Integrated vector management: a critical strategy for combating vector-borne diseases in South Sudan

PubMed Central

2013-01-01

Background Integrated vector management (IVM) based vector control is encouraged by the World Health Organization (WHO). However, operational experience with the IVM strategy has mostly come from countries with relatively well-established health systems and with malaria control focused programmes. Little is known about deployment of IVM for combating multiple vector-borne diseases in post-emergency settings, where delivery structures are less developed or absent. This manuscript reports on the feasibility of operational IVM for combating vector-borne diseases in South Sudan. Case description A methodical review of published and unpublished documents on vector-borne diseases for South Sudan was conducted via systematic literature search of online electronic databases, Google Scholar, PubMed and WHO, using a combination of search terms. Additional, non-peer reviewed literature was examined for information related to the subject. Discussion South Sudan is among the heartlands of vector-borne diseases in the world, characterized by enormous infrastructure, human and financial resource constraints and a weak health system against an increasing number of refugees, returnees and internally displaced people. The presence of a multiplicity of vector-borne diseases in this post-conflict situation presents a unique opportunity to explore the potential of a rational IVM strategy for multiple disease control and optimize limited resource utilization, while maximizing the benefits and providing a model for countries in a similar situation. Conclusion The potential of integrating vector-borne disease control is enormous in South Sudan. However, strengthened coordination, intersectoral collaboration and institutional and technical capacity for entomological monitoring and evaluation, including enforcement of appropriate legislation are crucial. PMID:24156749

Intestinal parasites and vector-borne pathogens in stray and free-roaming cats living in continental and insular Greece

PubMed Central

Diakou, Anastasia; Di Cesare, Angela; Accettura, Paolo Matteo; Barros, Luciano; Iorio, Raffaella; Paoletti, Barbara; Frangipane di Regalbono, Antonio; Halos, Lénaïg; Beugnet, Frederic; Traversa, Donato

2017-01-01

This survey investigated the distribution of various intestinal parasites and vector-borne pathogens in stray and free-roaming cats living in four regions of Greece. A total number of one hundred and fifty cats living in three Islands (Crete, Mykonos and Skopelos) and in Athens municipality was established as a realistic aim to be accomplished in the study areas. All cats were examined with different microscopic, serological and molecular assays aiming at evaluating the occurrence of intestinal parasites, and exposure to or presence of vector-borne infections. A total of 135 cats (90%) was positive for one or more parasites and/or pathogens transmitted by ectoparasites. Forty-four (29.3%) cats were positive for one single infection, while 91 (60.7%) for more than one pathogen. A high number of (n. 53) multiple infections caused by feline intestinal and vector-borne agents including at least one zoonotic pathogen was detected. Among them, the most frequently recorded helminths were roundworms (Toxocara cati, 24%) and Dipylidium caninum (2%), while a high number of examined animals (58.8%) had seroreaction for Bartonella spp., followed by Rickettsia spp. (43.2%) and Leishmania infantum (6.1%). DNA-based assays revealed the zoonotic arthropod-borne organisms Bartonella henselae, Bartonella clarridgeiae, Rickettsia spp., and L. infantum. These results show that free-ranging cats living in areas of Greece under examination may be exposed to a plethora of internal parasites and vector-borne pathogens, some of them potentially able to infect humans. Therefore, epidemiological vigilance and appropriate control measures are crucial for the prevention and control of these infections and to minimize the risk of infection for people. PMID:28141857

Intestinal parasites and vector-borne pathogens in stray and free-roaming cats living in continental and insular Greece.

PubMed

Diakou, Anastasia; Di Cesare, Angela; Accettura, Paolo Matteo; Barros, Luciano; Iorio, Raffaella; Paoletti, Barbara; Frangipane di Regalbono, Antonio; Halos, Lénaïg; Beugnet, Frederic; Traversa, Donato

2017-01-01

This survey investigated the distribution of various intestinal parasites and vector-borne pathogens in stray and free-roaming cats living in four regions of Greece. A total number of one hundred and fifty cats living in three Islands (Crete, Mykonos and Skopelos) and in Athens municipality was established as a realistic aim to be accomplished in the study areas. All cats were examined with different microscopic, serological and molecular assays aiming at evaluating the occurrence of intestinal parasites, and exposure to or presence of vector-borne infections. A total of 135 cats (90%) was positive for one or more parasites and/or pathogens transmitted by ectoparasites. Forty-four (29.3%) cats were positive for one single infection, while 91 (60.7%) for more than one pathogen. A high number of (n. 53) multiple infections caused by feline intestinal and vector-borne agents including at least one zoonotic pathogen was detected. Among them, the most frequently recorded helminths were roundworms (Toxocara cati, 24%) and Dipylidium caninum (2%), while a high number of examined animals (58.8%) had seroreaction for Bartonella spp., followed by Rickettsia spp. (43.2%) and Leishmania infantum (6.1%). DNA-based assays revealed the zoonotic arthropod-borne organisms Bartonella henselae, Bartonella clarridgeiae, Rickettsia spp., and L. infantum. These results show that free-ranging cats living in areas of Greece under examination may be exposed to a plethora of internal parasites and vector-borne pathogens, some of them potentially able to infect humans. Therefore, epidemiological vigilance and appropriate control measures are crucial for the prevention and control of these infections and to minimize the risk of infection for people.

Epidemiological Scenario of Dengue in Brazil

PubMed Central

2015-01-01

Dengue is the most important reemerging mosquito-borne viral disease worldwide. It is caused by any of four Dengue virus types or serotypes (DENV-1 to DENV-4) and is transmitted by mosquitoes from the genus Aedes. Ecological changes have favored the geographic expansion of the vector and, since the dengue pandemic in the Asian and Pacific regions, the infection became widely distributed worldwide, reaching Brazil in 1845. The incidence of dengue in Brazil has been frequently high, and the number of cases in the country has at some point in time represented up to 60% of the dengue reported cases worldwide. This review addresses vector distribution, dengue outbreaks, circulating serotypes and genotypes, and prevention approaches being utilized in Brazil. PMID:26413514

Major vectors and vector-borne diseases in small ruminants in Ethiopia: A systematic review.

PubMed

Asmare, Kassahun; Abayneh, Takele; Sibhat, Berhanu; Shiferaw, Dessie; Szonyi, Barbara; Krontveit, Randi I; Skjerve, Eystein; Wieland, Barbara

2017-06-01

Vector-borne diseases are among major health constraints of small ruminant in Ethiopia. While various studies on single vector-borne diseases or presence of vectors have been conducted, no summarized evidence is available on the occurrence of these diseases and the related vectors. This systematic literature review provides a comprehensive summary on major vectors and vector-borne diseases in small ruminants in Ethiopia. Search for published and unpublished literature was conducted between 8th of January and 25th of June 2015. The search was both manual and electronic. The databases used in electronic search were PubMed, Web of Science, CAB Direct and AJOL. For most of the vector-borne diseases, the summary was limited to narrative synthesis due to lack of sufficient data. Meta-analysis was computed for trypanosomosis and dermatophilosis while meta-regression and sensitivity analysis was done only for trypanososmosis due to lack of sufficient reports on dermatophilosis. Owing emphasis to their vector role, ticks and flies were summarized narratively at genera/species level. In line with inclusion criteria, out of 106 initially identified research reports 43 peer-reviewed articles passed the quality assessment. Data on 7 vector-borne diseases were extracted at species and region level from each source. Accordingly, the pooled prevalence estimate of trypanosomosis was 3.7% with 95% confidence interval (CI) 2.8, 4.9), while that of dermatophilosis was 3.1% (95% CI: 1.6, 6.0). The in-between study variance noted for trypanosomosis was statistically significant (p<0.05). Among the three covariates considered for meta-regression, only one (species) fitted the final model significantly (p<0.05) and explained 65.44% of the between studies variance (R 2 ). The prevalence in sheep (5.5%) increased nearly by 34% compared to goats (2.9%). The parasitic presence in blood was documented for babesiosis (3.7% in goats); and anaplasmosis (3.9% in sheep). Serological evidence was retrieved for bluetongue ranging from 34.1% to 46.67% in sheep, and coxiellosis was 10.4% in goats. There was also molecular evidence on the presence of theileriosis in sheep (93%, n=160) and goats (1.9%, n=265). Regarding vectors of veterinary importance, 14 species of ticks in five genera, four species of Glossina and 4 genera of biting flies were reported. Despite the evidence on presence of various vectors including ticks, flies, mosquitoes and midges, studies on vector-borne diseases in Ethiopia are surprisingly rare, especially considering risks related to climate change, which is likely to affect distribution of vectors. Thus better evidence on the current situation is urgently needed in order to prevent spread and to model future distribution scenarios. Copyright © 2017 Elsevier B.V. All rights reserved.

Gray Wolf Exposure to Emerging Vector-Borne Diseases in Wisconsin with Comparison to Domestic Dogs and Humans

PubMed Central

Jara, Rocio F.; Wydeven, Adrian P.; Samuel, Michael D.

2016-01-01

World-wide concern over emerging vector-borne diseases has increased in recent years for both animal and human health. In the United Sates, concern about vector-borne diseases in canines has focused on Lyme disease, anaplasmosis, ehrlichiosis, and heartworm which infect domestic and wild canids. Of these diseases, Lyme and anaplasmosis are also frequently diagnosed in humans. Gray wolves (Canis lupus) recolonized Wisconsin in the 1970s, and we evaluated their temporal and geographic patterns of exposure to these four vector-borne diseases in Wisconsin as the population expanded between 1985 and 2011. A high proportion of the Wisconsin wolves were exposed to the agents that cause Lyme (65.6%) and anaplasma (47.7%), and a smaller proportion to ehrlichiosis (5.7%) and infected with heartworm (9.2%). Wolf exposure to tick borne diseases was consistently higher in older animals. Wolf exposure was markedly higher than domestic dog (Canis familiaris) exposure for all 4 disease agents during 2001–2013. We found a cluster of wolf exposure to Borrelia burgdorferi in northwestern Wisconsin, which overlaps human and domestic dog clusters for the same pathogen. In addition, wolf exposure to Lyme disease in Wisconsin has increased, corresponding with the increasing human incidence of Lyme disease in a similar time period. Despite generally high prevalence of exposure none of these diseases appear to have slowed the growth of the Wisconsin wolf population. PMID:27898670

Vector-Borne Infections in Tornado-Displaced and Owner-Relinquished Dogs in Oklahoma, USA.

PubMed

Barrett, Anne W; Little, Susan E

2016-06-01

To determine the prevalence of infection with vector-borne agents in a cross-section of dogs from Oklahoma, where canine vector-borne diseases are common, blood samples were evaluated through serology and molecular analysis. Antibodies reactive to Ehrlichia spp., Rickettsia rickettsii, R. montanensis, and "R. amblyommii" were detected in 10.5% (11/105), 74.3% (78/105), 58.1% (61/105), and 55.2% (58/105) of dogs, respectively. Presence of spotted fever group Rickettsia spp. DNA was identified in 13.1% (8/61) of shelter dogs but not in any pet dogs (0/44). DNA of "R. amblyommii" was confirmed by sequencing, constituting the first report of this agent in a naturally infected dog. Antigen of Dirofilaria immitis was detected in 10.5% (11/105) and 16.2% (17/105) of samples before and after heat treatment, respectively. In total, 87.6% (92/105) of the dogs had evidence of infection with at least one vector-borne disease agent, confirming high risk of exposure to multiple vector-borne disease agents, several of which are zoonotic.

Parasites and vector-borne pathogens in client-owned dogs in Albania. Blood pathogens and seroprevalences of parasitic and other infectious agents.

PubMed

Hamel, Dietmar; Shukullari, Enstela; Rapti, Dhimitër; Silaghi, Cornelia; Pfister, Kurt; Rehbein, Steffen

2016-02-01

Knowledge on the epidemiology of parasitic and vector-borne infections is still very limited for Albania, a country located in the Balkan Peninsula in southeast Europe. Recent publications indicated prevalence rates of up to 52% for vector-borne infections in less-cared dogs in Albania. To provide data on the epidemiological situation in dogs under veterinary care, a total of 602 client-owned dogs presented to four small animal clinics between March 2010 and April 2011 in Tirana, Albania, were screened by examination of Giemsa-stained blood smears, PCR, and serological methods for the presence of arthropod-borne infections, as well as Neospora caninum and Toxoplasma gondii. Eight different pathogens, namely Babesia vogeli, Hepatozoon canis, Leishmania infantum, Dirofilaria immitis, Anaplasma phagocytophilum, Anaplasma platys, Ehrlichia canis, and Mycoplasma haemocanis, were detected by direct methods with prevalence rates ranging from 1 to 9%. Seroprevalence for Babesia spp., L. infantum, Anaplasma spp., and E. canis were 6.6, 5.1, 24.1, and 20.8%, respectively. Dogs >1 year of age were positive for vector-borne infections significantly more often than younger dogs (p = 0.003). More than half (51.7%) of the dogs were seroreactive to T. gondii and 18.3% to N. caninum. This is the first report on the detection of A. phagocytophilum, A. platys, E. canis, and M. haemocanis by PCR as well as the serological confirmation of exposure of dogs to N. caninum and T. gondii in Albania. The spectrum of pathogens and the seroprevalences for N. caninum and T. gondii in client-owned dogs from Tirana, Albania, are comparable to that reported in other countries in the Mediterranean Basin. The prevalence rates of vector-borne pathogens are at the lower range of that reported in studies from this geographical region. This is probably due to increased awareness of the owners of pet dogs, including better husbandry conditions and ectoparasiticidal treatment, thus limiting exposure of dogs to vectors.

Disaggregating tropical disease prevalence by climatic and vegetative zones within tropical West Africa

USDA-ARS?s Scientific Manuscript database

Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions...

Early effects of climate change: do they include changes in vector-borne disease?

PubMed Central

Kovats, R S; Campbell-Lendrum, D H; McMichael, A J; Woodward, A; Cox, J S

2001-01-01

The world's climate appears now to be changing at an unprecedented rate. Shifts in the distribution and behaviour of insect and bird species indicate that biological systems are already responding to this change. It is well established that climate is an important determinant of the spatial and temporal distribution of vectors and pathogens. In theory, a change in climate would be expected to cause changes in the geographical range, seasonality (intra-annual variability), and in the incidence rate (with or without changes in geographical or seasonal patterns). The detection and then attribution of such changes to climate change is an emerging task for scientists. We discuss the evidence required to attribute changes in disease and vectors to the early effects of anthropogenic climate change. The literature to date indicates that there is a lack of strong evidence of the impact of climate change on vector-borne diseases (i.e. malaria, dengue, leishmaniasis, tick-borne diseases). New approaches to monitoring, such as frequent and long-term sampling along transects to monitor the full latitudinal and altitudinal range of specific vector species, are necessary in order to provide convincing direct evidence of climate change effects. There is a need to reassess the appropriate levels of evidence, including dealing with the uncertainties attached to detecting the health impacts of global change. PMID:11516383

Exposure to vector-borne pathogens in candidate blood donor and free-roaming dogs of northeast Italy.

PubMed

Vascellari, Marta; Ravagnan, Silvia; Carminato, Antonio; Cazzin, Stefania; Carli, Erika; Da Rold, Graziana; Lucchese, Laura; Natale, Alda; Otranto, Domenico; Capelli, Gioia

2016-06-29

Many vector-borne pathogens including viruses, bacteria, protozoa and nematodes occur in northeast Italy, representing a potential threat to animal and human populations. Little information is available on the circulation of the above vector-borne pathogens in dogs. This work aims to (i) assess exposure to and circulation of pathogens transmitted to dogs in northeast Italy by ticks, sandflies, and mosquitoes, and (ii) drive blood donor screening at the newly established canine blood bank of the Istituto Zooprofilattico Sperimentale delle Venezie. Blood samples from 150 privately-owned canine candidate blood donors and 338 free-roaming dogs were screened by serology (IFA for Leishmania infantum, Ehrlichia canis, Anaplasma phagocythophilum, Babesia canis, Rickettsia conorii, R. rickettsii), microscopic blood smear examination, and blood filtration for Dirofilaria spp. All candidate donors and seropositive free-roaming dogs were tested by PCR for L. infantum, E. canis, A. phagocythophilum, Babesia/Theileria and Rickettsia spp. The dogs had no clinical signs at the time of sampling. Overall, 40 candidate donors (26.7 %) and 108 free-roaming dogs (32 %) were seroreactive to at least one vector-borne pathogen. Seroprevalence in candidate donors vs free-roaming dogs was: Leishmania infantum 6.7 vs 7.1 %; Anaplasma phagocytophilum 4.7 vs 3.3 %; Babesia canis 1.3 vs 2.7 %; Ehrlichia canis none vs 0.9 %; Rickettsia conorii 16 vs 21.3 % and R. rickettsii 11 vs 14.3 %. Seroreactivity to R. rickettsii, which is not reported in Italy, is likely a cross-reaction with other rickettsiae. Filariae, as Dirofilaria immitis (n = 19) and D. repens (n = 2), were identified in free-roaming dogs only. No significant differences were observed between candidate donors and free-roaming dogs either in the overall seroprevalence of vector-borne pathogens or for each individual pathogen. All PCRs and smears performed on blood were negative. This study demonstrated that dogs are considerably exposed to vector-borne pathogens in northeast Italy. Although the dog owners reported regularly using ectoparasiticides against fleas and ticks, their dogs had similar exposure to vector-borne pathogens as free-roaming dogs. This prompts the need to improve owner education on the use of insecticidal and repellent compounds in order to reduce the risk of arthropod bites and exposure to vector-borne pathogens. Based on the absence of pathogens circulating in the blood of healthy dogs, the risk of transmission of these pathogens by blood transfusion seems to be low, depending also on the sensitivity of the tests used for screening.

Disaggregating tropical disease prevalence by climatic and vegetative zones within tropical west Africa

Treesearch

Carl S. Beckley; Salisu Shaban; Guy H. Palmer; Andrew T. Hudak; Susan M. Noh; James E. Futse

2016-01-01

Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly...

Vector-borne diseases of small companion animals in Namibia: Literature review, knowledge gaps and opportunity for a One Health approach.

PubMed

Noden, Bruce H; Soni, Minty

2015-11-06

Namibia has a rich history in veterinary health but little is known about the vector-borne diseases that affect companion dogs and cats. The aim of this review is to summarise the existing published and available unpublished literature, put it into a wider geographical context, and explore some significant knowledge gaps. To date, only two filarial pathogens (Dirofilaria repens and Acanthocheilonema dracunculoides) and three tick-borne pathogens (Babesia canis vogeli, Hepatozoon canis and Ehrlichia canis) have been reported. Most studies have focused solely on dogs and cats in the urban Windhoek and surrounding areas, with almost nothing reported in rural farming areas, in either the populous northern regions or the low-income urban areas where animal owners have limited access to veterinary services. With the development of several biomedical training programmes in the country, there is now an excellent opportunity to address zoonotic vector-borne diseases through a One Health approach so as to assess the risks to small companion animals as well as diseases of public health importance.

Mechanisms of double-strand-break repair during gene targeting in mammalian cells.

PubMed Central

Ng, P; Baker, M D

1999-01-01

In the present study, the mechanism of double-strand-break (DSB) repair during gene targeting at the chromosomal immunoglobulin mu-locus in a murine hybridoma was examined. The gene-targeting assay utilized specially designed insertion vectors genetically marked in the region of homology to the chromosomal mu-locus by six diagnostic restriction enzyme site markers. The restriction enzyme markers permitted the contribution of vector-borne and chromosomal mu-sequences in the recombinant product to be determined. The use of the insertion vectors in conjunction with a plating procedure in which individual integrative homologous recombination events were retained for analysis revealed several important features about the mammalian DSB repair process:The presence of the markers within the region of shared homology did not affect the efficiency of gene targeting.In the majority of recombinants, the vector-borne marker proximal to the DSB was absent, being replaced with the corresponding chromosomal restriction enzyme site. This result is consistent with either formation and repair of a vector-borne gap or an "end" bias in mismatch repair of heteroduplex DNA (hDNA) that favored the chromosomal sequence. Formation of hDNA was frequently associated with gene targeting and, in most cases, began approximately 645 bp from the DSB and could encompass a distance of at least 1469 bp.The hDNA was efficiently repaired prior to DNA replication.The repair of adjacent mismatches in hDNA occurred predominantly on the same strand, suggesting the involvement of a long-patch repair mechanism. PMID:10049929

Global climate change and its potential impact on disease transmission by salinity-tolerant mosquito vectors in coastal zones.

PubMed

Ramasamy, Ranjan; Surendran, Sinnathamby Noble

2012-01-01

Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5 ppt or parts per thousand, 0.5-30 ppt and >30 ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross-McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for increased coastal transmission of mosquito-borne diseases consequent to climate change and a rise in sea levels. It is proposed that the Jaffna peninsula in Sri Lanka may be a useful case study for the impact of rising sea levels on mosquito vectors in tropical coasts.

Global Climate Change and Its Potential Impact on Disease Transmission by Salinity-Tolerant Mosquito Vectors in Coastal Zones

PubMed Central

Ramasamy, Ranjan; Surendran, Sinnathamby Noble

2012-01-01

Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5 ppt or parts per thousand, 0.5–30 ppt and >30 ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross–McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for increased coastal transmission of mosquito-borne diseases consequent to climate change and a rise in sea levels. It is proposed that the Jaffna peninsula in Sri Lanka may be a useful case study for the impact of rising sea levels on mosquito vectors in tropical coasts. PMID:22723781

The role of remote sensing and GIS for spatial prediction of vector-borne diseases transmission: a systematic review.

