Muhe, L.; Oljira, B.; Degefu, H.; Enquesellassie, F.; Weber, M.
OBJECTIVES—To assess the proportion of children with febrile disease who suffer from malaria and to identify clinical signs and symptoms that predict malaria during low and high transmission seasons. STUDY DESIGN—2490 children aged 2 to 59 months presenting to a health centre in rural Ethiopia with fever had their history documented and the following investigations: clinical examination, diagnosis, haemoglobin measurement, and a blood smear for malaria parasites. Clinical findings were related to the presence of malaria parasitaemia. RESULTS—Malaria contributed to 5.9% of all febrile cases from January to April and to 30.3% during the rest of the year. Prediction of malaria was improved by simple combinations of a few signs and symptoms. Fever with a history of previous malarial attack or absence of cough or a finding of pallor gave a sensitivity of 83% in the high risk season and 75% in the low risk season, with corresponding specificities of 51% and 60%; fever with a previous malaria attack or pallor or splenomegaly had sensitivities of 80% and 69% and specificities of 65% and 81% in high and low risk settings, respectively. CONCLUSION—Better clinical definitions are possible for low malaria settings when microscopic examination cannot be done. Health workers should be trained to detect pallor and splenomegaly because these two signs improve the specificity for malaria. PMID:10451393
Background There is currently no standard way of defining malaria seasonality, resulting in a wide range of definitions reported in the literature. Malaria cases show seasonal peaks in most endemic settings, and the choice and timing for optimal malaria control may vary by seasonality. A simple approach is presented to describe the seasonality of malaria, to aid localized policymaking and targeting of interventions. Methods A series of systematic literature reviews were undertaken to identify studies reporting on monthly data for full calendar years on clinical malaria, hospital admission with malaria and entomological inoculation rates (EIR). Sites were defined as having 'marked seasonality' if 75% or more of all episodes occurred in six or less months of the year. A 'concentrated period of malaria' was defined as the six consecutive months with the highest cumulative proportion of cases. A sensitivity analysis was performed based on a variety of cut-offs. Results Monthly data for full calendar years on clinical malaria, all hospital admissions with malaria, and entomological inoculation rates were available for 13, 18, and 11 sites respectively. Most sites showed year-round transmission with seasonal peaks for both clinical malaria and hospital admissions with malaria, with a few sites fitting the definition of 'marked seasonality'. For these sites, consistent results were observed when more than one outcome or more than one calendar year was available from the same site. The use of monthly EIR data was found to be of limited value when looking at seasonal variations of malaria transmission, particularly at low and medium intensity levels. Conclusion The proposed definition discriminated well between studies with 'marked seasonality' and those with less seasonality. However, a poor fit was observed in sites with two seasonal peaks. Further work is needed to explore the applicability of this definition on a wide-scale, using routine health information system data
Adomako-Ankomah, Yaw; Chenoweth, Matthew S.; Durfee, Katelyn; Doumbia, Saibou; Konate, Drissa; Doumbouya, Mory; Keita, Abdoul S.; Nikolaeva, Daria; Tullo, Gregory S.; Anderson, Jennifer M.; Fairhurst, Rick M.; Daniels, Rachel; Volkman, Sarah K.; Diakite, Mahamadou; Long, Carole A.
The effects of persistent Plasmodium falciparum (Pf) infection and multiclonality on subsequent risk of clinical malaria have been reported, but the relationship between these 2 parameters and their relative impacts on the clinical outcome of infection are not understood. A longitudinal cohort study was conducted in a seasonal and high-transmission area of Mali, in which 500 subjects aged 1–65 years were followed for 1 year. Blood samples were collected every 2 weeks, and incident malaria cases were diagnosed and treated. Pf infection in each individual at each time point was assessed by species-specific nested-PCR, and Pf longitudinal prevalence per person (PfLP, proportion of Pf-positive samples over 1 year) was calculated. Multiclonality of Pf infection was measured using a 24-SNP DNA barcoding assay at 4 time-points (two in wet season, and two in dry season) over one year. PfLP was positively correlated with multiclonality at each time point (all r≥0.36; all P≤0.011). When host factors (e.g., age, gender), PfLP, and multiclonality (at the beginning of the transmission season) were analyzed together, only increasing age and high PfLP were associated with reduced clinical malaria occurrence or reduced number of malaria episodes (for both outcomes, P<0.001 for age, and P = 0.005 for PfLP). When age, PfLP and baseline Pf positivity were analyzed together, the effect of high PfLP remained significant even after adjusting for the other two factors (P = 0.001 for malaria occurrence and P<0.001 for number of episodes). In addition to host age and baseline Pf positivity, both of which have been reported as important modifiers of clinical malaria risk, our results demonstrate that persistent parasite carriage, but not baseline multiclonality, is associated with reduced risk of clinical disease in this population. Our study emphasizes the importance of considering repeated parasite exposure in future studies that evaluate clinical malaria risk. PMID:28158202
Adomako-Ankomah, Yaw; Chenoweth, Matthew S; Durfee, Katelyn; Doumbia, Saibou; Konate, Drissa; Doumbouya, Mory; Keita, Abdoul S; Nikolaeva, Daria; Tullo, Gregory S; Anderson, Jennifer M; Fairhurst, Rick M; Daniels, Rachel; Volkman, Sarah K; Diakite, Mahamadou; Miura, Kazutoyo; Long, Carole A
The effects of persistent Plasmodium falciparum (Pf) infection and multiclonality on subsequent risk of clinical malaria have been reported, but the relationship between these 2 parameters and their relative impacts on the clinical outcome of infection are not understood. A longitudinal cohort study was conducted in a seasonal and high-transmission area of Mali, in which 500 subjects aged 1-65 years were followed for 1 year. Blood samples were collected every 2 weeks, and incident malaria cases were diagnosed and treated. Pf infection in each individual at each time point was assessed by species-specific nested-PCR, and Pf longitudinal prevalence per person (PfLP, proportion of Pf-positive samples over 1 year) was calculated. Multiclonality of Pf infection was measured using a 24-SNP DNA barcoding assay at 4 time-points (two in wet season, and two in dry season) over one year. PfLP was positively correlated with multiclonality at each time point (all r≥0.36; all P≤0.011). When host factors (e.g., age, gender), PfLP, and multiclonality (at the beginning of the transmission season) were analyzed together, only increasing age and high PfLP were associated with reduced clinical malaria occurrence or reduced number of malaria episodes (for both outcomes, P<0.001 for age, and P = 0.005 for PfLP). When age, PfLP and baseline Pf positivity were analyzed together, the effect of high PfLP remained significant even after adjusting for the other two factors (P = 0.001 for malaria occurrence and P<0.001 for number of episodes). In addition to host age and baseline Pf positivity, both of which have been reported as important modifiers of clinical malaria risk, our results demonstrate that persistent parasite carriage, but not baseline multiclonality, is associated with reduced risk of clinical disease in this population. Our study emphasizes the importance of considering repeated parasite exposure in future studies that evaluate clinical malaria risk.
MacLeod, D. A.; Morse, A. P.
Around $1.6 billion per year is spent financing anti-malaria initiatives, and though malaria morbidity is falling, the impact of annual epidemics remains significant. Whilst malaria risk may increase with climate change, projections are highly uncertain and to sidestep this intractable uncertainty, adaptation efforts should improve societal ability to anticipate and mitigate individual events. Anticipation of climate-related events is made possible by seasonal climate forecasting, from which warnings of anomalous seasonal average temperature and rainfall, months in advance are possible. Seasonal climate hindcasts have been used to drive climate-based models for malaria, showing significant skill for observed malaria incidence. However, the relationship between seasonal average climate and malaria risk remains unquantified. Here we explore this relationship, using a dynamic weather-driven malaria model. We also quantify key uncertainty in the malaria model, by introducing variability in one of the first order uncertainties in model formulation. Results are visualized as location-specific impact surfaces: easily integrated with ensemble seasonal climate forecasts, and intuitively communicating quantified uncertainty. Methods are demonstrated for two epidemic regions, and are not limited to malaria modeling; the visualization method could be applied to any climate impact.
MacLeod, D. A.; Morse, A. P.
Around $1.6 billion per year is spent financing anti-malaria initiatives, and though malaria morbidity is falling, the impact of annual epidemics remains significant. Whilst malaria risk may increase with climate change, projections are highly uncertain and to sidestep this intractable uncertainty, adaptation efforts should improve societal ability to anticipate and mitigate individual events. Anticipation of climate-related events is made possible by seasonal climate forecasting, from which warnings of anomalous seasonal average temperature and rainfall, months in advance are possible. Seasonal climate hindcasts have been used to drive climate-based models for malaria, showing significant skill for observed malaria incidence. However, the relationship between seasonal average climate and malaria risk remains unquantified. Here we explore this relationship, using a dynamic weather-driven malaria model. We also quantify key uncertainty in the malaria model, by introducing variability in one of the first order uncertainties in model formulation. Results are visualized as location-specific impact surfaces: easily integrated with ensemble seasonal climate forecasts, and intuitively communicating quantified uncertainty. Methods are demonstrated for two epidemic regions, and are not limited to malaria modeling; the visualization method could be applied to any climate impact. PMID:25449318
MacLeod, D A; Morse, A P
Around $1.6 billion per year is spent financing anti-malaria initiatives, and though malaria morbidity is falling, the impact of annual epidemics remains significant. Whilst malaria risk may increase with climate change, projections are highly uncertain and to sidestep this intractable uncertainty, adaptation efforts should improve societal ability to anticipate and mitigate individual events. Anticipation of climate-related events is made possible by seasonal climate forecasting, from which warnings of anomalous seasonal average temperature and rainfall, months in advance are possible. Seasonal climate hindcasts have been used to drive climate-based models for malaria, showing significant skill for observed malaria incidence. However, the relationship between seasonal average climate and malaria risk remains unquantified. Here we explore this relationship, using a dynamic weather-driven malaria model. We also quantify key uncertainty in the malaria model, by introducing variability in one of the first order uncertainties in model formulation. Results are visualized as location-specific impact surfaces: easily integrated with ensemble seasonal climate forecasts, and intuitively communicating quantified uncertainty. Methods are demonstrated for two epidemic regions, and are not limited to malaria modeling; the visualization method could be applied to any climate impact.
Merkord, C. L.; Wimberly, M. C.; Henebry, G. M.; Senay, G. B.
Malaria is a major public health problem throughout tropical regions of the world. Successful prevention and treatment of malaria requires an understanding of the environmental factors that affect the life cycle of both the malaria pathogens, protozoan parasites, and its vectors, anopheline mosquitos. Because the egg, larval, and pupal stages of mosquito development occur in aquatic habitats, information about the spatial and temporal distribution of rainfall is critical for modeling malaria risk. Potential sources of hydrological data include satellite-derived rainfall estimates (TRMM and GPM), evapotranspiration derived from a simplified surface energy balance, and estimates of soil moisture and fractional water cover from passive microwave imagery. Previous studies have found links between malaria cases and total monthly or weekly rainfall in areas where both are highly seasonal. However it is far from clear that monthly or weekly summaries are the best metrics to use to explain malaria outbreaks. It is possible that particular temporal or spatial patterns of rainfall result in better mosquito habitat and thus higher malaria risk. We used malaria case data from the Amhara region of Ethiopia and satellite-derived rainfall estimates to explore the relationship between malaria outbreaks and rainfall with the goal of identifying the most useful rainfall metrics for modeling malaria occurrence. First, we explored spatial variation in the seasonal patterns of both rainfall and malaria cases in Amhara. Second, we assessed the relative importance of different metrics of rainfall intermittency, including alternation of wet and dry spells, the strength of intensity fluctuations, and spatial variability in these measures, in determining the length and severity of malaria outbreaks. We also explored the sensitivity of our results to the choice of method for describing rainfall intermittency and the spatial and temporal scale at which metrics were calculated. Results
Syafruddin, Din; Krisin; Asih, Puji; Sekartuti; Dewi, Rita M; Coutrier, Farah; Rozy, Ismail E; Susanti, Augustina I; Elyazar, Iqbal RF; Sutamihardja, Awalludin; Rahmat, Agus; Kinzer, Michael; Rogers, William O
Background Accurate information about the burden of malaria infection at the district or provincial level is required both to plan and assess local malaria control efforts. Although many studies of malaria epidemiology, immunology, and drug resistance have been conducted at many sites in Indonesia, there is little published literature describing malaria prevalence at the district, provincial, or national level. Methods Two stage cluster sampling malaria prevalence surveys were conducted in the wet season and dry season across West Sumba, Nusa Tenggara Province, Indonesia. Results Eight thousand eight hundred seventy samples were collected from 45 sub-villages in the surveys. The overall prevalence of malaria infection in the West Sumba District was 6.83% (95% CI, 4.40, 9.26) in the wet season and 4.95% (95% CI, 3.01, 6.90) in the dry. In the wet season Plasmodium falciparum accounted for 70% of infections; in the dry season P. falciparum and Plasmodium vivax were present in equal proportion. Malaria prevalence varied substantially across the district; prevalences in individual sub-villages ranged from 0–34%. The greatest malaria prevalence was in children and teenagers; the geometric mean parasitaemia in infected individuals decreased with age. Malaria infection was clearly associated with decreased haemoglobin concentration in children under 10 years of age, but it is not clear whether this association is causal. Conclusion Malaria is hypoendemic to mesoendemic in West Sumba, Indonesia. The age distribution of parasitaemia suggests that transmission has been stable enough to induce some clinical immunity. These prevalence data will aid the design of future malaria control efforts and will serve as a baseline against which the results of current and future control efforts can be assessed. PMID:19134197
Seasonal total precipitation is well known to affect malaria transmission because Anopheles mosquitoes depend on standing water for breeding habitat. However, the within-season temporal pattern of the rainfall influences persistence of standing water and thus rainfall patterns also affect mosquito population dynamics. In this talk, I show that intraseasonal rainfall pattern describes 40% of the variance in simulated mosquito abundance in a Niger Sahel village where malaria is endemic but highly seasonal, demonstrating the necessity for detailed distributed hydrology modeling to explain the variance from this important effect. I apply a field validated, high spatial- and temporal-resolution hydrology model coupled with an entomology model. Using synthetic rainfall time series generated using a stationary first-order Markov Chain model, I hold all variables except hourly rainfall constant, thus isolating the contribution of rainfall pattern to variance in mosquito abundance. I further show the utility of hydrology modeling to assess precipitation effects by analyzing collected water. Time-integrated surface area of pools explains 70% of the variance in mosquito abundance, and time-integrated surface area of pools persisting longer than seven days explains 82% of the variance, showing an improved predictive ability when pool persistence is explicitly modeled at high spatio-temporal resolution. I extend this analysis to investigate the impacts of this effect on malaria vector mosquito populations under climate shift scenarios, holding all climate variables except precipitation constant. In these scenarios, rainfall mean and variance change with climatic change, and the modeling approach evaluates the impact of non-stationarity in rainfall and the associated rainfall patterns on expected mosquito activity.
Background Few data are available about malaria epidemiological situation in Niger. However, implementation of new strategies such as vaccination or seasonal treatment of a target population requires the knowledge of baseline epidemiological features of malaria. A population-based study was conducted to provide better characterization of malaria seasonal variations and population groups the most at risk in this particular area. Methods From July 2007 to December 2009, presumptive cases of malaria among a study population living in a typical Sahelian village of Niger were recorded, and confirmed by microscopic examination. In parallel, asymptomatic carriers were actively detected at the end of each dry season in 2007, 2008 and 2009. Results Among the 965 presumptive malaria cases recorded, 29% were confirmed by microscopic examination. The incidence of malaria was found to decrease significantly with age (p < 0.01). The mean annual incidence was 0.254. The results show that the risk of malaria was higher in children under ten years (p < 0.0001). The number of malaria episodes generally followed the temporal pattern of changes in precipitation levels, with a peak of transmission in August and September. One-thousand and ninety subjects were submitted to an active detection of asymptomatic carriage of whom 16% tested positive; asymptomatic carriage decreased with increasing age. A higher prevalence of gametocyte carriage among asymptomatic population was recorded in children aged two to ten years, though it did not reach significance. Conclusions In Southern Niger, malaria transmission mostly occurs from July to October. Children aged two to ten years are the most at risk of malaria, and may also represent the main reservoir for gametocytes. Strategies such as intermittent preventive treatment in children (IPTc) could be of interest in this area, where malaria transmission is highly seasonal. Based on these preliminary data, a pilot study could be implemented
Background Until recently the Chittagong Hill tracts have been hyperendemic for malaria. A past cross-sectional RDT based survey in 2007 recorded rates of approximately 15%. This study was designed to understand the present epidemiology of malaria in this region, to monitor and facilitate the uptake of malaria intervention activities of the national malaria programme and to serve as an area for developing new and innovative control strategies for malaria. Methods This research field area was established in two rural unions of Bandarban District of Bangladesh north of Bandarban city, which are known to be endemic for malaria due to Plasmodium falciparum. The project included the following elements: a) a demographic surveillance system including an initial census with updates every four months, b) periodic surveys of knowledge attitude and practice, c) a geographic information system, d) weekly active and continuous passive surveillance for malaria infections using smears, rapid tests and PCR, f) monthly mosquito surveillance, and e) daily weather measures. The programme included both traditional and molecular methods for detecting malaria as well as lab methods for speciating mosquitoes and detecting mosquitoes infected with sporozoites. Results The demographic surveillance enumerated and mapped 20,563 people, 75% of which were tribal non-Bengali. The monthly mosquito surveys identified 22 Anopheles species, eight of which were positive by circumsporozoite ELISA. The annual rate of malaria was close to 1% with 85% of cases in the rainy months of May-October. Definitive clustering identified in the low transmission season persisted during the high transmission season. Conclusion This demographically and geographically defined area, near to the Myanmar border, which is also hypoendemic for malaria, will be useful for future studies of the epidemiology of malaria and for evaluation of strategies for malaria control including new drugs and vaccines. PMID:21569599
Diouf, Ibrahima; Rodríguez de Fonseca, Belen; Deme, Abdoulaye; Cisse Cisse, Moustapha; Ndione Ndione, Jaques-Andre; Gaye, Amadou T.; Suarez, Roberto
Beyond assessment and analysis of observed and simulated malaria parameters, this study is furthermore undertaken in the framework of predictability of malaria outbreaks in Senegal and remote regions in Sahel, which are found to take place two months after the rainy season. The predictors are the sea surface temperature anomalous patterns at different ocean basins mainly over the Pacific and Atlantic as they are related to changes in air temperature, humidity, rainfall and wind. A relationship between El Niño and anomalous malaria parameters is found. The malaria parameters are calculated with the Liverpool Malaria Model (LMM) using meteorological datasets from different reanalysis products. A hindcast of these parameters is performed using the Sea Surface temperature based Statistical Seasonal ForeCAST (S4CAST) model developed at UCM in order to predict malaria parameters some months in advance. The results of this work will be useful for decision makers to better access to climate forecasts and application on malaria transmission risk.
Armitage, Andrew E.; Khandwala, Shivani; Mwangi, Tabitha W.; Uyoga, Sophie; Bejon, Philip A.; Williams, Thomas N.; Prentice, Andrew M.; Drakesmith, Hal
Hepcidin is the master regulatory hormone that governs iron homeostasis and has a role in innate immunity. Although hepcidin has been studied extensively in model systems, there is less information on hepcidin regulation in global health contexts where iron deficiency (ID), anemia, and high infectious burdens (including malaria) all coexist but fluctuate over time. We evaluated iron status, hepcidin levels, and determinants of hepcidin in 2 populations of rural children aged ≤8 years, in the Gambia and Kenya (total n = 848), at the start and end of a malaria season. Regression analyses and structural equation modeling demonstrated, for both populations, similar combinatorial effects of upregulating stimuli (iron stores and to a lesser extent inflammation) and downregulating stimuli (erythropoietic drive) on hepcidin levels. However, malaria season was also a significant factor and was associated with an altered balance of these opposing factors. Consistent with these changes, hepcidin levels were reduced whereas the prevalence of ID was increased at the end of the malaria season. More prevalent ID and lower hepcidin likely reflect an enhanced requirement for iron and an ability to efficiently absorb it at the end of the malaria season. These results, therefore, have implications for ID and malaria control programs. PMID:24596418
Atkinson, Sarah H; Armitage, Andrew E; Khandwala, Shivani; Mwangi, Tabitha W; Uyoga, Sophie; Bejon, Philip A; Williams, Thomas N; Prentice, Andrew M; Drakesmith, Hal
Hepcidin is the master regulatory hormone that governs iron homeostasis and has a role in innate immunity. Although hepcidin has been studied extensively in model systems, there is less information on hepcidin regulation in global health contexts where iron deficiency (ID), anemia, and high infectious burdens (including malaria) all coexist but fluctuate over time. We evaluated iron status, hepcidin levels, and determinants of hepcidin in 2 populations of rural children aged ≤8 years, in the Gambia and Kenya (total n = 848), at the start and end of a malaria season. Regression analyses and structural equation modeling demonstrated, for both populations, similar combinatorial effects of upregulating stimuli (iron stores and to a lesser extent inflammation) and downregulating stimuli (erythropoietic drive) on hepcidin levels. However, malaria season was also a significant factor and was associated with an altered balance of these opposing factors. Consistent with these changes, hepcidin levels were reduced whereas the prevalence of ID was increased at the end of the malaria season. More prevalent ID and lower hepcidin likely reflect an enhanced requirement for iron and an ability to efficiently absorb it at the end of the malaria season. These results, therefore, have implications for ID and malaria control programs.
Siraj, Amir S.; Bouma, Menno J.; Santos-Vega, Mauricio; Yeshiwondim, Asnakew K.; Rothman, Dale S.; Yadeta, Damtew; Sutton, Paul C.; Pascual, Mercedes
A better understanding of malaria persistence in highly seasonal environments such as highlands and desert fringes requires identifying the factors behind the spatial reservoir of the pathogen in the low season. In these ‘unstable’ malaria regions, such reservoirs play a critical role by allowing persistence during the low transmission season and therefore, between seasonal outbreaks. In the highlands of East Africa, the most populated epidemic regions in Africa, temperature is expected to be intimately connected to where in space the disease is able to persist because of pronounced altitudinal gradients. Here, we explore other environmental and demographic factors that may contribute to malaria's highland reservoir. We use an extensive spatio-temporal dataset of confirmed monthly Plasmodium falciparum cases from 1995 to 2005 that finely resolves space in an Ethiopian highland. With a Bayesian approach for parameter estimation and a generalized linear mixed model that includes a spatially structured random effect, we demonstrate that population density is important to disease persistence during the low transmission season. This population effect is not accounted for in typical models for the transmission dynamics of the disease, but is consistent in part with a more complex functional form of the force of infection proposed by theory for vector-borne infections, only during the low season as we discuss. As malaria risk usually decreases in more urban environments with increased human densities, the opposite counterintuitive finding identifies novel control targets during the low transmission season in African highlands. PMID:26631558
Siraj, Amir S; Bouma, Menno J; Santos-Vega, Mauricio; Yeshiwondim, Asnakew K; Rothman, Dale S; Yadeta, Damtew; Sutton, Paul C; Pascual, Mercedes
A better understanding of malaria persistence in highly seasonal environments such as highlands and desert fringes requires identifying the factors behind the spatial reservoir of the pathogen in the low season. In these 'unstable' malaria regions, such reservoirs play a critical role by allowing persistence during the low transmission season and therefore, between seasonal outbreaks. In the highlands of East Africa, the most populated epidemic regions in Africa, temperature is expected to be intimately connected to where in space the disease is able to persist because of pronounced altitudinal gradients. Here, we explore other environmental and demographic factors that may contribute to malaria's highland reservoir. We use an extensive spatio-temporal dataset of confirmed monthly Plasmodium falciparum cases from 1995 to 2005 that finely resolves space in an Ethiopian highland. With a Bayesian approach for parameter estimation and a generalized linear mixed model that includes a spatially structured random effect, we demonstrate that population density is important to disease persistence during the low transmission season. This population effect is not accounted for in typical models for the transmission dynamics of the disease, but is consistent in part with a more complex functional form of the force of infection proposed by theory for vector-borne infections, only during the low season as we discuss. As malaria risk usually decreases in more urban environments with increased human densities, the opposite counterintuitive finding identifies novel control targets during the low transmission season in African highlands.
Background Anopheles darlingi is the main malaria mosquito vector in the Amazonia region. In spite of being considered a riverine, forest-dwelling species, this mosquito is becoming more abundant in peri-urban areas, increasing malaria risk. This has been associated with human-driven environmental changes such as deforestation. Methods Microsatellites were used to characterize A. darlingi from seven localities along the Madeira River, Rondônia (Brazil), collected in the early and late periods of the rainy season. Results Two genetically distinct subpopulations were detected: one (subpopulation A) was associated with the late rainfall period and seems to be ecologically closer to the typical forest A. darlingi; the other (subpopulation B) was associated with the early rainfall period and is probably more adapted to drier conditions by exploiting permanent anthropogenic breeding sites. Results suggest also a pattern of asymmetric introgression, with more subpopulation A alleles introgressed into subpopulation B. Both subpopulations (and admixed mosquitoes) presented similar malaria infection rates, highlighting the potential for perennial malaria transmission in the region. Conclusions The co-occurrence of two genetically distinct subpopulations of A. darlingi adapted to different periods of rainfall may promote a more perennial transmission of malaria throughout the year. These findings, in a context of strong environmental impact due to deforestation and dam construction, have serious implications for malaria epidemiology and control in the Amazonian region. PMID:24885508
Malik, Elfatih Mohamed; Hanafi, Kamal; Ali, Salah Hussein; Ahmed, Eldirdieri Salim; Mohamed, Khalid Awad
Background Effective management of malaria in children under the age of 5 requires mothers to seek, obtain, and use medication appropriately. This is linked to timely decision, accessibility, correct use of the drugs and follow-up. The aim of the study is to identify the basis on which fever was recognized and classified and exploring factors involved in selection of different treatment options. Methods Data was obtained by interviewing 96 mothers who had brought their febrile children to selected health facilities, conduction of 10 focus group discussions with mothers at village level as well as by observation. Results A high score of mothers' knowledge and recognition of fever/malaria was recorded. Mothers usually start care at home and, within an average of three days, they shift to health workers if there was no response. The main health-seeking behaviour is to consult the nearest health facility or health personnel together with using traditional medicine or herbs. There are also health workers who visit patients at home. The majority of mothers with febrile children reported taking drugs before visiting a health facility. The choice between the available options determined by the availability of health facilities, user fees, satisfaction with services, difficulty to reach the facilities and believe in traditional medicine. Conclusion Mothers usually go through different treatment option before consulting health facilities ending with obvious delay in seeking care. As early effective treatment is the main theme of the control programme, implementation of malaria home management strategy is urgently needed to improve the ongoing practice. PMID:16859565
Suh, Kathryn N.; Kain, Kevin C.; Keystone, Jay S.
Malaria is a parasitic infection of global importance. Although relatively uncommon in developed countries, where the disease occurs mainly in travellers who have returned from endemic regions, it remains one of the most prevalent infections of humans worldwide. In endemic regions, malaria is a significant cause of morbidity and mortality and creates enormous social and economic burdens. Current efforts to control malaria focus on reducing attributable morbidity and mortality. Targeted chemoprophylaxis and use of insecticide-treated bed nets have been successful in some endemic areas. For travellers to malaria-endemic regions, personal protective measures and appropriate chemoprophylaxis can significantly reduce the risk of infection. Prompt evaluation of the febrile traveller, a high degree of suspicion of malaria, rapid and accurate diagnosis, and appropriate antimalarial therapy are essential in order to optimize clinical outcomes of infected patients. Additional approaches to malaria control, including genetic manipulation of mosquitoes and malaria vaccines, are areas of ongoing research. PMID:15159369
MacLeod, Dave A.; Jones, Anne; Di Giuseppe, Francesca; Caminade, Cyril; Morse, Andrew P.
The severity and timing of seasonal malaria epidemics is strongly linked with temperature and rainfall. Advance warning of meteorological conditions from seasonal climate models can therefore potentially anticipate unusually strong epidemic events, building resilience and adapting to possible changes in the frequency of such events. Here we present validation of a process-based, dynamic malaria model driven by hindcasts from a state-of-the-art seasonal climate model from the European Centre for Medium-Range Weather Forecasts. We validate the climate and malaria models against observed meteorological and incidence data for Botswana over the period 1982-2006 the longest record of observed incidence data which has been used to validate a modeling system of this kind. We consider the impact of climate model biases, the relationship between climate and epidemiological predictability and the potential for skillful malaria forecasts. Forecast skill is demonstrated for upper tercile malaria incidence for the Botswana malaria season (January-May), using forecasts issued at the start of November; the forecast system anticipates six out of the seven upper tercile malaria seasons in the observational period. The length of the validation time series gives confidence in the conclusion that it is possible to make reliable forecasts of seasonal malaria risk, forming a key part of a health early warning system for Botswana and contributing to efforts to adapt to climate change.
Griffin, Jamie T
The basic reproduction number (R0) is an important quantity summarising the dynamics of an infectious disease, as it quantifies how much effort is needed to control transmission. The relative change in R0 due to an intervention is referred to as the effect size. However malaria and other diseases are often highly seasonal and some interventions have time-varying effects, meaning that simple reproduction number formulae cannot be used. Methods have recently been developed for calculating R0 for diseases with seasonally varying transmission. I extend those methods to calculate the effect size of repeated rounds of mass drug administration, indoor residual spraying and other interventions against Plasmodium falciparum malaria in seasonal settings in Africa. I show that if an intervention reduces transmission from one host to another by a constant factor, then its effect size is the same in a seasonal as in a non-seasonal setting. The optimal time of year for drug administration is in the low season, whereas the best time for indoor residual spraying or a vaccine which reduces infection rates is just before the high season. In general, the impact of time-varying interventions increases with increasing seasonality, if carried out at the optimal time of year. The effect of combinations of interventions that act at different stages of the transmission cycle is roughly the product of the separate effects. However for individual time-varying interventions, it is necessary to use methods such as those developed here rather than inserting the average efficacy into a simple formula.
Moise, Imelda K; Sen Roy, Shouraseni; Nkengurutse, Delphin; Ndikubagenzi, Jacques
We analyzed hospitalization records from 2011 to 2012 to examine the spatial patterns of pediatric malaria in Burundi. Malaria case data for those below the age of five years were categorized according to the four principal seasons of Burundi, which are two rainy seasons (February to May; September to November) and two dry seasons (June to August; December to January). The Getis-Ord Gi* statistic was used to examine seasonal spatial patterns of pediatric malaria, whereas geographically weighted regression (GWR) were used to examine the potential role of environmental variables on the spatial patterns of cases. There were a total of 19,890 pediatric malaria cases reported during the study period. The incidence among males was higher than that among females; and it was higher in rural districts. The seasonal incidence peaks occurred in the northern half of the country during the wet season while during the dry season, incidence was higher in southern Burundi. Elevation played a greater role in explaining variance in the prevalence of pediatric malaria during seasonal peaks than rainfall. The counterintuitive finding in northern Burundi confirms previous findings and suggests other factors (e.g., land cover/land use) facilitate the persistence of the mosquito population in the highlands of Africa.
Moise, Imelda K.; Roy, Shouraseni Sen; Nkengurutse, Delphin; Ndikubagenzi, Jacques
We analyzed hospitalization records from 2011 to 2012 to examine the spatial patterns of pediatric malaria in Burundi. Malaria case data for those below the age of five years were categorized according to the four principal seasons of Burundi, which are two rainy seasons (February to May; September to November) and two dry seasons (June to August; December to January). The Getis-Ord Gi* statistic was used to examine seasonal spatial patterns of pediatric malaria, whereas geographically weighted regression (GWR) were used to examine the potential role of environmental variables on the spatial patterns of cases. There were a total of 19,890 pediatric malaria cases reported during the study period. The incidence among males was higher than that among females; and it was higher in rural districts. The seasonal incidence peaks occurred in the northern half of the country during the wet season while during the dry season, incidence was higher in southern Burundi. Elevation played a greater role in explaining variance in the prevalence of pediatric malaria during seasonal peaks than rainfall. The counterintuitive finding in northern Burundi confirms previous findings and suggests other factors (e.g., land cover/land use) facilitate the persistence of the mosquito population in the highlands of Africa. PMID:27092518
Diouf, Ibrahima; Deme, Abdoulaye; Rodriguez-Fonseca, Belen; Suárez-Moreno, Roberto; Cisse, Moustapha; Ndione, Jacques-André; Thierno Gaye, Amadou
Senegal and, in general, West African regions are affected by important outbreaks of diseases with destructive consequences for human population, livestock and country's economy. The vector-borne diseases such as mainly malaria, Rift Valley Fever and dengue are affected by the interanual to decadal variability of climate. Analysis of the spatial and temporal variability of climate parameters and associated oceanic patterns is important in order to assess the climate impact on malaria transmission. In this study, the approach developed to study the malaria-climate link is predefined by the QWeCI project (Quantifying Weather and Climate Impacts on Health in Developing Countries). Preliminary observations and simulations results over Senegal Ferlo region, confirm that the risk of malaria transmission is mainly linked to climate parameters such as rainfall, temperature and relative humidity; and a lag of one to two months between the maximum of malaria and the maximum of climate parameters as rainfall is observed. As climate variables are able to be predicted from oceanic SST variability in remote regions, this study explores seasonal predictability of malaria incidence outbreaks from previous sea surface temperatures conditions in different ocean basins. We have found causal or coincident relationship between El Niño and malaria parameters by coupling LMM UNILIV malaria model and S4CAST statistiscal model with the aim of predicting the malaria parameters with more than 6 months in advance. In particular, El Niño is linked to an important decrease of the number of mosquitoes and the malaria incidence. Results from this research, after assessing the seasonal malaria parameters, are expected to be useful for decision makers to better access to climate forecasts and application on health in the framework of rolling back malaria transmission.
Stuckey, Erin M; Smith, Thomas; Chitnis, Nakul
Evaluating the effectiveness of malaria control interventions on the basis of their impact on transmission as well as impact on morbidity and mortality is becoming increasingly important as countries consider pre-elimination and elimination as well as disease control. Data on prevalence and transmission are traditionally obtained through resource-intensive epidemiological and entomological surveys that become difficult as transmission decreases. This work employs mathematical modeling to examine the relationships between malaria indicators allowing more easily measured data, such as routine health systems data on case incidence, to be translated into measures of transmission and other malaria indicators. Simulations of scenarios with different levels of malaria transmission, patterns of seasonality and access to treatment were run with an ensemble of models of malaria epidemiology and within-host dynamics, as part of the OpenMalaria modeling platform. For a given seasonality profile, regression analysis mapped simulation results of malaria indicators, such as annual average entomological inoculation rate, prevalence, incidence of uncomplicated and severe episodes, and mortality, to an expected range of values of any of the other indicators. Results were validated by comparing simulated relationships between indicators with previously published data on these same indicators as observed in malaria endemic areas. These results allow for direct comparisons of malaria transmission intensity estimates made using data collected with different methods on different indicators. They also address key concerns with traditional methods of quantifying transmission in areas of differing transmission intensity and sparse data. Although seasonality of transmission is often ignored in data compilations, the models suggest it can be critically important in determining the relationship between transmission and disease. Application of these models could help public health officials
Background Reservoirs created by damming rivers are often believed to increase malaria incidence risk and/or stretch the period of malaria transmission. In this paper, we report the effects of a mega hydropower dam on P. falciparum malaria incidence in Ethiopia. Methods A longitudinal cohort study was conducted over a period of 2 years to determine Plasmodium falciparum malaria incidence among children less than 10 years of age living near a mega hydropower dam in Ethiopia. A total of 2080 children from 16 villages located at different distances from a hydropower dam were followed up from 2008 to 2010 using active detection of cases based on weekly house to house visits. Of this cohort of children, 951 (48.09%) were females and 1059 (51.91%) were males, with a median age of 5 years. Malaria vectors were simultaneously surveyed in all the 16 study villages. Frailty models were used to explore associations between time-to-malaria and potential risk factors, whereas, mixed-effects Poisson regression models were used to assess the effect of different covariates on anopheline abundance. Results Overall, 548 (26.86%) children experienced at least one clinical malaria episode during the follow up period with mean incidence rate of 14.26 cases/1000 child-months at risk (95% CI: 12.16 - 16.36). P. falciparum malaria incidence showed no statistically significant association with distance from the dam reservoir (p = 0.32). However, P. falciparum incidence varied significantly between seasons (p < 0.01). The malaria vector, Anopheles arabiensis, was however more abundant in villages nearer to the dam reservoir. Conclusions P. falciparum malaria incidence dynamics were more influenced by seasonal drivers than by the dam reservoir itself. The findings could have implications in timing optimal malaria control interventions and in developing an early warning system in Ethiopia. PMID:23566411
Smeeth, Liam; Cruickshank, J. Kennedy; Scott, J. Anthony G.
Rationale: Several studies have demonstrated links between infectious diseases and cardiovascular conditions. Malaria and hypertension are widespread in many low- and middle-income countries, but the possible link between them has not been considered. Objective: In this article, we outline the basis for a possible link between malaria and hypertension and discuss how the hypothesis could be confirmed or refuted. Methods and Results: We reviewed published literature on factors associated with hypertension and checked whether any of these were also associated with malaria. We then considered various study designs that could be used to test the hypothesis. Malaria causes low birth weight, malnutrition, and inflammation, all of which are associated with hypertension in high-income countries. The hypothetical link between malaria and hypertension can be tested through the use of ecological, cohort, or Mendelian randomization studies, each of which poses specific challenges. Conclusions: Confirmation of the existence of a causative link with malaria would be a paradigm shift in efforts to prevent and control hypertension and would stimulate wider research on the links between infectious and noncommunicable disease. PMID:27151400
Background Malaria control interventions have been scaled-up in Zambia in conjunction with a malaria surveillance system. Although substantial progress has been achieved in reducing morbidity and mortality, national and local information demonstrated marked heterogeneity in the impact of malaria control across the country. This study reports the high burden of malaria in Nchelenge District, Luapula Province, Zambia from 2006 to 2012 after seven years of control measures. Methods Yearly aggregated information on cases of malaria, malaria deaths, use of malaria diagnostics, and malaria control interventions from 2006 to 2012 were obtained from the Nchelenge District Health Office. Trends in the number of malaria cases, methods of diagnosis, malaria positivity rate among pregnant women, and intervention coverage were analysed using descriptive statistics. Results Malaria prevalence remained high, increasing from 38% in 2006 to 53% in 2012. Increasing numbers of cases of severe malaria were reported until 2010. Intense seasonal malaria transmission was observed with seasonal declines in the number of cases between April and August, although malaria transmission continued throughout the year. Clinical diagnosis without accompanying confirmation declined from 95% in 2006 to 35% in 2012. Intervention coverage with long-lasting insecticide-treated nets and indoor residual spraying increased from 2006 to 2012. Conclusions Despite high coverage with vector control interventions, the burden of malaria in Nchelenge District, Zambia remained high. The high parasite prevalence could accurately reflect the true burden, perhaps in part as a consequence of population movement, or improved access to care and case reporting. Quality information at fine spatial scales will be critical for targeting effective interventions and measurement of progress. PMID:24755108
Hu, Yue; Zhou, Guofa; Ruan, Yonghua; Lee, Ming-chieh; Xu, Xin; Deng, Shuang; Bai, Yao; Zhang, Jie; Morris, James; Liu, Huaie; Wang, Ying; Fan, Qi; Li, Peipei; Wu, Yanrui; Yang, Zhaoqing; Yan, Guiyun; Cui, Liwang
Malaria transmission is heterogeneous in the Greater Mekong Subregion with most of the cases occurring along international borders. Knowledge of transmission hotspots is essential for targeted malaria control and elimination in this region. This study aimed to determine the dynamics of malaria transmission and possible existence of transmission hotspots on a microgeographical scale along the China-Myanmar border. Microscopically confirmed clinical malaria cases were recorded in five border villages through a recently established surveillance system between January 2011 and December 2014. A total of 424 clinical cases with confirmed spatial and temporal information were analyzed, of which 330 (77.8%) were Plasmodium vivax and 88 (20.8%) were Plasmodium falciparum, respectively. The P. vivax and P. falciparum case ratio increased dramatically from 2.2 in 2011 to 4.7 in 2014, demonstrating that P. vivax malaria has become the predominant parasite species. Clinical infections showed a strong bimodal seasonality. There were significant differences in monthly average incidence rates among the study villages with rates in a village in China being 3-8 folds lower than those in nearby villages in Myanmar. Spatial analysis revealed the presence of clinical malaria hotspots in four villages. This information on malaria seasonal dynamics and transmission hotspots should be harnessed for planning targeted control.
Thomas, Bolaji N.; Diallo, Dapa A.; Noumsi, Ghislain T.; Moulds, Joann M.
Complement receptor one (CR1) is essential for removing circulating immune complexes (CIC), with malaria infection contributing to the formation of large amounts of CIC. We investigated CIC levels in children with malaria, of varying severity and seasonality. Two hundred age and sex-matched severe and mild malaria cases were studied during and after active disease. Pediatric controls had increased CIC levels (mean = 32 μg mEq/mL) compared to adult controls (mean = 26.9 μg mEq/mL). The highest levels of CIC were reported in severe malaria (mean = 39 μg mEq/mL). Higher levels of CIC were recorded in younger children and those with low E-CR1 copy numbers. Our data suggest that low levels of E-CR1 copy numbers, found in children with severe malaria, may adversely affect the ability to remove IC. Furthermore, the high background for circulating immune complex imply that Malian children are under constant assault by other pathogens that evoke a strong immune response. PMID:22837639
Heck, J E
Human malaria is caused by four species of the genus plasmodium. The sexual stage of the parasite occurs in the mosquito and asexual reproduction occurs in man. Symptoms of fever, chills, headache, and myalgia result from the invasion and rupture of erythrocytes. Merozoites are released from erythrocytes and invade other cells, thus propagating the infection. The most vulnerable hosts are nonimmune travelers, young children living in the tropics, and pregnant women. P. falciparum causes the most severe infections because it infects RBCs of all ages and has the propensity to develop resistance to antimalarials. Rapid diagnosis can be made with a malarial smear, and treatment should be initiated promptly. In some regions (Mexico, Central America except Panama, and North Africa) chloroquine phosphate is effective therapy. In subsaharan Africa, South America, and Southeast Asia, chloroquine resistance has become widespread, and other antimalarials are necessary. The primary care physician should have a high index of suspicion for malaria in the traveler returning from the tropics. Malaria should also be suspected in the febrile transfusion recipient and newborns of mothers with malaria.
Fuehrer, Hans-Peter; Swoboda, Paul; Harl, Josef; Starzengruber, Peter; Habler, Verena Elisabeth; Bloeschl, Ingrid; Haque, Rashidul; Matt, Julia; Khan, Wasif Ali; Noedl, Harald
Although the prevalence of malaria remains high in parts of Bangladesh, there continues to be a substantial shortage of information regarding the less common malaria parasites such as Plasmodium malariae or Plasmodium knowlesi. Recent studies indicate that P. malariae may be extremely rare, and so far, there are no data on the presence (or absence) of P. knowlesi in southeastern Bangladesh. Genus- and species-specific nested polymerase chain reaction (PCR) analysis of the small subunit ribosomal RNA gene was performed to assess the presence and prevalence of P. malariae and P. knowlesi in 2,246 samples originating from asymptomatic and febrile participants of a cross-sectional and a febrile illnesses study in the Chittagong Hill Tracts in southeastern Bangladesh. P. malariae was detected in 60 samples (2.7%) corresponding to 8% of the 746 samples giving positive PCR results for Plasmodium sp., mainly because of the high prevalence (9.5%) among asymptomatic study participants testing positive for malaria. Symptomatic cases were more common (4.3% of all symptomatic malaria cases) during the dry season. Parasitemias were low (1,120-2,560/μl in symptomatic and 120-520/μl in asymptomatic carriers). Symptomatic patients presented mild to moderate symptoms like fever, chills, headache, dizziness, fatigue and myalgia.Although both the intermediate as well as the definite host are known to be endemic in southeastern Bangladesh, no evidence for the presence of P. knowlesi was found. We conclude that the role of P. malariae is highly underestimated in rural Bangladesh with major implications for malaria control and elimination strategies.
Rahman, Atiqur; Krakauer, Nir; Roytman, Leonid; Goldberg, Mitch; Kogan, Felix
Satellite data may be used to map climatic conditions conducive to malaria outbreaks, assisting in the targeting of public health interventions to mitigate the worldwide increase in incidence of the mosquito-transmitted disease. This work analyzes correlation between malaria cases and vegetation health (VH) indices derived from satellite remote sensing for each week over a period of 14 years for Bandarban, Bangladesh. Correlation analysis showed that years with a high summer temperature condition index (TCI) tended to be those with high malaria incidence. Principal components regression was performed on patterns of weekly TCI during each of the two annual malaria seasons to construct a model as a function of the TCI. These models reduced the malaria estimation error variance by 57% if first-peak (June-July) TCI was used as the estimator and 74% if second-peak (August-September) was used, compared with an estimation of average number of malaria cases for each year.
... common?Malaria is a health problem in many tropical and subtropical countries, including portions of Central and ... these countries. If you are traveling to a tropical area or to a country where malaria is ...
Malaria, the greatest pandemia in the world, claims an estimated one million lives each year in Africa alone. While it may still be said that for the most part malaria is found in what is known as the world's poverty belt, cases are now frequently diagnosed in western countries. Due to resistant strains of malaria which have developed because of…
Basseri, Hamidreza; Raeisi, Ahmad; Ranjbar Khakha, Mansoor; Pakarai, Abaas; Abdolghafar, Hassanzehi
Seasonal abundance and tendency to feed on humans are important parameters to measure for effective control of malaria vectors. The objective of this study was to describe relation between feeding pattern, abundance, and resting behavior of four malaria vectors in southern Iran. This study was conducted in ten indicator villages (based on malaria incidence and entomological indices) in mountainous/hilly and plain regions situated south and southeastern Iran. Mosquito vectors were collected from indoor as well as outdoor shelters and the blood meals were examined by ELISA test. Over all 7654 female Anopheles spp. were captured, the most common species were Anopheles stephensi, An. culicifacies, An. fluviatilis, and An. d'thali. The overall human blood index was 37.50%, 19.83%, 16.4%, and 30.1% for An. fluviatilis, An. stephensi, An. culicifacies, and An. d'thali, respectively. In addition, An. fluviatilis fed on human blood during the entire year but the feeding behavior of An. stephensi and An. culicifacies varied according to seasons. Overall, the abundance of the female mosquito positive to human blood was 4.25% per human shelter versus 17.5% per animal shelter. This result indicates that the vectors had tendency to rest in animal shelters after feeding on human. Therefore, vector control measure should be planned based on such as feeding pattern, abundance, and resting behavior of these vectors in the area. PMID:21559055
Background The relative roles of climate variability and population related effects in malaria transmission could be better understood if regional-scale dynamical malaria models could account for these factors. Methods A new dynamical community malaria model is introduced that accounts for the temperature and rainfall influences on the parasite and vector life cycles which are finely resolved in order to correctly represent the delay between the rains and the malaria season. The rainfall drives a simple but physically based representation of the surface hydrology. The model accounts for the population density in the calculation of daily biting rates. Results Model simulations of entomological inoculation rate and circumsporozoite protein rate compare well to data from field studies from a wide range of locations in West Africa that encompass both seasonal endemic and epidemic fringe areas. A focus on Bobo-Dioulasso shows the ability of the model to represent the differences in transmission rates between rural and peri-urban areas in addition to the seasonality of malaria. Fine spatial resolution regional integrations for Eastern Africa reproduce the malaria atlas project (MAP) spatial distribution of the parasite ratio, and integrations for West and Eastern Africa show that the model grossly reproduces the reduction in parasite ratio as a function of population density observed in a large number of field surveys, although it underestimates malaria prevalence at high densities probably due to the neglect of population migration. Conclusions A new dynamical community malaria model is publicly available that accounts for climate and population density to simulate malaria transmission on a regional scale. The model structure facilitates future development to incorporate migration, immunity and interventions. PMID:23419192
Compaore, Yves Daniel; Some, A. Fabrice; Greenwood, Brian; Rosenthal, Philip J.; Sutherland, Colin; Nosten, Francois; Ouedraogo, Jean-Bosco
The WHO recommends that children living in areas of highly seasonal malaria transmission in the Sahel subregion should receive seasonal malaria chemoprevention (SMC) with sulfadoxine-pyrimethamine plus amodiaquine (SPAQ). We evaluated the use of dihydroartemisinin-piperaquine (DHAPQ) as an alternative drug that could be used if SPAQ starts to lose efficacy. A total of 1,499 children 3 to 59 months old were randomized to receive SMC with SPAQ or DHAPQ over 3 months. The primary outcome measure was the risk of clinical malaria (fever or a history of fever with a parasite density of at least 3,000/μl). A cohort of 250 children outside the trial was followed up as a control group. Molecular markers of drug resistance were assessed. The risk of a malaria attack was 0.19 in the DHAPQ group and 0.15 in the SPAQ group, an odds ratio of 1.33 (95% confidence interval [CI], 1.02 to 1.72). Efficacy of SMC compared to the control group was 77% (67% to 84%) for DHAPQ and 83% (74% to 89%) for SPAQ. pfdhfr and pfdhps mutations associated with antifolate resistance were more prevalent in parasites from children who received SPAQ than in children who received DHAPQ. Both regimens were highly efficacious and well tolerated. DHAPQ is a potential alternative drug for SMC. (This trial is registered at ClinicalTrials.gov under registration no. NCT00941785.) PMID:25918149
Zongo, Issaka; Milligan, Paul; Compaore, Yves Daniel; Some, A Fabrice; Greenwood, Brian; Tarning, Joel; Rosenthal, Philip J; Sutherland, Colin; Nosten, Francois; Ouedraogo, Jean-Bosco
The WHO recommends that children living in areas of highly seasonal malaria transmission in the Sahel subregion should receive seasonal malaria chemoprevention (SMC) with sulfadoxine-pyrimethamine plus amodiaquine (SPAQ). We evaluated the use of dihydroartemisinin-piperaquine (DHAPQ) as an alternative drug that could be used if SPAQ starts to lose efficacy. A total of 1,499 children 3 to 59 months old were randomized to receive SMC with SPAQ or DHAPQ over 3 months. The primary outcome measure was the risk of clinical malaria (fever or a history of fever with a parasite density of at least 3,000/μl). A cohort of 250 children outside the trial was followed up as a control group. Molecular markers of drug resistance were assessed. The risk of a malaria attack was 0.19 in the DHAPQ group and 0.15 in the SPAQ group, an odds ratio of 1.33 (95% confidence interval [CI], 1.02 to 1.72). Efficacy of SMC compared to the control group was 77% (67% to 84%) for DHAPQ and 83% (74% to 89%) for SPAQ. pfdhfr and pfdhps mutations associated with antifolate resistance were more prevalent in parasites from children who received SPAQ than in children who received DHAPQ. Both regimens were highly efficacious and well tolerated. DHAPQ is a potential alternative drug for SMC. (This trial is registered at ClinicalTrials.gov under registration no. NCT00941785.).
Mahama, Princess R.; Tagbor, Harry; Cairns, Matt; Newell, James N.
Background Seasonal Malaria Chemoprevention (SMC) is currently recommended for children under five in areas where malaria transmission is highly seasonal. We explored children’s caregivers’ and community health workers’ (CHWs) responses to an extended 5-month SMC programme. Methods Thirteen in-depth interviews and eight focus group discussions explored optimal and suboptimal ‘uptake’ of SMC to examine facilitators and barriers to caregivers’ uptake. Results There did not appear to be major differences between caregivers of children with optimal and sub-optimal SMC uptake in terms of their knowledge of malaria, their perceptions of the effect of SMC on a child’s health, nor their understanding of chemoprevention. Caregivers experienced difficulty in prioritising SMC for well children, perceiving medication being for treatment rather than prevention. Prior to the study, caregivers had become accustomed to rapid diagnostic testing (RDT) for malaria, and therefore blood testing for malaria during the baseline survey at the start of the SMC programme may have positively influenced uptake. Facilitators of uptake included caregivers’ trust in and respect for administrators of SMC (including CHWs), access to medication and supportive (family) networks. Barriers to uptake related to poor communication of timings of community gatherings, travel distances, absence during SMC home deliveries, and limited demand for SMC due to lack of previous experience. Future delivery of SMC by trained CHWs would be acceptable to caregivers. Conclusion A combination of caregivers’ physical access to SMC medication, the drug regimen, trust in the medical profession and perceived norms around malaria prevention all likely influenced caregivers’ level of uptake. SMC programmes need to consider: 1) developing supportive, accessible and flexible modes of drug administration including home delivery and village community kiosks; 2) improving demand for preventive medication
Ould Ahmedou Salem, Mohamed Salem; Basco, Leonardo K; Ouldabdallahi, Mohamed; Mint Lekweiry, Khadijetou; Konaté, Lassana; Faye, Ousmane; Ould Mohamed Salem Boukhary, Ali
Reliable epidemiological data based on laboratory-confirmed cases are scarce in Mauritania. A large majority of reported malaria cases are based on presumptive clinical diagnosis. The present study was conducted to establish a reliable database on malaria morbidity among febrile paediatric and adult patients consulting spontaneously at public health facilities in Nouakchott, situated in the Saharan zone, and in Hodh Elgharbi region in the Sahelian zone in south-east Mauritania during the peak transmission periods. Giemsa-stained thin and thick films were examined under the microscope, and the parasite density was determined according to the procedures recommended by the World Health Organization. Microscopy results were confirmed by rapid diagnostic test for malaria. A total of 1161 febrile patients (498 in Nouakchott and 663 in Hodh Elgharbi region) were enrolled during two successive peak transmission periods in 2009 and 2010. In Nouakchott, 253 (50.8%) febrile patients had positive smears (83% Plasmodium vivax monoinfections and 17% Plasmodium falciparum monoinfections). In Hodh Elgharbi, 378 of 663 patients (57.0%) were smear-positive, mostly due to P. falciparum monoinfections (96.6%). Unlike in Nouakchott, mixed P. falciparum-P. vivax infections, as well as P. vivax, P. ovale, and P. malariae monoinfections, were also observed at a very low prevalence in southern Mauritania. In Nouakchott, malaria occurred more frequently (P<0.05) with higher slide positivity rates (42-53%) among children aged >5 years old and adults than in young children aged <5 years old in both 2009 and 2010. In Hodh Elgharbi, high slide positivity rates (60.9-86.2%) were observed in all age groups in 2010, and there was no significant trend (P>0.05) in relation with age groups. The present study confirmed the predominance of P. falciparum in southern Mauritania reported in previous studies. The presence of P. vivax in Nouakchott is a new epidemiological reality that requires an urgent
Background During the last decades two dams were constructed along the Senegal River. These intensified the practice of agriculture along the river valley basin. We conducted a study to assess malaria vector diversity, dynamics and malaria transmission in the area. Methods A cross-sectional entomological study was performed in September 2008 in 20 villages of the middle Senegal River valley to evaluate the variations of Anopheles density according to local environment. A longitudinal study was performed, from October 2008 to January 2010, in 5 selected villages, to study seasonal variations of malaria transmission. Results Among malaria vectors, 72.34% of specimens collected were An. arabiensis, 5.28% An. gambiae of the S molecular form, 3.26% M form, 12.90% An. pharoensis, 4.70% An. ziemanni, 1.48% An. funestus and 0.04% An. wellcomei. Anopheles density varied according to village location. It ranged from 0 to 21.4 Anopheles/room/day and was significantly correlated with the distance to the nearest ditch water but not to the river. Seasonal variations of Anopheles density and variety were observed with higher human biting rates during the rainy season (8.28 and 7.55 Anopheles bite/man/night in October 2008 and 2009 respectively). Transmission was low and limited to the rainy season (0.05 and 0.06 infected bite/man/night in October 2008 and 2009 respectively). During the rainy season, the endophagous rate was lower, the anthropophagic rate higher and L1014F kdr frequency higher. Conclusions Malaria vectors are present at low-moderate density in the middle Senegal River basin with An. arabiensis as the predominant species. Other potential vectors are An. gambiae M and S form and An. funestus. Nonetheless, malaria transmission was extremely low and seasonal. PMID:22269038
... a parasite. You get it when an infected mosquito bites you. Malaria is a major cause of ... insect repellent with DEET Cover up Sleep under mosquito netting Centers for Disease Control and Prevention
... Malaria can be carried by mosquitoes in temperate climates, but the parasite disappears over the winter. The ... a major disease hazard for travelers to warm climates. In some areas of the world, mosquitoes that ...
established, the infection is classi- fied as cryptic malaria. A large majority of infections are transmitted by the bite of an infected female ... female anopheline mosquitoes. Plasmodium sp infecting humans include Plasmodium vivax, Plasmodium falci- parum, Plasmodium malariae, and Plasmodium ovale...paled and pigment formed within them. Later he observed male gametes form by exflagellation and described the male and female gam- etes, the
Maghsoodi, Naimatallah; Ladonni, Hossin; Basseri, Hamid Reza
Background: The most part of Iran become malaria-free region and fall in prevention of re-introduction stage. These regions however are struggling with imported of malaria cases where malaria vectors exist. Therefore, understanding the situation of mosquito vectors is crucial. This study was carried out to find out the present situation of malaria vectors and malaria transmission potential in a malaria-free area. Methods: The study was conducted in a malaria free area, Izeh County, Khuzestan Province during 12 months in 2011–2012. Five villages, including 2 in highlands and 3 in plain area, were selected randomly. The mosquito sampling methods were conducted using spray sheet and hand catch collection methods from indoor/outdoors, window trap and larvae collections. Results: In total, 3352 female Anopheles were captured, 1826 mosquito from highland and 1526 from plain areas. Five species, An. stephensi, An. fluviatilis s.l., An. dthali, An. superpictus and An. pulcherrimus were identified. The seasonal activities were started from April to March. The abdominal conditions of collected mosquitoes from indoor/outdoor places pointed to exophilic propensity of An. fluviatilis.l. s.l. and endophilic behaviour for rest of the vectors. The results of window trap also confirmed these behaviors. The larval habitats of four species were widely dispersed and included spring, margin of rivers, irrigation channels, stagnant water and rice filed. Conclusion: Understanding the present situation of malaria vectors in free-malaria area is crucial particularly where is struggling with imported cases. The results of present study can be expanded to other area of northern Khuzestan for malaria vector control planning in reintroduction prevention stage. PMID:26114144
Background Development of large scale agro-industries are subject to serious environmental modifications. In malaria endemic areas this would greatly impact on the transmission paradigm. Two cross-sectional entomological surveys to characterize the Anopheles fauna and their entomological inoculation rates were conducted during May 2010 (peak rainy season) and December 2010 (peak dry season) in the intense rubber cultivated area of Niete in southern forested Cameroon. Methods Mosquitoes were sampled by night collections on human volunteers, identified morphologically and members of the Anopheles gambiae complex further identified to species and molecular form. Parity status was determined following the dissection of the ovaries. Plasmodium falciparum circumsporozoite antigen indices were estimated after the identification of CS antigen by ELISA and the average entomological inoculation rates determined. Results A total of 1187 Anopheles was collected, 419 (35.3%) in the rainy season and 768 (64.7%) in the dry season. Species found were the M molecular form of An. gambiae s.s (66.8%), An. ziemanni (28.3%), An. paludis (4.7%), An. smithii (0.2%). An. gambiae M-form was the principal species in the dry (56.2%) and wet (86.2%) seasons. Average overall entomological inoculation rate for the malaria vectors varied between the dry season (1.09 ib/p/n) and the rainy season (2.30 ib/p/n). Conclusions Malaria transmission in Niete occurs both in the dry and rainy season with the intensities peaking in the dry season. This is unlike previous studies in other areas of southern forested Cameroon where transmission generally peaks in the rainy season. Environmental modifications due to agro-industrial activities might have influenced vector distribution and the dynamics of malaria transmission in this area. This necessitates the possible implementation of control strategies that are related to the eco-geography of the area. PMID:22963986
Giha, Hayder A
Chloroquine (CQ) is outmoded as an antimalarial drug in most of the malarial world because of the high resistance rate of parasites. The parasite resistance to CQ is attributed to pfcrt/pfmdr1 gene mutations. Recent studies showed that parasites with mutations of pfcrt/pfmdr1 genes are less virulent, and that those with dhfr/dhps mutations are more susceptible to host immune clearance; the former and latter mutations are linked. In the era of artemisinin-based combination therapy, the frequency of pfcrt/pfmdr1 wild variants is expected to rise. In areas of unstable malaria transmission, the unpredictable severe epidemics of malaria and epidemics of severe malaria could result in high mortality rate among the semi-immune population. With this in mind, the use of CQ for intermittent preventive treatment of adults (IPTa) is suggested as a feasible control measure to reduce malaria mortality in adults and older children without reducing uncomplicated malaria morbidity. The above is discussed in a multidisciplinary approach validating the deployment of molecular techniques in malaria control and showing a possible role for CQ as a rescue drug after being abandoned.
Schaffer, W M; Bronnikova, T V
Forty years after the World Health Organization abandoned its eradication campaign, malaria remains a public health problem of the first magnitude with worldwide infection rates on the order of 300 million souls. The present paper reviews potential control strategies from the viewpoint of mathematical epidemiology. Following MacDonald and others, we argue in Section 1 that the use of imagicides, i.e., killing, or at least repelling, adult mosquitoes, is inherently the most effective way of combating the pandemic. In Section 2, we model competition between wild-type (WT) and plasmodium-resistant, genetically modified (GM) mosquitoes. Under the assumptions of inherent cost and prevalence-dependant benefit to transgenics, GM introduction can never eradicate malaria save by stochastic extinction of WTs. Moreover, alternative interventions that reduce prevalence have the undesirable consequence of reducing the likelihood of successful GM introduction. Section 3 considers the possibility of using seasonal fluctuations in mosquito abundance and disease prevalence to 'slingshot' GM mosquitoes into natural populations. By introducing GM mosquitoes when natural populations are about to expand, one can 'piggyback' on the yearly cycle. Importantly, this effect is only significant when transgene cost is small, in which case the non-trivial equilibrium is a focus (damped oscillations), and piggybacking is amplified by the system's inherent tendency to oscillate. By way of contrast, when transgene cost is large, the equilibrium is a node and no such amplification is obtained.
Lal, Sham; Ndyomugenyi, Richard; Magnussen, Pascal; Hansen, Kristian S.; Alexander, Neal D.; Paintain, Lucy; Chandramohan, Daniel; Clarke, Siân E.
