiley & Sons Ltd.

The Origin of Malignant Malaria

USDA-ARS?s Scientific Manuscript database

Plasmodium falciparum is the causative agent of malignant malaria, which is among the most severe human infectious diseases. Despite its overwhelming significance to human health, the parasite’s origins remain unclear. The favored origin hypothesis holds that P. falciparum and its closest known rel...

Genome-Level Determination of Plasmodium falciparum Blood-Stage Targets of Malarial Clinical Immunity in the Peruvian Amazon

PubMed Central

Torres, Katherine J.; Castrillon, Carlos E.; Moss, Eli L.; Saito, Mayuko; Tenorio, Roy; Molina, Douglas M.; Davies, Huw; Neafsey, Daniel E.; Felgner, Philip; Vinetz, Joseph M.; Gamboa, Dionicia

2015-01-01

Background. Persons with blood-stage Plasmodium falciparum parasitemia in the absence of symptoms are considered to be clinically immune. We hypothesized that asymptomatic subjects with P. falciparum parasitemia would differentially recognize a subset of P. falciparum proteins on a genomic scale. Methods and Findings. Compared with symptomatic subjects, sera from clinically immune, asymptomatically infected individuals differentially recognized 51 P. falciparum proteins, including the established vaccine candidate PfMSP1. Novel, hitherto unstudied hypothetical proteins and other proteins not previously recognized as potential vaccine candidates were also differentially recognized. Genes encoding the proteins differentially recognized by the Peruvian clinically immune individuals exhibited a significant enrichment of nonsynonymous nucleotide variation, an observation consistent with these genes undergoing immune selection. Conclusions. A limited set of P. falciparum protein antigens was associated with the development of naturally acquired clinical immunity in the low-transmission setting of the Peruvian Amazon. These results imply that, even in a low-transmission setting, an asexual blood-stage vaccine designed to reduce clinical malaria symptoms will likely need to contain large numbers of often-polymorphic proteins, a finding at odds with many current efforts in the design of vaccines against asexual blood-stage P. falciparum. PMID:25381370

Functional characterization and comparison of Plasmodium falciparum proteins as targets of transmission-blocking antibodies.

PubMed

Nikolaeva, Daria; Illingworth, Joseph J; Miura, Kazutoyo; Alanine, Daniel Gw; Brian, Iona J; Li, Yuanyuan; Fyfe, Alex J; Da, Dari F; Cohuet, Anna; Long, Carole A; Draper, Simon J; Biswas, Sumi

2017-10-31

Plasmodium falciparum malaria continues to evade control efforts, utilizing highly specialized sexual-stages to transmit infection between the human host and mosquito vector. In a vaccination model, antibodies directed to sexual-stage antigens, when ingested in the mosquito blood meal, can inhibit parasite growth in the midgut and consequently arrest transmission. Despite multiple datasets for the Plasmodium sexual-stage transcriptome and proteome, there have been no rational screens to identify candidate antigens for transmission-blocking vaccine (TBV) development. This study characterizes 12 proteins from across the P. falciparum sexual-stages as possible TBV targets. Recombinant proteins are heterologously expressed as full-length ectodomains in a mammalian HEK293 cell system. The proteins recapitulate native parasite epitopes as assessed by indirect fluorescence assay and a proportion exhibits immunoreactivity when tested against sera from individuals living in malaria-endemic Burkina Faso and Mali. Purified IgG generated to the mosquito-stage parasite antigen enolase demonstrates moderate inhibition of parasite development in the mosquito midgut by the ex vivo standard membrane feeding assay. The findings support the use of rational screens and comparative functional assessments in identifying proteins of the P. falciparum transmission pathway and establishing a robust pre-clinical TBV pipeline. Copyright © 2017, The American Society for Biochemistry and Molecular Biology.

Detection of the Plasmodium falciparum Kelch-13 gene P553L mutation in sporozoites isolated from mosquito salivary glands in South-Central Vietnam.

PubMed

Maeno, Yoshimasa; Quang, Nguyen Tuyen; Culleton, Richard; Kawai, Satoru; Masuda, Gaku; Hori, Kaoru; Nakazawa, Shusuke; Marchand, Ron P

2017-06-24

Plasmodium falciparum has developed resistance against artemisinin in Southeast Asia. Mutations in the P. falciparum Kelch-13 (Pfk13) gene are associated with artemisinin resistance in vitro and in vivo. We investigated the prevalence of mutations in PfK13 from sporozoite-stage parasites isolated from the salivary glands of Anopheles dirus mosquitoes. Mosquitoes were caught by human-landing catches at two locations within the Khanh Phu commune, South-Central Vietnam. Identification of Anopheles species was performed based on morphological features and nucleotide sequence analysis. Sporozoite-infected salivary glands were stored on filter paper and at 4-6 °C. A nested-PCR targeting the small subunit ribosomal RNA gene was used for Plasmodium species identification. Pfk13 was amplified by nested PCR, and subjected to nucleotide sequencing. Five of 33 P. falciparum sporozoite samples carried the P553L mutation at the PfK13 locus. This mutation has been recorded previously in Vietnam, but not in Khanh Hoa province, were surveys of K13 polymorphism have not previously been carried out. These results demonstrate the utility of mosquito-stage malaria parasite samples for studies on the molecular epidemiology of drug resistance.

Response of falciparum malaria to different antimalarials in Myanmar.

PubMed Central

Ejov, M. N.; Tun, T.; Aung, S.; Sein, K.

1999-01-01

The purpose of the study was to ascertain the therapeutic efficacy of different treatments for uncomplicated falciparum malaria in the hospitals in Sagaing, northern and eastern Shan, to facilitate updating the existing national antimalarial drug policy. The proposed 14-day trial for monitoring the efficacy of treatments of uncomplicated falciparum malaria is an efficient method for identifying treatment failure patterns at the intermediate level (township hospital) in the Union of Myanmar. Minimal clinical and parasitological data for days 0-14 were required to classify treatment failure and success. Clinical and parasitiological responses on day 3 and days 4-14 were used as clear examples of early and late treatment failure, respectively. Mefloquine is five times more likely to be effective than chloroquine and sulfadoxine pyrimethamine (S-P), whereas chloroquine and S-P treatments have nearly identical failure patterns. The alarming frequency of clinical and parasitological failure (failure rate > 50%) following chloroquine treatment was reported in Sagaing and following S-P treatment in Sagaing and eastern Shan. PMID:10212515

MOLECULAR SURVEILLANCE OF Plasmodium vivax AND Plasmodium falciparum DHFR MUTATIONS IN ISOLATES FROM SOUTHERN IRAN

PubMed Central

SHARIFI-SARASIABI, Khojasteh; HAGHIGHI, Ali; KAZEMI, Bahram; TAGHIPOUR, Niloofar; MOJARAD, Ehsan Nazemalhosseini; GACHKAR, Latif

2016-01-01

In Iran, both Plasmodium vivax and P. falciparum malaria have been detected, but P. vivax is the predominant species. Point mutations in dihydrofolate reductase (dhfr) gene in both Plasmodia are the major mechanisms of pyrimethamine resistance. From April 2007 to June 2009, a total of 134 blood samples in two endemic areas of southern Iran were collected from patients infected with P. vivax and P. falciparum. The isolates were analyzed for P. vivax dihydrofolate reductase (pvdhfr) and P. falciparum dihydrofolate reductase (pfdhfr) point mutations using various PCR-based methods. The majority of the isolates (72.9%) had wild type amino acids at five codons of pvdhfr. Amongst mutant isolates, the most common pvdhfr alleles were double mutant in 58 and 117 amino acids (58R-117N). Triple mutation in 57, 58, and 117 amino acids (57L/58R/117N) was identified for the first time in the pvdhfr gene of Iranian P. vivax isolates. All the P. falciparumsamples analyzed (n = 16) possessed a double mutant pfdhfrallele (59R/108N) and retained a wild-type mutation at position 51. This may be attributed to the fact that the falciparum malaria patients were treated using sulfadoxine-pyrimethamine (SP) in Iran. The presence of mutant haplotypes in P. vivax is worrying, but has not yet reached an alarming threshold regarding drugs such as SP. The results of this study reinforce the importance of performing a molecular surveillance by means of a continuous chemoresistance assessment. PMID:27007559

Antibody Responses to a Novel Plasmodium falciparum Merozoite Surface Protein Vaccine Correlate with Protection against Experimental Malaria Infection in Aotus Monkeys

PubMed Central

Cavanagh, David R.; Kocken, Clemens H. M.; White, John H.; Cowan, Graeme J. M.; Samuel, Kay; Dubbeld, Martin A.; der Wel, Annemarie Voorberg-van; Thomas, Alan W.; McBride, Jana S.; Arnot, David E.

2014-01-01

The Block 2 region of the merozoite surface protein-1 (MSP-1) of Plasmodium falciparum has been identified as a target of protective immunity by a combination of seroepidemiology and parasite population genetics. Immunogenicity studies in small animals and Aotus monkeys were used to determine the efficacy of recombinant antigens derived from this region of MSP-1 as a potential vaccine antigen. Aotus lemurinus griseimembra monkeys were immunized three times with a recombinant antigen derived from the Block 2 region of MSP-1 of the monkey-adapted challenge strain, FVO of Plasmodium falciparum, using an adjuvant suitable for use in humans. Immunofluorescent antibody assays (IFA) against erythrocytes infected with P. falciparum using sera from the immunized monkeys showed that the MSP-1 Block 2 antigen induced significant antibody responses to whole malaria parasites. MSP-1 Block 2 antigen-specific enzyme-linked immunosorbent assays (ELISA) showed no significant differences in antibody titers between immunized animals. Immunized animals were challenged with the virulent P. falciparum FVO isolate and monitored for 21 days. Two out of four immunized animals were able to control their parasitaemia during the follow-up period, whereas two out of two controls developed fulminating parasitemia. Parasite-specific serum antibody titers measured by IFA were four-fold higher in protected animals than in unprotected animals. In addition, peptide-based epitope mapping of serum antibodies from immunized Aotus showed distinct differences in epitope specificities between protected and unprotected animals. PMID:24421900

Malaria parasite carbonic anhydrase: inhibition of aromatic/heterocyclic sulfonamides and its therapeutic potential