PubMed

Palaniyandi, M

2012-12-01

There have been several attempts made to the appreciation of remote sensing and GIS for the study of vectors, biodiversity, vector presence, vector abundance and the vector-borne diseases with respect to space and time. This study was made for reviewing and appraising the potential use of remote sensing and GIS applications for spatial prediction of vector-borne diseases transmission. The nature of the presence and the abundance of vectors and vector-borne diseases, disease infection and the disease transmission are not ubiquitous and are confined with geographical, environmental and climatic factors, and are localized. The presence of vectors and vector-borne diseases is most complex in nature, however, it is confined and fueled by the geographical, climatic and environmental factors including man-made factors. The usefulness of the present day availability of the information derived from the satellite data including vegetation indices of canopy cover and its density, soil types, soil moisture, soil texture, soil depth, etc. is integrating the information in the expert GIS engine for the spatial analysis of other geoclimatic and geoenvironmental variables. The present study gives the detailed information on the classical studies of the past and present, and the future role of remote sensing and GIS for the vector-borne diseases control. The ecological modeling directly gives us the relevant information to understand the spatial variation of the vector biodiversity, vector presence, vector abundance and the vector-borne diseases in association with geoclimatic and the environmental variables. The probability map of the geographical distribution and seasonal variations of horizontal and vertical distribution of vector abundance and its association with vector -borne diseases can be obtained with low cost remote sensing and GIS tool with reliable data and speed.

Assessment of Climate Change and Vector-borne Diseases in the United States

NASA Astrophysics Data System (ADS)

Monaghan, A. J.; Beard, C. B.; Eisen, R. J.; Barker, C. M.; Garofalo, J.; Hahn, M.; Hayden, M.; Ogden, N.; Schramm, P.

2016-12-01

Vector-borne diseases are illnesses that are transmitted by vectors, which include mosquitoes, ticks, and fleas. The seasonality, distribution, and prevalence of vector-borne diseases are influenced significantly by climate factors, primarily high and low temperature extremes and precipitation patterns. In this presentation we summarize key findings from Chapter 5 ("Vector-borne Diseases") of the recently published USGCRP Scientific Assessment of the Impacts of Climate Change on Human Health in the United States. Climate change is expected to alter geographic and seasonal distributions of vectors and vector-borne diseases, leading to earlier activity and northward range expansion of ticks capable of carrying the bacteria that cause Lyme disease and other pathogens, and influencing the distribution, abundance and prevalence of infection in mosquitoes that transmit West Nile virus and other pathogens. The emergence or reemergence of vector-borne pathogens is also likely.

Spatial disaggregation of tick occurrence and ecology at a local scale as a preliminary step for spatial surveillance of tick-borne diseases: general framework and health implications in Belgium.

PubMed

Obsomer, Valerie; Wirtgen, Marc; Linden, Annick; Claerebout, Edwin; Heyman, Paul; Heylen, Dieter; Madder, Maxime; Maris, Jo; Lebrun, Maude; Tack, Wesley; Lempereur, Laetitia; Hance, Thierry; Van Impe, Georges

2013-06-22

The incidence of tick-borne diseases is increasing in Europe. Sub national information on tick distribution, ecology and vector status is often lacking. However, precise location of infection risk can lead to better targeted prevention measures, surveillance and control. In this context, the current paper compiled geolocated tick occurrences in Belgium, a country where tick-borne disease has received little attention, in order to highlight the potential value of spatial approaches and draw some recommendations for future research priorities. Mapping of 89,289 ticks over 654 sites revealed that ticks such as Ixodes ricinus and Ixodes hexagonus are largely present while Dermacentor reticulatus has a patchy distribution. Suspected hot spots of tick diversity might favor pathogen exchanges and suspected hot spots of I. ricinus abundance might increase human-vector contact locally. This underlines the necessity to map pathogens and ticks in detail. While I. ricinus is the main vector, I. hexagonus is a vector and reservoir of Borrelia burgdorferi s.l., which is active the whole year and is also found in urban settings. This and other nidiculous species bite humans less frequently, but seem to harbour pathogens. Their role in maintaining a pathogenic cycle within the wildlife merits investigation as they might facilitate transmission to humans if co-occurring with I. ricinus. Many micro-organisms are found abroad in tick species present in Belgium. Most have not been recorded locally but have not been searched for. Some are transmitted directly at the time of the bite, suggesting promotion of tick avoidance additionally to tick removal. This countrywide approach to tick-borne diseases has helped delineate recommendations for future research priorities necessary to design public health policies aimed at spatially integrating the major components of the ecological cycle of tick-borne diseases. A systematic survey of tick species and associated pathogens is called for in Europe, as well as better characterisation of species interaction in the ecology of tick-borne diseases, those being all tick species, pathogens, hosts and other species which might play a role in tick-borne diseases complex ecosystems.

Climate change and cattle vector-borne diseases: Use of participatory epidemiology to investigate experiences in pastoral communities in Northern Tanzania.

PubMed

Kimaro, Esther G; Toribio, Jenny-Ann L M L; Mor, Siobhan M

2017-11-01

Climate change is predicted to increase incidence of vector-borne diseases in humans, however, little is known about the impact of such diseases in livestock. In the absence of historical data with which to examine the inter-relation between climate and disease, participatory epidemiological (PE) methods were used with Maasai pastoralists of Monduli District, northern Tanzania to establish local observations on two major vector-borne diseases of cattle, namely East Coast fever (ECF) and African animal trypanosomiasis (AAT). Data collection involving gender segregated groups (10 men groups and 9 women groups) occurred in 10 randomly selected villages between November 2014 and March 2015. ECF and AAT were ranked amongst the top 5 most important cattle diseases with strong agreement across informant groups (Kendall's W=0.40 for men and 0.45 for women; p<0.01). Matrix scoring for both men and women groups confirmed that Masaai easily recognize these diseases. All groups associated ECF with the wet and cool dry seasons. AAT was more variable throughout the year, with more cases reported in the long dry season. Likewise, pastoralists reported differences in seasonal occurrence of disease vectors (Rhipicephalus appendiculatus and Glossina spp.) by village. Comparing 2014-1984, participant groups consistently reported declines in rainfall, vegetation cover and quality pasture, as well as increases in severe droughts. Experiences with ECF/AAT and vector abundance between these time periods was more variable across villages, and likely relates to changes in climate and animal management practices over the last 30 years. This baseline study is the first to document the inter-relation between climate and cattle vector-borne disease from the pastoralist perspective. Findings from this study reveal a complex interplay between human, animal and environmental factors, understanding of which is urgently required to devise approaches to mitigate effects of climate change in these vulnerable areas. Copyright © 2017 Elsevier B.V. All rights reserved.

Vector-Borne Bacterial Plant Pathogens: Interactions with Hemipteran Insects and Plants

PubMed Central

Perilla-Henao, Laura M.; Casteel, Clare L.

2016-01-01

Hemipteran insects are devastating pests of crops due to their wide host range, rapid reproduction, and ability to transmit numerous plant-infecting pathogens as vectors. While the field of plant–virus–vector interactions has flourished in recent years, plant–bacteria–vector interactions remain poorly understood. Leafhoppers and psyllids are by far the most important vectors of bacterial pathogens, yet there are still significant gaps in our understanding of their feeding behavior, salivary secretions, and plant responses as compared to important viral vectors, such as whiteflies and aphids. Even with an incomplete understanding of plant–bacteria–vector interactions, some common themes have emerged: (1) all known vector-borne bacteria share the ability to propagate in the plant and insect host; (2) particular hemipteran families appear to be incapable of transmitting vector-borne bacteria; (3) all known vector-borne bacteria have highly reduced genomes and coding capacity, resulting in host-dependence; and (4) vector-borne bacteria encode proteins that are essential for colonization of specific hosts, though only a few types of proteins have been investigated. Here, we review the current knowledge on important vector-borne bacterial pathogens, including Xylella fastidiosa, Spiroplasma spp., Liberibacter spp., and ‘Candidatus Phytoplasma spp.’. We then highlight recent approaches used in the study of vector-borne bacteria. Finally, we discuss the application of this knowledge for control and future directions that will need to be addressed in the field of vector–plant–bacteria interactions. PMID:27555855

Brave New Worlds: The Expanding Universe of Lyme Disease.

PubMed

Stone, Brandee L; Tourand, Yvonne; Brissette, Catherine A

2017-09-01

Projections around the globe suggest an increase in tick-vectored disease incidence and distribution, and the potential for emergence of novel tick-borne pathogens. Lyme disease is the most common reported tick-borne illness in the Unites States and is prevalent throughout much of central Europe. In recent years, the worldwide burden of Lyme disease has increased and extended into regions and countries where the disease was not previously reported. In this review, we discuss the trends for increasing Lyme disease, and examine the factors driving Lyme disease expansion, including the effect of climate change on the spread of vector Ixodid ticks and reservoir hosts; and the impacts of increased awareness on disease reporting and diagnosis. To understand the growing threat of Lyme disease, we need to study the interplay between vector, reservoir, and pathogen. In addition, we need to understand the contributions of climate conditions to changes in disease risk.

Predictiveness of Disease Risk in a Global Outreach Tourist Setting in Thailand Using Meteorological Data and Vector-Borne Disease Incidences

PubMed Central

Ninphanomchai, Suwannapa; Chansang, Chitti; Hii, Yien Ling; Rocklöv, Joacim; Kittayapong, Pattamaporn

2014-01-01

Dengue and malaria are vector-borne diseases and major public health problems worldwide. Changes in climatic factors influence incidences of these diseases. The objective of this study was to investigate the relationship between vector-borne disease incidences and meteorological data, and hence to predict disease risk in a global outreach tourist setting. The retrospective data of dengue and malaria incidences together with local meteorological factors (temperature, rainfall, humidity) registered from 2001 to 2011 on Koh Chang, Thailand were used in this study. Seasonal distribution of disease incidences and its correlation with local climatic factors were analyzed. Seasonal patterns in disease transmission differed between dengue and malaria. Monthly meteorological data and reported disease incidences showed good predictive ability of disease transmission patterns. These findings provide a rational basis for identifying the predictive ability of local meteorological factors on disease incidence that may be useful for the implementation of disease prevention and vector control programs on the tourism island, where climatic factors fluctuate. PMID:25325356

Predictiveness of disease risk in a global outreach tourist setting in Thailand using meteorological data and vector-borne disease incidences.

PubMed

Ninphanomchai, Suwannapa; Chansang, Chitti; Hii, Yien Ling; Rocklöv, Joacim; Kittayapong, Pattamaporn

2014-10-16

Dengue and malaria are vector-borne diseases and major public health problems worldwide. Changes in climatic factors influence incidences of these diseases. The objective of this study was to investigate the relationship between vector-borne disease incidences and meteorological data, and hence to predict disease risk in a global outreach tourist setting. The retrospective data of dengue and malaria incidences together with local meteorological factors (temperature, rainfall, humidity) registered from 2001 to 2011 on Koh Chang, Thailand were used in this study. Seasonal distribution of disease incidences and its correlation with local climatic factors were analyzed. Seasonal patterns in disease transmission differed between dengue and malaria. Monthly meteorological data and reported disease incidences showed good predictive ability of disease transmission patterns. These findings provide a rational basis for identifying the predictive ability of local meteorological factors on disease incidence that may be useful for the implementation of disease prevention and vector control programs on the tourism island, where climatic factors fluctuate.

Borrelia miyamotoi, Other Vector-Borne Agents in Cat Blood and Ticks in Eastern Maryland.

PubMed

Shannon, Avery B; Rucinsky, Renee; Gaff, Holly D; Brinkerhoff, R Jory

2017-12-01

We collected blood and tick samples in eastern Maryland to quantify vector-borne pathogen exposure and infection in healthy cats and to assess occupational disease risk to veterinary professionals and others who regularly interact with household pets. Thirty-six percent of healthy cats parasitized by ticks at time of examination (9/25) were exposed to, and 14% of bloods (7/49) tested PCR-positive for, at least one vector-borne pathogen including several bloods and ticks with Borrelia miyamotoi, a recently recognized tick-borne zoonotic bacterium. There was no indication that high tick burdens were associated with exposure to vector-borne pathogens. Our results underscore the potential importance of cats to human vector-borne disease risk.

Vector-borne pathogens: New and emerging arboviral diseases affecting public health

USDA-ARS?s Scientific Manuscript database

Dengue and Zika have quickly become two of the most important vector-borne diseases affecting Public health around the world. This presentation will introduce vector-borne diseases and all the vectors implicated. A focus will be made on the most important arboviral diseases (Zika and dengue) describ...

A network-patch methodology for adapting agent-based models for directly transmitted disease to mosquito-borne disease.

PubMed

Manore, Carrie A; Hickmann, Kyle S; Hyman, James M; Foppa, Ivo M; Davis, Justin K; Wesson, Dawn M; Mores, Christopher N

2015-01-01

Mosquito-borne diseases cause significant public health burden and are widely re-emerging or emerging. Understanding, predicting, and mitigating the spread of mosquito-borne disease in diverse populations and geographies are ongoing modelling challenges. We propose a hybrid network-patch model for the spread of mosquito-borne pathogens that accounts for individual movement through mosquito habitats, extending the capabilities of existing agent-based models (ABMs) to include vector-borne diseases. The ABM are coupled with differential equations representing 'clouds' of mosquitoes in patches accounting for mosquito ecology. We adapted an ABM for humans using this method and investigated the importance of heterogeneity in pathogen spread, motivating the utility of models of individual behaviour. We observed that the final epidemic size is greater in patch models with a high risk patch frequently visited than in a homogeneous model. Our hybrid model quantifies the importance of the heterogeneity in the spread of mosquito-borne pathogens, guiding mitigation strategies.

Air travel and vector-borne disease movement.

PubMed

Tatem, A J; Huang, Z; Das, A; Qi, Q; Roth, J; Qiu, Y

2012-12-01

Recent decades have seen substantial expansions in the global air travel network and rapid increases in traffic volumes. The effects of this are well studied in terms of the spread of directly transmitted infections, but the role of air travel in the movement of vector-borne diseases is less well understood. Increasingly however, wider reaching surveillance for vector-borne diseases and our improving abilities to map the distributions of vectors and the diseases they carry, are providing opportunities to better our understanding of the impact of increasing air travel. Here we examine global trends in the continued expansion of air transport and its impact upon epidemiology. Novel malaria and chikungunya examples are presented, detailing how geospatial data in combination with information on air traffic can be used to predict the risks of vector-borne disease importation and establishment. Finally, we describe the development of an online tool, the Vector-Borne Disease Airline Importation Risk (VBD-Air) tool, which brings together spatial data on air traffic and vector-borne disease distributions to quantify the seasonally changing risks for importation to non-endemic regions. Such a framework provides the first steps towards an ultimate goal of adaptive management based on near real time flight data and vector-borne disease surveillance.

Vector-Borne Pathogen and Host Evolution in a Structured Immuno-Epidemiological System.

PubMed

Gulbudak, Hayriye; Cannataro, Vincent L; Tuncer, Necibe; Martcheva, Maia

2017-02-01

Vector-borne disease transmission is a common dissemination mode used by many pathogens to spread in a host population. Similar to directly transmitted diseases, the within-host interaction of a vector-borne pathogen and a host's immune system influences the pathogen's transmission potential between hosts via vectors. Yet there are few theoretical studies on virulence-transmission trade-offs and evolution in vector-borne pathogen-host systems. Here, we consider an immuno-epidemiological model that links the within-host dynamics to between-host circulation of a vector-borne disease. On the immunological scale, the model mimics antibody-pathogen dynamics for arbovirus diseases, such as Rift Valley fever and West Nile virus. The within-host dynamics govern transmission and host mortality and recovery in an age-since-infection structured host-vector-borne pathogen epidemic model. By considering multiple pathogen strains and multiple competing host populations differing in their within-host replication rate and immune response parameters, respectively, we derive evolutionary optimization principles for both pathogen and host. Invasion analysis shows that the [Formula: see text] maximization principle holds for the vector-borne pathogen. For the host, we prove that evolution favors minimizing case fatality ratio (CFR). These results are utilized to compute host and pathogen evolutionary trajectories and to determine how model parameters affect evolution outcomes. We find that increasing the vector inoculum size increases the pathogen [Formula: see text], but can either increase or decrease the pathogen virulence (the host CFR), suggesting that vector inoculum size can contribute to virulence of vector-borne diseases in distinct ways.

Knowledge, Attitude and Practices of Vector-Borne Disease Prevention during the Emergence of a New Arbovirus: Implications for the Control of Chikungunya Virus in French Guiana.

PubMed

Fritzell, Camille; Raude, Jocelyn; Adde, Antoine; Dusfour, Isabelle; Quenel, Philippe; Flamand, Claude

2016-11-01

During the last decade, French Guiana has been affected by major dengue fever outbreaks. Although this arbovirus has been a focus of many awareness campaigns, very little information is available about beliefs, attitudes and behaviors regarding vector-borne diseases among the population of French Guiana. During the first outbreak of the chikungunya virus, a quantitative survey was conducted among high school students to study experiences, practices and perceptions related to mosquito-borne diseases and to identify socio-demographic, cognitive and environmental factors that could be associated with the engagement in protective behaviors. A cross-sectional survey was administered in May 2014, with a total of 1462 students interviewed. Classrooms were randomly selected using a two-stage selection procedure with cluster samples. A multiple correspondence analysis (MCA) associated with a hierarchical cluster analysis and with an ordinal logistic regression was performed. Chikungunya was less understood and perceived as a more dreadful disease than dengue fever. The analysis identified three groups of individual protection levels against mosquito-borne diseases: "low" (30%), "moderate" (42%) and "high" (28%)". Protective health behaviors were found to be performed more frequently among students who were female, had a parent with a higher educational status, lived in an individual house, and had a better understanding of the disease. This study allowed us to estimate the level of protective practices against vector-borne diseases among students after the emergence of a new arbovirus. These results revealed that the adoption of protective behaviors is a multi-factorial process that depends on both sociocultural and cognitive factors. These findings may help public health authorities to strengthen communication and outreach strategies, thereby increasing the adoption of protective health behaviors, particularly in high-risk populations.

Effects of Climate and Climate Change on Vectors and Vector-Borne Diseases: Ticks Are Different.

PubMed

Ogden, Nick H; Lindsay, L Robbin

2016-08-01

There has been considerable debate as to whether global risk from vector-borne diseases will be impacted by climate change. This has focussed on important mosquito-borne diseases that are transmitted by the vectors from infected to uninfected humans. However, this debate has mostly ignored the biological diversity of vectors and vector-borne diseases. Here, we review how climate and climate change may impact those most divergent of arthropod disease vector groups: multivoltine insects and hard-bodied (ixodid) ticks. We contrast features of the life cycles and behaviour of these arthropods, and how weather, climate, and climate change may have very different impacts on the spatiotemporal occurrence and abundance of vectors, and the pathogens they transmit. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Web-based GIS: the vector-borne disease airline importation risk (VBD-AIR) tool

PubMed Central

2012-01-01

Background Over the past century, the size and complexity of the air travel network has increased dramatically. Nowadays, there are 29.6 million scheduled flights per year and around 2.7 billion passengers are transported annually. The rapid expansion of the network increasingly connects regions of endemic vector-borne disease with the rest of the world, resulting in challenges to health systems worldwide in terms of vector-borne pathogen importation and disease vector invasion events. Here we describe the development of a user-friendly Web-based GIS tool: the Vector-Borne Disease Airline Importation Risk Tool (VBD-AIR), to help better define the roles of airports and airlines in the transmission and spread of vector-borne diseases. Methods Spatial datasets on modeled global disease and vector distributions, as well as climatic and air network traffic data were assembled. These were combined to derive relative risk metrics via air travel for imported infections, imported vectors and onward transmission, and incorporated into a three-tier server architecture in a Model-View-Controller framework with distributed GIS components. A user-friendly web-portal was built that enables dynamic querying of the spatial databases to provide relevant information. Results The VBD-AIR tool constructed enables the user to explore the interrelationships among modeled global distributions of vector-borne infectious diseases (malaria. dengue, yellow fever and chikungunya) and international air service routes to quantify seasonally changing risks of vector and vector-borne disease importation and spread by air travel, forming an evidence base to help plan mitigation strategies. The VBD-AIR tool is available at http://www.vbd-air.com. Conclusions VBD-AIR supports a data flow that generates analytical results from disparate but complementary datasets into an organized cartographical presentation on a web map for the assessment of vector-borne disease movements on the air travel network. The framework built provides a flexible and robust informatics infrastructure by separating the modules of functionality through an ontological model for vector-borne disease. The VBD‒AIR tool is designed as an evidence base for visualizing the risks of vector-borne disease by air travel for a wide range of users, including planners and decisions makers based in state and local government, and in particular, those at international and domestic airports tasked with planning for health risks and allocating limited resources. PMID:22892045

Web-based GIS: the vector-borne disease airline importation risk (VBD-AIR) tool.