Malaria-endemic countries have implemented community health worker (CHW) programs to provide malaria diagnosis and treatment to populations living beyond the reach of health systems. However, there is limited evidence describing the referral practices of CHWs. We examined the impact of malaria rapid diagnostic tests (mRDTs) on CHW referral in two cluster-randomized trials, one conducted in a moderate-to-high malaria transmission setting and one in a low-transmission setting in Uganda, between January 2010 and July 2012. All CHWs were trained to prescribe artemisinin-based combination therapy (ACT) for malaria and recognize signs and symptoms for referral to health centers. CHWs in the control arm used a presumptive diagnosis for malaria based on clinical symptoms, whereas intervention arm CHWs used mRDTs. CHWs recorded ACT prescriptions, mRDT results, and referral in patient registers. An intention-to-treat analysis was undertaken using multivariable logistic regression. Referral was more frequent in the intervention arm versus the control arm (moderate-to-high transmission, P < 0.001; low transmission, P < 0.001). Despite this increase, referral advice was not always given when ACTs or prereferral rectal artesunate were prescribed: 14% prescribed rectal artesunate in the moderate-to-high setting were not referred. In addition, CHWs considered factors alongside mRDTs when referring. Child visits during the weekends or the rainy season were less likely to be referred, whereas visits to CHWs more distant from health centers were more likely to be referred (low transmission only). CHWs using mRDTs and ACTs increased referral compared with CHWs using a presumptive diagnosis. To address these concerns, referral training should be emphasized in CHW programs as they are scaled-up. PMID:27799650
Cissé, Badara; Sokhna, Cheikh; NDiaye, Jean Louis; Gomis, Jules F.; Dial, Yankhoba; Pitt, Catherine; NDiaye, Mouhamed; Cairns, Matthew; Faye, Ernest; NDiaye, Magatte; Tine, Roger; Faye, Sylvain; Faye, Babacar; Sy, Ousmane; Konate, Lansana; Kouevijdin, Ekoue; Flach, Clare; Faye, Ousmane; Trape, Jean-Francois; Sutherland, Colin; Fall, Fatou Ba; Thior, Pape M.; Faye, Oumar K.; Greenwood, Brian; Gaye, Oumar; Milligan, Paul
Background Seasonal Malaria Chemoprevention (SMC) with sulfadoxine-pyrimethamine (SP) plus amodiaquine (AQ), given each month during the transmission season, is recommended for children living in areas of the Sahel where malaria transmission is highly seasonal. The recommendation for SMC is currently limited to children under five years of age, but, in many areas of seasonal transmission, the burden in older children may justify extending this age limit. This study was done to determine the effectiveness of SMC in Senegalese children up to ten years of age. Methods and Findings SMC was introduced into three districts over three years in central Senegal using a stepped-wedge cluster-randomised design. A census of the population was undertaken and a surveillance system was established to record all deaths and to record all cases of malaria seen at health facilities. A pharmacovigilance system was put in place to detect adverse drug reactions. Fifty-four health posts were randomised. Nine started implementation of SMC in 2008, 18 in 2009, and a further 18 in 2010, with 9 remaining as controls. In the first year of implementation, SMC was delivered to children aged 3–59 months; the age range was then extended for the latter two years of the study to include children up to 10 years of age. Cluster sample surveys at the end of each transmission season were done to measure coverage of SMC and the prevalence of parasitaemia and anaemia, to monitor molecular markers of drug resistance, and to measure insecticide-treated net (ITN) use. Entomological monitoring and assessment of costs of delivery in each health post and of community attitudes to SMC were also undertaken. About 780,000 treatments were administered over three years. Coverage exceeded 80% each month. Mortality, the primary endpoint, was similar in SMC and control areas (4.6 and 4.5 per 1000 respectively in children under 5 years and 1.3 and 1.2 per 1000 in children 5-9 years of age; the overall mortality rate
Background Formerly a high malaria transmission area, Zanzibar is now targeting malaria elimination. A major challenge is to avoid resurgence of malaria, the success of which includes maintaining high effective coverage of vector control interventions such as bed nets and indoor residual spraying (IRS). In this study, caretakers' continued use of preventive measures for their children is evaluated, following a sharp reduction in malaria transmission. Methods A cross-sectional community-based survey was conducted in June 2009 in North A and Micheweni districts in Zanzibar. Households were randomly selected using two-stage cluster sampling. Interviews were conducted with 560 caretakers of under-five-year old children, who were asked about perceptions on the malaria situation, vector control, household assets, and intention for continued use of vector control as malaria burden further decreases. Results Effective coverage of vector control interventions for under-five children remains high, although most caretakers (65%; 363/560) did not perceive malaria as presently being a major health issue. Seventy percent (447/643) of the under-five children slept under a long-lasting insecticidal net (LLIN) and 94% (607/643) were living in houses targeted with IRS. In total, 98% (628/643) of the children were covered by at least one of the vector control interventions. Seasonal bed-net use for children was reported by 25% (125/508) of caretakers of children who used bed nets. A high proportion of caretakers (95%; 500/524) stated that they intended to continue using preventive measures for their under-five children as malaria burden further reduces. Malaria risk perceptions and different perceptions of vector control were not found to be significantly associated with LLIN effective coverage. Conclusions While the majority of caretakers felt that malaria had been reduced in Zanzibar, effective coverage of vector control interventions remained high. Caretakers appreciated the
Kim, Min-Jae; Jung, Bong-Kwang; Chai, Jong-Yil; Eom, Keeseon S.; Yong, Tai-Soon; Min, Duk-Young; Siza, Julius E.; Kaatano, Godfrey M.; Kuboza, Josephat; Mnyeshi, Peter; Changalucha, John M.; Ko, Yunsuk; Chang, Su Young; Rim, Han-Jong
In order to determine the status of malaria among schoolchildren on Kome Island (Lake Victoria), near Mwanza, Tanzania, a total of 244 schoolchildren in 10 primary schools were subjected to a blood survey using the fingerprick method. The subjected schoolchildren were 123 boys and 121 girls who were 6-8 years of age. Only 1 blood smear was prepared for each child. The overall prevalence of malaria was 38.1% (93 positives), and sex difference was not remarkable. However, the positive rate was the highest in Izindabo Primary School (51.4%) followed by Isenyi Primary School (48.3%) and Bugoro Primary School (46.7%). The lowest prevalence was found in Muungano Primary School (16.7%) and Nyamiswi Primary School (16.7%). These differences were highly correlated with the location of the school on the Island; those located in the peripheral area revealed higher prevalences while those located in the central area showed lower prevalences. Plasmodium falciparum was the predominant species (38.1%; 93/244), with a small proportion of them mixed-infected with Plasmodium vivax (1.6%; 4/244). The results revealed that malaria is highly prevalent among primary schoolchildren on Kome Island, Tanzania, and there is an urgent need to control malaria in this area. PMID:26537036
Lobo, Lis; de Sousa, Bruno; Cabral, Lília; Cristiano, Maria LS; Nogueira, Fátima
Ever increasing multi-drug resistance by Plasmodium falciparum is creating new challenges in malaria chemotherapy. In the absence of licensed vaccines, treatment and prevention of malaria is heavily dependent on drugs. Potency, range of activity, safety, low cost and ease of administration are crucial issues in the design and formulation of antimalarials. We have tested three synthetic ozonides NAC89, LC50 and LCD67 in vitro and in vivo against multidrug resistant Plasmodium. In vitro, LC50 was at least 10 times more efficient inhibiting P. falciparum multidrug resistant Dd2 strain than chloroquine and mefloquine and as efficient as artemisinin (ART), artesunate and dihydroartemisinin. All three ozonides showed high efficacy in clearing parasitaemia in mice, caused by multi-drug resistant Plasmodium chabaudi strains, by subcutaneous administration, demonstrating high efficacy in vivo against ART and artesunate resistant parasites. PMID:27276364
Lobo, Lis; Sousa, Bruno de; Cabral, Lília; Cristiano, Maria Ls; Nogueira, Fátima
Ever increasing multi-drug resistance by Plasmodium falciparum is creating new challenges in malaria chemotherapy. In the absence of licensed vaccines, treatment and prevention of malaria is heavily dependent on drugs. Potency, range of activity, safety, low cost and ease of administration are crucial issues in the design and formulation of antimalarials. We have tested three synthetic ozonides NAC89, LC50 and LCD67 in vitro and in vivo against multidrug resistant Plasmodium. In vitro, LC50 was at least 10 times more efficient inhibiting P. falciparum multidrug resistant Dd2 strain than chloroquine and mefloquine and as efficient as artemisinin (ART), artesunate and dihydroartemisinin. All three ozonides showed high efficacy in clearing parasitaemia in mice, caused by multi-drug resistant Plasmodium chabaudi strains, by subcutaneous administration, demonstrating high efficacy in vivo against ART and artesunate resistant parasites.
Machault, Vanessa; Gadiaga, Libasse; Vignolles, Cécile; Jarjaval, Fanny; Bouzid, Samia; Sokhna, Cheikh; Lacaux, Jean-Pierre; Trape, Jean-François; Rogier, Christophe; Pagès, Frédéric
densities was found in six of the ten study areas. Conclusion The results provide evidence of malaria transmission in downtown Dakar and its surrounding suburbs. Spatial heterogeneity of human biting rates was very marked and malaria transmission was highly focal. In Dakar, mean figures for transmission would not provide a comprehensive picture of the entomological situation; risk evaluation should therefore be undertaken on a small scale. PMID:19552809
Vezenegho, Samuel B; Adde, Antoine; de Santi, Vincent Pommier; Issaly, Jean; Carinci, Romuald; Gaborit, Pascal; Dusfour, Isabelle; Girod, Romain; Briolant, Sébastien
In French Guiana, malaria vector control and prevention relies on indoor residual spraying and distribution of long lasting insecticidal nets. These measures are based on solid epidemiological evidence but reveal a poor understanding of the vector. The current study investigated the behaviour of both vectors and humans in relation to the ongoing prevention strategies. In 2012 and 2013, Anopheles mosquitoes were sampled outdoors at different seasons and in various time slots. The collected mosquitoes were identified and screened for Plasmodium infection. Data on human behaviour and malaria episodes were obtained from an interview. A total of 3,135 Anopheles mosquitoes were collected, of which Anopheles darlingi was the predominant species (96.2%). For the December 2012-February 2013 period, the Plasmodium vivax infection rate for An. darlingi was 7.8%, and the entomological inoculation rate was 35.7 infective bites per person per three-month span. In spite of high bednet usage (95.7%) in 2012 and 2013, 52.2% and 37.0% of the participants, respectively, had at least one malaria episode. An. darlingi displayed heterogeneous biting behaviour that peaked between 20:30 and 22:30; however, 27.6% of the inhabitants were not yet protected by bednets by 21:30. The use of additional individual and collective protective measures is required to limit exposure to infective mosquito bites and reduce vector densities. PMID:27653361
Beck, Louisa R.; Rodriquez, Mario H.; Dister, Sheri W.; Rodriquez, Americo D.; Rejmankova, Eliska; Ulloa, Armando; Meza, Rosa A.; Roberts, Donald R.; Paris, Jack F.; Spanner, Michael A.; Washino, Robert K.; Hacker, Carl; Legters, Llewellyn F.
A landscape approach using remote sensing and Geographic Information System (GIS) technologies was developed to discriminate between villages at high and low risk for malaria transmission, as defined by adult Anopheles albimanus abundance. Satellite data for an area in southern Chiapas, Mexico were digitally processed to generate a map of landscape elements. The GIS processes were used to determine the proportion of mapped landscape elements surrounding 40 villages where An. albimanus data had been collected. The relationships between vector abundance and landscape element proportions were investigated using stepwise discriminant analysis and stepwise linear regression. Both analyses indicated that the most important landscape elements in terms of explaining vector abundance were transitional swamp and unmanaged pasture. Discriminant functions generated for these two elements were able to correctly distinguish between villages with high ind low vector abundance, with an overall accuracy of 90%. Regression results found both transitional swamp and unmanaged pasture proportions to be predictive of vector abundance during the mid-to-late wet season. This approach, which integrates remotely sensed data and GIS capabilities to identify villages with high vector-human contact risk, provides a promising tool for malaria surveillance programs that depend on labor-intensive field techniques. This is particularly relevant in areas where the lack of accurate surveillance capabilities may result in no malaria control action when, in fact, directed action is necessary. In general, this landscape approach could be applied to other vector-borne diseases in areas where: 1. the landscape elements critical to vector survival are known and 2. these elements can be detected at remote sensing scales.
Fillol, Florie; Cournil, Amandine; Boulanger, Denis; Cissé, Badara; Sokhna, Cheikh; Targett, Geoffrey; Trape, Jean-François; Simondon, François; Greenwood, Brian; Simondon, Kirsten B
In sub-Saharan Africa, malaria and malnutrition are major causes of morbidity and mortality in children less than five years of age. To explore the impact of malnutrition on subsequent susceptibility to malaria, a cohort of 874 rural preschool children in Senegal was followed-up during one malaria transmission season from July through December. Data on nutritional status and Plasmodium falciparum parasitemia were collected at baseline. Malaria morbidity was monitored through weekly home visits. Wasted children (weight-for-height z-score < -2) were at lower risk of having at least one subsequent clinical malaria attack (odds ratio = 0.33; 95% confidence interval = 0.13-0.81, P = 0.02), whereas stunting (height-for-age z-score < -2) or being underweight (weight-for-age z-score < -2) was not associated with clinical malaria. Although non-biological explanations such as overprotection of wasted children by their mothers should be considered, immunomodulation according to nutritional status could explain the lower risk of malaria attack among wasted children.
Gil, Luiz Herman Soares; Tada, Mauro Shugiro; Katsuragawa, Tony Hiroshi; Ribolla, Paulo Eduardo Martins; da Silva, Luiz Hildebrando Pereira
Longitudinal entomological surveys were performed in Vila Candelária and adjacent rural locality of Bate Estaca concomitantly with a clinical epidemiologic malaria survey. Vila Candelária is a riverside periurban neighborhood of Porto Velho, capital of the state of Rondônia in the Brazilian Amazon. High anopheline densities were found accompanying the peak of rainfall, as reported in rural areas of the region. Moreover, several minor peaks of anophelines were recorded between the end of the dry season and the beginning of the next rainy season. These secondary peaks were related to permanent anopheline breeding sites resulting from human activities. Malaria transmission is, therefore, observed all over the year. In Vila Candelária, the risk of malaria infection both indoors and outdoors was calculated as being 2 and 10/infecting bites per year per inhabitant respectively. Urban malaria in riverside areas was associated with two factors: (1) high prevalence of asymptomatic carriers in a stable human population and (2) high anopheline densities related to human environmental changes. This association is probably found in other Amazonian urban and suburban communities. The implementation of control measures should include environmental sanitation and better characterization of the role of asymptomatic carriers in malaria transmission.
Zevering, Y; Amante, F; Smillie, A; Currier, J; Smith, G; Houghten, R A; Good, M F
A major goal of current candidate malaria vaccines is to stimulate the expansion of clones of malaria-specific lymphocytes. We have examined the in vitro T cell responses of a group of malaria exposed and non-exposed adult Caucasian donors to recombinant circumsporozoite (CS) proteins, one of which is undergoing clinical trials, to blood-stage parasites, and to synthetic peptides copying the CS protein and defined blood-stage proteins. In nearly all individuals tested, CD4 T cell proliferation or lymphokine production occurred in response to whole parasite or CS protein stimulation, and T cells from many individuals responded to synthetic peptides. T cell responses were major histocompatibility complex-restricted, and stimulation of T cells with malaria parasites or CS protein did not appear to expand a population of T cell receptor gamma/delta cells. Malaria-specific responses were independent of prior malaria exposure, and in some cases exceeded the magnitude of response to tetanus toxoid. Specific T cells are present in high frequency in the peripheral blood of many donors who have never been exposed to malaria. Although malaria-specific CD4 T cells play an important role in immunity, these data question whether vaccines need to stimulate such cells, and focus attention on other aspects of malaria immunity which may be more critical to a successful vaccine.
Suswardany, Dwi Linna; Sibbritt, David W.; Supardi, Sudibyo; Pardosi, Jerico F.; Chang, Sungwon; Adams, Jon
Background The level of traditional medicine use, particularly Jamu use, in Indonesia is substantial. Indonesians do not always seek timely treatment for malaria and may seek self-medication via traditional medicine. This paper reports findings from the first focused analyses of traditional medicine use for malaria in Indonesia and the first such analyses worldwide to draw upon a large sample of respondents across high-risk malaria endemic areas. Methods A sub-study of the Indonesia Basic Health Research/Riskesdas Study 2010 focused on 12,226 adults aged 15 years and above residing in high-risk malaria-endemic provinces. Logistic regression was undertaken to determine the significant associations for traditional medicine use for malaria symptoms. Findings Approximately one in five respondents use traditional medicine for malaria symptoms and the vast majority experiencing multiple episodes of malaria use traditional medicine alongside free antimalarial drug treatments. Respondents consuming traditional medicine for general health/common illness purposes every day (odds ratio: 3.75, 95% Confidence Interval: 2.93 4.79), those without a hospital in local vicinity (odds ratio: 1.31, 95% Confidence Interval: 1.10 1.57), and those living in poorer quality housing, were more likely to use traditional medicine for malaria symptoms. Conclusion A substantial percentage of those with malaria symptoms utilize traditional medicine for treating their malaria symptoms. In order to promote safe and effective malaria treatment, all providing malaria care in Indonesia need to enquire with their patients about possible traditional medicine use. PMID:28329019
Safety of Seasonal Malaria Chemoprevention (SMC) with Sulfadoxine-Pyrimethamine plus Amodiaquine when Delivered to Children under 10 Years of Age by District Health Services in Senegal: Results from a Stepped-Wedge Cluster Randomized Trial
NDiaye, J. L.; Cissé, B.; Ba, E. H.; Gomis, J. F.; Ndour, C. T.; Molez, J. F.; Fall, F. B.; Sokhna, C.; Faye, B.; Kouevijdin, E.; Niane, F. K.; Cairns, M.; Trape, J. F.; Rogier, C.; Gaye, O.; Greenwood, B. M.; Milligan, P. J. M.
Background It is recommended that children aged 3 months to five years of age living in areas of seasonal transmission in the sub-Sahel should receive Seasonal Malaria Chemoprevention (SMC) with sulfadoxine-pyrimethamine plus amodiaquine (SPAQ) during the malaria transmission season. The purpose of this study was to evaluate the safety of SMC with SPAQ in children when delivered by community health workers in three districts in Senegal where SMC was introduced over three years, in children from 3 months of age to five years of age in the first year, then in children up to 10 years of age. Methods A surveillance system was established to record all deaths and all malaria cases diagnosed at health facilities and a pharmacovigilance system was established to detect adverse drug reactions. Health posts were randomized to introduce SMC in a stepped wedge design. SMC with SPAQ was administered once per month from September to November, by nine health-posts in 2008, by 27 in 2009 and by 45 in 2010. Results After three years, 780,000 documented courses of SMC had been administered. High coverage was achieved. No serious adverse events attributable to the intervention were detected, despite a high level of surveillance. Conclusions SMC is being implemented in countries of the sub-Sahel for children under 5 years of age, but in some areas the age distribution of cases of malaria may justify extending this age limit, as has been done in Senegal. Our results show that SMC is well tolerated in children under five and in older children. However, pharmacovigilance should be maintained where SMC is implemented and provision for strengthening national pharmacovigilance systems should be included in plans for SMC implementation. Trial Registration ClinicalTrials.gov NCT 00712374 PMID:27764102
Bosomprah, Samuel; Kyei-Baafour, Eric; Dickson, Emmanuel K.; Tornyigah, Bernard; Angov, Evelina; Dutta, Sheetij; Dodoo, Daniel; Sedegah, Martha; Koram, Kwadwo A.
Introduction As an increasing number of malaria-endemic countries approach the disease elimination phase, sustenance of control efforts and effective monitoring are necessary to ensure success. Mathematical models that estimate anti-parasite antibody seroconversion rates are gaining relevance as more sensitive transmission intensity estimation tools. Models however estimate yearly seroconversion and seroreversion rates and usually predict long term changes in transmission, occurring years before the time of sampling. Another challenge is the identification of appropriate antigen targets since specific antibody levels must directly reflect changes in transmission patterns. We therefore investigated the potential of antibodies to sporozoite and blood stage antigens for detecting short term differences in malaria transmission in two communities in Northern Ghana with marked, seasonal transmission. Methods Cross-sectional surveys were conducted during the rainy and dry seasons in two communities, one in close proximity to an irrigation dam and the other at least 20 Km away from the dam. Antibodies against the sporozoite-specific antigens circumsporozoite protein (CSP) and Cell traversal for ookinetes and sporozoites (CelTOS) and the classical blood stage antigen apical membrane antigen 1 (AMA1) were measured by indirect ELISA. Antibody levels and seroprevalence were compared between surveys and between study communities. Antibody seroprevalence data were fitted to a modified reversible catalytic model to estimate the seroconversion and seroreversion rates. Results Changes in sporozoite-specific antibody levels and seroprevalence directly reflected differences in parasite prevalence between the rainy and dry seasons and hence the extent of malaria transmission. Seroconversion rate estimates from modelled seroprevalence data did not however support the above observation. Conclusions The data confirms the potential utility of sporozoite-specific antigens as useful markers
Mukiama, T K; Mwangi, R W
A study in 1984 and 1985 showed that Anopheles gambiae s.l. and An. pharoensis were the major anophelines in Mwea Irrigation Scheme, Kenya, constituting 83.86% and 15.69% of the catch respectively. Four minor species made up the remaining 0.45%. The irrigation phase of the rice cultivation cycle in August, which linked the flooding effects of the two rainy seasons, resulted in major population increases of An. pharoensis and enabled continuous breeding for up to 9 months per year. The average of mean monthly proportions of unfed, bloodfed, and gravid females was 26.6, 58.8, and 14.6% respectively. The Plasmodium falciparum sporozoite rates for An. pharoensis were 1.3% by ELISA and 0.68% by dissection, while those for An. funestus were 1.7% by ELISA and 1.25% by dissection. An. pharoensis can contribute to the epidemiology of Malaria in the Mwea area.
Huang, Xin; Song, Yu; Li, Mengmeng; Li, Jianfeng; Zhu, Tong
East China, a major agricultural zone with a dense population, suffers from severe air pollution during June, the agricultural harvest season, every year. Crop burning emits tremendous amounts of combustion products into the atmosphere, not only rapidly degrading the local air quality but also affecting the tropospheric chemistry, threatening public health and affecting climate change. Recently, in mid-June 2012, crop fires left a thick pall of haze over East China. We evaluated the PM10, PM2.5 (particulates less than 10 and 2.5 μm in aerodynamic diameter) and BC (black carbon) emissions by analyzing detailed census data and moderate resolution imaging spectroradiometer (MODIS) remote sensing images and then simulated the consequent pollution using meteorological and dispersion models. The results show that the crop fires sweeping from the south to the north are responsible for the intensive air pollution during harvest season. It is necessary for scientists and governments to pay more attention to this issue.
Background Control of mosquitoes that transmit malaria has been the mainstay in the fight against the disease, but alternative methods are required in view of emerging insecticide resistance. Entomopathogenic fungi are candidate alternatives, but to date, few trials have translated the use of these agents to field-based evaluations of their actual impact on mosquito survival and malaria risk. Mineral oil-formulations of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were applied using five different techniques that each exploited the behaviour of malaria mosquitoes when entering, host-seeking or resting in experimental huts in a malaria endemic area of rural Tanzania. Results Survival of mosquitoes was reduced by 39-57% relative to controls after forcing upward house-entry of mosquitoes through fungus treated baffles attached to the eaves or after application of fungus-treated surfaces around an occupied bed net (bed net strip design). Moreover, 68 to 76% of the treatment mosquitoes showed fungal growth and thus had sufficient contact with fungus treated surfaces. A population dynamic model of malaria-mosquito interactions shows that these infection rates reduce malaria transmission by 75-80% due to the effect of fungal infection on adult mortality alone. The model also demonstrated that even if a high proportion of the mosquitoes exhibits outdoor biting behaviour, malaria transmission was still significantly reduced. Conclusions Entomopathogenic fungi strongly affect mosquito survival and have a high predicted impact on malaria transmission. These entomopathogens represent a viable alternative for malaria control, especially if they are used as part of an integrated vector management strategy. PMID:22449130
Castelli, Francesco; Odolini, Silvia; Autino, Beatrice; Foca, Emanuele; Russo, Rosario
The flow of international travellers to and from malaria-endemic areas, especially Africa, has increased in recent years. Apart from the very high morbidity and mortality burden imposed on malaria-endemic areas, imported malaria is the main cause of fever possibly causing severe disease and death in travellers coming from tropical and subtropical areas, particularly Sub-Saharan Africa. The importance of behavioural preventive measures (bed nets, repellents, etc.), adequate chemoprophylaxis and, in selected circumstances, stand-by emergency treatment may not be overemphasized. However, no prophylactic regimen may offer complete protection. Expert advice is needed to tailor prophylactic advice according to traveller (age, baseline clinical conditions, etc.) and travel (destination, season, etc.) characteristics in order to reduce malaria risk.
Objective To examine temporal, geographic, and sociodemographic trends in case reporting and case fatality of malaria in the United Kingdom. Setting National malaria reference laboratory surveillance data in the UK. Design Observational study using prospectively gathered surveillance data and data on destinations from the international passenger survey. Participants 39 300 cases of proved malaria in the UK between 1987 and 2006. Main outcome measures Plasmodium species; sociodemographic details (including age, sex, and country of birth and residence); mortality; destination, duration, and purpose of international travel; and use of chemoprophylaxis. Results Reported cases of imported malaria increased significantly over the 20 years of the study; an increasing proportion was attributable to Plasmodium falciparum (P falciparum/P vivax reporting ratio 1.3:1 in 1987-91 and 5.4:1 in 2002-6). P vivax reports declined from 3954 in 1987-91 to 1244 in 2002-6. Case fatality of reported P falciparum malaria did not change over this period (7.4 deaths per 1000 reported cases). Travellers visiting friends and relatives, usually in a country in Africa or Asia from which members of their family migrated, accounted for 13 215/20 488 (64.5%) of all malaria reported, and reports were geographically concentrated in areas where migrants from Africa and South Asia to the UK have settled. People travelling for this purpose were at significantly higher risk of malaria than other travellers and were less likely to report the use of any chemoprophylaxis (odds ratio of reported chemoprophylaxis use 0.23, 95% confidence interval 0.21 to 0.25). Conclusions Despite the availability of highly effective preventive measures, the preventable burden from falciparum malaria has steadily increased in the UK while vivax malaria has decreased. Provision of targeted and appropriately delivered preventive messages and services for travellers from migrant families visiting friends and relatives
Suliman, Makarim M. Adam; Hamad, Bushra M.; Albasheer, Musab M. Ali; Elhadi, Maytha; Elobied, Maha
Plasmodium falciparum is a predominant malaria species that infects humans in the African continent. A recent WHO report estimated 95% and 5% of P. falciparum and P. vivax malaria cases, respectively, in Sudan. However many laboratory reports from different areas in Sudan indicated otherwise. In order to verify, we selected four hundred suspected malaria cases from Aljabalain area located in the White Nile state, central Sudan, and diagnosed them with quality insured microscopy and species-specific nested PCR. Our results indicated that the proportion of P. vivax infections among suspected malaria cases was high. We found that on average 20% and 36.5% of malaria infections in both study areas were caused by P. vivax using both microscopy and PCR, respectively. This change in pattern is likely due to the recent demographic changes and high rate of immigration from neighbouring countries in the recent years. This is the first extensive clinical study of its kind that shows rising trend in P. vivax malaria cases in White Nile area, Sudan. PMID:27980861
Otsuki, Hitoshi; Yokouchi, Yuki; Iyoku, Natsumi; Tachibana, Mayumi; Tsuboi, Takafumi; Torii, Motomi
Rodent malaria is a useful model for evaluating the efficacy of malaria vaccine candidates; however, labor-intensive microscopic parasite counting hampers the use of an in vivo parasite challenge in high-throughput screening. The measurement of malaria parasite lactate dehydrogenase (pLDH) activity, which is commonly used in the in vitro growth inhibition assay of Plasmodium falciparum, may be the cheapest and simplest alternative to microscopic parasite counting. However, the pLDH assay has not been applied in the in vivo rodent malaria model. Here, we showed that the pLDH assay is reliable and accurately determines parasitemia in the rodent malaria model. pLDH activity measured using a chromogenic substrate reflects the parasite number in the blood; it allows fast and easy assessment using a conventional microplate reader. To validate this approach, we synthesized recombinant PyMSP1-19 protein (rPyMSP1-19) using a wheat germ cell-free protein synthesis system and immunized mice with rPyMSP1-19. The antisera showed specific reactivity on the surface of the Plasmodium yoelii merozoite and immunized mice were protected against a lethal P. yoelii 17 XL challenge. The pLDH assay quickly and easily demonstrated a significant reduction of the parasite numbers in the immunized mice. Accordingly, the pLDH assay proved to be an efficient alternative to rodent malaria parasite counting, and may therefore accelerate in vivo vaccine candidate screening.
Sutanto, I; Freisleben, H J; Pribadi, W; Atmosoedjono, S; Bandi, R; Purnomo
A malaria intervention study was carried out using permethrin impregnated bed nets in the south-central part of Irian Jaya with perennial transmission, from April 1993 to April 1995. Malariometric surveys were carried out periodically for parasite prevalence by species and for spleen rates. Prior to intervention, the percentage of Plasmodium falciparum infected inhabitants was significantly higher in Hiripau, where permethrin-impregnated bed nets were used during the study, than in the placebo-treated control village, Kaugapu. After two years of intervention the situation was reversed and figures higher in the control village (RR 0.19, 95% CI 0.10-0.36, p < 0.0001). Similarly, P. vivax infection rates, 12.4% in Hiripau vs 5.7% in Kaugapu in April 1993. were reversed in April 1995 (3.6% in Hiripau and 11.3% in Kaugapu, p < 0.001). In the treated village, pre-control hyperendemicity was reduced to a low mesoendemic level (spleen rate 12.5%) during two years of intervention, whereas the level was mesoendemic (spleen rate 35.2%) in the control village. Impregnated bed nets were found an effective intervention both in moderate (April 1993 through April 1994, 1,626 mm rainfall) and high (April 1994 through April 1995/1995, 3,321 mm) transmission seasons.
National Institute of Allergy and Infectious Diseases, NIH Fever is the most benign and common, and cerebral malaria is the most...his laboratory at the Regulatory and Growth Development Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and...Nigerian children during high and low transmission seasons : gametocyte carriage and response to oral chloroquine. J Trop Pediatr 51:288-294. 2
Tompkins, Adrian; Ermert, Volker; Di Giuseppe, Francesca
In order to better address the role of population dynamics and surface hydrology in the assessment of malaria risk, a new dynamical disease model been developed at ICTP, known as VECTRI: VECtor borne disease community model of ICTP, TRIeste (VECTRI). The model accounts for the temperature impact on the larvae, parasite and adult vector populations. Local host population density affects the transmission intensity, and the model thus reproduces the differences between peri-urban and rural transmission noted in Africa. A new simple pond model framework represents surface hydrology. The model can be used on with spatial resolutions finer than 10km to resolve individual health districts and thus can be used as a planning tool. Results of the models representation of interannual variability and longer term projections of malaria transmission will be shown for Africa. These will show that the model represents the seasonality and spatial variations of malaria transmission well matching a wide range of survey data of parasite rate and entomological inoculation rate (EIR) from across West and East Africa taken in the period prior to large-scale interventions. The model is used to determine the sensitivity of malaria risk to climate variations, both in rainfall and temperature, and then its use in a prototype forecasting system coupled with ECMWF forecasts will be demonstrated.
In order to identify the most attractive starting points for drugs that can be used to prevent malaria, a diverse chemical space comprising tens of thousands to millions of small molecules may need to be examined. Achieving this throughput necessitates the development of efficient ultra-high-throughput screening methods. Here, we report the development and evaluation of a luciferase-based phenotypic screen of malaria exoerythrocytic-stage parasites optimized for a 1536-well format. This assay uses the exoerythrocytic stage of the rodent malaria parasite, Plasmodium berghei, and a human hepatoma cell line. We use this assay to evaluate several biased and unbiased compound libraries, including two small sets of molecules (400 and 89 compounds, respectively) with known activity against malaria erythrocytic-stage parasites and a set of 9886 diversity-oriented synthesis (DOS)-derived compounds. Of the compounds screened, we obtain hit rates of 12–13 and 0.6% in preselected and naïve libraries, respectively, and identify 52 compounds with exoerythrocytic-stage activity less than 1 μM and having minimal host cell toxicity. Our data demonstrate the ability of this method to identify compounds known to have causal prophylactic activity in both human and animal models of malaria, as well as novel compounds, including some exclusively active against parasite exoerythrocytic stages. PMID:27275010
Macallan, D C; Pocock, M; Robinson, G T; Parker-Williams, J; Bevan, D H
In severe falciparum malaria with high parasitaemia, removal of parasitized erythrocytes is generally considered to be of value as adjunctive therapy in addition to standard chemotherapy. Such removal is commonly achieved by exchange transfusion but this procedure is time-consuming and may be associated with haemodynamic disturbance. Current-generation automated cell-separator hardware and software allows prompt red cell exchange, erythrocytapheresis, in a single continuous-flow isovolaemic procedure. We describe the application of this procedure to 5 cases of severe falciparum malaria in travellers returning to the UK from the tropics. All patients also received quinine and conventional supportive therapy. In all cases, dramatic reduction in parasitaemia was achieved within 2 h with subsequent complete clinical recovery. Erythrocytapheresis has significant advantages over exchange transfusion in terms of speed, efficiency, haemodynamic stability and retention of plasma components such as clotting factors and may thus represent an improvement in adjunctive therapy for severe malaria.
Ouattara, Amed; Laurens, Matthew B
Despite global efforts to control malaria, the illness remains a significant public health threat. Currently, there is no licensed vaccine against malaria, but an efficacious vaccine would represent an important public health tool for successful malaria elimination. Malaria vaccine development continues to be hindered by a poor understanding of antimalarial immunity, a lack of an immune correlate of protection, and the genetic diversity of malaria parasites. Current vaccine development efforts largely target Plasmodium falciparum parasites in the pre-erythrocytic and erythrocytic stages, with some research on transmission-blocking vaccines against asexual stages and vaccines against pregnancy-associated malaria. The leading pre-erythrocytic vaccine candidate is RTS,S, and early results of ongoing Phase 3 testing show overall efficacy of 46% against clinical malaria. The next steps for malaria vaccine development will focus on the design of a product that is efficacious against the highly diverse strains of malaria and the identification of a correlate of protection against disease.
Amangel'diev, K A
from tertian malaria, which is the most dangerous from the epidemiological point of view since the main vectors in Turkmenistan, are highly susceptible to P. vivax infection. The particular dangerous phenomenon is the higher incidence of imported tertian malaria in rural areas where sick people and those who carry the parasite come into close contact with highly susceptible vectors. Thus, the risk that new malaria outbreaks will occur and the disease will become reestablished in the country is very high. It is also influenced by major changes in water use in the country, which have aggravated the mosquito situation. In the area around the Karakum canal and river basins, 17 large reservoirs have been constructed, with very extensive filtration ponds around them, which have become breeding ground's for malaria mosquitoes. There are 1219 water areas without any economic significance in the country, covering a total area of 1054 ha, which require regular treatment with insecticides. With assistance from the WHO European Regional Office, Dr. Guido Sabatinelli in particular, Turkmenistan has developed a plan for preventive malaria control measures for 1999-2001, which has been approved in a decree issued by the Ministry of Health and Medical Industry. The material support received has made it possible to provide large-scale prophylaxis for people who suffered from malaria in 1997-1999, seasonal treatment for people living near the active foci of the disease and interseasonal prophylaxis for people visiting these areas. Seasonal treatment with Dellaguil was made in 4,590 people living in the active foci of malaria infection, and 2,281 fixed-term military personnel belonging to the units stationed in the active foci of malaria infection. In all foci of infection, every person with malaria or carrying the parasite underwent epidemiological investigation and all cases were entered in health clinic records. In 1999, four seminars were held to train 75 specialists from all
HCR, Washington, DC.
This report describes a method to estimate the number of migrant and seasonal farmworkers present in a prescribed area during crop harvest, and to pinpoint areas of high need for health and social services. The collection of health clinic and federal program data on migrant and seasonal farmworkers in Florida, northwestern Ohio, and Maryland's…
Lee, Seonghwan; Song, Kyung-Mi; Jeon, Weejeong; Jo, Hunho; Shim, Yoon-Bo; Ban, Changill
Finding a highly sensitive diagnostic technique for malaria has challenged scientists for the last century. In the present study, we identified versatile single-strand DNA aptamers for Plasmodium lactate dehydrogenase (pLDH), a biomarker for malaria, via the Systematic Evolution of Ligands by EXponential enrichment (SELEX). The pLDH aptamers selectively bound to the target proteins with high sensitivity (K(d)=16.8-49.6 nM). The selected aptamers were characterized using an electrophoretic mobility shift assay, a quartz crystal microbalance, a fluorescence assay, and circular dichroism spectroscopy. We also designed a simple aptasensor using electrochemical impedance spectroscopy; both Plasmodium vivax LDH and Plasmodium falciparum LDH were selectively detected with a detection limit of 1 pM. Furthermore, the pLDH aptasensor clearly distinguished between malaria-positive blood samples of two major species (P. vivax and P. falciparum) and a negative control, indicating that it may be a useful tool for the diagnosis, monitoring, and surveillance of malaria.
Pope, Kevin O.
Malaria is perhaps the most serious human disease problem. It inflicts millions worldwide and is on the rise in many countries where it was once under control. This rise is in part due to the high costs, both economic and environmental, of current control programs. The search for more cost-effective means to combat malaria has focussed attention on new technologies, one of which is remote sensing. Remote sensing has become an important tool in the effort to control a variety of diseases worldwide and malaria is perhaps one of the most promising. This study is part of the malaria control effort in the Central American country of Belize, which has experienced a resurgence of malaria in the last two decades. The proposed project is a feasibility study of the use of Radarsat (and other similar radar systems) to monitor seasonal changes in the breeding sites of the anopheline mosquito, which is responsible for malaria transmission. We propose that spatial and temporal changes in anopheline mosquito production can be predicted by sensing where and when their breeding sites are flooded. Timely knowledge of anopheline mosquito production is a key factor in control efforts. Such knowledge can be used by local control agencies to direct their limited resources to selected areas and time periods when the human population is at greatest risk. Radar is a key sensor in this application because frequent cloud cover during the peak periods of malaria transmission precludes the use of optical sensors.
Camargo-Ayala, Paola Andrea; Cubides, Juan Ricardo; Niño, Carlos Hernando; Camargo, Milena; Rodríguez-Celis, Carlos Arturo; Quiñones, Teódulo; Sánchez-Suárez, Lizeth; Patarroyo, Manuel Elkin; Patarroyo, Manuel Alfonso
Malaria is a worldwide public health problem; parasites from the genus Plasmodium are the aetiological agent for this disease. The parasites are mostly diagnosed by conventional microscopy-based techniques; however, their limitations have led to under-registering the reported prevalence of Plasmodium species. This study has thus been aimed at evaluating the infection and coinfection prevalence of 3 species of Plasmodium spp., in an area of the Colombian Amazon region. Blood samples were taken from 671 symptomatic patients by skin puncture; a nested PCR amplifying the 18S ssRNA region was used on all samples to determine the presence of P. vivax, P. malariae and P. falciparum. Statistical analysis determined infection and coinfection frequency; the association between infection and different factors was established. The results showed that P. vivax was the species having the greatest frequency in the study population (61.4%), followed by P. malariae (43.8%) and P. falciparum (11.8%). The study revealed that 35.8% of the population had coinfection, the P. vivax/P. malariae combination occurring most frequently (28.3%); factors such as age, geographical origin and clinical manifestations were found to be associated with triple-infection. The prevalence reported in this study differed from previous studies in Colombia; the results suggest that diagnosis using conventional techniques could be giving rise to underestimating some Plasmodium spp. species having high circulation rates in Colombia (particularly in the Colombian Amazon region). The present study's results revealed a high prevalence of P. malariae and mixed infections in the population being studied. The results provide relevant information which should facilitate updating the epidemiological panorama and species' distribution so as to include control, prevention and follow-up measures.
Camargo-Ayala, Paola Andrea; Cubides, Juan Ricardo; Niño, Carlos Hernando; Camargo, Milena; Rodríguez-Celis, Carlos Arturo; Quiñones, Teódulo; Sánchez-Suárez, Lizeth; Patarroyo, Manuel Elkin
Malaria is a worldwide public health problem; parasites from the genus Plasmodium are the aetiological agent for this disease. The parasites are mostly diagnosed by conventional microscopy-based techniques; however, their limitations have led to under-registering the reported prevalence of Plasmodium species. This study has thus been aimed at evaluating the infection and coinfection prevalence of 3 species of Plasmodium spp., in an area of the Colombian Amazon region. Blood samples were taken from 671 symptomatic patients by skin puncture; a nested PCR amplifying the 18S ssRNA region was used on all samples to determine the presence of P. vivax, P. malariae and P. falciparum. Statistical analysis determined infection and coinfection frequency; the association between infection and different factors was established. The results showed that P. vivax was the species having the greatest frequency in the study population (61.4%), followed by P. malariae (43.8%) and P. falciparum (11.8%). The study revealed that 35.8% of the population had coinfection, the P. vivax/P. malariae combination occurring most frequently (28.3%); factors such as age, geographical origin and clinical manifestations were found to be associated with triple-infection. The prevalence reported in this study differed from previous studies in Colombia; the results suggest that diagnosis using conventional techniques could be giving rise to underestimating some Plasmodium spp. species having high circulation rates in Colombia (particularly in the Colombian Amazon region). The present study’s results revealed a high prevalence of P. malariae and mixed infections in the population being studied. The results provide relevant information which should facilitate updating the epidemiological panorama and species’ distribution so as to include control, prevention and follow-up measures. PMID:27467587
Imwong, Mallika; Hanchana, Sarun; Malleret, Benoit; Rénia, Laurent; Day, Nicholas P J; Dondorp, Arjen; Nosten, Francois; Snounou, Georges; White, Nicholas J
The epidemiology of malaria in "low-transmission" areas has been underestimated. Molecular detection methods have revealed higher prevalences of malaria than conventional microscopy or rapid diagnostic tests, but these typically evaluate finger-prick capillary blood samples (∼5 μl) and therefore cannot detect parasite densities of <200/ml. Their use underestimates true parasite carriage rates. To characterize the epidemiology of malaria in low-transmission settings and plan elimination strategies, more sensitive quantitative PCR (qPCR) is needed to identify and quantify low-density malaria parasitemias. A highly sensitive "high-volume" quantitative PCR (qPCR) method based on Plasmodium sp. 18S RNA was adapted for blood sample volumes of ≥250 μl and scaled for high throughput. The methods were validated by assessment of the analytical sensitivity and specificity, diagnostic sensitivity, and specificity, efficiency, precision, analytical and diagnostic accuracies, limit of detection, root cause analysis of false positives, and robustness. The high-volume qPCR method based on Plasmodium sp. 18S RNA gave high PCR efficiency of 90 to 105%. Concentrations of parasite DNA from large volumes of blood gave a consistent analytical detection limit (LOD) of 22 parasites/ml (95% CI, 21.79 to 74.9), which is some 2,500 times more sensitive than conventional microscopy and 50 times more sensitive than currently used PCR methods from filter paper blood spots. The diagnostic specificity was 99.75%. Using automated procedures it was possible to process 700 blood samples per week. A very sensitive and specific high-throughput high-volume qPCR method for the detection of low-density parasitemias (>20 parasites/ml) was developed and validated.
Hakre, Shilpa; Masuoka, Penny; Vanzie, Errol; Roberts, Donald R
Background The purposes of this study were to map overall malaria incidence rates from 1989 through 1999 for villages in Belize; to assess the seasonal distribution of malaria incidence by region; and to correlate malaria incidence rates with vegetation cover and rivers in villages, using geographic information system technology. Malaria information on 156 villages was obtained from an electronic database maintained by the Belize National Malaria Control Program. Average annual malaria incidence rates per 1000 population over 10 years were calculated for villages using the 1991 population census as a denominator. Malaria incidence rates were integrated with vegetation cover from a 1995 vegetation map, and with river data from a digital data set. Results Mapping malaria incidence over the 10-year period in the study villages indicated the existence of a spatial pattern: the southern and western areas of Belize had consistently higher rates of malaria than northern areas. Examination of the seasonal distribution of malaria incidence by month over 10 years indicated that a statistically significant difference existed among districts and among months (p < 0.05). Spatial analysis of malaria incidence rates and of vegetation in Belize showed villages with high malaria rates having more broadleaf hill forests, agricultural land, and wetland vegetation types (i.e. SWF-seasonally waterlogged fire-induced shrubland of the plains). Statistical and spatial analyses of malaria incidence and of river distributions in Belize determined the high 10 percentile malaria incidence villages in western and southern Belize to have more rivers within two kilometers of the center of a village and a statistically significant correlation between proximity to rivers and villages (Spearman's γ = -0.23; p < 0.05), especially in Stann Creek District (Spearman's γ = -0.82; p < 0.05). Conclusions Examination of the distribution of malaria during 10 years indicated transmission varied among
Honma, Hajime; Hirai, Makoto; Nakamura, Shota; Hakimi, Hassan; Kawazu, Shin-Ichiro; Palacpac, Nirianne M Q; Hisaeda, Hajime; Matsuoka, Hiroyuki; Kawai, Satoru; Endo, Hiroyoshi; Yasunaga, Teruo; Ohashi, Jun; Mita, Toshihiro; Horii, Toshihiro; Furusawa, Mitsuru; Tanabe, Kazuyuki
Plasmodium falciparum malaria imposes a serious public health concern throughout the tropics. Although genetic tools are principally important to fully investigate malaria parasites, currently available forward and reverse tools are fairly limited. It is expected that parasites with a high mutation rate can readily acquire novel phenotypes/traits; however, they remain an untapped tool for malaria biology. Here, we generated a mutator malaria parasite (hereinafter called a 'malaria mutator'), using site-directed mutagenesis and gene transfection techniques. A mutator Plasmodium berghei line with a defective proofreading 3' → 5' exonuclease activity in DNA polymerase δ (referred to as PbMut) and a control P. berghei line with wild-type DNA polymerase δ (referred to as PbCtl) were maintained by weekly passage in ddY mice for 122 weeks. High-throughput genome sequencing analysis revealed that two PbMut lines had 175-178 mutations and a 86- to 90-fold higher mutation rate than that of a PbCtl line. PbMut, PbCtl, and their parent strain, PbWT, showed similar course of infection. Interestingly, PbMut lost the ability to form gametocytes during serial passages. We believe that the malaria mutator system could provide a novel and useful tool to investigate malaria biology.
Bernabeu, Maria; Danziger, Samuel A.; Avril, Marion; Vaz, Marina; Babar, Prasad H.; Brazier, Andrew J.; Herricks, Thurston; Maki, Jennifer N.; Pereira, Ligia; Mascarenhas, Anjali; Gomes, Edwin; Chery, Laura; Aitchison, John D.; Rathod, Pradipsinh K.; Smith, Joseph D.
The interplay between cellular and molecular determinants that lead to severe malaria in adults is unexplored. Here, we analyzed parasite virulence factors in an infected adult population in India and investigated whether severe malaria isolates impair endothelial protein C receptor (EPCR), a protein involved in coagulation and endothelial barrier permeability. Severe malaria isolates overexpressed specific members of the Plasmodium falciparum var gene/PfEMP1 (P. falciparum erythrocyte membrane protein 1) family that bind EPCR, including DC8 var genes that have previously been linked to severe pediatric malaria. Machine learning analysis revealed that DC6- and DC8-encoding var transcripts in combination with high parasite biomass were the strongest indicators of patient hospitalization and disease severity. We found that DC8 CIDRα1 domains from severe malaria isolates had substantial differences in EPCR binding affinity and blockade activity for its ligand activated protein C. Additionally, even a low level of inhibition exhibited by domains from two cerebral malaria isolates was sufficient to interfere with activated protein C-barrier protective activities in human brain endothelial cells. Our findings demonstrate an interplay between parasite biomass and specific PfEMP1 adhesion types in the development of adult severe malaria, and indicate that low impairment of EPCR function may contribute to parasite virulence. PMID:27185931
Perera, Rushini S.; Ding, Xavier C.; Tully, Frank; Oliver, James; Bright, Nigel; Bell, David; Chiodini, Peter L.; Gonzalez, Iveth J.; Polley, Spencer D.
Background Accurate and efficient detection of sub-microscopic malaria infections is crucial for enabling rapid treatment and interruption of transmission. Commercially available malaria LAMP kits have excellent diagnostic performance, though throughput is limited by the need to prepare samples individually. Here, we evaluate the clinical performance of a newly developed high throughput (HTP) sample processing system for use in conjunction with the Eiken malaria LAMP kit. Methods The HTP system utilised dried blood spots (DBS) and liquid whole blood (WB), with parallel sample processing of 94 samples per run. The system was evaluated using 699 samples of known infection status pre-determined by gold standard nested PCR. Results The sensitivity and specificity of WB-HTP-LAMP was 98.6% (95% CI, 95.7–100), and 99.7% (95% CI, 99.2–100); sensitivity of DBS-HTP-LAMP was 97.1% (95% CI, 93.1–100), and specificity 100% against PCR. At parasite densities greater or equal to 2 parasites/μL, WB and DBS HTP-LAMP showed 100% sensitivity and specificity against PCR. At densities less than 2 p/μL, WB-HTP-LAMP sensitivity was 88.9% (95% CI, 77.1–100) and specificity was 99.7% (95% CI, 99.2–100); sensitivity and specificity of DBS-HTP-LAMP was 77.8% (95% CI, 54.3–99.5) and 100% respectively. Conclusions The HTP-LAMP system is a highly sensitive diagnostic test, with the potential to allow large scale population screening in malaria elimination campaigns. PMID:28166235
Daniels, Rachel; Hamilton, Elizabeth J; Durfee, Katelyn; Ndiaye, Daouda; Wirth, Dyann F; Hartl, Daniel L; Volkman, Sarah K
Despite decades of eradication efforts, malaria remains a global burden. Recent renewed interest in regional elimination and global eradication has been accompanied by increased genomic information about Plasmodium parasite species responsible for malaria, including characteristics of geographical populations as well as variations associated with reduced susceptibility to anti-malarial drugs. One common genetic variation, single-nucleotide polymorphisms (SNPs), offers attractive targets for parasite genotyping. These markers are useful not only for tracking drug resistance markers but also for tracking parasite populations using markers not under drug or other selective pressures. SNP genotyping methods offer the ability to track drug resistance as well as to fingerprint individual parasites for population surveillance, particularly in response to malaria control efforts in regions nearing elimination status. While informative SNPs have been identified that are agnostic to specific genotyping technologies, high-resolution melting (HRM) analysis is particularly suited to field-based studies. Compared to standard fluorescent-probe based methods that require individual SNPs in a single labeled probe and offer at best 10% sensitivity to detect SNPs in samples that contain multiple genomes (polygenomic), HRM offers 2-5% sensitivity. Modifications to HRM, such as blocked probes and asymmetric primer concentrations as well as optimization of amplification annealing temperatures to bias PCR towards amplification of the minor allele, further increase the sensitivity of HRM. While the sensitivity improvement depends on the specific assay, we have increased detection sensitivities to less than 1% of the minor allele. In regions approaching malaria eradication, early detection of emerging or imported drug resistance is essential for prompt response. Similarly, the ability to detect polygenomic infections and differentiate imported parasite types from cryptic local reservoirs
Hidalgo, K; Mouline, K; Mamai, W; Foucreau, N; Dabiré, K R; Bouchereau, A; Simard, F; Renault, D
The mechanisms by which Anopheles gambiae mosquitoes survive the desiccating conditions of the dry season in Africa and are able to readily transmit malaria soon after the rains start remain largely unknown. The desiccation tolerance and resistance of female An. gambiae M and S reared in contrasting environmental conditions reflecting the onset of dry season ("ods") and the rainy season ("rs") was determined by monitoring their survival and body water loss in response to low relative humidity. Furthermore, we investigated the degree to which the physiology of 1-h and 24-h-old females is altered at "ods" by examining and comparing their quantitative metabotypes and proteotypes with conspecifics exposed to "rs" conditions. Results showed that distinct biochemical rearrangements occurred soon after emergence in female mosquitoes that enhance survival and limit water loss under dry conditions. In particular, three amino acids (phenylalanine, tyrosine, and valine) playing a pivotal role in cuticle permeability decreased significantly from the 1-h to 24-h-old females, regardless of the experimental conditions. However, these amino acids were present in higher amounts in 1-h-old female An. gambiae M reared under "ods" whereas no such seasonal difference was reported in S ones. Together with the 1.28- to 2.84-fold increased expression of cuticular proteins 70 and 117, our data suggests that cuticle composition, rigidity and permeability were adjusted at "ods". Increased expression of enzymes involved in glycogenolytic and proteolytic processes were found in both forms at "ods". Moreover, 1-h-old S forms were characterised by elevated amounts of glycogen phosphorylase, isocitrate dehydrogenase, and citrate synthase, suggesting an increase of energetic demand in these females at "ods".
Gil, Luiz Herman Soares; de Lima, Alzemar Alves; Freitag, Elci Marlei; dos Santos, Tatiana Marcondes; do Nascimento Filha, Maria Teixeira; dos Santos Júnior, Alcides Procópio Justiniano; da Silva, Josiane Mendes; Rodrigues, Aline de Freitas; Tada, Mauro Shugiro; Fontes, Cor Jesus Fernandes; Pereira da Silva, Luiz Hildebrando
In children, the Intermittent Preventive Treatment (IPTc), currently called Seasonal Malaria Chemoprevention (SMC), was considered effective on malaria control due to the reduction of its incidence in Papua New Guinea and in some areas with seasonal malaria in Africa. However, the IPT has not been indicated because of its association with drug resistance and for hindering natural immunity development. Thus, we evaluated the alternative IPT impact on malaria incidence in three riverside communities on Madeira River, in the municipality of Porto Velho, RO. We denominate this scheme Selective Intermittent Preventive Treatment (SIPT). The SIPT consists in a weekly dose of two 150 mg chloroquine tablets for 12 weeks, for adults, and an equivalent dose for children, after complete supervised treatment for P. vivax infection. This scheme is recommend by Brazilian Health Ministry to avoid frequent relapses. The clinic parasitological and epidemiological surveillance showed a significant reduction on vivax malaria incidence. The results showed a reduction on relapses and recurrence of malaria after SIPT implementation. The SIPT can be effective on vivax malaria control in localities with high transmission risk in the Brazilian Amazon. PMID:23577276
Background Malaria remains a serious epidemic threat in Mpumalanga Province. In order to appropriately target interventions to achieve substantial reduction in the burden of malaria and ultimately eliminate the disease, there is a need to track progress of malaria control efforts by assessing the time trends and evaluating the impact of current control interventions. This study aimed to assess the changes in the burden of malaria in Mpumalanga Province during the past eight malaria seasons (2001/02 to 2008/09) and whether indoor residual spraying (IRS) and climate variability had an effect on these changes. Methods This is a descriptive retrospective study based on the analysis of secondary malaria surveillance data (cases and deaths) in Mpumalanga Province. Data were extracted from the Integrated Malaria Information System. Time series model (Autoregressive Integrated Moving Average) was used to assess the association between climate and malaria. Results Within the study period, a total of 35,191 cases and 164 deaths due to malaria were notified in Mpumalanga Province. There was a significant decrease in the incidence of malaria from 385 in 2001/02 to 50 cases per 100,000 population in 2008/09 (P < 0.005). The incidence and case fatality (CFR) rates for the study period were 134 cases per 100,000 and 0.54%, respectively. Mortality due to malaria was lower in infants and children (CFR < 0.5%) and higher in those >65 years, with the mean CFR of 2.1% as compared to the national target of 0.5%. A distinct seasonal transmission pattern was found to be significantly related to changes in rainfall patterns (P = 0.007). A notable decline in malaria case notification was observed following apparent scale-up of IRS coverage from 2006/07 to 2008/09 malaria seasons. Conclusions Mpumalanga Province has achieved the goal of reducing malaria morbidity and mortality by over 70%, partly as a result of scale-up of IRS intervention in combination with other control strategies. These
... Laveran and the Discovery of the Malaria Parasite Ross and the Discovery that Mosquitoes Transmit Malaria Parasites ... for work associated with malaria: to Sir Ronald Ross (1902), Charles Louis Alphonse Laveran (1907), Julius Wagner- ...
Background The suppression of indoor malaria transmission requires additional interventions that complement the use of insecticide treated nets (ITNs) and indoor residual spraying (IRS). Previous studies have examined the impact of house structure on malaria transmission in areas of low transmission. This study was conducted in a high transmission setting and presents further evidence about the association between specific house characteristics and the abundance of endophilic malaria vectors. Methods Mosquitoes were sampled using CDC light traps from 72 randomly selected houses in two villages on a monthly basis from 2008 to 2011 in rural Southern Tanzania. Generalized linear models using Poisson distributions were used to analyze the association of house characteristics (eave gaps, wall types, roof types, number of windows, rooms and doors, window screens, house size), number of occupants and ITN usage with mean catches of malaria vectors (An.gambiae s.l. and An. funestus). Results A total of 36490 female An. gambiae s.l. were collected in Namwawala village and 21266 in Idete village. As for An. funestus females, 2268 were collected in Namwawala and 3398 in Idete. Individually, each house factor had a statistically significant impact (p < 0.05) on the mean catches for An. gambiae s.l. but not An. funestus. A multivariate analysis indicated that the combined absence or presence of eaves, treated or untreated bed-nets, the number of house occupants, house size, netting over windows, and roof type were significantly related (p < 0.05) to An.gambiae s.l. and An. funestus house entry in both villages. Conclusions Despite significant reductions in vector density and malaria transmission caused by high coverage of ITNs, high numbers of host-seeking malaria vectors are still found indoors due to house designs that favour mosquito entry. In addition to ITNs and IRS, significant efforts should focus on improving house design to prevent mosquito entry and eliminate
Marsden, P D; Bruce-Chwatt, L J
Cerebral malaria is an acute diffuse encephalopathy associated only with Plasmodium falciparum. It is probably a consequence of the rapid proliferation of the parasites in the body of man in relation to red cell invasion, and results in stagnation of blood flow in cerebralcapillaries with thromobotic occlusion of large numbers of cerebral capillaries. The subsequent cerebral pathology is cerebral infarction with haemorrhage and cerebral oedema. The wide prevalence of P. falciparum in highly endemic areas results in daily challenges to patients from several infected mosquitoes. It is thus important to understand the characteristics of P. falciparum, since this is one of the most important protozoan parasites of man and severe infection from it constitutes one of the few real clinical emergencies in tropical medicine. One of the more important aspects of the practice of medicine in the tropics is to establish a good understanding of the pattern of medical practice in that area. This applies to malaria as well as to other diseases. The neophyte might be somewhat surprised to learn, for example that an experienced colleague who lives in a holoendemic malarious area such as West Africa, sees no cerebral malaria. But the explanation is simple when the doctor concerned has a practice which involves treating adults only. Cerebral malaria is rare in adults, because in highly endemic areas, by the age of 1 year most of the infants in a group under study have already experienced their first falciparum infection. By the time they reach adult life, they have a solid immunity against severe falciparum infections. In fact, "clinical malaria" could occur in such a group under only two circumstances: 1) in pregnancy, a patent infection with P. falciparum might develop, probably due to an IgG drain across the placenta to the foetus;2) in an individual who has constantly taken antimalarials and who may have an immunity at such a low level that when antimalarial therapy is interrupted
Background The first part of this study aimed to develop a model for Anopheles gambiae s.l. with separate parametrization schemes for Anopheles gambiae s.s. and Anopheles arabiensis. The characterizations were constructed based on literature from the past decades. This part of the study is focusing on the model’s ability to separate the mean state of the two species of the An. gambiae complex in Africa. The model is also evaluated with respect to capturing the temporal variability of An. arabiensis in Ethiopia. Before conclusions and guidance based on models can be made, models need to be validated. Methods The model used in this paper is described in part one (Malaria Journal 2013, 12:28). For the validation of the model, a data base of 5,935 points on the presence of An. gambiae s.s. and An. arabiensis was constructed. An additional 992 points were collected on the presence An. gambiae s.l.. These data were used to assess if the model could recreate the spatial distribution of the two species. The dataset is made available in the public domain. This is followed by a case study from Madagascar where the model’s ability to recreate the relative fraction of each species is investigated. In the last section the model’s ability to reproduce the temporal variability of An. arabiensis in Ethiopia is tested. The model was compared with data from four papers, and one field survey covering two years. Results Overall, the model has a realistic representation of seasonal and year to year variability in mosquito densities in Ethiopia. The model is also able to describe the distribution of An. gambiae s.s. and An. arabiensis in sub-Saharan Africa. This implies this model can be used for seasonal and long term predictions of changes in the burden of malaria. Before models can be used to improving human health, or guide which interventions are to be applied where, there is a need to understand the system of interest. Validation is an important part of this process. It is
Hung, Le Q.; Vries, Peter J. de; Giao, Phan T.; Nam, Nguyen V.; Binh, Tran Q.; Chong, M. T.; Quoc, N. T. T. A.; Thanh, T. N.; Hung, L. N.; Kager, P. A.
OBJECTIVE: To follow malaria prospectively in an ethnic minority commune in the south of Viet Nam with high malaria transmission and seasonal fluctuation, during malaria control interventions using insecticide-treated bednets (ITBNs) and early diagnosis and treatment (EDT) of symptomatic patients. METHODS: From 1994 onwards the following interventions were used: distribution of ITBNs to all households with biannual reimpregnation; construction of a health post and appointment of staff trained in microscopic diagnosis and treatment of malaria; regular supply of materials and drugs; annual cross-sectional malaria surveys with treatment of all parasitaemic subjects, and a programme of community involvement and health education. Surveys were held yearly at the end of the rainy season. During the surveys, demographic data were updated. Diagnosis and treatment of malaria were free of charge. Plasmodium falciparum infection was treated with artesunate and P. vivax infection with chloroquine plus primaquine. FINDINGS: The baseline survey in 1994 recorded 716 inhabitants. Of the children under 2 years of age, 37% were parasitaemic; 56% of children aged 2-10 years, and 35% of the remaining population were parasitaemic. P. falciparum accounted for 73-79% of these infections. The respective splenomegaly rates for the above-mentioned age groups were 20%, 56%, and 32%. In 1999, the proportion of parasitaemic subjects was 4%, 7% and 1%, respectively, of which P.falciparum contributed 56%. The splenomegaly rate was 0%, 5% and 2%, respectively. CONCLUSIONS: A combination of ITBNs and EDT, provided free of charge, complemented by annual diagnosis and treatment during malaria surveys and community involvement with health education successfully brought malaria under control. This approach could be applied to other regions in the south of Viet Nam and provides a sound basis for further studies in other areas with different epidemiological patterns of malaria. PMID:12219158
Background The Northern part of Senegal is characterized by a low and seasonal transmission of malaria. However, some Plasmodium falciparum infections and malaria clinical cases are reported during the dry season. This study aims to assess the relationship between IgG antibody (Ab) responses to gSG6-P1 mosquito salivary peptide and the prevalence of P. falciparum infection in children during the dry season in the Senegal River Valley. The positive association of the Ab response to gSG6-P1, as biomarker of human exposure to Anopheles vector bite, and P. falciparum infectious status (uninfected, infected-asymptomatic or infected-symptomatic) will allow considering this biomarker as a potential indicator of P. falciparum infection risk during the dry season. Methods Microscopic examination of thick blood smears was performed in 371 and 310 children at the start (January) and at the end (June) of the dry season, respectively, in order to assess the prevalence of P. falciparum infection. Collected sera were used to evaluate IgG response to gSG6-P1 by ELISA. Association between parasitological and clinical data (infected-asymptomatic or infected-symptomatic) and the anti-gSG6-P1 IgG levels were evaluated during this period. Results The prevalence of P. falciparum infection was very low to moderate according to the studied period and was higher in January (23.5%) compared to June (3.5%). Specific IgG response was also different between uninfected children and asymptomatic carriers of the parasite. Children with P. falciparum infection in the dry season showed higher IgG Ab levels to gSG6-P1 than uninfected children. Conclusions The results strengthen the hypothesis that malaria transmission is maintained during the dry season in an area of low and seasonal transmission. The measurement of IgG responses to gSG6-P1 salivary peptide could be a pertinent indicator of human malaria reservoir or infection risk in this particular epidemiological context. This promising
GIL, Luiz Herman Soares; RODRIGUES, Moreno de Souza; de LIMA, Alzemar Alves; KATSURAGAWA, Tony Hiroshi
We conducted a survey of the malaria vectors in an area where a power line had been constructed, between the municipalities of Porto Velho and Rio Branco, in the states of Rondônia and Acre, respectively. The present paper relates to the results of the survey of Anopheles fauna conducted in the state of Rondônia. Mosquito field collections were performed in six villages along the federal highway BR 364 in the municipality of Porto Velho, namely Porto Velho, Jaci Paraná, Mutum Paraná, Vila Abunã, Vista Alegre do Abunã, and Extrema. Mosquito captures were performed at three distinct sites in each locality during the months of February, July, and October 2011 using a protected human-landing catch method; outdoor and indoor captures were conducted simultaneously at each site for six hours. In the six sampled areas, we captured 2,185 mosquitoes belonging to seven Anopheles species. Of these specimens, 95.1% consisted of Anopheles darlingi, 1.8% An. triannulatus l.s., 1.7% An. deaneorum, 0.8% An. konderi l.s., 0.4 An. braziliensis, 0.1% An. albitarsis l.s., and 0.1% An. benarrochi. An. darlingi was the only species found in all localities; the remaining species occurred in sites with specific characteristics. PMID:26200969
Shin, E-Hyun; Lee, Won-Ja; Lee, Hee Il; Lee, Dong-Kyu; Klein, Terry A
Mosquito surveillance was conducted near the Korean Demilitarized Zone (Paju County, Gyeonggi Province) from April to October, 1999, where malaria cases were reported. Adult mosquito surveillance, using black light and CDC UV light traps, was conducted at five and two sites, respectively. Weekly larval collections were made at five rice paddies located adjacent to the adult collection sites. Anopheles sinensis was the most abundant mosquito of 11 species collected throughout the surveillance period in 1999, comprising 47 - 48% of the total number of mosquitoes collected at cow sheds and residence. At all five sites surveyed by CDC UV light traps, anophelines appeared early in the year (May 3) and were most abundant in the cow sheds followed by the hillside forest, residence, stream/river bank, and were least abundant in rice fields. The population density of the larvae and the adults of An. sinensis increased steadily in June and reached their peaks during the second week of July (mean 112 females/trap/night). The parity rates were higher in July and September, when populations were highest. The probabilities of daily survival of An. sinensis were 0.804 in June to 0.895 in July. Cross-correlation showed a significant relationship between the number of adult anopheline mosquitoes and the number of larvae collected on the previous day, the same day, and also three and seven days later, which may be useful for determining treatment thresholds.
Schaer, Juliane; Perkins, Susan L; Decher, Jan; Leendertz, Fabian H; Fahr, Jakob; Weber, Natalie; Matuschewski, Kai
As the only volant mammals, bats are captivating for their high taxonomic diversity, for their vital roles in ecosystems--particularly as pollinators and insectivores--and, more recently, for their important roles in the maintenance and transmission of zoonotic viral diseases. Genome sequences have identified evidence for a striking expansion of and positive selection in gene families associated with immunity. Bats have also been known to be hosts of malaria parasites for over a century, and as hosts, they possess perhaps the most phylogenetically diverse set of hemosporidian genera and species. To provide a molecular framework for the study of these parasites, we surveyed bats in three remote areas of the Upper Guinean forest ecosystem. We detected four distinct genera of hemosporidian parasites: Plasmodium, Polychromophilus, Nycteria, and Hepatocystis. Intriguingly, the two species of Plasmodium in bats fall within the clade of rodent malaria parasites, indicative of multiple host switches across mammalian orders. We show that Nycteria species form a very distinct phylogenetic group and that Hepatocystis parasites display an unusually high diversity and prevalence in epauletted fruit bats. The diversity and high prevalence of novel lineages of chiropteran hemosporidians underscore the exceptional position of bats among all other mammalian hosts of hemosporidian parasites and support hypotheses of pathogen tolerance consistent with the exceptional immunology of bats.
Schaer, Juliane; Perkins, Susan L.; Decher, Jan; Leendertz, Fabian H.; Fahr, Jakob; Weber, Natalie; Matuschewski, Kai
As the only volant mammals, bats are captivating for their high taxonomic diversity, for their vital roles in ecosystems—particularly as pollinators and insectivores—and, more recently, for their important roles in the maintenance and transmission of zoonotic viral diseases. Genome sequences have identified evidence for a striking expansion of and positive selection in gene families associated with immunity. Bats have also been known to be hosts of malaria parasites for over a century, and as hosts, they possess perhaps the most phylogenetically diverse set of hemosporidian genera and species. To provide a molecular framework for the study of these parasites, we surveyed bats in three remote areas of the Upper Guinean forest ecosystem. We detected four distinct genera of hemosporidian parasites: Plasmodium, Polychromophilus, Nycteria, and Hepatocystis. Intriguingly, the two species of Plasmodium in bats fall within the clade of rodent malaria parasites, indicative of multiple host switches across mammalian orders. We show that Nycteria species form a very distinct phylogenetic group and that Hepatocystis parasites display an unusually high diversity and prevalence in epauletted fruit bats. The diversity and high prevalence of novel lineages of chiropteran hemosporidians underscore the exceptional position of bats among all other mammalian hosts of hemosporidian parasites and support hypotheses of pathogen tolerance consistent with the exceptional immunology of bats. PMID:24101466
Michelsen, Helena Kling; Svensen, Camilla; Reigstad, Marit; Nilssen, Einar Magnus; Pedersen, Torstein
Knowledge on the seasonal timing and composition of pelagic larvae of many benthic invertebrates, referred to as meroplankton, is limited for high-latitude fjords and coastal areas. We investigated the seasonal dynamics of meroplankton in the sub-Arctic Porsangerfjord (70°N), Norway, by examining their seasonal changes in relation to temperature, chlorophyll a and salinity. Samples were collected at two stations between February 2013 and August 2014. We identified 41 meroplanktonic taxa belonging to eight phyla. Multivariate analysis indicated different meroplankton compositions in winter, spring, early summer and late summer. More larvae appeared during spring and summer, forming two peaks in meroplankton abundance. The spring peak was dominated by cirripede nauplii, and late summer peak was dominated by bivalve veligers. Moreover, spring meroplankton were the dominant component in the zooplankton community this season. In winter, low abundances and few meroplanktonic taxa were observed. Timing for a majority of meroplankton correlated with primary production and temperature. The presence of meroplankton in the water column through the whole year and at times dominant in the zooplankton community, suggests that they, in addition to being important for benthic recruitment, may play a role in the pelagic ecosystem as grazers on phytoplankton and as prey for other organisms.