PubMed Central

Krungkrai, Sudaratana R; Krungkrai, Jerapan

2011-01-01

Plasmodium falciparum (P. falciparum) is responsible for the majority of life-threatening cases of human malaria, causing 1.5-2.7 million annual deaths. The global emergence of drug-resistant malaria parasites necessitates identification and characterization of novel drug targets and their potential inhibitors. We identified the carbonic anhydrase (CA) genes in P. falciparum. The pfCA gene encodes anα-carbonic anhydrase, a Zn2+-metalloenzme, possessing catalytic properties distinct from that of the human host CA enzyme. The amino acid sequence of the pfCA enzyme is different from the analogous protozoan and human enzymes. A library of aromatic/heterocyclic sulfonamides possessing a large diversity of scaffolds were found to be very good inhibitors for the malarial enzyme at moderate-low micromolar and submicromolar inhibitions. The structure of the groups substituting the aromatic-ureido- or aromatic-azomethine fragment of the molecule and the length of the parent sulfonamide were critical parameters for the inhibitory properties of the sulfonamides. One derivative, that is, 4- (3, 4-dichlorophenylureido)thioureido-benzenesulfonamide (compound 10) was the most effective in vitro Plasmodium falciparum CA inhibitor, and was also the most effective antimalarial compound on the in vitro P. falciparum growth inhibition. The compound 10 was also effective in vivo antimalarial agent in mice infected with Plasmodium berghei, an animal model of drug testing for human malaria infection. It is therefore concluded that the sulphonamide inhibitors targeting the parasite CA may have potential for the development of novel therapies against human malaria. PMID:23569766

Use of polymerase chain reaction technique to confirm VecTest screening results in Plasmodium falciparum and Plasmodium vivax VK 210 laboratory-infected Anopheles stephensi mosquitoes.

PubMed

Santos-Ciminera, Patricia D; Acheé, Nicole L; Quinnan, Gerald V; Roberts, Donald R

2004-09-01

We evaluated polymerase chain reaction (PCR) to confirm immunoassays for malaria parasites in mosquito pools after a failure to detect malaria with PCR during an outbreak in which pools tested positive using VecTest and enzyme-linked immunosorbent assay (ELISA). We combined VecTest, ELISA, and PCR to detect Plasmodium falciparum and Plasmodium vivax VK 210. Each mosquito pool, prepared in triplicate, consisted of 1 exposed Anopheles stephensi and up to 9 unfed mosquitoes. The results of VecTest and ELISA were concordant. DNA from a subset of the pools, 1 representative of each ratio of infected to uninfected mosquitoes, was extracted and used as template in PCR. All P. vivax pools were PCR positive but some needed additional processing for removal of apparent inhibitors before positive results were obtained. One of the pools selected for P. falciparum was negative by PCR, probably because of losses or contamination during DNA extraction; 2 remaining pools at this ratio were PCR positive. Testing pools by VecTest, ELISA, and PCR is feasible, and PCR is useful for confirmation of immunoassays. An additional step might be needed to remove potential inhibitors from pools prior to PCR.

Effect of naturally occurring Wolbachia in Anopheles gambiae s.l. mosquitoes from Mali on Plasmodium falciparum malaria transmission

PubMed Central

Gomes, Fabio M.; Hixson, Bretta L.; Tyner, Miles D. W.; Ramirez, Jose Luis; Canepa, Gaspar E.; Alves e Silva, Thiago Luiz; Molina-Cruz, Alvaro; Keita, Moussa; Kane, Fouseyni; Traoré, Boïssé; Sogoba, Nafomon; Barillas-Mury, Carolina

2017-01-01

A naturally occurring Wolbachia strain (wAnga-Mali) was identified in mosquitoes of the Anopheles gambiae complex collected in the Malian villages of Dangassa and Kenieroba. Phylogenetic analysis of the nucleotide sequence of two 16S rRNA regions showed that wAnga-Mali clusters with Wolbachia strains from supergroup A and has the highest homology to a Wolbachia strain isolated from cat fleas (Ctenocephalides). wAnga-Mali is different from two Wolbachia strains previously reported in A. gambiae from Burkina Faso (wAnga_VK5_STP and wAnga_VK5_3.1a). Quantitative analysis of Wolbachia and Plasmodium sporozoite infection in field-collected mosquitoes indicates that the prevalence and intensity of Plasmodium falciparum sporozoite infection is significantly lower in Wolbachia-infected females. The presence of Wolbachia in females from a laboratory Anopheles coluzzii (A. gambiae, M form) colony experimentally infected with P. falciparum (NF54 strain) gametocyte cultures slightly enhanced oocyst infection. However, Wolbachia infection significantly reduced the prevalence and intensity of sporozoite infection, as observed in the field. This indicates that wAnga-Mali infection does not limit early stages of Plasmodium infection in the mosquito, but it has a strong deleterious effect on sporozoites and reduces malaria transmission. PMID:29114059

Integrative omics analysis. A study based on Plasmodium falciparum mRNA and protein data.

PubMed

Tomescu, Oana A; Mattanovich, Diethard; Thallinger, Gerhard G

2014-01-01

Technological improvements have shifted the focus from data generation to data analysis. The availability of large amounts of data from transcriptomics, protemics and metabolomics experiments raise new questions concerning suitable integrative analysis methods. We compare three integrative analysis techniques (co-inertia analysis, generalized singular value decomposition and integrative biclustering) by applying them to gene and protein abundance data from the six life cycle stages of Plasmodium falciparum. Co-inertia analysis is an analysis method used to visualize and explore gene and protein data. The generalized singular value decomposition has shown its potential in the analysis of two transcriptome data sets. Integrative Biclustering applies biclustering to gene and protein data. Using CIA, we visualize the six life cycle stages of Plasmodium falciparum, as well as GO terms in a 2D plane and interpret the spatial configuration. With GSVD, we decompose the transcriptomic and proteomic data sets into matrices with biologically meaningful interpretations and explore the processes captured by the data sets. IBC identifies groups of genes, proteins, GO Terms and life cycle stages of Plasmodium falciparum. We show method-specific results as well as a network view of the life cycle stages based on the results common to all three methods. Additionally, by combining the results of the three methods, we create a three-fold validated network of life cycle stage specific GO terms: Sporozoites are associated with transcription and transport; merozoites with entry into host cell as well as biosynthetic and metabolic processes; rings with oxidation-reduction processes; trophozoites with glycolysis and energy production; schizonts with antigenic variation and immune response; gametocyctes with DNA packaging and mitochondrial transport. Furthermore, the network connectivity underlines the separation of the intraerythrocytic cycle from the gametocyte and sporozoite stages. Using integrative analysis techniques, we can integrate knowledge from different levels and obtain a wider view of the system under study. The overlap between method-specific and common results is considerable, even if the basic mathematical assumptions are very different. The three-fold validated network of life cycle stage characteristics of Plasmodium falciparum could identify a large amount of the known associations from literature in only one study.

Dispensing and determinants of non-adherence to treatment for non complicated malaria caused by Plasmodium vivax and Plasmodium falciparum in high-risk municipalities in the Brazilian Amazon.

PubMed

Osorio-de-Castro, Claudia G S; Suárez-Mutis, Martha C; Miranda, Elaine S; Luz, Tatiana C B

2015-11-26

In Brazil, 99.7 % of malaria cases occur in the Amazon region. Although the number of cases is decreasing, the country accounted for almost 60 % of cases in the Americas Region, in 2013. Novel approaches for malaria treatment open the possibility of eliminating the disease, but suboptimal dispensing and lack of adherence influence treatment outcomes. The aim of this paper is to show the results on dispensing practices, non-adherence and determinants of non-adherence to treatment of non-complicated malaria. The study was conducted in six high-risk municipalities with Plasmodium vivax and Plasmodium falciparum transmission in the Brazilian Amazon and based on the theoretical framework of the Mafalda Project, which included investigation of dispensing and adherence. The World Health Organization Rapid Evaluation Method has been used to estimate sample size. Individuals over 15 years of age with malaria were approached at health facilities and invited to participate through informed consent. Data was collected in chart review forms focusing on diagnosis, Plasmodium type, prescribing, and dispensing (kind, quantity, labelling and procedures). Follow-up household interviews complemented data collection at health facility. Non-adherence was measured during the implementation phase, by self-reports and pill-counts. Analysis was descriptive and statistical tests were carried out. Determinants of non-adherence and quality of dispensing were assessed according to the literature. The study involved 165 patients. Dispensing was done according to the national guidelines. Labelling was adequate for P. vivax but inadequate for P. falciparum medicines. Non-adherent patients were 12.1 % according to self-reports and 21.8 % according to pill-counts. Results point to greater non-adherence among all P. falciparum patients and among malaria non-naîve patients. More patients informed understanding adverse effects than 'how to use' anti-malarials. Non-adherent patients were mostly those with a P. falciparum diagnosis and those in their second or more malaria episode. New taxonomies and concepts on adherence stress the importance of focusing on the individual patient. Interventions targeted to and tailored for malaria patients must be addressed by health policy and implemented by managers and clinicians.

Integrative omics analysis. A study based on Plasmodium falciparum mRNA and protein data

PubMed Central

2014-01-01

Background Technological improvements have shifted the focus from data generation to data analysis. The availability of large amounts of data from transcriptomics, protemics and metabolomics experiments raise new questions concerning suitable integrative analysis methods. We compare three integrative analysis techniques (co-inertia analysis, generalized singular value decomposition and integrative biclustering) by applying them to gene and protein abundance data from the six life cycle stages of Plasmodium falciparum. Co-inertia analysis is an analysis method used to visualize and explore gene and protein data. The generalized singular value decomposition has shown its potential in the analysis of two transcriptome data sets. Integrative Biclustering applies biclustering to gene and protein data. Results Using CIA, we visualize the six life cycle stages of Plasmodium falciparum, as well as GO terms in a 2D plane and interpret the spatial configuration. With GSVD, we decompose the transcriptomic and proteomic data sets into matrices with biologically meaningful interpretations and explore the processes captured by the data sets. IBC identifies groups of genes, proteins, GO Terms and life cycle stages of Plasmodium falciparum. We show method-specific results as well as a network view of the life cycle stages based on the results common to all three methods. Additionally, by combining the results of the three methods, we create a three-fold validated network of life cycle stage specific GO terms: Sporozoites are associated with transcription and transport; merozoites with entry into host cell as well as biosynthetic and metabolic processes; rings with oxidation-reduction processes; trophozoites with glycolysis and energy production; schizonts with antigenic variation and immune response; gametocyctes with DNA packaging and mitochondrial transport. Furthermore, the network connectivity underlines the separation of the intraerythrocytic cycle from the gametocyte and sporozoite stages. Conclusion Using integrative analysis techniques, we can integrate knowledge from different levels and obtain a wider view of the system under study. The overlap between method-specific and common results is considerable, even if the basic mathematical assumptions are very different. The three-fold validated network of life cycle stage characteristics of Plasmodium falciparum could identify a large amount of the known associations from literature in only one study. PMID:25033389

Generation of quinolone antimalarials targeting the Plasmodium falciparum mitochondrial respiratory chain for the treatment and prophylaxis of malaria

PubMed Central

Biagini, Giancarlo A.; Fisher, Nicholas; Shone, Alison E.; Mubaraki, Murad A.; Srivastava, Abhishek; Hill, Alisdair; Antoine, Thomas; Warman, Ashley J.; Davies, Jill; Pidathala, Chandrakala; Amewu, Richard K.; Leung, Suet C.; Sharma, Raman; Gibbons, Peter; Hong, David W.; Pacorel, Bénédicte; Lawrenson, Alexandre S.; Charoensutthivarakul, Sitthivut; Taylor, Lee; Berger, Olivier; Mbekeani, Alison; Stocks, Paul A.; Nixon, Gemma L.; Chadwick, James; Hemingway, Janet; Delves, Michael J.; Sinden, Robert E.; Zeeman, Anne-Marie; Kocken, Clemens H. M.; Berry, Neil G.; O’Neill, Paul M.; Ward, Stephen A.