PubMed

Huang, Zhuojie; Das, Anirrudha; Qiu, Youliang; Tatem, Andrew J

2012-08-14

Over the past century, the size and complexity of the air travel network has increased dramatically. Nowadays, there are 29.6 million scheduled flights per year and around 2.7 billion passengers are transported annually. The rapid expansion of the network increasingly connects regions of endemic vector-borne disease with the rest of the world, resulting in challenges to health systems worldwide in terms of vector-borne pathogen importation and disease vector invasion events. Here we describe the development of a user-friendly Web-based GIS tool: the Vector-Borne Disease Airline Importation Risk Tool (VBD-AIR), to help better define the roles of airports and airlines in the transmission and spread of vector-borne diseases. Spatial datasets on modeled global disease and vector distributions, as well as climatic and air network traffic data were assembled. These were combined to derive relative risk metrics via air travel for imported infections, imported vectors and onward transmission, and incorporated into a three-tier server architecture in a Model-View-Controller framework with distributed GIS components. A user-friendly web-portal was built that enables dynamic querying of the spatial databases to provide relevant information. The VBD-AIR tool constructed enables the user to explore the interrelationships among modeled global distributions of vector-borne infectious diseases (malaria. dengue, yellow fever and chikungunya) and international air service routes to quantify seasonally changing risks of vector and vector-borne disease importation and spread by air travel, forming an evidence base to help plan mitigation strategies. The VBD-AIR tool is available at http://www.vbd-air.com. VBD-AIR supports a data flow that generates analytical results from disparate but complementary datasets into an organized cartographical presentation on a web map for the assessment of vector-borne disease movements on the air travel network. The framework built provides a flexible and robust informatics infrastructure by separating the modules of functionality through an ontological model for vector-borne disease. The VBD‒AIR tool is designed as an evidence base for visualizing the risks of vector-borne disease by air travel for a wide range of users, including planners and decisions makers based in state and local government, and in particular, those at international and domestic airports tasked with planning for health risks and allocating limited resources.

Emerging Vector-Borne Diseases – Incidence through Vectors

PubMed Central

Savić, Sara; Vidić, Branka; Grgić, Zivoslav; Potkonjak, Aleksandar; Spasojevic, Ljubica

2014-01-01

Vector-borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowadays, in intercontinental countries, there is a struggle with emerging diseases, which have found their way to appear through vectors. Vector-borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens, and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector-borne infectious diseases and disease outbreaks. It could affect the range and population of pathogens, host and vectors, transmission season, etc. Reliable surveillance for diseases that are most likely to emerge is required. Canine vector-borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, ehrlichiosis, and leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fundamental role at primarily prevention and then treatment of vector-borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases. During a 4-year period, from 2009 to 2013, a total number of 551 dog samples were analyzed for vector-borne diseases (borreliosis, babesiosis, ehrlichiosis, anaplasmosis, dirofilariosis, and leishmaniasis) in routine laboratory work. The analysis was done by serological tests – ELISA for borreliosis, dirofilariosis, and leishmaniasis, modified Knott test for dirofilariosis, and blood smear for babesiosis, ehrlichiosis, and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on average more then half of the samples brought to the laboratory to analysis for different infectious diseases are analyzed for vector-borne diseases. In the region of Vojvodina (northern part of Serbia), the following vector-borne infectious diseases have been found in dogs so far borreliosis, babesiosis, dirofilariosis, leishmaniasis, and anaplasmosis. PMID:25520951

Emerging Vector-Borne Diseases - Incidence through Vectors.

PubMed

Savić, Sara; Vidić, Branka; Grgić, Zivoslav; Potkonjak, Aleksandar; Spasojevic, Ljubica

2014-01-01

Vector-borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowadays, in intercontinental countries, there is a struggle with emerging diseases, which have found their way to appear through vectors. Vector-borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens, and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector-borne infectious diseases and disease outbreaks. It could affect the range and population of pathogens, host and vectors, transmission season, etc. Reliable surveillance for diseases that are most likely to emerge is required. Canine vector-borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, ehrlichiosis, and leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fundamental role at primarily prevention and then treatment of vector-borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases. During a 4-year period, from 2009 to 2013, a total number of 551 dog samples were analyzed for vector-borne diseases (borreliosis, babesiosis, ehrlichiosis, anaplasmosis, dirofilariosis, and leishmaniasis) in routine laboratory work. The analysis was done by serological tests - ELISA for borreliosis, dirofilariosis, and leishmaniasis, modified Knott test for dirofilariosis, and blood smear for babesiosis, ehrlichiosis, and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on average more then half of the samples brought to the laboratory to analysis for different infectious diseases are analyzed for vector-borne diseases. In the region of Vojvodina (northern part of Serbia), the following vector-borne infectious diseases have been found in dogs so far borreliosis, babesiosis, dirofilariosis, leishmaniasis, and anaplasmosis.

Vector-borne diseases in Haiti: a review.

PubMed

Ben-Chetrit, Eli; Schwartz, Eli

2015-01-01

Haiti lies on the western third of the island of Hispaniola in the Caribbean, and is one of the poorest nations in the Western hemisphere. Haiti attracts a lot of medical attention and support due to severe natural disasters followed by disastrous health consequences. Vector-borne infections are still prevalent there with some unique aspects comparing it to Latin American countries and other Caribbean islands. Although vector-borne viral diseases such as dengue and recently chikungunya can be found in many of the Caribbean islands, including Haiti, there is an apparent distinction of the vector-borne parasitic diseases. Contrary to neighboring Carribbean islands, Haiti is highly endemic for malaria, lymphatic filariasis and mansonellosis. Affected by repeat natural disasters, poverty and lack of adequate infrastructure, control of transmission within Haiti and prevention of dissemination of vector-borne pathogens to other regions is challenging. In this review we summarize some aspects concerning diseases caused by vector-borne pathogens in Haiti. Copyright © 2015 Elsevier Ltd. All rights reserved.

Changes in Black-legged Tick Population in New England with Future Climate Change

NASA Astrophysics Data System (ADS)

Krishnan, S.; Huber, M.

2015-12-01

Lyme disease is one of the most frequently reported vector-borne diseases in the United States. In the Northeastern United States, vector transmission is maintained in a horizontal transmission cycle between the vector, the black-legged ticks, and the vertebrate reservoir hosts, which include white-tailed deer, rodents and other medium to large sized mammals. Predicting how vector populations change with future climate change is critical to understanding disease spread in the future, and for developing suitable regional adaptation strategies. For the United States, these predictions have mostly been made using regressions based on field and lab studies, or using spatial suitability studies. However, the relation between tick populations at various life-cycle stages and climate variables are complex, necessitating a mechanistic approach. In this study, we present a framework for driving a mechanistic tick population model with high-resolution regional climate modeling projections. The goal is to estimate changes in black-legged tick populations in New England for the 21st century. The tick population model used is based on the mechanistic approach of Ogden et al., (2005) developed for Canada. Dynamically downscaled climate projections at a 3-kms resolution using the Weather and Research Forecasting Model (WRF) are used to drive the tick population model.

Spatial disaggregation of tick occurrence and ecology at a local scale as a preliminary step for spatial surveillance of tick-borne diseases: general framework and health implications in Belgium

PubMed Central

2013-01-01

Background The incidence of tick-borne diseases is increasing in Europe. Sub national information on tick distribution, ecology and vector status is often lacking. However, precise location of infection risk can lead to better targeted prevention measures, surveillance and control. Methods In this context, the current paper compiled geolocated tick occurrences in Belgium, a country where tick-borne disease has received little attention, in order to highlight the potential value of spatial approaches and draw some recommendations for future research priorities. Results Mapping of 89,289 ticks over 654 sites revealed that ticks such as Ixodes ricinus and Ixodes hexagonus are largely present while Dermacentor reticulatus has a patchy distribution. Suspected hot spots of tick diversity might favor pathogen exchanges and suspected hot spots of I. ricinus abundance might increase human-vector contact locally. This underlines the necessity to map pathogens and ticks in detail. While I. ricinus is the main vector, I. hexagonus is a vector and reservoir of Borrelia burgdorferi s.l., which is active the whole year and is also found in urban settings. This and other nidiculous species bite humans less frequently, but seem to harbour pathogens. Their role in maintaining a pathogenic cycle within the wildlife merits investigation as they might facilitate transmission to humans if co-occurring with I. ricinus. Many micro-organisms are found abroad in tick species present in Belgium. Most have not been recorded locally but have not been searched for. Some are transmitted directly at the time of the bite, suggesting promotion of tick avoidance additionally to tick removal. Conclusion This countrywide approach to tick-borne diseases has helped delineate recommendations for future research priorities necessary to design public health policies aimed at spatially integrating the major components of the ecological cycle of tick-borne diseases. A systematic survey of tick species and associated pathogens is called for in Europe, as well as better characterisation of species interaction in the ecology of tick-borne diseases, those being all tick species, pathogens, hosts and other species which might play a role in tick-borne diseases complex ecosystems. PMID:23800283

Ecology and Epidemiology of Lyme Borreliosis.

PubMed

Schotthoefer, Anna M; Frost, Holly M

2015-12-01

Lyme borreliosis is a zoonotic, tick-borne disease that infects humans worldwide. The disease is currently recognized as the most common vector-borne disease in Europe and North America. Disease is caused by several genospecies of the Borrelia burgdorferi sensu lato complex. Humans are at high risk of infection in regions where highly competent reservoirs are the primary hosts for the subadult stages of the tick, in contrast to regions where less competent or refractory animals feed ticks. Human infections are also most frequently associated with spring and summer months when the nymph stage of the tick is active. Copyright © 2015 Elsevier Inc. All rights reserved.

Quantifying the roles of host movement and vector dispersal in the transmission of vector-borne diseases of livestock.

PubMed

Sumner, Tom; Orton, Richard J; Green, Darren M; Kao, Rowland R; Gubbins, Simon

2017-04-01

The role of host movement in the spread of vector-borne diseases of livestock has been little studied. Here we develop a mathematical framework that allows us to disentangle and quantify the roles of vector dispersal and livestock movement in transmission between farms. We apply this framework to outbreaks of bluetongue virus (BTV) and Schmallenberg virus (SBV) in Great Britain, both of which are spread by Culicoides biting midges and have recently emerged in northern Europe. For BTV we estimate parameters by fitting the model to outbreak data using approximate Bayesian computation, while for SBV we use previously derived estimates. We find that around 90% of transmission of BTV between farms is a result of vector dispersal, while for SBV this proportion is 98%. This difference is a consequence of higher vector competence and shorter duration of viraemia for SBV compared with BTV. For both viruses we estimate that the mean number of secondary infections per infected farm is greater than one for vector dispersal, but below one for livestock movements. Although livestock movements account for a small proportion of transmission and cannot sustain an outbreak on their own, they play an important role in establishing new foci of infection. However, the impact of restricting livestock movements on the spread of both viruses depends critically on assumptions made about the distances over which vector dispersal occurs. If vector dispersal occurs primarily at a local scale (99% of transmission occurs <25 km), movement restrictions are predicted to be effective at reducing spread, but if dispersal occurs frequently over longer distances (99% of transmission occurs <50 km) they are not.

Quantifying the roles of host movement and vector dispersal in the transmission of vector-borne diseases of livestock

PubMed Central

Sumner, Tom; Orton, Richard J.; Green, Darren M.; Kao, Rowland R.

2017-01-01

The role of host movement in the spread of vector-borne diseases of livestock has been little studied. Here we develop a mathematical framework that allows us to disentangle and quantify the roles of vector dispersal and livestock movement in transmission between farms. We apply this framework to outbreaks of bluetongue virus (BTV) and Schmallenberg virus (SBV) in Great Britain, both of which are spread by Culicoides biting midges and have recently emerged in northern Europe. For BTV we estimate parameters by fitting the model to outbreak data using approximate Bayesian computation, while for SBV we use previously derived estimates. We find that around 90% of transmission of BTV between farms is a result of vector dispersal, while for SBV this proportion is 98%. This difference is a consequence of higher vector competence and shorter duration of viraemia for SBV compared with BTV. For both viruses we estimate that the mean number of secondary infections per infected farm is greater than one for vector dispersal, but below one for livestock movements. Although livestock movements account for a small proportion of transmission and cannot sustain an outbreak on their own, they play an important role in establishing new foci of infection. However, the impact of restricting livestock movements on the spread of both viruses depends critically on assumptions made about the distances over which vector dispersal occurs. If vector dispersal occurs primarily at a local scale (99% of transmission occurs <25 km), movement restrictions are predicted to be effective at reducing spread, but if dispersal occurs frequently over longer distances (99% of transmission occurs <50 km) they are not. PMID:28369082

Tick-Borne Zoonoses in the United States: Persistent and Emerging Threats to Human Health

PubMed Central

Eisen, Rebecca J.; Kugeler, Kiersten J.; Eisen, Lars; Beard, Charles B.; Paddock, Christopher D.

2017-01-01

In the United States, ticks transmit the greatest diversity of arthropod-borne pathogens and are responsible for the most cases of all vector-borne diseases. In recent decades, the number of reported cases of notifiable tick-borne diseases has steadily increased, geographic distributions of many ticks and tick-borne diseases have expanded, and new tick-borne disease agents have been recognized. In this review, we (1) describe the known disease agents associated with the most commonly human-biting ixodid ticks, (2) review the natural histories of these ticks and their associated pathogens, (3) highlight spatial and temporal changes in vector tick distributions and tick-borne disease occurrence in recent decades, and (4) identify knowledge gaps and barriers to more effective prevention of tick-borne diseases. We describe 12 major tick-borne diseases caused by 15 distinct disease agents that are transmitted by the 8 most commonly human-biting ixodid ticks in the United States. Notably, 40% of these pathogens were described within the last two decades. Our assessment highlights the importance of animal studies to elucidate how tick-borne pathogens are maintained in nature, as well as advances in molecular detection of pathogens which has led to the discovery of several new tick-borne disease agents. PMID:28369515

Climate change and vector-borne diseases of public health significance.

PubMed

Ogden, Nicholas H

2017-10-16

There has been much debate as to whether or not climate change will have, or has had, any significant effect on risk from vector-borne diseases. The debate on the former has focused on the degree to which occurrence and levels of risk of vector-borne diseases are determined by climate-dependent or independent factors, while the debate on the latter has focused on whether changes in disease incidence are due to climate at all, and/or are attributable to recent climate change. Here I review possible effects of climate change on vector-borne diseases, methods used to predict these effects and the evidence to date of changes in vector-borne disease risks that can be attributed to recent climate change. Predictions have both over- and underestimated the effects of climate change. Mostly under-estimations of effects are due to a focus only on direct effects of climate on disease ecology while more distal effects on society's capacity to control and prevent vector-borne disease are ignored. There is increasing evidence for possible impacts of recent climate change on some vector-borne diseases but for the most part, observed data series are too short (or non-existent), and impacts of climate-independent factors too great, to confidently attribute changing risk to climate change. © Crown copyright 2017.

Major emerging vector-borne zoonotic diseases of public health importance in Canada

PubMed Central

Kulkarni, Manisha A; Berrang-Ford, Lea; Buck, Peter A; Drebot, Michael A; Lindsay, L Robbin; Ogden, Nicholas H

2015-01-01

In Canada, the emergence of vector-borne diseases may occur via international movement and subsequent establishment of vectors and pathogens, or via northward spread from endemic areas in the USA. Re-emergence of endemic vector-borne diseases may occur due to climate-driven changes to their geographic range and ecology. Lyme disease, West Nile virus (WNV), and other vector-borne diseases were identified as priority emerging non-enteric zoonoses in Canada in a prioritization exercise conducted by public health stakeholders in 2013. We review and present the state of knowledge on the public health importance of these high priority emerging vector-borne diseases in Canada. Lyme disease is emerging in Canada due to range expansion of the tick vector, which also signals concern for the emergence of human granulocytic anaplasmosis, babesiosis, and Powassan virus. WNV has been established in Canada since 2001, with epidemics of varying intensity in following years linked to climatic drivers. Eastern equine encephalitis virus, Jamestown Canyon virus, snowshoe hare virus, and Cache Valley virus are other mosquito-borne viruses endemic to Canada with the potential for human health impact. Increased surveillance for emerging pathogens and vectors and coordinated efforts among sectors and jurisdictions will aid in early detection and timely public health response. PMID:26954882

Major emerging vector-borne zoonotic diseases of public health importance in Canada.

PubMed

Kulkarni, Manisha A; Berrang-Ford, Lea; Buck, Peter A; Drebot, Michael A; Lindsay, L Robbin; Ogden, Nicholas H

2015-06-10

In Canada, the emergence of vector-borne diseases may occur via international movement and subsequent establishment of vectors and pathogens, or via northward spread from endemic areas in the USA. Re-emergence of endemic vector-borne diseases may occur due to climate-driven changes to their geographic range and ecology. Lyme disease, West Nile virus (WNV), and other vector-borne diseases were identified as priority emerging non-enteric zoonoses in Canada in a prioritization exercise conducted by public health stakeholders in 2013. We review and present the state of knowledge on the public health importance of these high priority emerging vector-borne diseases in Canada. Lyme disease is emerging in Canada due to range expansion of the tick vector, which also signals concern for the emergence of human granulocytic anaplasmosis, babesiosis, and Powassan virus. WNV has been established in Canada since 2001, with epidemics of varying intensity in following years linked to climatic drivers. Eastern equine encephalitis virus, Jamestown Canyon virus, snowshoe hare virus, and Cache Valley virus are other mosquito-borne viruses endemic to Canada with the potential for human health impact. Increased surveillance for emerging pathogens and vectors and coordinated efforts among sectors and jurisdictions will aid in early detection and timely public health response.

Surveillance of Arthropod Vector-Borne Infectious Diseases Using Remote Sensing Techniques: A Review

PubMed Central

Kalluri, Satya; Gilruth, Peter; Rogers, David; Szczur, Martha

2007-01-01

Epidemiologists are adopting new remote sensing techniques to study a variety of vector-borne diseases. Associations between satellite-derived environmental variables such as temperature, humidity, and land cover type and vector density are used to identify and characterize vector habitats. The convergence of factors such as the availability of multi-temporal satellite data and georeferenced epidemiological data, collaboration between remote sensing scientists and biologists, and the availability of sophisticated, statistical geographic information system and image processing algorithms in a desktop environment creates a fertile research environment. The use of remote sensing techniques to map vector-borne diseases has evolved significantly over the past 25 years. In this paper, we review the status of remote sensing studies of arthropod vector-borne diseases due to mosquitoes, ticks, blackflies, tsetse flies, and sandflies, which are responsible for the majority of vector-borne diseases in the world. Examples of simple image classification techniques that associate land use and land cover types with vector habitats, as well as complex statistical models that link satellite-derived multi-temporal meteorological observations with vector biology and abundance, are discussed here. Future improvements in remote sensing applications in epidemiology are also discussed. PMID:17967056

Effect of climate change on vector-borne disease risk in the UK.

PubMed

Medlock, Jolyon M; Leach, Steve A

2015-06-01

During the early part of the 21st century, an unprecedented change in the status of vector-borne disease in Europe has occurred. Invasive mosquitoes have become widely established across Europe, with subsequent transmission and outbreaks of dengue and chikungunya virus. Malaria has re-emerged in Greece, and West Nile virus has emerged throughout parts of eastern Europe. Tick-borne diseases, such as Lyme disease, continue to increase, or, in the case of tick-borne encephalitis and Crimean-Congo haemorrhagic fever viruses, have changed their geographical distribution. From a veterinary perspective, the emergence of Bluetongue and Schmallenberg viruses show that northern Europe is equally susceptible to transmission of vector-borne disease. These changes are in part due to increased globalisation, with intercontinental air travel and global shipping transport creating new opportunities for invasive vectors and pathogens. However, changes in vector distributions are being driven by climatic changes and changes in land use, infrastructure, and the environment. In this Review, we summarise the risks posed by vector-borne diseases in the present and the future from a UK perspective, and assess the likely effects of climate change and, where appropriate, climate-change adaptation strategies on vector-borne disease risk in the UK. Lessons from the outbreaks of West Nile virus in North America and chikungunya in the Caribbean emphasise the need to assess future vector-borne disease risks and prepare contingencies for future outbreaks. Ensuring that adaptation strategies for climate change do not inadvertently exacerbate risks should be a primary focus for decision makers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Implementing a vector surveillance-response system for chagas disease control: a 4-year field trial in Nicaragua.

PubMed

Yoshioka, Kota; Tercero, Doribel; Pérez, Byron; Nakamura, Jiro; Pérez, Lenin

2017-03-06

Chagas disease is one of the neglected tropical diseases (NTDs). International goals for its control involve elimination of vector-borne transmission. Central American countries face challenges in establishing sustainable vector control programmes, since the main vector, Triatoma dimidiata, cannot be eliminated. In 2012, the Ministry of Health in Nicaragua started a field test of a vector surveillance-response system to control domestic vector infestation. This paper reports the main findings from this pilot study. This study was carried out from 2012 to 2015 in the Municipality of Totogalpa. The Japan International Cooperation Agency provided technical cooperation in designing and monitoring the surveillance-response system until 2014. This system involved 1) vector reports by householders to health facilities, 2) data analysis and planning of responses at the municipal health centre and 3) house visits or insecticide spraying by health personnel as a response. We registered all vector reports and responses in a digital database. The collected data were used to describe and analyse the system performance in terms of amount of vector reports as well as rates and timeliness of responses. During the study period, T. dimidiata was reported 396 times. Spatiotemporal analysis identified some high-risk clusters. All houses reported to be infested were visited by health personnel in 2013 and this response rate dropped to 39% in 2015. Rates of insecticide spraying rose above 80% in 2013 but no spraying was carried out in the following 2 years. The timeliness of house visits improved significantly after the responsibility was transferred from a vector control technician to primary health care staff. We argue that the proposed vector surveillance-response system is workable within the resource-constrained health system in Nicaragua. Integration to the primary health care services was a key to improve the system performance. Continual efforts are necessary to keep adapting the surveillance-response system to the dynamic health systems. We also discuss that the goal of eliminating vector-borne transmission remains unachievable. This paper provides lessons not only for Chagas disease control in Central America, but also for control efforts for other NTDs that need a sustainable surveillance-response system to support elimination.