Okitolonda, W; Delacollette, C; Malengreau, M; Henquin, J C
Changes in plasma glucose and insulin concentrations were monitored over 24 hours in 28 African patients receiving quinine intravenously in an average dose of 8.5 mg base/kg over one hour eight hourly for severe malaria. The patients (nine children and 19 adults) were moderately undernourished; none was pregnant or had renal insufficiency. Plasma insulin concentrations rose during the infusion and then declined. Plasma glucose concentrations were decreased at two, three, and four hours after the start of the infusion. Insulin: glucose ratios were raised between half an hour and two hours after the start of the infusion. The three infusions of quinine increased plasma insulin concentrations in a similar way. In nine patients, including four children, plasma glucose concentrations fell below 2.8 mmol/l on one or two occasions. At the time of the hypoglycaemia plasma insulin concentrations were inappropriately high as shown by a consistent and often considerable increase in the insulin:glucose ratio. Hypoglycaemia that may pass unnoticed in comatose patients is thus a common complication of treating severe malaria with quinine, in particular in children. Its high incidence calls for attentive monitoring and preventive measures. PMID:3117315
Chua, Kek Heng; Lim, Siew Chee; Ng, Ching Ching; Lee, Ping Chin; Lim, Yvonne Ai Lian; Lau, Tze Pheng; Chai, Hwa Chia
Molecular detection has overcome limitations of microscopic examination by providing greater sensitivity and specificity in Plasmodium species detection. The objective of the present study was to develop a quantitative real-time polymerase chain reaction coupled with high-resolution melting (qRT-PCR-HRM) assay for rapid, accurate and simultaneous detection of all five human Plasmodium spp. A pair of primers targeted the 18S SSU rRNA gene of the Plasmodium spp. was designed for qRT-PCR-HRM assay development. Analytical sensitivity and specificity of the assay were evaluated. Samples collected from 229 malaria suspected patients recruited from Sabah, Malaysia were screened using the assay and results were compared with data obtained using PlasmoNexTM, a hexaplex PCR system. The qRT-PCR-HRM assay was able to detect and discriminate the five Plasmodium spp. with lowest detection limits of 1–100 copy numbers without nonspecific amplifications. The detection of Plasmodium spp. in clinical samples using this assay also achieved 100% concordance with that obtained using PlasmoNexTM. This indicated that the diagnostic sensitivity and specificity of this assay in Plasmodium spp. detection is comparable with those of PlasmoNexTM. The qRT-PCR-HRM assay is simple, produces results in two hours and enables high-throughput screening. Thus, it is an alternative method for rapid and accurate malaria diagnosis. PMID:26507008
Fairley, Jessica K; Bisanzio, Donal; King, Charles H; Kitron, Uriel; Mungai, Peter; Muchiri, Eric; King, Christopher L; Malhotra, Indu
Results of studies on the associations of maternal helminth infection and malaria-helminth co-infection on birth outcomes have been mixed. A group of 696 pregnant women from the Kwale district in Kenya were recruited and tested for malaria and helminth infection at delivery. Birthweight was documented for 664 infants. A total of 42.7% of the mothers were infected with Plasmodium falciparum, 30.6% with Schistosoma haematobium, 36.2% with filariasis, 31.5% with hookworm, and 5.9% with Trichuris trichiura; co-infection was present in 46.7%. Low birthweight (LBW) (weight < 2,500 grams) was present in 15.4% of the offspring, and 8.3% had a weight z-score ≤ 2 SD below the World Health Organization mean. Only gravida, age, and locale had a significant association with LBW. The high prevalence of maternal infection coupled with a higher than expected percentage of LBW highlight a need for further investigation of the association of maternal co-infection with LBW.
Plouffe, David M.; Wree, Melanie; Du, Alan Y.; Meister, Stephan; Li, Fengwu; Patra, Kailash; Lubar, Aristea; Okitsu, Shinji L.; Flannery, Erika L.; Kato, Nobutaka; Tanaseichuk, Olga; Comer, Eamon; Zhou, Bin; Kuhen, Kelli; Zhou, Yingyao; Leroy, Didier; Schreiber, Stuart L.; Scherer, Christina A.; Vinetz, Joseph; Winzeler, Elizabeth A.
Summary Preventing transmission is an important element of malaria control. However, most of the current available methods to assay for malaria transmission blocking are relatively low throughput and cannot be applied to large chemical libraries. We have developed a high-throughput and cost-effective assay, the Saponin-lysis Sexual Stage Assay (SaLSSA), for identifying small molecules with transmission-blocking capacity. SaLSSA analysis of 13,983 unique compounds uncovered that >90% of well-characterized antimalarials, including endoperoxides and 4-aminoquinolines, as well as compounds active against asexual blood stages, lost most of their killing activity when parasites developed into metabolically quiescent stage V gametocytes. On the other hand, we identified compounds with consistent low nanomolar transmission-blocking activity, some of which showed cross-reactivity against asexual blood and liver stages. The data clearly emphasize substantial physiological differences between sexual and asexual parasites and provide a tool and starting points for the discovery and development of transmission-blocking drugs. PMID:26749441
Plouffe, David M; Wree, Melanie; Du, Alan Y; Meister, Stephan; Li, Fengwu; Patra, Kailash; Lubar, Aristea; Okitsu, Shinji L; Flannery, Erika L; Kato, Nobutaka; Tanaseichuk, Olga; Comer, Eamon; Zhou, Bin; Kuhen, Kelli; Zhou, Yingyao; Leroy, Didier; Schreiber, Stuart L; Scherer, Christina A; Vinetz, Joseph; Winzeler, Elizabeth A
Preventing transmission is an important element of malaria control. However, most of the current available methods to assay for malaria transmission blocking are relatively low throughput and cannot be applied to large chemical libraries. We have developed a high-throughput and cost-effective assay, the Saponin-lysis Sexual Stage Assay (SaLSSA), for identifying small molecules with transmission-blocking capacity. SaLSSA analysis of 13,983 unique compounds uncovered that >90% of well-characterized antimalarials, including endoperoxides and 4-aminoquinolines, as well as compounds active against asexual blood stages, lost most of their killing activity when parasites developed into metabolically quiescent stage V gametocytes. On the other hand, we identified compounds with consistent low nanomolar transmission-blocking activity, some of which showed cross-reactivity against asexual blood and liver stages. The data clearly emphasize substantial physiological differences between sexual and asexual parasites and provide a tool and starting points for the discovery and development of transmission-blocking drugs.
Krupka, Malkie; Williams, Chris; Seydel, Karl; Taylor, Terrie E.; Van de Peer, Yves; Regev, Aviv; Wirth, Dyann
Background In the past decade, estimates of malaria infections have dropped from 500 million to 225 million per year; likewise, mortality rates have dropped from 3 million to 791,000 per year. However, approximately 90% of these deaths continue to occur in sub-Saharan Africa, and 85% involve children less than 5 years of age. Malaria mortality in children generally results from one or more of the following clinical syndromes: severe anemia, acidosis, and cerebral malaria. Although much is known about the clinical and pathological manifestations of CM, insights into the biology of the malaria parasite, specifically transcription during this manifestation of severe infection, are lacking. Methods and Findings We collected peripheral blood from children meeting the clinical case definition of cerebral malaria from a cohort in Malawi, examined the patients for the presence or absence of malaria retinopathy, and performed whole genome transcriptional profiling for Plasmodium falciparum using a custom designed Affymetrix array. We identified two distinct physiological states that showed highly significant association with the level of parasitemia. We compared both groups of Malawi expression profiles with our previously acquired ex vivo expression profiles of parasites derived from infected patients with mild disease; a large collection of in vitro Plasmodium falciparum life cycle gene expression profiles; and an extensively annotated compendium of expression data from Saccharomyces cerevisiae. The high parasitemia patient group demonstrated a unique biology with elevated expression of Hrd1, a member of endoplasmic reticulum-associated protein degradation system. Conclusions The presence of a unique high parasitemia state may be indicative of the parasite biology of the clinically recognized hyperparasitemic severe disease syndrome. PMID:22815802
Ouattara, Amed; Laurens, Matthew B.
Despite global efforts to control malaria, the illness remains a significant public health threat. Currently, there is no licensed vaccine against malaria, but an efficacious vaccine would represent an important public health tool for successful malaria elimination. Malaria vaccine development continues to be hindered by a poor understanding of antimalarial immunity, a lack of an immune correlate of protection, and the genetic diversity of malaria parasites. Current vaccine development efforts largely target Plasmodium falciparum parasites in the pre-erythrocytic and erythrocytic stages, with some research on transmission-blocking vaccines against asexual stages and vaccines against pregnancy-associated malaria. The leading pre-erythrocytic vaccine candidate is RTS,S, and early results of ongoing Phase 3 testing show overall efficacy of 46% against clinical malaria. The next steps for malaria vaccine development will focus on the design of a product that is efficacious against the highly diverse strains of malaria and the identification of a correlate of protection against disease. PMID:25452593
Lampah, Daniel A.; Simpson, Julie A.; Kenangalem, Enny; Sugiarto, Paulus; Anstey, Nicholas M.; Poespoprodjo, Jeanne Rini; Price, Ric N.
Background Plasmodium malariae is a slow-growing parasite with a wide geographic distribution. Although generally regarded as a benign cause of malaria, it has been associated with nephrotic syndrome, particularly in young children, and can persist in the host for years. Morbidity associated with P. malariae infection has received relatively little attention, and the risk of P. malariae-associated nephrotic syndrome is unknown. Methodology/Principal Findings We used data from a very large hospital-based surveillance system incorporating information on clinical diagnoses, blood cell parameters and treatment to describe the demographic distribution, morbidity and mortality associated with P. malariae infection in southern Papua, Indonesia. Between April 2004 and December 2013 there were 1,054,674 patient presentations to Mitra Masyarakat Hospital of which 196,380 (18.6%) were associated with malaria and 5,097 were with P. malariae infection (constituting 2.6% of all malaria cases). The proportion of malaria cases attributable to P. malariae increased with age from 0.9% for patients under one year old to 3.1% for patients older than 15 years. Overall, 8.5% of patients with P. malariae infection required admission to hospital and the median length of stay for these patients was 2.5 days (Interquartile Range: 2.0–4.0 days). Patients with P. malariae infection had a lower mean hemoglobin concentration (9.0g/dL) than patients with P. falciparum (9.5g/dL), P. vivax (9.6g/dL) and mixed species infections (9.3g/dL). There were four cases of nephrotic syndrome recorded in patients with P. malariae infection, three of which were in children younger than 5 years old, giving a risk in this age group of 0.47% (95% Confidence Interval; 0.10% to 1.4%). Overall, 2.4% (n = 16) of patients hospitalized with P. malariae infection subsequently died in hospital, similar to the proportions for the other endemic Plasmodium species (range: 0% for P. ovale to 1.6% for P. falciparum
Dantur Juri, María J; Zaidenberg, Mario; Claps, Guillermo L; Santana, Mirta; Almirón, Walter R
Background Malaria is one of the most important tropical diseases that affects people globally. The influence of environmental conditions in the patterns of temporal distribution of malaria vectors and the disease has been studied in different countries. In the present study, ecological aspects of the malaria vector Anopheles (Anopheles) pseudopunctipennis and their relationship with climatic variables, as well as the seasonality of malaria cases, were studied in two localities, El Oculto and Aguas Blancas, in north-western Argentina. Methods The fluctuation of An. pseudopunctipennis and the malaria cases distribution was analysed with Random Effect Poisson Regression. This analysis takes into account the effect of each climatic variable on the abundance of both vector and malaria cases, giving as results predicted values named Incidence Rate Radio. Results The number of specimens collected in El Oculto and Aguas Blancas was 4224 (88.07%) and 572 (11.93%), respectively. In El Oculto no marked seasonality was found, different from Aguas Blancas, where high abundance was detected at the end of spring and the beginning of summer. The maximum mean temperature affected the An. pseudopunctipennis fluctuation in El Oculto and Aguas Blancas. When considering the relationship between the number of malaria cases and the climatic variables in El Oculto, maximum mean temperature and accumulated rainfall were significant, in contrast with Aguas Blancas, where mean temperature and humidity showed a closer relationship to the fluctuation in the disease. Conclusion The temporal distribution patterns of An. pseudopunctipennis vary in both localities, but spring appears as the season with better conditions for mosquito development. Maximum mean temperature was the most important variable in both localities. Malaria cases were influenced by the maximum mean temperature in El Oculto, while the mean temperature and humidity were significant in Aguas Blancas. In Aguas Blancas peaks of
Agwu, E.; Ihongbe, J.C.; Okogun, G.R.A.; Inyang, N.J.
This survey was designed to determine the prevalence of Plasmodium falciparum and Salmonella Typhi among febrile HIV/AIDS patients in Ekpoma. Malaria and typhoid risk factors in Ekpoma included occupation, poor health facilities and poor sanitation. Malaria and typhoid are highly prevalent among Ekpoma HIV/AIDS patients. PMID:24031367
Background Long-lasting insecticidal nets (LLINs) are an important tool for controlling malaria. Much attention has been devoted to determine both the effect of LLINs on the reduction of Plasmodium infection rate and on clinically-confirmed malaria cases in sub-Saharan Africa. We carried out an epidemiological study to investigate whether LLINs impact on Plasmodium prevalence rate and the proportion of clinically-confirmed malaria cases, in five villages in the district of Toumodi, central Côte d'Ivoire. Methods From April 2007 to November 2008, a community-based malaria control programme was implemented in the study villages, which involved large-scale distribution of LLINs, and training and sensitization activities within the community. We determined the effect of this programme on Plasmodium prevalence rate, clinically-confirmed malaria cases and proportion of high parasitaemia rates in children aged 6-59 months through a series of cross-sectional surveys starting in April 2007 and repeated once every 6 months. Results We observed a significant decrease in the mean P. falciparum prevalence rate from April 2007 to April 2008 (p = 0.029). An opposite trend was observed from November 2007 to November 2008 when P. falciparum prevalence rate increased significantly (p = 0.003). Highly significant decreases in the proportions of clinical malaria cases were observed between April 2007 and April 2008 (p < 0.001), and between November 2007 and November 2008 (p = 0.001). Conclusions Large-scale distribution of LLINs, accompanied by training and sensitization activities, significantly reduced Plasmodium prevalence rates among young children in the first year of the project, whereas overall clinical malaria rates dropped over the entire 18-month project period. A decrease in community motivation to sleep under bed nets, perhaps along with changing patterns of malaria transmission, might explain the observed increase in the Plasmodium prevalence rate between November 2007
George, Phillip; Sharakhova, Maria V.; Sharakhov, Igor V.
Cytogenetic and physical maps are indispensible for precise assembly of genome sequences, functional characterization of chromosomal regions, and population genetic and taxonomic studies. We have created a new cytogenetic map for Anopheles gambiae by using a high-pressure squash technique that increases overall band clarity. To link chromosomal regions to the genome sequence, we attached genome coordinates, based on 302 markers of BAC, cDNA clones, and PCR-amplified gene fragments, to the chromosomal bands and interbands at approximately a 0.5-1 Mb interval. In addition, we placed the breakpoints of seven common polymorphic inversions on the map and described the chromosomal landmarks for the arm and inversion identification. The map's improved resolution can be used to further enhance physical mapping, improve genome assembly, and stimulate epigenomic studies of malaria vectors. PMID:20609021
Carme, B; Yombi, B; Plassart, H
The diagnosis of malaria attack in regions for highly endemic P. falciparum is difficult. It is more so since the wide use of antimalarials by the infected populations and the spread of drug resistance. A positive test is not evidence for a malarial attack since in certain schools, in both rural regions and in some districts of big towns, over 3/4 of the children attending school are carriers of Plasmodium. On the other hand, true attacks, even severe forms, can occur without evidence of parasitaemia. The parasitic load is thus an important factor but the following must be taken into consideration: age, level of immunity, the extent of transmission and whether if is continuous or not, self medication and the initial systematic treatments, the possibility of drug resistance, ... The difficulties are illustrated by data collected in the Congo.
Caminade, Cyril; Kovats, Sari; Rocklov, Joacim; Tompkins, Adrian M; Morse, Andrew P; Colón-González, Felipe J; Stenlund, Hans; Martens, Pim; Lloyd, Simon J
Malaria is an important disease that has a global distribution and significant health burden. The spatial limits of its distribution and seasonal activity are sensitive to climate factors, as well as the local capacity to control the disease. Malaria is also one of the few health outcomes that has been modeled by more than one research group and can therefore facilitate the first model intercomparison for health impacts under a future with climate change. We used bias-corrected temperature and rainfall simulations from the Coupled Model Intercomparison Project Phase 5 climate models to compare the metrics of five statistical and dynamical malaria impact models for three future time periods (2030s, 2050s, and 2080s). We evaluated three malaria outcome metrics at global and regional levels: climate suitability, additional population at risk and additional person-months at risk across the model outputs. The malaria projections were based on five different global climate models, each run under four emission scenarios (Representative Concentration Pathways, RCPs) and a single population projection. We also investigated the modeling uncertainty associated with future projections of populations at risk for malaria owing to climate change. Our findings show an overall global net increase in climate suitability and a net increase in the population at risk, but with large uncertainties. The model outputs indicate a net increase in the annual person-months at risk when comparing from RCP2.6 to RCP8.5 from the 2050s to the 2080s. The malaria outcome metrics were highly sensitive to the choice of malaria impact model, especially over the epidemic fringes of the malaria distribution.
Caminade, Cyril; Kovats, Sari; Rocklov, Joacim; Tompkins, Adrian M.; Morse, Andrew P.; Colón-González, Felipe J.; Stenlund, Hans; Martens, Pim; Lloyd, Simon J.
Malaria is an important disease that has a global distribution and significant health burden. The spatial limits of its distribution and seasonal activity are sensitive to climate factors, as well as the local capacity to control the disease. Malaria is also one of the few health outcomes that has been modeled by more than one research group and can therefore facilitate the first model intercomparison for health impacts under a future with climate change. We used bias-corrected temperature and rainfall simulations from the Coupled Model Intercomparison Project Phase 5 climate models to compare the metrics of five statistical and dynamical malaria impact models for three future time periods (2030s, 2050s, and 2080s). We evaluated three malaria outcome metrics at global and regional levels: climate suitability, additional population at risk and additional person-months at risk across the model outputs. The malaria projections were based on five different global climate models, each run under four emission scenarios (Representative Concentration Pathways, RCPs) and a single population projection. We also investigated the modeling uncertainty associated with future projections of populations at risk for malaria owing to climate change. Our findings show an overall global net increase in climate suitability and a net increase in the population at risk, but with large uncertainties. The model outputs indicate a net increase in the annual person-months at risk when comparing from RCP2.6 to RCP8.5 from the 2050s to the 2080s. The malaria outcome metrics were highly sensitive to the choice of malaria impact model, especially over the epidemic fringes of the malaria distribution. PMID:24596427
Background The Solomon Islands National Malaria Programme is currently focused on intensified control and progressive elimination. Recent control efforts in Isabel Province have reduced their malaria incidence to 2.6/1,000 population in 2009  whereas most neighbouring provinces have much higher incidences. A malaria surveillance-response system that involves testing all travellers entering Isabel Province using rapid diagnostic tests (RDT) to prevent cases being imported had been proposed by local health authorities. This study provides information on the feasibility and acceptability of implementing a new approach of surveillance and response in the context of low levels of indigenous malaria transmission in Isabel Province. Methods A total of 13 focus group discussions (FGD) and 22 key informant interviews (KII) were conducted in Isabel Province, Solomon Islands. Key topics included: the travel patterns of people to, from and within Isabel Province; the acceptability, community perceptions, attitudes and suggestions towards the proposed surveillance programme; and management of suspected malaria cases. This information was triangulated with data obtained from port authorities, airlines and passenger ships travelling to and from Isabel Province in the preceding two years. Results Travel within Isabel Province and to and from other provinces is common with marked seasonality. The majority of inter-provincial travel is done on scheduled public transport; namely passenger ships and aircrafts. In Isabel Province there is a healthy community spirit as well as high concern regarding malaria and its importation and there is currently effective malaria passive case detection and management. Conducting malaria screening at ports and airports would be acceptable to the community. Conclusion A robust surveillance-response system is essential when moving towards malaria elimination. Many factors contribute positively towards the feasibility of an RDT based malaria
Bruce, Marian C.; Macheso, Allan; Kelly-Hope, Louise A.; Nkhoma, Standwell; McConnachie, Alex; Molyneux, Malcolm E.
Background In malaria endemic regions people are commonly infected with multiple species of malaria parasites but the clinical impact of these Plasmodium co-infections is unclear. Differences in transmission seasonality and transmission intensity between endemic regions have been suggested as important factors in determining the effect of multiple species co-infections. Principal Findings In order to investigate the impact of multiple-species infections on clinical measures of malaria we carried out a cross-sectional community survey in Malawi, in 2002. We collected clinical and parasitological data from 2918 participants aged >6 months, and applied a questionnaire to measure malaria morbidity. We examined the effect of transmission seasonality and intensity on fever, history of fever, haemoglobin concentration ([Hb]) and parasite density, by comparing three regions: perennial transmission (PT), high intensity seasonal transmission (HIST) and low intensity seasonal transmission (LIST). These regions were defined using multi-level modelling of PCR prevalence data and spatial and geo-climatic measures. The three Plasmodium species (P. falciparum, P. malariae and P. ovale) were randomly distributed amongst all children but not adults in the LIST and PT regions. Mean parasite density in children was lower in the HIST compared with the other two regions. Mixed species infections had lower mean parasite density compared with single species infections in the PT region. Fever rates were similar between transmission regions and were unaffected by mixed species infections. A history of fever was associated with single species infections but only in the HIST region. Reduced mean [Hb] and increased anaemia was associated with perennial transmission compared to seasonal transmission. Children with mixed species infections had higher [Hb] in the HIST region. Conclusions Our study suggests that the interaction of Plasmodium co-infecting species can have protective effects against
Lapointe, Dennis A; Atkinson, Carter T; Samuel, Michael D
Avian malaria is a worldwide mosquito-borne disease caused by Plasmodium parasites. These parasites occur in many avian species but primarily affect passerine birds that have not evolved with the parasite. Host pathogenicity, fitness, and population impacts are poorly understood. In contrast to continental species, introduced avian malaria poses a substantial threat to naive birds on Hawaii, the Galapagos, and other archipelagoes. In Hawaii, transmission is maintained by susceptible native birds, competence and abundance of mosquitoes, and a disease reservoir of chronically infected native birds. Although vector habitat and avian communities determine the geographic distribution of disease, climate drives transmission patterns ranging from continuous high infection in warm lowland forests, seasonal infection in midelevation forests, and disease-free refugia in cool high-elevation forests. Global warming is expected to increase the occurrence, distribution, and intensity of avian malaria across this elevational gradient and threaten high-elevation refugia, which is the key to survival of many susceptible Hawaiian birds. Increased temperatures may have already increased global avian malaria prevalence and contributed to an emergence of disease in New Zealand.
LaPointe, Dennis A.; Atkinson, Carter T.; Samuel, Michael D.
Avian malaria is a worldwide mosquito-borne disease caused by Plasmodium parasites. These parasites occur in many avian species but primarily affect passerine birds that have not evolved with the parasite. Host pathogenicity, fitness, and population impacts are poorly understood. In contrast to continental species, introduced avian malaria poses a substantial threat to naive birds on Hawaii, the Galapagos, and other archipelagoes. In Hawaii, transmission is maintained by susceptible native birds, competence and abundance of mosquitoes, and a disease reservoir of chronically infected native birds. Although vector habitat and avian communities determine the geographic distribution of disease, climate drives transmission patterns ranging from continuous high infection in warm lowland forests, seasonal infection in midelevation forests, and disease-free refugia in cool high-elevation forests. Global warming is expected to increase the occurrence, distribution, and intensity of avian malaria across this elevational gradient and threaten high-elevation refugia, which is the key to survival of many susceptible Hawaiian birds. Increased temperatures may have already increased global avian malaria prevalence and contributed to an emergence of disease in New Zealand.
Laneri, Karina; Paul, Richard E.; Tall, Adama; Faye, Joseph; Diene-Sarr, Fatoumata; Sokhna, Cheikh; Trape, Jean-François; Rodó, Xavier
Assessing the influence of climate on the incidence of Plasmodium falciparum malaria worldwide and how it might impact local malaria dynamics is complex and extrapolation to other settings or future times is controversial. This is especially true in the light of the particularities of the short- and long-term immune responses to infection. In sites of epidemic malaria transmission, it is widely accepted that climate plays an important role in driving malaria outbreaks. However, little is known about the role of climate in endemic settings where clinical immunity develops early in life. To disentangle these differences among high- and low-transmission settings we applied a dynamical model to two unique adjacent cohorts of mesoendemic seasonal and holoendemic perennial malaria transmission in Senegal followed for two decades, recording daily P. falciparum cases. As both cohorts are subject to similar meteorological conditions, we were able to analyze the relevance of different immunological mechanisms compared with climatic forcing in malaria transmission. Transmission was first modeled by using similarly unique datasets of entomological inoculation rate. A stochastic nonlinear human–mosquito model that includes rainfall and temperature covariates, drug treatment periods, and population variability is capable of simulating the complete dynamics of reported malaria cases for both villages. We found that under moderate transmission intensity climate is crucial; however, under high endemicity the development of clinical immunity buffers any effect of climate. Our models open the possibility of forecasting malaria from climate in endemic regions but only after accounting for the interaction between climate and immunity. PMID:26124134
Laneri, Karina; Paul, Richard E; Tall, Adama; Faye, Joseph; Diene-Sarr, Fatoumata; Sokhna, Cheikh; Trape, Jean-François; Rodó, Xavier
Assessing the influence of climate on the incidence of Plasmodium falciparum malaria worldwide and how it might impact local malaria dynamics is complex and extrapolation to other settings or future times is controversial. This is especially true in the light of the particularities of the short- and long-term immune responses to infection. In sites of epidemic malaria transmission, it is widely accepted that climate plays an important role in driving malaria outbreaks. However, little is known about the role of climate in endemic settings where clinical immunity develops early in life. To disentangle these differences among high- and low-transmission settings we applied a dynamical model to two unique adjacent cohorts of mesoendemic seasonal and holoendemic perennial malaria transmission in Senegal followed for two decades, recording daily P. falciparum cases. As both cohorts are subject to similar meteorological conditions, we were able to analyze the relevance of different immunological mechanisms compared with climatic forcing in malaria transmission. Transmission was first modeled by using similarly unique datasets of entomological inoculation rate. A stochastic nonlinear human-mosquito model that includes rainfall and temperature covariates, drug treatment periods, and population variability is capable of simulating the complete dynamics of reported malaria cases for both villages. We found that under moderate transmission intensity climate is crucial; however, under high endemicity the development of clinical immunity buffers any effect of climate. Our models open the possibility of forecasting malaria from climate in endemic regions but only after accounting for the interaction between climate and immunity.
Roytman, Leonid; Nizamuddin, Mohammad; Akhand, Kawsar; Kogan, Felix; Goldberg, Mitchell
A better understanding of the relationship between satellites observed vegetation health, and malaria epidemics could help mitigate the worldwide increase in incidence of mosquito-transmitted diseases. This research investigates last 17- years association between vegetation health (condition) index and malaria transmission in Bikaner, Rajasthan in India an arid and hot summer area. The vegetation health (condition) index, derived from a combination of Advanced Very High Resolution Radiometer (AVHRR) based Normalized Difference Vegetation Index (NDVI) and 10-μm to 11-μm thermal radiances, was designed for monitoring moisture and thermal impacts on vegetation health. We demonstrate that thermal condition is more sensitive to malaria transmission with different seasonal malaria activities. The weekly VH indices were correlated with the epidemiological data. A good correlation was found between malaria cases and Temperature Condition Index (TCI) one at least two months earlier than the malaria transmission season. Following the results of correlation analysis, Principal Component Regression (PCR) method was used to construct a model of less than 10% error to predict malaria as a function of the TCI.
Perez-Guaita, David; Andrew, Dean; Heraud, Philip; Beeson, James; Anderson, David; Richards, Jack; Wood, Bayden R
New highly sensitive tools for malaria diagnostics are urgently needed to enable the detection of infection in asymptomatic carriers and patients with low parasitemia. In pursuit of a highly sensitive diagnostic tool that can identify parasite infections at the single cell level, we have been exploring Fourier transform infrared (FTIR) microscopy using a Focal Plane Array (FPA) imaging detector. Here we report for the first time the application of a new optic configuration developed by Agilent that incorporates 25× condenser and objective Cassegrain optics with a high numerical aperture (NA = 0.81) along with additional high magnification optics within the microscope to provide 0.66 micron pixel resolution (total IR system magnification of 61×) to diagnose malaria parasites at the single cell level on a conventional glass microscope slide. The high quality images clearly resolve the parasite's digestive vacuole demonstrating sub-cellular resolution using this approach. Moreover, we have developed an algorithm that first detects the cells in the infrared image, and secondly extracts the average spectrum. The average spectrum is then run through a model based on Partial Least Squares-Discriminant Analysis (PLS-DA), which diagnoses unequivocally the infected from normal cells. The high quality images, and the fact this measurement can be achieved without a synchrotron source on a conventional glass slide, shows promise as a potential gold standard for malaria detection at the single cell level.
Céspedes, Nora; Vallejo, Andrés; Arévalo-Herrera, Myriam; Herrera, Sócrates
Malaria is a disease induced by parasites of the Plasmodium genus, which are transmitted by Anopheles mosquitoes and represents a great socio-economic burden Worldwide. Plasmodium vivax is the second species of malaria Worldwide, but it is the most prevalent in Latin America and other regions of the planet. It is currently considered that vaccines represent a cost-effective strategy for controlling transmissible diseases and could complement other malaria control measures; however, the chemical and immunological complexity of the parasite has hindered development of effective vaccines. Recent availability of several genomes of Plasmodium species, as well as bioinformatic tools are allowing the selection of large numbers of proteins and analysis of their immune potential. Herein, we review recently developed strategies for discovery of novel antigens with potential for malaria vaccine development.
Dao, A; Yaro, A S; Diallo, M; Timbiné, S; Huestis, D L; Kassogué, Y; Traoré, A I; Sanogo, Z L; Samaké, D; Lehmann, T
During the long Sahelian dry season, mosquito vectors of malaria are expected to perish when no larval sites are available; yet, days after the first rains, mosquitoes reappear in large numbers. How these vectors persist over the 3-6-month long dry season has not been resolved, despite extensive research for over a century. Hypotheses for vector persistence include dry-season diapause (aestivation) and long-distance migration (LDM); both are facets of vector biology that have been highly controversial owing to lack of concrete evidence. Here we show that certain species persist by a form of aestivation, while others engage in LDM. Using time-series analyses, the seasonal cycles of Anopheles coluzzii, Anopheles gambiae sensu stricto (s.s.), and Anopheles arabiensis were estimated, and their effects were found to be significant, stable and highly species-specific. Contrary to all expectations, the most complex dynamics occurred during the dry season, when the density of A. coluzzii fluctuated markedly, peaking when migration would seem highly unlikely, whereas A. gambiae s.s. was undetected. The population growth of A. coluzzii followed the first rains closely, consistent with aestivation, whereas the growth phase of both A. gambiae s.s. and A. arabiensis lagged by two months. Such a delay is incompatible with local persistence, but fits LDM. Surviving the long dry season in situ allows A. coluzzii to predominate and form the primary force of malaria transmission. Our results reveal profound ecological divergence between A. coluzzii and A. gambiae s.s., whose standing as distinct species has been challenged, and suggest that climate is one of the selective pressures that led to their speciation. Incorporating vector dormancy and LDM is key to predicting shifts in the range of malaria due to global climate change, and to the elimination of malaria from Africa.
Taylor, Steve M; Juliano, Jonathan J; Trottman, Paul A; Griffin, Jennifer B; Landis, Sarah H; Kitsa, Paluku; Tshefu, Antoinette K; Meshnick, Steven R
Molecular assays can provide critical information for malaria diagnosis, speciation, and drug resistance, but their cost and resource requirements limit their application to clinical malaria studies. This study describes the application of a resource-conserving testing algorithm employing sample pooling for real-time PCR assays for malaria in a cohort of 182 pregnant women in Kinshasa. A total of 1,268 peripheral blood samples were collected during the study. Using a real-time PCR assay that detects all Plasmodium species, microscopy-positive samples were amplified individually; the microscopy-negative samples were amplified after pooling the genomic DNA (gDNA) of four samples prior to testing. Of 176 microscopy-positive samples, 74 were positive by the real-time PCR assay; the 1,092 microscopy-negative samples were initially amplified in 293 pools, and subsequently, 35 samples were real-time PCR positive (3%). With the real-time PCR result as the referent standard, microscopy was 67.9% sensitive (95% confidence interval [CI], 58.3% to 76.5%) and 91.2% specific (95% CI, 89.4% to 92.8%) for malaria. In total, we detected 109 parasitemias by real-time PCR and, by pooling samples, obviated over 50% of reactions and halved the cost of testing. Our study highlights both substantial discordance between malaria diagnostics and the utility and parsimony of employing a sample pooling strategy for molecular diagnostics in clinical and epidemiologic malaria studies.
Carmona-Fonseca, Jaime; Alvarez, Gonzalo; Maestre, Amanda
Primaquine (PQ) is recommended to prevent relapses in patients with Plasmodium vivax malaria infection. However, treatment with PQ causes methemoglobinemia. In this study, we measured the methemoglobin (MetHB) levels in three groups of subjects who received PQ treatment at 0.58, 0.83, or 1.17 mg/kg/d. A total of 112 subjects were studied. MetHB levels were detected at > or = 4% in 46-50% 1 day after PQ treatment in all three groups and 4-9% of subjects had MetHB levels > or = 4% 15 days after treatment. Only subjects receiving the highest doses of PQ had mild and brief adverse events, and 17% of them were associated with treatment. We conclude that when PQ is administered under certain conditions (i.e., normal glucose-6-phosphate dehydrogenase activity, in non-pregnant subjects and with a light meal), daily doses as high as 1.17 mg/kg do not represent a serious risk of high MetHB levels to patients.
Ackleh, Azmy S; Ma, Baoling; Thibodeaux, Jeremy J
We develop a second-order high-resolution finite difference scheme to approximate the solution of a mathematical model describing the within-host dynamics of malaria infection. The model consists of two nonlinear partial differential equations coupled with three nonlinear ordinary differential equations. Convergence of the numerical method to the unique weak solution with bounded total variation is proved. Numerical simulations demonstrating the achievement of the designed accuracy are presented.
Lucantoni, Leonardo; Silvestrini, Francesco; Signore, Michele; Siciliano, Giulia; Eldering, Maarten; Dechering, Koen J.; Avery, Vicky M.; Alano, Pietro
Plasmodium falciparum gametocytes, specifically the mature stages, are the only malaria parasite stage in humans transmissible to the mosquito vector. Anti-malarial drugs capable of killing these forms are considered essential for the eradication of malaria and tools allowing the screening of large compound libraries with high predictive power are needed to identify new candidates. As gametocytes are not a replicative stage it is difficult to apply the same drug screening methods used for asexual stages. Here we propose an assay, based on high content imaging, combining “classic” gametocyte viability readout based on gametocyte counts with a functional viability readout, based on gametocyte activation and the discrimination of the typical gamete spherical morphology. This simple and rapid assay has been miniaturized to a 384-well format using acridine orange staining of wild type P. falciparum 3D7A sexual forms, and was validated by screening reference antimalarial drugs and the MMV Malaria Box. The assay demonstrated excellent robustness and ability to identify quality hits with high likelihood of confirmation of transmission reducing activity in subsequent mosquito membrane feeding assays. PMID:26553647
Xu, Xin; Zhou, Guofa; Wang, Ying; Hu, Yue; Ruan, Yonghua; Fan, Qi
To identify township-level high-risk foci of malaria transmission in Yunnan Province, China, along the international border, we retrospectively reviewed data collected in hospitals and clinics of 58 townships in 4 counties during 2011–2013. We analyzed spatiotemporal distribution, especially hot spots of confirmed malaria, using geographic information systems and Getis-Ord Gi*(d) cluster analysis. Malaria incidence, transmission seasonality, and Plasmodium vivax:P. falciparum ratio remained almost unchanged from 2011 to 2013, but heterogeneity in distribution increased. The number of townships with confirmed malaria decreased significantly during the 3 years; incidence became increasingly concentrated within a few townships. High-/low-incidence clusters of P. falciparum shifted in location and size every year, whereas the locations of high-incidence P. vivax townships remained unchanged. All high-incidence clusters were located along the China–Myanmar border. Because of increasing heterogeneity in malaria distribution, microgeographic analysis of malaria transmission hot spots provided useful information for designing targeted malaria intervention during the elimination phase. PMID:27433877
Werner, R.; Stebel, K.; Hansen, H. G.; Hoppe, U.-P.; Gausa, M.; Kivi, R.; von der Gathen, P.; Orsolini, Y.; Kilifarska, N.
The geographic area at high latitudes beyond the polar circle is characterized with long darkness during the winter (polar night) and with a long summertime insolation (polar day). Consequentially, the polar vortex is formed and the surrounding strong polar jet is characterized by a strong potential vorticity gradient representing a horizontal transport barrier. The ozone dynamics of the lower and middle stratosphere is controlled both by chemical destruction processes and transport processes.To study the seasonal ozone variation at high latitudes, ozone vertical distributions are examined, collected from the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) (69.3°N, 16.0°E,) station at Andenes and from the stations at Sodankylä (67.4°N, 26.6°E) and at Ny-Ålesund (78.9°N, 11.9°E). The data sets cover the time period from 1994 until 2004. We find a second ozone maximum near 13-15 km, between the tropopause and the absolute ozone maximum near 17-20 km. The maximum is built up by the combination of air mass transport and chemical ozone destruction, mainly caused by the NOx catalytic cycle, which begins after the polar night and intensifies with the increasing day length. Formation of a troposphere inversion layer is observed. The inversion layer is thicker and reaches higher altitudes in winter rather than in summer. However, the temperature inversion during summer is stronger. The formation of an enhanced ozone number density is observed during the spring-summer period. The ozone is accumulated or becomes poor by synoptic weather patterns just above the tropopause from spring to summer. In seasonal average an ozone enhancement above the tropopause is obtained.The stronger temperature inversion during the summer period inhibits the vertical stratosphere-troposphere exchange. The horizontal advection in the upper troposphere and lower stratosphere is enforced during summer. The combination of these mechanisms generates a layer with a very low
Rocha, Bruno Coelho; Marques, Pedro Elias; Leoratti, Fabiana Maria de Souza; Junqueira, Caroline; Pereira, Dhelio Batista; Antonelli, Lis Ribeiro do Valle; Menezes, Gustavo Batista
SUMMARY Neutrophils are the most abundant leukocyte population in the bloodstream, the primary compartment of Plasmodium sp. infection. Yet, the role of these polymorphonuclear cells in mediating either resistance or pathogenesis of malaria is poorly understood. We report that circulating neutrophils from malaria patients are highly activated, as indicated by a strong type I interferon transcriptional signature, increased expression of surface activation markers, the enhanced release of reactive oxygen species and myeloperoxidase, as well as the high frequency of low-density granulocytes. The activation of neutrophils was associated with increased levels of serum alanine and aspartate aminotransferases, indicating liver damage. In a rodent malaria model, we observed an intense recruitment of neutrophils to liver sinusoids. Neutrophil migration, IL-1β and chemokine expression as well as liver damage were all dependent on type I interferon signaling. The data suggests that type I interferon signaling have a central role in neutrophil activation and malaria pathogenesis. PMID:26711347
Wilson, Laurence G.; Carter, Lucy M.; Reece, Sarah E.
Axonemes form the core of eukaryotic flagella and cilia, performing tasks ranging from transporting fluid in developing embryos to the propulsion of sperm. Despite their abundance across the eukaryotic domain, the mechanisms that regulate the beating action of axonemes remain unknown. The flagellar waveforms are 3D in general, but current understanding of how axoneme components interact stems from 2D data; comprehensive measurements of flagellar shape are beyond conventional microscopy. Moreover, current flagellar model systems (e.g., sea urchin, human sperm) contain accessory structures that impose mechanical constraints on movement, obscuring the “native” axoneme behavior. We address both problems by developing a high-speed holographic imaging scheme and applying it to the (male) microgametes of malaria (Plasmodium) parasites. These isolated flagella are a unique, mathematically tractable model system for the physics of microswimmers. We reveal the 3D flagellar waveforms of these microorganisms and map the differential shear between microtubules in their axonemes. Furthermore, we overturn claims that chirality in the structure of the axoneme governs the beat pattern [Hirokawa N, et al. (2009) Ann Rev Fluid Mech 41:53–72], because microgametes display a left- or right-handed character on alternate beats. This breaks the link between structural chirality in the axoneme and larger scale symmetry breaking (e.g., in developing embryos), leading us to conclude that accessory structures play a critical role in shaping the flagellar beat. PMID:24194551
Schultz, M G
There have been 4 waves of imported malaria in the USA. They occurred during the colonization of the country and during the Second World War, the UN Police Action in Korea, and the Viet-Nam conflict. The first 3 episodes are briefly described and the data on imported malaria from Viet-Nam are discussed in detail.Endemic malaria is resurgent in many tropical countries and international travel is also on the rise. This increases the likelihood of malaria being imported from an endemic area and introduced into a receptive area. The best defence for countries threatened by imported malaria is a vigorous surveillance programme. The principles of surveillance are discussed and an example of their application is provided by a description of the methods used to conduct surveillance of malaria in the USA.
Lindh, Markus V; Sjöstedt, Johanna; Andersson, Anders F; Baltar, Federico; Hugerth, Luisa W; Lundin, Daniel; Muthusamy, Saraladevi; Legrand, Catherine; Pinhassi, Jarone
Multiyear comparisons of bacterioplankton succession reveal that environmental conditions drive community shifts with repeatable patterns between years. However, corresponding insight into bacterioplankton dynamics at a temporal resolution relevant for detailed examination of variation and characteristics of specific populations within years is essentially lacking. During 1 year, we collected 46 samples in the Baltic Sea for assessing bacterial community composition by 16S rRNA gene pyrosequencing (nearly twice weekly during productive season). Beta-diversity analysis showed distinct clustering of samples, attributable to seemingly synchronous temporal transitions among populations (populations defined by 97% 16S rRNA gene sequence identity). A wide spectrum of bacterioplankton dynamics was evident, where divergent temporal patterns resulted both from pronounced differences in relative abundance and presence/absence of populations. Rates of change in relative abundance calculated for individual populations ranged from 0.23 to 1.79 day(-1) . Populations that were persistently dominant, transiently abundant or generally rare were found in several major bacterial groups, implying evolution has favoured a similar variety of life strategies within these groups. These findings suggest that high temporal resolution sampling allows constraining the timescales and frequencies at which distinct populations transition between being abundant or rare, thus potentially providing clues about physical, chemical or biological forcing on bacterioplankton community structure.
Machado, Patrícia; Manco, Licínio; Gomes, Cláudia; Mendes, Cristina; Fernandes, Natércia; Salomé, Graça; Sitoe, Luis; Chibute, Sérgio; Langa, José; Ribeiro, Letícia; Miranda, Juliana; Cano, Jorge; Pinto, João; Amorim, António; do Rosário, Virgílio E.; Arez, Ana Paula
Background Pyruvate kinase (PK) deficiency, causing hemolytic anemia, has been associated to malaria protection and its prevalence in sub-Saharan Africa is not known so far. This work shows the results of a study undertaken to determine PK deficiency occurrence in some sub-Saharan African countries, as well as finding a prevalent PK variant underlying this deficiency. Materials and Methods Blood samples of individuals from four malaria endemic countries (Mozambique, Angola, Equatorial Guinea and Sao Tome and Principe) were analyzed in order to determine PK deficiency occurrence and detect any possible high frequent PK variant mutation. The association between this mutation and malaria was ascertained through association studies involving sample groups from individuals showing different malaria infection and outcome status. Results The percentage of individuals showing a reduced PK activity in Maputo was 4.1% and the missense mutation G829A (Glu277Lys) in the PKLR gene (only identified in three individuals worldwide to date) was identified in a high frequency. Heterozygous carrier frequency was between 6.7% and 2.6%. A significant association was not detected between either PK reduced activity or allele 829A frequency and malaria infection and outcome, although the variant was more frequent among individuals with uncomplicated malaria. Conclusions This was the first study on the occurrence of PK deficiency in several areas of Africa. A common PKLR mutation G829A (Glu277Lys) was identified. A global geographical co-distribution between malaria and high frequency of PK deficiency seems to occur suggesting that malaria may be a selective force raising the frequency of this 277Lys variant. PMID:23082140
... critical role in development of those next-generation strategies. Read more about malaria prevention, treatment and control Global Cooperation Collaboration involving scientists from diverse disciplines is ...
Midekisa, A. A.; Wimberly, M. C.; Senay, G. B.
Tropical wetlands provide various beneficial ecosystem services; however, they can also facilitate the transmission of vector-borne diseases. Because wetlands serve as breeding habitats for Anopheles mosquitoes, particularly during the dry season, they are critical eco-hydrologic elements for malaria transmission. The overarching hypothesis of this study is that landscape and regional patterns of wetlands are associated with malaria risk in the Amhara region of Ethiopia. To test this hypothesis, we developed a random forest decision tree model to map seasonal and permanent wetlands in the Amhara region. Wetland training and validation data were acquired from high-resolution imagery in Google Earth and ground surveys. We evaluated the effectiveness of three random forest models using the following sets of predictor variables: (1) topographical indices from 30 m SRTM data, (2) individual reflectance bands and multispectral wetness indices from Landsat TM/ETM+ imagery, and (3) combined spectral and topographic data. The combined model produced the most accurate wetland maps, and we used it to map wetlands across the study area for 2000, 2005, and 2010. We found spatial associations between indicators of malaria risk from historical surveillance data and metrics of wetland cover at a district level. We also quantified seasonal moisture variability among three different land use land cover types (permanent wetland, seasonal wetland, and cropland) using Actual Evapotranspiration (ETa) over a ten year period (2001-2010) derived from MODIS imagery. We found that permanent and seasonal wetlands have peak moisture during the major malaria transmission season (September-November), whereas the permanent wetlands retain moisture and potentially sustain mosquito populations during the low transmission season (December-March). These findings about the spatial and temporal associations of malaria risk and wetlands can help to highlight areas that likely sustain transmission during
Barnes, Karen I; Chanda, Pascalina; Ab Barnabas, Gebre
of malaria-specific mortality by 37%. Additionally, the malaria parasite reservoir was three-fold lower in the intervention district than in the control district during the 2005 high-transmission season. Artemisinin-based combination therapy has made a substantial contribution to reducing the burden of malaria in sub-Saharan Africa. PMID:19818175
Lowe, R.; Chirombo, J.; Tompkins, A. M.
the unobserved confounding factors that influence malaria, which are not accounted for using measured covariates, a negative binomial generalised linear mixed model (GLMM) is adopted, which includes structured and unstructured spatial and temporal random effects. The parameters in this spatio-temporal Bayesian hierarchical model are estimated using Markov Chain Monte Carlo (MCMC). This allows posterior predictive distributions for disease risk to be derived for each spatial location and time period. A novel visualisation technique is then used to display seasonal probabilistic forecasts of malaria risk, derived from the developed model using pre-defined risk category thresholds, on a map. This technique allows decision makers to identify areas where the model predicts with certainty a particular malaria risk category (high, medium or low); in order to effectively target limited resources to those districts most at risk for a given season.
Bartoloni, Alessandro; Zammarchi, Lorenzo
The first symptoms of malaria, common to all the different malaria species, are nonspecific and mimic a flu-like syndrome. Although fever represents the cardinal feature, clinical findings in malaria are extremely diverse and may range in severity from mild headache to serious complications leading to death, particularly in falciparum malaria. As the progression to these complications can be rapid, any malaria patient must be assessed and treated rapidly, and frequent observations are needed to look for early signs of systemic complications. In fact, severe malaria is a life threatening but treatable disease. The protean and nonspecific clinical findings occurring in malaria (fever, malaise, headache, myalgias, jaundice and sometimes gastrointestinal symptoms of nausea, vomiting and diarrhoea) may lead physicians who see malaria infrequently to a wrong diagnosis, such as influenza (particularly during the seasonal epidemic flu), dengue, gastroenteritis, typhoid fever, viral hepatitis, encephalitis. Physicians should be aware that malaria is not a clinical diagnosis but must be diagnosed, or excluded, by performing microscopic examination of blood films. Prompt diagnosis and appropriate treatment are then crucial to prevent morbidity and fatal outcomes. Although Plasmodium falciparum malaria is the major cause of severe malaria and death, increasing evidence has recently emerged that Plasmodium vivax and Plasmodium knowlesi can also be severe and even fatal. PMID:22708041
Tawiah, Theresa; Hansen, Kristian Schultz; Baiden, Frank; Bruce, Jane; Tivura, Mathilda; Delimini, Rupert; Amengo-Etego, Seeba; Chandramohan, Daniel; Owusu-Agyei, Seth; Webster, Jayne
Background The presumptive approach of confirming malaria in health facilities leads to over-diagnosis of malaria, over use of anti-malaria drugs and the risk of drug resistance development. WHO recommends parasitological confirmation before treatment with artemisinin-based combination therapy (ACT) in all suspected malaria patients. The use of malaria rapid diagnostic tests (mRDTs) would make it possible for prescribers to diagnose malaria at point-of-care and better target the use of antimalarials. Therefore, a cost-effectiveness analysis was performed on the introduction of mRDTs for management of malaria in under-five children in a high transmission area in Ghana where presumptive diagnosis was the norm in public health centres. Methods A cluster-randomised controlled trial where thirty-two health centres were randomised into test-based diagnosis of malaria using mRDTs (intervention) or clinical judgement (control) was used to measure the effect of mRDTs on appropriate treatment: ‘a child with a positive reference diagnosis prescribed a course of ACT or a child with a negative reference diagnosis not given an ACT’. Cost data was collected from five purposively selected health centres and used to estimate the health sector costs of performing an mRDT and treat children for malaria and other common febrile illnesses. Costs of training healthcare personnel and supervision in the study period were also collected. A sample of caregivers to children participating in the trial was interviewed about household cost incurred on transport, drugs, fees, and special food during a period of one week after the health centre visit as well as days unable to work. A decision model approach was used to calculate the incremental cost-effectiveness ratios (ICERs). Univariate and multivariate sensitivity analyses were applied to assess the robustness of ICERs. Results The availability of mRDTs for malaria diagnosis resulted in fewer ACT treatments compared to the clinical
Pinchoff, Jessie; Chaponda, Mike; Shields, Timothy; Lupiya, James; Kobayashi, Tamaki; Mulenga, Modest; Moss, William J.; Curriero, Frank C.
Malaria risk maps may be used to guide policy decisions on whether vector control interventions should be targeted and, if so, where. Active surveillance for malaria was conducted through household surveys in Nchelenge District, Zambia from April 2012 through December 2014. Households were enumerated based on satellite imagery and randomly selected for study enrollment. At each visit, participants were administered a questionnaire and a malaria rapid diagnostic test (RDT). Logistic regression models were used to construct spatial prediction risk maps and maps of risk uncertainty. A total of 461 households were visited, comprising 1,725 participants, of whom 48% were RDT positive. Several environmental features were associated with increased household malaria risk in a multivariable logistic regression model adjusting for seasonal variation. The model was validated using both internal and external evaluation measures to generate and assess root mean square error, as well as sensitivity and specificity for predicted risk. The final, validated model was used to predict and map malaria risk including a measure of risk uncertainty. Malaria risk in a high, perennial transmission setting is widespread but heterogeneous at a local scale, with seasonal variation. Targeting malaria control interventions may not be appropriate in this epidemiological setting. PMID:26416106
Waitumbi, John N; Kuypers, Jane; Anyona, Samuel B; Koros, Joseph N; Polhemus, Mark E; Gerlach, Jay; Steele, Matthew; Englund, Janet A; Neuzil, Kathleen M; Domingo, Gonzalo J
A cross-sectional study was performed in children 5 through 10 years of age presenting to outpatient clinics in Nyanza Province, Kenya, in which nasal swab and blood specimens were collected during the high malaria transmission season. Patients presenting with malaria-like symptoms within 4 days of fever onset were enrolled in the study. Plasmodium parasitemia was determined by blood smear microscopy. Nasal swabs were screened for a panel of respiratory viruses by polymerase chain reaction. Influenza A, rhinoviruses, and other respiratory viruses were detected in 18%, 26%, and 12% of 197 specimens, respectively. Four of 36 patients with influenza A had a positive malaria blood slide, compared with 20 of 52 patients with rhinovirus. A significant burden of disease caused by influenza A in febrile children during the study period was observed, highlighting the need for further research into the burden of influenza disease in regions where malaria is holoendemic.
Breman, Joel G
The renewed interest in malaria research and control is based on the intolerable toll this disease takes on young children and pregnant women in Africa and other vulnerable populations; 150 to 300 children die each hour from malaria amounting to 1 to 2 million deaths yearly. Malaria-induced neurologic impairment, anemia, hypoglycemia, and low birth weight imperil normal development and survival. Resistance of Plasmodium falciparum to drugs and Anopheles mosquitoes to insecticides has stimulated discovery and development of artemisinin-based combination treatments (ACTs) and other drugs, long-lasting insecticide-treated bednets (with synthetic pyrethroids) and a search for non-toxic, long-lasting, affordable insecticides for indoor residual spraying (IRS). Malaria vaccine development and testing are progressing rapidly and a recombinant protein (RTS,S/AS02A) directed against the circumsporozoite protein is soon to be in Phase 3 trials. Support for malaria control, research, and advocacy through the Global Fund for HIV/AIDS, Tuberculosis and Malaria, the U.S. President's Malaria Initiative, the Bill & Melinda Gates Foundation, WHO and other organizations is resulting in decreasing morbidity and mortality in many malarious countries. Sustainability of effective programs through training and institution strengthening will be the key to malaria elimination coupled with improved surveillance and targeted research.
Sinyange, Nyambe; Kumar, Ramya; Inambao, Akatama; Moonde, Loveness; Chama, Jonathan; Banda, Mapopa; Tembo, Elliot; Nsonga, Beron; Mwaba, John; Fwoloshi, Sombo; Musokotwane, Kebby; Chizema, Elizabeth; Kapin'a, Muzala; Hang'ombe, Benard Mudenda; Baggett, Henry C; Hachaambwa, Lottie
Outbreaks of plague have been recognized in Zambia since 1917 (1). On April 10, 2015, Zambia's Ministry of Health was notified by the Eastern Provincial Medical Office of possible bubonic plague cases in Nyimba District. Eleven patients with acute fever and cervical lymphadenopathy had been evaluated at two rural health centers during March 28-April 9, 2015; three patients died. To confirm the outbreak and develop control measures, the Zambia Ministry of Health's Field Epidemiology Training Program (ZFETP) conducted epidemiologic and laboratory investigations in partnership with the University of Zambia's schools of Medicine and Veterinary Medicine and the provincial and district medical offices. Twenty-one patients with clinically compatible plague were identified, with symptom onset during March 26-May 5, 2015. The median age was 8 years, and all patients were from the same village. Blood specimens or lymph node aspirates from six (29%) patients tested positive for Yersinia pestis by polymerase chain reaction (PCR). There is an urgent need to improve early identification and treatment of plague cases. PCR is a potential complementary tool for identifying plague, especially in areas with limited microbiologic capacity. Twelve (57%) patients, including all six with PCR-positive plague and all three who died, also tested positive for malaria by rapid diagnostic test (RDT). Plague patients coinfected with malaria might be misdiagnosed as solely having malaria, and appropriate antibacterial treatment to combat plague might not be given, increasing risk for mortality. Because patients with malaria might be coinfected with other pathogens, broad spectrum antibiotic treatment to cover other pathogens is recommended for all children with severe malaria, until a bacterial infection is excluded.
Lin, Jing-wen; Sodenkamp, Jan; Cunningham, Deirdre; Deroost, Katrien; Tshitenge, Tshibuayi Christine; McLaughlin, Sarah; Lamb, Tracey J.; Spencer-Dene, Bradley; Hosking, Caroline; Ramesar, Jai; Janse, Chris J.; Graham, Christine; O’Garra, Anne; Langhorne, Jean
The influence of parasite genetic factors on immune responses and development of severe pathology of malaria is largely unknown. In this study, we performed genome-wide transcriptomic profiling of mouse whole blood during blood-stage infections of two strains of the rodent malaria parasite Plasmodium chabaudi that differ in virulence. We identified several transcriptomic signatures associated with the virulent infection, including signatures for platelet aggregation, stronger and prolonged anemia and lung inflammation. The first two signatures were detected prior to pathology. The anemia signature indicated deregulation of host erythropoiesis, and the lung inflammation signature was linked to increased neutrophil infiltration, more cell death and greater parasite sequestration in the lungs. This comparative whole-blood transcriptomics profiling of virulent and avirulent malaria shows the validity of this approach to inform severity of the infection and provide insight into pathogenic mechanisms. PMID:28155887
Ghanchi, N K; Shakoor, S; Thaver, A M; Khan, M S; Janjua, A; Beg, M A
Malaria transmission is unstable in Pakistan with the highest number of cases reported during the monsoon season. Despite its high incidence, malaria is still a poorly resourced, poorly funded and an uncontrolled disease especially in far-flung areas. Pakistan's National Malaria Control Program (NMCP), although operational since its inception in 1947, has suffered due to the unstable political, socioeconomic and financial situation prevalent in the country. In Pakistan, more than 300 000 cases of malaria are reported every year with 68% of the cases caused by Plasmodium vivax. It is estimated that about 70-80% of the population accesses the private sector for treatment. As the private sector does not routinely report data to the government, the actual malaria burden could be 4-5 times higher than reported. P. vivax now accounts for more than 85% of all cases requiring hospital admission compared to 54% in 2000. In this review, we have described the saga of poor control of malaria in Pakistan over several years in context of restructuring of the Malaria Control Program, challenges to improvement, and way forward.
MEMON, Muhammad Sadik; SOLANGI, Shamsuddin; LAKHO, Shabana; ARAIN, Zain Islam; NAZ, Farukh; ZAKI, Madiha
Abstract Background Malaria is the second most frequent clinically suspected disease entity after acute respiratory tract infection in developing countries. Active malarial transmission occurs throughout the year, while aggressive out bursts of disease are seen mainly during and after the ‘monsoon’ season. This study aimed to determine the morbidity and mortality associated with malaria during flood at Isra University Hospital, Hyderabad. Methods This prospective observational study was done at Isra University Hospital Hyderabad during monsoon flooding from July 2011 to October 2011. All 883 patients presented with symptoms of malaria (fever, headache, and vomiting) were evaluated and diagnostic tool ICT-MP was used for the detection of malaria parasite among them. Results Seventy four (8.38%) patients diagnosed for malaria. The mean age and SD was 30.11 ± 1.67 years. Overall mortality due to malaria observed (18.9%). Mortality rate significantly observed high in pregnant women (0.005) and in those patients who developed complications such as, pneumonia (P = 0.04), renal failure (P = 0.04), Unconsciousness (P = 0.001), and Septicemia (P = 0.001). Conclusion A Significant increase in the morbidity and mortality in patients with malaria after flood noticed. The probability of getting poor outcome is also associated when patient develop complications. PMID:26060676
Lalloo, David G; Shingadia, Delane; Pasvol, Geoffrey; Chiodini, Peter L; Whitty, Christopher J; Beeching, Nicholas J; Hill, David R; Warrell, David A; Bannister, Barbara A
Malaria is the tropical disease most commonly imported into the UK, with 1500-2000 cases reported each year, and 10-20 deaths. 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. Most non-falciparum malaria cases are caused by Plasmodium vivax; a few cases are caused by the other two species of Plasmodium: Plasmodium ovale or Plasmodium malariae. Mixed infections with more than 1 species of parasite can occur; they commonly involve P. falciparum with the attendant risks of severe malaria. Management of malaria depends on awareness of the diagnosis and on performing the correct diagnostic tests: the diagnosis cannot be excluded until 3 blood specimens have been examined by an experienced microscopist. There are no typical clinical features of malaria, even fever is not invariably present. The optimum diagnostic procedure is examination of thick and thin blood films by an expert to detect and speciate the malarial parasites; P. falciparum malaria can be diagnosed almost as accurately using rapid diagnostic tests (RDTs) which detect plasmodial antigens or enzymes, although RDTs for other Plasmodium species are not as reliable. The treatment of choice for non-falciparum malaria is a 3-day course of oral chloroquine, to which only a limited proportion of P. vivax strains have gained resistance. 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. This must 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. Uncomplicated P. falciparum malaria can be treated orally with quinine, atovaquone plus proguanil (Malarone) or co-artemether (Riamet
Milner, Danny; Factor, Rachel; Whitten, Rich; Carr, Richard A; Kamiza, Steve; Pinkus, Geraldine; Molyneux, Malcolm; Taylor, Terrie
Respiratory signs are common in African children where malaria is highly endemic, and thus, parsing the role of pulmonary pathology in illness is challenging. We examined the lungs of 100 children from an autopsy series in Blantyre, Malawi, many of whom death was attributed to Plasmodium falciparum malaria. Our aim was to describe the pathologic manifestations of fatal malaria; to understand the role of parasites, pigment, and macrophages; and to catalog comorbidities. From available patients, which included 55 patients with cerebral malaria and 45 controls, we obtained 4 cores of lung tissue for immunohistochemistry and morphological evaluation. We found that, in patients with cerebral malaria, large numbers of malaria parasites were present in pulmonary alveolar capillaries, together with extensive deposits of malaria pigment (hemozoin). The number of pulmonary macrophages in this vascular bed did not differ between patients with cerebral malaria, noncerebral malaria, and nonmalarial diagnoses. Comorbidities found in some cerebral malaria patients included pneumonia, pulmonary edema, hemorrhage, and systemic activation of coagulation. We conclude that the respiratory distress seen in patients with cerebral malaria does not appear to be anatomic in origin but that increasing malaria pigment is strongly associated with cerebral malaria at autopsy.
Deressa, Wakgari; Ali, Ahmed; Hailemariam, Damen
A range of activities are currently underway to improve access to malaria prevention and control interventions. As disease control strategies change over time, it is crucial to understand the health-seeking behaviour and the local socio-cultural context in which the changes in interventions operate. This paper reflects on how people in an area of seasonal malaria perceive the causes and transmission of the disease, and what prevention and treatment measures they practise to cope with the disease. It also highlights some of the challenges of malaria treatment for health care providers. The study was undertaken in 2003 in Adami Tulu District in south-central Ethiopia, where malaria is a major health problem. Pre-tested structured questionnaires and focus group discussions were conducted among men and women. Malaria, locally known as busa, was perceived as the most important cause of ill health in the area. Respondent's perception and knowledge about the cause and transmission of the disease were relatively high. The newly introduced insecticide-treated nets were not popular in the area, and only 6.4% of households possessed at least one. The results showed that patients use multiple sources of health care for malaria treatment. Public health facilities, private clinics and community health workers were the main providers of malaria treatment. Despite higher treatment costs, people preferred to use private health care providers for malaria treatment due to the higher perceived quality of care they offer. In conclusion, effort in the prevention and control of malaria should be intensified through addressing not only public facilities, but also the private sector and community-based control interventions. Appropriate and relevant information on malaria should be disseminated to the local community. The authors propose the provision of effective antimalarial drugs and malaria prevention tools such as subsidized or free insecticide-treated nets.
Gantz, Valentino M; Jasinskiene, Nijole; Tatarenkova, Olga; Fazekas, Aniko; Macias, Vanessa M; Bier, Ethan; James, Anthony A
Genetic engineering technologies can be used both to create transgenic mosquitoes carrying antipathogen effector genes targeting human malaria parasites and to generate gene-drive systems capable of introgressing the genes throughout wild vector populations. We developed a highly effective autonomous Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-associated protein 9 (Cas9)-mediated gene-drive system in the Asian malaria vector Anopheles stephensi, adapted from the mutagenic chain reaction (MCR). This specific system results in progeny of males and females derived from transgenic males exhibiting a high frequency of germ-line gene conversion consistent with homology-directed repair (HDR). This system copies an ∼ 17-kb construct from its site of insertion to its homologous chromosome in a faithful, site-specific manner. Dual anti-Plasmodium falciparum effector genes, a marker gene, and the autonomous gene-drive components are introgressed into ∼ 99.5% of the progeny following outcrosses of transgenic lines to wild-type mosquitoes. The effector genes remain transcriptionally inducible upon blood feeding. In contrast to the efficient conversion in individuals expressing Cas9 only in the germ line, males and females derived from transgenic females, which are expected to have drive component molecules in the egg, produce progeny with a high frequency of mutations in the targeted genome sequence, resulting in near-Mendelian inheritance ratios of the transgene. Such mutant alleles result presumably from nonhomologous end-joining (NHEJ) events before the segregation of somatic and germ-line lineages early in development. These data support the design of this system to be active strictly within the germ line. Strains based on this technology could sustain control and elimination as part of the malaria eradication agenda.