2012-01-01

There is an urgent need for new antimalarial drugs with novel mechanisms of action to deliver effective control and eradication programs. Parasite resistance to all existing antimalarial classes, including the artemisinins, has been reported during their clinical use. A failure to generate new antimalarials with novel mechanisms of action that circumvent the current resistance challenges will contribute to a resurgence in the disease which would represent a global health emergency. Here we present a unique generation of quinolone lead antimalarials with a dual mechanism of action against two respiratory enzymes, NADH:ubiquinone oxidoreductase (Plasmodium falciparum NDH2) and cytochrome bc1. Inhibitor specificity for the two enzymes can be controlled subtly by manipulation of the privileged quinolone core at the 2 or 3 position. Inhibitors display potent (nanomolar) activity against both parasite enzymes and against multidrug-resistant P. falciparum parasites as evidenced by rapid and selective depolarization of the parasite mitochondrial membrane potential, leading to a disruption of pyrimidine metabolism and parasite death. Several analogs also display activity against liver-stage parasites (Plasmodium cynomolgi) as well as transmission-blocking properties. Lead optimized molecules also display potent oral antimalarial activity in the Plasmodium berghei mouse malaria model associated with favorable pharmacokinetic features that are aligned with a single-dose treatment. The ease and low cost of synthesis of these inhibitors fulfill the target product profile for the generation of a potent, safe, and inexpensive drug with the potential for eventual clinical deployment in the control and eradication of falciparum malaria. PMID:22566611

The effect and mechanism of inhibiting glucose-6-phosphate dehydrogenase activity on the proliferation of Plasmodium falciparum.

PubMed

Zhang, Zhiqiang; Chen, Xiaodan; Jiang, Chengrui; Fang, Zishui; Feng, Yi; Jiang, Weiying

2017-05-01

We screened >40,000 patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency and found that the G6PD Kaiping allele was under the most positive selection for fighting against malaria in the Chinese population. However, the mechanism is unknown. The current study was designed to investigate the anti-malarial effect and mechanism of G6PD deficiency. Dehydroepiandrosterone (DHEA) was utilised for inhibiting the G6PD activity of erythrocytes. Giemsa staining of blood smears and quantitative real-time PCR were used for the detection and quantification of Plasmodium falciparum infection. A transmission electron microscope was used to observe the structural changes of P. falciparum. An atomic force microscopy was used for the analyses of morphology, roughness and Young's Modulus of the infective erythrocyte membrane. When G6PD activity was inhibited by DHEA, the infection rate of P. falciparum decreased, its cell nucleus shrank, the cell organelles and metabolites were reduced gradually and the Young's Modulus of the erythrocyte membrane increased with increasing DHEA concentrations. These data indicated that Plasmodium multiplication would be inhibited in G6PD deficient erythrocytes because the Plasmodium organelles could not obtain enough nutrients, including ribose-5-phosphate and the reducing equivalent, NADPH. Moreover, the Young's Modulus of the erythrocyte membrane increased, which resulted in an increased membrane stiffness and decreased deformation. It was difficult for the merozoites to invade erythrocytes through endocytosis. Understanding these points will have a major effect on searching for new anti-malarial drug targets. Copyright © 2017 Elsevier B.V. All rights reserved.

In silico screening for Plasmodium falciparum enoyl-ACP reductase inhibitors

NASA Astrophysics Data System (ADS)

Lindert, Steffen; Tallorin, Lorillee; Nguyen, Quynh G.; Burkart, Michael D.; McCammon, J. Andrew

2015-01-01

The need for novel therapeutics against Plasmodium falciparum is urgent due to recent emergence of multi-drug resistant malaria parasites. Since fatty acids are essential for both the liver and blood stages of the malarial parasite, targeting fatty acid biosynthesis is a promising strategy for combatting P. falciparum. We present a combined computational and experimental study to identify novel inhibitors of enoyl-acyl carrier protein reductase ( PfENR) in the fatty acid biosynthesis pathway. A small-molecule database from ChemBridge was docked into three distinct PfENR crystal structures that provide multiple receptor conformations. Two different docking algorithms were used to generate a consensus score in order to rank possible small molecule hits. Our studies led to the identification of five low-micromolar pyrimidine dione inhibitors of PfENR.

To report a case of unilateral proliferative retinopathy following noncerebral malaria with Plasmodium falciparum in Southern India.

PubMed

Verma, Aditya; Krishna, M S

2015-01-01

The retinopathy in association with malaria fever described so far includes retinal hemorrhages, vessel changes, retinal discoloration/whitening and papilledema. Malaria retinopathy has been mostly described in severe cases, associated with Plasmodium falciparum, correlating the patho-physiology of retinal and cerebral manifestations. We report an unusual case of proliferative retinopathy as a manifestation of malaria fever, caused by P. falciparum with no cerebral involvement. The patient had features of unilateral retinal vascular occlusion with proliferative changes and vitreous hemorrhage. To the best of our knowledge, such a case has never been reported so far in the literature. This report highlights the possible occurrence of severe proliferative changes associated with malaria fever, which if diagnosed early can prevent possible blindness.

The heat shock protein 90 of Plasmodium falciparum and antimalarial activity of its inhibitor, geldanamycin

PubMed Central

Kumar, Rajinder; Musiyenko, Alla; Barik, Sailen

2003-01-01

Background The naturally occurring benzoquinone ansamycin compound, geldanamycin (GA), is a specific inhibitor of heat shock protein 90 (Hsp90) and is a potential anticancer agent. Since Plasmodium falciparum has been reported to have an Hsp90 ortholog, we tested the possibility that GA might inhibit it and thereby display antiparasitic activity. Results We provide direct recombinant DNA evidence for the Hsp90 protein of Plasmodium falciparum, the causative agent of fatal malaria. While the mRNA of Hsp90 was mainly expressed in ring and trophozoite stages, the protein was found in all stages, although schizonts contained relatively lower amounts. In vitro the parasitic Hsp90 exhibited an ATP-binding activity that could be specifically inhibited by GA. Plasmodium growth in human erythrocyte culture was strongly inhibited by GA with an IC50 of 20 nM, compared to the IC50 of 15 nM for chloroquine (CQ) under identical conditions. When used in combination, the two drugs acted synergistically. GA was equally effective against CQ-sensitive and CQ-resistant strains (3D7 and W2, respectively) and on all erythrocytic stages of the parasite. Conclusions Together, these results suggest that an active and essential Hsp90 chaperone cycle exists in Plasmodium and that the ansamycin antibiotics will be an important tool to dissect its role in the parasite. Additionally, the favorable pharmacology of GA, reported in human trials, makes it a promising antimalarial drug. PMID:14514358

The heat shock protein 90 of Plasmodium falciparum and antimalarial activity of its inhibitor, geldanamycin.

PubMed

Kumar, Rajinder; Musiyenko, Alla; Barik, Sailen

2003-09-15

The naturally occurring benzoquinone ansamycin compound, geldanamycin (GA), is a specific inhibitor of heat shock protein 90 (Hsp90) and is a potential anticancer agent. Since Plasmodium falciparum has been reported to have an Hsp90 ortholog, we tested the possibility that GA might inhibit it and thereby display antiparasitic activity. We provide direct recombinant DNA evidence for the Hsp90 protein of Plasmodium falciparum, the causative agent of fatal malaria. While the mRNA of Hsp90 was mainly expressed in ring and trophozoite stages, the protein was found in all stages, although schizonts contained relatively lower amounts. In vitro the parasitic Hsp90 exhibited an ATP-binding activity that could be specifically inhibited by GA. Plasmodium growth in human erythrocyte culture was strongly inhibited by GA with an IC50 of 20 nM, compared to the IC50 of 15 nM for chloroquine (CQ) under identical conditions. When used in combination, the two drugs acted synergistically. GA was equally effective against CQ-sensitive and CQ-resistant strains (3D7 and W2, respectively) and on all erythrocytic stages of the parasite. Together, these results suggest that an active and essential Hsp90 chaperone cycle exists in Plasmodium and that the ansamycin antibiotics will be an important tool to dissect its role in the parasite. Additionally, the favorable pharmacology of GA, reported in human trials, makes it a promising antimalarial drug.

Plasmodium falciparum CRK4 directs continuous rounds of DNA replication during schizogony.