Arboviral diseases and malaria in Australia, 2013-14: Annual report of the National Arbovirus and Malaria Advisory Committee.

PubMed

Knope, Katrina E; Muller, Mike; Kurucz, Nina; Doggett, Stephen L; Feldman, Rebecca; Johansen, Cheryl A; Hobby, Michaela; Bennett, Sonya; Lynch, Stacey; Sly, Angus; Currie, Bart J

2016-09-30

This report describes the epidemiology of mosquito-borne diseases of public health importance in Australia during the 2013-14 season (1 July 2013 to 30 June 2014) and includes data from human notifications, sentinel chicken, vector and virus surveillance programs. The National Notifiable Diseases Surveillance System received notifications for 8,898 cases of disease transmitted by mosquitoes during the 2013-14 season. The Australasian alphaviruses Barmah Forest virus and Ross River virus accounted for 6,372 (72%) total notifications. However, over-diagnosis and possible false positive diagnostic test results for these 2 infections mean that the true burden of infection is likely overestimated, and as a consequence, the case definitions have been amended. There were 94 notifications of imported chikungunya virus infection and 13 cases of imported Zika virus infection. There were 212 notifications of dengue virus infection acquired in Australia and 1,795 cases acquired overseas, with an additional 14 cases for which the place of acquisition was unknown. Imported cases of dengue were most frequently acquired in Indonesia (51%). No cases of locally-acquired malaria were notified during the 2013-14 season, though there were 373 notifications of overseas-acquired malaria. In 2013-14, arbovirus and mosquito surveillance programs were conducted in most jurisdictions. Surveillance for exotic mosquitoes at international ports of entry continues to be a vital part of preventing the spread of vectors of mosquito-borne diseases such as dengue to new areas of Australia, with 13 detections of exotic mosquitoes at the ports of entry in 2013-14.

Optimization of Control Strategies for Non-Domiciliated Triatoma dimidiata, Chagas Disease Vector in the Yucatán Peninsula, Mexico

PubMed Central

Barbu, Corentin; Dumonteil, Eric; Gourbière, Sébastien

2009-01-01

Background Chagas disease is the most important vector-borne disease in Latin America. Regional initiatives based on residual insecticide spraying have successfully controlled domiciliated vectors in many regions. Non-domiciliated vectors remain responsible for a significant transmission risk, and their control is now a key challenge for disease control. Methodology/Principal Findings A mathematical model was developed to predict the temporal variations in abundance of non-domiciliated vectors inside houses. Demographic parameters were estimated by fitting the model to two years of field data from the Yucatan peninsula, Mexico. The predictive value of the model was tested on an independent data set before simulations examined the efficacy of control strategies based on residual insecticide spraying, insect screens, and bednets. The model accurately fitted and predicted field data in the absence and presence of insecticide spraying. Pyrethroid spraying was found effective when 50 mg/m2 were applied yearly within a two-month period matching the immigration season. The >80% reduction in bug abundance was not improved by larger doses or more frequent interventions, and it decreased drastically for different timing and lower frequencies of intervention. Alternatively, the use of insect screens consistently reduced bug abundance proportionally to the reduction of the vector immigration rate. Conclusion/Significance Control of non-domiciliated vectors can hardly be achieved by insecticide spraying, because it would require yearly application and an accurate understanding of the temporal pattern of immigration. Insect screens appear to offer an effective and sustainable alternative, which may be part of multi-disease interventions for the integrated control of neglected vector-borne diseases. PMID:19365542

Host Life History Strategy, Species Diversity, and Habitat Influence Trypanosoma cruzi Vector Infection in Changing Landscapes

PubMed Central

Gottdenker, Nicole L.; Chaves, Luis Fernando; Calzada, José E.; Saldaña, Azael; Carroll, C. Ronald

2012-01-01

Background Anthropogenic land use may influence transmission of multi-host vector-borne pathogens by changing diversity, relative abundance, and community composition of reservoir hosts. These reservoir hosts may have varying competence for vector-borne pathogens depending on species-specific characteristics, such as life history strategy. The objective of this study is to evaluate how anthropogenic land use change influences blood meal species composition and the effects of changing blood meal species composition on the parasite infection rate of the Chagas disease vector Rhodnius pallescens in Panama. Methodology/Principal Findings R. pallescens vectors (N = 643) were collected in different habitat types across a gradient of anthropogenic disturbance. Blood meal species in DNA extracted from these vectors was identified in 243 (40.3%) vectors by amplification and sequencing of a vertebrate-specific fragment of the 12SrRNA gene, and T. cruzi vector infection was determined by pcr. Vector infection rate was significantly greater in deforested habitats as compared to contiguous forests. Forty-two different species of blood meal were identified in R. pallescens, and species composition of blood meals varied across habitat types. Mammals (88.3%) dominated R. pallescens blood meals. Xenarthrans (sloths and tamanduas) were the most frequently identified species in blood meals across all habitat types. A regression tree analysis indicated that blood meal species diversity, host life history strategy (measured as rmax, the maximum intrinsic rate of population increase), and habitat type (forest fragments and peridomiciliary sites) were important determinants of vector infection with T. cruzi. The mean intrinsic rate of increase and the skewness and variability of rmax were positively associated with higher vector infection rate at a site. Conclusions/Significance In this study, anthropogenic landscape disturbance increased vector infection with T. cruzi, potentially by changing host community structure to favor hosts that are short-lived with high reproductive rates. Study results apply to potential environmental management strategies for Chagas disease. PMID:23166846

International network for capacity building for the control of emerging viral vector-borne zoonotic diseases: ARBO-ZOONET.

PubMed

Ahmed, J; Bouloy, M; Ergonul, O; Fooks, Ar; Paweska, J; Chevalier, V; Drosten, C; Moormann, R; Tordo, N; Vatansever, Z; Calistri, P; Estrada-Pena, A; Mirazimi, A; Unger, H; Yin, H; Seitzer, U

2009-03-26

Arboviruses are arthropod-borne viruses, which include West Nile fever virus (WNFV), a mosquito-borne virus, Rift Valley fever virus (RVFV), a mosquito-borne virus, and Crimean-Congo haemorrhagic fever virus (CCHFV), a tick-borne virus. These arthropod-borne viruses can cause disease in different domestic and wild animals and in humans, posing a threat to public health because of their epidemic and zoonotic potential. In recent decades, the geographical distribution of these diseases has expanded. Outbreaks of WNF have already occurred in Europe, especially in the Mediterranean basin. Moreover, CCHF is endemic in many European countries and serious outbreaks have occurred, particularly in the Balkans, Turkey and Southern Federal Districts of Russia. In 2000, RVF was reported for the first time outside the African continent, with cases being confirmed in Saudi Arabia and Yemen. This spread was probably caused by ruminant trade and highlights that there is a threat of expansion of the virus into other parts of Asia and Europe. In the light of global warming and globalisation of trade and travel, public interest in emerging zoonotic diseases has increased. This is especially evident regarding the geographical spread of vector-borne diseases. A multi-disciplinary approach is now imperative, and groups need to collaborate in an integrated manner that includes vector control, vaccination programmes, improved therapy strategies, diagnostic tools and surveillance, public awareness, capacity building and improvement of infrastructure in endemic regions.

Interaction of Flavivirus with their mosquito vectors and their impact on the human health in the Americas.

PubMed

Valderrama, Anayansi; Díaz, Yamilka; López-Vergès, Sandra

2017-10-28

Some of the major arboviruses with public health importance, such as dengue, yellow fever, Zika and West Nile virus are mosquito-borne or mosquito-transmitted Flavivirus. Their principal vectors are from the family Culicidae, Aedes aegypti and Aedes albopictus being responsible of the urban cycles of dengue, Zika and yellow fever virus. These vectors are highly competent for transmission of many arboviruses. The genetic variability of the vectors, the environment and the viral diversity modulate the vector competence, in this context, it is important to determine which vector species is responsible of an outbreak in areas where many vectors coexist. As some vectors can transmit several flaviviruses and some flaviviruses can be transmitted by different species of vectors, through this review we expose importance of yellow fever, dengue and Zika virus in the world and the Americas, as well as the updated knowledge about these flaviviruses in their interaction with their mosquito vectors, guiding us on what is probably the beginning of a new stage in which the simultaneity of outbreaks will occur more frequently. Copyright © 2017 Elsevier Inc. All rights reserved.

What is the risk for exposure to vector-borne pathogens in United States national parks?

PubMed

Eisen, Lars; Wong, David; Shelus, Victoria; Eisen, Rebecca J

2013-03-01

United States national parks attract > 275 million visitors annually and collectively present risk of exposure for staff and visitors to a wide range of arthropod vector species (most notably fleas, mosquitoes, and ticks) and their associated bacterial, protozoan, or viral pathogens. We assessed the current state of knowledge for risk of exposure to vector-borne pathogens in national parks through a review of relevant literature, including internal National Park Service documents and organismal databases. We conclude that, because of lack of systematic surveillance for vector-borne pathogens in national parks, the risk of pathogen exposure for staff and visitors is unclear. Existing data for vectors within national parks were not based on systematic collections and rarely include evaluation for pathogen infection. Extrapolation of human-based surveillance data from neighboring communities likely provides inaccurate estimates for national parks because landscape differences impact transmission of vector-borne pathogens and human-vector contact rates likely differ inside versus outside the parks because of differences in activities or behaviors. Vector-based pathogen surveillance holds promise to define when and where within national parks the risk of exposure to infected vectors is elevated. A pilot effort, including 5-10 strategic national parks, would greatly improve our understanding of the scope and magnitude of vector-borne pathogen transmission in these high-use public settings. Such efforts also will support messaging to promote personal protection measures and inform park visitors and staff of their responsibility for personal protection, which the National Park Service preservation mission dictates as the core strategy to reduce exposure to vector-borne pathogens in national parks.

Vector control for malaria and other mosquito-borne diseases. Report of a WHO study group.

PubMed

1995-01-01

Since the Ministerial Conference on Malaria in 1992, which acknowledged the urgent need for worldwide commitment to malaria control, efforts have been directed to implementation of a Global Malaria Control Strategy. Vector control, an essential component of malaria control, has become less effective in recent years, partly as a result of poor use of alternative control tools, inappropriate use of insecticides, lack of an epidemiological basis for interventions, inadequate resources and infrastructure, and weak management. Changing environmental conditions, the behavioural characteristics of certain vectors, and resistance to insecticides have added to the difficulties. This report of a WHO Study Group provides guidelines for the planning, implementation and evaluation of cost-effective and sustainable vector control in the context of the Global Malaria Control Strategy. It reviews the available methods - indoor residual spraying, personal protection, larval control and environmental management - stressing the need for selective and flexible use of interventions according to local conditions. Requirements for data collection and the appropriate use of entomological parameters and techniques are discussed and priorities identified for the development of local capacity for vector control and for operational research. Emphasis is placed both on the monitoring and evaluation of vector control to ensure cost-effectiveness and on the development of strong managerial structures, which can support community participation and intersectoral collaboration and accommodate the control of other vector-borne diseases. The report concludes with recommendations aimed at promoting the targeted and efficient use of vector control in preventing and controlling malaria, thereby reducing the threat to health and socioeconomic development in many tropical countries.

Regulation of the Immune Response to α-Gal and Vector-borne Diseases.

PubMed

Cabezas-Cruz, Alejandro; Mateos-Hernández, Lourdes; Pérez-Cruz, Magdiel; Valdés, James J; Mera, Isabel G Fernández de; Villar, Margarita; de la Fuente, José

2015-10-01

Vector-borne diseases (VBD) challenge our understanding of emerging diseases. Recently, arthropod vectors have been involved in emerging anaphylactic diseases. In particular, the immunoglobulin E (IgE) antibody response to the carbohydrate Galα1-3Galβ1-(3)4GlcNAc-R (α-gal) following a tick bite was associated with allergies to red meat, cetuximab, and gelatin. By contrast, an anti-α-gal IgM antibody response was shown to protect against mosquito-borne malaria. Herein, we highlight the interplay between the gut microbiota, vectors, transmitted pathogens, and the regulation of the immune response as a model to understand the protective or allergic effect of α-gal. Establishing the source of α-gal in arthropod vectors and the immune response to vector bites and transmitted pathogens will be essential for diagnosing, treating, and ultimately preventing these emerging anaphylactic and other vector-borne diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Genetic resistance: tolerance to vector-borne diseases and the prospects and challenges of genomics.

PubMed

Bahbahani, H; Hanotte, O

2015-04-01

Vector-borne diseases in cattle and small ruminants (e.g. trypanosomosis, Rift Valley fever and East Coast fever) are associated with major economic losses in tropical countries, and particularly on the African continent. A variety of control strategies (e.g. management, vaccination and/or acaricide treatments) are used to minimise their negative impacts. These strategies are often associated with environmental, technical and/or economic drawbacks. However, several indigenous livestock populations have been reported to show a level of genetic tolerance or resistance to such disease challenges (e.g. trypanotolerant N'Dama cattle and Djallonké sheep). Use of these populations represents a sustainable alternative approach to minimising the negative impact of such infection/infestation on livestock production. This review summarises the current understanding of the genetic control of these adaptations, identifies knowledge gaps and critically examines the possible impacts of genomics approaches to the genetic improvement of tolerance and/or resistance to vector-borne diseases.

Countering Vector-Borne disease Threats. Presidential Address Given at the 82nd Annual Meeting of the American Mosquito Control Association, February 2016

USDA-ARS?s Scientific Manuscript database

The discovery of new, better and more ecologically friendly ways to prevent human and animal suffering from mosquito transmitted vector-borne diseases continues. Today the risk of vector-borne disease, specifically mosquito transmitted, threats increase dramatically as (1) climate extremes impact th...

Mosquitoes of Guam and the Northern Marianas: distribution, checklists, and notes on mosquito-borne pathogens.

PubMed

Rueda, Leopoldo M; Pecor, James E; Reeves, Will K; Wolf, Stephen P; Nunn, Peter V; Rabago, Rosanna Y; Gutierrez, Teresa L; Debboun, Mustapha

2011-01-01

This report includes the distribution records and updated checklists of the mosquitoes known to occur in Guam and nearby selected islands (ie, Saipan, Tinian, Rota), based on our field collections from various localities during 2010, published reports, and accessioned specimens deposited in the US National Museum of Natural History, Smithsonian Institution, Washington, DC. The status of common and potential mosquito vectors and their borne-pathogens are also noted.

New perspectives in tracing vector-borne interaction networks.

PubMed

Gómez-Díaz, Elena; Figuerola, Jordi

2010-10-01

Disentangling trophic interaction networks in vector-borne systems has important implications in epidemiological and evolutionary studies. Molecular methods based on bloodmeal typing in vectors have been increasingly used to identify hosts. Although most molecular approaches benefit from good specificity and sensitivity, their temporal resolution is limited by the often rapid digestion of blood, and mixed bloodmeals still remain a challenge for bloodmeal identification in multi-host vector systems. Stable isotope analyses represent a novel complementary tool that can overcome some of these problems. The utility of these methods using examples from different vector-borne systems are discussed and the extents to which they are complementary and versatile are highlighted. There are excellent opportunities for progress in the study of vector-borne transmission networks resulting from the integration of both molecular and stable isotope approaches. Copyright © 2010 Elsevier Ltd. All rights reserved.

Challenges in predicting climate and environmental effects on vector-borne disease episystems in a changing world.

PubMed

Tabachnick, W J

2010-03-15

Vector-borne pathogens cause enormous suffering to humans and animals. Many are expanding their range into new areas. Dengue, West Nile and Chikungunya have recently caused substantial human epidemics. Arthropod-borne animal diseases like Bluetongue, Rift Valley fever and African horse sickness pose substantial threats to livestock economies around the world. Climate change can impact the vector-borne disease epidemiology. Changes in climate will influence arthropod vectors, their life cycles and life histories, resulting in changes in both vector and pathogen distribution and changes in the ability of arthropods to transmit pathogens. Climate can affect the way pathogens interact with both the arthropod vector and the human or animal host. Predicting and mitigating the effects of future changes in the environment like climate change on the complex arthropod-pathogen-host epidemiological cycle requires understanding of a variety of complex mechanisms from the molecular to the population level. Although there has been substantial progress on many fronts the challenges to effectively understand and mitigate the impact of potential changes in the environment on vector-borne pathogens are formidable and at an early stage of development. The challenges will be explored using several arthropod-borne pathogen systems as illustration, and potential avenues to meet the challenges will be presented.

Surveillance of Zika virus infection in the EU/EEA, June 2015 to January 2017.

PubMed

Spiteri, G; Sudre, B; Septfons, A; Beauté, J

2017-10-01

Surveillance of Zika virus (ZIKV) infection in the European Union/European Economic Area (EU/EEA) was implemented in 2016 in response to the large outbreak reported in the Americas in 2015 associated with an increased number of infants born with microcephaly. Between June 2015 and January 2017, 21 EU/EEA countries reported 2,133 confirmed cases of ZIKV infection, of whom 106 were pregnant women. Cases infected in the Caribbean constituted 71% of reported cases. Almost all cases (99%) were most probably infected by mosquito bite during travel outside continental Europe, while only 1% were transmitted sexually. Considering that 584 imported cases were reported between May and October 2016 among residents of areas with established presence of Aedes albopictus , the absence of autochthonous vector-borne cases suggests that Ae. albopictus is not an efficient vector for ZIKV infection.

Vector-borne Infections

PubMed Central

Ben Beard, C.

2011-01-01

Infections with vector-borne pathogens are a major source of emerging diseases. The ability of vectors to bridge spatial and ecologic gaps between animals and humans increases opportunities for emergence. Small adaptations of a pathogen to a vector can have profound effects on the rate of transmission to humans. PMID:21529382

Distribution of tick-borne diseases in Japan: Past patterns and implications for the future.

PubMed

Yamaji, Kayoko; Aonuma, Hiroka; Kanuka, Hirotaka

2018-04-20

The rapid geographical spread of tick-borne diseases (TBDs) worldwide has recently provoked significant concerns amongst public health authorities. Tick-borne pathogens are maintained in enzootic cycles involving ticks and wild animal hosts, with epizootic spread to other mammals, including livestock and humans. Despite the increasing public health concern, current TBD diagnostic tests and treatments are inadequate, and predictive models of future risks posed by TBDs are limited by the heterogeneity of environmental, vector, and host factors, even in neighboring regions. In recent years, infections resulting in severe fever with thrombocytopenia syndrome (SFTS), Japanese spotted fever, and the scrub typhus pathogens have been reported frequently in addition to traditional TBDs in Japan. The Japanese archipelago is extremely elongated from north to south and its climate varies considerably, creating remarkable regional differences in tick species. The importance of continuous surveillance of TBDs has been growing in terms of geopathology - studies dealing with the relationships between geographic factors and the causes of specific diseases - in Japan and neighboring areas among eastern Asian countries, including China and Korea. In this review, we summarize detailed information regarding the history and epidemic status of human TBDs in Japan. Copyright © 2018 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Assessment of changes of vector borne diseases with wetland characteristics using multivariate analysis.

PubMed

Sheela, A M; Sarun, S; Justus, J; Vineetha, P; Sheeja, R V

2015-04-01

Vector borne diseases are a threat to human health. Little attention has been paid to the prevention of these diseases. We attempted to identify the significant wetland characteristics associated with the spread of chikungunya, dengue fever and malaria in Kerala, a tropical region of South West India using multivariate analyses (hierarchical cluster analysis, factor analysis and multiple regression). High/medium turbid coastal lagoons and inland water-logged wetlands with aquatic vegetation have significant effect on the incidence of chikungunya while dengue influenced by high turbid coastal beaches and malaria by medium turbid coastal beaches. The high turbidity in water is due to the urban waste discharge namely sewage, sullage and garbage from the densely populated cities and towns. The large extent of wetland is low land area favours the occurrence of vector borne diseases. Hence the provision of pollution control measures at source including soil erosion control measures is vital. The identification of vulnerable zones favouring the vector borne diseases will help the authorities to control pollution especially from urban areas and prevent these vector borne diseases. Future research should cover land use cover changes, climatic factors, seasonal variations in weather and pollution factors favouring the occurrence of vector borne diseases.

What is the Risk for Exposure to Vector-Borne Pathogens in United States National Parks?

PubMed Central

EISEN, LARS; WONG, DAVID; SHELUS, VICTORIA; EISEN, REBECCA J.

2015-01-01

United States national parks attract >275 million visitors annually and collectively present risk of exposure for staff and visitors to a wide range of arthropod vector species (most notably fleas, mosquitoes, and ticks) and their associated bacterial, protozoan, or viral pathogens. We assessed the current state of knowledge for risk of exposure to vector-borne pathogens in national parks through a review of relevant literature, including internal National Park Service documents and organismal databases. We conclude that, because of lack of systematic surveillance for vector-borne pathogens in national parks, the risk of pathogen exposure for staff and visitors is unclear. Existing data for vectors within national parks were not based on systematic collections and rarely include evaluation for pathogen infection. Extrapolation of human-based surveillance data from neighboring communities likely provides inaccurate estimates for national parks because landscape differences impact transmission of vector-borne pathogens and human-vector contact rates likely differ inside versus outside the parks because of differences in activities or behaviors. Vector-based pathogen surveillance holds promise to define when and where within national parks the risk of exposure to infected vectors is elevated. A pilot effort, including 5–10 strategic national parks, would greatly improve our understanding of the scope and magnitude of vector-borne pathogen transmission in these high-use public settings. Such efforts also will support messaging to promote personal protection measures and inform park visitors and staff of their responsibility for personal protection, which the National Park Service preservation mission dictates as the core strategy to reduce exposure to vector-borne pathogens in national parks. PMID:23540107

Molecular Detection of Bartonella Species in Blood-Feeding Bat Flies from Mexico.