Bismil'din, F B; Shapieva, Zh Zh; Anpilova, E N
. messeae, is found throughout the country: in a few areas An. hyrcanus and An. claviger are found and, in the south, An. pulcherrimus. Data from recent years show the presence of An. superpictus, An. plumbeus and An. algeriensis. In 1999, from data collected during systematic observations of the phenology and seasonal variations in the number of Anopheles at 114 observation posts, the average seasonal numerical indicators for the mosquito imago reached a maximum of between 21 and 46.5 adult mosquitoes per cattle shed, up to 2.7-3.3 adult mosquitoes per residential building and 30-67.3 larvae per square metre of surface water. According to the results of large scale trapping programmes (486 communities were screened in 1999), the maximum value of the numerical indicator was 16.8-74.1 adult mosquitoes per cattle shed and 4.1-3.8 adult mosquitoes per residential building. In 1999, compared with 1998, the number of malarial mosquitoes detected throughout the country declined encouragingly, or stayed at the same level, which is one of the factors responsible for the country's favourable epidemiological situation with regard to malaria. According to data going back many years, there has been a significant increase in the number of mosquitoes at some observation posts in Almaty, East Kazakhstan and Kyzlorda oblasts. There is a tendency everywhere for the numbers of imagos detected in residential buildings to increase, which presents a definite epidemiological risk that indigenous malaria will re-emerge if the disease is imported into Kazakhstan from countries which suffer from it. If we consider the species of mosquito present in the country and the temperature factor (the number of days in the year when the average daily temperature is over 16 degrees C), the country can be divided, on the basis of incomplete 1999 data, into zones at very high risk of re-emergence of malaria (Almaty, Zhambyl and South Kazakhstan oblasts), high risk (Karaganda oblasts and Almaty city), medium
... Malaria Branch clinician. firstname.lastname@example.org Malaria Treatment (United States) Recommend on Facebook Tweet Share Compartir Treatment of Malaria: Guidelines For Clinicians (United States) Download PDF version of Parts 1-3 formatted ...
Maggioni, V.; Mousam, A.; Delamater, P. L.; Cash, B. A.; Quispe, A.
Malaria is a public health threat to people globally leading to 198 million cases and 584,000 deaths annually. Outbreaks of vector borne diseases such as malaria can be significantly impacted by climate variables such as precipitation. For example, an increase in rainfall has the potential to create pools of water that can serve as breeding locations for mosquitos. Peru is a country that is currently controlling malaria, but has not been able to completely eliminate the disease. Despite the various initiatives in order to control malaria - including regional efforts to improve surveillance, early detection, prompt treatment, and vector management - malaria cases in Peru have risen between 2011 and 2014. The purpose of this study is to test the hypothesis that climate variability plays a fundamental role in malaria occurrence over a 12-year period (2003-2014) in Peru. When analyzing climate variability, it is important to obtain high-quality, high-resolution data for a time series long enough to draw conclusion about how climate variables have been and are changing. Remote sensing is a powerful tool for measuring and monitoring climate variables continuously in time and space. A widely used satellite-based precipitation product, the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA), available globally since 1998, was used to obtain 3-hourly data with a spatial resolution of 0.25° x 0.25°. The precipitation data was linked to weekly (2003-2014) malaria cases collected by health centers and available at a district level all over Peru to investigate the relationship between precipitation and the seasonal and annual variations in malaria incidence. Further studies will incorporate additional climate variables such as temperature, humidity, soil moisture, and surface pressure from remote sensing data products and climate models. Ultimately, this research will help us to understand if climate variability impacts malaria incidence
Rabarijaona, Léon Paul; Ariey, Frédéric; Matra, Robert; Cot, Sylvie; Raharimalala, Andrianavalona Lucie; Ranaivo, Louise Henriette; Le Bras, Jacques; Robert, Vincent; Randrianarivelojosia, Milijaona
Background The study of urban malaria is an area undergoing rapid expansion, after many years of neglect. The problem of over-diagnosis of malaria, especially in low transmission settings including urban areas, is also receiving deserved attention. The primary objective of the present study was to assess the frequency of malaria among febrile outpatients seen in private and public primary care facilities of Antananarivo. The second aim was to determine, among the diagnosed malaria cases, the contribution of autochthonous urban malaria. Methods Two cross-sectional surveys in 43 health centres in Antananarivo in February 2003 (rainy season) and in July 2003 (dry season) were conducted. Consenting clinically suspected malaria patients with fever or history of fever in the past 48 hours were included. Malaria rapid diagnostic tests and microscopy were used to diagnose malaria. Basic information was collected from patients to try to identify the origin of the infection: autochthonous or introduced. Results In February, among 771 patients, 15 (1.9%) positive cases were detected. Three malaria parasites were implicated: Plasmodium. falciparum (n = 12), Plasmodium vivax (n = 2) and Plasmodium. ovale (n = 1). Only two cases, both P. falciparum, were likely to have been autochthonous (0.26%). In July, among 739 blood smears examined, 11 (1.5%) were positive: P. falciparum (n = 9) and P. vivax (n = 2). Three cases of P. falciparum malaria were considered to be of local origin (0.4%). Conclusion This study demonstrates that malaria cases among febrile episodes are low in Antananarivo and autochthonous malaria cases exist but are rare. PMID:16573843
Miller, Louis H.; Good, Michael F.; Milon, Genevieve
Malaria is a disease caused by repeated cycles of growth of the parasite Plasmodium in the erythrocyte. Various cellular and molecular strategies allow the parasite to evade the human immune response for many cycles of parasite multiplication. Under certain circumstances Plasmodium infection causes severe anemia or cerebral malaria; the expression of disease is influenced by both parasite and host factors, as exemplified by the exacerbation of disease during pregnancy. This article provides an overview of malaria pathogenesis, synthesizing the recent field, laboratory, and epidemiological data that will lead to the development of strategies to reduce mortality and morbidity.
White, N J
Increasing drug resistance in Plasmodium falciparum and a resurgence of malaria in tropical areas have effected a change in treatment of malaria in the last two decades. Symptoms of malaria are fever, chills, headache, and malaise. The prognosis worsens as the parasite counts, counts of mature parasites, and counts of neutrophils containing pigment increase. Treatment depends on severity, age of patient, degree of background immunity, likely pattern of susceptibility to antimalarial drugs, and the cost and availability of drugs. Chloroquine should be used for P. vivax, P. malariae, and P. ovale. P. vivax has shown high resistance to chloroquine in Oceania, however. Primaquine may be needed to treat P. vivax and P. ovale to rid the body of hypnozoites that survive in the liver. Chloroquine can treat P. falciparum infections acquired in North Africa, Central America north of the Panama Canal, Haiti, or the Middle East but not in most of Africa and some parts of Asia and South America. In areas of low grade resistance to chloroquine, amodiaquine can be used to effectively treat falciparum malaria. A combination of sulfadoxine-pyrimethamine is responsive to falciparum infections with high grade resistance to chloroquine. Mefloquine, halofantrine, or quinine with tetracycline can be used to treat multidrug-resistant P. falciparum. Derivatives of artemisinin obtained from qinghao or sweet wormwood developed as pharmaceuticals in China are the most rapidly acting of all antimalarial drugs. Children tend to tolerate antimalarial drugs well. Children who weigh less than 15 kg should not be given mefloquine. Health workers should not prescribe primaquine to pregnant women or newborns due to the risk of hemolysis. Chloroquine, sulfadoxine-pyrimethamine, quinine, and quinidine can be safely given in therapeutic doses throughout pregnancy. Clinical manifestations of severe malaria are hypoglycemia, convulsions, severe anemia, acute renal failure, jaundice, pulmonary edema
Carme, B; Venturin, C
In 1996, malaria involving Plasmodium vivax, Plasmodium falciparum, and, to a lesser extent, Plasmodium malariae was endemic in 21 countries in the Americas. The Amazon river basin and bordering areas including the Guyanas were the most affected zones. Until the mid 1970s, endemic malaria appeared to be under control. However in the ensuing 15 year period, the situation deteriorated drastically. Although trends varied depending on location, aggregate indexes indicated a twofold increase with recrudescence in previously settled areas and emergence in newly populated zones. Since 1990, the situation has worsened further in some areas where increased incidences have been associated with a high levels of drug-resistant Plasmodium falciparum. However this species remains in minority except in the Guyanas where the highest annual incidences (100 to 500 cases per 1000) and the most drug-resistant Plasmodium have been reported. The causes underlying this deterioration are numerous and complex. In regions naturally prone to transmission of the disease, outbreaks have been intensified by unrestrained settlement. The resulting deforestation has created new breeding areas for Anopheles darlingi, the main vector of malaria in the Americas. Migration of poor populations to newly opened farming and mining areas has created highly exposed areas for malaria infection. Implementation of adequate medical care and prevention measures has been hindered by a lack of money and sociopolitical unrest. Climatic phenomenon related the El Nino have also been favorable to the return of malaria to the region. Except with regard to financial resources and political unrest, the same risk factors for malaria are present in French Guiana.
Ciminera, Paul; Brundage, John
U.S. service members are often deployed to regions endemic for malaria. Preventive measures play an important role in mitigating the risk of disease and adverse effects on mission performance. Currently, a large contingent of U.S. forces is deployed in malarious regions in southeast and southwest Asia. The purpose of this study was to describe malaria cases reported by the tri-service reportable medical events system in terms of exposure (deployment history) and latency of infection. We conducted a retrospective analysis of population health data routinely collected for disease surveillance. All malaria reports received into the Defense Medical Surveillance System by January 3, 2006 with a date of onset between January 1, 2000 and December 31, 2005 in which the individual diagnosed is a member of the active or reserve military components linked to personnel and deployment data were analyzed to determine assignment and deployment history. The main outcome measure was the ICD9-CM diagnosis of malaria (Plasmodium vivax, P. falciparum, P. ovale, P. malaria, and unspecified malaria) by date of onset and days from exposure. A total of 423 cases of malaria were reported during the study period. The Army (n = 325) and the Marine Corps (n = 46) had the highest number of reported cases. Plasmodium vivax (n = 242) and P. falciparum (n = 92) caused nearly four-fifths of all reported cases. During the period from 2003 through 2005, 34% of deployed cases were exposed to more than one malaria-endemic region. Seventy-four cases had been assigned in the Republic of Korea, and all were present in Korea during the high risk transmission period. Seventy-eight cases had documented service in Afghanistan; only 4 had off-season exposure and no other documented exposures. Sixty cases had documented exposure during Operation Iraqi Freedom (OIF). Only six seasonally exposed and six off seasonally exposed OIF cases had no other documented exposure. Fifty percent of Korean cases were
Kormilenko, I V; Aĭdinov, G T; Shvager, M M
In the Rostov Region, no cases of local malaria transmission have been notified since 1958, but cases of import malaria are recorded every year. The region is one of malaria-susceptible areas in the Russian Federation, which is characterized by intensive migration, the malariogenic potential sufficient for local transmission (malariogenic index 1.2), and the optimum conditions for resurgence of malaria when it is imported. The prevention of undesirable consequences of malaria importation requires the strict monitoring of feverish patients, cohorts of high-risk patients who go for trips to malaria-endemic countries.
Kim, Kwang-Yul; Roh, Joon-Woo; Lee, Dong-Kyou; Jhun, Jong-Ghap
Three distinct physical mechanisms in the seasonal cycle of the 120 day (19 May to 15 September) summer precipitation in Korea (126°E-130°E, 33°N-38°N) were identified using the 1979-2008 observed precipitation records at 61 Korea Meteorological Administration stations. Detailed space-time structures of the physical mechanisms of precipitation variability were derived using the daily National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis data over Asia (80°E-180°E, 0°-60°N). The seasonal cycle of summertime precipitation in Korea exhibits three principal temporal scales (seasonal, subseasonal, and high-frequency components) of variability, each with distinct physical mechanisms. The seasonal component represents the variability associated with the evolution of the Asian summer monsoon, specifically the East Asia summer monsoon, governed primarily by large-scale circulation as a result of changes in sea level pressure contrasts between the Asian continent and the surrounding oceans. The arrival and the duration of a monsoon front primarily shape the seasonal evolution of precipitation in Korea. The bimodal peaks are due to the low-level circulation change as a result of redistribution of temperature and, subsequently, of sea level pressure during summer. The subseasonal component has characteristic time scales of 10-30 days and is associated with eastward-moving upper-level disturbances at ˜40°N. The upper-level disturbances affect the meridional circulations, resulting in low-level convergence/divergence not only underneath but also to the south and to the north of the disturbance. From mid-July to mid-August, the subseasonal component is more clearly observable, and the period of oscillations is generally shorter, than during early or late summer. The high-frequency component with time scales of less than 10 days is associated with midlatitude baroclinic Rossby waves; synoptic-scale variations of upper
Voepel, Nadja; Boes, Alexander; Edgue, Güven; Beiss, Veronique; Kapelski, Stephanie; Reimann, Andreas; Schillberg, Stefan; Pradel, Gabriele; Fendel, Rolf; Scheuermayer, Matthias; Spiegel, Holger; Fischer, Rainer
Plants have emerged as low-cost production platforms suitable for vaccines targeting poverty-related diseases. Besides functional efficacy, the stability, yield, and purification process determine the production costs of a vaccine and thereby the feasibility of plant-based production. We describe high-level plant production and functional characterization of a malaria vaccine candidate targeting the pre-erythrocytic stage of Plasmodium falciparum. CCT, a fusion protein composed of three sporozoite antigens (P. falciparum cell traversal protein for ookinetes and sporozoites [PfCelTOS], P. falciparum circumsporozoite protein [PfCSP], and P. falciparum thrombospondin-related adhesive protein [PfTRAP]), was transiently expressed by agroinfiltration in Nicotiana benthamiana leaves, accumulated to levels up to 2 mg/g fresh leaf weight (FLW), was thermostable up to 80°C and could be purified to >95% using a simple two-step procedure. Reactivity of sera from malaria semi-immune donors indicated the immunogenic conformation of the purified fusion protein consisting of PfCelTOS, PfCSP_TSR, PfTRAP_TSR domains (CCT) protein. Total IgG from the CCT-specific mouse immune sera specifically recognized P. falciparum sporozoites in immunofluorescence assays and induced up to 35% inhibition in hepatocyte invasion assays. Featuring domains from three promising sporozoite antigens with different roles (attachment and cell traversal) in the hepatocyte invasion process, CCT has the potential to elicit broader immune responses against the pre-erythrocytic stage of P. falciparum and represents an interesting new candidate, also as a component of multi-stage, multi-subunit malaria vaccine cocktails.
Lwin, Khin Maung; Phyo, Aung Pyae; Tarning, Joel; Hanpithakpong, Warunee; Ashley, Elizabeth A.; Lee, Sue J.; Cheah, Phaikyeong; Singhasivanon, Pratap; White, Nicholas J.; Lindegårdh, Niklas
Intermittent preventive treatment (IPT) is increasingly used to reduce malaria morbidity and mortality in children and pregnant women. The efficacy of IPT depends on the pharmacokinetic and pharmacodynamic properties of the antimalarial drugs used. Healthy adult male volunteers whose occupation put them at high risk of malaria on the Northwest border of Thailand were randomized to receive a 3-day-treatment dose of dihydroartemisinin-piperaquine monthly (DPm) or every 2 months (DPalt) or an identical placebo with or without fat (6.4g/dose) over a 9-month period. All volunteers were monitored weekly. One thousand adults were recruited. Dihydroartemisinin-piperaquine was well tolerated. There were 114 episodes of malaria (49 Plasmodium falciparum, 63 P. vivax, and 2 P. ovale). The protective efficacy against all malaria at 36 weeks was 98% (95% confidence interval [CI], 96% to 99%) in the DPm group and 86% (95% CI, 81% to 90%) in the DPalt group (for both, P < 0.0001 compared to the placebo group). As a result, the placebo group also had lower hematocrits during the study (P < 0.0001). Trough plasma piperaquine concentrations were the main determinant of efficacy; no malaria occurred in participants with a trough concentration above 31 ng/ml. Neither plasma piperaquine concentration nor efficacy was influenced by the coadministration of fat. DPm is safe to use and is effective in the prevention of malaria in adult males living in an area where P. vivax and multidrug-resistant P. falciparum malaria are endemic. PMID:22252804
Kreuels, Benno; Ehrhardt, Stephan; Kreuzberg, Christina; Adjei, Samuel; Kobbe, Robin; Burchard, Gerd D; Ehmen, Christa; Ayim, Matilda; Adjei, Ohene; May, Jürgen
Background While the protective effects of sickle cell trait (HbAS) against severe malaria and the resulting survival advantage are well known, the impact on the physical development in young children remains unclear. This study was aimed to investigate the relationship between HbS carriage and stunting in children below two years of age in a cohort from the Ashanti Region, Ghana. Methods 1,070 children were recruited at three months of age and followed-up for 21 months with anthropometric measurements performed every three months. Incidence rate ratios with 95% confidence intervals were calculated by Poisson regression to estimate the association of β-globin genotypes with the number of malaria episodes. Odds ratios (OR) were calculated for the association between the occurrence of β-globin genotypes and/or malaria episodes and stunting. The age-dependent between-group and within-group effects for the β-globin genotypes were assessed by population-averaged models estimated by generalized estimation equation with autoregressive correlation structure. Results Analyses showed a significantly lower age-dependent risk of stunting (OR 0.56; 95% CI 0.33–0.96) in carriers of the HbAS genotype (n = 102) in comparison to those with HbAA (n = 692). This effect was restricted to children who experienced malaria episodes during the observation period suggesting that the beneficial effect of the β-globin HbS variant on the incidence of stunting is closely linked to its protection from mild malaria episodes. Conclusion The lower risk of chronic malnutrition in early childhood, mediated by protection against mild malaria episodes, may contribute to the survival advantage of HbAS carriers in areas of high malaria transmission. PMID:19149873
Some have argued that the vaccine against malaria developed by Manuel Pattaroyo, a Colombian scientist, is being tested prematurely in humans and that it is unlikely to be successful. While the Pattaroyo vaccine has been shown to confer protection against the relatively mild malaria found in Colombia, doubts exist over whether it will be effective in Africa. Encouraging first results, however, are emerging from field tests in Tanzania. The vaccine triggered a strong new immune response, even in individuals previously exposed to malaria. Additional steps must be taken to establish its impact upon mortality and morbidity. Five major trials are underway around the world. The creator estimates that the first ever effective malaria vaccine could be available for widespread use within five years and he has no intention of securing a patent for the discovery. In another development, malaria specialists from 35 African countries convened at an international workshop in Zimbabwe to compare notes. Participants disparaged financial outlays for the fight against malaria equivalent to 2% of total AIDS funding as insufficient; noted intercountry differences in prevention, diagnosis, and treatment; and found information exchange between anglophone and francophone doctors to be generally poor.
Fowkes, Freya J I; Boeuf, Philippe; Beeson, James G
With increasing malaria control and goals of malaria elimination, many endemic areas are transitioning from high-to-low-to-no malaria transmission. Reductions in transmission will impact on the development of naturally acquired immunity to malaria, which develops after repeated exposure to Plasmodium spp. However, it is currently unclear how declining transmission and malaria exposure will affect the development and maintenance of naturally acquired immunity. Here we review the key processes which underpin this knowledge; the amount of Plasmodium spp. exposure required to generate effective immune responses, the longevity of antibody responses and the ability to mount an effective response upon re-exposure through memory responses. Lastly we identify research priorities which will increase our understanding of how changing transmission will impact on malarial immunity.
Dunachie, Susanna; Hill, Adrian V.S.; Fletcher, Helen A.
A vaccine for malaria is urgently required. The RTS,S vaccine represents major progress, but is only partially effective. Development of the next generation of highly effective vaccines requires elucidation of the protective immune response. Immunity to malaria is known to be complex, and pattern-based approaches such as global gene expression profiling are ideal for understanding response to vaccination and protection against disease. The availability of experimental sporozoite challenge in humans to test candidate malaria vaccines offers a precious opportunity unavailable for other current targets of vaccine research such as HIV, tuberculosis and Ebola. However, a limited number of transcriptional profiling studies in the context of malaria vaccine research have been published to date. This review outlines the background, existing studies, limits and opportunities for gene expression studies to accelerate malaria vaccine research. PMID:26256528
Dunachie, Susanna; Hill, Adrian V S; Fletcher, Helen A
A vaccine for malaria is urgently required. The RTS,S vaccine represents major progress, but is only partially effective. Development of the next generation of highly effective vaccines requires elucidation of the protective immune response. Immunity to malaria is known to be complex, and pattern-based approaches such as global gene expression profiling are ideal for understanding response to vaccination and protection against disease. The availability of experimental sporozoite challenge in humans to test candidate malaria vaccines offers a precious opportunity unavailable for other current targets of vaccine research such as HIV, tuberculosis and Ebola. However, a limited number of transcriptional profiling studies in the context of malaria vaccine research have been published to date. This review outlines the background, existing studies, limits and opportunities for gene expression studies to accelerate malaria vaccine research.
Idris, Zulkarnain Md; Chan, Chim W.; Kongere, James; Gitaka, Jesse; Logedi, John; Omar, Ahmeddin; Obonyo, Charles; Machini, Beatrice Kemunto; Isozumi, Rie; Teramoto, Isao; Kimura, Masatsugu; Kaneko, Akira
Kenya is intensifying its national efforts in malaria control to achieve malaria elimination. Detailed characterization of malaria infection among populations living in the areas where the disease is endemic in Kenya is a crucial priority, especially for planning and evaluating future malaria elimination strategy. This study aimed to investigate the distribution and extent of malaria infection on islands in Lake Victoria of Kenya to aid in designing new interventions for malaria elimination. Five cross-sectional surveys were conducted between January 2012 and August 2014 on four islands (Mfangano, Takawiri, Kibuogi and Ngodhe) in Lake Victoria and a coastal mainland (Ungoye). Malaria prevalence varied significantly among settings: highest in Ungoye, followed by the large island of Mfangano and lowest in the three remaining small islands. Of the 3867 malaria infections detected by PCR, 91.8% were asymptomatic, 50.3% were sub-microscopic, of which 94% were also asymptomatic. We observed geographical differences and age dependency in both proportion of sub-microscopic infections and asymptomatic parasite carriage. Our findings highlighted the local heterogeneity in malaria prevalence on islands and a coastal area in Lake Victoria, and provided support for the inclusion of mass drug administration as a component of the intervention package to eliminate malaria on islands. PMID:27841361
Idris, Zulkarnain Md; Chan, Chim W; Kongere, James; Gitaka, Jesse; Logedi, John; Omar, Ahmeddin; Obonyo, Charles; Machini, Beatrice Kemunto; Isozumi, Rie; Teramoto, Isao; Kimura, Masatsugu; Kaneko, Akira
Kenya is intensifying its national efforts in malaria control to achieve malaria elimination. Detailed characterization of malaria infection among populations living in the areas where the disease is endemic in Kenya is a crucial priority, especially for planning and evaluating future malaria elimination strategy. This study aimed to investigate the distribution and extent of malaria infection on islands in Lake Victoria of Kenya to aid in designing new interventions for malaria elimination. Five cross-sectional surveys were conducted between January 2012 and August 2014 on four islands (Mfangano, Takawiri, Kibuogi and Ngodhe) in Lake Victoria and a coastal mainland (Ungoye). Malaria prevalence varied significantly among settings: highest in Ungoye, followed by the large island of Mfangano and lowest in the three remaining small islands. Of the 3867 malaria infections detected by PCR, 91.8% were asymptomatic, 50.3% were sub-microscopic, of which 94% were also asymptomatic. We observed geographical differences and age dependency in both proportion of sub-microscopic infections and asymptomatic parasite carriage. Our findings highlighted the local heterogeneity in malaria prevalence on islands and a coastal area in Lake Victoria, and provided support for the inclusion of mass drug administration as a component of the intervention package to eliminate malaria on islands.
Kondrashin, A V
Malaria endemic countries in the southeast Asia region include Bangladesh, Bhutan, India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, and Thailand. Population movement and rapid urbanization, both largely caused by unemployment, and environmental deterioration change the malaria pattern. They also increase the incidence of drug-resistant malaria, especially resistance to 4-aminoquinolines. In India, Plasmodium falciparum is linked to the density and distribution of tribals, and, in southern Thailand, rubber tappers have the highest malaria incidence rate (46.29%). Since the population is young and the young are highly sensitive to malaria infection, the region has low community immunity. High malaria priority areas are forests, forested hills, forest fringe areas, developmental project sites, and border areas. High risk groups include infants, young children, pregnant women, and mobile population groups. Malaria incidence is between 2.5-2.8 million cases, and the slide positivity rate is about 3%. P. falciparum constitutes 40% for all malaria cases. In 1988 in India, there were 222 malaria deaths. Malaria is the 7th most common cause of death in Thailand. 3 of the 19 Anopheline species are resistant to at least 1 insecticide, particularly DDT. Posteradication epidemics surfaced in the mid-1970s. Malaria control programs tend to use the primary health care and integration approach to malaria control. Antiparasite measures range from a single-dose of an antimalarial to mass drug administration. Residual spraying continues to be the main strategy of vector control. Some other vector control measures are fish feeding on mosquito larvae, insecticide impregnated mosquito nets, and repellents. Control programs also have health education activities. India allocates the highest percentage of its total health budget to malaria control (21.54%). Few malariology training programs exist in the region. Slowly processed surveillance data limit the countries' ability to
Montosi, E.; Manzoni, S.; Porporato, A.; Montanari, A.
Malaria is a geographically widespread infectious disease that is well known to be affected by climate variability at both seasonal and interannual timescales. In an effort to identify climatic factors that impact malaria dynamics, there has been considerable research focused on the development of appropriate disease models for malaria transmission driven by climatic time series. These analyses have focused largely on variation in temperature and rainfall as direct climatic drivers of malaria dynamics. Here, we further these efforts by considering additionally the role that soil water content may play in driving malaria incidence. Specifically, we hypothesize that hydro-climatic variability should be an important factor in controlling the availability of mosquito habitats, thereby governing mosquito growth rates. To test this hypothesis, we reduce a nonlinear ecohydrological model to a simple linear model through a series of consecutive assumptions and apply this model to malaria incidence data from three South African provinces. Despite the assumptions made in the reduction of the model, we show that soil water content can account for a significant portion of malaria's case variability beyond its seasonal patterns, whereas neither temperature nor rainfall alone can do so. Future work should therefore consider soil water content as a simple and computable variable for incorporation into climate-driven disease models of malaria and other vector-borne infectious diseases.
Schubert, B.; Jahren, H.
Intra-annual records of carbon (δ13C) and oxygen (δ18O) isotope measurements across tree rings reveal significant changes in δ13C and δ18O value across each growing season. We previously found that across a broad range of climate regimes, the seasonal change in δ13C measured within tree rings reflects changes in seasonal precipitation amount, and demonstrated its utility for quantifying seasonal paleo-precipitation from non-permineralized, fossil wood. Here we produce an equation relating intra-ring changes in δ18O to seasonal changes in temperature and precipitation amount, but the equation yields for unknowns (summer and winter precipitation amounts, and cold and warm month mean temperatures). By combining high-resolution δ13C and δ18O records with independent estimates of mean annual temperature and mean annual precipitation, we show how our general, global relationships could be used to quantify seasonal climate information from fossil sites. We validate our approach using high-resolution δ13C and δ18O data from trees growing at five modern sites (Hawaii, Alaska, Norway, Guyana, and Kenya). The reconstructed estimates of seasonal precipitation and temperature showed excellent agreement with the known climate data for each site (precipitation: R2 = 0.98; temperature: R2 = 0.91). These results confirm that across diverse sites and tree species, seasonal climate information can be accurately quantified using a combination of carbon and oxygen intra-ring isotope profiles.
Kanodia, Kamal V; Vanikar, Aruna V; Kute, Vivek Balkrishna; Trivedi, Hargovind L
Malaria remains a major health problem in many parts of the world leading to high morbidity and mortality related to renal dysfunction and relapsing nature of Plasmodium vivax malaria. Acute renal failure occurs commonly in Plasmodium falciparum malaria, although its rare occurrences have been reported in P. vivax malaria also. We reported a rare case of P. vivax malaria monoinfection associated with acute post infectious glomerulonephritis.
Sollai, Sara; de Martino, Maurizio; Galli, Luisa
Data are lacking regarding asymptomatic and symptomatic malaria prevalence in internationally adopted children. Among 20 children from Democratic Republic of the Congo evaluated in Florence, Italy, in April 2016, malaria prevalence was 80%; 50% of infected children had symptomatic malaria. Adopted children from areas of high malaria endemicity should be screened for malaria. PMID:28322706
Background The elimination of malaria in Zanzibar is highly dependent on sustained effective coverage of bed-nets to avoid malaria resurgence. The Health Belief Model (HBM) framework was used to explore the perceptions of malaria and bed-net use after a noticeable reduction in malaria incidence. Methods Nineteen in-depth interviews were conducted with female and male caretakers of children under five in North A district, Zanzibar. Deductive content analysis was used to identify meaning units that were condensed, coded and assigned to pre-determined elements of the HBM. Results Awareness of malaria among caretakers was high but the illness was now seen as easily curable and uncommon. In addition to the perceived advantage of providing protection against malaria, bed-nets were also thought to be useful for avoiding mosquito nuisance, especially during the rainy season when the malaria and mosquito burden is high. The discomfort of sleeping under a net during the hot season was the main barrier that interrupted consistent bed-net usage. The main cue to using a bed-net was high mosquito density, and children were prioritized when it came to bed-net usage. Caretakers had high perceived self-efficacy and did not find it difficult to use bed-nets. Indoor Residual Spraying (IRS), which was recognized as an additional means of mosquito prevention, was not identified as an alternative for bed-nets. A barrier to net ownership was the increasingly high cost of bed-nets. Conclusions Despite the reduction in malaria incidence and the resulting low malaria risk perceptions among caretakers, the benefit of bed-nets as the most proficient protection against mosquito bites upholds their use. This, in combination with the perceived high self-efficacy of caretakers, supports bed-net usage, while seasonality interrupts consistent use. High effective coverage of bed-nets could be further improved by reinforcing the benefits of bed-nets, addressing the seasonal heat barrier by using nets
van Vugt, Michèle; van Beest, Anne; Sicuri, Elisa; van Tulder, Maurits; Grobusch, Martin P
Artemisinin combination treatment is currently the preferred treatment strategy to combat malaria. However, the drug costs are considerably higher than for previously used therapies. This review discusses the cost-effectiveness of current malaria treatment and prophylaxis in endemic and nonendemic countries. For endemic countries, a systematic search for economic evaluations (i.e., cost-effectiveness, cost-utility and cost-benefit analyses) was conducted, looking at the use of Artemisinin combination treatments in children, pregnant women and other adults. In total, 24 studies were identified investigating the cost-effectiveness of malaria treatments with the focus on uncomplicated malaria, severe or prereferral treatment, all in combination with adequate diagnosis, and malaria prevention by intermittent preventive treatment, respectively. In areas with both Plasmodium falciparum and Plasmodium vivax transmission, artemether-lumefantrine and dihydroartemisinin-piperaquine, respectively, are currently the most cost-effective treatment options. Treatment of severe malaria with artesunate is more cost effective compared with treatment with quinine. For patients that live more than 6 h away from an appropriate healthcare facility, prereferral treatment proved to be more cost-effective compared with no prereferral intervention. Cost-effectiveness of intermittent preventive treatment in pregnant women (IPTp) was dependent an clinical attendance. IPT in infants with sulphadoxine-pyrimethamine (SP) is cost effective in sites with high malaria transmission. IPT in children with artesunate (AS + SP), amodiaquine (AQ) + SPQ or SP alone is a cost effective and safe intervention for reducing the burden of malaria in children in areas with markedly seasonal malaria transmission. Although there is a need for it, little is known about the cost-effectiveness of current approaches to malaria therapy in nonendemic countries and the cost-effectiveness of antimalarial chemoprophylaxis.
Katsuragawa, Tony Hiroshi; Gil, Luiz Herman Soares; Tada, Mauro Shugiro; de Almeida e Silva, Alexandre; Costa, Joana D'Arc Neves; da Silva Araújo, Maisa; Escobar, Ana Lúcia; Pereira da Silva, Luiz Hildebrando
The study area in Rondônia was the site of extensive malaria epidemic outbreaks in the 19th and 20th centuries related to environmental impacts, with large immigration flows. The present work analyzes the transmission dynamics of malaria in these areas to propose measures for avoiding epidemic outbreaks due to the construction of two Hydroelectric Power Plants. A population based baseline demographic census and a malaria prevalence follow up were performed in two river side localities in the suburbs of Porto Velho city and in its rural vicinity. The quantification and nature of malaria parasites in clinical patients and asymptomatic parasite carriers were performed using microscopic and Real Time PCR methodologies. Anopheles densities and their seasonal variation were done by monthly captures for defining HBR (hourly biting rate) values. Main results: (i) malaria among residents show the riverside profile, with population at risk represented by children and young adults; (ii) asymptomatic vivax and falciparum malaria parasite carriers correspond to around 15% of adults living in the area; (iii) vivax malaria relapses were responsible for 30% of clinical cases; (iv) malaria risk for the residents was evaluated as 20–25% for vivax and 5–7% for falciparum malaria; (v) anopheline densities shown outdoors HBR values 5 to 10 fold higher than indoors and reach 10.000 bites/person/year; (vi) very high incidence observed in one of the surveyed localities was explained by a micro epidemic outbreak affecting visitors and temporary residents. Temporary residents living in tents or shacks are accessible to outdoors transmission. Seasonal fishermen were the main group at risk in the study and were responsible for a 2.6 fold increase in the malaria incidence in the locality. This situation illustrates the danger of extensive epidemic outbreaks when thousands of workers and secondary immigrant population will arrive attracted by opportunities opened by the Hydroelectric Power
Baird, J K; Basri, H; Weina, P; MaGuire, J D; Barcus, M J; Picarema, H; Elyazar, I R F; Ayomi, E; Sekartuti
Migrants from Java arrive in hyperendemic Papua, Indonesia lacking exposure to endemic malaria. We evaluated records of evacuation to hospital with a diagnosis of severe malaria from a transmigration village in northeastern Papua. During the first 30 months, 198 residents with severe disease were evacuated (7.5 evacuations/100 person-years). During this period the risk of evacuation for adults (> 15 years of age) was 2.8. (95% CI = 2.1-3.8; P < 0.0001) relative to children, despite apparently equal exposure to risk of infection. Relative risk (RR) for adults was greatest during the first 6 months (RR > 16; 95% CI > or = 2.0-129; P = 0.0009), and diminished during the second 6 months (RR = 9.4; 95% CI = 2.7-32.8; P < 0.0001) and the third 6 months (RR = 3.7; 95% CI = 1.7-7.9; P = 0.0004). During the next two 6-month intervals, the RR for adults was 1.6 and 1.5 (95 % CI range 0.8-2.6; P < 0.18). Adults lacking chronic exposure were far more likely to progress to severe disease compared to children during initial exposure, but not after chronic exposure to infection.
Baird, J. K.; Basri, H.; Weina, P.; MaGuire, J. D.; Barcus, M. J.; Picarema, H.; Elyazar, I. R. F.; Ayomi, E.; Sekartuti
Migrants from Java arrive in hyperendemic Papua, Indonesia lacking exposure to endemic malaria. We evaluated records of evacuation to hospital with a diagnosis of severe malaria from a transmigration village in northeastern Papua. During the first 30 months, 198 residents with severe disease were evacuated (7.5 evacuations/100 person-years). During this period the risk of evacuation for adults (> 15 years of age) was 2.8. (95% CI = 2.1-3.8; P < 0.0001) relative to children, despite apparently equal exposure to risk of infection. Relative risk (RR) for adults was greatest during the first 6 months (RR > 16; 95% CI > or = 2.0-129; P = 0.0009), and diminished during the second 6 months (RR = 9.4; 95% CI = 2.7-32.8; P < 0.0001) and the third 6 months (RR = 3.7; 95% CI = 1.7-7.9; P = 0.0004). During the next two 6-month intervals, the RR for adults was 1.6 and 1.5 (95 % CI range 0.8-2.6; P < 0.18). Adults lacking chronic exposure were far more likely to progress to severe disease compared to children during initial exposure, but not after chronic exposure to infection. PMID:12948380
Fontanet, A. L.; Johnston, D. B.; Walker, A. M.; Rooney, W.; Thimasarn, K.; Sturchler, D.; Macdonald, M.; Hours, M.; Wirth, D. F.
In order to assess the risk and predictors of mefloquine resistance we monitored a cohort of 113 patients in eastern Thailand who had been treated for uncomplicated falciparum malaria with a single dose of 15 mg/kg of the drug and followed up for 42 days. The overall treatment failure rate at day 42 was 59.1% (95% confidence interval (CI) = 50%, 68%) with only 2.7% of the patients being lost to follow-up. There were 6.4% RIII, 20.9% RII, 31.8% RI, and 40.9% sensitive responses, based on a modified WHO classification. A low haemoglobin level on the day of treatment and diarrhoea during the first two days after treatment were independent predictors of treatment failure. These findings remained statistically significant in a Cox proportional hazards model, after controlling for other baseline characteristics and adverse effects. Although a history of digestive disorders prior to treatment was associated with diarrhoea on day 2 (P = 0.024), it was in itself not a predictor of treatment failure (adjusted hazard ratio = 1.16; 95% CI = 0.35, 2.14). A total of 60 patients with an R response were hospitalized for 7 days to receive supervised treatment with quinine-tetracycline. Only three had a positive thick smear for asexual forms of Plasmodium falciparum 14 days later, and quinine-tetracycline therefore remains a good alternative treatment for mefloquine-resistant falciparum malaria. PMID:8324857
This publication consists of guidelines to assist health administrators and planners in planning, implementing, and evaluating malaria control programs that reflect the reorientation of the World Health Organization malaria control strategy endorsed by the World Health Assembly. The report stresses approaches to malaria control, describing the recent resurgence of malaria and present constraints on malaria control; prerequisites for implementation of the revised antimalaria strategy; objectives of a malaria control program; factors affecting planning of control programs including epidemiological factors related to the environment, man, the vector, and the parasite; socioeconomic factors; and the use of antimalaria measures in 4 different situations for reduction and prevention of mortality due to malaria, reduction and prevention of mortality and morbidity particularly in high risk groups, reduction of prevalence and endemicity of malaria, or countrywide malaria control aimed ultimately at eradication; program implementation, including definition of targets, interrelationship of the malaria services, general health services, and community, and program implementation in relation to each of the 4 tactical variants; and general principles, operational and epidemiological criteria, and socioeconomic indicators for program evaluation. Factors determining malaria epidemics, outbreaks of malaria during eradication or control campaigns, forecasting and detection of malaria epidemics, and control of epidemics are then discussed. Training in malaria control and advances in antimalaria measures including drugs, immunological methods, antimosquito measures, and biological and genetic approaches to vector control and their potential value are assessed. Program coordination between countries and at regional and global levels and data collection and dissemination for international surveillance are discussed. A series of recommendations is offered for various aspects of malaria
Bousema, Teun; Youssef, Randa M; Cook, Jackie; Cox, Jonathan; Alegana, Victor A; Amran, Jamal; Noor, Abdisalan M; Snow, Robert W; Drakeley, Chris
Areas in which malaria is not highly endemic are suitable for malaria elimination, but assessing transmission is difficult because of lack of sensitivity of commonly used methods. We evaluated serologic markers for detecting variation in malaria exposure in Somalia. Plasmodium falciparum or P. vivax was not detected by microscopy in cross-sectional surveys of samples from persons during the dry (0/1,178) and wet (0/1,128) seasons. Antibody responses against P. falciparum or P. vivax were detected in 17.9% (179/1,001) and 19.3% (202/1,044) of persons tested. Reactivity against P. falciparum was significantly different between 3 villages (p<0.001); clusters of seroreactivity were present. Distance to the nearest seasonal river was negatively associated with P. falciparum (p = 0.028) and P. vivax seroreactivity (p = 0.016). Serologic markers are a promising tool for detecting spatial variation in malaria exposure and evaluating malaria control efforts in areas where transmission has decreased to levels below the detection limit of microscopy.
Peeters Grietens, Koen; Gryseels, Charlotte; Dierickx, Susan; Bannister-Tyrrell, Melanie; Trienekens, Suzan; Uk, Sambunny; Phoeuk, Pisen; Suon, Sokha; Set, Srun; Gerrets, René; Hoibak, Sarah; Muela Ribera, Joan; Hausmann-Muela, Susanna; Tho, Sochantha; Durnez, Lies; Sluydts, Vincent; d’Alessandro, Umberto; Coosemans, Marc; Erhart, Annette
Human population movements currently challenge malaria elimination in low transmission foci in the Greater Mekong Subregion. Using a mixed-methods design, combining ethnography (n = 410 interviews), malariometric data (n = 4996) and population surveys (n = 824 indigenous populations; n = 704 Khmer migrants) malaria vulnerability among different types of mobile populations was researched in the remote province of Ratanakiri, Cambodia. Different structural types of human mobility were identified, showing differential risk and vulnerability. Among local indigenous populations, access to malaria testing and treatment through the VMW-system and LLIN coverage was high but control strategies failed to account for forest farmers’ prolonged stays at forest farms/fields (61% during rainy season), increasing their exposure (p = 0.002). The Khmer migrants, with low acquired immunity, active on plantations and mines, represented a fundamentally different group not reached by LLIN-distribution campaigns since they were largely unregistered (79%) and unaware of the local VMW-system (95%) due to poor social integration. Khmer migrants therefore require control strategies including active detection, registration and immediate access to malaria prevention and control tools from which they are currently excluded. In conclusion, different types of mobility require different malaria elimination strategies. Targeting mobility without an in-depth understanding of malaria risk in each group challenges further progress towards elimination. PMID:26593245
Bomblies, A.; Duchemin, J.; Eltahir, E. A.
We present a coupled hydrology and entomology model for the mechanistic simulation of local-scale response of malaria transmission to hydrological and climatological determinants in semi-arid, desert fringe environments. The model is applied to the Sahel village of Banizoumbou, Niger, to predict interannual variability in malaria vector mosquito populations which lead to variations in malaria transmission. Using a high-resolution, small-scale distributed hydrology model that incorporates remotely-sensed data for land cover and topography, we simulate the formation and persistence of the pools constituting the primary breeding habitat of Anopheles gambiae s.l. mosquitoes, the principal regional malaria vector mosquitoes. An agent-based mosquito population model is coupled to the distributed hydrology model, with aquatic stage and adult stage components. For each individual adult mosquito, the model tracks attributes relevant to population dynamics and malaria transmission, which are updated as mosquitoes interact with their environment, humans, and animals. Weekly field observations were made in 2005 and 2006. The model reproduces mosquito population variability at seasonal and interannual time scales, and highlights individual pool persistence as a dominant control. Future developments to the presented model can be used in the evaluation of impacts of climate change on malaria, as well as the a priori evaluation of environmental management-based interventions.
Deressa, Wakgari; Ali, Ahmed
Background Malaria remains to be the major cause of morbidity and mortality among pregnant women and children in Ethiopia. The aim of this study was to investigate the local perceptions, practices and treatment seeking behaviour for malaria among women with children under the age of five years. Methods This community-based study was conducted in 2003 in an area of seasonal malaria transmission in Adami Tulu District, south-central Ethiopia. Total samples of 2087 rural women with children less than five years of age from 18 rural kebeles (the smallest administrative units) were interviewed about their perceptions and practices regarding malaria. In addition, focus group discussions and in-depth interviews were conducted on similar issues to complement the quantitative data. Results Malaria, locally known as busaa, is perceived as the main health problem in the study area. Mosquitoes are perceived to be the main cause of the disease, and other misperceptions were also widespread. The use of prevention measures was very low. Most mothers were familiar with the main signs and symptoms of mild malaria, and some of them indicated high grade fever, convulsions and mental confusion as a manifestation of severe malaria. Very few households (5.6%) possessed one or two nets. More than 60% of the mothers with recent episodes of malaria received initial treatment from non-public health facilities such as community health workers (CHWs) (40%) and private care providers (21%). Less than 40% of the reported malaria cases among women were treated by public health facilities. Conclusion Malaria was perceived as the main health problem among women and children. The use of malaria preventive measures was low. A significant proportion of the respondents received initial malaria treatments from CHWs, private care providers and public health facilities. Concerted effort is needed to scale-up the distribution of insecticide-treated nets and improve the knowledge of the community about the
Kapilananda, G. M. G.; Samarakoon, Dilhani; Maddevithana, Sashika; Wijesundera, Sulochana; Goonaratne, Lallindra V.; Karunaweera, Nadira D.
Glucose-6-Phosphate Dehydrogenase (G6PD) enzyme deficiency is known to offer protection against malaria and an increased selection of mutant genes in malaria endemic regions is expected. However, anti-malarial drugs such as primaquine can cause haemolytic anaemia in persons with G6PD deficiency. We studied the extent of G6PD deficiency in selected persons attending Teaching Hospitals of Anuradhapura and Kurunegala, two previously high malaria endemic districts in Sri Lanka. A total of 2059 filter-paper blood spots collected between November 2013 and June 2014 were analysed for phenotypic G6PD deficiency using the modified WST-8/1-methoxy PMS method. Each assay was conducted with a set of controls and the colour development assessed visually as well as with a microplate reader at OD450-630nm. Overall, 142/1018 (13.95%) and 83/1041 (7.97%) were G6PD deficient in Anuradhapura and Kurunegala districts respectively. The G6PD prevalence was significantly greater in Anuradhapura when compared to Kurunegala (P<0.0001). Surprisingly, females were equally affected as males in each district: 35/313 (11.18%) males and 107/705 (15.18%) females were affected in Anuradhapura (P = 0.089); 25/313 (7.99%) males and 58/728 (7.97%) females were affected in Kurunegala (P = 0.991). Prevalence was greater among females in Anuradhapura than in Kurunegala (P<0.05), while no such difference was observed between the males (P>0.05). Severe deficiency (<10% normal) was seen among 28/1018 (2.75%) in Anuradhapura (7 males; 21 females) and 17/1041 (1.63%) in Kurunegala (7 males; 10 females). Enzyme activity between 10–30% was observed among 114/1018 (11.20%; 28 males; 86 females) in Anuradhapura while it was 66/1041 (6.34%; 18 males; 48 females) in Kurunegala. Screening and educational programmes for G6PD deficiency are warranted in these high risk areas irrespective of gender for the prevention of disease states related to this condition. PMID:28152025
Birhanie, Meseret; Tessema, Belay; Ferede, Getachew; Endris, Mengistu; Enawgaw, Bamlaku
Background. Malaria and typhoid fever are major public health problems in tropical and subtropical countries. People in endemic areas are at risk of contracting both infections concurrently. Objectives. The study was aimed at determining the prevalence and associated risk factors of malaria, typhoid, and their coinfection among febrile patients. Methods. A cross-sectional study was conducted on 200 febrile patients suspected for malaria and/or typhoid fever from April to May, 2013, at Ayinba Health Center, Northwest Ethiopia. Blood samples were collected for blood culture, Widal test, and blood film preparation. Data were analyzed using SPSS version 20 statistical software. Results. The prevalence of malaria was 36.5% (n = 73). Among these 32 (43.8%), 30 (41.1%) and 11 (15.1%) were positive for P. falciparum, P. vivax, and mixed infections, respectively. The seroprevalence of typhoid fever was 38 (19%), but 1 (0.5%) with blood culture. Malaria typhoid fever coinfection was 13 (6.5%). 2-5-year-old children and poor hand washing habit were significantly associated with malaria and typhoid infection, respectively (P < 0.05). Conclusions. The prevalence of malaria and typhoid fever was found high. Further studies should be done on the other determinants of malaria and typhoid fever coinfection in different seasons and different study areas.
Data from the North Pacific gyre, Bering Sea, and North Atlantic show large seasonal fluctuations in the pCO2 of surface waters. The seasonal variation in these latitudes apparently has a generic pattern: higher surface water pCO2 in winter and lower in summer. Satellite data will eventually help decipher the relative effects of temperature and biological production in the seasonal carbon cycle, but as yet little work has been done on what possible role the seasonality of pCO2 in the high latitudes might have on the average value of atmospheric pCO2. A model is developed that shows the average value for atmospheric pCO2 depends upon the ratio of the rates at which the ocean/atmosphere system moves toward equilibrium values during the summer and winter conditions of the high latitude ocean.
Nowadays, malaria control is planned according to the epidemiological context. Various aspects of malaria have been described in sub-Saharan Africa. We report here entomological data from the coastal area of Benin, West Africa, which has many lakes and lagoons. We carried out a longitudinal study in which we investigated the dynamics of populations of malaria vectors in various zones, the frequency of inoculation in these zones, the infestation rate of the Anopheles gambiae mosquitoes collected, the effect of urbanization on malaria transmission, the effects of inundation and of salinity at mosquito breeding sites. A total of 3, 342 identifications were made on a chromosomal basis. Two species of the Anopheles gambiae complex were detected in the coastal and lagoon areas of Benin: An. melas and An. gambiae ss. The density of the populations of these species was highly dependent on the level of urbanization. In traditional villages on the lagoons (such as Agbalilamè, Djegbadji and Kétonou), the density of An. melas (86. 2%) was much higher than that in more urbanized areas (such as Ladji and Abomey-Calavi) (4.9%). We checked for chromosome polymorphism. We detected a 2Rn1 inversion in An. melas, similar to the 2Rn inversion found in mosquitoes in Gambia and Guinea-Bissau. The frequency of the n1 inversion and the density of An. melas populations were correlated and both seemed to depend on a single factor, salinity. The epidemiological situation with respect to malaria was very heterogeneous in the lagoon area of Benin. In the city of Cotonou, transmission was seasonal, sporozoite indices and the frequency of inoculation were high, in contrast to what would normally be expected in an urban area. In communities built on the beach, the level of transmission was markedly lower: about 5 infected bites per person per year versus 29 infected bites per person in the center of the city. In the traditional fishing villages, a paradoxical situation was observed in which the
Background The widespread use of insecticide-treated nets (LLINs) leads to the development of vector resistance to insecticide. This resistance can reduce the effectiveness of LLIN-based interventions and perhaps reverse progress in reducing malaria morbidity. To prevent such difficulty, it is important to know the real impact of resistance in the effectiveness of mosquito nets. Therefore, an assessment of LLIN efficacy was conducted in malaria prevention among children in high and low resistance areas. Methods The study was conducted in four rural districts and included 32 villages categorized as low or high resistance areas in Plateau Department, south-western Benin. Larvae collection was conducted to measure vector susceptibility to deltamethrin and knockdown resistance (kdr) frequency. In each resistance area, around 500 children were selected to measure the prevalence of malaria infection as well as the prevalence of anaemia associated with the use of LLINs. Results Observed mortalities of Anopheles gambiae s.s population exposed to deltamethrin ranged from 19 to 96%. Knockdown resistance frequency was between 38 and 84%. The prevalence of malaria infection in children under five years was 22.4% (19.9-25.1). This prevalence was 17.3% (14.2-20.9) in areas of high resistance and 27.1% (23.5-31.1) in areas of low resistance (p = 0.04). Eight on ten children that were aged six - 30 months against seven on ten of those aged 31–59 months were anaemic. The anaemia observed in the six to 30-month old children was significantly higher than in the 31–59 month old children (p = 0.00) but no difference associated with resistance areas was observed (p = 0.35). The net use rate was 71%. The risk of having malaria was significantly reduced (p < 0.05) with LLIN use in both low and high resistance areas. The preventive effect of LLINs in high resistance areas was 60% (95% CI: 40–70), and was significantly higher than that observed in low resistance
Neafsey, Daniel E.; Waterhouse, Robert M.; Abai, Mohammad R.; Aganezov, Sergey S.; Alekseyev, Max A.; Allen, James E.; Amon, James; Arcà, Bruno; Arensburger, Peter; Artemov, Gleb; Assour, Lauren A.; Basseri, Hamidreza; Berlin, Aaron; Birren, Bruce W.; Blandin, Stephanie A.; Brockman, Andrew I.; Burkot, Thomas R.; Burt, Austin; Chan, Clara S.; Chauve, Cedric; Chiu, Joanna C.; Christensen, Mikkel; Costantini, Carlo; Davidson, Victoria L.M.; Deligianni, Elena; Dottorini, Tania; Dritsou, Vicky; Gabriel, Stacey B.; Guelbeogo, Wamdaogo M.; Hall, Andrew B.; Han, Mira V.; Hlaing, Thaung; Hughes, Daniel S.T.; Jenkins, Adam M.; Jiang, Xiaofang; Jungreis, Irwin; Kakani, Evdoxia G.; Kamali, Maryam; Kemppainen, Petri; Kennedy, Ryan C.; Kirmitzoglou, Ioannis K.; Koekemoer, Lizette L.; Laban, Njoroge; Langridge, Nicholas; Lawniczak, Mara K.N.; Lirakis, Manolis; Lobo, Neil F.; Lowy, Ernesto; MacCallum, Robert M.; Mao, Chunhong; Maslen, Gareth; Mbogo, Charles; McCarthy, Jenny; Michel, Kristin; Mitchell, Sara N.; Moore, Wendy; Murphy, Katherine A.; Naumenko, Anastasia N.; Nolan, Tony; Novoa, Eva M.; O'Loughlin, Samantha; Oringanje, Chioma; Oshaghi, Mohammad A.; Pakpour, Nazzy; Papathanos, Philippos A.; Peery, Ashley N.; Povelones, Michael; Prakash, Anil; Price, David P.; Rajaraman, Ashok; Reimer, Lisa J.; Rinker, David C.; Rokas, Antonis; Russell, Tanya L.; Sagnon, N'Fale; Sharakhova, Maria V.; Shea, Terrance; Simão, Felipe A.; Simard, Frederic; Slotman, Michel A.; Somboon, Pradya; Stegniy, Vladimir; Struchiner, Claudio J.; Thomas, Gregg W.C.; Tojo, Marta; Topalis, Pantelis; Tubio, José M.C.; Unger, Maria F.; Vontas, John; Walton, Catherine; Wilding, Craig S.; Willis, Judith H.; Wu, Yi-Chieh; Yan, Guiyun; Zdobnov, Evgeny M.; Zhou, Xiaofan; Catteruccia, Flaminia; Christophides, George K.; Collins, Frank H.; Cornman, Robert S.; Crisanti, Andrea; Donnelly, Martin J.; Emrich, Scott J.; Fontaine, Michael C.; Gelbart, William; Hahn, Matthew W.; Hansen, Immo A.; Howell, Paul I.; Kafatos, Fotis C.; Kellis, Manolis; Lawson, Daniel; Louis, Christos; Luckhart, Shirley; Muskavitch, Marc A.T.; Ribeiro, José M.; Riehle, Michael A.; Sharakhov, Igor V.; Tu, Zhijian; Zwiebel, Laurence J.; Besansky, Nora J.
Variation in vectorial capacity for human malaria among Anopheles mosquito species is determined by many factors, including behavior, immunity, and life history. To investigate the genomic basis of vectorial capacity and explore new avenues for vector control, we sequenced the genomes of 16 anopheline mosquito species from diverse locations spanning ~100 million years of evolution. Comparative analyses show faster rates of gene gain and loss, elevated gene shuffling on the X chromosome, and more intron losses, relative to Drosophila. Some determinants of vectorial capacity, such as chemosensory genes, do not show elevated turnover, but instead diversify through protein-sequence changes. This dynamism of anopheline genes and genomes may contribute to their flexible capacity to take advantage of new ecological niches, including adapting to humans as primary hosts. PMID:25554792
Neafsey, Daniel E; Waterhouse, Robert M; Abai, Mohammad R; Aganezov, Sergey S; Alekseyev, Max A; Allen, James E; Amon, James; Arcà, Bruno; Arensburger, Peter; Artemov, Gleb; Assour, Lauren A; Basseri, Hamidreza; Berlin, Aaron; Birren, Bruce W; Blandin, Stephanie A; Brockman, Andrew I; Burkot, Thomas R; Burt, Austin; Chan, Clara S; Chauve, Cedric; Chiu, Joanna C; Christensen, Mikkel; Costantini, Carlo; Davidson, Victoria L M; Deligianni, Elena; Dottorini, Tania; Dritsou, Vicky; Gabriel, Stacey B; Guelbeogo, Wamdaogo M; Hall, Andrew B; Han, Mira V; Hlaing, Thaung; Hughes, Daniel S T; Jenkins, Adam M; Jiang, Xiaofang; Jungreis, Irwin; Kakani, Evdoxia G; Kamali, Maryam; Kemppainen, Petri; Kennedy, Ryan C; Kirmitzoglou, Ioannis K; Koekemoer, Lizette L; Laban, Njoroge; Langridge, Nicholas; Lawniczak, Mara K N; Lirakis, Manolis; Lobo, Neil F; Lowy, Ernesto; MacCallum, Robert M; Mao, Chunhong; Maslen, Gareth; Mbogo, Charles; McCarthy, Jenny; Michel, Kristin; Mitchell, Sara N; Moore, Wendy; Murphy, Katherine A; Naumenko, Anastasia N; Nolan, Tony; Novoa, Eva M; O'Loughlin, Samantha; Oringanje, Chioma; Oshaghi, Mohammad A; Pakpour, Nazzy; Papathanos, Philippos A; Peery, Ashley N; Povelones, Michael; Prakash, Anil; Price, David P; Rajaraman, Ashok; Reimer, Lisa J; Rinker, David C; Rokas, Antonis; Russell, Tanya L; Sagnon, N'Fale; Sharakhova, Maria V; Shea, Terrance; Simão, Felipe A; Simard, Frederic; Slotman, Michel A; Somboon, Pradya; Stegniy, Vladimir; Struchiner, Claudio J; Thomas, Gregg W C; Tojo, Marta; Topalis, Pantelis; Tubio, José M C; Unger, Maria F; Vontas, John; Walton, Catherine; Wilding, Craig S; Willis, Judith H; Wu, Yi-Chieh; Yan, Guiyun; Zdobnov, Evgeny M; Zhou, Xiaofan; Catteruccia, Flaminia; Christophides, George K; Collins, Frank H; Cornman, Robert S; Crisanti, Andrea; Donnelly, Martin J; Emrich, Scott J; Fontaine, Michael C; Gelbart, William; Hahn, Matthew W; Hansen, Immo A; Howell, Paul I; Kafatos, Fotis C; Kellis, Manolis; Lawson, Daniel; Louis, Christos; Luckhart, Shirley; Muskavitch, Marc A T; Ribeiro, José M; Riehle, Michael A; Sharakhov, Igor V; Tu, Zhijian; Zwiebel, Laurence J; Besansky, Nora J
Variation in vectorial capacity for human malaria among Anopheles mosquito species is determined by many factors, including behavior, immunity, and life history. To investigate the genomic basis of vectorial capacity and explore new avenues for vector control, we sequenced the genomes of 16 anopheline mosquito species from diverse locations spanning ~100 million years of evolution. Comparative analyses show faster rates of gene gain and loss, elevated gene shuffling on the X chromosome, and more intron losses, relative to Drosophila. Some determinants of vectorial capacity, such as chemosensory genes, do not show elevated turnover but instead diversify through protein-sequence changes. This dynamism of anopheline genes and genomes may contribute to their flexible capacity to take advantage of new ecological niches, including adapting to humans as primary hosts.
Dhingra, Neeraj; Jha, Prabhat; Sharma, Vinod P; Cohen, Alan A; Jotkar, Raju M; Rodriguez, Peter S; Bassani, Diego G; Suraweera, Wilson; Laxminaryan, Ramanan; Peto, Richard
Summary Background Malaria, a non-fatal disease if detected promptly and treated properly, still causes many deaths in malaria-endemic countries with limited healthcare facilities. National malaria mortality rates are, however, particularly difficult to assess reliably in such countries, as any fevers reliably diagnosed as malaria are likely therefore to be cured. Hence, most malaria deaths are from undiagnosed malaria, which may be misattributed in retrospective enquiries to other febrile causes of death, or vice-versa. Aim To estimate plausible ranges of malaria mortality in India, the most populous country where it remains common. Methods Nationally representative retrospective study of 122,000 deaths during 2001-03 in 6671 areas. Full-time non-medical field workers interviewed families or other respondents about each death, obtaining a half-page narrative plus answers to specific questions about the severity and course of any fevers. Each field report was scanned and emailed to two of 130 trained physicians, who independently coded underlying causes, with discrepancies resolved either via anonymous reconciliation or, failing that, adjudication. Findings Of all coded deaths at ages 1 month to 70 years, 3.6% (2681/75,342) were attributed to malaria. Of these, 2419 (90%) were rural and 2311 (86%) were not in any healthcare facility. Malaria-attributed death rates correlated geographically with local malaria transmission rates derived independently from the Indian malaria control programme, and rose after the wet season began. The adjudicated results suggest 205,000 malaria deaths per year in India before age 70 (55,000 in early childhood, 30,000 at ages 5-14, 120,000 at ages 15-69); cumulative probability 1.8% of death from malaria before age 70. Plausible upper and lower bounds (based only on the initial coding) were 125,000 to 277,000. Interpretation Despite inevitable uncertainty as to which unattended febrile deaths are from malaria, even the lower bound
Pope, Kevin O.
Malaria is the most important vector-borne tropical disease (Collins and Paskewitz, 1995) and there is no simple and universally applicable form of vector control. While new methods such as malaria vaccine or genetic manipulation of mosquitoes are being explored in the laboratories, the need for more field research on malaria transmission remains very strong. For the foreseeable future many malaria programs must focus on controlling the vector, the anopheline mosquito, often under the specter of shrinking budgets. Therefore information on which human populations are at the greatest risk is especially valuable when allocating scarce resources. The goal of the Radar Monitoring of Wetlands for Malaria Control Project is to demonstrate the feasibility of using Radarsat or other comparable satellite radar imaging systems to determine where and when human populations are at greatest risk for contracting malaria. The study area is northern Belize, a region with abundant wetlands and a potentially serious malaria problem. A key aspect of this study is the analysis of multi-temporal satellite imagery to track seasonal flooding of anopheline mosquito breeding sites. Radarsat images of the test site in Belize have been acquired one to three times a month over the last year, however,, to date only one processed image has been received from the Alaska SAR Facility for analysis. Therefore analysis at this stage is focussed on determining the radar backscatter characteristics of known anopheline breeding sites, with future work to be dedicated toward seasonal changes.
This article gives an overview of some of the ongoing challenges that are faced in the prevention, diagnosis and treatment of malaria. Malaria causes approximately 881,000 deaths every year, with nine out of ten deaths occurring in sub-Saharan Africa. In addition to the human burden of malaria, the economic burden is vast. It is thought to cost African countries more than US$12 billion every year in direct losses. However, great progress in malaria control has been made in some highly endemic countries. Vector control is assuming a new importance with the significant reductions in malaria burden achieved using combined malaria control interventions in countries such as Zanzibar, Zambia and Rwanda. The proportion of patients treated for malaria who have a confirmed diagnosis is low in Africa compared with other regions of the world, with the result that anti-malarials could be used to treat patients without malaria, especially in areas where progress has been made in reducing the malaria burden and malaria epidemiology is changing. Inappropriate administration of anti-malarials could contribute to the spread of resistance and incurs unnecessary costs. Parasite resistance to almost all commonly used anti-malarials has been observed in the most lethal parasite species, Plasmodium falciparum. This has presented a major barrier to successful disease management in malaria-endemic areas. ACT (artemisinin-based combination therapy) has made a significant contribution to malaria control and to reducing disease transmission through reducing gametocyte carriage. Administering ACT to infants and small children can be difficult and time consuming. Specially formulating anti-malarials for this vulnerable population is vital to ease administration and help ensure that an accurate dose is received. Education of healthworkers and communities about malaria prevention, diagnosis and treatment is a vital component of effective case management, especially as diagnostic policies change
Luong, Kyphuong; Dunkel, Florence V; Coulibaly, Keriba; Beckage, Nancy E
Larval management of the malaria vector, Anopheles gambiae Giles s.s., has been successful in reducing disease transmission. However, pesticides are not affordable to farmers in remote villages in Mali, and in other material resource poor countries. Insect resistance to insecticides and nontarget toxicity pose additional problems. Neem (Azadirachta indica A. Juss) is a tree with many beneficial, insect bioactive compounds, such as azadirachtin. We tested the hypothesis that neem leaf slurry is a sustainable, natural product, anopheline larvicide. A field study conducted in Sanambele (Mali) in 2010 demonstrated neem leaf slurry can work with only the available tools and resources in the village. Laboratory bioassays were conducted with third instar An. gambiae and village methods were used to prepare the leaf slurry. Experimental concentration ranges were 1,061-21,224 mg/L pulverized neem leaves in distilled water. The 50 and 90% lethal concentrations at 72 h were 8,825 mg/L and 15,212 mg/L, respectively. LC concentrations were higher than for other parts of the neem tree when compared with previous published studies because leaf slurry preparation was simplified by omitting removal of fibrous plant tissue. Using storytelling as a medium of knowledge transfer, villagers combined available resources to manage anopheline larvae. Preparation of neem leaf slurries is a sustainable approach which allows villagers to proactively reduce mosquito larval density within their community as part of an integrated management system.
Yamana, T. K.; Eltahir, E. A.
Early warnings of malaria transmission allow health officials to better prepare for future epidemics. Monitoring rainfall is recognized as an important part of malaria early warning systems, as outlined by the Roll Back Malaria Initiative. The Hydrology, Entomology and Malaria Simulator (HYDREMATS) is a mechanistic model that relates rainfall to malaria transmission, and could be used to provide early warnings of malaria epidemics. HYDREMATS is used to make predictions of mosquito populations and vectorial capacity for 2005, 2006, and 2007 in Banizoumbou village in western Niger. HYDREMATS is forced by observed rainfall, followed by a rainfall prediction based on the seasonal mean rainfall for a period two or four weeks into the future. Predictions made using this method provided reasonable estimates of mosquito populations and vectorial capacity, two to four weeks in advance. The predictions were significantly improved compared to those made when HYDREMATS was forced with seasonal mean rainfall alone.