PubMed

Ganter, Markus; Goldberg, Jonathan M; Dvorin, Jeffrey D; Paulo, Joao A; King, Jonas G; Tripathi, Abhai K; Paul, Aditya S; Yang, Jing; Coppens, Isabelle; Jiang, Rays H Y; Elsworth, Brendan; Baker, David A; Dinglasan, Rhoel R; Gygi, Steven P; Duraisingh, Manoj T

2017-02-17

Plasmodium parasites, the causative agents of malaria, have evolved a unique cell division cycle in the clinically relevant asexual blood stage of infection 1 . DNA replication commences approximately halfway through the intracellular development following invasion and parasite growth. The schizont stage is associated with multiple rounds of DNA replication and nuclear division without cytokinesis, resulting in a multinucleated cell. Nuclei divide asynchronously through schizogony, with only the final round of DNA replication and segregation being synchronous and coordinated with daughter cell assembly 2,3 . However, the control mechanisms for this divergent mode of replication are unknown. Here, we show that the Plasmodium-specific kinase PfCRK4 is a key cell-cycle regulator that orchestrates multiple rounds of DNA replication throughout schizogony in Plasmodium falciparum. PfCRK4 depletion led to a complete block in nuclear division and profoundly inhibited DNA replication. Quantitative phosphoproteomic profiling identified a set of PfCRK4-regulated phosphoproteins with greatest functional similarity to CDK2 substrates, particularly proteins involved in the origin of replication firing. PfCRK4 was required for initial and subsequent rounds of DNA replication during schizogony and, in addition, was essential for development in the mosquito vector. Our results identified an essential S-phase promoting factor of the unconventional P. falciparum cell cycle. PfCRK4 is required for both a prolonged period of the intraerythrocytic stage of Plasmodium infection, as well as for transmission, revealing a broad window for PfCRK4-targeted chemotherapeutics.

Comparison of Clinical Profile between P. vivax and P. falciparum Malaria in Children: A Tertiary Care Centre Perspective from India.

PubMed

Goyal, Jagdish Prasad; Makwana, Aarti M

2014-01-01

Background. Malaria is a one of the leading causes of morbidity and mortality in tropical countries. Plasmodium vivax (P. vivax) is usually thought to be causing benign malaria with low incidence of complications as compared to Plasmodium falciparum (P. falciparum). Methods. This retrospective observational study included malaria patients who were admitted to K.T. Children Hospital and P.D.U. Government Medical College, Rajkot, a tertiary care teaching hospital, Gujarat, western India, during the period January 2012 to December 2012. Inclusion criteria were patients in whom either P. falciparum or P. vivax was positive on rapid malaria antigen test and peripheral blood smear. Patients showing mixed infections were excluded from study. Results. A total of 79 subjects (mean age 5.4 ± 3.6 years) were included in the study. It consisted of 47 P. vivax and 32 P. falciparum cases. The P. vivax cases consisted of 33 (70.2%) males and 11 (19.8%) females while P. falciparum cases consisted of 14 (43.8%) males and 18 (56.2%) females. One patient of each P. vivax and P. falciparum expired. There was no statistical significant difference found between complications such as anemia, thrombocytopenia, liver and renal dysfunction, ARDS, and cerebral malaria between P. vivax and P. falciparum. Conclusion. We conclude that P. vivax monoinfection tends to have as similar course and complications as compared to malaria due to P. falciparum monoinfection.

[Presence of the double pfmdr1 mutation 86Tyr and 1246 Tyr in clones of a chloroquine-resistant west African isolate of Plasmodium falciparum].

PubMed

Pinheiro, L; Franco, S; Adagu, I S; Rosa, R; Rosário, V E; Warhurst, D C

2003-01-01

Isolates of Plasmodium falciparum from three areas of West Africa were recovered from cryopreservation and their chloroquine-sensitivity were determined in vitro. Of the 90 samples studied, 60 were from Guinea-Bissau (30Resistant/30Sensitive), 15 were from S. Tomé and Príncipe (11Resistant/4Sensitive) and 15 were from Angola (11Resistant/4Sensitive). All the isolates were sensitive to mefloquine. Using the polymerase chain reaction/restriction fragment length polymorphism technique (PCR/RFLP) it was possible to detect two mutations in the pfmdr1 gene, often associated with chloroquine-resistance. 66% of the samples from Guiné-Bissau showed a correlation with chloroquine-resistance while 73% of the samples from São Tomé and Angola altogether had the 86Tyr mutation. The present study on West African isolates and clones showed, for the first time, the presence of a double point mutation in the pfmdr1 gene one being found, up to now, only in South America isolates of Plasmodium falciparum.

UDP-galactose and acetyl-CoA transporters as Plasmodium multidrug resistance genes.

PubMed

Lim, Michelle Yi-Xiu; LaMonte, Gregory; Lee, Marcus C S; Reimer, Christin; Tan, Bee Huat; Corey, Victoria; Tjahjadi, Bianca F; Chua, Adeline; Nachon, Marie; Wintjens, René; Gedeck, Peter; Malleret, Benoit; Renia, Laurent; Bonamy, Ghislain M C; Ho, Paul Chi-Lui; Yeung, Bryan K S; Chow, Eric D; Lim, Liting; Fidock, David A; Diagana, Thierry T; Winzeler, Elizabeth A; Bifani, Pablo

2016-09-19

A molecular understanding of drug resistance mechanisms enables surveillance of the effectiveness of new antimicrobial therapies during development and deployment in the field. We used conventional drug resistance selection as well as a regime of limiting dilution at early stages of drug treatment to probe two antimalarial imidazolopiperazines, KAF156 and GNF179. The latter approach permits the isolation of low-fitness mutants that might otherwise be out-competed during selection. Whole-genome sequencing of 24 independently derived resistant Plasmodium falciparum clones revealed four parasites with mutations in the known cyclic amine resistance locus (pfcarl) and a further 20 with mutations in two previously unreported P. falciparum drug resistance genes, an acetyl-CoA transporter (pfact) and a UDP-galactose transporter (pfugt). Mutations were validated both in vitro by CRISPR editing in P. falciparum and in vivo by evolution of resistant Plasmodium berghei mutants. Both PfACT and PfUGT were localized to the endoplasmic reticulum by fluorescence microscopy. As mutations in pfact and pfugt conveyed resistance against additional unrelated chemical scaffolds, these genes are probably involved in broad mechanisms of antimalarial drug resistance.

Implications of Plasmodium vivax Biology for Control, Elimination, and Research

PubMed Central

Olliaro, Piero L.; Barnwell, John W.; Barry, Alyssa; Mendis, Kamini; Mueller, Ivo; Reeder, John C.; Shanks, G. Dennis; Snounou, Georges; Wongsrichanalai, Chansuda

2016-01-01

This paper summarizes our current understanding of the biology of Plasmodium vivax, how it differs from Plasmodium falciparum, and how these differences explain the need for P. vivax-tailored interventions. The article further pinpoints knowledge gaps where investments in research are needed to help identify and develop such specific interventions. The principal obstacles to reduce and eventually eliminate P. vivax reside in 1) its higher vectorial capacity compared with P. falciparum due to its ability to develop at lower temperature and over a shorter sporogonic cycle in the vector, allowing transmission in temperate zones and making it less sensitive to vector control measures that are otherwise effective on P. falciparum; 2) the presence of dormant liver forms (hypnozoites), sustaining multiple relapsing episodes from a single infectious bite that cannot be diagnosed and are not susceptible to any available antimalarial except primaquine, with routine deployment restricted by toxicity; 3) low parasite densities, which are difficult to detect with current diagnostics leading to missed diagnoses and delayed treatments (and protracted transmission), coupled with 4) transmission stages (gametocytes) occurring early in acute infections, before infection is diagnosed. PMID:27799636

Circulating red cell-derived microparticles in human malaria.

PubMed

Nantakomol, Duangdao; Dondorp, Arjen M; Krudsood, Srivicha; Udomsangpetch, Rachanee; Pattanapanyasat, Kovit; Combes, Valery; Grau, Georges E; White, Nicholas J; Viriyavejakul, Parnpen; Day, Nicholas P J; Chotivanich, Kesinee

2011-03-01

In patients with falciparum malaria, plasma concentrations of cell-derived microparticles correlate with disease severity. Using flow cytometry, we quantified red blood cell-derived microparticles (RMPs) in patients with malaria and identified the source and the factors associated with production. RMP concentrations were increased in patients with Plasmodium falciparum (n = 29; median, 457 RMPs/μL [range, 13-4,342 RMPs/μL]), Plasmodium vivax (n = 5; median, 409 RMPs/μL [range, 281-503/μL]), and Plasmodium malariae (n = 2; median, 163 RMPs/μL [range, 127-200 RMPs/μL]) compared with those in healthy subjects (n = 11; median, 8 RMPs/μL [range, 3-166 RMPs/μL]; P = .01). RMP concentrations were highest in patients with severe falciparum malaria (P = .01). Parasitized red cells produced >10 times more RMPs than did unparasitized cells, but the overall majority of RMPs still derived from uninfected red blood cells (URBCs). In cultures, RMP production increased as the parasites matured. Hemin and parasite products induced RMP production in URBCs, which was inhibited by N-acetylcysteine, suggesting heme-mediated oxidative stress as a pathway for the generation of RMPs.

Housing conditions and Plasmodium falciparum infection: protective effect of iron-sheet roofed houses.

PubMed

Yé, Yazoumé; Hoshen, Moshe; Louis, Valérie; Séraphin, Simboro; Traoré, Issouf; Sauerborn, Rainer

2006-02-01

Identification and better understanding of potential risk factors for malaria are important for targeted and cost-effective health interventions. Housing conditions have been suggested as one of the potential risk factors. This study aims to further investigate this risk factor, and is focused on the effect of the type of roof on Plasmodium falciparum infection among children below five years in the North West of Burkina Faso. In a cross-sectional study design, 661 children aged six to 60 months were randomly selected from three rural and one semi-urban site at the end of the rainy season (November 2003). The children were screened for fever and tested for Plasmodium falciparum infection. In addition, data on bed net use and house characteristics was collected from the household were each child lived. Using adjusted odds ratios, children living in house roofed with iron-sheet were compared with those in house with mud or grass roof. Overall P. falciparum infection prevalence was 22.8 % with a significant variation between (Chi-square, p < 0.0001). The prevalence in Cissé (33.3 %) and Goni (30.6 %) were twice times more than in Nouna (15.2 %) and Kodougou (13.2 %). After adjusting for age, sex, use of bed net and housing conditions, children living in houses with mud roofs had significantly higher risk of getting P. falciparum infection compared to those living in iron-sheet roofed houses (Odds Ratio 2.6; 95% Confidence Interval, 1.4-4.7). These results suggest that house characteristics should be taken into consideration when designing health intervention against P. falciparum infection and particular attention should be paid to children living in houses with mud roofs.

Genetic diversity and population structure of Plasmodium falciparum in Thailand, a low transmission country.