PubMed

Moskaluk, Alexandra E; Stuckey, Matthew J; Jaffe, David A; Kasten, Rickie W; Aguilar-Setién, Alvaro; Olave-Leyva, José Ignacio; Galvez-Romero, Guillermo; Obregón-Morales, Cirani; Salas-Rojas, Mónica; García-Flores, María Martha; Aréchiga-Ceballos, Nidia; García-Baltazar, Anahí; Chomel, Bruno B

2018-05-01

Bartonellae are emerging blood-borne bacteria that have been recovered from a wide range of mammalian species and arthropod vectors around the world. Bats are now recognized as a potential wildlife reservoir for a diverse number of Bartonella species, including the zoonotic Candidatus B. mayotimonensis. These bat-borne Bartonella species have also been detected in the obligate ectoparasites of bats, such as blood-feeding flies, which could transmit these bacteria within bat populations. To better understand this potential for transmission, we investigated the relatedness between Bartonella detected or isolated from bat hosts sampled in Mexico and their ectoparasites. Bartonella spp. were identified in bat flies collected on two bat species, with the highest prevalence in Trichobius parasiticus and Strebla wiedemanni collected from common vampire bats (Desmodus rotundus). When comparing Bartonella sequences from a fragment of the citrate synthase gene (gltA), vector-associated strains were diverse and generally close to, but distinct from, those recovered from their bacteremic bat hosts in Mexico. Complete Bartonella sequence concordance was observed in only one bat-vector pair. The diversity of Bartonella strains in bat flies reflects the frequent host switch by bat flies, as they usually do not live permanently on their bat host. It may also suggest a possible endosymbiotic relationship with these vectors for some of the Bartonella species carried by bat flies, whereas others could have a mammalian host.

The mosquito battlefield: understanding the mosquito’s molecular weaponry against pathogens

USDA-ARS?s Scientific Manuscript database

This presentation will introduce vector-borne diseases and all the vectors implicated. A focus will be made on the most important vector-borne diseases: Malaria and Dengue. Describing the epidemiology of arboviral diseases, and how each vector responds to protozoan, bacterial and viral pathogens. In...

Childhood parasitic infections endemic to the United States.

PubMed

Barry, Meagan A; Weatherhead, Jill E; Hotez, Peter J; Woc-Colburn, Laila

2013-04-01

Endemic parasitic infections in the United States are more frequent than is commonly perceived. Intestinal parasitic infection with Cryptosporidium, Dientamoeba, and Giardia occurs most often in children in northern states during the summer months. Zoonotic Toxocara and Toxoplasma parasitic infections are more frequent in southern states, in African Americans, and in populations with lower socioeconomic status. Approximately 300, 000 people in the United States have Trypanosoma cruzi infection. Local, vector-borne transmission of T cruzi and Leishmania infections has been documented in southern states. Parasitic diseases endemic to the United States are not uncommon but are understudied. Copyright © 2013 Elsevier Inc. All rights reserved.

Advancing integrated tick management to mitigate burden of tick-borne diseases

USDA-ARS?s Scientific Manuscript database

More than half of the world’s population is at risk of exposure to vector-borne pathogens. Annually, more than 1 billion people are infected and more than 1 million die from vector-borne diseases, including those caused by pathogens transmitted by ticks. The problem with tick borne diseases (TBD) is...

Vector Magnetograph Design

NASA Technical Reports Server (NTRS)

Chipman, Russell A.

1996-01-01

This report covers work performed during the period of November 1994 through March 1996 on the design of a Space-borne Solar Vector Magnetograph. This work has been performed as part of a design team under the supervision of Dr. Mona Hagyard and Dr. Alan Gary of the Space Science Laboratory. Many tasks were performed and this report documents the results from some of those tasks, each contained in the corresponding appendix. Appendices are organized in chronological order.

Mosquito distribution in a saltmarsh: determinants of eggs in a variable environment.

PubMed

Rowbottom, Raylea; Carver, Scott; Barmuta, Leon A; Weinstein, Philip; Allen, Geoff R

2017-06-01

Two saltmarsh mosquitoes dominate the transmission of Ross River virus (RRV, Togoviridae: Alphavirus), one of Australia's most prominent mosquito-borne diseases. Ecologically, saltmarshes vary in their structure, including habitat types, hydrological regimes, and diversity of aquatic fauna, all of which drive mosquito oviposition behavior. Understanding the distribution of vector mosquitoes within saltmarshes can inform early warning systems, surveillance, and management of vector populations. The aim of this study was to identify the distribution of Ae. camptorhynchus, a known vector for RRV, across a saltmarsh and investigate the influence that other invertebrate assemblage might have on Ae. camptorhynchus egg dispersal. We demonstrate that vegetation is a strong indicator for Ae. camptorhynchus egg distribution, and this was not correlated with elevation or other invertebrates located at this saltmarsh. Also, habitats within this marsh are less frequently inundated, resulting in dryer conditions. We conclude that this information can be applied in vector surveillance and monitoring of temperate saltmarsh environments and also provides a baseline for future investigations into understanding mosquito vector habitat requirements. © 2017 The Society for Vector Ecology.

Other vector-borne parasitic diseases: animal helminthiases, bovine besnoitiosis and malaria.

PubMed

Duvallet, G; Boireau, P

2015-08-01

The parasitic diseases discussed elsewhere in this issue of the Scientific and Technical Review are not the only ones to make use of biological vectors (such as mosquitoes or ticks) or mechanical vectors (such as horse flies or Stomoxys flies). The authors discuss two major groups of vector-borne parasitic diseases: firstly, helminthiasis, along with animal filariasis and onchocerciasis, which are parasitic diseases that often take a heavytoll on artiodactylsthroughoutthe world; secondly, parasitic diseases caused by vector-borne protists, foremost of which is bovine besnoitiosis (or anasarca of cattle), which has recently spread through Europe by a dual mode of transmission (direct and by vector). Other protists, such as Plasmodium and Hepatozoon, are also described briefly.

Influence of vectors' risk-spreading strategies and environmental stochasticity on the epidemiology and evolution of vector-borne diseases: the example of Chagas' disease.

PubMed

Pelosse, Perrine; Kribs-Zaleta, Christopher M; Ginoux, Marine; Rabinovich, Jorge E; Gourbière, Sébastien; Menu, Frédéric

2013-01-01

Insects are known to display strategies that spread the risk of encountering unfavorable conditions, thereby decreasing the extinction probability of genetic lineages in unpredictable environments. To what extent these strategies influence the epidemiology and evolution of vector-borne diseases in stochastic environments is largely unknown. In triatomines, the vectors of the parasite Trypanosoma cruzi, the etiological agent of Chagas' disease, juvenile development time varies between individuals and such variation most likely decreases the extinction risk of vector populations in stochastic environments. We developed a simplified multi-stage vector-borne SI epidemiological model to investigate how vector risk-spreading strategies and environmental stochasticity influence the prevalence and evolution of a parasite. This model is based on available knowledge on triatomine biodemography, but its conceptual outcomes apply, to a certain extent, to other vector-borne diseases. Model comparisons between deterministic and stochastic settings led to the conclusion that environmental stochasticity, vector risk-spreading strategies (in particular an increase in the length and variability of development time) and their interaction have drastic consequences on vector population dynamics, disease prevalence, and the relative short-term evolution of parasite virulence. Our work shows that stochastic environments and associated risk-spreading strategies can increase the prevalence of vector-borne diseases and favor the invasion of more virulent parasite strains on relatively short evolutionary timescales. This study raises new questions and challenges in a context of increasingly unpredictable environmental variations as a result of global climate change and human interventions such as habitat destruction or vector control.

Violence in the massage parlor industry: experiences of Canadian-born and immigrant women.

PubMed

Bungay, Vicky; Halpin, Michael; Halpin, Peter F; Johnston, Caitlin; Patrick, David M

2012-01-01

We examined and contrasted 129 Canadian-born and immigrant women's experiences of violence and associated structural and interpersonal factors within indoor commercial sex venues. The majority experienced at least one form of structural, interpersonal, or both types of violence, with the attempted removal of a condom during sexual services being cited most frequently. Canadian-born women reported more frequent violent assaults in the survey data. The women's qualitative narratives illustrated that perceptions of violence differed significantly among Canadian versus non-Canadian born women. Findings concerning racialization and gendered relations of power have important implications for prevention and interventions to support victims of abuse.

Drivers for the emergence and re-emergence of vector-borne protozoal and bacterial diseases.

PubMed

Harrus, S; Baneth, G

2005-10-01

In recent years, vector-borne parasitic and bacterial diseases have emerged or re-emerged in many geographical regions causing global health and economic problems that involve humans, livestock, companion animals and wild life. The ecology and epidemiology of vector-borne diseases are affected by the interrelations between three major factors comprising the pathogen, the host (human, animal or vector) and the environment. Important drivers for the emergence and spread of vector-borne parasites include habitat changes, alterations in water storage and irrigation habits, atmospheric and climate changes, immunosuppression by HIV, pollution, development of insecticide and drug resistance, globalization and the significant increase in international trade, tourism and travel. War and civil unrest, and governmental or global management failure are also major contributors to the spread of infectious diseases. The improvement of epidemic understanding and planning together with the development of new diagnostic molecular techniques in the last few decades have allowed researchers to better diagnose and trace pathogens, their origin and routes of infection, and to develop preventive public health and intervention programs. Health care workers, physicians, veterinarians and biosecurity officers should play a key role in future prevention of vector-borne diseases. A coordinated global approach for the prevention of vector-borne diseases should be implemented by international organizations and governmental agencies in collaboration with research institutions.

It shouldn't happen to a dog … or a veterinarian: clinical paradigms for canine vector-borne diseases.

PubMed

Irwin, Peter J

2014-02-01

Canine vector-borne diseases (CVBDs) comprise a diverse group of viral, bacterial, protozoal, and helminth pathogens, transmitted predominantly by ticks and fleas, and cause significant health problems for dogs worldwide. Growing numbers of reports indicate that CVBDs are emerging in regions where they previously did not exist and this, combined with pathogens that are inherently difficult to detect, is providing companion animal veterinarians with some significant diagnostic challenges. This review discusses six paradigms concerning the diagnosis, treatment, prevention, and zoonotic implications of CVBDs from a veterinary clinical perspective. Copyright © 2013 Elsevier Ltd. All rights reserved.

Range expansion of the Bluetongue vector, Culicoides imicola, in continental France likely due to rare wind-transport events.

PubMed

Jacquet, Stéphanie; Huber, Karine; Pagès, Nonito; Talavera, Sandra; Burgin, Laura E; Carpenter, Simon; Sanders, Christopher; Dicko, Ahmadou H; Djerbal, Mouloud; Goffredo, Maria; Lhor, Youssef; Lucientes, Javier; Miranda-Chueca, Miguel A; Pereira Da Fonseca, Isabel; Ramilo, David W; Setier-Rio, Marie-Laure; Bouyer, Jérémy; Chevillon, Christine; Balenghien, Thomas; Guis, Hélène; Garros, Claire

2016-06-06

The role of the northward expansion of Culicoides imicola Kieffer in recent and unprecedented outbreaks of Culicoides-borne arboviruses in southern Europe has been a significant point of contention. We combined entomological surveys, movement simulations of air-borne particles, and population genetics to reconstruct the chain of events that led to a newly colonized French area nestled at the northern foot of the Pyrenees. Simulating the movement of air-borne particles evidenced frequent wind-transport events allowing, within at most 36 hours, the immigration of midges from north-eastern Spain and Balearic Islands, and, as rare events, their immigration from Corsica. Completing the puzzle, population genetic analyses discriminated Corsica as the origin of the new population and identified two successive colonization events within west-Mediterranean basin. Our findings are of considerable importance when trying to understand the invasion of new territories by expanding species.

Detection of Anaplasma spp. and Ehrlichia spp. anibodies, and Dirofilaria immitis antigens in dogs from seven locations of Morocco.

PubMed

Elhamiani Khatat, Sarah; Khallaayoune, Khalid; Errafyk, Nabil; Van Gool, Frans; Duchateau, Luc; Daminet, Sylvie; Kachani, Malika; El Amri, Hamid; Azrib, Rahma; Sahibi, Hamid

2017-05-30

In Morocco no data has been published on canine exposure to Anaplasma spp., Borrrelia burgdorferi, and Ehrlichia spp., and only one report is available on the occurrence of Dirofilaria immitis in dogs. Therefore, the aim of this study was to collect current data on the canine exposure to these vector-borne pathogens (VBPs) in Morocco. A total of 217 urban (n=57), rural (n=110) and military (n=50) dogs from seven Moroccan locations were screened for Anaplasma spp., B. burgdorferi and Ehrlichia spp. antibodies and for D. immitis antigens using a commercial in-clinic ELISA test. Of these dogs, 182 (83.9%) tested positive for at least one pathogen and positivity to two or three pathogens was found in 14.3% and 2.3% of the dogs, respectively. Ehrlichia spp. antibodies (34.6%) were the most frequently detected followed by Anaplasma spp. antibodies (16.6%) and D. immitis antigens (16.1%). None of the dogs was tested seropositive to B. burgdorferi. Statistically significant differences in seropositivity rates were found for Ehrlichia spp. and D. immitis in rural dogs especially those from the north central region (p<0.001) but not for Anaplasma spp. No significant difference was found according to the health status of the dog. This study demonstrates that Moroccan dogs are at high risk of acquiring a vector-borne infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Climate change, vector-borne diseases and working population.

PubMed

Vonesch, Nicoletta; D'Ovidio, Maria Concetta; Melis, Paola; Remoli, Maria Elena; Ciufolini, Maria Grazia; Tomao, Paola

2016-01-01

Risks associated with climate change are increasing worldwide and the global effects include altered weather and precipitation patterns, rising temperatures and others; human health can be affected directly and indirectly. This paper is an overview of literature regarding climate changes, their interaction with vector-borne diseases and impact on working population. Articles regarding climate changes as drivers of vector-borne diseases and evidences of occupational cases have been picked up by public databank. Technical documents were also included in the study. Evidences regarding the impact of climate changes on vector-borne diseases in Europe, provided by the analysis of the literature, are presented. Climate-sensitive vector-borne diseases are likely to be emerging due to climate modifications, with impacts on public and occupational health. However, other environmental and anthropogenic drivers such as increasing travelling and trade, deforestation and reforestation, altered land use and urbanization can influence their spread. Further studies are necessary to better understand the phenomenon and implementation of adaptation strategies to protect human health should be accelerated and strengthened.

Earth Observation and Indicators Pertaining to Determinants of Health- An Approach to Support Local Scale Characterization of Environmental Determinants of Vector-Borne Diseases

NASA Astrophysics Data System (ADS)

Kotchi, Serge Olivier; Brazeau, Stephanie; Ludwig, Antoinette; Aube, Guy; Berthiaume, Pilippe

2016-08-01

Environmental determinants (EVDs) were identified as key determinant of health (DoH) for the emergence and re-emergence of several vector-borne diseases. Maintaining ongoing acquisition of data related to EVDs at local scale and for large regions constitutes a significant challenge. Earth observation (EO) satellites offer a framework to overcome this challenge. However, EO image analysis methods commonly used to estimate EVDs are time and resource consuming. Moreover, variations of microclimatic conditions combined with high landscape heterogeneity limit the effectiveness of climatic variables derived from EO. In this study, we present what are DoH and EVDs, the impacts of EVDs on vector-borne diseases in the context of global environmental change, the need to characterize EVDs of vector-borne diseases at local scale and its challenges, and finally we propose an approach based on EO images to estimate at local scale indicators pertaining to EVDs of vector-borne diseases.

Tick-borne rickettsial pathogens in questing ticks, removed from humans and animals in Mexico.

PubMed

Sosa-Gutierrez, Carolina G; Vargas-Sandoval, Margarita; Torres, Javier; Gordillo-Pérez, Guadalupe

2016-09-30

Tick-borne rickettsial diseases (TBRD) are commonly encountered in medical and veterinary clinical settings. The control of these diseases is difficult, requiring disruption of a complex transmission chain involving a vertebrate host and ticks. The geographical distribution of the diseases is related to distribution of the vector, which is an indicator of risk for the population. A total of 1107 were collected by tick drag from forests, ecotourism parks and hosts at 101 sites in 22 of the 32 states of Mexico. Collected ticks were placed in 1.5 mL cryovials containing 70% ethanol and were identified to species. Ticks were pooled according to location/host of collection, date of collection, sex, and stage of development. A total of 51 ticks were assayed by polymerase chain reaction (PCR) to confirm species identification using morphological methods. A total of 477 pools of ticks were assayed using PCR techniques for selected tick-borne pathogens. Anaplasma phagocytophilum was the most commonly detected pathogen (45 pools), followed by, Ehrlichia (E.) canis (42), Rickettsia (R.) rickettsii (11), E. chaffeensis (8), and R. amblyommii (1). Rhipicephalus sanguineus was the tick most frequently positive for selected pathogens. Overall, our results indicate that potential tick vectors positive for rickettsial pathogens are distributed throughout the area surveyed in Mexico.

Declining Prevalence of Disease Vectors Under Climate Change

NASA Astrophysics Data System (ADS)

Escobar, Luis E.; Romero-Alvarez, Daniel; Leon, Renato; Lepe-Lopez, Manuel A.; Craft, Meggan E.; Borbor-Cordova, Mercy J.; Svenning, Jens-Christian

2016-12-01

More than half of the world population is at risk of vector-borne diseases including dengue fever, chikungunya, zika, yellow fever, leishmaniasis, chagas disease, and malaria, with highest incidences in tropical regions. In Ecuador, vector-borne diseases are present from coastal and Amazonian regions to the Andes Mountains; however, a detailed characterization of the distribution of their vectors has never been carried out. We estimate the distribution of 14 vectors of the above vector-borne diseases under present-day and future climates. Our results consistently suggest that climate warming is likely threatening some vector species with extinction, locally or completely. These results suggest that climate change could reduce the burden of specific vector species. Other vector species are likely to shift and constrain their geographic range to the highlands in Ecuador potentially affecting novel areas and populations. These forecasts show the need for development of early prevention strategies for vector species currently absent in areas projected as suitable under future climate conditions. Informed interventions could reduce the risk of human exposure to vector species with distributional shifts, in response to current and future climate changes. Based on the mixed effects of future climate on human exposure to disease vectors, we argue that research on vector-borne diseases should be cross-scale and include climatic, demographic, and landscape factors, as well as forces facilitating disease transmission at fine scales.

Distribution of mosquitoes and mosquito-borne arboviruses in Yunnan Province near the China-Myanmar-Laos border.

PubMed

Wang, Jinglin; Zhang, Hailin; Sun, Xiaohong; Fu, Shihong; Wang, Huanqin; Feng, Yun; Wang, Huanyu; Tang, Qing; Liang, Guo-Dong

2011-05-01

Economic development and increased tourism in the southern region of Yunnan Province in China, adjacent to several countries in Southeast Asia, has increased the likelihood of import and export of vectors and vector-borne diseases. We report the results of surveillance of mosquitoes and mosquito-borne arboviruses along the border of China-Myanmar-Laos in 2005 and 2006, and information associating several arboviruses with infections and possibly disease in local human populations. Seventeen mosquito species representing four genera were obtained, and 14 strains of mosquito-borne viruses representing six viruses in five genera were isolated from Culex tritaeniorhynchus. In addition, IgM against Japanese encephalitis virus, Sindbis virus, Yunnan orbivirus and novel Banna virus was detected in acute-phase serum samples obtained from hospitalized patients with fever and encephalitis near the areas where the viruses were isolated. This investigation suggests that Japanese encephalitis virus, Sindbis virus, and lesser-known arboviruses circulate and may be infecting humans in the China-Myanmar-Laos border region.

Influence of Vectors’ Risk-Spreading Strategies and Environmental Stochasticity on the Epidemiology and Evolution of Vector-Borne Diseases: The Example of Chagas’ Disease

PubMed Central

Pelosse, Perrine; Kribs-Zaleta, Christopher M.; Ginoux, Marine; Rabinovich, Jorge E.; Gourbière, Sébastien; Menu, Frédéric

2013-01-01

Insects are known to display strategies that spread the risk of encountering unfavorable conditions, thereby decreasing the extinction probability of genetic lineages in unpredictable environments. To what extent these strategies influence the epidemiology and evolution of vector-borne diseases in stochastic environments is largely unknown. In triatomines, the vectors of the parasite Trypanosoma cruzi, the etiological agent of Chagas’ disease, juvenile development time varies between individuals and such variation most likely decreases the extinction risk of vector populations in stochastic environments. We developed a simplified multi-stage vector-borne SI epidemiological model to investigate how vector risk-spreading strategies and environmental stochasticity influence the prevalence and evolution of a parasite. This model is based on available knowledge on triatomine biodemography, but its conceptual outcomes apply, to a certain extent, to other vector-borne diseases. Model comparisons between deterministic and stochastic settings led to the conclusion that environmental stochasticity, vector risk-spreading strategies (in particular an increase in the length and variability of development time) and their interaction have drastic consequences on vector population dynamics, disease prevalence, and the relative short-term evolution of parasite virulence. Our work shows that stochastic environments and associated risk-spreading strategies can increase the prevalence of vector-borne diseases and favor the invasion of more virulent parasite strains on relatively short evolutionary timescales. This study raises new questions and challenges in a context of increasingly unpredictable environmental variations as a result of global climate change and human interventions such as habitat destruction or vector control. PMID:23951018

Taking the Bite Out of Vector-Borne Diseases

MedlinePlus

... the 'Bite' Out of Vector-Borne Diseases Inside Life Science View All Articles | Inside Life Science Home Page Taking the 'Bite' Out of Vector- ... Science Solving the Sleeping Sickness 'Mystery' This Inside Life Science article also appears on LiveScience . Learn about related ...