Mboera, Leonard E G; Shayo, Elizabeth H; Senkoro, Kesheni P; Rumisha, Susan F; Mlozi, Malongo R S; Mayala, Benjamin K
This study was carried out to determine knowledge, perceptions and practices of farming communities on linkages between agriculture and malaria in Mvomero District in Tanzania. A total of 661 adult males and females were interviewed using a structured questionnaire. Most respondents (85.6%) were engaged in crop production. Significantly, a larger proportion (55.2%) of the respondents had primary school education (P<0.001). Majority (88.2%) respondents described malaria as the most important public health problem. However, only 48.2% of the respondents had high knowledge of malaria. The level of knowledge on malaria was associated with level of education of the respondent. Those who had attended at least primary school education were more knowledgeable that those without formal education. A significantly larger proportion (67%) of the respondents experienced most malaria episodes during the rainy season (P<0.001). Respondents with low knowledge on malaria experienced 2.3 times more malaria cases in their households than those with higher knowledge. Respondents with low knowledge preferred to seek care from health facilities (OR: 7.28) than those with high knowledge (OR: 0.15). Rice farming was significantly associated with malaria transmission compared to either maize or sugarcane farming (P<0.001). Cattle, sheep and goats were the domestic animals most frequently incriminated to create aquatic habitats for mosquito breeding. Householders with formal education (OR: 4.6, CI: 1.33-15.89, P-value=0.016) and higher knowledge (OR: 1.7, CI: 1.15-2.55, P-value=0.008) reported to incur large losses when having a malaria case than those without education/low knowledge. Majority (60.2%) of the respondent owned at least an insecticide treated mosquito net (ITN). Respondents with higher knowledge of malaria were likely to own at least an ITN than those with low knowledge (P<0.001). In conclusion, the knowledge on malaria and its linkage with agriculture among farming
Hung, Wen-Shin; Hu, Susan C; Hsu, Yu-Chen; Chen, Kwo-Liang; Chen, Kou-Huang; Yu, Mei-Ching; Chen, Kow-Tong
The aim of this study was to investigate the predictors of anti-malaria preventive measures (AMPMs) among Taiwan immigrants returning to their country of origin using the Health Belief Model (HBM). Between March and May 2011, all permanent immigrants originating from malaria-endemic countries, attended by either the Taipei or Tainan Immigrant Service Center, Taiwan, and who reported a history of returning to their country of origin within the preceding year during the malarious season in their country of origin were enrolled in the study. Complete information was collected from 316 immigrants, with a response rate of 87% (316/364). The mean age of the subjects was 38.1 years (SD = 9.9). The majority (70%) of participants did not receive travel information through a pre-travel consultation; more than 40% reported that they did not use measures to prevent insect bites. Multiple regression analyses revealed that Chinese proficiency, travel consultation before travel, lower perceived susceptibility to malaria, higher perceived severity of malaria infection, higher perceived benefit for taking measures, and higher self-efficacy for taking measures significantly predicted the use of AMPMs during the return to their country of origin (R(2) = 0.20; F = 50.42; P < 0.001). A high proportion of immigrants were not using appropriate AMPMs when they returned to their country. Educational approaches should be targeted toward immigrants who return to visit their country of origin.
Britton, Sumudu; Cheng, Qin; Grigg, Matthew J.; Poole, Catherine B.; Pasay, Cielo; William, Timothy; Fornace, Kimberley; Anstey, Nicholas M.; Sutherland, Colin J.; Drakeley, Chris; McCarthy, James S.
Introduction Plasmodium vivax malaria has a wide geographic distribution and poses challenges to malaria elimination that are likely to be greater than those of P. falciparum. Diagnostic tools for P. vivax infection in non-reference laboratory settings are limited to microscopy and rapid diagnostic tests but these are unreliable at low parasitemia. The development and validation of a high-throughput and sensitive assay for P. vivax is a priority. Methods A high-throughput LAMP assay targeting a P. vivax mitochondrial gene and deploying colorimetric detection in a 96-well plate format was developed and evaluated in the laboratory. Diagnostic accuracy was compared against microscopy, antigen detection tests and PCR and validated in samples from malaria patients and community controls in a district hospital setting in Sabah, Malaysia. Results The high throughput LAMP-P. vivax assay (HtLAMP-Pv) performed with an estimated limit of detection of 1.4 parasites/ μL. Assay primers demonstrated cross-reactivity with P. knowlesi but not with other Plasmodium spp. Field testing of HtLAMP-Pv was conducted using 149 samples from symptomatic malaria patients (64 P. vivax, 17 P. falciparum, 56 P. knowlesi, 7 P. malariae, 1 mixed P. knowlesi/P. vivax, with 4 excluded). When compared against multiplex PCR, HtLAMP-Pv demonstrated a sensitivity for P. vivax of 95% (95% CI 87–99%); 61/64), and specificity of 100% (95% CI 86–100%); 25/25) when P. knowlesi samples were excluded. HtLAMP-Pv testing of 112 samples from asymptomatic community controls, 7 of which had submicroscopic P. vivax infections by PCR, showed a sensitivity of 71% (95% CI 29–96%; 5/7) and specificity of 93% (95% CI87-97%; 98/105). Conclusion This novel HtLAMP-P. vivax assay has the potential to be a useful field applicable molecular diagnostic test for P. vivax infection in elimination settings. PMID:26870958
Wong, Dawn M.; Li, Jianyong; Chen, Qiao-Hong; Han, Qian; Mutunga, James M.; Wysinski, Ania; Anderson, Troy D.; Ding, Haizhen; Carpenetti, Tiffany L.; Verma, Astha; Islam, Rafique; Paulson, Sally L.; Lam, Polo C.-H.; Totrov, Maxim; Bloomquist, Jeffrey R.; Carlier, Paul R.
Acetylcholinesterase (AChE) is a proven target for control of the malaria mosquito (Anopheles gambiae). Unfortunately, a single amino acid mutation (G119S) in An. gambiae AChE-1 (AgAChE) confers resistance to the AChE inhibitors currently approved by the World Health Organization for indoor residual spraying. In this report, we describe several carbamate inhibitors that potently inhibit G119S AgAChE and that are contact-toxic to carbamate-resistant An. gambiae. PCR-RFLP analysis was used to confirm that carbamate-susceptible G3 and carbamate-resistant Akron strains of An. gambiae carry wild-type (WT) and G119S AChE, respectively. G119S AgAChE was expressed and purified for the first time, and was shown to have only 3% of the turnover number (kcat) of the WT enzyme. Twelve carbamates were then assayed for inhibition of these enzymes. High resistance ratios (>2,500-fold) were observed for carbamates bearing a benzene ring core, consistent with the carbamate-resistant phenotype of the G119S enzyme. Interestingly, resistance ratios for two oxime methylcarbamates, and for five pyrazol-4-yl methylcarbamates were found to be much lower (4- to 65-fold). The toxicities of these carbamates to live G3 and Akron strain An. gambiae were determined. As expected from the enzyme resistance ratios, carbamates bearing a benzene ring core showed low toxicity to Akron strain An. gambiae (LC50>5,000 μg/mL). However, one oxime methylcarbamate (aldicarb) and five pyrazol-4-yl methylcarbamates (4a–e) showed good to excellent toxicity to the Akron strain (LC50 = 32–650 μg/mL). These results suggest that appropriately functionalized “small-core” carbamates could function as a resistance-breaking anticholinesterase insecticides against the malaria mosquito. PMID:23049714
... CDCâs Malaria Maps are another reference to help locate areas with malaria. Conduct an individualized risk assessment Prevention of malaria involves a balance between ensuring that all people who will be at risk of infection use ...
Ganguly, Swagata; Saha, Pabitra; Guha, Subhasish K; Biswas, Asit; Das, Sonali; Kundu, Pratip K; Maji, Ardhendu K
Asymptomatic infection by Plasmodium falciparum is an important obstacle to eliminating malaria. Asymptomatic carriers do not seek treatment for infection, and therefore they become a reservoir for the parasite. For this reason, these carriers pose a real public health risk. The systematic identification and treatment of asymptomatic infections should reduce the parasite reservoir. A large reduction in this pool will lower the chance of transmission of the disease. In this study, we screened a tribal population of 1,040 individuals in the Purulia district of West Bengal by using a dual-antigen rapid diagnostic kit (RDK), microscopy, and species-specific PCR. All positive individuals were treated with artemisinin-based combination therapy (ACT) (artesunate plus sulfadoxine-pyrimethamine) and followed for 42 days. Polymorphisms in candidate genes were screened by DNA sequencing. A significant proportion (8.4%) of the study population was infected with P. falciparum but showed no clinical manifestations. The PCR method was more sensitive in detecting infection than the RDK or microscopy. The efficacy of the ACT was 97%. In the pfcrt gene, the mutation K76T (the mutated amino acid is indicated by bold type) was found in 100% of the cases. In the pfmdr1 gene, the mutations N86Y and Y184F were noted in 55.5% and 11% of the cases, respectively. Six different haplotypes were identified in the pfdhfr-pfdhps genes. Most importantly, the quintuple mutant A(16)I(51)R(59)N(108)I(164)-S(436)G(437)E(540)A(581)A(613) was found in 10% of the isolates, which is potentially important for the development of sulfadoxine-pyrimethamine resistance. A significant proportion of the study population harboring P. falciparum does not seek treatment and therefore serves as a reservoir for the parasite, maintaining the natural cycle. If the National Vector Borne Disease Control Programme (NVBDCP) of India is to eliminate malaria, then this hidden parasite burden needs to be addressed properly
Eisele, Thomas P; Keating, Joseph; Bennett, Adam; Londono, Berlin; Johnson, Dawn; Lafontant, Christina; Krogstad, Donald J
We conducted a population-based survey to estimate the prevalence of Plasmodium falciparum infection among persons older than 1 month in the Artibonite Valley of Haiti during the high malaria transmission season in 2006. Results from PCR for 714 persons showed a prevalence of 3.1% for P. falciparum infection.
Patel, K.; Reinholtz, W.; Robinson, W. J.
The evolution of a high speed spacecraft simulator (HSS) is discussed from development and operations perspectives. The HSS is a series of simulators capable of modeling the spacecraft and its subsystems at different levels. The HSS was developed for the validation of the Galileo low gain antenna mission's flight software. Due to the successful performance of the HSS in assisting with the flight software validation, additional Galileo validation applications were identified. These applications include the modeling of other onboard data systems, such as the command and data subsystem and the attitude and articulation control subsystem. The HSS architecture, which consists of a number of components, is described and the operational use of the system is outlined.
Liang, Shiwei; Li, Weixin; Zhang, Yang; Tang, Xiaolong; He, Jianzheng; Bai, Yucheng; Li, Dongqin; Wang, Yan; Chen, Qiang
Seasonal acclimatization is important for animals to live optimally in the varying environment. Phrynocephalus vlangalii, a species of lizard endemic in China, distributes on Qinghai-Tibet Plateau ranging from 2000 to 4600m above sea level. To dissect how this lizard mediate metabolism to adapt various season, the preferred body temperature (Tb), standard metabolic rate (SMR), mitochondrial respiration rates and activities of four metabolic enzymes in this species were tested in different seasons (spring, summer, and autumn). The results showed that the preferred Tb was the lowest in spring and the highest in summer. SMR, maximal mitochondrial respiration rates in liver and skeletal muscle were the highest in spring. Similarly, higher activities of lactate dehydrogenase (LDH), citrate synthase (CS) and cytochrome c oxidase (CCO) activities of liver and skeletal muscle were observed in spring. However, β-hydroxyacyl coenzyme A dehydrogenase (HOAD) activities of liver and skeletal muscle were higher in autumn. On the whole, seasonal variation of metabolism is the highest in spring and the lowest in summer. Seasonal variation of metabolism is the opposite of preferred body temperature, this may be one of the mechanisms to adapt to the environment in P. vlangalii. Our results suggested that P. vlangalii at high altitude has certain adaptive characteristics on metabolism in different seasons.
Cairns, Matthew; Ghani, Azra; Okell, Lucy; Gosling, Roly; Carneiro, Ilona; Anto, Francis; Asoala, Victor; Owusu-Agyei, Seth; Greenwood, Brian; Chandramohan, Daniel; Milligan, Paul
Background Intermittent preventive treatment in infants (IPTi) with sulfadoxine-pyrimethamine (SP) is recommended by WHO where malaria incidence in infancy is high and SP resistance is low. The current delivery strategy is via routine Expanded Program on Immunisation contacts during infancy (EPI-IPTi). However, improvements to this approach may be possible where malaria transmission is seasonal, or where the malaria burden lies mainly outside infancy. Methods and Findings A mathematical model was developed to estimate the protective efficacy (PE) of IPT against clinical malaria in children aged 2-24 months, using entomological and epidemiological data from an EPI-IPTi trial in Navrongo, Ghana to parameterise the model. The protection achieved by seasonally-targeted IPT in infants (sIPTi), seasonal IPT in children (sIPTc), and by case-management with long-acting artemisinin combination therapies (LA-ACTs) was predicted for Navrongo and for sites with different transmission intensity and seasonality. In Navrongo, the predicted PE of sIPTi was 26% by 24 months of age, compared to 16% with EPI-IPTi. sIPTc given to all children under 2 years would provide PE of 52% by 24 months of age. Seasonally-targeted IPT retained its advantages in a range of transmission patterns. Under certain circumstances, LA-ACTs for case-management may provide similar protection to EPI-IPTi. However, EPI-IPTi or sIPT combined with LA-ACTs would be substantially more protective than either strategy used alone. Conclusion Delivery of IPT to infants via the EPI is sub-optimal because individuals are not protected by IPT at the time of highest malaria risk, and because older children are not protected. Alternative delivery strategies to the EPI are needed where transmission varies seasonally or the malaria burden extends beyond infancy. Long-acting ACTs may also make important reductions in malaria incidence. However, delivery systems must be developed to ensure that both forms of chemoprevention
Orjuela-Sánchez, Pamela; Brandi, Michelle C; Ferreira, Marcelo U
Microsatellites have been increasingly used to investigate the population structure of malaria parasites, to map genetic loci contributing to phenotypes such as drug resistance and virulence in laboratory crosses and genome-wide association studies and to distinguish between treatment failures and new infections in clinical trials. Here, we provide optimized protocols for genotyping highly polymorphic microsatellites sampled from across the genomes of the human malaria parasites Plasmodium falciparum and P. vivax that have been extensively used in research laboratories worldwide.
Jute, Stefanus; Toovey, Stephen
A questionnaire survey of malaria chemoprophylaxis knowledge, attitudes, and practices of 90 expatriates on a Mali mine yielded 68 (75.5%) responses. A total of 49 (72%) subjects took perennial chemoprophylaxis, 6 (9%) were children <5 years. Out of 68, 13 (19%) took chemoprophylaxis during the high transmission season only and 10 (15%) never took chemoprophylaxis. Reasons advanced for not taking chemoprophylaxis were concern over adverse effects, presumed immunity from long term residence in Africa, and on site access to quality medical care. Chemoprophylactics used were: atovaquone-proguanil 1 (2%); chloroquine and proguanil 15 (30%); doxycycline 16 (33%); mefloquine 17 (35%). Thirteen out of 49 (27%) subjects admitted to missing chemoprophylaxis doses and 15/68 (22%) had suffered malaria while on chemoprophylaxis. Fifteen out of 49 (31%) low season chemoprophylaxis users and 4/19 (21%) non-users contracted low season malaria (chi(2), p=0.63). A total of 46 (68%) used insect repellants, 50 (74%) used insecticide sprays or coils in rooms, 9 (13%) slept under insecticide treated nets. Malaria control in expatriates requires improvement; additional strategies for consideration that require reduced compliance requirements by expatriates are suggested, including residual spraying, seasonal chemoprophylaxis use, and emergency stand by medication.
Xu, Weiping; Morris, Ulrika; Aydin-Schmidt, Berit; Msellem, Mwinyi I; Shakely, Delér; Petzold, Max; Björkman, Anders; Mårtensson, Andreas
A prerequisite for reliable detection of low-density Plasmodium infections in malaria pre-elimination settings is the availability of ultra-sensitive and high-throughput molecular tools. We developed a SYBR Green real-time PCR restriction fragment length polymorphism assay (cytb-qPCR) targeting the cytochrome b gene of the four major human Plasmodium species (P. falciparum, P. vivax, P. malariae, and P. ovale) for parasite detection and species determination with DNA extracted from dried blood spots collected on filter paper. The performance of cytb-qPCR was first compared against four reference PCR methods using serially diluted Plasmodium samples. The detection limit of the cytb-qPCR was 1 parasite/μl (p/μl) for P. falciparum and P. ovale, and 2 p/μl for P. vivax and P. malariae, while the reference PCRs had detection limits of 0.5-10 p/μl. The ability of the PCR methods to detect low-density Plasmodium infections was then assessed using 2977 filter paper samples collected during a cross-sectional survey in Zanzibar, a malaria pre-elimination setting in sub-Saharan Africa. Field samples were defined as 'final positive' if positive in at least two of the five PCR methods. Cytb-qPCR preformed equal to or better than the reference PCRs with a sensitivity of 100% (65/65; 95%CI 94.5-100%) and a specificity of 99.9% (2910/2912; 95%CI 99.7-100%) when compared against 'final positive' samples. The results indicate that the cytb-qPCR may represent an opportunity for improved molecular surveillance of low-density Plasmodium infections in malaria pre-elimination settings.
Samuel, M.D.; Hobbelen, P.H.F.; Decastro, F.; Ahumada, J.A.; Lapointe, D.A.; Atkinson, C.T.; Woodworth, B.L.; Hart, P.J.; Duffy, D.C.
We developed an epidemiological model of avian malaria (Plasmodium relictum) across an altitudinal gradient on the island of Hawaii that includes the dynamics of the host, vector, and parasite. This introduced mosquito-borne disease is hypothesized to have contributed to extinctions and major shifts in the altitudinal distribution of highly susceptible native forest birds. Our goal was to better understand how biotic and abiotic factors influence the intensity of malaria transmission and impact on susceptible populations of native Hawaiian forest birds. Our model illustrates key patterns in the malaria-forest bird system: high malaria transmission in low-elevation forests with minor seasonal or annual variation in infection;episodic transmission in mid-elevation forests with site-to-site, seasonal, and annual variation depending on mosquito dynamics;and disease refugia in high-elevation forests with only slight risk of infection during summer. These infection patterns are driven by temperature and rainfall effects on parasite incubation period and mosquito dynamics across an elevational gradient and the availability of larval habitat, especially in mid-elevation forests. The results from our model suggest that disease is likely a key factor in causing population decline or restricting the distribution of many susceptible Hawaiian species and preventing the recovery of other vulnerable species. The model also provides a framework for the evaluation of factors influencing disease transmission and alternative disease control programs, and to evaluate the impact of climate change on disease cycles and bird populations. ??2011 by the Ecological Society of America.
Tosta, Carlos Eduardo
Malaria emerges from a disequilibrium of the system 'human-plasmodium-mosquito' (HPM). If the equilibrium is maintained, malaria does not ensue and the result is asymptomatic plasmodium infection. The relationships among the components of the system involve coadaptive linkages that lead to equilibrium. A vast body of evidence supports this assumption, including the strategies involved in the relationships between plasmodium and human and mosquito immune systems, and the emergence of resistance of plasmodia to antimalarial drugs and of mosquitoes to insecticides. Coadaptive strategies for malaria control are based on the following principles: (1) the system HPM is composed of three highly complex and dynamic components, whose interplay involves coadaptive linkages that tend to maintain the equilibrium of the system; (2) human and mosquito immune systems play a central role in the coadaptive interplay with plasmodium, and hence, in the maintenance of the system's equilibrium; the under- or overfunction of human immune system may result in malaria and influence its severity; (3) coadaptation depends on genetic and epigenetic phenomena occurring at the interfaces of the components of the system, and may involve exchange of infectrons (genes or gene fragments) between the partners; (4) plasmodia and mosquitoes have been submitted to selective pressures, leading to adaptation, for an extremely long while and are, therefore, endowed with the capacity to circumvent both natural (immunity) and artificial (drugs, insecticides, vaccines) measures aiming at destroying them; (5) since malaria represents disequilibrium of the system HPM, its control should aim at maintaining or restoring this equilibrium; (6) the disequilibrium of integrated systems involves the disequilibrium of their components, therefore the maintenance or restoration of the system's equilibrium depend on the adoption of integrated and coordinated measures acting on all components, that means, panadaptive
Newton, C.; Hien, T. T.; White, N.
Cerebral malaria may be the most common non-traumatic encephalopathy in the world. The pathogenesis is heterogenous and the neurological complications are often part of a multisystem dysfunction. The clinical presentation and pathophysiology differs between adults and children. Recent studies have elucidated the molecular mechanisms of pathogenesis and raised possible interventions. Antimalarial drugs, however, remain the only intervention that unequivocally affects outcome, although increasing resistance to the established antimalarial drugs is of grave concern. Artemisinin derivatives have made an impact on treatment, but other drugs may be required. With appropriate antimalarial drugs, the prognosis of cerebral malaria often depends on the management of other complications—for example, renal failure and acidosis. Neurological sequelae are increasingly recognised, but further research on the pathogenesis of coma and neurological damage is required to develop other ancillary treatments. PMID:10990500
Price, Ric N; Tjitra, Emiliana; Guerra, Carlos A; Yeung, Shunmay; White, Nicholas J; Anstey, Nicholas M
Plasmodium vivax threatens almost 40% of the world’s population, resulting in 132 - 391 million clinical infections each year. Most of these cases originate from South East Asia and the Western Pacific, although a significant number also occur in Africa and South America. Although often regarded as causing a benign and self-limiting infection, there is increasing evidence that the overall burden, economic impact and severity of disease from P. vivax have been underestimated. Malaria control strategies have had limited success and are confounded by the lack of access to reliable diagnosis, emergence of multidrug resistant isolates and the parasite’s ability to transmit early in the course of disease and relapse from dormant liver stages at varying time intervals after the initial infection. Progress in reducing the burden of disease will require improved access to reliable diagnosis and effective treatment of both blood-stage and latent parasites, and more detailed characterization of the epidemiology, morbidity and economic impact of vivax malaria. Without these, vivax malaria will continue to be neglected by ministries of health, policy makers, researchers and funding bodies. PMID:18165478
Ouattara, Amed; Barry, Alyssa E; Dutta, Sheetij; Remarque, Edmond J; Beeson, James G; Plowe, Christopher V
Prospects for malaria eradication will be greatly enhanced by an effective vaccine, but parasite genetic diversity poses a major impediment to malaria vaccine efficacy. In recent pre-clinical and field trials, vaccines based on polymorphic Plasmodium falciparum antigens have shown efficacy only against homologous strains, raising the specter of allele-specific immunity such as that which plagues vaccines against influenza and HIV. The most advanced malaria vaccine, RTS,S, targets relatively conserved epitopes on the P. falciparum circumsporozoite protein. After more than 40 years of development and testing, RTS,S, has shown significant but modest efficacy against clinical malaria in phase 2 and 3 trials. Ongoing phase 2 studies of an irradiated sporozoite vaccine will ascertain whether the full protection against homologous experimental malaria challenge conferred by high doses of a whole organism vaccine can provide protection against diverse strains in the field. Here we review and evaluate approaches being taken to design broadly cross-protective malaria vaccines.
Poh-Ai Cheong, Irene; Treagust, David; Kyeleve, Iorhemen J.; Oh, Peck-Yoke
In this study, a two-tier diagnostic test for understanding malaria was developed and administered to 314 Bruneian students in Year 12 and in a nursing diploma course. The validity, reliability, difficulty level, discriminant indices, and reading ability of the test were examined and found to be acceptable in terms of measuring students' understanding and identifying alternative conceptions with respect to malaria. Results showed that students' understanding of malaria was high for content, low for reasons, and limited and superficial for both content and reasons. The instrument revealed several common alternative conceptual understandings students' hold about malaria. The MalariaTT2 instrument developed could be used in classroom lessons for challenging alternative conceptions and enhancing conceptions of malaria.
Valecha, Neena; Mohanty, Suman; Srivastava, Prakriti; Sharma, Surya; Tyagi, Prajesh; Bergqvist, Yngve; Ringwald, Pascal
This study was conducted to correlate blood concentrations of lumefantrine with treatment outcome for patients with Plasmodium falciparum malaria when the drug was given without specific instructions for administration with food. Patients with P. falciparum malaria in the highly endemic state of Orissa, India, were enrolled during 2008 and followed-up for 28 days after admistration of artemether-lumefantrine for three days according to a World Health Organization protocol. Drug concentration in whole blood was determined by using blood spots placed on filter paper on day 7. The technology is suitable for field studies. One hundred percent of the patients had an adequate clinical and parasitological response. These results confirm the efficacy of artemether-lumefantrine in persons from poor tribal communities when given without specific instructions regarding co-administration with food, despite high inter-individual variability in blood concentrations of lumefantrine.
Heck, Jonathan F.
Reports a study that examined the incidence of spearing between two high school football seasons, one before and one after a rule change banning spearing. Reviews of 18 game films of a New Jersey team from 1975 and 1990 indicated that, overall, the rule change did not have a favorable impact on the incidence of spearing. (SM)
To adequately assess the effects of global warming it is necessary to address trends and impacts at the local level. This study examines phenological changes in the start-of-season (SOS) derived from satellite observations from 1982–2008 in the US High Plains region. The surface climate-based SOS wa...
Accurately measuring the immune repertoire sequence composition, diversity, and abundance is important in studying repertoire response in infections, vaccinations, and cancer immunology. Using molecular identifiers (MIDs) to tag mRNA molecules is an effective method in improving the accuracy of immune repertoire sequencing (IR-seq). However, it is still difficult to use IR-seq on small amount of clinical samples to achieve a high coverage of the repertoire diversities. This is especially challenging in studying infections and vaccinations where B cell subpopulations with fewer cells, such as memory B cells or plasmablasts, are often of great interest to study somatic mutation patterns and diversity changes. Here, we describe an approach of IR-seq based on the use of MIDs in combination with a clustering method that can reveal more than 80% of the antibody diversity in a sample and can be applied to as few as 1,000 B cells. We applied this to study the antibody repertoires of young children before and during an acute malaria infection. We discovered unexpectedly high levels of somatic hypermutation (SHM) in infants and revealed characteristics of antibody repertoire development in young children that would have a profound impact on immunization in children.
Kirchgeorg, T; Dreyer, A; Gabrielli, P; Gabrieli, J; Thompson, L G; Barbante, C; Ebinghaus, R
The seasonal accumulations of perfluorinated substances (PFAS), polybrominated diphenyl ethers (PBDE) and polycyclic aromatic hydrocarbons (PAH) were measured in a 10 m shallow firn core from a high altitude glacier at Mt. Ortles (Italy, 3830 m above sea level) in South Tyrol in the Italian Eastern Alps. The most abundant persistent organic pollutants of each group were perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) (for PFASs); BDE 47, BDE 99, BDE 209 (for PBDEs) and phenanthrene (PHE), fluoranthene (FLA) and pyrene (PYR) (for PAHs). All compounds show different extents of seasonality, with higher accumulation during summer time compared to winter. This seasonal difference mainly reflects meteorological conditions with a low and stable atmospheric boundary layer in winter and strong convective activity in summer, transformation processes during the transport of chemicals and/or post-depositional alterations. Change in the composition of the water-soluble PFCAs demonstrates the influence of meltwater percolation through the firn layers.
Kiang, Richard K.; Adimi, Farida; Kempler, Steven
This poster presentation reviews the use of NASA remote sensing data that can be used to extract environmental information for modeling malaria transmission. The authors discuss the remote sensing data from Landsat, Advanced Very High Resolution Radiometer (AVHRR), Moderate Resolution Imaging Spectroradiometer (MODIS), Tropical Rainfall Measuring Mission (TRMM), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Earth Observing One (EO-1), Advanced Land Imager (ALI) and Seasonal to Interannual Earth Science Information Partner (SIESIP) dataset.
Francischetti, Ivo M. B.; Seydel, Karl B.; Monteiro, Robson Q.
I. ABSTRACT Malaria remains a highly prevalent disease in more than 90 countries and accounts for at least 1 million deaths every year. Plasmodium falciparum infection is often associated with a procoagulant tonus characterized by thrombocytopenia and activation of the coagulation cascade and fibrinolytic system; however, bleeding and hemorrhage are uncommon events, suggesting that a compensated state of blood coagulation activation occurs in malaria. This article i) reviews the literature related to blood coagulation and malaria in a historic perspective, ii) describes basic mechanisms of coagulation, anticoagulation, and fibrinolysis, iii) explains the laboratory changes in acute and compensated disseminated intravascular coagulation (DIC), iv) discusses the implications of tissue factor (TF) expression in the endothelium of P. falciparum-infected patients, and v) emphasizes the pro-coagulant role of parasitized erythrocytes (pRBC) and activated platelets in the pathogenesis of malaria. This article also presents the ‘Tissue Factor Model’ (TFM) for malaria pathogenesis, which places TF as the interface between sequestration, endothelial cell activation, blood coagulation disorder and inflammation often associated with the disease. The relevance of the coagulation-inflammation cycle for the multiorgan dysfunction and coma is discussed in the context of malaria pathogenesis. PMID:18260002
Hirako, Isabella C.; Gallego-Marin, Carolina; Ataide, Marco A.; Andrade, Warrison A.; Gravina, Humberto; Rocha, Bruno C.; de Oliveira, Rosane B.; Pereira, Dhelio B.; Vinetz, Joseph; Diamond, Betty; Ram, Sanjay; Golenbock, Douglas T.
ABSTRACT High levels of circulating immunocomplexes (ICs) are found in patients with either infectious or sterile inflammation. We report that patients with either Plasmodium falciparum or Plasmodium vivax malaria have increased levels of circulating anti-DNA antibodies and ICs containing parasite DNA. Upon stimulation with malaria-induced ICs, monocytes express an NF-κB transcriptional signature. The main source of IC-induced proinflammatory cytokines (i.e., tumor necrosis factor alpha [TNF-α] and interleukin-1β [IL-1β])in peripheral blood mononuclear cells from acute malaria patients was found to be a CD14+ CD16 (FcγRIIIA)+ CD64 (FcγRI)high CD32 (FcγRIIB)low monocyte subset. Monocytes from convalescent patients were predominantly of the classical phenotype (CD14+ CD16−) that produces high levels of IL-10 and lower levels of TNF-α and IL-1β in response to ICs. Finally, we report a novel role for the proinflammatory activity of ICs by demonstrating their ability to induce inflammasome assembly and caspase-1 activation in human monocytes. These findings illuminate our understanding of the pathogenic role of ICs and monocyte subsets and may be relevant for future development of immunity-based interventions with broad applications to systemic inflammatory diseases. PMID:26578679
Malaria is a disease directly linked to temperature and rainfall. In Ethiopia, the influence of climate variables on malaria transmission and the subsequent role of ENSO in the rise of malaria incidence are becoming more recognized. Numerous publications attest to the extreme sensitivity of malaria to climate in Ethiopia. The majority of large-scale epidemics in the past were associated with climatic factors such as temperature and rainfall. However, there is limited information on climate variability and ENSO at the district level to aid in public health decision-making. Since 2008, the National Meteorogy Agency (NMA) and the International Research Institute for Climate and Society (IRI) have been collaborating on improving climate services in Ethiopia. This collaboration spurred the implementation of the Enhancing National Climate Services (ENACTS) initiative and the creation of the IRI Data Library (DL) NMA Ethiopia Maproom. ENACTS provides reliable and readily accessible climate data at high resolutions and the Maproom uses ENACTS to build a collection of maps and other figures that monitor climate and societal conditions at present and in the recent past (1981-2010). A recent analysis exploring the relationship of rainfall and temperature ENACTS products to malaria epidemics in proceeding rainy seasons within 12 woredas found above normal temperature anomalies to be more readily associated with epidemics when compared to above normal rainfall anomalies, regardless of the ENSO phase (Figure 1-2).
Hira, P R; Al-Ali, F; Soriano, E B; Behbehani, K
There is no indigenous mosquito-borne transmission of malaria in Kuwait. However, in a five year period at a district general hospital, the number of laboratory-diagnosed cases of malaria increased annually from 25 to 84, a rise of 336%. Except for two induced infections, all were imported, mainly from the Indian subcontinent. Plasmodium vivax was responsible for 87.29% of the cases; P.falciparum (12.05%), a mixed infection of P.vivax and P.falciparum (0.33%) and a case of P.ovale (0.33%) were also identified. Rapid preparation of acetone-fixed, Giemsa-stained thick blood films, a heightened awareness of the infection, examination of multiple samples of blood from patients and the general resurgence of malaria in endemic areas were some of the factors responsible for the high number of cases diagnosed. Most patients were young males and presented with clinical malaria due to P.vivax between May and October each year, an apparent seasonal peak. However, many were already resident in the country for a variable period. Patients with P.falciparum though, presented clinically within two weeks of arrival in the country. Parasite densities were calculated to monitor the progress of treatment and identify quickly any possible chloroquine-resistant P.falciparum strains. A policy of active prophylaxis is suggested to stem the tide of imported malaria.
Schubert, Brian A.; Jahren, A. Hope
High-resolution natural abundance stable carbon isotope analyses across annual growth rings in evergreen trees reveal a cyclic increase and decrease in the measured carbon isotopic composition (δ 13C), but the causes of this pattern are poorly understood. We compiled new and published high-resolution δ 13C data from across annual growth rings of 33 modern evergreen trees from 10 genera and 15 globally distributed sites to quantify the parameters that affect the observed δ 13C pattern. Across a broad range of latitude, temperature, and precipitation regimes, we found that the average, measured seasonal change in δ 13C (Δδ 13C meas, ‰) within tree rings of evergreen species reflects changes in the carbon isotopic composition of atmospheric carbon dioxide (Δδ 13C CO2) and changes in seasonal precipitation (Δ P) according to the following equation: Δδ 13C meas = Δδ 13C CO2 - 0.82(Δ P) + 0.73; R2 = 0.96. Seasonal changes in temperature, pCO 2, and light levels were not found to significantly affect Δδ 13C meas. We propose that this relationship can be used to quantify seasonal patterns in paleoprecipitation from intra-ring profiles of δ 13C measured from non-permineralized, fossil wood.
Takem, Ebako Ndip; D’Alessandro, Umberto
Pregnant women have a higher risk of malaria compared to non-pregnant women. This review provides an update on knowledge acquired since 2000 on P. falciparum and P.vivax infections in pregnancy. Maternal risk factors for malaria in pregnancy (MiP) include low maternal age, low parity, and low gestational age. The main effects of MIP include maternal anaemia, low birth weight (LBW), preterm delivery and increased infant and maternal mortality. P. falciparum infected erythrocytes sequester in the placenta by expressing surface antigens, mainly variant surface antigen (VAR2CSA), that bind to specific receptors, mainly chondroitin sulphate A. In stable transmission settings, the higher malaria risk in primigravidae can be explained by the non-recognition of these surface antigens by the immune system. Recently, placental sequestration has been described also for P.vivax infections. The mechanism of preterm delivery and intrauterine growth retardation is not completely understood, but fever (preterm delivery), anaemia, and high cytokines levels have been implicated. Clinical suspicion of MiP should be confirmed by parasitological diagnosis. The sensitivity of microscopy, with placenta histology as the gold standard, is 60% and 45% for peripheral and placental falciparum infections in African women, respectively. Compared to microscopy, RDTs have a lower sensitivity though when the quality of microscopy is low RDTs may be more reliable. Insecticide treated nets (ITN) and intermittent preventive treatment in pregnancy (IPTp) are recommended for the prevention of MiP in stable transmission settings. ITNs have been shown to reduce malaria infection and adverse pregnancy outcomes by 28–47%. Although resistance is a concern, SP has been shown to be equivalent to MQ and AQ for IPTp. For the treatment of uncomplicated malaria during the first trimester, quinine plus clindamycin for 7 days is the first line treatment and artesunate plus clindamycin for 7 days is indicated if
Yhdego, M.; Majura, P. )
A review of the malaria control programs and the problem encountered in the United Republic of Tanzania since 1945 to the year 1986 is discussed. Buguruni, one of the squatter areas in the city of Dar es Salaam, is chosen as a case study in order to evaluate the economic advantage of engineering methods for the control of malaria infection. Although the initial capital cost of engineering methods may be high, the cost effectiveness requires a much lower financial burden of only about Tshs. 3 million compared with the conventional methods of larviciding and insecticiding which requires more than Tshs. 10 million. Finally, recommendations for the adoption of engineering methods are made concerning the upgrading of existing roads and footpaths in general with particular emphasis on drainage of large pools of water which serve as breeding sites for mosquitoes.
Gentilini, M; Caumes, E; Danis, M
The prevention of malaria is based on chemoprophylaxis and protection against the vector. Nocturnal mosquito bites can be avoided by individual and collective measures, while chemoprophylaxis involves the use of various agents according to the place and duration of stay. Three endemic zones can be defined on the basis of chemoresistance. Chloroquine, proguanil and mefloquine are the three drugs used in this setting, the latter being contraindicated for pregnant women and children. Travellers making long stays in areas of low-level chemoresistance and short stays in areas of high-level resistance and for whom mefloquine is contraindicated are advised to take antimalarial drugs at the first signs of potentially malarial fever when medical care is unavailable. Quinine, halofantrine and mefloquine are used for the curative treatment of malaria in areas of chloroquine resistance.
Casals-Pascual, Climent; Idro, Richard; Gicheru, Nimmo; Gwer, Samson; Kitsao, Barnes; Gitau, Evelyn; Mwakesi, Robert; Roberts, David J.; Newton, Charles R. J. C.
Cerebral malaria (CM) in children is associated with a high mortality and long-term neurocognitive sequelae. Both erythropoietin (Epo) and vascular endothelial growth factor (VEGF) have been shown to be neuroprotective. We hypothesized that high plasma and cerebrospinal fluid (CSF) levels of these cytokines would prevent neurological sequelae in children with CM. We measured Epo, VEGF, and tumor necrosis factor in paired samples of plasma and CSF of Kenyan children admitted with CM. Logistic regression models were used to identify risk and protective factors associated with the development of neurological sequelae. Children with CM (n = 124) were categorized into three groups: 76 without sequelae, 32 with sequelae, and 16 who died. Conditional logistic regression analysis matching the 32 patients with CM and neurological sequelae to 64 patients with CM without sequelae stratified for hemoglobin level estimated that plasma Epo (>200 units/liter) was associated with >80% reduction in the risk of developing neurological sequelae [adjusted odds ratio (OR) 0.18; 95% C.I. 0.05–0.93; P = 0.041]. Admission with profound coma (adjusted OR 5.47; 95% C.I. 1.45–20.67; P = 0.012) and convulsions after admission (adjusted OR 16.35; 95% C.I. 2.94–90.79; P = 0.001) were also independently associated with neurological sequelae. High levels of Epo were associated with reduced risk of neurological sequelae in children with CM. The age-dependent Epo response to anemia and the age-dependent protective effect may influence the clinical epidemiology of CM. These data support further study of Epo as an adjuvant therapy in CM. PMID:18263734
Egge, Elianne Sirnæs; Johannessen, Torill Vik; Andersen, Tom; Eikrem, Wenche; Bittner, Lucie; Larsen, Aud; Sandaa, Ruth-Anne; Edvardsen, Bente
Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance at the species level is limited due to their small cell size and few morphological features visible under the light microscope. Here, we present unique data on haptophyte seasonal diversity and dynamics from two annual cycles, with the taxonomic resolution and sampling depth obtained with high-throughput sequencing. From outer Oslofjorden, S Norway, nano- and picoplanktonic samples were collected monthly for 2 years, and the haptophytes targeted by amplification of RNA/cDNA with Haptophyta-specific 18S rDNA V4 primers. We obtained 156 operational taxonomic units (OTUs), from c. 400.000 454 pyrosequencing reads, after rigorous bioinformatic filtering and clustering at 99.5%. Most OTUs represented uncultured and/or not yet 18S rDNA-sequenced species. Haptophyte OTU richness and community composition exhibited high temporal variation and significant yearly periodicity. Richness was highest in September–October (autumn) and lowest in April–May (spring). Some taxa were detected all year, such as Chrysochromulina simplex, Emiliania huxleyi and Phaeocystis cordata, whereas most calcifying coccolithophores only appeared from summer to early winter. We also revealed the seasonal dynamics of OTUs representing putative novel classes (clades HAP-3–5) or orders (clades D, E, F). Season, light and temperature accounted for 29% of the variation in OTU composition. Residual variation may be related to biotic factors, such as competition and viral infection. This study provides new, in-depth knowledge on seasonal diversity and dynamics of haptophytes in North Atlantic coastal waters. PMID:25893259
Tan, Kathrine R.; Magill, Alan J.; Parise, Monica E.; Arguin, Paul M.
Doxycycline, a synthetically derived tetracycline, is a partially efficacious causal prophylactic (liver stage of Plasmodium) drug and a slow acting blood schizontocidal agent highly effective for the prevention of malaria. When used in conjunction with a fast acting schizontocidal agent, it is also highly effective for malaria treatment. Doxycycline is especially useful as a prophylaxis in areas with chloroquine and multidrug-resistant Plasmodium falciparum malaria. Although not recommended for pregnant women and children < 8 years of age, severe adverse events are rarely reported for doxycycline. This report examines the evidence behind current recommendations for the use of doxycycline for malaria and summarizes the available literature on its safety and tolerability. PMID:21460003
Beck, H P; Felger, I; Genton, B; Alexander, N; al-Yaman, F; Anders, R F; Alpers, M
A parasitological and immunological survey was carried out in an area in Papua New Guinea highly endemic for malaria. Two hundred fourteen adult individuals were selected for studies to assess their immune responses against the malaria vaccine candidate ring-infected erythrocyte surface antigen (RESA). Total immunoglobulin G (IgG) antibodies directed against RESA as well as specific IgG1, IgG2, and IgG3 antibodies were determined. Humoral responses directed against RESA were frequent in all IgG subclasses. Only IgG3 responses were found to be age dependent. Total anti-RESA IgG antibodies were not correlated with protection against malaria as measured by parasite prevalence, parasite density, or health center attendance. In contrast, cytophilic antibodies (IgG1 and IgG3) were associated with reduced Plasmodium falciparum prevalence and reduced health center attendance. T-cell proliferation in general was low and very infrequent. No correlation between humoral and cellular immune responses could be found. Parasite density, parasite prevalence, and health center visits tended to be reduced in individuals with good humoral and cell-mediated immune responses. PMID:7822028
Kouriba, Bourema; Bergmann-Leitner, Elke; Angov, Evelina; Coulibaly, Drissa; Diarra, Issa; Daou, Modibo; Niangaly, Amadou; Blackwelder, William C.; Wu, Yukun; Cohen, Joe; Ballou, W. Ripley; Vekemans, Johan; Lanar, David E.; Dutta, Sheetij; Diggs, Carter; Soisson, Lorraine; Heppner, D. Gray; Doumbo, Ogobara K.; Plowe, Christopher V.; Thera, Mahamadou A.
The blood-stage malaria vaccine FMP2.1/AS02A, comprised of recombinant Plasmodium falciparum apical membrane antigen 1 (AMA1) and the adjuvant system AS02A, had strain-specific efficacy against clinical malaria caused by P. falciparum with the vaccine strain 3D7 AMA1 sequence. To evaluate a potential correlate of protection, we measured the ability of participant sera to inhibit growth of 3D7 and FVO strains in vitro using high-throughput growth inhibition assay (GIA) testing. Sera from 400 children randomized to receive either malaria vaccine or a control rabies vaccine were assessed at baseline and over two annual malaria transmission seasons after immunization. Baseline GIA against vaccine strain 3D7 and FVO strain was similar in both groups, but more children in the malaria vaccine group than in the control group had 3D7 and FVO GIA activity ≥15% 30 days after the last vaccination (day 90) (49% vs. 16%, p<0.0001; and 71.8% vs. 60.4%, p = 0.02). From baseline to day 90, 3D7 GIA in the vaccine group was 7.4 times the mean increase in the control group (p<0.0001). In AMA1 vaccinees, 3D7 GIA activity subsequently returned to baseline one year after vaccination (day 364) and did not correlate with efficacy in the extended efficacy time period to day 730. In Cox proportional hazards regression models with time-varying covariates, there was a slight suggestion of an association between 3D7 GIA activity and increased risk of clinical malaria between day 90 and day 240. We conclude that vaccination with this AMA1-based malaria vaccine increased inhibition of parasite growth, but this increase was not associated with allele-specific efficacy in the first malaria season. These results provide a framework for testing functional immune correlates of protection against clinical malaria in field trials, and will help to guide similar analyses for next-generation malaria vaccines. Clinical trials registry: This clinical trial was registered on clinicaltrials.gov, registry
Mountain Gem Russet is a medium to late maturing variety with both high early and full season yields of oblong-long, medium-russeted tubers having higher protein content than those of standard potato varieties. Mountain Gem Russet has greater resistance to tuber late blight, tuber malformations and ...
Wort, Ulrika Uddenfeldt; Hastings, Ian; Mutabingwa, TK; Brabin, Bernard J
Background The impact of malaria on the risk of stillbirth is still under debate. The aim of the present analysis was to determine comparative changes in stillbirth prevalence between two areas of Tanzania with different malaria transmission patterns in order to estimate the malaria attributable component. Methods A retrospective analysis was completed of stillbirth differences between primigravidae and multigravidae in relation to malaria cases and transmission patterns for two different areas of Tanzania with a focus on the effects of the El Niño southern climatic oscillation (ENSO). One area, Kagera, experiences outbreaks of malaria, and the other area, Morogoro, is holoendemic. Delivery and malaria data were collected over a six year period from records of the two district hospitals in these locations. Results There was a significantly higher prevalence of low birthweight in primigravidae compared to multigravidae for both data sets. Low birthweight and stillbirth prevalence (17.5% and 4.8%) were significantly higher in Kilosa compared to Ndolage (11.9% and 2.4%). There was a significant difference in stillbirth prevalence between Ndolage and Kilosa between malaria seasons (2.4% and 5.6% respectively, p < 0.001) and during malaria seasons (1.9% and 5.9% respectively, p < 0.001). During ENSO there was no difference (4.1% and 4.9%, respectively). There was a significant difference in low birthweight prevalence between Ndolage and Kilosa between malaria seasons (14.4% and 23.0% respectively, p < 0.001) and in relation to malaria seasons (13.9% and 25.2% respectively, p < 0.001). During ENSO there was no difference (22.2% and 19.8%, respectively). Increased low birthweight risk occurred approximately five months following peak malaria prevalence, but stillbirth risk increased at the time of malaria peaks. Conclusion Malaria exposure during pregnancy has a delayed effect on birthweight outcomes, but a more acute effect on stillbirth risk. PMID:17044915
Allen, Michael J.; Lee, Cameron C.
Due to a number of complicating factors, cold-related mortality has long been understudied. Through a synoptic climatological, environment-to-circulation perspective, this research takes a unique approach in examining anomalous surface temperature and pressure map patterns associated with the days leading up to high-mortality, spike days for Chicago, Illinois during the cold season. Atmospheric conditions leading to spike days during the cold season were evaluated through both seasonal anomaly and 1-day anomaly maps. Results indicate that high-mortality days are typically preceded by unseasonably cold weather situated over the region from 2 to 5 days beforehand, with significantly higher than average pressure 1 to 2 days before a mortality spike. As this system moves eastward, a significant 1-day warming trend accompanying a significant drop in sea level pressure follows—occurring on the day of the mortality spike or 1 day prior. Both scenarios—cold, high pressure air exposure and the rapid change in weather—are consistent with previous literature connecting them as factors contributing to cold-related mortality increases, with this sequence possibly playing a key role in yielding mortality levels anomalous enough to meet the threshold for a spike.
Sparks, J. J.; Janches, D.; Nicolls, M. J.; Heinselman, C. J.
We report in this and a companion paper [Fentzke, J.T., Janches, D., Sparks, J.J., 2008. Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.07.015] a complete seasonal study of the micrometeor input function (MIF) at high latitudes using meteor head-echo radar observations performed with the Poker Flat Incoherent Scatter Radar (PFISR). This flux is responsible for a number of atmospheric phenomena; for example, it could be the source of meteoric smoke that is thought to act as condensation nuclei in the formation of ice particles in the polar mesosphere. The observations presented here were performed for full 24-h periods near the summer and winter solstices and spring and autumn equinoxes, times at which the seasonal variability of the MIF is predicted to be large at high latitudes [Janches, D., Heinselman, C.J., Chau, J.L., Chandran, A., Woodman, R., 2006. Modeling of the micrometeor input function in the upper atmosphere observed by High Power and Large Aperture Radars, JGR, 11, A07317, doi:10.1029/2006JA011628]. Precise altitude and radar instantaneous line-of-sight (radial) Doppler velocity information are obtained for each of the hundreds of events detected every day. We show that meteor rates, altitude, and radial velocity distributions have a large seasonal dependence. This seasonal variability can be explained by a change in the relative location of the meteoroid sources with respect to the observer. Our results show that the meteor flux into the upper atmosphere is strongly anisotropic and its characteristics must be accounted for when including this flux into models attempting to explain related aeronomical phenomena. In addition, the measured acceleration and received signal strength distribution do not seem to depend on season; which may suggest that these observed
Malaria prevention in travelers to endemic areas remains dependent principally on chemoprophylaxis. Although malaria chemoprophylaxis refers to all malaria species, a distinction should be drawn between falciparum malaria prophylaxis and the prophylaxis of the relapsing malaria species (vivax & ovale). While the emergence of drug resistant strains, as well as the costs and adverse reactions to medications, complicate falciparum prophylaxis use, there are virtually no drugs available for vivax prophylaxis, beside of primaquine. Based on traveler’s malaria data, a revised recommendation for using chemoprophylaxis in low risk areas should be considered. PMID:22811794
Pierce, Susan K; Miller, Louis H
Malaria kills >1 million children each year, and there is little doubt that an effective vaccine would play a central role in preventing these deaths. However, the strategies that proved so successful in developing the vaccines we have today may simply not be adequate to confront complex, persistent infectious diseases, including malaria, AIDS, and tuberculosis. We believe that the development of a highly effective vaccine will require a better understanding of several features of the immune response to malaria. At the top of the list is the complex and ancient relationship between the parasite that causes malaria and the immune system that enables the parasite to persist in an otherwise functional immune system. A close second is the antigenic targets in malaria and how to overcome the enormous polymorphism of these targets. Meeting these challenges represents a call to arms of basic immunologists to advance our knowledge of malaria immunity.
van der Kaay, H. J.; Klein, F.; Hagenaar—de Weerdt, M.; Meuwissen, J. H. E. T.
An investigation of malariometric indices in relation to immunoglobulin levels, rheumatoid factors, and antithyroglobulins was carried out on 78 members of the Arfak tribe near Manokwari in Western New Guinea, in the course of a WHO assessment of malaria control activities in that region. The population investigated had been exposed to a period of epidemic malaria, as indicated by the small differences in malariometric indices between consecutive age groups. Typically high spleen sizes were recorded, as found generally among Papuans in similar situations. Falciparum malaria was most prevalent, almost equal to cases of vivax and malariae malaria together. IgM levels were very high, while those of IgG, IgA and IgD were not elevated. Total serum protein was rather low. No correlation between malariometric indices, autoantibodies, and immunoglobulin levels could be found. In particular there was no correlation between IgM levels and spleen indices, such as has been found in many other surveys. It is suggested that splenomegaly may show no correlation with the IgM level in Papuan populations without previous selection. PMID:4211055
Glaizot, Olivier; Fumagalli, Luca; Iritano, Katia; Lalubin, Fabrice; Van Rooyen, Juan; Christe, Philippe
Avian malaria studies have taken a prominent place in different aspects of evolutionary ecology. Despite a recent interest in the role of vectors within the complex interaction system of the malaria parasite, they have largely been ignored in most epidemiological studies. Epidemiology of the disease is however strongly related to the vector's ecology and behaviour, and there is a need for basic investigations to obtain a better picture of the natural associations between Plasmodium lineages, vector species and bird hosts. The aim of the present study was to identify the mosquito species involved in the transmission of the haemosporidian parasites Plasmodium spp. in two wild populations of breeding great tits (Parus major) in western Switzerland. Additionally, we compared Plasmodium lineages, based on mitochondrial DNA cytochrome b sequences, between the vertebrate and dipteran hosts, and evaluated the prevalence of the parasite in the mosquito populations. Plasmodium spp. were detected in Culex pipiens only, with an overall 6.6% prevalence. Among the six cytochrome b lineages of Plasmodium identified in the mosquitoes, three were also present in great tits. The results provide evidence for the first time that C. pipiens can act as a natural vector of avian malaria in Europe and yield baseline data for future research on the epidemiology of avian malaria in European countries. PMID:22506060
Glaizot, Olivier; Fumagalli, Luca; Iritano, Katia; Lalubin, Fabrice; Van Rooyen, Juan; Christe, Philippe
Avian malaria studies have taken a prominent place in different aspects of evolutionary ecology. Despite a recent interest in the role of vectors within the complex interaction system of the malaria parasite, they have largely been ignored in most epidemiological studies. Epidemiology of the disease is however strongly related to the vector's ecology and behaviour, and there is a need for basic investigations to obtain a better picture of the natural associations between Plasmodium lineages, vector species and bird hosts. The aim of the present study was to identify the mosquito species involved in the transmission of the haemosporidian parasites Plasmodium spp. in two wild populations of breeding great tits (Parus major) in western Switzerland. Additionally, we compared Plasmodium lineages, based on mitochondrial DNA cytochrome b sequences, between the vertebrate and dipteran hosts, and evaluated the prevalence of the parasite in the mosquito populations. Plasmodium spp. were detected in Culex pipiens only, with an overall 6.6% prevalence. Among the six cytochrome b lineages of Plasmodium identified in the mosquitoes, three were also present in great tits. The results provide evidence for the first time that C. pipiens can act as a natural vector of avian malaria in Europe and yield baseline data for future research on the epidemiology of avian malaria in European countries.
Yatsushiro, Shouki; Yamamoto, Takeki; Yamamura, Shohei; Abe, Kaori; Obana, Eriko; Nogami, Takahiro; Hayashi, Takuya; Sesei, Takashi; Oka, Hiroaki; Okello-Onen, Joseph; Odongo-Aginya, Emmanuel I.; Alai, Mary Auma; Olia, Alex; Anywar, Dennis; Sakurai, Miki; Palacpac, Nirianne MQ; Mita, Toshihiro; Horii, Toshihiro; Baba, Yoshinobu; Kataoka, Masatoshi
Accurate, sensitive, rapid, and easy operative diagnosis is necessary to prevent the spread of malaria. A cell microarray chip system including a push column for the recovery of erythrocytes and a fluorescence detector was employed for malaria diagnosis in Uganda. The chip with 20,944 microchambers (105 μm width and 50 μm depth) was made of polystyrene. For the analysis, 6 μl of whole blood was employed, and leukocytes were practically removed by filtration through SiO2-nano-fibers in a column. Regular formation of an erythrocyte monolayer in each microchamber was observed following dispersion of an erythrocyte suspension in a nuclear staining dye, SYTO 21, onto the chip surface and washing. About 500,000 erythrocytes were analyzed in a total of 4675 microchambers, and malaria parasite-infected erythrocytes could be detected in 5 min by using the fluorescence detector. The percentage of infected erythrocytes in each of 41 patients was determined. Accurate and quantitative detection of the parasites could be performed. A good correlation between examinations via optical microscopy and by our chip system was demonstrated over the parasitemia range of 0.0039–2.3438% by linear regression analysis (R2 = 0.9945). Thus, we showed the potential of this chip system for the diagnosis of malaria. PMID:27445125
Singh, Veer Bahadur; Meena, Babu Lal; Chandra, Subhash; Agrawal, Jatin; Kanogiya, Naresh
manifestations are not an uncommon presentation of malaria. Most commonly caused by PF malaria. Malaria should be thought as a differential diagnosis in pyrexia with neuropsychiatric manifestation. Observation obtained in the study will be highly useful for the diagnosis and management of patients suffering from malaria. PMID:27630883
Pitts, R. Jason; Fox, A. Nicole; Zwiebel, Laurence J.
Anopheles gambiae is a highly anthropophilic mosquito responsible for the majority of malaria transmission in Africa. The biting and host preference behavior of this disease vector is largely influenced by its sense of smell, which is presumably facilitated by G protein-coupled receptor signaling [Takken, W. & Knols, B. (1999) Annu. Rev. Entomol. 44, 131-157]. Because of the importance of host preference to the mosquitoes' ability to transmit disease, we have initiated studies intended to elucidate the molecular mechanisms underlying olfaction in An. gambiae. In the course of these studies, we have identified a number of genes potentially involved in signal transduction, including a family of candidate odorant receptors. One of these receptors, encoded by GPRor7 (hereafter referred to as AgOr7), is remarkably similar to an odorant receptor that is expressed broadly in olfactory tissues and has been identified in Drosophila melanogaster and other insects [Krieger, J., Klink, O., Mohl, C., Raming, K. & Breer, H. (2003) J. Comp. Physiol. A 189, 519-526; Vosshall, L. B., Amrein, H., Morozov, P. S., Rzhetsky, A. & Axel, R. (1999) Cell 96, 725-736]. We have observed AgOr7 expression in olfactory and gustatory tissues in adult An. gambiae and during several stages of the mosquitoes' development. Within the female adult peripheral chemosensory system, antiserum against the AgOR7 polypeptide labels most sensilla of the antenna and maxillary palp as well as a subset of proboscis sensilla. Furthermore, AgOR7 antiserum labeling is observed within the larval antenna and maxillary palpus. These results are consistent with a role for AgOr7 in both olfaction and gustation in An. gambiae and raise the possibility that AgOr7 orthologs may also be of general importance to both modalities of chemosensation in other insects. PMID:15037749
Lalloo, David G; Shingadia, Delane; Bell, David J; Beeching, Nicholas J; Whitty, Christopher J M; Chiodini, Peter L
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
Diop, Abdoulaye; Konate, Lassana; Molez, Jean-François; Diouf, Malick; Gaye, Oumar; Fontenille, Didier; Diagne, Moussa; Faye, Ousmane
This study of malaria biodiversity in Senegal used an entomological approach that combined parasite surveys and clinical investigations in the mangrove area of the Saloum delta from 1996 to 1998. The parasitologic studies took place in two of the six villages in the coastal area of Palmarin (Djifère and Diakhanor) during three distinct periods: at the end of the dry season, in the middle of the rainy season, and at the end of the rainy season. The clinical investigations at the Palmarin health station took place from July 1996 through February 1998. A malaria attack was defined as the presence of malaria symptoms (including fever, headaches, sweating, and shivering) associated with plasmodic parasitemia > 3,000 trophozoites/microL of blood. All the positive thick smears were infected with Plasmodium falciparum, one also with P. falciparum, and none with P. ovale. The average plasmodic index (5.6%) classifies the delta of Saloum as a hypoendemic area. The average parasite load was estimated at 2,239 trophozoites (95% CI: 1,660-3,020) of P. falciparum per microliter of blood, and 86.9% of patients with symptoms of a malaria attack were febrile. Malaria attacks accounted for 1.9% of the total consultations, 12.2% of the presumed malaria cases, and 14.0% of the febrile subjects. The finding that malaria attacks affected all age groups confirms the weakness of anti-malaria immunity among the population of the Saloum delta. Malaria cases were more frequent at the end of the rainy season and the beginning of the dry season, periods when parasite loads were highest. In this area, which is increasingly attractive to tourists and has a quite superficial fresh water table, man-made environmental changes favor mosquito breeding sites that promote the development of An. arabiensis and An. gambiae spp, both known to be major malaria vectors. In view of the population's weak anti-malaria immunity, this situation may increase malaria transmission and could be followed by
Myrvang, B; Godal, T
Malaria is one of the main health problems in the world with 300-500 millions cases yearly and about one million deaths, mainly children in Sub-Saharan Africa. In the 1990s the malaria problem in Africa has increased, although we have methods to control the disease. In 1998 the new secretary general of WHO, Gro Harlem Brundtland, established the Roll Back Malaria programme, with the aim to markedly reduce malaria morbidity and mortality. Governments in malaria-affected countries have to take the lead in Roll Back Malaria. Their health systems must be improved and malaria control integrated into the general health system, and the methods available for prevention and treatment have to be intensified and improved. At the same time, Roll Back Malaria will encourage and promote malaria research which hopefully will result in new medicines, vaccines and other tools which will improve the chances of reducing malaria-related deaths and suffering. Roll Back Malaria is a cabinet project within the WHO, and the organisation has a key role as manager, co-ordinator and monitor of the project. However, it depends for resources on international support and commitment from other UN bodies, the World Bank, governments in the western world, pharmaceutical industry, philanthropists and other sources. At present an optimistic view prevails, and the preliminary aim, to halve the malaria mortality by the year 2010, seems realistic even with the control methods of today. However, if research efforts result in new and better tools to combat the disease, the task will definitely be easier.
Bomblies, Arne; Duchemin, Jean-Bernard; Eltahir, Elfatih AB
Background Malaria transmission models commonly incorporate spatial environmental and climate variability for making regional predictions of disease risk. However, a mismatch of these models' typical spatial resolutions and the characteristic scale of malaria vector population dynamics may confound disease risk predictions in areas of high spatial hydrological variability such as the Sahel region of Africa. Methods Field observations spanning two years from two Niger villages are compared. The two villages are separated by only 30 km but exhibit a ten-fold difference in anopheles mosquito density. These two villages would be covered by a single grid cell in many malaria models, yet their entomological activity differs greatly. Environmental conditions and associated entomological activity are simulated at high spatial- and temporal resolution using a mechanistic approach that couples a distributed hydrology scheme and an entomological model. Model results are compared to regular field observations of Anopheles gambiae sensu lato mosquito populations and local hydrology. The model resolves the formation and persistence of individual pools that facilitate mosquito breeding and predicts spatio-temporal mosquito population variability at high resolution using an agent-based modeling approach. Results Observations of soil moisture, pool size, and pool persistence are reproduced by the model. The resulting breeding of mosquitoes in the simulated pools yields time-integrated seasonal mosquito population dynamics that closely follow observations from captured mosquito abundance. Interannual difference in mosquito abundance is simulated, and the inter-village difference in mosquito population is reproduced for two years of observations. These modeling results emulate the known focal nature of malaria in Niger Sahel villages. Conclusion Hydrological variability must be represented at high spatial and temporal resolution to achieve accurate predictive ability of malaria risk
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.
Alareqi, Lina M Q; Mahdy, Mohammed A K; Lau, Yee-Ling; Fong, Mun-Yik; Abdul-Ghani, Rashad; Mahmud, Rohela
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
Background The communities of Namawala and Idete villages in southern Tanzania experienced extremely high malaria transmission in the 1990s. By 2001-03, following high usage rates (75% of all age groups) of untreated bed nets, a 4.2-fold reduction in malaria transmission intensity was achieved. Since 2006, a national-scale programme has promoted the use of longer-lasting insecticide treatment kits (consisting of an insecticide plus binder) co-packaged with all bed nets manufactured in the country. Methods The entomological inoculation rate (EIR) was estimated through monthly surveys in 72 houses randomly selected in each of the two villages. Mosquitoes were caught using CDC light traps placed beside occupied bed nets between January and December 2008 (n = 1,648 trap nights). Sub-samples of mosquitoes were taken from each trap to determine parity status, sporozoite infection and Anopheles gambiae complex sibling species identity. Results Compared with a historical mean EIR of ~1400 infectious bites/person/year (ib/p/y) in 1990-94; the 2008 estimate of 81 ib/p/y represents an 18-fold reduction for an unprotected person without a net. The combined impact of longer-lasting insecticide treatments as well as high bed net coverage was associated with a 4.6-fold reduction in EIR, on top of the impact from the use of untreated nets alone. The scale-up of bed nets and subsequent insecticidal treatment has reduced the density of the anthropophagic, endophagic primary vector species, Anopheles gambiae sensu stricto, by 79%. In contrast, the reduction in density of the zoophagic, exophagic sibling species Anopheles arabiensis was only 38%. Conclusion Insecticide treatment of nets reduced the intensity of malaria transmission in addition to that achieved by the untreated nets alone. Impacts were most pronounced against the highly anthropophagic, endophagic primary vector, leading to a shift in the sibling species composition of the A. gambiae complex. PMID:20579399
Amangel'diev, K A; Morozova, K V; Medalieva, D O
As a result of comprehensive research on the causative agents and vectors of malaria and wide use of synthetic antimalarials and highly effective residual insecticides, endemic malaria was eliminated in Turkmenistan by 1960. During the period 1965-1980, 23 local cases of malaria were recorded in Turkmenistan. These local cases were confined to the regions of Mary and Akhal, on the borders of neighbouring countries. In 1998 the epidemiological situation in the country worsened and local transmission of infection resumed. During the year the number of cases recorded was 137:134 being a first diagnosis of the disease and three being relapsed cases. In comparison with 1997, the previous year, incidence was up by 123 cases (a 9.7-fold increase), while the incidence of imported cases of malaria went up by 11 (a 2.2-fold increase), principally in Dashkhovuz and Lebar regions, being brought in from malaria foci in Gushgin district, Turkey, Azerbaijan and Tadjikistan. Local transmission of malaria went up by 111 cases (a 27.7 fold increase); 108 cases were recorded in Gushgin district, Mary region. The first case of malaria in Gushkin district was detected in June 1998. At that time there were five active foci. The approximate number of inhabitants in the active focus area was 10,000. The appearance of local malaria in border districts was caused by the periodic influx of infected mosquitos from neighbouring countries (Afghanistan).
Allen, Michael J.; Sheridan, Scott C.
While the relationship between weather and human health has been studied from various perspectives, this study examines an alternative method of analysis by examining weather conditions on specific high-mortality days during the winter season. These high-mortality days, by definition, represent days with dramatic increases in mortality and the days with the highest mortality. By focusing solely on high-mortality days, this research examines the relationship between weather variables and mortality through a synoptic climatology, environment-to circulation approach. The atmospheric conditions during high-mortality days were compared to the days prior and the days not classified as high-mortality days. Similar patterns emerged across all five locations despite the spatial and temporal variability. Southern locations had a stronger relationship with temperature changes while northern locations showed a greater relationship to atmospheric pressure. Overall, all high-mortality days were associated with warmer temperatures, decreased pressure, and a greater likelihood of precipitation when compared to the previous subset of days. While the atmospheric conditions were consistent across all locations, the importance of the lag effect should not be overlooked as a contributing factor to mortality during the winter season. Through a variety of diverse, methodological approaches, future studies may build upon these results and explore in more detail the complex relationship between weather situations and the impact of short-term changes in weather and health outcomes.
... period for malaria is the time between the mosquito bite and the release of parasites from the ... Health authorities try to prevent malaria by using mosquito-control programs aimed at killing mosquitoes that carry ...
... it is passed from person to person (from mother to child in "congenital malaria," or through blood ... risk for malaria. Your doctor can give your family anti-malarial drugs to prevent the disease, which ...