PubMed

Pumpaibool, Tepanata; Arnathau, Céline; Durand, Patrick; Kanchanakhan, Naowarat; Siripoon, Napaporn; Suegorn, Aree; Sitthi-Amorn, Chitr; Renaud, François; Harnyuttanakorn, Pongchai

2009-07-14

The population structure of the causative agents of human malaria, Plasmodium sp., including the most serious agent Plasmodium falciparum, depends on the local epidemiological and demographic situations, such as the incidence of infected people, the vector transmission intensity and migration of inhabitants (i.e. exchange between sites). Analysing the structure of P. falciparum populations at a large scale, such as continents, or with markers that are subject to non-neutral selection, can lead to a masking and misunderstanding of the effective process of transmission. Thus, knowledge of the genetic structure and organization of P. falciparum populations in a particular area with neutral genetic markers is needed to understand which epidemiological factors should be targeted for disease control. Limited reports are available on the population genetic diversity and structure of P. falciparum in Thailand, and this is of particular concern at the Thai-Myanmar and Thai-Cambodian borders, where there is a reported high resistance to anti-malarial drugs, for example mefloquine, with little understanding of its potential gene flow. The diversity and genetic differentiation of P. falciparum populations were analysed using 12 polymorphic apparently neutral microsatellite loci distributed on eight of the 14 different chromosomes. Samples were collected from seven provinces in the western, eastern and southern parts of Thailand. A strong difference in the nuclear genetic structure was observed between most of the assayed populations. The genetic diversity was comparable to the intermediate level observed in low P. falciparum transmission areas (average HS = 0.65 +/- 0.17), where the lowest is observed in South America and the highest in Africa. However, uniquely the Yala province, had only a single multilocus genotype present in all samples, leading to a strong geographic differentiation when compared to the other Thai populations during this study. Comparison of the genetic structure of P. falciparum populations in Thailand with those in the French Guyana, Congo and Cameroon revealed a significant genetic differentiation between all of them, except the two African countries, whilst the genetic variability of P. falciparum amongst countries showed overlapping distributions. Plasmodium falciparum shows genetically structured populations across local areas of Thailand. Although Thailand is considered to be a low transmission area, a relatively high level of genetic diversity and no linkage disequilibrium was found in five of the studied areas, the exception being the Yala province (Southern peninsular Thailand), where a clonal population structure was revealed and in Kanchanaburi province (Western Thailand). This finding is particularly relevant in the context of malaria control, because it could help in understanding the special dynamics of parasite populations in areas with different histories of, and exposure to, drug regimens.

Slow and fast dynamics model of a Malaria with Sickle-Cell genetic disease with multi-stage infections of the mosquitoes population

NASA Astrophysics Data System (ADS)

Dewi Siawanta, Shanti; Adi-Kusumo, Fajar; Irwan Endrayanto, Aluicius

2018-03-01

Malaria, which is caused by Plasmodium, is a common disease in tropical areas. There are three types of Plasmodium i.e. Plasmodium Vivax, Plasmodium Malariae, and Plasmodium Falciparum. The most dangerous cases of the Malaria are mainly caused by the Plasmodium Falciparum. One of the important characteristics for the Plasmodium infection is due to the immunity of erythrocyte that contains HbS (Haemoglobin Sickle-cell) genes. The individuals who has the HbS gene has better immunity against the disease. In this paper, we consider a model that shows the spread of malaria involving the interaction between the mosquitos population, the human who has HbS genes population and the human with normal gene population. We do some analytical and numerical simulation to study the basic reproduction ratio and the slow-fast dynamics of the phase-portrait. The slow dynamics in our model represents the response of the human population with HbS gene to the Malaria disease while the fast dynamics show the response of the human population with the normal gene to the disease. The slow and fast dynamics phenomena are due to the fact that the population of the individuals who have HbS gene is much smaller than the individuals who has normal genes.

Fighting malaria with engineered symbiotic bacteria from vector mosquitoes.

PubMed

Wang, Sibao; Ghosh, Anil K; Bongio, Nicholas; Stebbings, Kevin A; Lampe, David J; Jacobs-Lorena, Marcelo

2012-07-31

The most vulnerable stages of Plasmodium development occur in the lumen of the mosquito midgut, a compartment shared with symbiotic bacteria. Here, we describe a strategy that uses symbiotic bacteria to deliver antimalaria effector molecules to the midgut lumen, thus rendering host mosquitoes refractory to malaria infection. The Escherichia coli hemolysin A secretion system was used to promote the secretion of a variety of anti-Plasmodium effector proteins by Pantoea agglomerans, a common mosquito symbiotic bacterium. These engineered P. agglomerans strains inhibited development of the human malaria parasite Plasmodium falciparum and rodent malaria parasite Plasmodium berghei by up to 98%. Significantly, the proportion of mosquitoes carrying parasites (prevalence) decreased by up to 84% for two of the effector molecules, scorpine, a potent antiplasmodial peptide and (EPIP)(4), four copies of Plasmodium enolase-plasminogen interaction peptide that prevents plasminogen binding to the ookinete surface. We demonstrate the use of an engineered symbiotic bacterium to interfere with the development of P. falciparum in the mosquito. These findings provide the foundation for the use of genetically modified symbiotic bacteria as a powerful tool to combat malaria.

Molecular surveillance of Plasmodium falciparum drug resistance in the Republic of Congo: four and nine years after the introduction of artemisinin-based combination therapy.

PubMed

Koukouikila-Koussounda, Felix; Jeyaraj, Sankarganesh; Nguetse, Christian N; Nkonganyi, Charles Nchotebah; Kokou, Kossiwa Clarisse; Etoka-Beka, Mandingha K; Ntoumi, Francine; Velavan, Thirumalaisamy P

2017-04-19

Resistance to anti-malarial drugs hinders efforts on malaria elimination and eradication. Following the global spread of chloroquine-resistant parasites, the Republic of Congo adopted artemisinin-based combination therapy (ACT) in 2006 as a first-line treatment for uncomplicated malaria. To assess the impacts after implementation of ACT, a molecular surveillance for anti-malarial drug resistance was conducted in Congo 4 and 9 years after the introduction of ACT. Blood samples of 431 febrile children aged 1-10 years were utilized from two previous studies conducted in 2010 (N = 311) and 2015 (N = 120). All samples were screened for malaria parasites using nested PCR. Direct sequencing was used to determine the frequency distribution of genetic variants in the anti-malarial drug-resistant Plasmodium falciparum genes (Pfcrt, Pfmdr1, Pfatp6, Pfk13) in malaria-positive isolates. One-hundred and nineteen (N = 70 from 2010 and N = 49 from 2015) samples were positive for P. falciparum. A relative decrease in the proportion of chloroquine-resistant haplotype (CVIET) from 100% in 2005, 1 year before the introduction and implementation of ACT in 2006, to 98% in 2010 to 71% in 2015 was observed. Regarding the multidrug transporter gene, a considerable reduction in the frequency of the mutations N86Y (from 73 to 27%) and D1246Y (from 22 to 0%) was observed. However, the prevalence of the Y184F mutation remained stable (49% in 2010 compared to 54% in 2015). Isolates carrying the Pfatp6 H243Y was 25% in 2010 and this frequency was reduced to null in 2015. None of the parasites harboured the Pfk13 mutations associated with prolonged artemisinin clearance in Southeast Asia. Nevertheless, 13 new Pfk13 variants are reported among the investigated isolates. The implementation of ACT has led to the decline in prevalence of chloroquine-resistant parasites in the Republic of Congo. However, the constant prevalence of the PfMDR1 Y184F mutation, associated with lumefantrine susceptibility, indicate a selective drug pressure still exists. Taken together, this study could serve as the basis for epidemiological studies monitoring the distribution of molecular markers of artemisinin resistance in the Republic of Congo.

Plasma uric acid levels correlate with inflammation and disease severity in Malian children with Plasmodium falciparum malaria.

PubMed

Lopera-Mesa, Tatiana M; Mita-Mendoza, Neida K; van de Hoef, Diana L; Doumbia, Saibou; Konaté, Drissa; Doumbouya, Mory; Gu, Wenjuan; Traoré, Karim; Diakité, Seidina A S; Remaley, Alan T; Anderson, Jennifer M; Rodriguez, Ana; Fay, Michael P; Long, Carole A; Diakité, Mahamadou; Fairhurst, Rick M

2012-01-01

Plasmodium falciparum elicits host inflammatory responses that cause the symptoms and severe manifestations of malaria. One proposed mechanism involves formation of immunostimulatory uric acid (UA) precipitates, which are released from sequestered schizonts into microvessels. Another involves hypoxanthine and xanthine, which accumulate in parasitized red blood cells (RBCs) and may be converted by plasma xanthine oxidase to UA at schizont rupture. These two forms of 'parasite-derived' UA stimulate immune cells to produce inflammatory cytokines in vitro. We measured plasma levels of soluble UA and inflammatory cytokines and chemokines (IL-6, IL-10, sTNFRII, MCP-1, IL-8, TNFα, IP-10, IFNγ, GM-CSF, IL-1β) in 470 Malian children presenting with uncomplicated malaria (UM), non-cerebral severe malaria (NCSM) or cerebral malaria (CM). UA levels were elevated in children with NCSM (median 5.74 mg/dl, 1.21-fold increase, 95% CI 1.09-1.35, n = 23, p = 0.0007) and CM (median 5.69 mg/dl, 1.19-fold increase, 95% CI 0.97-1.41, n = 9, p = 0.0890) compared to those with UM (median 4.60 mg/dl, n = 438). In children with UM, parasite density and plasma creatinine levels correlated with UA levels. These UA levels correlated with the levels of seven cytokines [IL-6 (r = 0.259, p<0.00001), IL-10 (r = 0.242, p<0.00001), sTNFRII (r = 0.221, p<0.00001), MCP-1 (r = 0.220, p<0.00001), IL-8 (r = 0.147, p = 0.002), TNFα (r = 0.132, p = 0.006) and IP-10 (r = 0.120, p = 0.012)]. In 39 children, UA levels were 1.49-fold (95% CI 1.34-1.65; p<0.0001) higher during their malaria episode [geometric mean titer (GMT) 4.67 mg/dl] than when they were previously healthy and aparasitemic (GMT 3.14 mg/dl). Elevated UA levels may contribute to the pathogenesis of P. falciparum malaria by activating immune cells to produce inflammatory cytokines. While this study cannot identify the cause of elevated UA levels, their association with parasite density and creatinine levels suggest that parasite-derived UA and renal function may be involved. Defining pathogenic roles for parasite-derived UA precipitates, which we have not directly studied here, requires further investigation. ClinicalTrials.gov NCT00669084.