Cats are not small dogs: is there an immunological explanation for why cats are less affected by arthropod-borne disease than dogs?

PubMed

Day, Michael J

2016-09-20

It is widely recognized that cats appear to be less frequently affected by arthropod-borne infectious diseases than dogs and share fewer zoonotic pathogens with man. This impression is supported by the relative lack of scientific publications related to feline vector-borne infections. This review explores the possible reasons for the difference between the two most common small companion animal species, including the hypothesis that cats might have a genetically-determined immunological resistance to arthropod vectors or the microparasites they transmit. A number of simple possibilities might account for the lower prevalence of these diseases in cats, including factors related to the lifestyle and behaviour of the cat, lesser spend on preventative healthcare for cats and reduced opportunities for research funding for these animals. The dog and cat have substantially similar immune system components, but differences in immune function might in part account for the markedly distinct prevalence and clinicopathological appearance of autoimmune, allergic, idiopathic inflammatory, immunodeficiency, neoplastic and infectious diseases in the two species. Cats have greater genetic diversity than dogs with much lower linkage disequilibrium in feline compared with canine breed groups. Immune function is intrinsically related to the nature of the intestinal microbiome and subtle differences between the canine and feline microbial populations might also impact on immune function and disease resistance. The reasons for the apparent lesser susceptibility of cats to arthropod-borne infectious diseases are likely to be complex, but warrant further investigation.

Chagas Disease Knowledge and Risk Behaviors of the Homeless Population in Houston, TX.

PubMed

Ingber, Alexandra; Garcia, Melissa N; Leon, Juan; Murray, Kristy O

2018-04-01

Chagas disease is a parasitic infection, caused by Trypanosoma cruzi, endemic in Latin America. Sylvatic T. cruzi-infected triatomine vectors are present in rural and urban areas in the southern USA and may transmit T. cruzi infection to at-risk populations, such as homeless individuals. Our study aimed to evaluate Chagas disease knowledge and behaviors potentially associated with transmission risk of Chagas disease among Houston, Texas' homeless population by performing interviews with 212 homeless individuals. The majority of the 212 surveyed homeless individuals were male (79%), African-American (43%), American-born individuals (96%). About 30% of the individuals reported having seen triatomines in Houston, and 25% had evidence of blood-borne transmission risk (IV drug use and/or unregulated tattoos). The median total time homeless was significantly associated with recognition of the triatomine vector. Our survey responses indicate that the homeless populations may exhibit potential risks for Chagas disease, due to increased vector exposure, and participation in blood-borne pathogen risk behaviors. Our findings warrant additional research to quantify the prevalence of Chagas disease among homeless populations.

Diagnostic approach for monitoring hydroclimatic conditions related to emergence of west nile virus in west virginia.

PubMed

Jutla, Antarpreet; Huq, Anwar; Colwell, Rita R

2015-01-01

West Nile virus (WNV), mosquito-borne and water-based disease, is increasingly a global threat to public health. Since its appearance in the northeastern United States in 1999, WNV has since been reported in several states in the continental United States. The objective of this study is to highlight role of hydroclimatic processes estimated through satellite sensors in capturing conditions for emergence of the vectors in historically disease free regions. We tested the hypothesis that an increase in surface temperature, in combination with intensification of vegetation, and enhanced precipitation, lead to conditions favorable for vector (mosquito) growth. Analysis of land surface temperature (LST) pattern shows that temperature values >16°C, with heavy precipitation, may lead to abundance of the mosquito population. This hypothesis was tested in West Virginia where a sudden epidemic of WNV infection was reported in 2012. Our results emphasize the value of hydroclimatic processes estimated by satellite remote sensing, as well as continued environmental surveillance of mosquitoes, because when a vector-borne infection like WNV is discovered in contiguous regions, the risk of spread of WNV mosquitoes increase at points where appropriate hydroclimatic processes intersect with the vector niche.

Emerging arthropod-borne diseases of companion animals in Europe.

PubMed

Beugnet, Frederic; Marié, Jean-Lou

2009-08-26

Vector-borne diseases are caused by parasites, bacteria or viruses transmitted by the bite of hematophagous arthropods (mainly ticks and mosquitoes). The past few years have seen the emergence of new diseases, or re-emergence of existing ones, usually with changes in their epidemiology (i.e. geographical distribution, prevalence, and pathogenicity). The frequency of some vector-borne diseases of pets is increasing in Europe, i.e. canine babesiosis, granulocytic anaplasmosis, canine monocytic ehrlichiosis, thrombocytic anaplasmosis, and leishmaniosis. Except for the last, these diseases are transmitted by ticks. Both the distribution and abundance of the three main tick species, Rhipicephalus sanguineus, Dermacentor reticulatus and Ixodes ricinus are changing. The conditions for such changes involve primarily human factors, such as travel with pets, changes in human habitats, social and leisure activities, but climate changes also have a direct impact on arthropod vectors (abundance, geographical distribution, and vectorial capacity). Besides the most known diseases, attention should be kept on tick-borne encephalitis, which seems to be increasing in western Europe, as well as flea-borne diseases like the flea-transmitted rickettsiosis. Here, after consideration of the main reasons for changes in tick vector ecology, an overview of each "emerging" vector-borne diseases of pets is presented.

Ecological approaches to informing public health policy and risk assessments on emerging vector-borne zoonoses

PubMed Central

Medlock, JM; Jameson, LJ

2010-01-01

Pathogens associated with vector-borne zoonoses occur in enzootic cycles within nature. They are driven by a combination of vertebrate host and invertebrate vector population dynamics, which in turn respond to changes in environmental stimuli. Human involvement in these cycles, and hence the occurrence of human disease, is often to act as incidental host. From a public health perspective our ability to better predict human outbreaks of these diseases and prepare intervention and mitigation strategies relies on understanding the natural cycle of pathogen transmission. This requires consideration of, for example, invertebrate and vertebrate ecology and biology, climatology, land use and habitat change. Collectively, these can be referred to as medical entomology and medical ecology. This article reviews the importance for inclusion of such disciplines when assessing the public health risk from vector-borne zoonoses and summarizes the possible future challenges and driving forces for changes in vector status and vector-borne zoonoses emergence, with a particular focus on a UK and European context. PMID:22460391

Schools as Potential Risk Sites for Vector-Borne Disease Transmission: Mosquito Vectors in Rural Schools in Two Municipalities in Colombia.

PubMed

Olano, Víctor Alberto; Matiz, María Inés; Lenhart, Audrey; Cabezas, Laura; Vargas, Sandra Lucía; Jaramillo, Juan Felipe; Sarmiento, Diana; Alexander, Neal; Stenström, Thor Axel; Overgaard, Hans J

2015-09-01

Dengue and other vector-borne diseases are of great public health importance in Colombia. Vector surveillance and control activities are often focused at the household level. Little is known about the importance of nonhousehold sites, including schools, in maintaining vector-borne disease transmission. The objectives of this paper were to determine the mosquito species composition in rural schools in 2 municipalities in Colombia and to assess the potential risk of vector-borne disease transmission in school settings. Entomological surveys were carried out in rural schools during the dry and rainy seasons of 2011. A total of 12 mosquito species were found: Aedes aegypti, Anopheles pseudopunctipennis, Culex coronator, Cx. quinquefasciatus, and Limatus durhamii in both immature and adult forms; Ae. fluviatilis, Cx. nigripalpus, Cx. corniger, and Psorophora ferox in immature forms only; and Ae. angustivittatus, Haemagogus equinus, and Trichoprosopon lampropus in adult forms only. The most common mosquito species was Cx. quinquefasciatus. Classrooms contained the greatest abundance of adult female Ae. aegypti and Cx. quinquefasciatus. The most common Ae. aegypti breeding sites were containers classified as "others" (e.g., cans), followed by containers used for water storage. A high level of Ae. aegypti infestation was found during the wet season. Our results suggest that rural schools are potentially important foci for the transmission of dengue and other mosquito-borne diseases. We propose that public health programs should be implemented in rural schools to prevent vector-borne diseases.

Arboviruses and their vectors in the Pacific--status report.

PubMed

Guillaumot, Laurent

2005-09-01

Three arboviruses have already caused epidemics in various Pacific Island countries and territories, and currently represent a direct threat to public health. The diseases concerned are all mosquito-borne and should be kept under careful surveillance. Dengue fever, which is a worldwide major public health problem, is mainly transmitted in the Pacific by the Aedes aegypti vector but also by other mosquitoes of this genus with varying ranges. Epidemic polyarthritis due to the Ross River virus is endemic in Australia. At least one major epidemic has occurred in the Pacific where various vector mosquito species occur. Japanese encephalitis is a zoonosis that can be transmitted to humans by mosquitoes of the genus Culex. Its area of distribution in Asia is expanding and the possibility of fresh incursions into the region should be borne in mind. This paper reviews the situation regarding these diseases in the Pacific and provides information on the way they are transmitted as well as on the biology of the mosquito vectors.

Transgenesis and paratransgenesis to control insect-borne diseases: Current status and future challenges

PubMed Central

Coutinho-Abreu, Iliano V.; Zhu, Kun Yan; Ramalho-Ortigao, Marcelo

2009-01-01

Insect-borne diseases cause significant human morbidity and mortality. Current control and preventive methods against vector-borne diseases rely mainly on insecticides. The emergence of insecticide resistance in many disease vectors highlights the necessity to develop new strategies to control these insects. Vector transgenesis and paratransgenesis are novel strategies that aim at reducing insect vectorial capacity, or seek to eliminate transmission of pathogens such as Plasmodium sp., Trypanosoma sp., and Dengue virus currently being developed. Vector transgenesis relies on direct genetic manipulation of disease vectors making them incapable of functioning as vectors of a given pathogen. Paratransgenesis focuses on utilizing genetically modified insect symbionts to express molecules within the vector that are deleterious to pathogens they transmit. Despite the many successes achieved in developing such techniques in the last several years, many significant barriers remain and need to be overcome prior to any of these approaches become a reality. Here, we highlight the current status of these strategies, pointing out advantages and constraints, and also explore issues that need to be resolved before the establishment of transgenesis and paratransgenesis as tools to prevent vector-borne diseases. PMID:19819346

Prevalence of Vector-Borne Pathogens in Southern California Dogs With Clinical and Laboratory Abnormalities Consistent With Immune-Mediated Disease.

PubMed

Kidd, L; Qurollo, B; Lappin, M; Richter, K; Hart, J R; Hill, S; Osmond, C; Breitschwerdt, E B

2017-07-01

Studies investigating the prevalence of vector-borne pathogens in southern California dogs are limited. Occult infections might be misdiagnosed as idiopathic immune-mediated disease. (1) To determine the prevalence of vector-borne pathogens in southern California dogs with compatible clinical findings using PCR and serologic panels and (2) to determine whether testing convalescent samples and repeating PCR on acute samples using the same and different gene targets enhance detection. Forty-two client-owned dogs with clinical signs of vector-borne disease presenting to specialty practices in San Diego County. Combined prospective and retrospective observational study. Forty-two acute and 27 convalescent samples were collected. Acute samples were prospectively tested for antibodies to Rickettsia, Ehrlichia, Bartonella, Babesia, Borrelia, and Anaplasma species. PCR targeting Ehrlichia, Babesia, Anaplasma, hemotropic Mycoplasma, and Bartonella species was also performed. Retrospectively, convalescent samples were tested for the same organisms using serology, and for Ehrlichia, Babesia, Anaplasma, and Bartonella species using PCR. Acute samples were retested using PCR targeting Ehrlichia and Babesia species. Evidence of exposure to or infection with a vector-borne pathogen was detected in 33% (14/42) of dogs. Ehrlichia and Babesia species were most common; each was identified in 5 dogs. Convalescent serologic testing, repeating PCR, and using novel PCR gene targets increased detection by 30%. Repeated testing using serology and PCR enhances detection of infection by vector-borne pathogens in dogs with clinical signs of immune-mediated disease. Larger prevalence studies of emerging vector-borne pathogens in southern California dogs are warranted. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Protection of Military Personnel Against Vector-Borne Diseases: A Review of Collaborative Work of the Australian and US Military Over the Last 30 Years.

PubMed

Frances, Stephen P; Edstein, Michael D; Debboun, Mustapha; Shanks, G Dennis

2016-01-01

Australian and US military medical services have collaborated since World War II to minimize vector-borne diseases such as malaria, dengue, and scrub typhus. In this review, collaboration over the last 30 years is discussed. The collaborative projects and exchange scientist programs have resulted in mutually beneficial outcomes in the fields of drug development and personal protection measures against vector-borne diseases.

Using the Gravity Model to Estimate the Spatial Spread of Vector-Borne Diseases

PubMed Central

Barrios, José Miguel; Verstraeten, Willem W.; Maes, Piet; Aerts, Jean-Marie; Farifteh, Jamshid; Coppin, Pol

2012-01-01

The gravity models are commonly used spatial interaction models. They have been widely applied in a large set of domains dealing with interactions amongst spatial entities. The spread of vector-borne diseases is also related to the intensity of interaction between spatial entities, namely, the physical habitat of pathogens’ vectors and/or hosts, and urban areas, thus humans. This study implements the concept behind gravity models in the spatial spread of two vector-borne diseases, nephropathia epidemica and Lyme borreliosis, based on current knowledge on the transmission mechanism of these diseases. Two sources of information on vegetated systems were tested: the CORINE land cover map and MODIS NDVI. The size of vegetated areas near urban centers and a local indicator of occupation-related exposure were found significant predictors of disease risk. Both the land cover map and the space-borne dataset were suited yet not equivalent input sources to locate and measure vegetated areas of importance for disease spread. The overall results point at the compatibility of the gravity model concept and the spatial spread of vector-borne diseases. PMID:23202882

Using the gravity model to estimate the spatial spread of vector-borne diseases.

PubMed

Barrios, José Miguel; Verstraeten, Willem W; Maes, Piet; Aerts, Jean-Marie; Farifteh, Jamshid; Coppin, Pol

2012-11-30

The gravity models are commonly used spatial interaction models. They have been widely applied in a large set of domains dealing with interactions amongst spatial entities. The spread of vector-borne diseases is also related to the intensity of interaction between spatial entities, namely, the physical habitat of pathogens’ vectors and/or hosts, and urban areas, thus humans. This study implements the concept behind gravity models in the spatial spread of two vector-borne diseases, nephropathia epidemica and Lyme borreliosis, based on current knowledge on the transmission mechanism of these diseases. Two sources of information on vegetated systems were tested: the CORINE land cover map and MODIS NDVI. The size of vegetated areas near urban centers and a local indicator of occupation-related exposure were found significant predictors of disease risk. Both the land cover map and the space-borne dataset were suited yet not equivalent input sources to locate and measure vegetated areas of importance for disease spread. The overall results point at the compatibility of the gravity model concept and the spatial spread of vector-borne diseases.

Global Climate Teleconnections to Forecast Increased Risk of Vector-Borne Animal and Human Disease Transmission

USDA-ARS?s Scientific Manuscript database

We willexamine how climate teleconnect ions and variability impact vector biology and vector borne disease ecology, and demonstrate that global climate monitoring can be used to anticipate and forecast epidemics and epizootics. In this context we willexamine significant worldwide weather anomalies t...

From puddles to planet: modeling approaches to vector-borne diseases at varying resolution and scale.

PubMed

Eckhoff, Philip A; Bever, Caitlin A; Gerardin, Jaline; Wenger, Edward A; Smith, David L

2015-08-01

Since the original Ross-Macdonald formulations of vector-borne disease transmission, there has been a broad proliferation of mathematical models of vector-borne disease, but many of these models retain most to all of the simplifying assumptions of the original formulations. Recently, there has been a new expansion of mathematical frameworks that contain explicit representations of the vector life cycle including aquatic stages, multiple vector species, host heterogeneity in biting rate, realistic vector feeding behavior, and spatial heterogeneity. In particular, there are now multiple frameworks for spatially explicit dynamics with movements of vector, host, or both. These frameworks are flexible and powerful, but require additional data to take advantage of these features. For a given question posed, utilizing a range of models with varying complexity and assumptions can provide a deeper understanding of the answers derived from models. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Fatal Flea-Borne Typhus in Texas: A Retrospective Case Series, 1985-2015.

PubMed

Pieracci, Emily G; Evert, Nicole; Drexler, Naomi A; Mayes, Bonny; Vilcins, Inger; Huang, Philip; Campbell, Jill; Behravesh, Casey Barton; Paddock, Christopher D

2017-05-01

AbstractFlea-borne (murine) typhus is a global rickettsiosis caused by Rickettsia typhi . Although flea-borne typhus is no longer nationally notifiable, cases are reported for surveillance purposes in a few U.S. states. The infection is typically self-limiting, but may be severe or life-threatening in some patients. We performed a retrospective review of confirmed or probable cases of fatal flea-borne typhus reported to the Texas Department of State Health Services during 1985-2015. When available, medical charts were also examined. Eleven cases of fatal flea-borne typhus were identified. The median patient age was 62 years (range, 36-84 years) and 8 (73%) were male. Patients presented most commonly with fever (100%), nausea and vomiting (55%), and rash (55%). Respiratory (55%) and neurologic (45%) manifestations were also identified frequently. Laboratory abnormalities included thrombocytopenia (82%) and elevated hepatic transaminases (63%). Flea or animal contact before illness onset was frequently reported (55%). The median time from hospitalization to administration of a tetracycline-class drug was 4 days (range, 0-5 days). The median time from symptom onset to death was 14 days (range, 1-34 days). Flea-borne typhus can be a life-threatening disease if not treated in a timely manner with appropriate tetracycline-class antibiotics. Flea-borne typhus should be considered in febrile patients with animal or flea exposure and respiratory or neurologic symptoms of unknown etiology.

The Absolute Vector Magnetometers on Board Swarm, Lessons Learned From Two Years in Space.

NASA Astrophysics Data System (ADS)

Hulot, G.; Leger, J. M.; Vigneron, P.; Brocco, L.; Olsen, N.; Jager, T.; Bertrand, F.; Fratter, I.; Sirol, O.; Lalanne, X.

2015-12-01

ESA's Swarm satellites carry 4He absolute magnetometers (ASM), designed by CEA-Léti and developed in partnership with CNES. These instruments are the first-ever space-born magnetometers to use a common sensor to simultaneously deliver 1Hz independent absolute scalar and vector readings of the magnetic field. They have provided the very high accuracy scalar field data nominally required by the mission (for both science and calibration purposes, since each satellite also carries a low noise high frequency fluxgate magnetometer designed by DTU), but also very useful experimental absolute vector data. In this presentation, we will report on the status of the instruments, as well as on the various tests and investigations carried out using these experimental data since launch in November 2013. In particular, we will illustrate the advantages of flying ASM instruments on space-born magnetic missions for nominal data quality checks, geomagnetic field modeling and science objectives.

Spread of Vector-borne Diseases and Neglect of Leishmaniasis, Europe

PubMed Central

Campino, Lenea; Cañavate, Carmen; Dedet, Jean-Pierre; Gradoni, Luigi; Soteriadou, Ketty; Mazeris, Apostolos; Ozbel, Yusuf; Boelaert, Marleen

2008-01-01

The risk for reintroduction of some exotic vector-borne diseases in Europe has become a hot topic, while the reality of others is neglected at the public health policy level. Leishmaniasis is endemic in all southern countries of Europe, with ≈700 autochthonous human cases reported each year (3,950 if Turkey is included). Asymptomatic cases have been estimated at 30–100/1 symptomatic case, and leishmaniasis has up to 25% seroprevalence in domestic dogs. Even though leishmaniasis is essentially associated with Leishmania infantum and visceral leishmaniasis, new species, such as L. donovani and L. tropica, might colonize European sand fly vectors. Drug-resistant L. infantum strains might be exported outside Europe through dogs. Despite this possibility, no coordinated surveillance of the disease exists at the European level. In this review of leishmaniasis importance in Europe, we would like to bridge the gap between research and surveillance and control. PMID:18598618

Human fascioliasis in South Africa.

PubMed

Black, J; Ntusi, N; Stead, P; Mayosi, B; Mendelson, M

2013-07-29

Human fascioliasis has the widest latitudinal, longitudinal and altitudinal distribution of any vector-borne disease, yet only 3 cases have been reported from South Africa, the last in 1964. We report 2 cases from the same geographic area associated with local consumption of watercress, suggesting an endemic focus. 

Blocking transmission of vector-borne diseases.