Adlaoui, E; Faraj, C; El Bouhmi, M; El Aboudi, A; Ouahabi, S; Tran, A; Fontenille, D; El Aouad, R
Malaria resurgence risk in Morocco depends, among other factors, on environmental changes as well as the introduction of parasite carriers. The aim of this paper is to analyze the receptivity of the Loukkos area, large wetlands in Northern Morocco, to quantify and to map malaria transmission risk in this region using biological and environmental data. This risk was assessed on entomological risk basis and was mapped using environmental markers derived from satellite imagery. Maps showing spatial and temporal variations of entomological risk for Plasmodium vivax and P. falciparum were produced. Results showed this risk to be highly seasonal and much higher in rice fields than in swamps. This risk is lower for Afrotropical P. falciparum strains because of the low infectivity of Anopheles labranchiae, principal malaria vector in Morocco. However, it is very high for P. vivax mainly during summer corresponding to the rice cultivation period. Although the entomological risk is high in Loukkos region, malaria resurgence risk remains very low, because of the low vulnerability of the area.
Background Malaria is an important threat to travelers visiting endemic regions. The risk of acquiring malaria is complex and a number of factors including transmission intensity, duration of exposure, season of the year and use of chemoprophylaxis have to be taken into account estimating risk. Materials and methods A mathematical model was developed to estimate the risk of non-immune individual acquiring falciparum malaria when traveling to the Amazon region of Brazil. The risk of malaria infection to travelers was calculated as a function of duration of exposure and season of arrival. Results The results suggest significant variation of risk for non-immune travelers depending on arrival season, duration of the visit and transmission intensity. The calculated risk for visitors staying longer than 4 months during peak transmission was 0.5% per visit. Conclusions Risk estimates based on mathematical modeling based on accurate data can be a valuable tool in assessing risk/benefits and cost/benefits when deciding on the value of interventions for travelers to malaria endemic regions. PMID:20015392
Bizimana, Jean Pierre; Kienberger, Stefan; Hagenlocher, Michael; Twarabamenye, Emmanuel
Despite the decline in malaria incidence due to intense interventions, potentials for malaria transmission persist in Rwanda. To eradicate malaria in Rwanda, strategies need to expand beyond approaches that focus solely on malaria epidemiology and also consider the socioeconomic, demographic and biological/disease-related factors that determine the vulnerability of potentially exposed populations. This paper analyses current levels of social vulnerability to malaria in Rwanda by integrating a set of weighted vulnerability indicators. The paper uses regionalisation techniques as a spatially explicit approach for delineating homogeneous regions of social vulnerability to malaria. This overcomes the limitations of administrative boundaries for modelling the trans-boundary social vulnerability to malaria. The utilised approach revealed high levels of social vulnerability to malaria in the highland areas of Rwanda, as well as in remote areas where populations are more susceptible. Susceptibility may be due to the populations' lacking the capacity to anticipate mosquito bites, or lacking resilience to cope with or recover from malaria infection. By highlighting the most influential indicators of social vulnerability to malaria, the applied approach indicates which vulnerability domains need to be addressed, and where appropriate interventions are most required. Interventions to improve the socioeconomic development in highly vulnerable areas could prove highly effective, and provide sustainable outcomes against malaria in Rwanda. This would ultimately increase the resilience of the population and their capacity to better anticipate, cope with, and recover from possible infection.
Trigg, P I; Kondrachine, A V
In May 1955 the Eighth World Health Assembly adopted a Global Malaria Eradication Campaign based on the widespread use of DDT against mosquitos and of antimalarial drugs to treat malaria and to eliminate the parasite in humans. As a result of the Campaign, malaria was eradicated by 1967 from all developed countries where the disease was endemic and large areas of tropical Asia and Latin America were freed from the risk of infection. The Malaria Eradication Campaign was only launched in three countries of tropical Africa since it was not considered feasible in the others. Despite these achievements, improvements in the malaria situation could not be maintained indefinitely by time-limited, highly prescriptive and centralized programmes. Also, vector resistance to DDT and of malaria parasites to chloroquine, a safe and affordable drug, began to affect programme activities. A global Malaria Control Strategy was endorsed by a Ministerial Conference on Malaria Control in 1992 and confirmed by the World Health Assembly in 1993. This strategy differs considerably from the approach used in the eradication era. It is rooted in the primary health care approach and calls for flexible, decentralized programmes, based on disease rather than parasite control, using the rational and selective use of tools to combat malaria. The implementation of the Global Strategy is beginning to have an impact in several countries, such as Brazil, China, Solomon Islands, Philippines, Vanuatu, Viet Nam and Thailand. The lesson from these areas is clear: malaria is being controlled using the tools that are currently available. The challenge is now to apply these tools among vulnerable individuals and groups experiencing high levels of morbidity and mortality, particularly in sub-Saharan Africa, for which long-term investments are required.
Wan, Yongshan; Wan, Lei; Li, Yuncong; Doering, Peter
Understanding anthropogenic and hydro-climatic influences on nutrient concentrations and export from highly managed catchments often necessitates trend detection using long-term monitoring data. This study analyzed the temporal trend (1979-2014) of total nitrogen (TN) and total phosphorus (TP) concentrations and export from four adjacent coastal basins in south Florida where land and water resources are highly managed through an intricate canal network. The method of integrated seasonal-trend decomposition using LOESS (LOcally weighted regrESSion) was employed for trend detection. The results indicated that long-term trends in TN and TP concentrations (increasing/decreasing) varied with basins and nutrient species, reflecting the influence of basin specific land and water management practices. These long-term trends were intervened by short-term highs driven by high rainfall and discharges and lows associated with regional droughts. Seasonal variations in TP were more apparent than for TN. Nutrient export exhibited a chemostatic behavior for TN from all the basins, largely due to the biogenic nature of organic N associated with the ubiquity of organic materials in the managed canal network. Varying degrees of chemodynamic export was present for TP, reflecting complex biogeochemical responses to the legacy of long-term fertilization, low soil P holding capacity, and intensive stormwater management. The anthropogenic and hydro-climatic influences on nutrient concentration and export behavior had great implications in nutrient loading abatement strategies for aquatic ecosystem restoration of the downstream receiving waterbody.
In October 1998, World Health Organization Director-General Gro Harlem Brundtland announced Roll Back Malaria, a multiagency crusade that aims to cut malaria mortality in half over the next 10 years. Brundtland might just be the one to pull it off, say numerous public health experts, although some researchers question whether the goal is realistic.
Hatz, F R; Beck, B; Blum, J; Funk, M; Furrer, H; Genton, B; Holzer, B; Loutan, L; Markwalder, K; Raeber, P A; Schlagenhauf, P; Siegl, G; Steffen, R; Stürchler, D; Wyss, R
An estimated 20,000 to 30,000 cases of imported malaria are annually diagnosed in industrialised countries. Some 700 of them concern Swiss travellers and foreign guests. Exposure prophylaxis and chemoprophylaxis for high risk destinations lower the risk of malarial disease. The latter is defined as regular intake of antimalarial drugs in subtherapeutic dosage in order to suppress the development of clinical disease. Drugs are usually taken from one week before travel until four weeks after return from an endemic area. Mefloquine, doxycycline, chloroquine plus proguanil, and presumably soon also atovaquone plus proguanil are available in Switzerland for chemoprophylaxis.
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.
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
Bomblies, Arne; Duchemin, Jean-Bernard; Eltahir, Elfatih A. B.
We present a coupled hydrology and entomology model for the mechanistic simulation of local-scale response of malaria transmission to hydrological and climatological determinants in semiarid, desert fringe environments. The model is applied to the Sahel village of Banizoumbou, Niger, to predict interannual variability in malaria vector mosquito populations that lead to variations in malaria transmission. Using a high-resolution, small-scale distributed hydrology model that incorporates remotely sensed data for land cover and topography, we simulate the formation and persistence of the pools constituting the primary breeding habitat of Anopheles gambiae s.l. mosquitoes, the principal regional malaria vector mosquitoes. An agent-based mosquito population model is coupled to the distributed hydrology model, with aquatic-stage and adult-stage components. Through a dependence of aquatic-stage mosquito development and adult emergence on pool persistence, we model small-scale hydrology as a dominant control of mosquito abundance. For each individual adult mosquito, the model tracks attributes relevant to population dynamics and malaria transmission, which are updated as mosquitoes interact with their environment, humans, and animals. Weekly field observations were made in 2005 and 2006. A 16% increase in rainfall between the two years was accompanied by a 132% increase in mosquito abundance between 2005 and 2006. The model reproduces mosquito population variability at seasonal and interannual timescales and highlights individual pool persistence as a dominant control. Future developments of the presented model can be used in the evaluation of impacts of climate change on malaria, as well as the a priori evaluation of environmental management-based interventions.
Eisele, Thomas P; Miller, John M; Moonga, Hawela B; Hamainza, Busiku; Hutchinson, Paul; Keating, Joseph
We examined the relationship between insecticide-treated mosquito nets (ITNs), malaria parasite infection, and severe anemia prevalence in children in Luangwa District, Zambia, an area with near-universal ITN coverage, at the end of the 2008 and 2010 malaria transmission seasons. Malaria parasite infection prevalence among children < 5 years old was 9.7% (95% confidence interval [CI] = 8.0-11.4%) over both survey years. Prevalence of severe anemia among children 6-59 months old was 6.9% (95% CI = 5.4-8.5%) over both survey years. Within this context of near-universal ITN coverage, we were unable to detect a significant association between malaria parasite or severe anemia prevalence and ITNs (possession and use). In addition to maintaining universal ITN coverage, it will be essential for the malaria control program to achieve high ITN use and laboratory diagnosis and treatment of all fevers among all age groups to further reduce the malaria burden in this area.
Stassinopoulos, E. G.; Goldberg, R. A.; Vette, J. I.; Felton, L. L.
Seasonal global maps of the dark current produced by corpuscular radiation contributing to the background level of the Nimbus-4 Backscattered Ultraviolet (BUV) instrument were developed, using BUV monochrometer nighttime data in the pulse counting mode during solar and magnetically quiet periods. The existence of high intensity surges has been discovered which occur on a sporadic basis and which cause sufficient enhancements of dark current within the subauroral regions to produce background levels similar to those within the South Atlantic anomaly. Examples are provided of the nominal quiet dark current intensity maps, and the variability and implications of the surge data are discussed.
Tagesson, T.; Mastepanov, M.; Tamstorf, M. P.; Eklundh, L.; Schubert, P.; Ekberg, A.; Sigsgaard, C.; Christensen, T. R.; Strom, L.
Arctic ecosystems play a key role in the terrestrial carbon cycle. Recent studies have shown a greening trend and indicated an increase in CO2 uptake in boreal and sub- to low-Arctic areas. Our aim was to combine satellite-based normalized difference vegetation index (NDVI) with ground-based flux measurements of CO2 to investigate possible changes in gross primary production (GPP) for the peak of the growing season between 1992 and 2008 in the high-Arctic. As study area we used a 1.4 km2 rectangle surrounding Rylekaerene, a wet tundra ecosystem situated in the Zackenberg Research Area (74o28 N 20o34 W), North Eastern Greenland. We combined the light use efficiency (LUE) model (GPP= ɛ × PAR × FAPAR, where ɛ is the light use efficiency of the vegetation, PAR is the incoming photosynthetically active radiation and FAPAR the PAR absorbed by the green vegetation) with NDVI data derived from a set of peak growing season satellite images from 1992 to 2008. The LUE-modelled results show a substantial increase in peak-growing season GPP in Rylekaerene during the period. The GPP increase was accompanied by a strong increase in CO2 concentration and air temperature. Possibly, indicating that the increase in GPP was due to the substantial increase in local air temperature, possibly in combination with CO2 fertilization. To model GPP, we first parameterized the LUE-model for the vegetation types dominating the Rylekaerene for the peak of the growing season (peak). Average noon-time PAR measured on the days with satellite images was used as incoming PAR in the model. We found a significant linear relationship between ground-based FAPARpeak and NDVI. The ɛpeak was on average 1.78 g CO2 MJ-1 for this high-Arctic wet tundra ecosystem, which is reasonable for high-Arctic ecosystems. The model was evaluated against field-measured GPP. There were large model uncertainties. This was caused by large natural variation in the field measurements which the model was based upon and
Tiono, Alfred B; Kaboré, Youssouf; Traoré, Abdoulaye; Convelbo, Nathalie; Pagnoni, Franco; Sirima, Sodiomon B
Background Home Management of Malaria (HMM) is one of the key strategies to reduce the burden of malaria for vulnerable population in endemic countries. It is based on the evidence that well-trained communities health workers can provide prompt and adequate care to patients close to their homes. The strategy has been shown to reduce malaria mortality and severe morbidity and has been adopted by the World Health Organization as a cornerstone of malaria control in Africa. However, the potential fall-out of this community-based strategy on the work burden at the peripheral health facilities level has never been investigated. Methods A two-arm interventional study was conducted in a rural health district of Burkina Faso. The HMM strategy has been implemented in seven community clinics catchment's area (intervention arm). For the other seven community clinics in the control arm, no HMM intervention was implemented. In each of the study arms, presumptive treatment was provided for episodes of fevers/malaria (defined operationally as malaria). The study drug was artemether-lumefantrine, which was sold at a subsidized price by community health workers/Key opinion leaders at the community level and by the pharmacists at the health facility level. The outcome measured was the proportion of malaria cases among all health facility attendance (all causes diseases) in both arms throughout the high transmission season. Results A total of 7,621 children were enrolled in the intervention arm and 7,605 in the control arm. During the study period, the proportions of malaria cases among all health facility attendance (all causes diseases) were 21.0%, (445/2,111, 95% CI [19.3%–22.7%]) and 70.7% (2,595/3,671, 95% CI 68.5%–71.5%), respectively in the intervention and control arms (p << 0.0001). The relative risk ratio for a fever/malaria episode to be treated at the HF level was 30% (0.30 < RR < 0.32). The number of malaria episodes treated in the intervention arm was much higher
Moreno, V; Bach, J; Font, Ll; Baixeras, C; Zarroca, M; Linares, R; Roqué, C
Soil radon levels of the Amer fault zone have been measured for a 4 year-period with the aim of checking seasonal fluctuations obtained in previous studies and to understand radon origin and dynamics. In this manuscript additional results are presented: updated continuous and integrated soil radon measurements, radionuclide content of soil materials and a detailed analysis of an urban profile by means of the electrical resistivity imaging technique and punctual soil radon, thoron and CO2 measurements. Integrated and continuous measurements present a wide range of values, [0.2-151.6] kBq m(-3) for radon, [4.5-39.6] kBq m(-3) for thoron and [4.0-71.2] g m(-2) day(-1) for CO2. The highest soil radon levels in the vicinity of the Amer fault (>40 kBq m(-3)) are found close to the fractured areas and present very important fluctuations repeated every year, with values in summer much higher than in winter, confirming previous studies. The highest radon values, up to 150 kBq m(-3), do not have a local origin because the mean value of radium concentration in this soil (19 ± 5 Bq kg(-1)) could not explain these values. Then soil radon migration through the fractures, influenced by atmospheric parameters, is assumed to account for such a high seasonal fluctuation. As main conclusion, in fractured areas, seasonal variations of soil radon concentration can be very important even in places where average soil radon concentration and radium content are not especially high. In these cases the migration capability of the soil is given not by intrinsic permeability but by the fracture structure. Potential risk estimation based on soil radon concentration and intrinsic permeability must be complemented with geological information in fractured systems.
Carter, R.; Mendis, K. N.; Roberts, D.
Malaria transmission is strongly associated with location. This association has two main features. First, the disease is focused around specific mosquito breeding sites and can normally be transmitted only within certain distances from them: in Africa these are typically between a few hundred metres and a kilometre and rarely exceed 2-3 kilometres. Second, there is a marked clustering of persons with malaria parasites and clinical symptoms at particular sites, usually households. In localities of low endemicity the level of malaria risk or case incidence may vary widely between households because the specific characteristics of houses and their locations affect contact between humans and vectors. Where endemicity is high, differences in human/vector contact rates between different households may have less effect on malaria case incidences. This is because superinfection and exposure-acquired immunity blur the proportional relationship between inoculation rates and case incidences. Accurate information on the distribution of malaria on the ground permits interventions to be targeted towards the foci of transmission and the locations and households of high malaria risk within them. Such targeting greatly increases the effectiveness of control measures. On the other hand, the inadvertent exclusion of these locations causes potentially effective control measures to fail. The computerized mapping and management of location data in geographical information systems should greatly assist the targeting of interventions against malaria at the focal and household levels, leading to improved effectiveness and cost-effectiveness of control. PMID:11196487
Reboreda, Rosa; Nolasco, Rita; Castro, Carmen G.; Álvarez-Salgado, Xosé A.; Cordeiro, Nuno G. F.; Queiroga, Henrique; Dubert, Jesus
The seasonal variability of plankton in the entire Iberian margin and the adjacent oceanic region was simulated by applying a NPZD-type biogeochemical model coupled to a physical high resolution configuration of the 3D Regional Ocean Modeling System (ROMS). The NPZD model simulated the time and space evolution of nitrate, phytoplankton/chlorophyll, zooplankton and detritus. Model results were compared to remotely sensed sea surface temperature from AVHRR, mixed layer depth from ARGO floats, and sea surface chlorophyll-a from a monthly SeaWiFS climatology. The model was able to reasonably reproduce the seasonal cycle of phytoplankton biomass in the Iberian Atlantic margin and the adjacent oceanic region. It allowed us to make a general characterization of the spatio-temporal patterns of phytoplankton and zooplankton biomass, as well as detritus and nitrate distribution. However, some limitations in the model were revealed by the Taylor Diagrams analysis. The model seemed to overestimate the offshore spring phytoplankton bloom and the upwelling-related coastal maxima of chlorophyll-a in the shelf. On the other hand, winter chlorophyll-a decrease simulated by the model over the shelf agreed with in situ samplings reported in the literature, contrasting with the high chlorophyll-a estimations of satellite data. This evidenced that care should be taken when validating model results in the Iberian coastal region using satellite chlorophyll-a products, particularly in winter.
Lee, R. F.; Abbott, R. E.; Knox, H. A.; Pancha, A.
We present results demonstrating seasonal variations in the Horizontal-to-Vertical Spectral Ratio (HVSR) at high-latitude seismic stations. We analyze data from two sites at Poker Flat Research Range, near Fairbanks, Alaska. From the first site, we analyze 3 stations installed by Sandia National Labs (SNL) in a valley with marshy summer conditions. We also analyze the PASSCAL Instrument Center station PIC2, which is installed on rock approximately 3.2 km from the SNL stations. These stations continuously record data at 125 (SNL) and 200 (PIC2) samples per second. Seasonal changes in HVSR at high frequencies (> 20 Hz) appear to be caused by impedance contrasts between frozen and thawed ground. Thawed active layers are known to have slower shear-wave velocities than frozen layers or bedrock. An estimate of active layer thickness at each station is obtained from the quarter-wavelength approximation. We verify the accuracy of this technique by obtaining ground-truth measurements at the sites for both thickness and shear-wave velocity. We use physical probing for the thickness measurements and active-source Refraction-Microtremor (ReMi) surveys for the shear-wave velocities. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000
Bieroza, M. Z.; Heathwaite, A. L.
High-resolution in situ total phosphorus (TP), total reactive phosphorus (TRP) and turbidity (TURB) time series are presented for a groundwater-dominated agricultural catchment. Meta-analysis of concentration-discharge (c-q) intra-storm signatures for 61 storm events revealed dominant hysteretic patterns with similar frequency of anti-clockwise and clockwise responses; different determinands (TP, TRP, TURB) behaved similarly. We found that the c-q loop direction is controlled by seasonally variable flow discharge and temperature whereas the magnitude is controlled by antecedent rainfall. Anti-clockwise storm events showed lower flow discharge and higher temperature compared to clockwise events. Hydrological controls were more important for clockwise events and TP and TURB responses, whereas in-stream biogeochemical controls were important for anti-clockwise storm events and TRP responses. Based on the best predictors of the direction of the hysteresis loops, we calibrated and validated a simple fuzzy logic inference model (FIS) to determine likely direction of the c-q responses. We show that seasonal and inter-storm succession in clockwise and anti-clockwise responses corroborates the transition in P transport from a chemostatic to an episodic regime. Our work delivers new insights for the evidence base on the complexity of phosphorus dynamics. We show the critical value of high-frequency in situ observations in advancing understanding of freshwater biogeochemical processes.
Bougeois, Laurie; Tindall, Julia; de Rafélis, Marc; Reichart, Gert-Jan; de Nooijer, Lennart; Dupont-Nivet, Guillaume
Modern Asian climate is mainly controlled by seasonal reverse winds driven by continent-ocean thermal contrast. This yields monsoon pattern characterized by a strong seasonality in terms of precipitation and temperature and a duality between humidity along southern and eastern Asia and aridity in Central Asia. According to climate models, Asian Monsoons and aridification have been governed by Tibetan plateau uplift, global climate changes and the retreat of a vast epicontinental sea (the Proto-Paratethys sea) that used to cover Eurasia in Eocene times (55 to 34 Myr ago). Evidence for Asian aridification and monsoons a old as Eocene, are emerging from proxy and model data, however, the role of the Proto-Paratethys sea remains to be established by proxy data. By applying a novel infra-annual geochemical multi-proxy methodology on Eocene oyster shells of the Proto-Paratethys sea and comparing results to climate simulations, we show that the Central Asian region was generally arid with high seasonality from hot and arid summers to wetter winters. This high seasonality in Central Asia supports a monsoonal circulation was already established although the climate pattern was significantly different than today. During winter months, a strong influence of the Proto-Paratethys moisture is indicated by enhanced precipitations significantly higher than today. Precipitation probably dwindled because of the subsequent sea retreat as well as the uplift of the Tibetan and Pamir mountains shielding the westerlies. During Eocene summers, the local climate was hotter and more arid than today despite the presence of the Proto Paratethys. This may be explained by warmer Eocene global conditions with a strong anticyclonic Hadley cell descending at Central Asian latitudes (25 to 45 N). urthermore, the Tibetan plateau emerging at this time to the south must have already contributed a stronger Foehn effect during summer months bringing warm and dry air into Central Asia. Proto
Gryseels, Charlotte; Uk, Sambunny; Sluydts, Vincent; Durnez, Lies; Phoeuk, Pisen; Suon, Sokha; Set, Srun; Heng, Somony; Siv, Sovannaroth; Gerrets, René; Tho, Sochantha; Coosemans, Marc; Peeters Grietens, Koen
In Cambodia, despite an impressive decline in prevalence over the last 10 years, malaria is still a public health problem in some parts of the country. This is partly due to vectors that bite early and outdoors reducing the effectiveness of measures such as Long-Lasting Insecticidal Nets. Repellents have been suggested as an additional control measure in such settings. As part of a cluster-randomized trial on the effectiveness of topical repellents in controlling malaria infections at community level, a mixed-methods study assessed user rates and determinants of use. Repellents were made widely available and Picaridin repellent reduced 97% of mosquito bites. However, despite high acceptability, daily use was observed to be low (8%) and did not correspond to the reported use in surveys (around 70%). The levels of use aimed for by the trial were never reached as the population used it variably across place (forest, farms and villages) and time (seasons), or in alternative applications (spraying on insects, on bed nets, etc.). These findings show the key role of human behavior in the effectiveness of malaria preventive measures, questioning whether malaria in low endemic settings can be reduced substantially by introducing measures without researching and optimizing community involvement strategies. PMID:26574048
Arbelaez, A. C.; Román-Botero, R.; Gómez-Giraldo, A.; Toro, M.
A research was conducted to identify the dominant basin scale and season evolution of the physical processes in Riogrande II and La Fe, two high mountain Andean tropical reservoirs (>2000 masl), of different size and form, located in the northwestern of Colombia, Southamerica. Eight field campaigns were conducted in each reservoir between 2010 and 2012. Temperature, conductivity and turbidity profiles were measured along the longitudinal axes with a CTD and inflow temperature was recorded continuously with thermistors. In addition, thermistor chains were deployed on the deepest zone of each reservoir, in 2011 in La Fe and in 2013 in Riogrande II. The heat surface fluxes were calculated based on weather measurements, using heat bulk-formulations. It was found that the seasonal variability of the thermal structure in both reservoirs was dominated mainly by changes in the inflows temperature, related to the hydrological cycle, and not by the solar radiation variability. The atmospheric net heat flux revealed low seasonal changes, with the larger variability due to cloud cover and wind speed variability associated to the passage of the Intertropical Convergence Zone. The effect of the net atmospheric flux was confined to the surface mixed layer, which thickness varied between 2 and 4 m by the effect of short wave radiation heating during the day and strong heat loss starting at mid afternoon and remaining through the night. The inflow temperature was inversely correlated to the discharge, so large inflows are also colder and denser than small inflows. The plumes from small inflows are intrusive and create an intermediate layer of young water while those of large inflows remain attached to the bottom and fill the reservoir from the bottom. This resulted in the thermal structure of both reservoirs developing a bimodal annual cycle that follows the bimodal distribution of the rainfall and river discharge. Due to the discharge related changing level of the intrusion of the
Pascale, Salvatore; Lucarini, Valerio; Feng, Xue; Porporato, Amilcare; ul Hasson, Shabeh
In this diagnostic study we analyze changes of rainfall seasonality and dry spells by the end of the twenty-first century under the most extreme IPCC5 emission scenario (RCP8.5) as projected by twenty-four coupled climate models contributing to Coupled Model Intercomparison Project 5 (CMIP5). We use estimates of the centroid of the monthly rainfall distribution as an index of the rainfall timing and a threshold-independent, information theory-based quantity such as relative entropy (RE) to quantify the concentration of annual rainfall and the number of dry months and to build a monsoon dimensionless seasonality index (DSI). The RE is projected to increase, with high inter-model agreement over Mediterranean-type regions—southern Europe, northern Africa and southern Australia—and areas of South and Central America, implying an increase in the number of dry days up to 1 month by the end of the twenty-first century. Positive RE changes are also projected over the monsoon regions of southern Africa and North America, South America. These trends are consistent with a shortening of the wet season associated with a more prolonged pre-monsoonal dry period. The extent of the global monsoon region, characterized by large DSI, is projected to remain substantially unaltered. Centroid analysis shows that most of CMIP5 projections suggest that the monsoonal annual rainfall distribution is expected to change from early to late in the course of the hydrological year by the end of the twenty-first century and particularly after year 2050. This trend is particularly evident over northern Africa, southern Africa and western Mexico, where more than 90 % of the models project a delay of the rainfall centroid from a few days up to 2 weeks. Over the remaining monsoonal regions, there is little inter-model agreement in terms of centroid changes.
Bomblies, A.; Eltahir, E.; Duchemin, J.
A coupled hydrology and entomology model for simulation of malaria transmission and malaria transmitting mosquito population dynamics is presented. Model development and validation is done using field data and observations collected at Banizoumbou and Zindarou, Niger spanning three wet seasons, from 2005 through 2007. The primary model objective is the accurate determination of climate variability effects on village scale malaria transmission. Malaria transmission dependence on climate variables is highly nonlinear and complex. Temperature and humidity affect mosquito longevity, temperature controls parasite development rates in the mosquito as well as subadult mosquito development rates, and precipitation determines the formation and persistence of adequate breeding pools. Moreover, unsaturated zone hydrology influences overland flow, and climate controlled evapotranspiration rates and root zone uptake therefore also influence breeding pool formation. High resolution distributed hydrologic simulation allows representation of the small-scale ephemeral pools that constitute the primary habitat of Anopheles gambiae mosquitoes, the dominant malaria vectors in the Niger Sahel. Remotely sensed soil type, vegetation type, and microtopography rasters are used to assign the distributed parameter fields for simulation of the land surface hydrologic response to precipitation and runoff generation. Predicted runoff from each cell flows overland and into topographic depressions, with explicit representation of infiltration and evapotranspiration. The model's entomology component interacts with simulated pools. Subadult (aquatic stage) mosquito breeding is simulated in the pools, and water temperature dependent stage advancement rates regulate adult mosquito emergence into the model domain. Once emerged, adult mosquitoes are tracked as independent individual agents that interact with their immediate environment. Attributes relevant to malaria transmission such as gonotrophic
Cabezón Estévanez, Itxasne; Górgolas Hernández-Mora, Miguel
Malaria is the most important parasitic disease worldwide, being a public health challenge in more than 90 countries. The incidence of pulmonary manifestations has increased in recent years. Acute respiratory distress syndrome is the most severe form within the pulmonary complications of malaria, with high mortality despite proper management. This syndrome manifests with sudden dyspnoea, cough and refractory hypoxaemia. Patients should be admitted to intensive care units and treated with parenteral antimalarial drug treatment and ventilatory and haemodynamic support without delay. Therefore, dyspnoea in patients with malaria should alert clinicians, as the development of respiratory distress is a poor prognostic factor.
Lukianova-Hleb, Ekaterina; Bezek, Sarah; Szigeti, Reka; Khodarev, Alexander; Kelley, Thomas; Hurrell, Andrew; Berba, Michail; Kumar, Nirbhay; D’Alessandro, Umberto
A fast, precise, noninvasive, high-throughput, and simple approach for detecting malaria in humans and mosquitoes is not possible with current techniques that depend on blood sampling, reagents, facilities, tedious procedures, and trained personnel. We designed a device for rapid (20-second) noninvasive diagnosis of Plasmodium falciparum infection in a malaria patient without drawing blood or using any reagent. This method uses transdermal optical excitation and acoustic detection of vapor nanobubbles around intraparasite hemozoin. The same device also identified individual malaria parasite–infected Anopheles mosquitoes in a few seconds and can be realized as a low-cost universal tool for clinical and field diagnoses. PMID:26079141
Lukianova-Hleb, Ekaterina; Bezek, Sarah; Szigeti, Reka; Khodarev, Alexander; Kelley, Thomas; Hurrell, Andrew; Berba, Michail; Kumar, Nirbhay; D'Alessandro, Umberto; Lapotko, Dmitri
A fast, precise, noninvasive, high-throughput, and simple approach for detecting malaria in humans and mosquitoes is not possible with current techniques that depend on blood sampling, reagents, facilities, tedious procedures, and trained personnel. We designed a device for rapid (20-second) noninvasive diagnosis of Plasmodium falciparum infection in a malaria patient without drawing blood or using any reagent. This method uses transdermal optical excitation and acoustic detection of vapor nanobubbles around intraparasite hemozoin. The same device also identified individual malaria parasite-infected Anopheles mosquitoes in a few seconds and can be realized as a low-cost universal tool for clinical and field diagnoses.
Leena, P. P.; Pandithurai, G.; Anilkumar, V.; Murugavel, P.; Sonbawne, S. M.; Dani, K. K.
Atmospheric aerosols which serve as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. In the present work, aerosol-CCN variability and their relationship have been studied for the first time at Mahabaleshwar, a high altitude (1348 m AMSL) site in Western Ghats, using one year (June 2012-May 2013) of observations. Present study has been done in two sections in which first temporal variability (diurnal and seasonal) of aerosol and CCN has been analyzed. Later CCN to aerosol ratio and other microphysical properties have been investigated along with detail discussion on possible sources of aerosol. First part, i.e., diurnal variation in aerosol and CCN concentration has shown relatively higher values during early morning hours in monsoon season whereas in winter and pre-monsoon it was higher in the evening hours. Seasonal mean variation in aerosol and CCN (SS above 0.6 %) has shown higher (less) in monsoon (winter) season. Temporal variation reveals dominance of fine-mode aerosol during monsoon season over the study region. In the second part temporal variation of activation ratio, k value (exponent of CCN super-saturation spectra) and geometric mean aerosol diameter have been analyzed. Variation of activation ratio showed the ratio is higher in monsoon especially for SS 0.6-1 %. The analysis also showed high k value during monsoon season as compared to other seasons (pre-monsoon and winter) which may be due to dominance of hygroscopic aerosols in the maritime air masses from Arabian Sea and biogenic aerosol emissions from the wet forest. Analyzed mean aerosol diameter is much smaller during monsoon season with less variability compared to other seasons. Overall analysis showed that aerosol and CCN concentration was higher over this high altitude site despite of dominant sink processes such as cloud scavenging and washout mechanisms indicating local emissions and biogenic Volatile Organic Compounds (BVOC) emissions from wet forest
Cui, Liwang; Yan, Guiyun; Sattabongkot, Jetsumon; Cao, Yaming; Chen, Bin; Chen, Xiaoguang; Fan, Qi; Fang, Qiang; Jongwutiwes, Somchai; Parker, Daniel; Sirichaisinthop, Jeeraphat; Kyaw, Myat Phone; Su, Xin-zhuan; Yang, Henglin; Yang, Zhaoqing; Wang, Baomin; Xu, Jianwei; Zheng, Bin; Zhong, Daibin; Zhou, Guofa
The Greater Mekong Subregion (GMS), comprised of six countries including Cambodia, China's Yunnan Province, Lao PDR, Myanmar (Burma), Thailand and Vietnam, is one of the most threatening foci of malaria. Since the initiation of the WHO's Mekong Malaria Program a decade ago, malaria situation in the GMS has greatly improved, reflected in the continuous decline in annual malaria incidence and deaths. However, as many nations are moving towards malaria elimination, the GMS nations still face great challenges. Malaria epidemiology in this region exhibits enormous geographical heterogeneity with Myanmar and Cambodia remaining high-burden countries. Within each country, malaria distribution is also patchy, exemplified by ‘border malaria’ and ‘forest malaria’ with high transmission occurring along international borders and in forests or forest fringes, respectively. ‘Border malaria’ is extremely difficult to monitor, and frequent malaria introductions by migratory human populations constitute a major threat to neighboring, malaria-eliminating countries. Therefore, coordination between neighboring countries is essential for malaria elimination from the entire region. In addition to these operational difficulties, malaria control in the GMS also encounters several technological challenges. Contemporary malaria control measures rely heavily on effective chemotherapy and insecticide control of vector mosquitoes. However, the spread of multidrug resistance and potential emergence of artemisinin resistance in Plasmodium falciparum make resistance management a high priority in the GMS. This situation is further worsened by the circulation of counterfeit and substandard artemisinin-related drugs. In most endemic areas of the GMS, P. falciparum and P. vivax coexist, and in recent malaria control history, P. vivax has demonstrated remarkable resilience to control measures. Deployment of the only registered drug (primaquine) for the radical cure of vivax malaria is
Bhumiratana, Adisak; Sorosjinda-Nunthawarasilp, Prapa; Kaewwaen, Wuthichai; Maneekan, Pannamas; Pimnon, Suntorn
Rubber forestry is intentionally used as a land management strategy. The propagation of rubber plantations in tropic and subtropic regions appears to influence the economical, sociological and ecological aspects of sustainable development as well as human well-being and health. Thailand and other Southeast Asian countries are the world's largest producers of natural rubber products; interestingly, agricultural workers on rubber plantations are at risk for malaria and other vector-borne diseases. The idea of malaria-associated rubber plantations (MRPs) encompasses the complex epidemiological settings that result from interactions among human movements and activities, land cover/land use changes, agri-environmental and climatic conditions and vector population dynamics. This paper discusses apparent issues pertaining to the connections between rubber plantations and the populations at high risk for malaria. The following questions are addressed: (i) What are the current and future consequences of rubber plantations in Thailand and Southeast Asia relative to malaria epidemics or outbreaks of other vector-borne diseases? (ii) To what extent is malaria transmission in Thailand related to the forest versus rubber plantations? and (iii) What are the vulnerabilities of rubber agricultural workers to malaria, and how contagious is malaria in these areas?
Antimalarial drugs will be essential tools at all stages of malaria elimination along the path towards eradication, including the early control or “attack” phase to drive down transmission and the later stages of maintaining interruption of transmission, preventing reintroduction of malaria, and eliminating the last residual foci of infection. Drugs will continue to be used to treat acute malaria illness and prevent complications in vulnerable groups, but better drugs are needed for elimination-specific indications such as mass treatment, curing asymptomatic infections, curing relapsing liver stages, and preventing transmission. The ideal malaria eradication drug is a coformulated drug combination suitable for mass administration that can be administered in a single encounter at infrequent intervals and that results in radical cure of all life cycle stages of all five malaria species infecting humans. Short of this optimal goal, highly desirable drugs might have limitations such as targeting only one or two parasite species, the priorities being Plasmodium falciparum and Plasmodium vivax. The malaria research agenda for eradication should include research aimed at developing such drugs and research to develop situation-specific strategies for using both current and future drugs to interrupt malaria transmission. PMID:21311580
The Malaria Policy Advisory Committee to the World Health Organization met for the first time from 31 January to 2 February 2012 in Geneva, Switzerland. This article provides a summary of the discussions, conclusions and recommendations from that meeting, as part of the newly launched Malaria Journal thematic series “WHO Malaria Policy Advisory Committee: Reports and Recommendations”. Summaries are provided, referencing the relevant background documents, for the meeting sessions on global malaria control, drug resistance and containment, rapid diagnostic test procurement criteria, larviciding, classification of countries for elimination, estimating malaria cases and deaths, and seasonal malaria chemoprevention. Policy statements, position statements, and guidelines that will arise from the MPAC meeting conclusions and recommendations will be formally issued and disseminated to World Health Organization member states by the World Health Organization Global Malaria Programme. PMID:22545931
Borgella, Sophie; Fievet, Nadine; Huynh, Bich-Tram; Ibitokou, Samad; Hounguevou, Gbetognon; Affedjou, Jacqueline; Sagbo, Jean-Claude; Houngbegnon, Parfait; Guezo-Mévo, Blaise; Massougbodji, Achille; Luty, Adrian J. F.
Background Infants of mothers with placental Plasmodium falciparum infections at delivery are themselves more susceptible to malaria attacks or to infection in early life. Methodology/ Principal Findings To assess the impact of either the timing or the number of pregnancy-associated malaria (PAM) infections on the incidence of parasitemia or malaria attacks in infancy, we followed 218 mothers through pregnancy (monthly visits) up to delivery and their infants from birth to 12 months of age (fortnightly visits), collecting detailed clinical and parasitological data. After adjustment on location, mother’s age, birth season, bed net use, and placental malaria, infants born to a mother with PAM during the third trimester of pregnancy had a significantly increased risk of infection (OR [95% CI]: 4.2 [1.6; 10.5], p = 0.003) or of malaria attack (4.6 [1.7; 12.5], p = 0.003). PAM during the first and second trimesters had no such impact. Similarly significant results were found for the effect of the overall number of PAM episodes on the time to first parasitemia and first malaria attack (HR [95% CI]: 2.95 [1.58; 5.50], p = 0.001 and 3.19 [1.59; 6.38], p = 0.001) respectively. Conclusions/ Significance This study highlights the importance of protecting newborns by preventing repeated episodes of PAM in their mothers. PMID:24236190
Houghton, D L
Cerebral malaria with psychosomatic manifestations is one aspect of malaria which may be mistaken for mental illness. However, the psychosomatic aspects of the disease also relate to the biological, psychological and social influences which may determine changes in disease incidence and distribution. The history of the Global Malaria Eradication Campaign and the resurgence of malaria in many countries of the world have influenced attitudes and the professional milieu in which present day malaria control programmes seek to operate. The individual in a malarious area may obstruct malaria control operations by refusing to allow indoor spraying or to take prophylactic medication. Cultural beliefs often described the history of malaria in a community and the way in which the community had come to terms with this disease. Socio-economic development and population movement may disturb this equilibrium and result in a rise in malaria incidence. Behavioural habits may increase malaria risk and the degree to which the community is prepared to become involved in malaria control may influence its experience with the disease.
Purkhús, Elisabeth; Krustrup, Peter; Mohr, Magni
Purkhús, E, Krustrup, P, and Mohr, M. High-intensity training improves exercise performance in elite women volleyball players during a competitive season. J Strength Cond Res 30(11): 3066-3072, 2016-Elite women volleyball players (n = 25; mean ± SD: age, 19 ± 5 years; height, 171 ± 7 cm; weight, 63 ± 10 kg) volunteered to participate in the study. They were randomized into a high-intensity training (HIT; n = 13) group and a control (CON; n = 12) group. In addition to the normal team training and games, HIT performed 6-10 × 30-seconds all-out running intervals separated by 3-minute recovery periods 3 times per week during a 4-week in-season period whereas CON only completed the team training sessions and games. Preintervention and postintervention, all players completed the arrowhead agility test (AAT), a repeated sprint test (RST; 5 × 30 meters separated by 25 seconds of recovery), and the Yo-Yo Intermittent Recovery level 2 test (Yo-Yo IR2) followed by a-10 minute rest period and the Yo-Yo IR1 test. Mean running distance during HIT in week 1 was 152 ± 4 m and increased (p ≤ 0.05) by 4.6% (159 ± 3 m) in week 4. The AAT performance improved (p ≤ 0.05) by 2.3% (18.87 ± 0.97-18.44 ± 1.06 seconds) and RST by 4.3% postintervention in the HIT group only. Baseline RST fatigue index was 7.0 ± 2.9 and 6.2 ± 5.0% in HIT and CON, respectively, but was lowered (p ≤ 0.05) to 2.7 ± 3.0% posttraining in HIT and remained unaltered in CON (5.5 ± 5.0%). In HIT, Yo-Yo IR2 and Yo-Yo IR1 performance improved by 12.6 and 18.3% postintervention, respectively, with greater (p ≤ 0.05) Yo-yo IR1 change scores than in CON. In conclusion, additional high-intensity in-season training performed as interval running improved agility, repeated sprint ability, and high-intensity intermittent exercise performance in elite women volleyball players.
V, Rakesh; Goswami, Prashant
a limited area model (LAM), the impact of data assimilation is likely to depend on the background state through lateral boundary forcing; this may introduce certain seasonality in the impact of data assimilation on rainfall forecasting. It is also likely that the impact of data assimilation on forecasts will have certain spatial variability. Finally, owing to the convective nature of rainfall and the roles of parameterization scheme, the impact of data assimilation may depend on the category (intensity) of rainfall. Here these aspects for rainfall forecasts at high resolution were examined. Using a LAM (An advanced version of Weather Research and Forecasting Model), we have carried out twin simulations with and without data assimilation; the simulations without data assimilation are used as the benchmark for assessing the impact of data assimilation. Analysis of simulations for 40 sample days distributed over the years 2012-2014 over Karnataka (southern state in India) is carried out to estimate impact of data assimilation. Various statistical measures show that data assimilation improved the rainfall prediction in most cases; however, there is also strong seasonality and location dependence in impact of data assimilation. Our results also show that improvement due to data assimilation is higher/lower for lower/higher rainfall categories. Analysis shows that the cases where the initial states with data assimilation depart strongly from the first guess generally result in less or even negative impact. It is pointed out that the results have important implications in design of observation system and assessment of impact of forecasts.
Ermert, V.; Fink, A. H.; Paeth, H.; Morse, A. P.
The projected climate change will probably alter the range and transmission potential of malaria in Africa. The potential impacts of climate change on the malaria distribution is assessed for tropical Africa. Bias-corrected regional climate projections with a horizontal resolution of 0.5° are used from the Regional Model (REMO), which include land use and land cover changes. The malaria models employed are the 2010 version of the Liverpool Malaria Model (LMM2010), the Garki model, the Plasmodium falciparum infection model from Smith et al. (2005) (S2005), and the Malaria Seasonality Model (MSM) from the Mapping Malaria Risk in Africa project. The results of the models are compared with data from the Malaria Atlas Project (MAP) and novel validation procedures for the LMM2010 and MSM lend more credence to their results. For climate scenarios A1B and B1 and for 2001-2050, REMO projects an overall drying and warming trend in the African malaria belt, that is largely imposed by the man-made degradation of vegetation. As a result, the malaria projections show a decreased malaria spread in West Africa. The northern Sahel is no more suitable for malaria in the projections. More unstable malaria transmission and shorter malaria seasons are expected for various areas farther south. An increase in the malaria epidemic risk is found for more densely populated areas in the southern part of the Sahel. In East Africa, higher temperatures and nearly unchanged precipitation patterns lead to longer transmission seasons and an increase in the area of highland malaria. For altitudes up to 2000 m the malaria transmission stabilises and the epidemic risk is reduced but for higher altitudes the risk of malaria epidemics is increased. The results of the more complex and simple malaria models are similar to each other. However, a different response to the warming of highlands is found for the LMM2010 and MSM. This shows the requirement of a multi model uncertainty analysis for the
Arango, Eliana M.; Samuel, Roshini; Agudelo, Olga M.; Carmona-Fonseca, Jaime; Maestre, Amanda; Yanow, Stephanie K.
Plasmodium infection in pregnancy causes substantial maternal and infant morbidity and mortality. In Colombia, both P. falciparum and P. vivax are endemic, but the impact of either species on pregnancy is largely unknown in this country. A cross-sectional study was carried out with 96 pregnant women who delivered at their local hospital. Maternal, placental, and cord blood were tested for malaria infection by microscopy and real-time quantitative polymerase chain reaction (qPCR). A high frequency of infection was detected by qPCR (45%). These infections had low concentrations of parasite DNA, and 79% were submicroscopic. Submicroscopic infections were associated with placental villitis and intervillitis. In conclusion, the overall frequency of Plasmodium infection at delivery in Colombia is much higher than previously reported. These data prompt a re-examination of the local epidemiology of malaria using molecular diagnostics to establish the clinical relevance of submicroscopic infections during pregnancy as well as their consequences for mothers and newborns. PMID:23716408
Brown, M. G.; Tedesco, M.
The surface hydrology of the Greenland ice sheet plays a crucial role on surface energy and mass balance, as well as on the englacial and sub-glacial environments. The spatial distribution of these surface streams is poorly understood and their temporal variability is (to our knowledge) unknown. One of the reasons for the lack of knowledge on the temporal variability of such streams is related to the historical unavailability of satellite data that could spatially resolve the presence and associated properties of the streams. In recent years, however, multi-spectral commercial satellite data in the visible and infra-red bands have been made available to the scientific community. These newly accessible data sets are provided at spatial resolutions of the order of 1-2 meters, therefore, allowing to perform accurate spatial and temporal analysis of surface streams (and small lakes and ponds that cannot be resolved with sensors such as MODIS or LANDSAT). In this study, we report results concerning the seasonal and intra-seasonal variability of surface streams over a selected area on the west Greenland ice sheet. Using a combination of ENVI® and ArcGIS® software packages applied to multispectral high resolution imagery from World View 2 and Quickbird satellites, surface streams are identified through multiple approaches (either based on unsupervised classifications, band combinations, band ratio thresholds, or digitization) and vector maps of the surface hydrology network were created. Stream networks created during one melting season (at three different stages of the season) were compared and discussed as well as the networks mapped between two consecutive years for proximate dates.
Brown, Michael G.; Tedesco, Marco
The surface hydrology of the Greenland ice sheet plays a crucial role on surface energy and mass balance, as well as on the en-glacial and sub-glacial environments. The spatial distribution of these surface streams is poorly understood and their temporal variability is (to our knowledge) unknown. One of the reasons for the lack of knowledge on the temporal variability of such streams is related to the historical unavailability of satellite data that could spatially resolve the presence and associated properties of the streams. In recent years, however, multi-spectral commercial satellite data in the visible and infra-red bands have been made available to the scientific community. These newly accessible data sets are provided at spatial resolutions of the order of 1-2 meters, therefore, allowing to perform accurate spatial and temporal analysis of surface streams (and small lakes and ponds that cannot be resolved with sensors such as MODIS or LANDSAT). In this study, we report results concerning the seasonal and intra-seasonal variability of surface streams over a selected area on the west Greenland ice sheet. Using ArcGIS® software applied to multispectral high resolution imagery from World View 2 and Quickbird satellites, surface streams were identified through band math, threshold classifications, and morphological operations. Raster and vector maps of the surface hydrology network were created. Stream networks created during multiple melt seasons (at several different stages of the season) were compared and discussed as well as the networks mapped between consecutive years for proximate dates.
Protopopoff, Natacha; Van Bortel, Wim; Speybroeck, Niko; Van Geertruyden, Jean-Pierre; Baza, Dismas; D'Alessandro, Umberto; Coosemans, Marc
Introduction Malaria is re-emerging in most of the African highlands exposing the non immune population to deadly epidemics. A better understanding of the factors impacting transmission in the highlands is crucial to improve well targeted malaria control strategies. Methods and Findings A conceptual model of potential malaria risk factors in the highlands was built based on the available literature. Furthermore, the relative importance of these factors on malaria can be estimated through “classification and regression trees”, an unexploited statistical method in the malaria field. This CART method was used to analyse the malaria risk factors in the Burundi highlands. The results showed that Anopheles density was the best predictor for high malaria prevalence. Then lower rainfall, no vector control, higher minimum temperature and houses near breeding sites were associated by order of importance to higher Anopheles density. Conclusions In Burundi highlands monitoring Anopheles densities when rainfall is low may be able to predict epidemics. The conceptual model combined with the CART analysis is a decision support tool that could provide an important contribution toward the prevention and control of malaria by identifying major risk factors. PMID:19946627
Breeveld, Florence J V; Vreden, Stephen G S; Grobusch, Martin P
Suriname has cleared malaria from its capital city and coastal areas mainly through the successful use of chloroquine and DDT (dichloro-diphenyl-trichloroethane) during the Global Malaria Eradication programme that started in 1955. Nonetheless, malaria transmission rates remained high in the interior of the country for a long time. An impressive decline in malaria cases was achieved in the past few years, from 14,403 registered cases in 2003 to 1,371 in 2009. The introduction of artemisinin-based combination therapy (ACT) in 2004 has further fuelled the decrease in the number of infections with Plasmodium falciparum. The only population group still heavily burdened with malaria is gold mining industry workers. Interestingly, an important part of malaria cases diagnosed and treated in Suriname originate from border regions. Therefore, practical initiatives of combined efforts between neighbouring countries must be scaled up in order to effectively attack these specific areas. Furthermore, it is of vital importance to keep investing into the malaria control programme and public awareness campaigns. Especially the correct use of ACT must be promoted in order to prevent the emergence of resistance. However, effective preventive measures and adequate therapeutic options are on their own not enough to control, let alone eliminate malaria. Changing personal and social behaviour of people is particularly difficult, but crucial in making the current success sustainable. With this in mind, research on successfully implemented interventions, focusing on behavioural modifications and methods of measuring their effectiveness, must be expanded.
Background In arid settings, droughts usually lead to periods of very low or no malaria transmission. However, in rural Kandi (Sonsoro) in northeastern Benin, several malaria cases are often diagnosed during dry seasons. The underlying factors accounting for this phenomenon remain unknown. Methods The entomological profile of Sonsoro has been studied compared to a location in urban Kandi (Gansosso) for a period of one year. During this period, Anopheles larval habitats were investigated and populations of Anopheles gambiae s.l. were sampled by human landing catches in both areas. Enzyme-linked immunosorbent assays (ELISA) for Plasmodium falciparum circumsporozoite protein (CSP) were conducted on vector specimens and the entomological inoculation rates (EIR) were determined per season (wet versus dry) in each area. In addition, during the severe drought period, Rapid Diagnostic Tests (RDTs) were conducted on school children under the age 10 years in these areas to provide a global view of drought-malaria prevalence and to perform a crossing with entomological data in Kandi. Results Overall, An. gambiae s.l. was particularly abundant in rural Kandi compared to the urban area with a significant decrease of vector density in both sites during the dry season. In this period, larval sampling data identified household water sources as potential breeding sites in urban and rural Kandi. We also observed a significant seasonal variation of the infectivity rate in both areas but for each period (season), the EIR was higher in the rural site than in the urban. Data of P. falciparum detection was the reflection of entomological findings. The drought-malaria prevalence was 5.5 times higher in rural Kandi as compared to urban Kandi. The presence of a permanent water site and the low level of urbanization in rural Kandi were identified as a risk factor. Conclusion Our data showed a high level of malaria transmission in the municipality of Kandi. Household water source plays an
Eckart, W U; Vondra, H
The epidemiological and pharmacological fight against malaria and German malaria research during the Nazi dictatorship were completely under the spell of war. The Oberkommando des Heeres (German supreme command of the army) suffered the bitter experience of unexpected high losses caused by malaria especially at the Greek front (Metaxes line) but also in southern Russia and in the Ukraine. Hastily raised anti-malaria units tried to teach soldiers how to use the synthetic malaria drugs (Plasmochine, Atebrine) properly. Overdoses of these drugs were numerous during the first half of the war whereas in the second half it soon became clear that it would not be possible to support the army due to insufficient quantities of plasmochine and atebrine. During both running fights and troop withdrawals at all southern and southeastern fronts there was hardly any malaria prophylaxis or treatment. After war and captivity many soldiers returned home to endure heavy malaria attacks. In German industrial (Bayer, IG-Farben) and military malaria laboratories of the Heeres-Sanitäts-Akademie (Army Medical Academy) the situation was characterised by a hasty search for proper dosages of anti-malaria drugs, adequate mechanical and chemical prophylaxis (Petroleum, DDT, and other insecticides) as well as an anti-malaria vaccine. Most importantly, large scale research for proper atebrine and plasmochine dosages was conducted in German concentration camps and mental homes. In Dachau Professor Claus Schilling tested synthetic malaria drugs and injected helpless prisoners with high and sometimes lethal doses. Since the 1920s he had been furiously looking for an anti-malaria vaccine in Italian mental homes and from 1939 he continued his experiments in Dachau. Similar experiments were also performed in Buchenwald and in a psychiatric clinic in Thuringia, where Professor Gerhard Rose tested malaria drugs with mentally ill Russian prisoners of war. Schilling was put to death for his criminal
Wu, Yujie; Duan, Wansuo; Rong, Xinyao
The seasonal predictability of sea surface temperature anomalies (SSTA) in the Kuroshio-Oyashio Extension (KOE) is explored by performing perfect model predictability experiments from the viewpoint of initial error growth in a global coupled model. It is found that prediction errors of KOE-SSTA always increase in the boreal summer and decrease in the boreal winter. This leads to smaller (larger) prediction errors and higher (lower) prediction skills in boreal winter (summer). This seasonal characteristic of the KOE-SSTA error growth implies a season-dependent predictability that is lower in summer and higher in winter. The mechanism responsible for error growth associated with seasonal predictability is also explored. The error increase in summer and error decrease in winter in the KOE-SSTA are both largely attributed to the seasonal evolution of latent heat flux error and mean temperature advection by vertical current error in the KOE region, both of which are forced by the prediction error of 1 month leading zonal wind stress per unit mass for the mixed layer over the KOE region. The shallowest (deepest) mixed layer in summer (winter) amplifies (reduces) the forcing of zonal wind stress errors on the error growth of KOE-SSTA, thereby causing the seasonal evolution of prediction errors of KOE-SSTA and ultimately resulting in the season-dependent predictability of the KOE-SSTA, i.e., low in summer and high in winter.
Migliani, R; Josse, R; Hovette, P; Keundjian, A; Pages, F; Meynard, J-B; Ollivier, L; Sbai Idrissi, K; Tifratene, K; Orlandi, E; Rogier, C; Boutin, J-P
French troops were sent to the Ivory Coast on September 22, 2002 within the framework of Operation Unicorn in response to the political unrest. From September 22 to October 20, a total of 37 cases of malaria were reported, i.e., 35.7 cases per 1000 man-months. As of October 11, the central headquarters of the Armed Services Health Corps decided to use doxycycline as the exclusive agent for drug prophylaxis in military personnel on duty in the Ivory Coast and to enhance vector control measures. The incidence of malaria decreased to 2 cases per 1000 man-months at the sixth month. A recrudescence of malaria to 15 cases per 1000 man-months was observed with the rainy season in April. During this period one person presenting severe malaria with coma required emergency evacuation to France. In May 2003, several studies were undertaken to determine the factors that caused this recrudescence. These studies included surveys to evaluate awareness concerning malaria and monitor compliance with drug prophylaxis and tolerance of doxycycline, a case-control study to identify factors related to malarious episodes and an entomological study. Awareness of malaria was high with 75% of the 477 respondents stating that malaria could be transmitted by single mosquito bite. The case-control study showed a correlation between occurrence of malarious bouts and non-compliance with drug prophylaxis (p < 10(-5)). The odds-ratio was 3.05 (95% confidence interval, 1.52-6.14) for subjects claiming zero to one incident of non-compliance per week and 7.51 (IC95%, 3.24-17.40) for those claiming more than one incident of non-compliance per week. Tolerance of doxycyline was good since 72% of respondents reported no adverse effects. The main vector was Anopheles gambiae. The number of bites per man per night ranged from 25 to 2 and the number of infected bites ranged from 2 to 3 per week. Treatment was initiated promptly using quinine at a total dose of 25 mg/kg in 3 daily doses for 7 days by the
Moorthy, Vasee S; Kieny, Marie Paule
Gains in the control of malaria and the promising progress of a malaria vaccine that is partly efficacious do not reduce the need for a high-efficacy vaccine in the longer term. Evidence supports the feasibility of developing a highly efficacious malaria vaccine. However, design of candidate malaria vaccines remains empirical and is necessarily based on many unproven assumptions because much of the knowledge needed to design vaccines and to predict efficacy is not available. Data to inform key questions of vaccine science might allow the design of vaccines to progress to a less empirical stage, for example through availability of assay results associated with vaccine efficacy. We discuss six strategic gaps in knowledge that contribute to empiricism in the design of vaccines. Comparative evaluation, assay and model standardisation, greater sharing of information, collaboration and coordination between groups, and rigorous evaluation of existing datasets are steps that can be taken to enable reductions in empiricism over time.
Gascoyne, Peter; Satayavivad, Jutamaad; Ruchirawat, Mathuros
Microfluidic systems are under development to address a variety of medical problems. Key advantages of micrototal analysis systems based on microfluidic technology are the promise of small size and the integration of sample handling and measurement functions within a single, automated device having low mass-production costs. Here, we review the spectrum of methods currently used to detect malaria, consider their advantages and disadvantages, and discuss their adaptability towards integration into small, automated micro total analysis systems. Molecular amplification methods emerge as leading candidates for chip-based systems because they offer extremely high sensitivity, the ability to recognize malaria species and strain, and they will be adaptable to the detection of new genotypic signatures that will emerge from current genomic-based research of the disease. Current approaches to the development of chip-based molecular amplification are considered with special emphasis on flow-through PCR, and we present for the first time the method of malaria specimen preparation by dielectrophoretic field-flow-fractionation. Although many challenges must be addressed to realize a micrototal analysis system for malaria diagnosis, it is concluded that the potential benefits of the approach are well worth pursuing.
Gaudart, Jean; Poudiougou, Belco; Dicko, Alassane; Ranque, Stéphane; Toure, Ousmane; Sagara, Issaka; Diallo, Mouctar; Diawara, Sory; Ouattara, Amed; Diakite, Mahamadou; Doumbo, Ogobara K
Background Spatial and temporal heterogeneities in the risk of malaria have led the WHO to recommend fine-scale stratification of the epidemiological situation, making it possible to set up actions and clinical or basic researches targeting high-risk zones. Before initiating such studies it is necessary to define local patterns of malaria transmission and infection (in time and in space) in order to facilitate selection of the appropriate study population and the intervention allocation. The aim of this study was to identify, spatially and temporally, high-risk zones of malaria, at the household level (resolution of 1 to 3 m). Methods This study took place in a Malian village with hyperendemic seasonal transmission as part of Mali-Tulane Tropical Medicine Research Center (NIAID/NIH). The study design was a dynamic cohort (22 surveys, from June 1996 to June 2001) on about 1300 children (<12 years) distributed between 173 households localized by GPS. We used the computed parasitological data to analyzed levels of Plasmodium falciparum, P. malariae and P. ovale infection and P. falciparum gametocyte carriage by means of time series and Kulldorff's scan statistic for space-time cluster detection. Results The time series analysis determined that malaria parasitemia (primarily P. falciparum) was persistently present throughout the population with the expected seasonal variability pattern and a downward temporal trend. We identified six high-risk clusters of P. falciparum infection, some of which persisted despite an overall tendency towards a decrease in risk. The first high-risk cluster of P. falciparum infection (rate ratio = 14.161) was detected from September 1996 to October 1996, in the north of the village. Conclusion This study showed that, although infection proportions tended to decrease, high-risk zones persisted in the village particularly near temporal backwaters. Analysis of this heterogeneity at the household scale by GIS methods lead to target preventive
Facer, C A; Agiostratidou, G
The majority (75%) of adult patients with uncomplicated Plasmodium falciparum and P. vivax malaria are positive for anti-phospholipid antibodies (aPLA) as demonstrated by ELISA using a panel of anionic and cationic phospholipids. The highest IgG and IgM binding was to the anionic phospholipids, phosphatidylserine (PS), phosphatidic acid (PA) and cardiolipin (CL), but excluding phosphatidylinositol (PI) to which only low antibody levels were found. Comparison of the mean IgG and IgM aPLA showed a trend for anti-PA > CL > PS > PC > PE > PI. Anti-PI levels were compared in two groups of African children, one group with non-severe and the other with severe (cerebral) falciparum malaria. Children with cerebral disease had significantly lower IgM anti-PI. The results are discussed with the view that serum-derived aPLA may have a role in 'anti-disease' immune responses. Their possible role in the opsonization and phagocytosis of parasitized erythrocytes and in thrombocytopenia is also considered. PMID:8306506
Christensen, Janelle J; Castañeda, Heide
This study examined disaster preparedness and decision-making by caregivers of community-dwelling persons diagnosed with Alzheimer's or a related dementia (ADRD). Interviews were conducted with 20 caregivers in South Florida. Twelve of these interviews include caregiving experiences during the highly active 2004-2005 hurricane seasons. Results indicate that persons in earlier stages of ADRD can, and often do, remain engaged in the disaster preparation and planning process. However, during the early stages, persons may also resist evacuation, even if the caregiver felt it was necessary. During later stages of the disease, caregivers reported less resistance to disaster-related decisions, however, with the tradeoff of less ability to assist with preparation.
Pauly, Klaas; Goossens, Rudi; De Clerck, Olivier
PROBA/CHRIS is one of the first satellite sensors to offer both high spatial and spectral resolutions. We explored the potential of this sensor to map the dynamics of seaweed and coral cover in an area influenced by seasonal upwelling in the Arabian Sea. Quantitative field assessments coincided with image acquisitions. After removal of sensor noise and atmospheric effects, maximum likelihood supervised classification yielded a tau accuracy of 64.09 for the summer monsoon dataset. Clearer waters and a lower spatial heterogeneity in the winter monsoon dataset resulted in a tau accuracy of 71.45. Post-classification comparison and vegetation indices illustrated the conspicuous turnover from dense macroalgal stands covering nearly all coral communities during summer to bare rock or turf communities during winter, with coral becoming the predominant bottom type. These results were further analysed using a novel maximum entropy sub-pixel approach and were shown to consistently outperform results from Landsat 7 ETM+ imagery.
Reiner, Robert C; Guerra, Carlos; Donnelly, Martin J; Bousema, Teun; Drakeley, Chris; Smith, David L
A basic quantitative understanding of malaria transmission requires measuring the probability a mosquito becomes infected after feeding on a human. Parasite prevalence in mosquitoes is highly age-dependent, and the unknown age-structure of fluctuating mosquito populations impedes estimation. Here, we simulate mosquito infection dynamics, where mosquito recruitment is modelled seasonally with fractional Brownian noise, and we develop methods for estimating mosquito infection rates. We find that noise introduces bias, but the magnitude of the bias depends on the 'colour' of the noise. Some of these problems can be overcome by increasing the sampling frequency, but estimates of transmission rates (and estimated reductions in transmission) are most accurate and precise if they combine parity, oocyst rates and sporozoite rates. These studies provide a basis for evaluating the adequacy of various entomological sampling procedures for measuring malaria parasite transmission from humans to mosquitoes and for evaluating the direct transmission-blocking effects of a vaccine.
Reiner, Robert C.; Guerra, Carlos; Donnelly, Martin J.; Bousema, Teun; Drakeley, Chris; Smith, David L.
A basic quantitative understanding of malaria transmission requires measuring the probability a mosquito becomes infected after feeding on a human. Parasite prevalence in mosquitoes is highly age-dependent, and the unknown age-structure of fluctuating mosquito populations impedes estimation. Here, we simulate mosquito infection dynamics, where mosquito recruitment is modelled seasonally with fractional Brownian noise, and we develop methods for estimating mosquito infection rates. We find that noise introduces bias, but the magnitude of the bias depends on the ‘colour' of the noise. Some of these problems can be overcome by increasing the sampling frequency, but estimates of transmission rates (and estimated reductions in transmission) are most accurate and precise if they combine parity, oocyst rates and sporozoite rates. These studies provide a basis for evaluating the adequacy of various entomological sampling procedures for measuring malaria parasite transmission from humans to mosquitoes and for evaluating the direct transmission-blocking effects of a vaccine. PMID:26400195
Todd, Richard W; Cole, N Andy; Rhoades, Marty B; Parker, David B; Casey, Kenneth D
Ammonia emitted from beef cattle feedyards adds excess reactive N to the environment, contributes to degraded air quality as a precursor to secondary particulate matter, and represents a significant loss of N from beef cattle feedyards. We used open path laser spectroscopy and an inverse dispersion model to quantify daily, monthly, seasonal, and annual NH emissions during 2 yr from two commercial cattle feedyards in the Panhandle High Plains of Texas. Annual patterns of NH fluxes correlated with air temperature, with the greatest fluxes (>100 kg ha d) during the summer and the lowest fluxes (<15 kg ha d) during the winter. Mean monthly per capita emission rate (PCER) of NH-N at one feedyard ranged from 31 g NH-N head d (January) to 207 g NH-N head d (October), when increased dietary crude protein from wet distillers grains elevated emissions. Ammonia N emissions at the other feedyard ranged from 36 g NH-N head d (January) to 121 g NH-N head d (September). Monthly fractional NH-N loss ranged from a low of 19 to 24% to a high of 80 to 85% of fed N at the two feedyards. Seasonal PCER at the two feedyards averaged 60 to 71 g NH-N head d during winter and 103 to 158 g NH-N head d during summer. Annually, PCER was 115 and 80 g NH-N head d at the two feedyards, which represented 59 and 52% of N fed to the cattle. Detailed studies are needed to determine the effect of management and environmental variables such as diet, temperature, precipitation, and manure water content on NH emissions.