Diagnostic challenges and case management of the first imported case of Plasmodium knowlesi in Sri Lanka.

PubMed

Dewanee Ranaweera, A; Danansuriya, Manjula N; Pahalagedera, Kusumawathie; de A W Gunasekera, W M Kumudunayana T; Dharmawardena, Priyani; Mak, Keng Wai; Wong, Pei-Sze Jeslyn; Li, Mei-Zhi Irene; Tan, Cheong Huat; Hapuarachchi, Hapuarachchige C; Herath, Hema D B; Fernando, Deepika

2017-03-21

Sri Lanka has achieved 'malaria-free' status and is now in the phase of prevention of re-introduction of malaria. Imported malaria remains a challenge to resurgence of the disease. The diagnostic challenges encountered and the rapid response initiated to manage a Plasmodium infection, which was later confirmed as Plasmodium knowlesi, the first reported case from Sri Lanka, is discussed. An army officer who returned from Malaysia in October 2016 was found to be positive for Plasmodium both by microscopy and rapid diagnostic test (RDT) by the Anti Malaria Campaign Sri Lanka (AMC) during his third visit to a health care provider. Microscopy findings were suspicious of P. knowlesi infection as the smears showed parasite stages similar to both Plasmodium malariae and Plasmodium falciparum. Nested PCR at AMC confirmed Plasmodium genus, but not the species. In the absence of species confirmation, the patient was treated as a case of P. falciparum. The presence of P. knowlesi was later confirmed by a semi-nested PCR assay performed at the Environmental Health Institute, National Environmental Agency in Singapore. The parasite strain was also characterized by sequencing the circumsporozoite gene. Extensive case investigation including parasitological and entomological surveillance was carried out. Plasmodium knowlesi should be suspected in patients returning from countries in the South Asian region where the parasite is prevalent and when blood smear results are inconclusive.

Artemisinin resistance-associated polymorphisms at the K13-propeller locus are absent in Plasmodium falciparum isolates from Haiti.

PubMed

Carter, Tamar E; Boulter, Alexis; Existe, Alexandre; Romain, Jean R; St Victor, Jean Yves; Mulligan, Connie J; Okech, Bernard A

2015-03-01

Antimalarial drugs are a key tool in malaria elimination programs. With the emergence of artemisinin resistance in southeast Asia, an effort to identify molecular markers for surveillance of resistant malaria parasites is underway. Non-synonymous mutations in the kelch propeller domain (K13-propeller) in Plasmodium falciparum have been associated with artemisinin resistance in samples from southeast Asia, but additional studies are needed to characterize this locus in other P. falciparum populations with different levels of artemisinin use. Here, we sequenced the K13-propeller locus in 82 samples from Haiti, where limited government oversight of non-governmental organizations may have resulted in low-level use of artemisinin-based combination therapies. We detected a single-nucleotide polymorphism (SNP) at nucleotide 1,359 in a single isolate. Our results contribute to our understanding of the global genomic diversity of the K13-propeller locus in P. falciparum populations. © The American Society of Tropical Medicine and Hygiene.

Factors affecting exflagellation of in vitro-cultivated Plasmodium falciparum gametocytes.

PubMed

Ogwan'g, R A; Mwangi, J K; Githure, J; Were, J B; Roberts, C R; Martin, S K

1993-07-01

The environment of Plasmodium falciparum gametocytes changes when they make the transition from the vertebrate to the invertebrate host. Gametocytes of this species cultivated in vitro were used to evaluate the effect of serum, pH, pCO2 tension, bicarbonate ion, and temperature on gamete formation. Temperature was the only factor responsible for keeping P. falciparum gametocytes in the inactivated state. Mature gametocytes held at temperatures above 30 degrees C remained quiescent in 10% serum, even at low ambient pCO2 tension, alkaline pH, and in the presence of 25 mM bicarbonate ion. When the temperature of the medium was allowed to drop below 30 degrees C, gametocytes emerged from the red blood cells and microgametocytes consistently exflagellated at pH 7.4, even in the absence of bicarbonate ion. With regard to bicarbonate ion, exflagellation in P. falciparum is similar to P. berghei and different from P. gallinaceum gametocytes, which have an obligate requirement for bicarbonate ion.

A transgenic Plasmodium falciparum NF54 strain that expresses GFP-luciferase throughout the parasite life cycle.

PubMed

Vaughan, Ashley M; Mikolajczak, Sebastian A; Camargo, Nelly; Lakshmanan, Viswanathan; Kennedy, Mark; Lindner, Scott E; Miller, Jessica L; Hume, Jen C C; Kappe, Stefan H I

2012-12-01

Plasmodium falciparum is the pathogenic agent of the most lethal of human malarias. Transgenic P. falciparum parasites expressing luciferase have been created to study drug interventions of both asexual and sexual blood stages but luciferase-expressing mosquito stage and liver stage parasites have not been created which has prevented the easy quantification of mosquito stage development (e.g. for transmission blocking interventions) and liver stage development (for interventions that prevent infection). To overcome this obstacle, we have created a transgenic P. falciparum NF54 parasite that expresses a GFP-luciferase transgene throughout the life cycle. Luciferase expression is robust and measurable at all life cycle stages, including midgut oocyst, salivary gland sporozoites and liver stages, where in vivo development is easily measurable using humanized mouse infections in conjunction with an in vivo imaging system. This parasite reporter strain will accelerate testing of interventions against pre-erythrocytic life cycle stages. Copyright © 2012 Elsevier B.V. All rights reserved.

The Rheopathobiology of Plasmodium vivax and Other Important Primate Malaria Parasites.

PubMed

Russell, Bruce M; Cooke, Brian M

2017-04-01

Our current understanding of how malaria parasites remodel their host red blood cells (RBCs) and ultimately cause disease is largely based on studies of Plasmodium falciparum. In this review, we expand our knowledge to include what is currently known about pathophysiological changes to RBCs that are infected by non-falciparum malaria parasites. We highlight the potential folly of making generalizations about the rheology of malaria infection, and emphasize the need for more systematic studies into the erythrocytic biology of non-falciparum malaria parasites. We propose that a better understanding of the mechanisms that underlie the changes to RBCs induced by malaria parasites other than P. falciparum may be highly informative for the development of therapeutics that specifically disrupt the altered rheological profile of RBCs infected with either sexual- or asexual-stage parasites, resulting in drugs that block transmission, reduce disease severity, and help delay the onset of resistance to current and future anti-malaria drugs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Molecular Mechanistic Insights into the Endothelial Receptor Mediated Cytoadherence of Plasmodium falciparum-Infected Erythrocytes

PubMed Central

Li, Ang; Lim, Tong Seng; Shi, Hui; Yin, Jing; Tan, Swee Jin; Li, Zhengjun; Low, Boon Chuan; Tan, Kevin Shyong Wei; Lim, Chwee Teck

2011-01-01

Cytoadherence or sequestration is essential for the pathogenesis of the most virulent human malaria species, Plasmodium falciparum (P. falciparum). Similar to leukocyte-endothelium interaction in response to inflammation, cytoadherence of P. falciparum infected red blood cells (IRBCs) to endothelium occurs under physiological shear stresses in blood vessels and involves an array of molecule complexes which cooperate to form stable binding. Here, we applied single-molecule force spectroscopy technique to quantify the dynamic force spectra and characterize the intrinsic kinetic parameters for specific ligand-receptor interactions involving two endothelial receptor proteins: thrombospondin (TSP) and CD36. It was shown that CD36 mediated interaction was much more stable than that mediated by TSP at single molecule level, although TSP-IRBC interaction appeared stronger than CD36-IRBC interaction in the high pulling rate regime. This suggests that TSP-mediated interaction may initiate cell adhesion by capturing the fast flowing IRBCs whereas CD36 functions as the ‘holder’ for providing stable binding. PMID:21437286

South-East Asian strains of Plasmodium falciparum display higher ratio of non-synonymous to synonymous polymorphisms compared to African strains

PubMed Central

Singh, Gajinder Pal; Sharma, Amit

2016-01-01

Resistance to frontline anti-malarial drugs, including artemisinin, has repeatedly arisen in South-East Asia, but the reasons for this are not understood. Here we test whether evolutionary constraints on Plasmodium falciparum strains from South-East Asia differ from African strains. We find a significantly higher ratio of non-synonymous to synonymous polymorphisms in P. falciparum from South-East Asia compared to Africa, suggesting differences in the selective constraints on P. falciparum genome in these geographical regions. Furthermore, South-East Asian strains showed a higher proportion of non-synonymous polymorphism at conserved positions, suggesting reduced negative selection. There was a lower rate of mixed infection by multiple genotypes in samples from South-East Asia compared to Africa. We propose that a lower mixed infection rate in South-East Asia reduces intra-host competition between the parasite clones, reducing the efficiency of natural selection. This might increase the probability of fixation of fitness-reducing mutations including drug resistant ones. PMID:27853513

Genotype comparison of Plasmodium vivax and Plasmodium falciparum clones from pregnant and non-pregnant populations in North-west Colombia

PubMed Central

2012-01-01

Background Placental malaria is the predominant pathology secondary to malaria in pregnancy, causing substantial maternal and infant morbidity and mortality in tropical areas. While it is clear that placental parasites are phenotypically different from those in the peripheral circulation, it is not known whether unique genotypes are associated specifically with placental infection or perhaps more generally with pregnancy. In this study, genetic analysis was performed on Plasmodium vivax and Plasmodium falciparum parasites isolated from peripheral and placental blood in pregnant women living in North-west Colombia, and compared with parasites causing acute malaria in non-pregnant populations. Methods A total of 57 pregnant women at delivery with malaria infection confirmed by real-time PCR in peripheral or placental blood were included, as well as 50 pregnant women in antenatal care and 80 men or non-pregnant women with acute malaria confirmed by a positive thick smear for P. vivax or P. falciparum. Five molecular markers per species were genotyped by nested PCR and capillary electrophoresis. Genetic diversity and the fixation index FST per species and study group were calculated and compared. Results Almost all infections at delivery were asymptomatic with significantly lower levels of infection compared with the groups with acute malaria. Expected heterozygosity for P. vivax molecular markers ranged from 0.765 to 0.928 and for P. falciparum markers ranged from 0.331 to 0.604. For P. vivax infections, the genetic diversity was similar amongst the four study groups and the fixation index from each pairwise comparison failed to show significant genetic differentiation. For P. falciparum, no genetic differentiation was observed between placental and peripheral parasites from the same woman at delivery, but the parasites isolated at delivery showed significant genetic differentiation compared with parasites isolated from subjects with acute malaria. Conclusions In North-west Colombia, P. vivax parasites have high genetic diversity that is equivalent in pregnant and non-pregnant populations as well as in symptomatic and asymptomatic infections. For P. falciparum, the overall genetic diversity is lower, with specific genotypes associated with asymptomatic infections at delivery. PMID:23181896

Antiplasmodial activity of two medicinal plants against clinical isolates of Plasmodium falciparum and Plasmodium berghei infected mice.