PubMed

Schorderet-Weber, Sandra; Noack, Sandra; Selzer, Paul M; Kaminsky, Ronald

2017-04-01

Vector-borne diseases are responsible for significant health problems in humans, as well as in companion and farm animals. Killing the vectors with ectoparasitic drugs before they have the opportunity to pass on their pathogens could be the ideal way to prevent vector borne diseases. Blocking of transmission might work when transmission is delayed during blood meal, as often happens in ticks. The recently described systemic isoxazolines have been shown to successfully prevent disease transmission under conditions of delayed pathogen transfer. However, if the pathogen is transmitted immediately at bite as it is the case with most insects, blocking transmission becomes only possible if ectoparasiticides prevent the vector from landing on or, at least, from biting the host. Chemical entities exhibiting repellent activity in addition to fast killing, like pyrethroids, could prevent pathogen transmission even in cases of immediate transfer. Successful blocking depends on effective action in the context of the extremely diverse life-cycles of vectors and vector-borne pathogens of medical and veterinary importance which are summarized in this review. This complexity leads to important parameters to consider for ectoparasiticide research and when considering the ideal drug profile for preventing disease transmission. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Seven challenges for modelling indirect transmission: Vector-borne diseases, macroparasites and neglected tropical diseases

PubMed Central

Hollingsworth, T. Déirdre; Pulliam, Juliet R.C.; Funk, Sebastian; Truscott, James E.; Isham, Valerie; Lloyd, Alun L.

2015-01-01

Many of the challenges which face modellers of directly transmitted pathogens also arise when modelling the epidemiology of pathogens with indirect transmission – whether through environmental stages, vectors, intermediate hosts or multiple hosts. In particular, understanding the roles of different hosts, how to measure contact and infection patterns, heterogeneities in contact rates, and the dynamics close to elimination are all relevant challenges, regardless of the mode of transmission. However, there remain a number of challenges that are specific and unique to modelling vector-borne diseases and macroparasites. Moreover, many of the neglected tropical diseases which are currently targeted for control and elimination are vector-borne, macroparasitic, or both, and so this article includes challenges which will assist in accelerating the control of these high-burden diseases. Here, we discuss the challenges of indirect measures of infection in humans, whether through vectors or transmission life stages and in estimating the contribution of different host groups to transmission. We also discuss the issues of “evolution-proof” interventions against vector-borne disease. PMID:25843376

Seven challenges for modelling indirect transmission: vector-borne diseases, macroparasites and neglected tropical diseases.

PubMed

Hollingsworth, T Déirdre; Pulliam, Juliet R C; Funk, Sebastian; Truscott, James E; Isham, Valerie; Lloyd, Alun L

2015-03-01

Many of the challenges which face modellers of directly transmitted pathogens also arise when modelling the epidemiology of pathogens with indirect transmission--whether through environmental stages, vectors, intermediate hosts or multiple hosts. In particular, understanding the roles of different hosts, how to measure contact and infection patterns, heterogeneities in contact rates, and the dynamics close to elimination are all relevant challenges, regardless of the mode of transmission. However, there remain a number of challenges that are specific and unique to modelling vector-borne diseases and macroparasites. Moreover, many of the neglected tropical diseases which are currently targeted for control and elimination are vector-borne, macroparasitic, or both, and so this article includes challenges which will assist in accelerating the control of these high-burden diseases. Here, we discuss the challenges of indirect measures of infection in humans, whether through vectors or transmission life stages and in estimating the contribution of different host groups to transmission. We also discuss the issues of "evolution-proof" interventions against vector-borne disease. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Demand-supply gaps in human resources to combat vector-borne disease in India: capacity-building measures in medical entomology.

PubMed

Pandey, Anuja; Zodpey, Sanjay; Kumar, Raj

2015-01-01

Vector-borne diseases account for a significant proportion of the global burden of infectious disease. They are one of the greatest contributors to human mortality and morbidity in tropical settings, including India. The World Health Organization declared vector-borne diseases as theme for the year 2014, and thus called for renewed commitment to their prevention and control. Human resources are critical to support public health systems, and medical entomologists play a crucial role in public health efforts to combat vector-borne diseases. This paper aims to review the capacity-building initiatives in medical entomology in India, to understand the demand and supply of medical entomologists, and to give future direction for the initiation of need-based training in the country. A systematic, predefined approach, with three parallel strategies, was used to collect and assemble the data regarding medical entomology training in India and assess the demand-supply gap in medical entomologists in the country. The findings suggest that, considering the high burden of vector-borne diseases in the country and the growing need of health manpower specialized in medical entomology, the availability of specialized training in medical entomology is insufficient in terms of number and intake capacity. The demand analysis of medical entomologists in India suggests a wide gap in demand and supply, which needs to be addressed to cater for the burden of vector-borne diseases in the country.

[Important vector-borne infectious diseases among humans in Germany. Epidemiological aspects].

PubMed

Frank, C; Faber, M; Hellenbrand, W; Wilking, H; Stark, K

2014-05-01

Vector-borne infections pathogenic to humans play an important role in Germany. The relevant zoonotic pathogens are either endemic throughout Germany (e.g. Borrelia burgdorferi sensu latu) or only in specific regions, e.g. tick-borne encephalitis (TBE) virus and hantavirus. They cause a substantial burden of disease. Prevention and control largely rely on public advice and the application of personal protective measures (e.g. TBE virus vaccination and protection against vectors). High quality surveillance and targeted epidemiological studies are fundamental for the evaluation of temporal and spatial risks of infection and the effectiveness of preventive measures. Aside from endemic pathogens, vector-borne infections acquired abroad, mostly transmitted by mosquitoes, have to be systematically and intensively monitored as well, to assess the risk of infection for German residents traveling abroad and to adequately evaluate the risk of autochthonous transmission. Related issues, such as invasive species of mosquitoes in Germany and climate change, have to be taken into consideration. Such pathogens include West Nile, dengue and chikungunya viruses, as well as malaria parasites (Plasmodium species). The article presents an overview of the epidemiological situation of selected relevant vector-borne infections in Germany.

Anthropogenic disturbance and the risk of flea-borne disease transmission

Treesearch

Megan M. Friggens; Paul Beier

2010-01-01

Anthropogenic disturbance may lead to the spread of vector-borne diseases through effects on pathogens, vectors, and hosts. Identifying the type and extent of vector response to habitat change will enable better and more accurate management strategies for anthropogenic disease spread. We compiled and analyzed data from published empirical studies to test for patterns...

Remote sensing, global warming, and vector-borne disease

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

Wood, B.; Beck, L.; Dister, S.

1997-12-31

The relationship between climate change and the pattern of vector-borne disease can be viewed at a variety of spatial and temporal scales. At one extreme are changes such as global warming, which are continental in scale and occur over periods of years, decades, or longer. At the opposite extreme are changes associated with severe weather events, which can occur at local and regional scales over periods of days, weeks, or months. Key ecological factors affecting the distribution of vector-borne diseases include temperature, precipitation, and habitat availability, and their impact on vectors, pathogens, reservoirs, and hosts. Global warming can potentially altermore » these factors, thereby affecting the spatial and temporal patterns of disease.« less

COMMUNITY LEVEL ANALYSIS OF VECTOR-BORNE DISEASE

EPA Science Inventory

Ecological community structure is particularly important in vector-borne zoonotic diseases with complex life cycles. Single population models, such as the so-called Ross-Macdonald model (Baily, 1982), have been important in developing and characterizing our current understanding...

Fatal Flea-Borne Typhus in Texas: A Retrospective Case Series, 1985–2015

PubMed Central

Pieracci, Emily G.; Evert, Nicole; Drexler, Naomi A.; Mayes, Bonny; Vilcins, Inger; Huang, Philip; Campbell, Jill; Behravesh, Casey Barton; Paddock, Christopher D.

2017-01-01

Flea-borne (murine) typhus is a global rickettsiosis caused by Rickettsia typhi. Although flea-borne typhus is no longer nationally notifiable, cases are reported for surveillance purposes in a few U.S. states. The infection is typically self-limiting, but may be severe or life-threatening in some patients. We performed a retrospective review of confirmed or probable cases of fatal flea-borne typhus reported to the Texas Department of State Health Services during 1985–2015. When available, medical charts were also examined. Eleven cases of fatal flea-borne typhus were identified. The median patient age was 62 years (range, 36–84 years) and 8 (73%) were male. Patients presented most commonly with fever (100%), nausea and vomiting (55%), and rash (55%). Respiratory (55%) and neurologic (45%) manifestations were also identified frequently. Laboratory abnormalities included thrombocytopenia (82%) and elevated hepatic transaminases (63%). Flea or animal contact before illness onset was frequently reported (55%). The median time from hospitalization to administration of a tetracycline-class drug was 4 days (range, 0–5 days). The median time from symptom onset to death was 14 days (range, 1–34 days). Flea-borne typhus can be a life-threatening disease if not treated in a timely manner with appropriate tetracycline-class antibiotics. Flea-borne typhus should be considered in febrile patients with animal or flea exposure and respiratory or neurologic symptoms of unknown etiology. PMID:28500797

Five cases of vector-borne Francisella tularensis holarctica infections in south-western Germany and genetic diversity.

PubMed

Borde, Johannes P; Zange, Sabine; Antwerpen, Markus H; Georgi, Enrico; von Buttlar, Heiner; Kern, Winfried V; Rieg, Siegbert

2017-08-01

Tularemia is a rare zoonotic disease in Germany. Francisella tularensis has been isolated previously from ticks in southern Germany underscoring the importance of ticks (Ixodes ricinus) in tularemia transmission, but there have been only few reports from this region with single cases or small case series of tick-borne transmissions of tularemia. We report five cases of non-game animal associated tularemia diagnosed from 2010 to 2016 in southwestern Germany - Baden-Wuerttemberg. Our case series and molecular typing (MLVA) results add published clinical experience to this underdiagnosed disease and consolidate previous findings regarding tick-borne transmission of tularemia and phylogenetic diversity in Germany. Copyright © 2017 Elsevier GmbH. All rights reserved.

Lyme borreliosis in dogs and cats: background, diagnosis, treatment and prevention of infections with Borrelia burgdorferi sensu stricto.

PubMed

Krupka, Inke; Straubinger, Reinhard K

2010-11-01

Lyme borreliosis (LB), synonymous with the often-used term Lyme disease, is an infectious disease caused by the spirochetal bacterium Borrelia burgdorferi. LB is the most frequent vector-borne disease in humans in the Northern Hemisphere. In animals, clinically apparent disease is found primarily in dogs. Severe polyarthritis, fever and lameness in dogs are reported from the main endemic areas of North America: the New England States, and eastern parts of the United States; several cases of LB are also seen in California and the Midwest. Because of the difficulties in finding sufficient indicative clinical signs, additional information (detailed case history, laboratory testing for antibodies) is especially important to make the clinical diagnosis of Lyme borreliosis. This article reviews the etiology, diagnosis, therapy, and prevention of LB. Copyright © 2010 Elsevier Inc. All rights reserved.

Cutaneous Leishmaniasis with HIV.

PubMed

Talat, Humaira; Attarwala, Sharmeen; Saleem, Mubasshir

2014-05-01

Cutaneous Leishmaniasis (CL) is a vector borne disease caused by various species of the Leishmania parasite. CL is endemic in the province of Balochistan in Pakistan. In certain instances a Human Immunodeficiency Virus (HIV)-related immunocompromised is associated with atypical clinical presentation and occurrence of reactivated lesions of CL. Such presentations respond poorly to the standard treatment and frequent relapses are noted. We are reporting three cases of localized and disseminated CL due to Leishmania tropica which responded to meglumine antimoniate. Due to the fact that CL is endemic in Balochistan, we did not consider HIV infection as a causative organism. It was their presentation with history of weight loss and fever that prompted Enzyme-linked Immunosorbent Assay (ELISA) tests for HIV, which turned out to be positive. CL is becoming visible as an opportunistic infection associated with HIV/AIDS and may even be the first symptom in HIV positive patients in an endemic area.

Tick repellents and acaricides of botanical origin: a green roadmap to control tick-borne diseases?

PubMed

Benelli, Giovanni; Pavela, Roman; Canale, Angelo; Mehlhorn, Heinz

2016-07-01

Arthropods are dangerous vectors of agents of deadly diseases, which may hit as epidemics or pandemics in the increasing world population of humans and animals. Among them, ticks transmit more pathogen species than any other group of blood-feeding arthropods worldwide. Thus, the effective and eco-friendly control of tick vectors in a constantly changing environment is a crucial challenge. A number of novel routes have been attempted to prevent and control tick-borne diseases, including the development of (i) vaccines against viruses vectored by ticks; (ii) pheromone-based control tools, with special reference to the "lure and kill" techniques; (iii) biological control programmes relying on ticks' natural enemies and pathogens; and (iv) the integrated pest management practices aimed at reducing tick interactions with livestock. However, the extensive employment of acaricides and tick repellents still remains the two most effective and ready-to-use strategies. Unfortunately, the first one is limited by the rapid development of resistance in ticks, as well as by serious environmental concerns. On the other hand, the exploitation of plants as sources of effective tick repellents is often promising. Here, we reviewed current knowledge concerning the effectiveness of plant extracts as acaricides or repellents against tick vectors of public health importance, with special reference to Ixodes ricinus, Ixodes persulcatus, Amblyomma cajennense, Haemaphysalis bispinosa, Haemaphysalis longicornis, Hyalomma anatolicum, Hyalomma marginatum rufipes, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) microplus, Rhipicephalus pulchellus, Rhipicephalus sanguineus and Rhipicephalus turanicus. Eighty-three plant species from 35 botanical families were selected. The most frequent botanical families exploited as sources of acaricides and repellents against ticks were Asteraceae (15 % of the selected studies), Fabaceae (9 %), Lamiaceae (10 %), Meliaceae (5 %), Solanaceae (6 %) and Verbenaceae (5 %). Regression equation analyses showed that the literature grew by approximately 20 % per year (period: 2005-2015). Lastly, in the final section, insights for future research are discussed. We focused on some caveats for future data collection and analysis. Current critical points mainly deal with (a) not uniform methods used, which prevent proper comparison of the results; (b) inaccurate tested concentrations, frequently 100 % concentration corresponded to the gross extract, where the exact amounts of extracted substances are unknown; and (c) not homogeneous size of tested tick instars and species. Overall, the knowledge summarized in this review may be helpful for comparative screening among extensive numbers of plant-borne preparations, in order to develop newer and safer tick control tools.

Remote Sensing Proxies for Vector-borne Disease Risk Assessment (Invited)

NASA Astrophysics Data System (ADS)

Anyamba, A.

2010-12-01

The spread of re-emerging vector-borne diseases such Rift Valley fever (RVF) and Chikungunya (CHIK) is a major issue of global public health concern. This combined with a variable climate regime has opened an avenue for satellite remote sensing to contribute towards a comprehensive understanding of some of the drivers influencing such vector-borne disease outbreaks. Satellite derived measurements such as vegetation indices, rainfall estimates, and land-surface temperature; can be used to infer the complex mosaic of factors that influence ecology and habitat suitability, emergence and population dynamics of disease vectors. However, there are still some gaps in application including appropriate temporal resolution of remote sensing measurements, the complexity of the virus-vector-disease-ecology system and human components that contribute to disease risk that need to be addressed. Geographic Distribution of Recent Rift Valley fever oubreaks

Fleas, hosts and habitat: What can we predict about the spread of vector-borne zoonotic diseases?

Treesearch

Megan M. Friggens

2010-01-01

Vector-borne diseases of humans and wildlife are experiencing resurgence across the globe. I examine the dynamics of flea borne diseases through a comparative analysis of flea literature and analyses of field data collected from three sites in New Mexico: The Sevilleta National Wildlife Refuge, the Sandia Mountains and the Valles Caldera National Preserve (VCNP). My...

Zoonotic aspects of vector-borne infections.

PubMed

Failloux, A-B; Moutailler, S

2015-04-01

Vector-borne diseases are principally zoonotic diseases transmitted to humans by animals. Pathogens such as bacteria, parasites and viruses are primarily maintained within an enzootic cycle between populations of non-human primates or other mammals and largely non-anthropophilic vectors. This 'wild' cycle sometimes spills over in the form of occasional infections of humans and domestic animals. Lifestyle changes, incursions by humans into natural habitats and changes in agropastoral practices create opportunities that make the borders between wildlife and humans more permeable. Some vector-borne diseases have dispensed with the need for amplification in wild or domestic animals and they can now be directly transmitted to humans. This applies to some viruses (dengue and chikungunya) that have caused major epidemics. Bacteria of the genus Bartonella have reduced their transmission cycle to the minimum, with humans acting as reservoir, amplifier and disseminator. The design of control strategies for vector-borne diseases should be guided by research into emergence mechanisms in order to understand how a wild cycle can produce a pathogen that goes on to cause devastating urban epidemics.

Survey of spatial distribution of vector-borne disease in neighborhood dogs in southern Brazil.

PubMed

Constantino, Caroline; de Paula, Edson Ferraz Evaristo; Brandão, Ana Pérola Drulla; Ferreira, Fernando; Vieira, Rafael Felipe da Costa; Biondo, Alexander Welker

2017-01-01

Neighborhood dogs may act as reservoirs and disseminators of vector-borne diseases in urban areas. Accordingly, the aim of this study was to ascertain the health status and the vector-borne pathogens infecting dogs living in public areas with high levels of human movement in the city of Curitiba, southern Brazil. Blood samples from 21 neighborhood dogs that were found in nine of 22 bus stations and two public parks were subjected to a complete blood cell (CBC) count, serum biochemical profiling, a commercial rapid ELISA test and a commercial real-time PCR panel of vector-borne diseases. The CBC count and serum biochemical profiling were within the normal range for dogs and only 1/21 (4.7%) of the dogs was seroreactive for Borrelia burgdorferi sensu stricto. The commercial real-time PCR panel showed that 7/21 (33.3%) of the dogs had Mycoplasma haemocanis infection, 9/21 (42.8%) had ' Candidatus Mycoplasma haematoparvum' and 4/21 (19.0%) had both. No statistical association between infected by the agents found here and abnormalities in physical examinations, laboratory tests or ectoparasite presence was found ( p > 0.05). In conclusion, neighborhood dogs showed low prevalence of vector-borne diseases and satisfactory wellbeing, and dogs can be used as sentinels for disease exposure.

A Reaction-Diffusion Model of Vector-Borne Disease with Periodic Delays

NASA Astrophysics Data System (ADS)

Wu, Ruiwen; Zhao, Xiao-Qiang

2018-06-01

A vector-borne disease is caused by a range of pathogens and transmitted to hosts through vectors. To investigate the multiple effects of the spatial heterogeneity, the temperature sensitivity of extrinsic incubation period and intrinsic incubation period, and the seasonality on disease transmission, we propose a nonlocal reaction-diffusion model of vector-borne disease with periodic delays. We introduce the basic reproduction number R_0 for this model and then establish a threshold-type result on its global dynamics in terms of R_0 . In the case where all the coefficients are constants, we also prove the global attractivity of the positive constant steady state when R_0>1 . Numerically, we study the malaria transmission in Maputo Province, Mozambique.

Incidence of Vector-borne Disease and Climate Change: A Study in Semi-arid Algeria

NASA Astrophysics Data System (ADS)

Blakey, T.; Bounoua, L.

2012-12-01

Leishmaniases are among the most important emerging and resurging vector-borne diseases, second only to malaria in terms of the number of affected people. Leishmaniases are endemic in 88 countries worldwide and threaten about 350 million people (WHO, 2007). Since the first reported case of zoonotic cutaneous leishmaniasis (ZCL) in Saida, Algeria in 1991, 1,275 cases have been recorded (Makhlouf & Houti, 2010) with the vast majority of study-area cases (99%) reported between the years of 2000 and 2009. An investigation of potential climatic indicators for the apparent shift in disease prevalence was conducted by comparing anomalies in the climate data specific to the local pathogen cycle. It was determined that long term climate trends have resulted in conditions that promote the prevalence of ZCL. Increased precipitation have resulted in greater vegetation and promoted host and vector population growth through a trophic cascade. Increased minimum temperatures have lengthened the annual duration of sandfly activity. Short term variations in maximum temperatures, however show a correlation with disease suppression in the subsequent years. These findings indicate a potential to forecast the risk of ZCL infection through models of the trophic cascade and sandfly population growth.

Extreme Weather Events and Impacts on Vector-borne Diseases and Agriculture

USDA-ARS?s Scientific Manuscript database

Extreme weather events during the period 2010-2012 impacted agriculture and vector-borne disease throughout the world. We evaluated specific weather events with satellite remotely sensed environmental data and evaluated crop production and diseases associated with these events. Significant droughts ...

Integrating vector control across diseases.

PubMed

Golding, Nick; Wilson, Anne L; Moyes, Catherine L; Cano, Jorge; Pigott, David M; Velayudhan, Raman; Brooker, Simon J; Smith, David L; Hay, Simon I; Lindsay, Steve W

2015-10-01

Vector-borne diseases cause a significant proportion of the overall burden of disease across the globe, accounting for over 10 % of the burden of infectious diseases. Despite the availability of effective interventions for many of these diseases, a lack of resources prevents their effective control. Many existing vector control interventions are known to be effective against multiple diseases, so combining vector control programmes to simultaneously tackle several diseases could offer more cost-effective and therefore sustainable disease reductions. The highly successful cross-disease integration of vaccine and mass drug administration programmes in low-resource settings acts a precedent for cross-disease vector control. Whilst deliberate implementation of vector control programmes across multiple diseases has yet to be trialled on a large scale, a number of examples of 'accidental' cross-disease vector control suggest the potential of such an approach. Combining contemporary high-resolution global maps of the major vector-borne pathogens enables us to quantify overlap in their distributions and to estimate the populations jointly at risk of multiple diseases. Such an analysis shows that over 80 % of the global population live in regions of the world at risk from one vector-borne disease, and more than half the world's population live in areas where at least two different vector-borne diseases pose a threat to health. Combining information on co-endemicity with an assessment of the overlap of vector control methods effective against these diseases allows us to highlight opportunities for such integration. Malaria, leishmaniasis, lymphatic filariasis, and dengue are prime candidates for combined vector control. All four of these diseases overlap considerably in their distributions and there is a growing body of evidence for the effectiveness of insecticide-treated nets, screens, and curtains for controlling all of their vectors. The real-world effectiveness of cross-disease vector control programmes can only be evaluated by large-scale trials, but there is clear evidence of the potential of such an approach to enable greater overall health benefit using the limited funds available.