Pernthaler, Jakob; Glöckner, Frank-Oliver; Unterholzner, Stefanie; Alfreider, Albin; Psenner, Roland; Amann, Rudolf
The seasonal variations in community structure and cell morphology of pelagic procaryotes from a high mountain lake (Gossenköllesee, Austria) were studied by in situ hybridization with rRNA-targeted fluorescently labeled oligonucleotide probes (FISH) and image-analyzed microscopy. Compositional changes and biomass fluctuations within the assemblage were observed both in summer and beneath the winter ice cover and are discussed in the context of physicochemical and biotic parameters. Proteobacteria of the beta subclass (beta-proteobacteria) formed a dominant fraction of the bacterioplankton (annual mean, 24% of the total counts), whereas alpha-proteobacteria were of similar relative importance only during spring (mean, 11%). Bacteria of the Cytophaga-Flavobacterium cluster, although less abundant, constituted the largest fraction of the filamentous morphotypes during most of the year, thus contributing significantly to the total microbial biomass. Successive peaks of threadlike and rod-shaped archaea were observed during autumn thermal mixing and the period of ice cover formation, respectively. A set of oligonucleotide probes targeted to single phylotypes was constructed from 16S rRNA-encoding gene clone sequences. Three distinct populations of uncultivated microbes, affiliated with the alpha- and beta-proteobacteria, were subsequently monitored by FISH. About one-quarter of all of the beta-proteobacteria (range, 6 to 53%) could be assigned to only two phylotypes. The bacterial populations studied were annually recurrent, seasonally variable, and vertically stratified, except during the periods of lake overturn. Their variability clearly exceeded the fluctuations of the total microbial assemblage, suggesting that the apparent stability of total bacterioplankton abundances may mask highly dynamic community fluctuations. PMID:9797280
Sharma, V. P.
Malaria control in India has occupied high priority in health sector consuming major resources of the Central and State governments. Several new initiatives were launched from time to time supported by foreign aids but malaria situation has remained static and worsened in years of good rainfall. At times malaria relented temporarily but returned with vengeance at the local, regional and national level, becoming more resilient by acquiring resistance in the vectors and the parasites. National developments to improve the economy, without health impact assessment, have had adverse consequences by providing enormous breeding grounds for the vectors that have become refractory to interventions. As a result, malaria prospers and its control is in dilemma, as finding additional resources is becoming difficult with the ongoing financial crisis. Endemic countries must contribute to make up the needed resources, if malaria is to be contained. Malaria control requires long term planning, one that will reduce receptivity and vulnerability, and uninterrupted financial support for sustained interventions. While this seems to be a far cry, the environment is becoming more receptive for vectors, and epidemics visit the country diverting major resources in their containment, e.g. malaria, dengue and dengue haemorrhagic fevers, and Chikungunya virus infection. In the last six decades malaria has taken deep roots and diversified into various ecotypes, the control of these ecotypes requires local knowledge about the vectors and the parasites. In this review we outline the historical account of malaria and methods of control that have lifted the national economy in many countries. While battles against malaria should continue at the local level, there is a need for large scale environmental improvement. Global Fund for AIDS, Tuberculosis and Malaria has provided huge funds for malaria control worldwide touching US$ 2 billion in 2011. Unfortunately it is likely to decline to US$ 1
Schapira, Allan; Boutsika, Konstantina
To deal with the variability of malaria, control programmes need to stratify their malaria problem into a number of smaller units. Such stratification may be based on the epidemiology of malaria or on its determinants such as ecology. An ecotype classification was developed by the World Health Organization (WHO) around 1990, and it is time to assess its usefulness for current malaria control as well as for malaria modelling on the basis of published research. Journal and grey literature was searched for articles on malaria or Anopheles combined with ecology or stratification. It was found that all malaria in the world today could be assigned to one or more of the following ecotypes: savanna, plains and valleys; forest and forest fringe; foothill; mountain fringe and northern and southern fringes; desert fringe; coastal and urban. However, some areas are in transitional or mixed zones; furthermore, the implications of any ecotype depend on the biogeographical region, sometimes subregion, and finally, the knowledge on physiography needs to be supplemented by local information on natural, anthropic and health system processes including malaria control. Ecotyping can therefore not be seen as a shortcut to determine control interventions, but rather as a framework to supplement available epidemiological and entomological data so as to assess malaria situations at the local level, think through the particular risks and opportunities and reinforce intersectoral action. With these caveats, it does however emerge that several ecotypic distinctions are well defined and have relatively constant implications for control within certain biogeographic regions. Forest environments in the Indo-malay and the Neotropics are, with a few exceptions, associated with much higher malaria risk than in adjacent areas; the vectors are difficult to control, and the anthropic factors also often converge to impose constraints. Urban malaria in Africa is associated with lower risk than savanna
Background To better understand trends in the burden of malaria and their temporal relationship to control activities, a survey was conducted to assess reported cases of malaria and malaria control activities in Mutasa District, Zimbabwe. Methods Data on reported malaria cases were abstracted from available records at all three district hospitals, three rural hospitals and 25 rural health clinics in Mutasa District from 2003 to 2011. Results Malaria control interventions were scaled up through the support of the Roll Back Malaria Partnership, the Global Fund to Fight AIDS, Tuberculosis and Malaria, and The President’s Malaria Initiative. The recommended first-line treatment regimen changed from chloroquine or a combination of chloroquine plus sulphadoxine/pyrimethamine to artemisinin-based combination therapy, the latter adopted by 70%, 95% and 100% of health clinics by 2008, 2009 and 2010, respectively. Diagnostic capacity improved, with rapid diagnostic tests (RDTs) available in all health clinics by 2008. Vector control consisted of indoor residual spraying and distribution of long-lasting insecticidal nets. The number of reported malaria cases initially increased from levels in 2003 to a peak in 2008 but then declined 39% from 2008 to 2010. The proportion of suspected cases of malaria in older children and adults remained high, ranging from 75% to 80%. From 2008 to 2010, the number of RDT positive cases of malaria decreased 35% but the decrease was greater for children younger than five years of age (60%) compared to older children and adults (26%). Conclusions The burden of malaria in Mutasa District decreased following the scale up of malaria control interventions. However, the persistent high number of cases in older children and adults highlights the need for strategies to identify locally effective control measures that target all age groups. PMID:23815862
Background The effect of integrating vector larval intervention on malaria transmission is unknown when insecticide-treated bed-net (ITN) coverage is very high, and the optimal indicator for intervention evaluation needs to be determined when transmission is low. Methods A post hoc assignment of intervention-control cluster design was used to assess the added effect of both indoor residual spraying (IRS) and Bacillus-based larvicides (Bti) in addition to ITN in the western Kenyan highlands in 2010 and 2011. Cross-sectional, mass parasite screenings, adult vector populations, and cohort of active case surveillance (ACS) were conducted before and after the intervention in three study sites with two- to three-paired intervention-control clusters at each site each year. The effect of larviciding, IRS, ITNs and other determinants of malaria risk was assessed by means of mixed estimating methods. Results Average ITN coverage increased from 41% in 2010 to 92% in 2011 in the study sites. IRS intervention had significant added impact on reducing vector density in 2010 but the impact was modest in 2011. The effect of IRS on reducing parasite prevalence was significant in 2011 but was seasonal specific in 2010. ITN was significantly associated with parasite densities in 2010 but IRS application was significantly correlated with reduced gametocyte density in 2011. IRS application reduced about half of the clinical malaria cases in 2010 and about one-third in 2011 compare to non-intervention areas. Conclusion Compared with a similar study conducted in 2005, the efficacy of the current integrated vector control with ITN, IRS, and Bti reduced three- to five-fold despite high ITN coverage, reflecting a modest added impact on malaria transmission. Additional strategies need to be developed to further reduce malaria transmission. PMID:23870708
The article analyses the evolution of knowledge and rationale of control of a special case of malaria transmission based on Bromelia-Kerteszia complex. Since bromeliaceae function as a 'host of the carrier' and were previously associated with natural forests, the elucidation of bromeliad malaria historically elicited controversies concerning the imputation of Kertesziae as transmitters as well as over control strategies directed to bromelia eradication (manual removal, herbicides and deforestation), use of insecticides and chemoprophylaxis. Established authority, disciplinary traditions, conceptual premises and contemporary criteria for validating knowledge in the field partly explain the long time gap since Adolpho Lutz announced at the beginning of the century the existence of a new mosquito and breeding site as responsible for a 'forest malaria' epidemic occurring at a high altitude. The article brings attention to how economic, political and institutional determinants played an important role in redefining studies that led both in Trinidad and Brazil to the recognition of the importance of kerteszia transmission, including urban areas, and establishing new approaches to its study, most relevant of all the concurrence of broad ecological research. The article then describes the Brazilian campaign strategies which showed significant short-term results but had to wait four decades to achieve the goal of eradication due to the peculiar characteristics of this pathogenic complex. Finally, it brings attention to the importance of encompassing social values and discourses, in this case, environmental preservation, to understanding historical trends of malaria control programs.
Wang, Shr-Jie; Lengeler, Christian; Smith, Thomas A; Vounatsou, Penelope; Cissé, Guéladio; Tanner, Marcel
Background Currently, there is a significant lack of knowledge concerning urban malaria patterns in general and in Abidjan in particular. The prevalence of malaria, its distribution in the city and the fractions of fevers attributable to malaria in the health facilities have not been previously investigated. Methods A health facility-based survey and health care system evaluation was carried out in a peripheral municipality of Abidjan (Yopougon) during the rainy season of 2002, applying a standardized Rapid Urban Malaria Appraisal (RUMA) methodology. Results According to national statistics, approximately 240,000 malaria cases (both clinical cases and laboratory confirmed cases) were reported by health facilities in the whole of Abidjan in 2001. They accounted for 40% of all consultations. In the health facilities of the Yopougon municipality, the malaria infection rates in fever cases for different age groups were 22.1% (under one year-olds), 42.8% (one to five years-olds), 42.0% (> five to 15 years-olds) and 26.8% (over 15 years-olds), while those in the control group were 13.0%. 26.7%, 21.8% and 14.6%, respectively. The fractions of malaria-attributable fever were 0.12, 0.22, 0.27 and 0.13 in the same age groups. Parasitaemia was homogenously detected in different areas of Yopougon. Among all children, 10.1% used a mosquito net (treated or not) the night before the survey and this was protective (OR = 0.52, 95% CI 0.29–0.97). Travel to rural areas within the last three months was frequent (31% of all respondents) and associated with a malaria infection (OR = 1.75, 95% CI 1.25–2.45). Conclusion Rapid urbanization has changed malaria epidemiology in Abidjan and endemicity was found to be moderate in Yopougon. Routine health statistics are not fully reliable to assess the burden of disease, and the low level of the fractions of malaria-attributable fevers indicated substantial over-treatment of malaria. PMID:16584575
Mahata, Khadak; Panday, Arnico; Rupakheti, Maheswar; Lawrence, Mark
Anthropogenic emissions of carbon dioxide and methane - key greenhouse gases (GHGs) - are primary causes of global warming and resultant impacts. The atmospheric warming is more pronounced and likely to cause more serious damage in vulnerable areas such as the Hindukush-Karakorum-Himalayan region (HKH). The HKH region is a data gap region according to the 5th Assessment report of the intergovernmental panel on climate change (IPCC). In order to understand the mixing ratios and variability of the key GHGs in the foothills of the Central Himalaya, we carried out continuous measurements of CO2, CH4, CO, and water vapor at Bode (an urban site in the Kathmandu valley, Nepal) for a year (March 2013 - Feb 2014), and again at Bode and at Chanban (a background outside the Valley) for 3 months (July 15 - Oct 3, 2015), with two state-of-the-art cavity ring-down instruments (Picarro G2401). The measurements were carried out as a part of the international air pollution measurement campaign: SusKat- ABC (Sustainable atmosphere for the Kathmandu Valley - Atmospheric Brown Clouds). The annual average CO2 and CH4 concentrations at Bode were 419 ± 24 and 2.192 ± 0.224 ppm, respectively, which are notably higher than those observed at the background site at Mauna Loa Observatory in the same period. The CO2concentration at Bode was high during the pre-monsoon period and low during the monsoon, while CH4 was high in winter and lower during the pre-monsoon period. The monthly CO2concentration was highest in April. Forest fires and agro-waste burning in the region, and the local emissions in the Kathmandu valley were the main sources of the high CO2 in the pre-monsoon period. CH4 showed a maximum in September due to additional emissions from paddy fields. Seasonally, winter has the highest CH4 concentration which is due to brick production, which is a seasonal activity, and other local sources combined with the shallow mixing layer height in winter. The diurnal pattern of CO2 and CH4
Snow, Robert W.; Amratia, Punam; Zamani, Ghasem; Mundia, Clara W.; Noor, Abdisalan M.; Memish, Ziad A.; Al Zahrani, Mohammad H.; Al Jasari, Adel; Fikri, Mahmoud; Atta, Hoda
The transmission of malaria across the Arabian Peninsula is governed by the diversity of dominant vectors and extreme aridity. It is likely that where malaria transmission was historically possible it was intense and led to a high disease burden. Here, we review the speed of elimination, approaches taken, define the shrinking map of risk since 1960 and discuss the threats posed to a malaria-free Arabian Peninsula using the archive material, case data and published works. From as early as the 1940s, attempts were made to eliminate malaria on the peninsula but were met with varying degrees of success through to the 1970s; however, these did result in a shrinking of the margins of malaria transmission across the peninsula. Epidemics in the 1990s galvanised national malaria control programmes to reinvigorate control efforts. Before the launch of the recent global ambition for malaria eradication, countries on the Arabian Peninsula launched a collaborative malaria-free initiative in 2005. This initiative led a further shrinking of the malaria risk map and today locally acquired clinical cases of malaria are reported only in Saudi Arabia and Yemen, with the latter contributing to over 98% of the clinical burden. PMID:23548086
Kolam, Joel; Inape, Kasis
Objectives This study was conducted to describe the regional malaria incidence in relation to the geographic and climatic conditions and describe the effect of altitude on the expansion of malaria over the last decade in Papua New Guinea. Methods Malaria incidence was estimated in five provinces from 1996 to 2008 using national health surveillance data. Time trend of malaria incidence was compared with rainfall and minimum/maximum temperature. In the Eastern Highland Province, time trend of malaria incidence over the study period was stratified by altitude. Spatio-temporal pattern of malaria was analyzed. Results Nationwide, malaria incidence was stationary. Regionally, the incidence increased markedly in the highland region (292.0/100000/yr, p =0.021), and remained stationary in the other regions. Seasonality of the malaria incidence was related with rainfall. Decreasing incidence of malaria was associated with decreasing rainfall in the southern coastal region, whereas it was not evident in the northern coastal region. In the Eastern Highland Province, malaria incidence increased in areas below 1700 m, with the rate of increase being steeper at higher altitudes. Conclusions Increasing trend of malaria incidence was prominent in the highland region of Papua New Guinea, while long-term trend was dependent upon baseline level of rainfall in coastal regions. PMID:26987606
Uchida, Masaki; Kishimoto, Ayaka; Muraoka, Hiroyuki; Nakatsubo, Takayuki; Kanda, Hiroshi; Koizumi, Hiroshi
We examined factors controlling temporal changes in net ecosystem production (NEP) in a high Arctic polar semi-desert ecosystem in the snow-free season. We examined the relationships between NEP and biotic and abiotic factors in a dominant plant community (Salix polaris-moss) in the Norwegian high Arctic. Just after snowmelt in early July, the ecosystem released CO(2) into the atmosphere. A few days after snowmelt, however, the ecosystem became a CO(2) sink as the leaves of S. polaris developed. Diurnal changes in NEP mirrored changes in light incidence (photosynthetic photon flux density, PPFD) in summer. NEP was significantly correlated with PPFD when S. polaris had fully developed leaves, i.e., high photosynthetic activity. In autumn, NEP values decreased as S. polaris underwent senescence. During this time, CO(2) was sometimes released into the atmosphere. In wet conditions, moss made a larger contribution to NEP. In fact, the water content of the moss regulated NEP during autumn. Our results indicate that the main factors controlling NEP in summer are coverage and growth of S. polaris, PPFD, and precipitation. In autumn, the main factor controlling NEP is moss water content.
Anvikar, Anupkumar R; Shah, Naman; Dhariwal, Akshay C; Sonal, Gagan Singh; Pradhan, Madan Mohan; Ghosh, Susanta K; Valecha, Neena
Historically, malaria in India was predominantly caused by Plasmodium vivax, accounting for 53% of the estimated cases. After the spread of drug-resistant Plasmodium falciparum in the 1990s, the prevalence of the two species remained equivalent at the national level for a decade. By 2014, the proportion of P. vivax has decreased to 34% nationally, but with high regional variation. In 2014, P. vivax accounted for around 380,000 malaria cases in India; almost a sixth of all P. vivax cases reported globally. Plasmodium vivax has remained resistant to control measures, particularly in urban areas. Urban malaria is predominantly caused by P. vivax and is subject to outbreaks, often associated with increased mortality, and triggered by bursts of migration and construction. The epidemiology of P. vivax varies substantially within India, including multiple relapse phenotypes with varying latencies between primary infection and relapse. Moreover, the hypnozoite reservoir maintains transmission potential and enables reestablishment of the parasite in areas in which it was thought eradicated. The burden of malaria in India is complex because of the highly variable malaria eco-epidemiological profiles, transmission factors, and the presence of multiple Plasmodium species and Anopheles vectors. This review of P. vivax malaria in India describes epidemiological trends with particular attention to four states: Gujarat, Karnataka, Haryana, and Odisha.
Anvikar, Anupkumar R.; Shah, Naman; Dhariwal, Akshay C.; Sonal, Gagan Singh; Pradhan, Madan Mohan; Ghosh, Susanta K.; Valecha, Neena
Historically, malaria in India was predominantly caused by Plasmodium vivax, accounting for 53% of the estimated cases. After the spread of drug-resistant Plasmodium falciparum in the 1990s, the prevalence of the two species remained equivalent at the national level for a decade. By 2014, the proportion of P. vivax has decreased to 34% nationally, but with high regional variation. In 2014, P. vivax accounted for around 380,000 malaria cases in India; almost a sixth of all P. vivax cases reported globally. Plasmodium vivax has remained resistant to control measures, particularly in urban areas. Urban malaria is predominantly caused by P. vivax and is subject to outbreaks, often associated with increased mortality, and triggered by bursts of migration and construction. The epidemiology of P. vivax varies substantially within India, including multiple relapse phenotypes with varying latencies between primary infection and relapse. Moreover, the hypnozoite reservoir maintains transmission potential and enables reestablishment of the parasite in areas in which it was thought eradicated. The burden of malaria in India is complex because of the highly variable malaria eco-epidemiological profiles, transmission factors, and the presence of multiple Plasmodium species and Anopheles vectors. This review of P. vivax malaria in India describes epidemiological trends with particular attention to four states: Gujarat, Karnataka, Haryana, and Odisha. PMID:27708188
Semenchuk, Philipp R.; Christiansen, Casper T.; Grogan, Paul; Elberling, Bo; Cooper, Elisabeth J.
Tundra soils store large amounts of carbon (C) that could be released through enhanced ecosystem respiration (ER) as the arctic warms. Over time, this may change the quantity and quality of available soil C pools, which in-turn may feedback and regulate ER responses to climate warming. Therefore, short-term increases in ER rates due to experimental warming may not be sustained over longer periods, as observed in other studies. One important aspect, which is often overlooked, is how climatic changes affecting ER in one season may carry-over and determine ER in following seasons. Using snow fences, we increased snow depth and thereby winter soil temperatures in a high-arctic site in Svalbard (78°N) and a low-arctic site in the Northwest Territories, Canada (64°N), for 5 and 9 years, respectively. Deepened snow enhanced winter ER while having negligible effect on growing-season soil temperatures and soil moisture. Growing-season ER at the high-arctic site was not affected by the snow treatment after 2 years. However, surprisingly, the deepened snow treatments significantly reduced growing-season ER rates after 5 years at the high-arctic site and after 8-9 years at the low-arctic site. We speculate that the reduction in ER rates, that became apparent only after several years of experimental manipulation, may, at least in part, be due to prolonged depletion of labile C substrate as a result of warmer soils over multiple cold seasons. Long-term changes in winter climate may therefore significantly influence annual net C balance not just because of increased wintertime C loss but also because of "legacy" effects on ER rates during the following growing seasons.
Lukianova-Hleb, Ekaterina Y.; Campbell, Kelly M.; Constantinou, Pamela E.; Braam, Janet; Olson, John S.; Ware, Russell E.; Sullivan, David S.; Lapotko, Dmitri
Successful diagnosis, screening, and elimination of malaria critically depend on rapid and sensitive detection of this dangerous infection, preferably transdermally and without sophisticated reagents or blood drawing. Such diagnostic methods are not currently available. Here we show that the high optical absorbance and nanosize of endogenous heme nanoparticles called hemozoin, a unique component of all blood-stage malaria parasites, generate a transient vapor nanobubble around hemozoin in response to a short and safe near-infrared picosecond laser pulse. The acoustic signals of these malaria-specific nanobubbles provided the first transdermal non-invasive and rapid detection of a malaria infection as low as 0.00034% in animals without using any reagents or drawing blood. These on-demand transient events have no analogs among current malaria markers and probes, can detect and screen malaria in seconds and can be realized as a compact, easy to use, inexpensive and safe field technology.
Background Over the past 20 years, numerous studies have investigated the ecology and behaviour of malaria vectors and Plasmodium falciparum malaria transmission on the coast of Kenya. Substantial progress has been made to control vector populations and reduce high malaria prevalence and severe disease. The goal of this paper was to examine trends over the past 20 years in Anopheles species composition, density, blood-feeding behaviour, and P. falciparum sporozoite transmission along the coast of Kenya. Methods Using data collected from 1990 to 2010, vector density, species composition, blood-feeding patterns, and malaria transmission intensity was examined along the Kenyan coast. Mosquitoes were identified to species, based on morphological characteristics and DNA extracted from Anopheles gambiae for amplification. Using negative binomial generalized estimating equations, mosquito abundance over the period were modelled while adjusting for season. A multiple logistic regression model was used to analyse the sporozoite rates. Results Results show that in some areas along the Kenyan coast, Anopheles arabiensis and Anopheles merus have replaced An. gambiae sensu stricto (s.s.) and Anopheles funestus as the major mosquito species. Further, there has been a shift from human to animal feeding for both An. gambiae sensu lato (s.l.) (99% to 16%) and An. funestus (100% to 3%), and P. falciparum sporozoite rates have significantly declined over the last 20 years, with the lowest sporozoite rates being observed in 2007 (0.19%) and 2008 (0.34%). There has been, on average, a significant reduction in the abundance of An. gambiae s.l. over the years (IRR = 0.94, 95% CI 0.90–0.98), with the density standing at low levels of an average 0.006 mosquitoes/house in the year 2010. Conclusion Reductions in the densities of the major malaria vectors and a shift from human to animal feeding have contributed to the decreased burden of malaria along the Kenyan coast. Vector species
Valkiūnas, Gediminas; Iezhova, Tatjana A; Loiseau, Claire; Smith, Thomas B; Sehgal, Ravinder N M
Blood samples from 655 passerine birds were collected in rainforests of Ghana and Cameroon and examined both by microscopy and polymerase chain reaction (PCR)-based techniques. The overall prevalence of Plasmodium spp. was 46.6%, as determined by combining the results of both these diagnostic methods. In comparison to PCR-based diagnostics, microscopic examination of blood films was more sensitive in determining simultaneous infection of Plasmodium spp., but both detection methods showed similar trends of prevalence of malaria parasites in the same study sites. Plasmodium (Novyella) lucens n. sp., Plasmodium (Novyella) multivacuolaris n. sp. and Plasmodium (Novyella) parahexamerium n. sp. were found in the olive sunbird Cyanomitra olivacea (Nectariniidae), yellow-whiskered greenbul Andropadus latirostris (Picnonotidae), and white-tailed alethe Alethe diademata (Turdidae), respectively. These parasites are described based on the morphology of their blood stages and a segment of the mitochondrial cytochrome b (cyt b) gene, which can be used for molecular identification and diagnosis of these species. Illustrations of blood stages of new species are given, and phylogenetic analysis identifies DNA lineages closely related to these parasites. Malaria parasites of the subgenus Novyella with small erythrocytic meronts clearly predominate in African passerines. It is probable that the development of such meronts is a characteristic feature of evolution of Plasmodium spp. in African rainforest birds. Subgeneric taxonomy of avian Plasmodium spp. is discussed based on the recent molecular phylogenies of these parasites. It is concluded that a multi-genome phylogeny is needed before revising the current subgeneric classification of Plasmodium. We supported a hypothesis by Hellgren, Krizanauskiene, Valkiūnas, Bensch (J Parasitol 93:889-896, 2007), according to which, haemosporidian species with a genetic differentiation of over 5% in mitochondrial cyt b gene are expected to be
Sharma, V P; Mehrotra, K N
In 1953, the Indian National Malaria Control Programme (NMCP) was started. Encouraged by the results, and the fact that insecticide resistance in vector species may evolve and become an obstacle, in 1958 a control programme was converted to the National Malaria Eradication Programme (NMEP). By 1964, malaria was eradicated from 88% of the area and it was in the advanced stage of spraying in the remaining parts. At that time, focal outbreaks that occurred in 1965 and increased in later years, could not be contained due to the shortages of DDT. As a result, large areas in consolidation and maintenance phases were reverted to the attack phase. Besides, the infrastructure in general health services was not adequate and mature enough to take up surveillance and vigilance. This produced a large number of secondary cases due to the re-introduction and relapse of malaria. Added to this was the problem of urban malaria, the control of which was the responsibility of local bodies. Malaria cases increased in towns, and started diffusing to the rural areas, due to inadequate staff and the shortages of malarial larvicidal oil (MLO). Later, it turned out, that while it was technically feasible to eradicate malaria from 91% of the population, the strategy of indoor spraying of DDT to interrupt transmission did not succeed in 9.0% of the population, despite more than 12-14 years of regular spraying. During the years of resurgence, there was no research support to the programme, so that technical problems were not properly appreciated, understood and tackled. The reservoir of parasites that were present throughout the country started multiplying and spreading to newer areas due to the presence of vectors in high densities. Thus malaria resurged and re-established itself even in areas that were at one time freed from the disease. The analysis of the pattern of malaria resurgence revealed that malaria outbreaks preceded the true problem of insecticide resistance. It is noteworthy to
McGready, Rose; Boel, Machteld; Rijken, Marcus J.; Ashley, Elizabeth A.; Cho, Thein; Moo, Oh; Paw, Moo Koh; Pimanpanarak, Mupawjay; Hkirijareon, Lily; Carrara, Verena I.; Lwin, Khin Maung; Phyo, Aung Pyae; Turner, Claudia; Chu, Cindy S.; van Vugt, Michele; Price, Richard N.; Luxemburger, Christine; ter Kuile, Feiko O.; Tan, Saw Oo; Proux, Stephane; Singhasivanon, Pratap; White, Nicholas J.; Nosten, François H.
Introduction Maternal mortality is high in developing countries, but there are few data in high-risk groups such as migrants and refugees in malaria-endemic areas. Trends in maternal mortality were followed over 25 years in antenatal clinics prospectively established in an area with low seasonal transmission on the north-western border of Thailand. Methods and Findings All medical records from women who attended the Shoklo Malaria Research Unit antenatal clinics from 12th May 1986 to 31st December 2010 were reviewed, and maternal death records were analyzed for causality. There were 71 pregnancy-related deaths recorded amongst 50,981 women who attended antenatal care at least once. Three were suicide and excluded from the analysis as incidental deaths. The estimated maternal mortality ratio (MMR) overall was 184 (95%CI 150–230) per 100,000 live births. In camps for displaced persons there has been a six-fold decline in the MMR from 499 (95%CI 200–780) in 1986–90 to 79 (40–170) in 2006–10, p<0.05. In migrants from adjacent Myanmar the decline in MMR was less significant: 588 (100–3260) to 252 (150–430) from 1996–2000 to 2006–2010. Mortality from P.falciparum malaria in pregnancy dropped sharply with the introduction of systematic screening and treatment and continued to decline with the reduction in the incidence of malaria in the communities. P.vivax was not a cause of maternal death in this population. Infection (non-puerperal sepsis and P.falciparum malaria) accounted for 39.7 (27/68) % of all deaths. Conclusions Frequent antenatal clinic screening allows early detection and treatment of falciparum malaria and substantially reduces maternal mortality from P.falciparum malaria. No significant decline has been observed in deaths from sepsis or other causes in refugee and migrant women on the Thai–Myanmar border. PMID:22815732
Foster, J.T.; Woodworth, B.L.; Eggert, L.E.; Hart, P.J.; Palmer, D.; Duffy, D.C.; Fleischer, R.C.
Infectious diseases now threaten wildlife populations worldwide but population recovery following local extinction has rarely been observed. In such a case, do resistant individuals recolonize from a central remnant population, or do they spread from small, perhaps overlooked, populations of resistant individuals? Introduced avian malaria (Plasmodium relictum) has devastated low-elevation populations of native birds in Hawaii, but at least one species (Hawaii amakihi, Hemignathus virens) that was greatly reduced at elevations below about 1000 m tolerates malaria and has initiated a remarkable and rapid recovery. We assessed mitochondrial and nuclear DNA markers from amakihi and two other Hawaiian honeycreepers, apapane (Himatione sanguinea) and iiwi (Vestiaria coccinea), at nine primary study sites from 2001 to 2003 to determine the source of re-establishing birds. In addition, we obtained sequences from tissue from amakihi museum study skins (1898 and 1948-49) to assess temporal changes in allele distributions. We found that amakihi in lowland areas are, and have historically been, differentiated from birds at high elevations and had unique alleles retained through time; that is, their genetic signature was not a subset of the genetic variation at higher elevations. We suggest that high disease pressure rapidly selected for resistance to malaria at low elevation, leaving small pockets of resistant birds, and this resistance spread outward from the scattered remnant populations. Low-elevation amakihi are currently isolated from higher elevations (> 1000 m) where disease emergence and transmission rates appear to vary seasonally and annually. In contrast to results from amakihi, no genetic differentiation between elevations was found in apapane and iiwi, indicating that slight variation in genetic or life-history attributes can determine disease resistance and population recovery. Determining the conditions that allow for the development of resistance to disease is
Jakobsen, Palle Høy; McKay, Veronica; N’Jie, Ramou; Olaleye, Ben O.; D’Alessandro, Umberto; Zhang, Gui-Hang; Eggelte, Teunis A.; Koch, Claus; Greenwood, Brian M.
Healthy Gambian children, children with clinical Plasmodium falciparum malaria, and children with asymptomatic P. falciparum infections were studied to investigate whether antitoxic activities may contribute to protection against malarial symptoms. Markers of inflammatory reactions, soluble tumor necrosis factor receptor I, and C-reactive protein were found in high concentrations in children with symptomatic P. falciparum malaria compared with levels in children with asymptomatic P. falciparum infections or in healthy children, indicating that inflammatory reactions are induced only in children with clinical symptoms. Concentrations of soluble tumor necrosis factor receptor I and C-reactive protein were associated with levels of parasitemia. We detected antitoxic activities in sera as measured by their capacity to block toxin-induced Limulus amoebocyte lysate (LAL) activation. Symptomatic children had decreased capacity to block induction of LAL activation by P. falciparum exoantigen. The decreased blocking activity was restored in the following dry season, when the children had no clinical malaria. Symptomatic children also had the highest immunoglobulin G (IgG) reactivities to conserved P. falciparum erythrocyte membrane protein 1 and “Pfalhesin” (band #3) peptides, indicating that such IgG antibodies are stimulated by acute disease but are lost rapidly after the disease episode. Half of the children with symptomatic infections had low levels of haptoglobin, suggesting that these children had chronic P. falciparum infections which may have caused symptoms previously. Only a few of the children with asymptomatic P. falciparum infections had high parasite counts, and antitoxic immunity in the absence of antiparasite immunity appears to be rare among children in this community. PMID:9529094
Rieck, Jan K.; Böning, Claus W.; Greatbatch, Richard J.; Scheinert, Markus
A global ocean model with 1/12° horizontal resolution is used to assess the seasonal cycle of surface eddy kinetic energy (EKE). The model reproduces the salient features of the observed mean surface EKE, including amplitude and phase of its seasonal cycle in most parts of the ocean. In all subtropical gyres of the Pacific and Atlantic, EKE peaks in summer down to a depth of ˜350 m, below which the seasonal cycle is weak. Investigation of the possible driving mechanisms reveals the seasonal changes in the thermal interactions with the atmosphere to be the most likely cause of the summer maximum of EKE. The development of the seasonal thermocline in spring and summer is accompanied by stronger mesoscale variations in the horizontal temperature gradients near the surface which corresponds, by thermal wind balance, to an intensification of mesoscale velocity anomalies toward the surface.
Vergara, Oscar; Dewitte, Boris; Montes, Ivonne; Garçon, Veronique; Ramos, Marcel; Paulmier, Aurélien; Pizarro, Oscar
In addition to being one of the most productive upwelling systems, the oceanic region off Peru is embedded in one of the most extensive oxygen minimum zones (OMZs) of the world ocean. The dynamics of the OMZ off Peru remain uncertain, partly due to the scarcity of data and to the ubiquitous role of mesoscale activity on the circulation and biogeochemistry. Here we use a high-resolution coupled physical/biogeochemical model simulation to investigate the seasonal variability of the OMZ off Peru. The focus is on characterizing the seasonal cycle in dissolved O2 (DO) eddy flux at the OMZ boundaries, including the coastal domain, viewed here as the eastern boundary of the OMZ, considering that the mean DO eddy flux in these zones has a significant contribution to the total DO flux. The results indicate that the seasonal variations of the OMZ can be interpreted as resulting from the seasonal modulation of the mesoscale activity. Along the coast, despite the increased seasonal low DO water upwelling, the DO peaks homogeneously over the water column and within the Peru Undercurrent (PUC) in austral winter, which results from mixing associated with the increase in both the intraseasonal wind variability and baroclinic instability of the PUC. The coastal ocean acts therefore as a source of DO in austral winter for the OMZ core, through eddy-induced offshore transport that is also shown to peak in austral winter. In the open ocean, the OMZ can be divided vertically into two zones: an upper zone above 400 m, where the mean DO eddy flux is larger on average than the mean seasonal DO flux and varies seasonally, and a lower part, where the mean seasonal DO flux exhibits vertical-zonal propagating features that share similar characteristics than those of the energy flux associated with the annual extratropical Rossby waves. At the OMZ meridional boundaries where the mean DO eddy flux is large, the DO eddy flux has also a marked seasonal cycle that peaks in austral winter (spring
Narang, Vikram; Sood, Neena; Garg, Bhavna; Gupta, Vikram Kumar
Background Haematological abnormalities are common in acute febrile tropical illnesses. Malaria is a major health problem in tropics. In endemic areas especially in the post monsoon season, it is not practical to manually screen all peripheral blood films (PBF) for malarial parasite. Automated analysers offer rapid, sensitive and cost effective screening of all samples. Aim The study was done to evaluate the usefulness of automated cell counters analysing their histograms, scatter-grams and the flaggings generated in malaria positive and negative cases. The comparison of other haematological parameters were also studied which could help to identify malaria parasite in peripheral blood smear. Materials and Methods The blood samples were analysed using Beckman coulter LH-750. The abnormal scatter grams and additional peaks in WBC histograms were observed diligently & compared with normal controls. Haematological abnormalities were also evaluated. Statistical Analysis Statistical analysis was done by using software Epi-Info version 7.1.4 freely available from CDC website. Fisher exact test was applied to calculate the p-value and value < 0.05 was considered as significant. Final identification of malarial parasite species was done independently by peripheral blood smear examination by two pathologists. Results Of all the 200 cases evaluated abnormal scatter grams were observed in all the cases of malaria while abnormal WBC histogram peaks were noted in 96% cases demonstrating a peak at the threshold of the histogram. The difference between number of slides positive for abnormal WBC scatter gram and abnormal WBC histogram peaks were statistically highly significant (p=0.007). So abnormal WBC scatter gram can better give idea of malarial parasite presence. Of the haematological parameters thrombocytopenia (92% cases) emerged as the strongest predictor of malaria. Conclusion It is recommended for haematopathologists to review the haematological data and the scatter plots
Rojo-Marcos, Gerardo; Cuadros-González, Juan
Malaria is life threatening and requires urgent diagnosis and treatment. Incidence and mortality are being reduced in endemic areas. Clinical features are unspecific so in imported cases it is vital the history of staying in a malarious area. The first line treatments for Plasmodium falciparum are artemisinin combination therapies, chloroquine in most non-falciparum and intravenous artesunate if any severity criteria. Human infections with intestinal protozoa are distributed worldwide with a high global morbid-mortality. They cause diarrhea and sometimes invasive disease, although most are asymptomatic. In our environment populations at higher risk are children, including adopted abroad, immune-suppressed, travelers, immigrants, people in contact with animals or who engage in oral-anal sex. Diagnostic microscopic examination has low sensitivity improving with antigen detection or molecular methods. Antiparasitic resistances are emerging lately.
Maheskumar, R. S.; Narkhedkar, S. G.; Morwal, S. B.; Padmakumari, B.; Kothawale, D. R.; Joshi, R. R.; Deshpande, C. G.; Bhalwankar, R. V.; Kulkarni, J. R.
The mechanism responsible for high rainfall over the Indian west coast region has been investigated by studying dynamical, thermodynamical and microphysical processes over the region for the monsoon season of 2009. The European Centre for Medium-Range Weather Forecasts wind and NCEP flux data have been used to study the large scale dynamical parameters. The moist adiabatic and multi-level inversion stratifications are found to exist during the high and low rainfall spells, respectively. In the moist adiabatic stratification regime, shallow and deep convective clouds are found coexisting. The Cloud Aerosol Interaction and Precipitation Enhancement EXperiment aircraft data showed cloud updraft spectrum ranging from 1 to 10 m s-1 having modal speed 1-2.5 m s-1. The low updrafts rates provide sufficient time required for warm rain processes to produce rainfall from shallow clouds. The low cloud liquid water is observed above the freezing level indicating efficient warm rain process. The updrafts at the high spectrum end go above freezing level to generate ice particles produced due to mixed-phase rainfall process from deep convective clouds. With aging, deep convection gets transformed into stratiform type, which has been inferred through the vertical distribution of the large scale omega and heating fields. The stratiform heating, high latent heat flux, strong wind shear in the lower and middle tropospheric levels and low level convergence support the sustenance of convection for longer time to produce high rainfall spell. The advection of warm dry air in the middle tropospheric regions inhibits the convection and produce low rainfall spell. The mechanisms producing these spells have been summarized with the block diagram.
Yusuf, Farah Hafiz; Hafiz, Muhammad Yusuf; Shoaib, Maria; Ahmed, Syed Ahsanuddin
Cerebral malaria is a medical emergency. All patients with Plasmodium falciparum malaria with neurologic manifestations of any degree should be urgently treated as cases of cerebral malaria. Pathogenesis of cerebral malaria is due to damaged vascular endothelium by parasite sequestration, inflammatory cytokine production and vascular leakage, which result in brain hypoxia, as indicated by increased lactate and alanine concentrations. The levels of the biomarkers’ histidine-rich protein II, angiopoietin-Tie-2 system and plasma osteoprotegrin serve as diagnostic and prognostic markers. Brain imaging may show neuropathology around the caudate and putamen. Mortality is high and patients who survive sustain brain injury which manifests as long-term neurocognitive impairments. PMID:28203097
Grilo, M L; Vanstreels, R E T; Wallace, R; García-Párraga, D; Braga, É M; Chitty, J; Catão-Dias, J L; Madeira de Carvalho, L M
Avian malaria is a mosquito-borne disease caused by protozoans of the genus Plasmodium, and it is considered one of the most important causes of morbidity and mortality in captive penguins, both in zoological gardens and rehabilitation centres. Penguins are known to be highly susceptible to this disease, and outbreaks have been associated with mortality as high as 50-80% of affected captive populations within a few weeks. The disease has also been reported in wild penguin populations, however, its impacts on the health and fitness of penguins in the wild is not clear. This review provides an overview of the aetiology, life cycle and epidemiology of avian malaria, and provides details on the strategies that can be employed for the diagnostic, treatment and prevention of this disease in captive penguins, discussing possible directions for future research.
Marcaccio, J. V.; Markle, C. E.; Chow-Fraser, P.
With recent advances in technology, personal aerial imagery acquired with unmanned aerial vehicles (UAVs) has transformed the way ecologists can map seasonal changes in wetland habitat. Here, we use a multi-rotor (consumer quad-copter, the DJI Phantom 2 Vision+) UAV to acquire a high-resolution (< 8 cm) composite photo of a coastal wetland in summer 2014. Using validation data collected in the field, we determine if a UAV image and SWOOP (Southwestern Ontario Orthoimagery Project) image (collected in spring 2010) differ in their classification of type of dominant vegetation type and percent cover of three plant classes: submerged aquatic vegetation, floating aquatic vegetation, and emergent vegetation. The UAV imagery was more accurate than available SWOOP imagery for mapping percent cover of submergent and floating vegetation categories, but both were able to accurately determine the dominant vegetation type and percent cover of emergent vegetation. Our results underscore the value and potential for affordable UAVs (complete quad-copter system < 3,000 CAD) to revolutionize the way ecologists obtain imagery and conduct field research. In Canada, new UAV regulations make this an easy and affordable way to obtain multiple high-resolution images of small (< 1.0 km2) wetlands, or portions of larger wetlands throughout a year.
Background Knowledge on the temporal dynamics of host/vector/parasite interactions is a pre-requisite to further address relevant questions in the fields of epidemiology and evolutionary ecology of infectious diseases. In studies of avian malaria, the natural history of Plasmodium parasites with their natural mosquito vectors, however, is mostly unknown. Methods Using artificial water containers placed in the field, we monitored the relative abundance of parous females of Culex pipiens mosquitoes during two years (2010–2011), in a population in western Switzerland. Additionally, we used molecular tools to examine changes in avian malaria prevalence and Plasmodium lineage composition in female C. pipiens caught throughout one field season (April-August) in 2011. Results C. pipiens relative abundance varied both between years and months, and was associated with temperature fluctuations. Total Plasmodium prevalence was high and increased from spring to summer months (13.1-20.3%). The Plasmodium community was composed of seven different lineages including P. relictum (SGS1, GRW11 and PADOM02 lineages), P. vaughani (lineage SYAT05) and other Plasmodium spp. (AFTRU5, PADOM1, COLL1). The most prevalent lineages, P. vaughani (lineage SYAT05) and P. relictum (lineage SGS1), were consistently found between years, although they had antagonistic dominance patterns during the season survey. Conclusions Our results suggest that the time window of analysis is critical in evaluating changes in the community of avian malaria lineages infecting mosquitoes. The potential determinants of the observed changes as well as their implications for future prospects on avian malaria are discussed. PMID:24499594
Oliva, Marc; Gómez-Ortiz, Antonio; Salvador-Franch, Ferran; Salvà-Catarineu, Montserrat; Palacios, David; Tanarro, Luis Miguel; Ramos, Miguel
Sierra Nevada, Southern Spain (37°S, 3°W), is the massif including the southernmost permafrost remnants in Europe. Over the last decades the distribution of permafrost in this massif has been examined through a combined approach including geomorphological, geophysical and monitoring studies. The purpose of this communication is to summarize all the studies relating to soil thermal regime in the high lands of Sierra Nevada. A 114.5 m deep borehole was drilled in 2000 in the Veleta summit (3380 m) in order to monitor soil temperatures in the summits of the massif. No permafrost regime was detected, with average temperatures stabilizing at 20 m depth at 2 °C. Seasonal frost conditions were also detected in periglacial landforms such as solifluction lobes and sorted-circles. In the Rio Seco cirque the mean annual temperatures in a solifluction lobe located in a southern glacial cirque of the massif (3005 m) were 3.9 °C at 1 m depth between 2006 and 2012; in the north-exposed San Juan valley, soil temperatures in another solifluction landform (2864 m) were 3.9 °C at 1 m depth between 2003 and 2012. In a sorted-circle located in the high plateau of Cerro de los Machos (3297 m) soil temperatures recorded an average of 1.7 °C at 50 cm depth between 2003 and 2011. The only place where temperatures were permanently negative was inside of the only active rock glacier distributed in the Veleta cirque, on the northern slope of the Veleta peak. Here, the remnants of a small glacier that existed during the Little Ice Age (LIA) are still present in the form of buried ice and permafrost buried under the boulders of this rock glacier. Temperatures averaged 0.2 °C at 1 m depth between 2006 and 2013, with permanently negative temperatures below this level until, at least, 10 m depth. Consequently, seasonal frost is widespread nowadays in most of the Sierra Nevada, with permafrost conditions strongly conditioned by the geomorphological setting and the recent environmental
Sutherland, Colin J; Babiker, Hamza; Mackinnon, Margaret J; Ranford-Cartwright, Lisa; El Sayed, Badria Babiker
Artemisinin-based combination therapy is exerting novel selective pressure upon populations of Plasmodium falciparum across Africa. Levels of resistance to non-artemisinin partner drugs differ among parasite populations, and so the artemisinins are not uniformly protected from developing resistance, already present in South East Asia. Here, we consider strategies for prolonging the period of high level efficacy of combination therapy for two particular endemicities common in Africa. Under high intensity transmission, two alternating first-line combinations, ideally with antagonistic selective effects on the parasite genome, are advocated for paediatric malaria cases. This leaves second-line and other therapies for adult cases, and for intermittent preventive therapy. The drug portfolio would be selected to protect the 'premier' combination regimen from selection for resistance, while maximising impact on severe disease and mortality in children. In endemic areas subject to low, seasonal transmission of Plasmodium falciparum, such a strategy may deliver little benefit, as children represent a minority of cases. Nevertheless, the deployment of other drug-based interventions in low transmission and highly seasonal areas, such as mass drug administration aimed to interrupt malaria transmission, or intermittent preventive therapy, does provide an opportunity to diversify drug pressure. We thus propose an integrated approach to drug deployment, which minimises direct selective pressure on parasite populations from any one drug component. This approach is suitable for qualitatively and quantitatively different burdens of malaria, and should be supported by a programme of routine surveillance for emerging resistance.
Ouattara, Amed; Barry, Alyssa E.; Dutta, Sheetij; Remarque, Edmond J.; Beeson, James G.; Plowe, Christopher V.
Prospects for malaria eradication will be greatly enhanced by an effective vaccine, but parasite genetic diversity poses a major impediment to malaria vaccine efficacy. In recent pre-clinical and field trials, vaccines based on polymorphic Plasmodium falciparum antigens have shown efficacy only against homologous strains, raising the specter of allele-specific immunity such as that which plagues vaccines against influenza and HIV. The most advanced malaria vaccine, RTS,S, targets relatively conserved epitopes on the P. falciparum circumsporozoite protein. After more than 40 years of development and testing, RTS,S, has shown significant but modest efficacy against clinical malaria in phase 2 and 3 trials. Ongoing phase 2 studies of an irradiated sporozoite vaccine will ascertain whether the full protection against homologous experimental malaria challenge conferred by high doses of a whole organism vaccine can provide protection against diverse strains in the field. Here we review and evaluate approaches being taken to design broadly cross-protective malaria vaccines. PMID:26475447
Karaman, Ulkü; Atambay, Metin; Yaşar, Safa; Colak, Cemil; Miman, Ozlem; Daldal, Nilgün
Malaria can be seen in every region inhabited by human blood-sucking Anopheles and species of disease-causing Plasmodium. Since the region is on the crossroads of other cities where malaria is more widespread and it has a population of seasonal workers and an increasing number of tourists during the summer, additional imported cases may also be detected in the Malatya region. The aim of this study was to determine the state of malaria for the past seven years in Malatya. According to the records of the Malaria Control Unit of the Health Directorate of the Malatya province, 189 positive patients were reported during the seven years from 1999-2005. Of these cases, 186 (98.4%) were P. vivax, while 3 (1.6%) were imported cases of P. falciparum malaria. The rate of positivity was found to be 58.2% in male patients and 41.8% in female patients. Consequently, malaria can be said to persist as a health problem in Malatya region. It was concluded that people in the region should be informed about malaria and the ways to protect themselves.
Spicer, Timothy; Fernandez-Vega, Virneliz; Chase, Peter; Scampavia, Louis; To, Joyce; Dalton, John P; Da Silva, Fabio L; Skinner-Adams, Tina S; Gardiner, Donald L; Trenholme, Katharine R; Brown, Christopher L; Ghosh, Partha; Porubsky, Patrick; Wang, Jenna L; Whipple, David A; Schoenen, Frank J; Hodder, Peter
The target of this study, the PfM18 aspartyl aminopeptidase (PfM18AAP), is the only AAP present in the genome of the malaria parasite Plasmodium falciparum. PfM18AAP is a metallo-exopeptidase that exclusively cleaves N-terminal acidic amino acids glutamate and aspartate. It is expressed in parasite cytoplasm and may function in concert with other aminopeptidases in protein degradation, of, for example, hemoglobin. Previous antisense knockdown experiments identified a lethal phenotype associated with PfM18AAP, suggesting that it is a valid target for new antimalaria therapies. To identify inhibitors of PfM18AAP function, a fluorescence enzymatic assay was developed using recombinant PfM18AAP enzyme and a fluorogenic peptide substrate (H-Glu-NHMec). This was screened against the Molecular Libraries Probe Production Centers Network collection of ~292,000 compounds (the Molecular Libraries Small Molecule Repository). A cathepsin L1 (CTSL1) enzyme-based assay was developed and used as a counter screen to identify compounds with nonspecific activity. Enzymology and phenotypic assays were used to determine mechanism of action and efficacy of selective and potent compounds identified from high-throughput screening. Two structurally related compounds, CID 6852389 and CID 23724194, yielded micromolar potency and were inactive in CTSL1 titration experiments (IC50>59.6 µM). As measured by the K(i) assay, both compounds demonstrated micromolar noncompetitive inhibition in the PfM18AAP enzyme assay. Both CID 6852389 and CID 23724194 demonstrated potency in malaria growth assays (IC504 µM and 1.3 µM, respectively).
Wildling, E; Winkler, S; Kremsner, P G; Brandts, C; Jenne, L; Wernsdorfer, W H
In the course of epidemiological and immunological baseline studies parasitological surveys were conducted, in 1992, in three localities situated in our near rain forest in the area of Lambaréné, Gabon, western Central Africa. Anopheles gambiae s.s. and A. funestus are considered to be the main vectors of malaria. The three localities represent strata with obvious differences in the intensity of malaria transmission. The lowest parasite rates were recorded in the village around the Albert-Schweitzer-Hospital where environmental sanitation and easy access to diagnostic and therapeutic facilities afford a fair measure of malaria control. The villages of Bellevue and Tchad show a much higher prevalence of Plasmodium falciparum, followed by P. malariae and P. ovale. In all three villages parasite rates and geometric mean parasite densities of P. falciparum showed the age pattern typical for areas with stable, hyperendemic malaria. Analysis by season showed the period of the long rains to be the epidemiologically calmest while the dry season and even more the short rainy season produced an increase of parasite rates and densities. In Tchad, the most affected of the three villages, the parasite rates in female adults were significantly lower than in male adults. This was accompanied by lower parasite densities in female adults.
Yapabandara, A M G M; Curtis, C F
An evaluation of pyriproxyfen as a larval control agent with the aim of reducing malaria vector populations and incidence of malaria was conducted in 12 villages in an irrigated settlement scheme in the dry zone of central Sri Lanka. In these villages, there are many pools in the beds of rivers, streams, and irrigation ditches during the dry season of the year. These are the major breeding places of the malaria vectors Anopheles culicifacies and An. subpictus. Collections of adult mosquitoes were carried out by using standard methods and parasitological data were collected by daily malaria clinics set up for the project and through the 2 government hospitals. All villages in the study area were under residual house spraying with lambdacyhalothrin water-dispersible powder. Using the 1st year's baseline data collection, the villages were stratified into 6 villages with high malaria incidence and 6 villages with low incidence. Within each group, 3 villages were randomly assigned for larval control by treating all the pools in the beds of rivers, streams, and irrigation ditches and agricultural wells with a granular formulation of the insect growth regulator pyriproxyfen at the rate of 0.01 mg active ingredient/liter. The field bioassays indicated that a single treatment of pyriproxyfen effectively inhibited the emergence of adult mosquitoes in the riverbed pools for a period of 190 days. The treatment caused significant reduction of the adult populations of An. culicifacies (78%) and An. subpictus (72%). Similarly, incidence of malaria was reduced in the treatment villages by about 70% (95% confidence interval 58-78%) compared with the controls. The conclusion is made that pyriproxyfen can be a very effective means of malaria control if all possible vector breeding places in the area can be located.
Pope, K O; Rejmankova, E; Savage, H M; Arredondo-Jimenez, J I; Rodriguez, M H; Roberts, D R
Malaria, transmitted by anopheline mosquitoes, remains a serious health problem in the tropics. Most malaria eradication efforts focus on control of anopheline vectors. These efforts include the NASA Di-Mod project, whose current goal is to integrate remote sensing, geographic information systems (GIS), and field research to predict anopheline mosquito population dynamics in the Pacific coastal plain of Chiapas, Mexico. Field studies demonstrate that high larval production of Anopheles albimanus, the principal malaria vector in the plain, can be linked to a small number of larval habitat-types, determined by larval sampling and cluster analysis of wetlands in the coastal plain. Analysis of wet and dry season Landsat Thematic Mapper (TM) satellite imagery identified 16 land cover units within an 185-km2 study area in the coastal zone. A hierarchical approach was used to link the larval habitat-types with the larger land cover units and make predictions of potential and actual low, medium, and high anopheline production. The TM-based map and GIS techniques were then used to predict differences in anopheline production at two villages, La Victoria and Efrain Gutierrez. La Victoria was predicted to have much higher Anopheles albimanus production, based upon a 2-10 times greater extent of medium- and high-producing land cover units in its vicinity. This difference between villages was independently supported by sampling (with light traps) of adults, which were 5-10 times more abundant in La Victoria.
Ishii, Toshiaki; Yoshizawa, Sadako; Miyazaki, Taito; Sano, Masanari; Takasaki, Tomohiko; Tateda, Kazuhiro; Morita, Toshisuke
There are three major differential diagnosis of febrile patients with history of travels to the tropical countries i.e., malaria, typhoid fever and dengue fever. Diagnosis of malaria patients undergoes sometimes arduous process due to the variable skills of laboratory technician, and more convenient method is warranted. Immunochromatography (IC) method is simple method and recently used for diagnosis of several infectious diseases. Here, we reported usefulness of IC method for malaria and dengue fever diagnosis. Forty-seven samples from 46 patients were retrospectively analyzed by both malaria IC method and microscopic examination. Furthermore, three patients were undergone dengue IC method followed by PCR and antibody examination (ELISA) if the results were positive. Several factors such as rheumatoid factor (RF) are known to affect the results of IC method. We also checked malaria and dengue IC method using serum known to be high RF results without malaria infection. Totally six patients were diagnosed as malaria i.e., 1 vivax malaria and 5 falciparum malaria. Sensitivity and specificity of the malaria IC method were excellent, 100% and 97.6%, respectively. Among three patients, one patient revealed false-negative results of dengue IC method, however, results of the other two patients revealed good correlation between IC method and PCR/ELISA results. Among four RF positive serums, 2 malaria IC method and 4 dengue IC method revealed false-positive results. In summary, IC method for malaria and dengue fever might be quick and convenient method and considered to be used as an adjunctive diagnostic tool.
Laporta, Gabriel Zorello; de Prado, Paulo Inácio Knegt Lopez; Kraenkel, Roberto André; Coutinho, Renato Mendes; Sallum, Maria Anice Mureb
Background Plasmodium vivax is a widely distributed, neglected parasite that can cause malaria and death in tropical areas. It is associated with an estimated 80–300 million cases of malaria worldwide. Brazilian tropical rain forests encompass host- and vector-rich communities, in which two hypothetical mechanisms could play a role in the dynamics of malaria transmission. The first mechanism is the dilution effect caused by presence of wild warm-blooded animals, which can act as dead-end hosts to Plasmodium parasites. The second is diffuse mosquito vector competition, in which vector and non-vector mosquito species compete for blood feeding upon a defensive host. Considering that the World Health Organization Malaria Eradication Research Agenda calls for novel strategies to eliminate malaria transmission locally, we used mathematical modeling to assess those two mechanisms in a pristine tropical rain forest, where the primary vector is present but malaria is absent. Methodology/Principal Findings The Ross–Macdonald model and a biodiversity-oriented model were parameterized using newly collected data and data from the literature. The basic reproduction number () estimated employing Ross–Macdonald model indicated that malaria cases occur in the study location. However, no malaria cases have been reported since 1980. In contrast, the biodiversity-oriented model corroborated the absence of malaria transmission. In addition, the diffuse competition mechanism was negatively correlated with the risk of malaria transmission, which suggests a protective effect provided by the forest ecosystem. There is a non-linear, unimodal correlation between the mechanism of dead-end transmission of parasites and the risk of malaria transmission, suggesting a protective effect only under certain circumstances (e.g., a high abundance of wild warm-blooded animals). Conclusions/Significance To achieve biological conservation and to eliminate Plasmodium parasites in human populations
Sickman, J.O.; Leydecker, A.L.; Chang, Cecily C.Y.; Kendall, C.; Melack, J.M.; Lucero, D.M.; Schimel, J.
Mechanisms underlying catchment export of nitrogen (N) during seasonal transitions (i.e., winter to spring and summer to autumn) were investigated in high-elevation catchments of the Sierra Nevada using stable isotopes of nitrate and water, intensive monitoring of stream chemistry and detailed catchment N-budgets. We had four objectives: (1) determine the relative contribution of snowpack and soil nitrate to the spring nitrate pulse, (2) look for evidence of biotic control of N losses at the catchment scale, (3) examine dissolved organic nitrogen (DON) export patterns to gain a better understanding of the biological and hydrological controls on DON loss, and (4) examine the relationship between soil physico-chemical conditions and N export. At the Emerald Lake watershed, nitrogen budgets and isotopic analyses of the spring nitrate pulse indicate that 50 to 70% of the total nitrate exported during snowmelt (ca. April to July) is derived from catchment soils and talus; the remainder is snowpack nitrate. The spring nitrate pulse occurred several weeks after the start of snowmelt and was different from export patterns of less biologically labile compounds such as silica and DON suggesting that: (1) nitrate is produced and released from soils only after intense flushing has occurred and (2) a microbial N-sink is operating in catchment soils during the early stages of snowmelt. DON concentrations varied less than 20-30% during snowmelt, indicating that soil processes tightly controlled DON losses.
Hoffmann, Peter; Singer, Werner; Becker, Erich; Latteck, Ralph; Keuer, Dieter
The seasonal variation and interannual variability of the gravity wave activity in the mesosphere/lower thermosphere (MLT) region at high and mid-latitudes is investigated. Variations of the gravity wave activity are examined in relation to the filtering processes due to the changes of the background winds, tides and planetary waves. Our studies are basing on wind measurements from meteor and MF radars at Andenes (69° N, 16° E) and Juliusruh (55° N, 13° E). These measurements are supplemented by mesospheric temperatures derived from meteor decay times. Additionally, turbulent energy dissipation rates have been estimated from spectral width measurements using a 3 MHz Doppler radar near Andenes. Particular attention is directed to the influence of the solar activity on the gravity wave activity during the summer months when the mesospheric winds show the strongest correlation with the solar activity. Possible dependencies between the occurrence rates of polar mesospheric summer echoes (PMSE) and the gravity wave activity are discussed. Furthermore, the activity of gravity waves and their dissipation are investigated in winter in relation with wind changes during sudden stratospheric warming (SSW) events. The summer/ winter behavior of the gravity wave activity will be compared to simulations with the simple general circulation model KMCM (K¨hlungsborn Mechanistic u Circulation Model) that extends up to 100 km. In all cases, the percentage rates of the kinetic energy of defined period ranges in relation to the total variances of the horizontal wind fluctuations are estimated.
Schicker, Rebekah Stewart; Hiruy, Neway; Melak, Berhanu; Gelaye, Woyneshet; Bezabih, Belay; Stephenson, Rob; Patterson, Amy E.; Tadesse, Zerihun; Emerson, Paul M.; Richards, Frank O.; Noland, Gregory S.
Background Mobile populations present unique challenges to malaria control and elimination efforts. Each year, a large number of individuals travel to northwest Amhara Region, Ethiopia to seek seasonal employment on large-scale farms. Agricultural areas typically report the heaviest malaria burden within Amhara thereby placing migrants at high risk of infection. Yet little is known about these seasonal migrants and their malaria-related risk factors. Methods and Findings In July 2013, a venue-based survey of 605 migrant laborers 18 years or older was conducted in two districts of North Gondar zone, Amhara. The study population was predominantly male (97.7%) and young (mean age 22.8 years). Plasmodium prevalence by rapid diagnostic test (RDT) was 12.0%; One quarter (28.3%) of individuals were anemic (hemoglobin <13 g/dl). Nearly all participants (95.6%) originated from within Amhara Region, with half (51.6%) coming from within North Gondar zone. Around half (51.2%) slept in temporary shelters, while 20.5% regularly slept outside. Only 11.9% of participants had access to a long lasting insecticidal net (LLIN). Reported net use the previous night was 8.8% overall but 74.6% among those with LLIN access. Nearly one-third (30.1%) reported having fever within the past two weeks, of whom 31.3% sought care. Cost and distance were the main reported barriers to seeking care. LLIN access (odds ratio [OR] = 0.30, P = 0.04) and malaria knowledge (OR = 0.50, P = 0.02) were significantly associated with reduced Plasmodium infection among migrants, with a similar but non-significant trend observed for reported net use the previous night (OR = 0.16, P = 0.14). Conclusions High prevalence of malaria and anemia were observed among a young population that originated from relatively proximate areas. Low access to care and low IRS and LLIN coverage likely place migrant workers at significant risk of malaria in this area and their return home may facilitate parasite transport to other
Xu, Liukang; Baldocchi, Dennis D
Understanding seasonal changes in photosynthetic parameters and stomatal conductance is crucial for modeling long-term carbon uptake and energy fluxes of ecosystems. Gas exchange measurements of CO2 and light response curves on blue oak leaves (Quercus douglasii H. & A.) were conducted weekly throughout the growing season to study the seasonality of photosynthetic capacity (Vcmax) and Ball-Berry slope (m) under prolonged summer drought and high temperature. A leaf photosynthetic model was used to determine Vcmax. There was a pronounced seasonal pattern in Vcmax. The maximum value of Vcmax, 127 micromol m(-2) s(-1), was reached shortly after leaf expansion in early summer, when air temperature was moderate and soil water availability was high. Thereafter, Vcmax declined as the soil water profile became depleted and the trees experienced extreme air temperatures, exceeding 40 degrees C. The decline in Vcmax was gradual in midsummer, however, despite extremely low predawn leaf water potentials (Psipd, approximately -4.0 MPa). Overall, temporal changes in Vcmax were well correlated with changes in leaf nitrogen content. During spring leaf development, high rates of leaf dark respiration (Rd, 5-6 micromol m(-2) s(-1)) were observed. Once a leaf reached maturity, Rd remained low, around 0.5 micromol m(-2) s(-1). In contrast to the strong seasonality of Vcmax, m and marginal water cost per unit carbon gain (partial partial differential E/ partial partial differential A) were relatively constant over the season, even when leaf Psipd dropped to -6.8 MPa. The constancy of partial partial differential E/ partial partial differential A suggests that stomata behaved optimally under severe water-stress conditions. We discuss the implications of our findings in the context of modeling carbon and water vapor exchange between ecosystems and the atmosphere.
Pakdad, Kamran; Hanafi-Bojd, Ahmad Ali; Vatandoost, Hassan; Sedaghat, Mohammad Mehdi; Raeisi, Ahmad; Moghaddam, Abdolreza Salahi; Foroushani, Abbas Rahimi
Malaria is considered as a major public health problem in southern areas of Iran. The goal of this study was to predict best ecological niches of three main malaria vectors of Iran: Anopheles stephensi, Anopheles culicifacies s.l. and Anopheles fluviatilis s.l. A databank was created which included all published data about Anopheles species of Iran from 1961 to 2015. The suitable environmental niches for the three above mentioned Anopheles species were predicted using maximum entropy model (MaxEnt). AUC (area under Roc curve) values were 0.943, 0.974 and 0.956 for An. stephensi, An. culicifacies s.l. and An. fluviatilis s.l respectively, which are considered as high potential power of model in the prediction of species niches. The biggest bioclimatic contributor for An. stephensi and An. fluviatilis s.l. was bio 15 (precipitation seasonality), 25.5% and 36.1% respectively, followed by bio 1 (annual mean temperature), 20.8% for An. stephensi and bio 4 (temperature seasonality) with 49.4% contribution for An. culicifacies s.l. This is the first step in the mapping of the country's malaria vectors. Hence, future weather situation can change the dispersal maps of Anopheles. Iran is under elimination phase of malaria, so that such spatio-temporal studies are essential and could provide guideline for decision makers for IVM strategies in problematic areas.
Chanda, Emmanuel; Kamuliwo, Mulakwa; Steketee, Richard W; Macdonald, Michael B; Babaniyi, Olusegun; Mukonka, Victor M
The Zambian national malaria control programme has made great progress in the fight against Malaria. The country has solid, consistent, and coordinated policies, strategies, and guidelines for malaria control, with government prioritizing malaria in both the National Health Strategic Plan and the National Development Plan. This has translated into high coverage of proven and effective key preventive, curative, and supportive interventions with concomitant marked reduction in both malaria cases and deaths. The achievements attained can be attributed to increased advocacy, communication and behaviour changes, efficient partnership coordination including strong community engagement, increased financial resources, and evidence-based deployment of key technical interventions in accordance with the national malaria control programme policy and strategic direction. The three-ones strategy has been key for increased and successful public-private sector partner coordination, strengthening, and mobilization. However, maintaining the momentum and the gains is critical as the programme strives to achieve universal coverage of evidence-based and proven interventions. The malaria control programme's focus is to maintain the accomplishments, by mobilizing more resources and partners, increasing the government funding towards malaria control, scaling up and directing interventions based on epidemiological evidence, and strengthen active malaria surveillance and response to reduce transmission and to begin considering elimination.
Ahmad Saleh, Ahmad Megahed; Adam, Samia Mohammad; Ibrahim, Abeer Mohammad Abdallah; Morsy, Tosson A
The majority of world's population-live in areas at risk of malaria transmission. Malaria is a serious Anopheles-borne disease that pauses symptoms like the flu, as a high fever, chills, and muscle pain also, anemia, bloody stools, coma, convulsion, fever, headache, jaundice, nausea, sweating and vomiting. Symptoms tend to come and go in cycles. Apart from Anopheles vector, malaria could be transmitted nosocomial, blood transfusion or needle-stick injury Some types of malaria may cause more serious damage problems to heart, lungs, kidneys, or brain. These types can be deadly. The primary factors contributing to the resurgence of malaria are the appearance of drug-resistant strains of the parasite, the spread of insecticide-resistant strains of the mosquito and the lack of licensed malaria vaccines of proven efficacy. In rare cases, people can get malaria if they come into contact with infected blood as in blood transfusion or needle-stick injury also nosocomial and congenital malaria was reported. This is a mini-review of malaria with information on the lethal to humans, Plasmodium falciparum, together with other recent developments in the field.