PubMed

Attemene, Serge David Dago; Beourou, Sylvain; Tuo, Karim; Gnondjui, Albert Alloh; Konate, Abibatou; Toure, Andre Offianan; Kati-Coulibaly, Seraphin; Djaman, Joseph Alico

2018-03-01

Malaria is an infectious and deadly parasitic disease, associated with fever, anaemia and other ailments. Unfortunately the upsurge of plasmodium multidrug resistant constrained researchers to look for new effective drugs. Medicinal plants seem to be an unquenchable source of bioactive principles in the treatment of various diseases. The aim of this study was to assess the antiplasmodial activity of two Ivorian medicinal plants. The in vitro activity was evaluated against clinical isolates and Plasmodium falciparum K1 multidrug resistant strain using the fluorescence based SYBR green I assay. The in vivo bioassay was carried out using the classical 4 day suppressive and curative tests on Plasmodium berghei infected mice. Results showed that the in vitro bioassay of both plant extracts were found to exhibit a promising and moderate antiparasitic effects on clinical isolates (5 µg/mL < IC 50  < 15 µg/mL) and Plasmodium falciparum multidrug resistant K1 strain (15 µg/mL < IC 50  < 50 µg/mL). Furthermore, the in vivo antiplasmodial screening of both extracts showed a significant decrease in parasitemia, which was dose-dependent. Body temperature in mice treated with both extracts at experimental doses increased, compared to the negative control group and was dose-dependent. As for mice body weight a significant decrease ( p  < 0.001) was noticed in the negative control group compared to tested groups of animals. The hydroethanolic stem bark extract of Anthocleista djalonensis A Chev and leaves extract of Ziziphus mauritiana Lam exhibited anti-malarial activities. Therefore, the bioactive compounds of both plant extracts need to be investigated.

Platelets activate a pathogenic response to blood-stage Plasmodium infection but not a protective immune response.

PubMed

Gramaglia, Irene; Velez, Joyce; Combes, Valery; Grau, Georges E R; Wree, Melanie; van der Heyde, Henri C

2017-03-23

Clinical studies indicate that thrombocytopenia correlates with the development of severe falciparum malaria, suggesting that platelets either contribute to control of parasite replication, possibly as innate parasite killer cells or function in eliciting pathogenesis. Removal of platelets by anti-CD41 mAb treatment, platelet inhibition by aspirin, and adoptive transfer of wild-type (WT) platelets to CD40-KO mice, which do not control parasite replication, resulted in similar parasitemia compared with control mice. Human platelets at a physiologic ratio of 1 platelet to 9 red blood cells (RBCs) did not inhibit the in vitro development or replication of blood-stage Plasmodium falciparum The percentage of Plasmodium -infected (iRBCs) with bound platelets during the ascending parasitemia in Plasmodium chabaudi - and Plasmodium berghei -infected mice and the 48-hour in vitro cycle of P falciparum was <10%. P chabaudi and P berghei iRBCs with apoptotic parasites (TdT + ) exhibited minimal platelet binding (<5%), which was similar to nonapoptotic iRBCs. These findings collectively indicate platelets do not kill bloodstage Plasmodium at physiologically relevant effector-to-target ratios. P chabaudi primary and secondary parasitemia was similar in mice depleted of platelets by mAb-injection just before infection, indicating that activation of the protective immune response does not require platelets. In contrast to the lack of an effect on parasite replication, adoptive transfer of WT platelets to CD40-KO mice, which are resistant to experimental cerebral malaria, partially restored experimental cerebral malaria mortality and symptoms in CD40-KO recipients, indicating platelets elicit pathogenesis and platelet CD40 is a key molecule. © 2017 by The American Society of Hematology.

Discrete-Event Simulation Models of Plasmodium falciparum Malaria

PubMed Central

McKenzie, F. Ellis; Wong, Roger C.; Bossert, William H.

2008-01-01

We develop discrete-event simulation models using a single “timeline” variable to represent the Plasmodium falciparum lifecycle in individual hosts and vectors within interacting host and vector populations. Where they are comparable our conclusions regarding the relative importance of vector mortality and the durations of host immunity and parasite development are congruent with those of classic differential-equation models of malaria, epidemiology. However, our results also imply that in regions with intense perennial transmission, the influence of mosquito mortality on malaria prevalence in humans may be rivaled by that of the duration of host infectivity. PMID:18668185

The MSPDBL2 codon 591 polymorphism is associated with lumefantrine in vitro drug responses in Plasmodium falciparum isolates from Kilifi, Kenya.

PubMed

Ochola-Oyier, Lynette Isabella; Okombo, John; Mwai, Leah; Kiara, Steven M; Pole, Lewa; Tetteh, Kevin K A; Nzila, Alexis; Marsh, Kevin

2015-03-01

The mechanisms of drug resistance development in the Plasmodium falciparum parasite to lumefantrine (LUM), commonly used in combination with artemisinin, are still unclear. We assessed the polymorphisms of Pfmspdbl2 for associations with LUM activity in a Kenyan population. MSPDBL2 codon 591S was associated with reduced susceptibility to LUM (P = 0.04). The high frequency of Pfmspdbl2 codon 591S in Kenya may be driven by the widespread use of lumefantrine in artemisinin combination therapy (Coartem). Copyright © 2015, Ochola-Oyier et al.

Crystal structure of phosphoethanolamine methyltransferase from Plasmodium falciparum in complex with amodiaquine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Soon Goo; Alpert, Tara D.; Jez, Joseph M.

2012-07-17

Phosphoethanolamine N-methyltransferase (PMT) is essential for phospholipid biogenesis in the malarial parasite Plasmodium falciparum. PfPMT catalyzes the triple methylation of phosphoethanolamine to produce phosphocholine, which is then used for phosphatidylcholine synthesis. Here we describe the 2.0 {angstrom} resolution X-ray crystal structure of PfPMT in complex with amodiaquine. To better characterize inhibition of PfPMT by amodiaquine, we determined the IC{sub 50} values of a series of aminoquinolines using a direct radiochemical assay. Both structural and functional analyses provide a possible approach for the development of new small molecule inhibitors of PfPMT.

Structure-activity relationships amongst 4-position quinoline methanol antimalarials that inhibit the growth of drug sensitive and resistant strains of Plasmodium falciparum.

PubMed

Milner, Erin; McCalmont, William; Bhonsle, Jayendra; Caridha, Diana; Carroll, Dustin; Gardner, Sean; Gerena, Lucia; Gettayacamin, Montip; Lanteri, Charlotte; Luong, Thulan; Melendez, Victor; Moon, Jay; Roncal, Norma; Sousa, Jason; Tungtaeng, Anchalee; Wipf, Peter; Dow, Geoffrey

2010-02-15

Utilizing mefloquine as a scaffold, a next generation quinoline methanol (NGQM) library was constructed to identify early lead compounds that possess biological properties consistent with the target product profile for malaria chemoprophylaxis while reducing permeability across the blood-brain barrier. The library of 200 analogs resulted in compounds that inhibit the growth of drug sensitive and resistant strains of Plasmodium falciparum. Herein we report selected chemotypes and the emerging structure-activity relationship for this library of quinoline methanols. Published by Elsevier Ltd.

Assessing the asymptomatic reservoir and dihydroartemisinin-piperaquine effectiveness in a low transmission setting threatened by artemisinin resistant Plasmodium falciparum.

PubMed

Falq, Grégoire; Van Den Bergh, Rafael; De Smet, Martin; Etienne, William; Nguon, Chea; Rekol, Huy; Imwong, Mallika; Dondorp, Arjen; Kindermans, Jean-Marie

2016-09-01

In Cambodia, elimination of artemisinin resistance through direct elimination of the Plasmodium falciparum parasite may be the only strategy. Prevalence and incidence at district and village levels were assessed in Chey Saen district, Preah Vihear province, North of Cambodia. Molecular and clinical indicators for artemisinin resistance were documented. A cross sectional prevalence survey was conducted at village level in the district of Chey Saen from September to October 2014. Plasmodium spp. was assessed with high volume quantitative real-time polymerase chain reaction (qPCR). Plasmodium falciparum-positive samples were screened for mutations in the k13-propeller domain gene. Treatment effectiveness was established after 28 days (D28) using the same qPCR technique. Data from the provincial surveillance system targeting symptomatic cases, supported by Médecins Sans Frontières (MSF), were used to assess incidence. District P. falciparum prevalence was of 0.74 % [0.41; 1.21]; village prevalence ranged from 0 to 4.6 % [1.4; 10.5]. The annual incidence of P. falciparum was 16.8 cases per 1000 inhabitants in the district; village incidence ranged from 1.3 to 54.9 for 1000 inhabitants. Two geographical clusters with high number of cases were identified by both approaches. The marker for artemisinin resistance was found in six samples out of the 11 tested (55 %). 34.9 % of qPCR blood analysis of symptomatic patients were still positive at D28. The overall low prevalence of P. falciparum was confirmed in Chey Saen district in Cambodia, while there were important variations between villages. Symptomatic cases had a different pattern and were likely acquired outside the villages. It illustrates the importance of prevalence surveys in targeting interventions for elimination. Mutations in the k13-propeller domain gene (C580Y), conferring artemisinin resistance, were highly prevalent in both symptomatic and asymptomatic cases (realizing the absolute figures remain low). Asymptomatic individuals could be an additional reservoir for artemisinin resistance. The low effectiveness of dihydroartemisinin-piperaquine (DHA-PPQ) for symptomatic cases indicates that PPQ is no longer able to complement the reduced potency of DHA to treat falciparum malaria and highlights the need for an alternative first-line treatment.

Methylene blue induced morphological deformations in Plasmodium falciparum gametocytes: implications for transmission-blocking.

PubMed

Wadi, Ishan; Pillai, C Radhakrishna; Anvikar, Anupkumar R; Sinha, Abhinav; Nath, Mahendra; Valecha, Neena

2018-01-08

Malaria remains a global health problem despite availability of effective tools. For malaria elimination, drugs targeting sexual stages of Plasmodium falciparum need to be incorporated in treatment regimen along with schizonticidal drugs to interrupt transmission. Primaquine is recommended as a transmission blocking drug for its effect on mature gametocytes but is not extensively utilized because of associated safety concerns among glucose-6-phosphate dehydrogenase (G6PD) deficient patients. In present work, methylene blue, which is proposed as an alternative to primaquine is investigated for its gametocytocidal activity amongst Indian field isolates. An effort has been made to establish Indian field isolates of P. falciparum as in vitro model for gametocytocidal drugs screening. Plasmodium falciparum isolates were adapted to in vitro culture and induced to gametocyte production by hypoxanthine and culture was enriched for gametocyte stages using N-acetyl-glucosamine. Gametocytes were incubated with methylene blue for 48 h and stage specific gametocytocidal activity was evaluated by microscopic examination. Plasmodium falciparum field isolates RKL-9 and JDP-8 were able to reproducibly produce gametocytes in high yield and were used to screen gametocytocidal drugs. Methylene blue was found to target gametocytes in a concentration dependent manner by either completely eliminating gametocytes or rendering them morphologically deformed with mean IC 50 (early stages) as 424.1 nM and mean IC 50 (late stages) as 106.4 nM. These morphologically altered gametocytes appeared highly degenerated having shrinkage, distortions and membrane deformations. Field isolates that produce gametocytes in high yield in vitro can be identified and used to screen gametocytocidal drugs. These isolates should be used for validation of gametocytocidal hits obtained previously by using lab adapted reference strains. Methylene blue was found to target gametocytes produced from Indian field isolates and is proposed to be used as a gametocytocidal adjunct with artemisinin-based combination therapy. Further exploration of methylene blue in clinical studies amongst Indian population, including G6PD deficient patients, is recommended.

Efficacy of chloroquine, amodiaquine and sulphadoxine-pyrimethamine for the treatment of uncomplicated falciparum malaria: revisiting molecular markers in an area of emerging AQ and SP resistance in Mali

PubMed Central

Tekete, Mamadou; Djimde, Abdoulaye A; Beavogui, Abdoul H; Maiga, Hamma; Sagara, Issaka; Fofana, Bakary; Ouologuem, Dinkorma; Dama, Souleymane; Kone, Aminatou; Dembele, Demba; Wele, Mamadou; Dicko, Alassane; Doumbo, Ogobara K

2009-01-01

Background To update the National Malaria Control Programme of Mali on the efficacy of chloroquine, amodiaquine and sulphadoxine-pyrimethamine in the treatment of uncomplicated falciparum malaria. Methods During the malaria transmission seasons of 2002 and 2003, 455 children – between six and 59 months of age, with uncomplicated malaria in Kolle, Mali, were randomly assigned to one of three treatment arms. In vivo outcomes were assessed using WHO standard protocols. Genotyping of msp1, msp2 and CA1 polymorphisms were used to distinguish reinfection from recrudescent parasites (molecular correction). Results Day 28 adequate clinical and parasitological responses (ACPR) were 14.1%, 62.3% and 88.9% in 2002 and 18.2%, 60% and 85.2% in 2003 for chloroquine, amodiaquine and sulphadoxine-pyrimethamine, respectively. After molecular correction, ACPRs (cACPR) were 63.2%, 88.5% and 98.0% in 2002 and 75.5%, 85.2% and 96.6% in 2003 for CQ, AQ and SP, respectively. Amodiaquine was the most effective on fever. Amodiaquine therapy selected molecular markers for chloroquine resistance, while in the sulphadoxine-pyrimethamine arm the level of dhfr triple mutant and dhfr/dhps quadruple mutant increased from 31.5% and 3.8% in 2002 to 42.9% and 8.9% in 2003, respectively. No infection with dhps 540E was found. Conclusion In this study, treatment with sulphadoxine-pyrimethamine emerged as the most efficacious on uncomplicated falciparum malaria followed by amodiaquine. The study demonstrated that sulphadoxine-pyrimethamine and amodiaquine were appropriate partner drugs that could be associated with artemisinin derivatives in an artemisinin-based combination therapy. PMID:19245687

Histone deacetylases play a major role in the transcriptional regulation of the Plasmodium falciparum life cycle.

PubMed

Chaal, Balbir K; Gupta, Archna P; Wastuwidyaningtyas, Brigitta D; Luah, Yen-Hoon; Bozdech, Zbynek

2010-01-22

The apparent paucity of molecular factors of transcriptional control in the genomes of Plasmodium parasites raises many questions about the mechanisms of life cycle regulation in these malaria parasites. Epigenetic regulation has been suggested to play a major role in the stage specific gene expression during the Plasmodium life cycle. To address some of these questions, we analyzed global transcriptional responses of Plasmodium falciparum to a potent inhibitor of histone deacetylase activities (HDAC). The inhibitor apicidin induced profound transcriptional changes in multiple stages of the P. falciparum intraerythrocytic developmental cycle (IDC) that were characterized by rapid activation and repression of a large percentage of the genome. A major component of this response was induction of genes that are otherwise suppressed during that particular stage of the IDC or specific for the exo-erythrocytic stages. In the schizont stage, apicidin induced hyperacetylation of histone lysine residues H3K9, H4K8 and the tetra-acetyl H4 (H4Ac4) and demethylation of H3K4me3. Interestingly, we observed overlapping patterns of chromosomal distributions between H4K8Ac and H3K4me3 and between H3K9Ac and H4Ac4. There was a significant but partial association between the apicidin-induced gene expression and histone modifications, which included a number of stage specific transcription factors. Taken together, inhibition of HDAC activities leads to dramatic de-regulation of the IDC transcriptional cascade, which is a result of both disruption of histone modifications and up-regulation of stage specific transcription factors. These findings suggest an important role of histone modification and chromatin remodeling in transcriptional regulation of the Plasmodium life cycle. This also emphasizes the potential of P. falciparum HDACs as drug targets for malaria chemotherapy.

AQ-13, an investigational antimalarial, versus artemether plus lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria: a randomised, phase 2, non-inferiority clinical trial.

PubMed

Koita, Ousmane A; Sangaré, Lansana; Miller, Haiyan D; Sissako, Aliou; Coulibaly, Moctar; Thompson, Trevor A; Fongoro, Saharé; Diarra, Youssouf; Ba, Mamadou; Maiga, Ababacar; Diallo, Boubakar; Mushatt, David M; Mather, Frances J; Shaffer, Jeffrey G; Anwar, Asif H; Krogstad, Donald J

2017-12-01

Chloroquine was used for malaria treatment until resistant Plasmodium falciparum was identified. Because 4-aminoquinolines with modified side chains, such as AQ-13, are active against resistant parasites, we compared AQ-13 against artemether plus lumefantrine for treatment of uncomplicated P falciparum malaria. We did a randomised, non-inferiority trial. We screened men (≥18 years) with uncomplicated malaria in Missira (northeast Mali) and Bamako (capital of Mali) for eligibility (≥2000 asexual P falciparum parasites per μL of blood). Eligible participants were randomly assigned to either the artemether plus lumefantrine group or AQ-13 group by permuting blocks of four with a random number generator. Physicians and others caring for the participants were masked, except for participants who received treatment and the research pharmacist who implemented the randomisation and provided treatment. Participants received either 80 mg of oral artemether and 480 mg of oral lumefantrine twice daily for 3 days or 638·50 mg of AQ-13 base (two oral capsules) on days 1 and 2, and 319·25 mg base (one oral capsule) on day 3. Participants were monitored for parasite clearance (50 μL blood samples twice daily at 12 h intervals until two consecutive negative samples were obtained) and interviewed for adverse events (once every day) as inpatients during week 1. During the 5-week outpatient follow-up, participants were examined for adverse events and recurrent infection twice per week. All participants were included in the intention-to-treat analysis and per-protocol analysis, except for those who dropped out in the per-protocol analysis. The composite primary outcome was clearance of asexual parasites and fever by day 7, and absence of recrudescent infection by parasites with the same molecular markers from days 8 to 42 (defined as cure). Non-inferiority was considered established if the proportion of patients who were cured was higher for artemether plus lumefantrine than for AQ-13 and the upper limit of the 95% CI was less than the non-inferiority margin of 15%. This trial is registered at ClinicalTrials.gov, number NCT01614964. Between Aug 6 and Nov 18, 2013, and between Sept 18 and Nov 20, 2015, 66 Malian men with uncomplicated malaria were enrolled. 33 participants were randomly assigned to each group. There were no serious adverse events (grade 2-4) and asexual parasites were cleared by day 7 in both groups. 453 less-severe adverse events (≤grade 1) were reported: 214 in the combination group and 239 in the AQ-13 group. Two participants withdrew from the AQ-13 group after parasite clearance and three were lost to follow-up. In the artemether plus lumefantrine group, two participants had late treatment failures (same markers as original isolates). On the basis of the per-protocol analysis, the AQ-13 and artemether plus lumefantrine groups had similar proportions cured (28 [100%] of 28 vs 31 [93·9%] of 33; p=0·50) and AQ-13 was not inferior to artemether plus lumefantrine (difference -6·1%, 95% CI -14·7 to 2·4). Proportions cured were also similar between the groups in the intention-to-treat analysis (28 of 33, 84·8% for AQ-13 vs 31 of 33, 93·9% for artemether and lumefantrine; p=0·43) but the upper bound of the 95% CI exceeded the 15% non-inferiority margin (difference 9·1%, 95% CI -5·6 to 23·8). The per-protocol analysis suggested non-inferiority of AQ-13 to artemether plus lumefantrine. By contrast, the intention-to-treat analysis, which included two participants who withdrew and three who were lost to follow-up from the AQ-13 group, did not meet the criterion for non-inferiority of AQ-13, although there were no AQ-13 treatment failures. Studies with more participants (and non-immune participants) are needed to decide whether widespread use of modified 4-aminoquinolones should be recommended. US Food and Drug Administration Orphan Product Development, National Institutes of Health, US Centers for Disease Control and Prevention, Burroughs-Wellcome Fund, US State Department, and WHO. Copyright © 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.