Rastad, Cecilia; Ulfberg, Jan; Sjoden, Per-Olow
Objective: There are few studies regarding the prevalence of seasonal variation in mood among children and adolescents. The main objective of this study was to estimate the prevalence of self-reported depressive mood during the winter season among Swedish adolescents and to investigate gender differences. Another aim was to analyze the factor…
Background This study aimed to investigate baseline data on malaria before the evaluation of new vector control strategies in an area of pyrethroid-resistance of vectors. The burden of malaria was estimated in terms of infection (prevalence and parasite density) and of clinical episodes. Methods Between December 2007 and December 2008 in the health district of Ouidah - Kpomassè - Tori Bossito (southern Benin), a descriptive epidemiological survey of malaria was conducted. From 28 selected villages, seven were randomized from which a total of 440 children aged 0 to 5 years were randomly selected. Clinical and parasitological information was obtained by active case detection of malaria episodes carried out during eight periods of six consecutive days scheduled at six weekly intervals and by cross-sectional surveys of asymptomatic infection. Entomological information was also collected. The ownership, the use and the correct use of long-lasting insecticide-treated nets (LLINs) were checked over weekly-survey by unannounced visits at home in the late evening. Results Mean parasite density in asymptomatic children was 586 P. falciparum asexual forms per μL of blood (95%CI 504-680). Pyrogenic parasite cut-off was estimated 2,000 P. falciparum asexual blood forms per μL. The clinical incidence of malaria was 1.5 episodes per child per year (95%CI 1.2-1.9). Parasitological and clinical variables did not vary with season. Anopheles gambiae s.l. was the principal vector closely followed by Anopheles funestus. Entomological inoculation rate was 5.3 (95%CI 1.1-25.9) infective bites per human per year. Frequency of the L1014F kdr (West) allele was around 50%. Annual prevalence rate of Plasmodium falciparum asymptomatic infection was 21.8% (95%CI 19.1-24.4) and increased according to age. Mean rates of ownership and use of LLINs were 92% and 70% respectively. The only correct use of LLINs (63%) conferred 26% individual protection against only infection (OR = 0.74 (95%IC 0
Highland Russet is a late-season potato variety with light russet skin notable for its high yield of uniform U.S. No. 1 tubers, and good processing and culinary qualities. It resulted from a 1990 cross between Ranger Russet and Russet Legend and has been evaluated for over 15 years in public and ind...
Smith, A W; Hendrickse, R G; Harrison, C; Hayes, R J; Greenwood, B M
In order to determine whether giving iron to iron-deficient children increases their susceptibility to malaria, 213 Gambian children aged between 6 months and 5 years with iron-deficiency anaemia were randomized to receive either oral iron or placebo during the rainy season when malaria transmission is maximal. Haematological and iron measurements improved significantly in the group given iron. Regular morbidity surveys showed that fever associated with parasitaemia occurred more frequently in the iron-treated group than in the placebo group. This difference was not significant for all parasitaemias grouped together, but became significant and progressively larger for parasitaemias of ten or more positive fields per 100 high power fields (P less than 0.025), and for parasitaemias of 50 or more positive fields per 100 high power fields (P less than 0.01). Three children in the iron-treated group but none in the placebo group had more than one episode of fever and parasitaemia. Splenomegaly rates rose appreciably during the study in both groups, but in children at age 2 years the splenomegaly rate at the end of the study was significantly greater in the iron-treated group. We concluded that there is a significantly increased risk of fever associated with severe malarial parasitaemia for children with iron-deficiency anaemia given iron during the season of maximal malaria transmission in this part of The Gambia.
Torrús, Diego; Carranza, Cristina; Manuel Ramos, José; Carlos Rodríguez, Juan; Rubio, José Miguel; Subirats, Mercedes; Ta-Tang, Thuy-Huong
Current diagnosis of malaria is based on the combined and sequential use of rapid antigen detection tests (RDT) of Plasmodium and subsequent visualization of the parasite stained with Giemsa solution in a thin and thick blood smears. If an expert microscopist is not available, should always be a sensitive RDT to rule out infection by Plasmodium falciparum, output the result immediately and prepare thick smears (air dried) and thin extensions (fixed with methanol) for subsequent staining and review by an expert microscopist. The RDT should be used as an initial screening test, but should not replace microscopy techniques, which should be done in parallel. The diagnosis of malaria should be performed immediately after clinical suspicion. The delay in laboratory diagnosis (greater than 3 hours) should not prevent the initiation of empirical antimalarial treatment if the probability of malaria is high. If the first microscopic examination and RDT are negative, they must be repeated daily in patients with high suspicion. If suspicion remains after three negative results must be sought the opinion of an tropical diseases expert. Genomic amplification methods (PCR) are useful as confirmation of microscopic diagnosis, to characterize mixed infections undetectable by other methods, and to diagnose asymptomatic infections with submicroscopic parasitaemia.
Videvall, Elin; Cornwallis, Charlie K; Palinauskas, Vaidas; Valkiūnas, Gediminas; Hellgren, Olof
Malaria parasites are highly virulent pathogens which infect a wide range of vertebrates. Despite their importance, the way different hosts control and suppress malaria infections remains poorly understood. With recent developments in next-generation sequencing techniques, however, it is now possible to quantify the response of the entire transcriptome to infections. We experimentally infected Eurasian siskins (Carduelis spinus) with avian malaria parasites (Plasmodium ashfordi), and used high-throughput RNA-sequencing to measure the avian transcriptome in blood collected before infection (day 0), during peak parasitemia (day 21 postinfection), and when parasitemia was decreasing (day 31). We found considerable differences in the transcriptomes of infected and uninfected individuals, with a large number of genes differentially expressed during both peak and decreasing parasitemia stages. These genes were overrepresented among functions involved in the immune system, stress response, cell death regulation, metabolism, and telomerase activity. Comparative analyses of the differentially expressed genes in our study to those found in other hosts of malaria (human and mouse) revealed a set of genes that are potentially involved in highly conserved evolutionary responses to malaria infection. By using RNA-sequencing we gained a more complete view of the host response, and were able to pinpoint not only well-documented host genes but also unannotated genes with clear significance during infection, such as microRNAs. This study shows how the avian blood transcriptome shifts in response to malaria infection, and we believe that it will facilitate further research into the diversity of molecular mechanisms that hosts utilize to fight malaria infections.
Hammadi, D; Boubidi, S C; Chaib, S E; Saber, A; Khechache, Y; Gasmi, M; Harrat, Z
Thanks to the malaria eradication campaign launched in Algeria in 1968, the number of malaria cases fell down significantly from 95,424 cases in 1960 to 30 cases in 1978. At that time the northern part of the country was declared free of Plasmodium falciparum. Only few cases belonging to P. vivax persisted in residual foci in the middle part of the country. In the beginning of the eighties, the south of the country was marked by an increase of imported malaria cases. The resurgence of the disease in the oases coincided with the opening of the Trans-Saharan road and the booming trade with the neighbouring southern countries. Several authors insisted on the risk of introduction of malaria or its exotic potential vectors in Algeria via this new road. Now, the totality of malaria autochthonous cases in Algeria are located in the south of the country where 300 cases were declared during the period (1980-2007). The recent outbreak recorded in 2007 at the borders with Mall and the introduction of Anopheles gambiae into the Algerian territory show the vulnerability of this area to malaria which is probably emphasized by the local environmental changes. The authors assess the evolution of malaria in the Sahara region and draw up the distribution of the anopheles in this area.
Background In 2009 a total of 153,408 malaria deaths were reported in Africa. Eleven countries showed a reduction of more than 50% in either confirmed malaria cases or malaria admissions and deaths in recent years. However, many African countries are not on track to achieve the malaria component of the Millennium Development Goal (MDG) 6. The African Leaders Malaria Alliance (ALMA) working session at the 15th African Union Summit discussed the bottlenecks to achieving MDG 6 (specifically halting and beginning to reverse the incidence of malaria by 2015), success factors, and what countries needed to do to accelerate achievement of the MDG. The purpose of this article is to reflect on the proceedings of the ALMA working session. Methods Working methods of the session included speeches and statements by invited speakers and high-level panel discussions. Discussion The main bottlenecks identified related to the capacity of the health systems to deliver quality care and accessibility issues; need for strong, decentralized malaria-control programmes with linkages with other health and development sectors, the civil society and private sector entities; benefits of co-implementation of malaria control programmes with child survival or other public health interventions; systematic application of integrated promotive, preventive, diagnostic and case management interventions with full community participation; adapting approaches to local political, socio-cultural and administrative environments. The following prerequisites for success were identified: a clear vision and effective leadership of national malaria control programmes; high level political commitment to ensure adequate capacity in expertise, skill mix and number of managers, technicians and service providers; national ownership, intersectoral collaboration and accountability, as well as strong civil society and private sector involvement; functional epidemiological surveillance systems; and levering of African
Simon, Marianne; López-García, Purificación; Deschamps, Philippe; Moreira, David; Restoux, Gwendal; Bertolino, Paola; Jardillier, Ludwig
Small eukaryotes have key roles in aquatic ecosystems, influencing their local environment, global biogeochemical cycles and climate. Their impact depends on community structure, which varies along time. However, very few studies take into account temporal variation. This is especially true for small, shallow freshwater systems, which remain largely understudied despite their wide variety, global surface and intense microbial activity. We have monthly followed changes in the community structure of small microbial eukaryotes (0.2–5 μm cell diameter) for 2 years in four ponds and one brook located in North-Western France based on massive 18S rDNA amplicon 454 pyrosequencing. We detected a total of 3742 stringently defined operational taxonomic units (OTUs) encompassing all recognized eukaryotic supergroups and lineages of uncertain affiliation. Although geographically close, protist communities in the five ecosystems were contrasting, with very few shared OTUs, suggesting that environmental selection mainly drives community structure. The temporal dynamics of different high-rank taxa appeared complex and rapid at monthly scales. Despite this, a clear and reproducible seasonality was observed. As expected, low-abundance OTUs dominated the community. Although some of them appeared sporadically or remained at low frequencies during the survey, others occasionally reached relatively high abundances, sometimes recurrently. This shows that at least a fraction of low-abundance eukaryotes constitutes a seed bank. The annual proportion of primary producers, free-living heterotrophs and parasites appeared remarkably constant among the different ecosystems, suggesting underlying trends of ecosystem carrying capacity for these functional groups. PMID:25853803
Ruggiero, P.; Kaminsky, G.M.; Gelfenbaum, G.; Voigt, B.
A beach morphology monitoring program was initiated during summer 1997 along the Columbia River littoral cell (CRLC) on the coasts of northwest Oregon and southwest Washington, USA. This field program documents the seasonal through interannual morphological variability of these high-energy dissipative beaches over a variety of spatial scales. Following the installation of a dense network of geodetic control monuments, a nested sampling scheme consisting of cross-shore topographic beach profiles, three-dimensional topographic beach surface maps, nearshore bathymetric surveys, and sediment size distribution analyses was initiated. Beach monitoring is being conducted with state-of-the-art real-time kinematic differential global positioning system survey methods that combine both high accuracy and speed of measurement. Sampling methods resolve variability in beach morphology at alongshore length scales of approximately 10 meters to approximately 100 kilometers and cross-shore length scales of approximately 1 meter to approximately 2 kilometers. During the winter of 1997/1998, coastal change in the US Pacific Northwest was greatly influenced by one of the strongest El Nin??o events on record. Steeper than typical southerly wave angles resulted in alongshore sediment transport gradients and shoreline reorientation on a regional scale. The La Nin??a of 1998/1999, dominated by cross-shore processes associated with the largest recorded wave year in the region, resulted in net beach erosion along much of the littoral cell. The monitoring program successfully documented the morphological response to these interannual forcing anomalies as well as the subsequent beach recovery associated with three consecutive moderate wave years. These morphological observations within the CRLC can be generalized to explain overall system patterns; however, distinct differences in large-scale coastal behavior (e.g., foredune ridge morphology, sandbar morphometrics, and nearshore beach slopes
Pasmanik, M.; Callard, G.V.
Testosterone (T) exerts its actions in brain directly via androgen receptors or, after aromatization to estradiol, via estrogen receptors. Brain aromatase activity in teleost fish is 100-1000 times greater than in mammals and would be expected to significantly reduce the quantity of androgen available for receptor binding. Experiments were carried out on the goldfish Carassius auratus to determine if androgen receptors are present in teleost brain and whether their physicochemical properties reflect elevated aromatase. Cytosolic and nuclear extracts were assayed with the use of (/sup 3/H)T and charcoal, Sephadex LH-20, or DNA-cellulose chromatography to separate bound and free steroids. Binding activity was saturable and had an equally high affinity for T and 5 alpha-dihydrotestosterone. Although mibolerone was a relatively weak competitor, the putative teleost androgen 11-ketotestosterone, methyltrienolone (R1881), estradiol, progesterone, and cortisol were poor ligands. Characteristics that distinguish this receptor from a steroid-binding protein in goldfish serum are the presence of binding activity in both nuclear and cytosolic extracts, a low rate of ligand-receptor dissociation, electrophoretic mobility, sedimentation properties in low vs. high salt, and tissue distribution. DNA cellulose-adhering and nonadhering forms were detected, but these did not differ in other variables measured. Although goldfish androgen receptors resembled those of mammals in all important physicochemical characteristics, they were unusually abundant compared to levels in rat brain, but comparable to levels in prostate and other male sex hormone target organs. Moreover, there were seasonal variations in total receptors, with a peak at spawning (April) 4- to 5-fold higher than values in reproductively inactive fish.
Ruiz, Daniel; Cerón, Viviana; Molina, Adriana M; Quiñónes, Martha L; Jiménez, Mónica M; Ahumada, Martha; Gutiérrez, Patricia; Osorio, Salua; Mantilla, Gilma; Connor, Stephen J; Thomson, Madeleine C
As part of the Integrated National Adaptation Pilot project and the Integrated Surveillance and Control System, the Colombian National Institute of Health is working on the design and implementation of a Malaria Early Warning System framework, supported by seasonal climate forecasting capabilities, weather and environmental monitoring, and malaria statistical and dynamic models. In this report, we provide an overview of the local ecoepidemiologic settings where four malaria process-based mathematical models are currently being implemented at a municipal level. The description includes general characteristics, malaria situation (predominant type of infection, malaria-positive cases data, malaria incidence, and seasonality), entomologic conditions (primary and secondary vectors, mosquito densities, and feeding frequencies), climatic conditions (climatology and long-term trends), key drivers of epidemic outbreaks, and non-climatic factors (populations at risk, control campaigns, and socioeconomic conditions). Selected pilot sites exhibit different ecoepidemiologic settings that must be taken into account in the development of the integrated surveillance and control system.
Ruiz, Daniel; Cerón, Viviana; Molina, Adriana M.; Quiñónes, Martha L.; Jiménez, Mónica M.; Ahumada, Martha; Gutiérrez, Patricia; Osorio, Salua; Mantilla, Gilma; Connor, Stephen J.; Thomson, Madeleine C.
As part of the Integrated National Adaptation Pilot project and the Integrated Surveillance and Control System, the Colombian National Institute of Health is working on the design and implementation of a Malaria Early Warning System framework, supported by seasonal climate forecasting capabilities, weather and environmental monitoring, and malaria statistical and dynamic models. In this report, we provide an overview of the local ecoepidemiologic settings where four malaria process-based mathematical models are currently being implemented at a municipal level. The description includes general characteristics, malaria situation (predominant type of infection, malaria-positive cases data, malaria incidence, and seasonality), entomologic conditions (primary and secondary vectors, mosquito densities, and feeding frequencies), climatic conditions (climatology and long-term trends), key drivers of epidemic outbreaks, and non-climatic factors (populations at risk, control campaigns, and socioeconomic conditions). Selected pilot sites exhibit different ecoepidemiologic settings that must be taken into account in the development of the integrated surveillance and control system. PMID:24891460
Strassberg, Gil; Scanlon, Bridget R.; Rodell, Matthew
This study presents the first direct comparison of variations in seasonal GWS derived from GRACE TWS and simulated SM with GW-level measurements in a semiarid region. Results showed that variations in GWS and SM are the main sources controlling TWS changes over the High Plains, with negligible storage changes from surface water, snow, and biomass. Seasonal variations in GRACE TWS compare favorably with combined GWS from GW-level measurements (total 2,700 wells, average 1,050 GW-level measurements per season) and simulated SM from the Noah land surface model (R = 0.82, RMSD = 33 mm). Estimated uncertainty in seasonal GRACE-derived TWS is 8 mm, and estimated uncertainty in TWS changes is 11 mm. Estimated uncertainty in SM changes is 11 mm and combined uncertainty for TWS-SM changes is 15 mm. Seasonal TWS changes are detectable in 7 out of 9 monitored periods and maximum changes within a year (e.g. between winter and summer) are detectable in all 5 monitored periods. Grace-derived GWS calculated from TWS-SM generally agrees with estimates based on GW-level measurements (R = 0.58, RMSD = 33 mm). Seasonal TWS-SM changes are detectable in 5 out of the 9 monitored periods and maximum changes are detectable in all 5 monitored periods. Good correspondence between GRACE data and GW-level measurements from the intensively monitored High Plains aquifer validates the potential for using GRACE TWS and simulated SM to monitor GWS changes and aquifer depletion in semiarid regions subjected to intensive irrigation pumpage. This method can be used to monitor regions where large-scale aquifer depletion is ongoing, and in situ measurements are limited, such as the North China Plain or western India. This potential should be enhanced by future advances in GRACE processing, which will improve the spatial and temporal resolution of TWS changes, and will further increase applicability of GRACE data for monitoring GWS.
Bende-Michl, Ulrike; Verburg, Kirsten; Cresswell, Hamish P
To explore the value of high-frequency monitoring to characterise and explain riverine nutrient concentration dynamics, total phosphorus (TP), reactive phosphorus (RP), ammonium (NH4-N) and nitrate (NO3-N) concentrations were measured hourly over a 2-year period in the Duck River, in north-western Tasmania, Australia, draining a 369-km(2) mixed land use catchment area. River discharge was observed at the same location and frequency, spanning a wide range of hydrological conditions. Nutrient concentrations changed rapidly and were higher than previously observed. Maximum nutrient concentrations were 2,577 μg L(-1) TP, 1,572 μg L(-1) RP, 972 μg L(-1) NH₄-N and 1,983 μg L(-1) NO₃-N, respectively. Different nutrient response patterns were evident at seasonal, individual event and diurnal time scales-patterns that had gone largely undetected in previous less frequent water quality sampling. Interpretation of these patterns in terms of nutrient source availability, mobilisation and delivery to the stream allowed the development of a conceptual model of catchment nutrient dynamics. Functional stages of nutrient release were identified for the Duck River catchment and were supported by a cluster analysis which confirmed the similarities and differences in nutrient responses caused by the sequence of hydrologic events: (1) a build-up of nutrients during periods with low hydrologic activity, (2) flushing of readily available nutrient sources at the onset of the high flow period, followed by (3) a switch from transport to supply limitation, (4) the accessibility of new nutrient sources with increasing catchment wetness and hydrologic connectivity and (5) high nutrient spikes occurring when new sources become available that are easily mobilised with quickly re-established hydrologic connectivity. Diurnal variations that could be influenced by riverine processes and/or localised point sources were also identified as part of stage (1) and during late recession of some of
Li, Zhongjie; Yang, Yichao; Xiao, Ning; Zhou, Sheng; Lin, Kangming; Wang, Duoquan; Zhang, Qian; Jiang, Weikang; Li, Mei; Feng, Xinyu; Yu, Jianxin; Ren, Xiang; Lai, Shengjie; Sun, Junling; Fang, Zhongliao; Hu, Wenbiao; Clements, Archie C.A.; Zhou, Xiaonong
During May-August 2013, a malaria outbreak comprising 874 persons in Shanglin County, China, was detected among 4,052 persons returning from overseas. Ghana was the predominant destination country, and 92.3% of malarial infections occurred in gold miners. Preventive measures should be enhanced for persons in high-risk occupations traveling to malaria-endemic countries. PMID:25897805
Merlin, Aurélie; Chauvin, Alain; Lehebel, Anne; Brisseau, Nadine; Froger, Sébastien; Bareille, Nathalie; Chartier, Christophe
A two-year study was carried out to assess the feasibility of a targeted selective treatment to control gastrointestinal nematodes (GIN) in 24 groups of first grazing season (FGS) cattle. A two-step procedure aiming at defining exposure risk at group level and at identifying the most infected individuals within groups through measurement of the average daily weight gain (ADWG) at housing was used. The first step was to define retrospectively, by grazing management practices (GMP) indicators, two levels of groups' exposure to GIN determined by anti O. ostertagi antibody ODR level (cut-off 0.7). For the low level of exposure, no relationship between parasitological parameters and heifer growth was seen, whereas for the high level ADWG was negatively correlated with increasing Ostertagia ODR values. The best classification was obtained with an expert system modelling the number of Ostertagia L3 generations on plots. GMP input for the expert system included standard data (turnout/housing data and supplementary feeding amount) combined with paddock rotation planning and monthly temperatures. The threshold of 3 successive generations of L3 or more on plots allowed identifying the groups according to low or high infection exposure level, except two groups that were misidentified as being highly exposed. In the second step, individual ADWG was found to be negatively associated with Ostertagia ODR in heifers from groups classified as highly exposed (≥3 generations of L3). In these groups, sensitivity and specificity of ADWG thresholds were calculated for several individual Ostertagia ODR thresholds. The best compromise between sensitivity (i.e., correctly treating the heifers that need to be treated) and specificity (i.e., not treating animals that should not be treated) was equivalent respectively to 76% and 56% (AUC≈0.7) and was reached using an end-season ADWG threshold of 683g/day to detect animals exhibiting an Ostertagia ODR cut-off at 0.93. Other ADWG thresholds
Background In moving toward malaria elimination, one strategy is to implement an active surveillance system for effective case management. Thailand has developed and implemented the electronic Malaria Information System (eMIS) capturing individualized electronic records of suspected or confirmed malaria cases. Objective The main purpose of this study was to determine how well the eMIS improves the quality of Thailand’s malaria surveillance system. In particular, the focus of the study was to evaluate the effectiveness of the eMIS in terms of the system users’ perception and the system outcomes (ie, quality of data) regarding the management of malaria patients. Methods A mixed-methods technique was used with the framework based on system effectiveness attributes: data quality, timeliness, simplicity, acceptability, flexibility, stability, and usefulness. Three methods were utilized: data records review, survey of system users, and in-depth interviews with key stakeholders. From the two highest endemic provinces, paper forms matching electronic records of 4455 noninfected and 784 malaria-infected cases were reviewed. Web-based anonymous questionnaires were distributed to all 129 eMIS data entry staff throughout Thailand, and semistructured interviews were conducted with 12 management-level officers. Results The eMIS is well accepted by system users at both management and operational levels. The data quality has enabled malaria personnel to perform more effective prevention and control activities. There is evidence of practices resulting in inconsistencies and logical errors in data reporting. Critical data elements were mostly completed, except for a few related to certain dates and area classifications. Timeliness in reporting a case to the system was acceptable with a delay of 3-4 days. The evaluation of quantitative and qualitative data confirmed that the eMIS has high levels of simplicity, acceptability, stability, and flexibility. Conclusions Overall, the
de Alencar, Aristóteles Comte; de Lacerda, Marcus Vinícius Guimarães; Okoshi, Katashi; Okoshi, Marina Politi
Involvement of the cardiovascular system in patients with infectious and parasitic diseases can result from both intrinsic mechanisms of the disease and drug intervention. Malaria is an example, considering that the endothelial injury by Plasmodium-infected erythrocytes can cause circulatory disorders. This is a literature review aimed at discussing the relationship between malaria and endothelial impairment, especially its effects on the cardiovascular system. We discuss the implications of endothelial aggression and the interdisciplinarity that should guide the malaria patient care, whose acute infection can contribute to precipitate or aggravate a preexisting heart disease. PMID:25014058
Sundararajan, Radhika; Kalkonde, Yogeshwar; Gokhale, Charuta; Greenough, P. Gregg; Bang, Abhay
Background Malaria infection accounts for over one million deaths worldwide annually. India has the highest number of malaria deaths outside Africa, with half among Indian tribal communities. Our study sought to identify barriers to malaria control within tribal populations in malaria-endemic Gadchiroli district, Maharashtra. Methods and Findings This qualitative study was conducted via focus groups and interviews with 84 participants, and included tribal villagers, traditional healers, community health workers (CHWs), medical officers, and district officials. Questions assessed knowledge about malaria, behavior during early stages of infection, and experiences with prevention among tribal villagers and traditional healers. CHWs, medical officers, and district officials were asked about barriers to treating and preventing malaria among tribal populations. Data were inductively analyzed and assembled into broader explanation linking barriers to geographical, cultural and social factors. Findings indicate lack of knowledge regarding malaria symptoms and transmission. Fever cases initially present to traditional healers or informal providers who have little knowledge of malaria or high-risk groups such as children and pregnant women. Tribal adherence with antimalarial medications is poor. Malaria prevention is inadequate, with low-density and inconsistent use of insecticide-treated nets (ITNs). Malaria educational materials are culturally inappropriate, relying on dominant language literacy. Remote villages and lack of transport complicate surveillance by CHWs. Costs of treating malaria outside the village are high. Conclusions Geographic, cultural, and social factors create barriers to malaria control among tribal communities in India. Efforts to decrease malaria burden among these populations must consider such realities. Our results suggest improving community-level knowledge about malaria using culturally-appropriate health education materials; making traditional
Background Orissa state in eastern India accounts for the highest malaria burden to the nation. However, evidences are limited on its treatment-seeking behaviour in the state. We assessed the treatment-seeking behaviour towards febrile illness in a malaria endemic district in Orissa. Methods A cross-sectional community-based survey was carried out during the high malaria transmission season of 2006 in Boudh district. Respondents (n = 300) who had fever with chills within two weeks prior to the day of data collection were selected through a multi-stage sampling and interviewed with a pre-tested and structured interview schedule. Malaria treatment providers (n = 23) were interviewed in the district to gather their insights on factors associated with prompt and effective treatment through a semi-structured and open-ended interview guideline. Results Majority of respondents (n = 281) sought some sort of treatment e.g. government health facility (35.7%), less qualified providers (31.3%), and community level health workers and volunteers (24.3%). The single most common reason (66.9%) for choosing a provider was proximity. Over a half (55.7%) sought treatment from appropriate providers within 48 hours of onset of symptoms. Respondents under five years (OR 2.00, 95% CI 0.84-4.80, P = 0.012), belonging to scheduled tribe community (OR 2.13, 95% CI 1.11-4.07, P = 0.022) and visiting a provider more than five kilometers (OR 2.04, 95% CI 1.09-3.83, P = 0.026) were more likely to have delayed or inappropriate treatment. Interviews with the providers indicated that patients' lack of trust in community volunteers providing treatment led to inappropriate treatment-seeking from the less qualified providers. The reasons for the lack of trust included drug side effects, suspicions about drug quality, stock-outs of drugs and inappropriate attitude of the provider. Conclusion Large-scale involvement of less qualified providers is suggested in the malaria control programme as volunteers
Although it is not certain when malaria began to appear in Korea, malaria is believed to have been an endemic disease from ancient times. It was Dr. H. N. Allen (1858-1932) who made the first description and diagnosis of malaria in terms of Western medicine. In his first year report (1885) of Korean Government Hospital he mentioned malaria as the most prevalent disease. Very effective anti-malarial drug quinine was imported and it made great contribution in treating malaria. After Japan had annexed Korea in 1910, policies for public health system were fundamentally revised. Japan assumed control of Korean medical institutions and built high-quality Western hospitals for the health care of Japanese residents. The infectious diseases which were under special surveillance were cholera, typhoid fever, dysentery, typhus, scarlet fever, smallpox, and paratyphoid fever. Among chronic infectious diseases tuberculosis and leprosy were those under special control. Malaria, however, was not one of these specially controlled infectious diseases although it was widely spread throughout the peninsula. But serious studies on malaria were carried out by Japanese medical scientists. In particular, a Japanese parasitologist Kobayasi Harujiro(1884-1969) carried out extensive studies on human parasites, including malaria, in Korea. According to his study, most of the malaria in Korea turned out to be tertian fever. In spite of its high prevalence, malaria did not draw much attention from the colonial authorities and no serious measure was taken since tertian fever is a mild form of malaria caused by Plasmodium vivax and is not so much fatal as tropical malaria caused by P. falciparum. And tertian malaria was easily controlled by taking quinine. Although the majority of malaria in Korea was tertian fever, other types were not absent. Quartan fever was not rarely reported in 1930s. The attitude of colonial authorities toward malaria in Korea was contrasted with that in Taiwan. After
Cherif, Mariama K; Sanou, Guillaume S; Bougouma, Edith C; Diarra, Amidou; Ouédraogo, Alphonse; Dolo, Amagana; Troye-Blomberg, Marita; Cavanagh, David R; Theisen, Michael; Modiano, David; Sirima, Sodiomon B; Nebié, Issa
In the present study, the influences of FcγRIIA polymorphism on susceptibility to malaria and antibody responses to Plasmodium falciparum antigens were analyzed in children. We recruited 96 healthy children between 3 and 10 years at the beginning of the high transmission season and we followed up for 5 months through the high transmission season to assess the parasitological, immunological and genetic endpoints in relation to clinical malaria status. There was a similar distribution of homozygous and heterozygous individuals carrying the FcγRIIA-131R/R and FcγRIIA-131R/H allele, whereas the number of FcγRIIA-131H/H homozygous individuals was lower. P. falciparum infection frequency was not associated with the FcγRIIa-131R/H polymorphism. Only IgG antibody responses to GLURP R0 showed a significant association between antibody levels and FcγRIIA polymorphism (p=0.02). IgG levels to MSP2a were significantly higher in children who did not experience any clinical malaria episode compared to those who experienced at least one malaria episode (p=0.019). Cytophilic and non-cytophylic IgG subclass levels were higher in children without malaria than those who experienced at least one malaria episode. This difference was statistically significant for IgG1 to MSP3 (p=0.003) and to MSP2a (p=0.006); IgG3 to MSP2a (p=0.007) and to GLURP R0 (p=0.044); IgG2 to MSP2b (p=0.007) and IgG4 to MSP3 (p=0.051) and to MSP2a (p=0.049). In this study, homozygous carriers of the FcγRIIA-131R/R allele had higher malaria-specific antibody levels compare to the heterozygous carriers FcγRIIA-131R/H alleles and to homozygous carriers of FcγRIIA-131H/H alleles. The pre-existing antibodies responses were related to a reduced subsequent risk of clinical malaria.
Gesquiere, Laurence R.; Onyango, Patrick O.; Alberts, Susan C.; Altmann, Jeanne
In conditions characterized by energetic constraints, such as in periods of low food availability, some trade-offs between reproduction and self-maintenance may be necessary; even year-round breeders may then be forced to exhibit some reproductive seasonality. Prior research has largely focused on female reproduction and physiology, and few studies have evaluated the impact of environmental factors on males. Here we assessed the effects of season and ambient temperatures on fecal glucocorticoid (fGC) and testosterone (fT) levels in male baboons in Amboseli, Kenya. The Amboseli basin is a highly challenging, semi-arid tropical habitat that is characterized by strongly seasonal patterns of rainfall and by high ambient temperatures. We previously reported that female baboons were impacted by these challenging environmental conditions. We ask here whether male baboons in the same environment and groups as females exhibit similar physiological effects. We found that after accounting for male age and individual variability, males exhibited higher fGC levels and lower fT levels during the dry season than during the wet season. Furthermore, fT but not fGC levels were lower in months of high average daily maximum temperatures, suggesting a direct impact of heat on testes. Our results demonstrate that male baboons, like females, experience ecological stress that alters their reproductive physiology. The impact of the environment on male reproduction deserves more attention both in its own right and because alteration in male physiology may contribute to the reduction in female fertility observed in challenging environments. PMID:20721938
Yang, Bo; Chen, Hechang; Gu, Xiao; Bai, Yuan
Malaria, a life-threatening infectious disease, spreads rapidly via parasites. Malaria prevention is more effective and efficient than treatment. However, the existing surveillance systems used to prevent malaria are inadequate, especially in areas with limited or no access to medical resources. In this paper, in order to monitor the spreading of malaria, we develop an intelligent surveillance system based on our existing algorithms. First, a visualization function and active surveillance were implemented in order to predict and categorize areas at high risk of infection. Next, socioeconomic and climatological characteristics were applied to the proposed prediction model. Then, the redundancy of the socioeconomic attribute values was reduced using the stepwise regression method to improve the accuracy of the proposed prediction model. The experimental results indicated that the proposed IASM predicted malaria outbreaks more close to the real data and with fewer variables than other models. Furthermore, the proposed model effectively identified areas at high risk of infection. PMID:27563343
Analytical clinical summaries are presented on the following: Summary and analysis of therapeutic effect of new drugs in human volunteers with...Falciparum Malaria; Summary and analysis of therapeutic effect of new drugs in human volunteers with Vivax Malaria; Potentiation by drug combination...Problems of resistance for both old and new drugs ; Analysis of P. berghei infections; Studies on mechanisms of drug action; Cumulative summary of all new drug trials.
Alvarez, Jesus R; Al-Khan, Abdulla; Apuzzio, Joseph J
Recently, there has been a resurgence of malaria in densely populated areas of the United States secondary to human migration from endemic areas where factors such as cessation of vector control, vector resistance to insecticides, disease resistance to drugs, environmental changes, political instability, and indifference, have played a role for malaria becoming an overwhelming infection of these tropical underdeveloped countries. It is important for health care providers of gravida to be alert of the disease and its effects on pregnancy.
Sturrock, Hugh J. W.; Roberts, Kathryn W.; Wegbreit, Jennifer; Ohrt, Colin; Gosling, Roly D.
As countries move toward malaria elimination, imported infections become increasingly significant as they often represent the majority of cases, can sustain transmission, cause resurgences, and lead to mortality. Here we review and critique current methods to prevent malaria importation in countries pursuing elimination and explore methods applied in other transmission settings and to other diseases that could be transferred to support malaria elimination. To improve intervention targeting we need a better understanding of the characteristics of populations importing infections and their patterns of migration, improved methods to reliably classify infections as imported or acquired locally, and ensure early and accurate diagnosis. The potential for onward transmission in the most receptive and vulnerable locations can be predicted through high-resolution risk mapping that can help malaria elimination or prevention of reintroduction programs target resources. Cross border and regional initiatives can be highly effective when based on an understanding of human and parasite movement. Ultimately, determining the optimal combinations of approaches to address malaria importation will require an evaluation of their impact, cost effectiveness, and operational feasibility. PMID:26013369
Faude, Oliver; Schnittker, Reinhard; Schulte-Zurhausen, Roman; Müller, Florian; Meyer, Tim
We aimed at comparing the endurance effects of high-intensity interval training (HIIT) with high-volume running training (HVT) during pre-season conditioning in 20 high-level youth football players (15.9 (s 0.8) years). Players either conducted HVT or HIIT during the summer preparation period. During winter preparation they performed the other training programme. Before and after each training period several fitness tests were conducted: multi-stage running test (to assess the individual anaerobic threshold (IAT) and maximal running velocity (Vmax)), vertical jumping height, and straight sprinting. A significant increase from pre- to post-test was observed in IAT velocity (P < 0.001) with a greater increase after HVT (+0.8 km · h(-1) vs. +0.5 km · h(-1) after HIIT, P = 0.04). Maximal velocity during the incremental exercise test also slightly increased with time (P = 0.09). Forty per cent (HIIT) and 15% (HVT) of all players did not improve IAT beyond baseline variability. The players who did not respond to HIIT were significantly slower during 30 m sprinting than responders (P = 0.02). No further significant differences between responders and non-responders were observed. Jump heights deteriorated significantly after both training periods (P < 0.003). Both training programmes seem to be promising means to improve endurance capacity in high-level youth football players during pre-season conditioning.
Konradsen, F.; Steele, P.; Perera, D.; van der Hoek, W.; Amerasinghe, P. H.; Amerasinghe, F. P.
The study provides estimates of the cost of various malaria control measures in an area of North-Central Province of Sri Lanka where the disease is endemic. We assumed that each measure was equally effective. In these terms, impregnating privately purchased bednets with insecticide was estimated to cost Rs 48 (US(40.87) per individual protected per year, less than half the cost of spraying houses with residual insecticides. Larviciding of vector breeding sites and especially the elimination of breeding habitats by flushing streams through seasonal release of water from upstream reservoirs was estimated to be cheaper than other preventive measures (Rs 27 (US$ 0.49) and Rs 13 (US$ 0.24) per individual protected, respectively). Inclusion of both operational and capital costs of treatment indicates that the most cost-effective intervention for the government was a centrally located hospital with a relatively large catchment area (Rs 71 (US$ 1.29) per malaria case treated). Mobile clinics (Rs 153 (US$ 2.78) per malaria case treated) and a village treatment centre (Rs 112 (US$ 2.04)) per malaria case treated) were more expensive options for the government, but were considerably cheaper for households than the traditional hospital facilities. This information can guide health planners and government decision-makers in choosing the most appropriate combination of curative and preventive measures to control malaria. However, the option that is cheapest for the government may not be so for the householders, and further studies are needed to estimate the effectiveness of the various preventive measures. PMID:10327708
Parham, Paul E; Michael, Edwin
The impact of climate change on human health has received increasing attention in recent years, with potential impacts due to vector-borne diseases only now beginning to be understood. As the most severe vector-borne disease, with one million deaths globally in 2006, malaria is thought most likely to be affected by changes in climate variables due to the sensitivity of its transmission dynamics to environmental conditions. While considerable research has been carried out using statistical models to better assess the relationship between changes in environmental variables and malaria incidence, less progress has been made on developing process-based climate-driven mathematical models with greater explanatory power. Here, we develop a simple model of malaria transmission linked to climate which permits useful insights into the sensitivity of disease transmission to changes in rainfall and temperature variables. Both the impact of changes in the mean values of these key external variables and importantly temporal variation in these values are explored. We show that the development and analysis of such dynamic climate-driven transmission models will be crucial to understanding the rate at which P. falciparum and P. vivax may either infect, expand into or go extinct in populations as local environmental conditions change. Malaria becomes endemic in a population when the basic reproduction number R0 is greater than unity and we identify an optimum climate-driven transmission window for the disease, thus providing a useful indicator for determing how transmission risk may change as climate changes. Overall, our results indicate that considerable work is required to better understand ways in which global malaria incidence and distribution may alter with climate change. In particular, we show that the roles of seasonality, stochasticity and variability in environmental variables, as well as ultimately anthropogenic effects, require further study. The work presented here
Mbenda, Huguette Gaelle Ngassa; Awasthi, Gauri; Singh, Poonam K; Gouado, Inocent; Das, Aparup
Cameroon, a west-central African country with a ~ 20 million population, is commonly regarded as 'Africa in miniature' due to the extensive biological and cultural diversities of whole Africa being present in a single-country setting. This country is inhabited by ancestral human lineages in unique eco-climatic conditions and diverse topography. Over 90 percent Cameroonians are at risk of malaria infection, and ~ 41 percent have at least one episode of malaria each year. Historically, the rate of malaria infection in Cameroon has fluctuated over the years; the number of cases was about 2 million in 2010 and 2011. The Cameroonian malaria control programme faces an uphill task due to high prevalence of multidrug-resistant parasites and insecticide-resistant malaria vectors. Above all, continued human migration from the rural to urban areas as well as population exchange with adjoining countries, high rate of ecological instabilities caused by deforestation, poor housing, lack of proper sanitation and drainage system might have resulted in the recent increase in incidences of malaria and other vector-borne diseases in Cameroon. The available data on eco-environmental variability and intricate malaria epidemiology in Cameroon reflect the situation in the whole of Africa, and warrant the need for in-depth study by using modern surveillance tools for meaningful basic understanding of the malaria triangle (host-parasite-vector-environment).
Tuomi, Laura; Lehtiranta, Jonni
When forecasting surface waves in seasonally ice-covered seas, the inclusion of ice conditions in the modelling is important. The ice cover affects the propagation and also changes the fetch over which the waves grow. In wave models the ice conditions are often still given as a boundary condition and handled by excluding areas where the ice concentration exceeds a certain threshold value. The ice data used are typically based on satellite analysis or expert analysis of local Ice Services who combine data from different sources. This type of data is sufficiently accurate to evaluate the near-real time ice concentrations, but when making forecasts it is also important to account for the possible changes in ice conditions. For example in a case of a high wind situation, there can be rapid changes in the ice field, when the wind and waves may push the ice towards shores and cause fragmentation of ice field. To enhance handling of ice conditions in the Baltic Sea wave forecasts, utilisation of ice model data was studied. Ice concentration, thickness produced by FMI's operational ice model HELMI were used to provide ice data to wave model as follows: Wave model grid points where the ice concentration was more than or equal to 70% and the ice thickness more than1 cm, were excluded from calculations. Ice concentrations smaller than that were taken into account as additional grid obstructions by decreasing the wave energy passed from one grid cell to another. A challenge in evaluating wave forecast accuracy in partly ice covered areas it that there's typically no wave buoy data available, since the buoys have to be recovered well before the sea area freezes. To evaluate the accuracy of wave forecast in partially ice covered areas, significant wave heights from altimeter's ERS2, Envisat, Jason-1 and Jason-2 were extracted from Ifremer database. Results showed that the more frequent update of the ice data was found to improve the wave forecast especially during high wind
... ecological needs of the different species. In compliance with section 603(b)(2) of the RFA, the objectives of... Act, and the Coastal Zone Management Act. In compliance with section 603(c) of the Regulatory... considering the ecological needs of the different species. The opening of the fishing season could vary...
... blue sharks) in the northwestern Atlantic Ocean, including the Gulf of Mexico and the Caribbean Sea... gear types, and reduced crew turnover. A shorter season may reduce the at- sea time associated with... sharks in the summer presents a safety-at-sea issue as it is dangerous in the Florida summer heat to...
Zoppi de Roa, Evelyn; Gordon, Elizabeth; Montiel, Edie; Delgado, Laura; Berti, Jesús; Ramos, Santiago
The southern region of the Paria Peninsula shows a high malaria incidence. This work relates the abundances of cyclopoid species and the malaria vector Anopheles aquasalis to certain abiotic parameters and vegetation features. Samples were collected over a 4-month period in several habitats, including marsh, irrigation channel, lagoon, and mangrove swamp during the wet season and the wet-dry transition. Dominant plant species in the marsh were Typha dominguensis and Eleocharis mutata. Mesocyclops meridianus also was dominant in the marsh. Highest densities of An. aquasalis larvae, as well as lowest pH values and highest sulfate concentrations, were found in habitats containing E. mutata. Statistical correlation analysis showed that abundances of M. longisetus longisetus and An. aquasalis larvae were positively and significantly correlated in the irrigation channel, and abundances of M. meridianus and An. aquasalis larvae were negatively and significantly correlated in the E. mutata marsh.
Hardy, Andrew J.; Gamarra, Javier G. P.; Cross, Dónall E.; Macklin, Mark G.; Smith, Mark W.; Kihonda, Japhet; Killeen, Gerry F.; Ling’ala, George N.; Thomas, Chris J.
Background Larval source management is a promising component of integrated malaria control and elimination. This requires development of a framework to target productive locations through process-based understanding of habitat hydrology and geomorphology. Methods We conducted the first catchment scale study of fine resolution spatial and temporal variation in Anopheles habitat and productivity in relation to rainfall, hydrology and geomorphology for a high malaria transmission area of Tanzania. Results Monthly aggregates of rainfall, river stage and water table were not significantly related to the abundance of vector larvae. However, these metrics showed strong explanatory power to predict mosquito larval abundances after stratification by water body type, with a clear seasonal trend for each, defined on the basis of its geomorphological setting and origin. Conclusion Hydrological and geomorphological processes governing the availability and productivity of Anopheles breeding habitat need to be understood at the local scale for which larval source management is implemented in order to effectively target larval source interventions. Mapping and monitoring these processes is a well-established practice providing a tractable way forward for developing important malaria management tools. PMID:24312606
Poussart, Pascale F.; Evans, Michael N.; Schrag, Daniel P.
Dendrochronological techniques have found limited applications in the tropics because of invisible or indistinct banding in wood. The seasonal cycles of rainfall and relative humidity in these regions, while not sufficient to produce distinct visible rings, may still generate seasonal signals in the oxygen isotopic composition of tree cellulose which can be used for climate reconstruction and chronology. We explore this approach using trees from Indonesia and Thailand, from three different families. Multi-decade δ 18O records from Javanese cross-dated teak rings and bomb radiocarbon-dated Suar wood lacking visible rings demonstrate the reproducibility of the signal between trees grown at the same locality as well as from wider geographical regions. These results confirm predictions that the trees oxygen isotopic signatures reflect an external climatic forcing. High-resolution δ 18O records reveal large seasonal cycles: up to 4‰ for Javanese Suar samples and up to 18‰ for a Thai Podocarpus sample. We show that the six δ 18O and δ 13C cycles measured on a Podocarpus match the number of growth years for the period spanning the time of wounding and cutting of the wedge section. This result demonstrates that the isotopic cycles found in this tree with indistinct annual rings are indeed seasonal and could be used for chronology. We present evidence that stable isotope chronologies of tropical trees also contain insights in tropical tree physiology and growth dynamics.
Giambelluca, T. W.; Mudd, R. G.; Liu, W.; Kobayashi, N.; Ziegler, A. D.; Miyazawa, Y.; Kumagai, T.; Huang, M.
The Asian Monsoon dominates the climate of the mainland Southeast Asia (MSEA) region, characterized by a highly seasonal rainfall regime in which 80-90% of annual rainfall occurs during the 6-month (May-October) wet season. The accompanying extremes in soil moisture, solar radiation, and vapor pressure deficit exert strong controls on ecosystem fluxes, including evapotranspiration (ET). Rubber (Hevea brasiliensis), the major commercial crop currently replacing traditional agriculture and secondary forests in MSEA is a native of the equatorial Amazon rainforest, and differs physiologically from the dominant native SE Asian forest tree species. It sheds its leaves in the middle of the dry season and flushes new leaves before the onset of the wet season. In some areas, rubber cultivation is suspected of having caused changes in local climate and watershed processes, including a dramatic downward trend in fog frequency and large increases in surface runoff and soil erosion (Wu et al., 2001, Int. J. Sust. Dev. World Ecol. 8:337-345). Guardiola-Claramonte et al. (2008, Ecohydrology 1:13-22; 2010, Ecohydrology 3:306-314) noted striking differences in the timing and rate of dry season root-water extraction under rubber as compared with other vegetation types. To investigate the environmental impacts of rubber, eddy covariance flux towers were installed to monitor energy, water, and carbon exchange at rubber plantation sites in northeastern Thailand and Cambodia. Results of the first two years of observations at the sites indicate that controls on ET differ between wet and dry seasons, with varying responses to energy, soil moisture, canopy wetness, and leaf area. Despite the long dry season and loss of leaves for several weeks, rubber accumulates exceptionally high annual ET totals, exceeding those of natural forest and other plant functional types in the region. The phenology of rubber represents a disruption of the land-atmosphere interactions of native and other non
Pirkola, Sami; Eriksen, Heidi A.; Partonen, Timo; Kieseppä, Tuula; Veijola, Juha; Jääskeläinen, Erika; Mylläri-Figuerola, Eeva-Maija; Salo, Paula M.; Paunio, Tiina
Background In bipolar disorder (BD), seasonality of symptoms is common and disturbances in circadian rhythms have been reported. Objectives We identified high-penetrance families in a geographically restricted area in Northern Fennoscandia and studied the seasonal variation of clinical symptoms among BD subjects and their healthy relatives. Design We explored the clinical characteristics of subjects living in Northern Fennoscandia, with extreme annual variation in daylight. Among known indigenous high-risk families for BD, we compared the affected ones (N=16) with their healthy relatives (N=15), and also included 18 healthy non-related controls from the same geographical area. Seasonal fluctuation in clinical measures was followed up at the 4 most demarcated photoperiodic time points of the annual cycle: around the summer solstice and autumn equinox in 2013, the winter solstice in 2013/2014, and the spring equinox in 2014. In the baseline, lifetime manic symptoms [Mood Disorder Questionnaire (MDQ)] and morningness–eveningness questionnaire type (MEQ) were registered, whereas in the follow-up, depressive [Beck Depression Inventory (BDI)] and distress [General Health Questionnaire (GHQ-12)] symptoms and alcohol consumption and sleep were recorded. Results Possibly indicative or statistically significant differences in symptoms between the affected subjects and their healthy relatives were the BDI winter (13.3 vs. 2.6, t=−2.51, p=0.022) and spring scores (12.6 vs. 3.2, t=−1.97, p=0.063) and GHQ winter (4.2 vs. 0.82, t=−2.08, p=0.052) and spring scores (3.8 vs. 0.82, t=−1.97, p=0.063). Scores were higher among the affected subjects, exceeding a possibly diagnostic threshold (10 and 3) at all the time points, and without the notable seasonality which was observed among the healthy relatives. In the overall population, MDQ and MEQ scores had an inverse correlation (−0.384, significant at 0.016), indicating increased lifetime manic behaviour among “the night
Mordecai, Eerin A.; Paaijmans, Krijin P.; Johnson, Leah R.; Balzer, Christian; Ben-Horin, Tal; de Moor, Emily; McNally, Amy; Pawar, Samraat; Ryan, Sadie J.; Smith, Thomas C.; Lafferty, Kevin D.
The ecology of mosquito vectors and malaria parasites affect the incidence, seasonal transmission and geographical range of malaria. Most malaria models to date assume constant or linear responses of mosquito and parasite life-history traits to temperature, predicting optimal transmission at 31 °C. These models are at odds with field observations of transmission dating back nearly a century. We build a model with more realistic ecological assumptions about the thermal physiology of insects. Our model, which includes empirically derived nonlinear thermal responses, predicts optimal malaria transmission at 25 °C (6 °C lower than previous models). Moreover, the model predicts that transmission decreases dramatically at temperatures > 28 °C, altering predictions about how climate change will affect malaria. A large data set on malaria transmission risk in Africa validates both the 25 °C optimum and the decline above 28 °C. Using these more accurate nonlinear thermal-response models will aid in understanding the effects of current and future temperature regimes on disease transmission.
Albiti, Anisa H; Adam, Ishag; Ghouth, Abdulla S
A cross-sectional study was conducted during the period of August 2007-April 2008 at Al-Wahda Teaching Hospital in Yemen to investigate prevalence and risk factors for placental malaria and anaemia and their effects on birthweight. Sociodemographic characteristics were gathered, maternal haemoglobin was measured and blood films were examined for malaria. Newborn birthweight was recorded. Out of 900 parturient women, malaria blood films were positive in 32 (3.6%) cases: in six sets of peripheral, placental and cord samples; in 15 placental and cord samples; and in 11 placental samples only. Malaria was not associated with age and parity, but it was significantly associated with history of fever [odds ratio (OR) 8.5, 95% CI 3.7-19, P<0.001], rural residence (OR 2.5, 95% CI 1.1-5.3, P=0.01) and rainy season (OR 5.1, 95% CI 1.7-15.2, P=0.003). Overall, 694 (77.1%) out of these 900 women had anaemia (Hb<11g/dl) and 16 (1.8%) patients had severe anaemia (Hb<7g/dl). Anaemia was not associated with age, parity and malaria. Low birthweight was significantly associated with malaria (OR 5.7, 95% CI 1.7-18.5; P=0.004). Thus, preventive measures (bednets and intermittent preventive treatment) should be employed for pregnant women regardless of their age or parity.
Background The importation of malaria to non-endemic countries remains a major cause of travel-related morbidity and a leading cause of travel-related hospitalizations. Currently they are three priority medications for malaria prophylaxis to West Africa: mefloquine, atovaquone/proguanil and doxycycline. We investigate the cost effectiveness of a partial reimbursement of the cheapest effective malaria chemoprophylaxis (mefloquine) for travellers to high risk areas of malaria transmission compared with the current situation of no reimbursement. Methods This study is a cost-effectiveness analysis based on malaria cases imported from West Africa to Switzerland from the perspective of the Swiss health system. We used a decision tree model and made a literature research on the components of travel related malaria. The main outcome measure was the cost effectiveness of malaria chemoprophylaxis reimbursement based on malaria and deaths averted. Results Using a program where travellers would be reimbursed for 80% of the cost of the cheapest malaria chemoprophylaxis is dominant (i.e. cost saving and more effective than the current situation) using the assumption that currently 68.7% of travellers to West Africa use malaria chemoprophylaxis. If the current usage of malaria chemoprophylaxis would be higher, 82.4%, the incremental cost per malaria case averted is € 2'302. The incremental cost of malaria death averted is € 191'833. The most important factors influencing the model were: the proportion of travellers using malaria chemoprophylaxis, the probability of contracting malaria without malaria chemoprophylaxis, the cost of the mefloquine regimen, the decrease in the number of travellers without malaria chemoprophylaxis in the reimbursement strategy. Conclusions This study suggests that a reimbursement of 80% of the cost of the cheapest effective malaria chemoprophylaxis (mefloquine) for travellers from Switzerland to West Africa is highly effective in terms of malaria
Prasad, Anup K; El-Askary, Hesham; Kafatos, Menas
The air over major cities and rural regions of the Nile Delta is highly polluted during autumn which is the biomass burning season, locally known as black cloud. Previous studies have attributed the increased pollution levels during the black cloud season to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. Here we show, for the first time, the evidence of long range transport of dust at high altitude (2.5-6 km) from Western Sahara and its deposition over the Nile Delta region unlike current Models. The desert dust is found to be a major contributor to the local air quality which was previously considered to be due to pollution from biomass burning enhanced by the dominant northerly winds coming from Europe.
Korzeniewski, Krzysztof; Pieruń, Katarzyna
The number of people travelling to regions with hot climate such as Asia, Africa and South America increases steadily every year. The reason for travel varies greatly, from business trips to tourist excursions, the latter definitely prevailing. There has been an increase in travel to destinations where exposure to vector-borne, food- and water-borne, air-borne or sexually transmitted pathogens is common. As one of vector-borne diseases, malaria poses as a serious health hazard to local as well as immigrant populations. Over 40% of the world's inhabitants live in malaria-endemic regions. Although highly developed countries of North America and Europe are generally free from endemic malaria foci, numerous cases of imported infections are observed. Some cases of malaria are also reported in Poland, they are usually brought by persons returning from tropical regions in Africa, Asia, South America, Australia and Oceania. The number of cases depends on the destination as well as on the use or rejection of chemoprophylaxis. The article provides general information on epidemiology, pathogenesis, clinical manifestation and diagnosis of malaria. Emphasis has been put on treatment as well as on chemoprophylaxis of the disease, which are changing relatively quickly, what is mainly related to increasing Plasmodium resistance to applied medicines.
Rodríguez, Julio Cesar Padilla; Uribe, Gilberto Álvarez; Araújo, Roberto Montoya; Narváez, Pablo Chaparro; Valencia, Sócrates Herrera
Malaria is currently one of the most serious public health problems in Colombia with an endemic/epidemic transmission pattern that has maintained endemic levels and an average of 105,000 annual clinical cases being reported over the last five years. Plasmodium vivax accounts for approximately 70% of reported cases with the remainder attributed almost exclusively to Plasmodium falciparum. A limited number of severe and complicated cases have resulted in mortality, which is a downward trend that has been maintained over the last few years. More than 90% of the malaria cases in Colombia are confined to 70 municipalities (about 7% of the total municipalities of Colombia), with high predominance (85%) in rural areas. The purpose of this paper is to review the progress of malaria-eradication activities and control measures over the past century within the eco-epidemiologic context of malaria transmission together with official consolidated morbidity and mortality reports. This review may contribute to the formulation of new antimalarial strategies and policies intended to achieve malaria elimination/eradication in Colombia and in the region. PMID:21881765
Rodríguez, Julio Cesar Padilla; Uribe, Gilberto Álvarez; Araújo, Roberto Montoya; Narváez, Pablo Chaparro; Valencia, Sócrates Herrera
Malaria is currently one of the most serious public health problems in Colombia with an endemic/epidemic transmission pattern that has maintained endemic levels and an average of 105,000 annual clinical cases being reported over the last five years. Plasmodium vivax accounts for approximately 70% of reported cases with the remainder attributed almost exclusively to Plasmodium falciparum. A limited number of severe and complicated cases have resulted in mortality, which is a downward trend that has been maintained over the last few years. More than 90% of the malaria cases in Colombia are confined to 70 municipalities (about 7% of the total municipalities of Colombia), with high predominance (85%) in rural areas. The purpose of this paper is to review the progress of malaria-eradication activities and control measures over the past century within the eco-epidemiologic context of malaria transmission together with official consolidated morbidity and mortality reports. This review may contribute to the formulation of new antimalarial strategies and policies intended to achieve malaria elimination/eradication in Colombia and in the region.
Hedrick, P W
The high mortality and widespread impact of malaria have resulted in this disease being the strongest evolutionary selective force in recent human history, and genes that confer resistance to malaria provide some of the best-known case studies of strong positive selection in modern humans. I begin by reviewing JBS Haldane's initial contribution to the potential of malaria genetic resistance in humans. Further, I discuss the population genetics aspects of many of the variants, including globin, G6PD deficiency, Duffy, ovalocytosis, ABO and human leukocyte antigen variants. Many of the variants conferring resistance to malaria are ‘loss-of-function' mutants and appear to be recent polymorphisms from the last 5000–10 000 years or less. I discuss estimation of selection coefficients from case–control data and make predictions about the change for S, C and G6PD-deficiency variants. In addition, I consider the predicted joint changes when the two β-globin alleles S and C are both variable in the same population and when there is a variation for α-thalassemia and S, two unlinked, but epistatic variants. As more becomes known about genes conferring genetic resistance to malaria in humans, population genetics approaches can contribute both to investigating past selection and predicting the consequences in future generations for these variants. PMID:21427751
Kain, Kevin C
OBJECTIVE: To review the impact of drug-resistant malaria on current management of plasmodial infections. DATA SOURCES: A MEDLINE search of the English-language medical literature from 1985 to 1995; bibliographies of selected papers; international malaria advisory experts. DATA SYNTHESIS: Combinations of artemisinin derivatives and mefloquine or atovaquone plus proguanil appear to be the most active drug regimens against multidrug-resistant falciparum malaria from Southeast Asia. The optimal therapy for chloroquine-resistant Plasmodium vivax is unknown, but recent data indicate that halofantrine or chloroquine plus high doses of primaquine are efficacious. CONCLUSIONS: The incidence of drug-resistant malaria continues to increase at a rate that exceeds new drug development. Ultimately the control of malaria will require more creative approaches than just the development of additional inhibitory drugs. These might include the identification of biochemical pathways unique to the parasite (such as drug efflux and heme polymerization), making it possible to design new classes of antimalarial agents that are selectively toxic to the parasite; methods to block parasite development in the mosquito vector; and multistage vaccines against asexual and sexual stages to block both the pathophysiology and the transmission of disease. PMID:22514413
Schlagenhauf, Patricia; Hatz, Christoph; Behrens, Ron; Visser, Leo; Funk, Maia; Holzer, Benedikt; Beck, Bernhard; Bourquin, Cathérine; Etter, Hermann; Furrer, Hansjakob; Genton, Blaise; Landry, Pierre; Chappuis, Francois; Loutan, Louis; Stössel, Ulrich; Jeschko, Eva; Rossanese, Andrea; Nothdurft, Hans Dieter
Since its introduction to the market in 1985, mefloquine has been used for malaria chemoprophylaxis by more than 35 million travellers. In Europe, in 2014, the European Medicines Agency (EMA) issued recommendations on strengthened warnings, prescribing checklists and updates to the product information of mefloquine. Some malaria prevention advisors question the scientific basis for the restrictions and suggest that this cost-effective, anti-malarial drug will be displaced as a first-line anti-malaria medication with the result that vulnerable groups such as VFR and long-term travellers, pregnant travellers and young children are left without a suitable alternative chemoprophylaxis. This commentary looks at the current position of mefloquine prescribing and the rationale of the new EMA recommendations and restrictions. It also describes the new recommendations for malaria prophylaxis that have been adapted by Switzerland, Germany, Austria and Italy where chemoprophylaxis use is restricted to high-risk malaria-endemic areas.
Clemente, Marina; Corigliano, Mariana G.
This paper is an overview of vaccine antigens against malaria produced in plants. Plant-based expression systems represent an interesting production platform due to their reduced manufacturing costs and high scalability. At present, different Plasmodium antigens and expression strategies have been optimized in plants. Furthermore, malaria antigens are one of the few examples of eukaryotic proteins with vaccine value expressed in plants, making plant-derived malaria antigens an interesting model to analyze. Up to now, malaria antigen expression in plants has allowed the complete synthesis of these vaccine antigens, which have been able to induce an active immune response in mice. Therefore, plant production platforms offer wonderful prospects for improving the access to malaria vaccines. PMID:22911156
Hartjes, Laurie B; Baumann, Linda C
This paper describes a malaria knowledge test (MKT) developed to evaluate a web-based game for students who increasingly travel to malaria-risk regions of the world. The 18-item MKT was structured according to the dimensions of the self-regulation model (SRM) to measure the accuracy of students' beliefs about malaria. An experimental design was used to compare three game versions. Students (N=482) participated in 2010 by completing a pre-test, playing a Web-based game simulating student travel to malaria-endemic destinations, and completing a post-test. Study data support the validity and reliability of the MKT for the evaluation of malaria education interventions and for student self-assessment. Use of the MKT to evaluate an educational game about malaria revealed a strong overall learning effect and discrimination by game version, travel experience, and SRM dimension. This 5-min test may also be adapted for educational outreach purposes among health care providers globally, residents of malaria-endemic regions, and other high risk travel groups (e.g., elderly, chronic health conditions, pregnant, or returning to malaria-endemic regions to visit friends/relatives).
Cheah, Phaik Yeong; Parker, Michael; Dondorp, Arjen M.
Over 90% of deaths attributable to malaria are in African children under 5 years old. Yet, new treatments are often tested primarily in adult patients and extrapolations have proven to be sometimes invalid, especially in dosing regimens. For studies in severe malaria an additional complication is that the decline in severe malaria in adult patients precludes sufficiently powered trials in adults, before the intervention can be tested in the ultimate target group, paediatric severe malaria. In this paper we propose an alternative pathway to the development of drugs for use in paediatric severe malaria. We argue that following the classical phase I and II studies, small safety and efficacy studies using well-chosen surrogate endpoints in adult severe malaria be conducted, instead of larger mortality endpoint trials. If the drug appears safe and promising small pilot studies in paediatric severe malaria using the same endpoints can follow. Finally, with carefully observed safeguards in place to ensure high ethical standards, promising candidate interventions can be taken forward into mortality endpoint, well-powered, large paediatric studies in African children with severe malaria. Given the available research capacity, limited numbers of prudently selected interventions can be studied in phase III trials, and adaptive designs should be considered. PMID:27620923
Longley, Rhea J.; Hill, Adrian V. S.; Spencer, Alexandra J.
The development of a highly efficacious and durable vaccine for malaria remains a top priority for global health researchers. Despite the huge rise in recognition of malaria as a global health problem and the concurrent rise in funding over the past 10–15 years, malaria continues to remain a widespread burden. The evidence of increasing resistance to anti-malarial drugs and insecticides is a growing concern. Hence, an efficacious and durable preventative vaccine for malaria is urgently needed. Vaccines are one of the most cost-effective tools and have successfully been used in the prevention and control of many diseases, however, the development of a vaccine for the Plasmodium parasite has proved difficult. Given the early success of whole sporozoite mosquito-bite delivered vaccination strategies, we know that a vaccine for malaria is an achievable goal, with sub-unit vaccines holding great promise as they are simple and cheap to both manufacture and deploy. However a major difficulty in development of sub-unit vaccines lies within choosing the appropriate antigenic target from the 5000 or so genes expressed by the parasite. Given the liver-stage of malaria represents a bottle-neck in the parasite’s life cycle, there is widespread agreement that a multi-component sub-unit malaria vaccine should preferably contain a liver-stage target. In this article we review progress in identifying and screening Plasmodium falciparum liver-stage targets for use in a malaria vaccine. PMID:26441899
Arnold, N. S.; Banwell, A. F.; Willis, I. C.
Seasonal meltwater lakes on the Greenland Ice Sheet form when surface runoff is temporarily trapped in surface topographic depressions. The development of such lakes affects both the surface energy balance and dynamics of the ice sheet. Although areal extents, depths and lifespan of lakes can be inferred from satellite imagery, such observational studies have a limited temporal resolution. Here, we adopt a modelling-based strategy to estimate the seasonal evolution of surface water storage for the ~ 3600 km2 Paakitsoq region of W. Greenland. We use a high-resolution time-dependent surface mass balance model to calculate surface melt, a supraglacial water routing model to calculate lake filling and a prescribed water-volume-based threshold to predict rapid lake drainage events. This threshold assumes that drainage will occur through a fracture if V = Fa ⋅ H, where V is lake volume, H is the local ice thickness and Fa is the potential fracture area. The model shows good agreement between modelled lake locations and volumes and those observed in nine Landsat 7 ETM images from 2001, 2002 and 2005. We use the model to investigate the lake water volume required to trigger drainage, and the impact that varying this threshold volume has on the proportion of meltwater that is stored in surface lakes and enters the subglacial drainage system. Model performance is maximised with values of Fa between 4000 and 7500 m2. For these thresholds, lakes transiently store < 40% of available meltwater at the beginning of the melt season, decreasing to ~ 5 to 10% by the middle of the melt season; over the course of a melt season, 40 to 50% of total meltwater production enters the subglacial drainage system through moulins at the bottom of drained lakes.
Wimberly, M. C.; Merkord, C. L.; Henebry, G. M.; Senay, G. B.
Early warning of the timing and locations of malaria epidemics can facilitate the targeting of resources for prevention and emergency response. In response to this need, we are developing the Epidemic Prognosis Incorporating Disease and Environmental Monitoring for Integrated Assessment (EPIDEMIA) computer system. EPIDEMIA incorporates software for capturing, processing, and integrating environmental and epidemiological data from multiple sources; data assimilation techniques that continually update models and forecasts; and a web-based interface that makes the resulting information available to public health decision makers. The system will enable forecasts that incorporate lagged responses to environmental risk factors as well as information about recent trends in malar