Serological and molecular prevalence of canine vector-borne diseases (CVBDs) in Korea.

PubMed

Suh, Guk-Hyun; Ahn, Kyu-Sung; Ahn, Jong-Ho; Kim, Ha-Jung; Leutenegger, Christian; Shin, SungShik

2017-03-16

Previous surveys in dogs from Korea indicated that dogs are exposed to a variety of vector- borne pathogens, but perception for a nation-wide canine vector-borne disease (CVBD) occurrence has been missing. We report here results of both serological and molecular prevalence studies for major CVBDs of dogs from all over the South Korean Peninsula except for Jeju Island. Serological survey of 532 outdoor dogs revealed the highest prevalence for Dirofilaria immitis (25.2%), followed by Anaplasma phagocytophilum (15.6%), Ehrlichia canis (4.7%) whereas Borrelia burgdorferi showed the lowest prevalence (1.1%). The number of serologically positive dogs for any of the four pathogens was 216 (40.6%). Concurrent real-time PCR assay of 440 dogs in the study indicated that DNA of "Candidatus M. haematoparvum", Mycoplasma haemocanis, Babesia gibsoni, A. phagocytophilum, and Hepatozoon canis was identified in 190 (43.2%), 168 (38.2%), 23 (5.2%), 10 (2.3%) and 1 (0.2%) dogs, respectively. DNA of Bartonella spp., Ehrlichia spp., Leishmania spp., Rickettsia spp. and Neorickettsia risticii was not identified. Analysis of questionnaires collected from owners of 440 dogs showed that the number of dogs with heartworm preventive medication was 348 (79.1%) among which dogs still positive to D. immitis infection were 60 (17.2%), probably due to the mean months of heartworm preventive medication being only 6.5. The high prevalence rates of both "Ca. M. haematoparvum" and Mycoplasma haemocanis in dogs from Korea indicate that these organisms may be transmitted by vectors other than Rhipicephalus sanguineus because this tick species has rarely been found in Korea. This is the first nationwide survey for canine haemotropic mycoplasma infections in Korea. This study showed that the risk of exposure to major vector-borne diseases in dogs is quite high throughout all areas of South Korean Peninsula. Since achieving full elimination of many pathogens causing CVBDs from infected animals is often impossible even when they are clinically cured, dogs once exposed to CVBDs can remain as lifetime reservoirs of disease for both other animals and humans in the close vicinity, and should therefore be treated with preventative medications to minimise the risk of pathogen transmission by the competent vectors.

Recent weather extremes and impact agricultural production and vector-borne disease patterns

USDA-ARS?s Scientific Manuscript database

We document significant worldwide weather anomalies that affected agriculture and vector-borne disease outbreaks during the 2010-2012 period. We utilized 2000-2012 vegetation index and land surface temperature data from NASA’s satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) to ...

Predators indirectly control vector-borne disease: linking predator-prey and host-pathogen models.

PubMed

Moore, Sean M; Borer, Elizabeth T; Hosseini, Parviez R

2010-01-06

Pathogens transmitted by arthropod vectors are common in human populations, agricultural systems and natural communities. Transmission of these vector-borne pathogens depends on the population dynamics of the vector species as well as its interactions with other species within the community. In particular, predation may be sufficient to control pathogen prevalence indirectly via the vector. To examine the indirect effect of predators on vectored-pathogen dynamics, we developed a theoretical model that integrates predator-prey and host-pathogen theory. We used this model to determine whether predation can prevent pathogen persistence or alter the stability of host-pathogen dynamics. We found that, in the absence of predation, pathogen prevalence in the host increases with vector fecundity, whereas predation on the vector causes pathogen prevalence to decline, or even become extinct, with increasing vector fecundity. We also found that predation on a vector may drastically slow the initial spread of a pathogen. The predator can increase host abundance indirectly by reducing or eliminating infection in the host population. These results highlight the importance of studying interactions that, within the greater community, may alter our predictions when studying disease dynamics. From an applied perspective, these results also suggest situations where an introduced predator or the natural enemies of a vector may slow the rate of spread of an emerging vector-borne pathogen.

Sex-biased avian host use by arbovirus vectors.

PubMed

Burkett-Cadena, Nathan D; Bingham, Andrea M; Unnasch, Thomas R

2014-11-01

Prevalence of arthropod-borne parasites often differs drastically between host sexes. This sex-related disparity may be related to physiological (primarily hormonal) differences that facilitate or suppress replication of the pathogen in host tissues. Alternately, differences in pathogen prevalence between host sexes may be owing to differential exposure to infected vectors. Here, we report on the use of PCR-based assays recognizing bird sex chromosomes to investigate sex-related patterns of avian host use from field-collected female mosquitoes from Florida, USA. Mosquitoes took more bloodmeals from male birds (64.0% of 308 sexed samples) than female birds (36.0%), deviating significantly from a hypothetical 1:1 sex ratio. In addition, male-biased host use was consistent across mosquito species (Culex erraticus (64.4%); Culex nigripalpus (61.0%) and Culiseta melanura (64.9%)). Our findings support the hypothesis that sex-biased exposure to vector-borne pathogens contributes to disparities in parasite/pathogen prevalence between the sexes. While few studies have yet to investigate sex-biased host use by mosquitoes, the methods used here could be applied to a variety of mosquito-borne disease systems, including those that affect health of humans, domestic animals and wildlife. Understanding the mechanisms that drive sex-based disparities in host use may lead to novel strategies for interrupting pathogen/parasite transmission.

Urban Breeding Corvids as Disseminators of Ticks and Emerging Tick-Borne Pathogens.

PubMed

Sándor, Attila D; Kalmár, Zsuzsa; Matei, Ioana; Ionică, Angela Monica; Mărcuţan, Ioan-Daniel

2017-02-01

Crows (Corvidae) are common city dwellers worldwide and are increasingly important subjects of epidemiology studies. Although their importance as hosts and transmitters of a number of zoonotic parasites and pathogens is well known, there are no studies on their importance as tick hosts. After mosquitoes, ticks are the most important vectors of zoonotic pathogens, especially for those causing emerging zoonotic diseases. Pathogenic bacteria, especially Borrelia spp., Rickettsia spp., and Anaplasma spp., vectored by ticks, are the cause for most vector-borne diseases in Europe. Here we report on ticks and tick-borne pathogens harbored by urban breeding crows. A total of 36 birds (33.33%, n = 108) hosted ticks, with 91 individual ticks belonging to 6 species (Haemaphysalis concinna, Haemaphysalis parva, Haemaphysalis punctata, Hyalomma marginatum, Ixodes arboricola, and Ixodes ricinus). Rickettsia spp. DNA was found in 6.6% of ticks and 1.9% of bird tissues, whereas Anaplasma phagocytophilum was found in 5.9% of ticks and 0.9% of birds. Two rickettsial genospecies were located, Rickettsia helvetica and Rickettsia monacensis. This is the first study to determine such a diverse tick spectrum feeding on urban corvids, while highlighting their importance as tick hosts and raising concerns about their potential risk to human health.

The virulence–transmission trade-off in vector-borne plant viruses: a review of (non-)existing studies

PubMed Central

Froissart, R.; Doumayrou, J.; Vuillaume, F.; Alizon, S.; Michalakis, Y.

2010-01-01

The adaptive hypothesis invoked to explain why parasites harm their hosts is known as the trade-off hypothesis, which states that increased parasite transmission comes at the cost of shorter infection duration. This correlation arises because both transmission and disease-induced mortality (i.e. virulence) are increasing functions of parasite within-host density. There is, however, a glaring lack of empirical data to support this hypothesis. Here, we review empirical investigations reporting to what extent within-host viral accumulation determines the transmission rate and the virulence of vector-borne plant viruses. Studies suggest that the correlation between within-plant viral accumulation and transmission rate of natural isolates is positive. Unfortunately, results on the correlation between viral accumulation and virulence are very scarce. We found only very few appropriate studies testing such a correlation, themselves limited by the fact that they use symptoms as a proxy for virulence and are based on very few viral genotypes. Overall, the available evidence does not allow us to confirm or refute the existence of a transmission–virulence trade-off for vector-borne plant viruses. We discuss the type of data that should be collected and how theoretical models can help us refine testable predictions of virulence evolution. PMID:20478886

Babesia canis and other tick-borne infections in dogs in Central Poland.

PubMed

Welc-Faleciak, Renata; Rodo, Anna; Siński, Edward; Bajer, Anna

2009-12-23

Vector-borne infections constitute increasing health problem in dogs worldwide, including sled dogs, dramatically decreasing the fitness of working dogs and even leading to death. In the period 2006-2008 eighty-two blood samples were collected from eight sled dog kennels in Central Poland. The prevalence of four vector-borne infections (Babesia canis, Bartonella sp., Anaplasma/Ehrlichia and Borrelia burgdorferi) was estimated in 82 sled dogs using PCR and nested PCR for diagnosis and the same methods were used to identify the vector-borne pathogens in 26 dogs presenting at veterinary clinics with symptoms of vector-borne diseases. None of four studied vector-borne pathogens was detected in samples originating from veterinary clinics. Among the remaining 82 dogs B. canis infections were confirmed in three dogs undergoing treatment for babesiosis. The DNA of tick-borne pathogens was also found among 22 (27.8%) of the 79 apparently healthy dogs, including 20 cases of B. canis infection (25.3%), one case of B. burgdorferi s.l. infection and one case of Anaplasma phagocytophilum infection. No evidence of Bartonella spp. and Ehrlichia canis infections were found in this set of samples. Sequencing of a Babesia fragment of 18S rDNA amplified from acute (n=5) and asymptomatic (n=5) cases revealed that all isolates were identical to the Babesia canis canis sequence, originally isolated from Dermacentor reticulatus ticks in Poland. A range of factors was shown to affect the distribution of babesiosis in sled dogs. The data are also discussed in respect to the health risk factors generated by asymptomatic B. canis infections and the efficiency of chemoprophylaxis measures taken by sled dog owners.

Resurgent vector-borne diseases as a global health problem.

PubMed Central

Gubler, D. J.

1998-01-01

Vector-borne infectious diseases are emerging or resurging as a result of changes in public health policy, insecticide and drug resistance, shift in emphasis from prevention to emergency response, demographic and societal changes, and genetic changes in pathogens. Effective prevention strategies can reverse this trend. Research on vaccines, environmentally safe insecticides, alternative approaches to vector control, and training programs for health-care workers are needed. PMID:9716967

Vector-borne diseases and climate change: a European perspective

PubMed Central

Suk, Jonathan E

2017-01-01

Abstract Climate change has already impacted the transmission of a wide range of vector-borne diseases in Europe, and it will continue to do so in the coming decades. Climate change has been implicated in the observed shift of ticks to elevated altitudes and latitudes, notably including the Ixodes ricinus tick species that is a vector for Lyme borreliosis and tick-borne encephalitis. Climate change is also thought to have been a factor in the expansion of other important disease vectors in Europe: Aedes albopictus (the Asian tiger mosquito), which transmits diseases such as Zika, dengue and chikungunya, and Phlebotomus sandfly species, which transmits diseases including Leishmaniasis. In addition, highly elevated temperatures in the summer of 2010 have been associated with an epidemic of West Nile Fever in Southeast Europe and subsequent outbreaks have been linked to summer temperature anomalies. Future climate-sensitive health impacts are challenging to project quantitatively, in part due to the intricate interplay between non-climatic and climatic drivers, weather-sensitive pathogens and climate-change adaptation. Moreover, globalisation and international air travel contribute to pathogen and vector dispersion internationally. Nevertheless, monitoring forecasts of meteorological conditions can help detect epidemic precursors of vector-borne disease outbreaks and serve as early warning systems for risk reduction. PMID:29149298

Vector-borne diseases and climate change: a European perspective.

PubMed

Semenza, Jan C; Suk, Jonathan E

2018-02-01

Climate change has already impacted the transmission of a wide range of vector-borne diseases in Europe, and it will continue to do so in the coming decades. Climate change has been implicated in the observed shift of ticks to elevated altitudes and latitudes, notably including the Ixodes ricinus tick species that is a vector for Lyme borreliosis and tick-borne encephalitis. Climate change is also thought to have been a factor in the expansion of other important disease vectors in Europe: Aedes albopictus (the Asian tiger mosquito), which transmits diseases such as Zika, dengue and chikungunya, and Phlebotomus sandfly species, which transmits diseases including Leishmaniasis. In addition, highly elevated temperatures in the summer of 2010 have been associated with an epidemic of West Nile Fever in Southeast Europe and subsequent outbreaks have been linked to summer temperature anomalies. Future climate-sensitive health impacts are challenging to project quantitatively, in part due to the intricate interplay between non-climatic and climatic drivers, weather-sensitive pathogens and climate-change adaptation. Moreover, globalisation and international air travel contribute to pathogen and vector dispersion internationally. Nevertheless, monitoring forecasts of meteorological conditions can help detect epidemic precursors of vector-borne disease outbreaks and serve as early warning systems for risk reduction. © FEMS 2017.

Best Practices for Preventing Vector-Borne Diseases in Dogs and Humans.

PubMed

Dantas-Torres, Filipe; Otranto, Domenico

2016-01-01

Vector-borne diseases constitute a diversified group of illnesses, which are caused by a multitude of pathogens transmitted by arthropod vectors, such as mosquitoes, fleas, ticks, and sand flies. Proper management of these diseases is important from both human and veterinary medicine standpoints, given that many of these pathogens are transmissible to humans and dogs, which often live in close contact. In this review, we summarize the most important vector-borne diseases of dogs and humans and the best practices for their prevention. The control of these diseases would ultimately improve animal and human health and wellbeing, particularly in developing countries in the tropics, where the risk of these diseases is high and access to health care is poor. Copyright © 2015 Elsevier Ltd. All rights reserved.

Urbanization, land tenure security and vector-borne Chagas disease.

PubMed

Levy, Michael Z; Barbu, Corentin M; Castillo-Neyra, Ricardo; Quispe-Machaca, Victor R; Ancca-Juarez, Jenny; Escalante-Mejia, Patricia; Borrini-Mayori, Katty; Niemierko, Malwina; Mabud, Tarub S; Behrman, Jere R; Naquira-Velarde, Cesar

2014-08-22

Modern cities represent one of the fastest growing ecosystems on the planet. Urbanization occurs in stages; each stage characterized by a distinct habitat that may be more or less susceptible to the establishment of disease vector populations and the transmission of vector-borne pathogens. We performed longitudinal entomological and epidemiological surveys in households along a 1900 × 125 m transect of Arequipa, Peru, a major city of nearly one million inhabitants, in which the transmission of Trypanosoma cruzi, the aetiological agent of Chagas disease, by the insect vector Triatoma infestans, is an ongoing problem. The transect spans a cline of urban development from established communities to land invasions. We find that the vector is tracking the development of the city, and the parasite, in turn, is tracking the dispersal of the vector. New urbanizations are free of vector infestation for decades. T. cruzi transmission is very recent and concentrated in more established communities. The increase in land tenure security during the course of urbanization, if not accompanied by reasonable and enforceable zoning codes, initiates an influx of construction materials, people and animals that creates fertile conditions for epidemics of some vector-borne diseases. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Impact of climate variability on vector-borne disease transmission

USDA-ARS?s Scientific Manuscript database

We will discuss the impact of climate variability on vector borne diseases and demonstrate that global climate teleconnections can be used to anticipate and forecast, in the case of Rift Valley fever, epidemics and epizootics. In this context we will examine significant worldwide weather anomalies t...

78 FR 732 - Disease, Disability, and Injury Prevention and Control Special Emphasis Panel (SEP): Initial Review

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-04

... announced below concerns Identification, Surveillance, and Control of Vector-Borne and Zoonotic Infectious... in response to ``Identification, Surveillance, and Control of Vector- Borne and Zoonotic Infectious... DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention Disease...

Tick-borne pathogens and the vector potential of ticks in China.

PubMed

Yu, Zhijun; Wang, Hui; Wang, Tianhong; Sun, Wenying; Yang, Xiaolong; Liu, Jingze

2015-01-14

Ticks, as obligate blood-sucking ectoparasites, attack a broad range of vertebrates and transmit a great diversity of pathogenic microorganisms. They are considered second only to mosquitoes as vectors of human disease, and the most important vector of pathogens of domestic and wild animals. Of the 117 described species in the Chinese tick fauna, 60 are known to transmit one or more diseases: 36 species isolated within China and 24 species isolated outside China. Moreover, 38 of these species carry multiple pathogens, indicating the potentially vast role of these vectors in transmitting pathogens. Spotted fever is the most common tick-borne disease, and is carried by at least 27 tick species, with Lyme disease and human granulocytic anaplasmosis ranked as the second and third most widespread tick-borne diseases, carried by 13 and 10 species, respectively. Such knowledge provides us with clues for the identification of tick-associated pathogens and suggests ideas for the control of tick-borne diseases in China. However, the numbers of tick-associated pathogens and tick-borne diseases in China are probably underestimated because of the complex distribution and great diversity of tick species in this country.

Polarization analysis of a balloon-borne solar magnetograph

NASA Technical Reports Server (NTRS)

Reiley, Daniel J.; Chipman, Russell A.

1987-01-01

The main text of the report contains the particular results of our research which relate to the Experimental Vector Magnetograph (EXVM) and the Balloon-borne Vector Magnetograph (BVM). A brief overview of which elements in the EXVM and BVM that are relevant to this polarization analysis are presented. The possible meaning of the 10(exp -5) polarization specification for the BVM is discussed qualitatively. A recommendation of which polarization specification is most relevant for the BVM is provided. A diattenuation budget for the various surfaces in the BVM which will allow the polarization specification to be met is discussed. An explanation of the various coating specifications which are recommended is presented. Optical design of the EXVM and coating specification sheets for the BVM are presented. The appendices of this report contain the more general results of our research on the general topic of polarization aberrations. A general discussion of polarization aberration theory, in terms of the SAMEX solar magnetograph, and rigorous derivations for the Mueller matrices of optical systems are also presented in the appendices.

Host group formation decreases exposure to vector-borne disease: a field experiment in a 'hotspot' of West Nile virus transmission.

PubMed

Krebs, Bethany L; Anderson, Tavis K; Goldberg, Tony L; Hamer, Gabriel L; Kitron, Uriel D; Newman, Christina M; Ruiz, Marilyn O; Walker, Edward D; Brawn, Jeffrey D

2014-12-07

Animals can decrease their individual risk of predation by forming groups. The encounter-dilution hypothesis extends the potential benefits of gregariousness to biting insects and vector-borne disease by predicting that the per capita number of insect bites should decrease within larger host groups. Although vector-borne diseases are common and can exert strong selective pressures on hosts, there have been few tests of the encounter-dilution effect in natural systems. We conducted an experimental test of the encounter-dilution hypothesis using the American robin (Turdus migratorius), a common host species for the West Nile virus (WNV), a mosquito-borne pathogen. By using sentinel hosts (house sparrows, Passer domesticus) caged in naturally occurring communal roosts in the suburbs of Chicago, we assessed sentinel host risk of WNV exposure inside and outside of roosts. We also estimated per capita host exposure to infected vectors inside roosts and outside of roosts. Sentinel birds caged inside roosts seroconverted to WNV more slowly than those outside of roosts, suggesting that social groups decrease per capita exposure to infected mosquitoes. These results therefore support the encounter-dilution hypothesis in a vector-borne disease system. Our results suggest that disease-related selective pressures on sociality may depend on the mode of disease transmission. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Can Horton hear the whos? The importance of scale in mosquito-borne disease.

PubMed

Lord, C C; Alto, B W; Anderson, S L; Connelly, C R; Day, J F; Richards, S L; Smartt, C T; Tabachnick, W J

2014-03-01

The epidemiology of vector-borne pathogens is determined by mechanisms and interactions at different scales of biological organization, from individual-level cellular processes to community interactions between species and with the environment. Most research, however, focuses on one scale or level with little integration between scales or levels within scales. Understanding the interactions between levels and how they influence our perception of vector-borne pathogens is critical. Here two examples of biological scales (pathogen transmission and mosquito mortality) are presented to illustrate some of the issues of scale and to explore how processes on different levels may interact to influence mosquito-borne pathogen transmission cycles. Individual variation in survival, vector competence, and other traits affect population abundance, transmission potential, and community structure. Community structure affects interactions between individuals such as competition and predation, and thus influences the individual-level dynamics and transmission potential. Modeling is a valuable tool to assess interactions between scales and how processes at different levels can affect transmission dynamics. We expand an existing model to illustrate the types of studies needed, showing that individual-level variation in viral dose acquired or needed for infection can influence the number of infectious vectors. It is critical that interactions within and among biological scales and levels of biological organization are understood for greater understanding of pathogen transmission with the ultimate goal of improving control of vector-borne pathogens.

Dengue and climate change in Australia: predictions for the future should incorporate knowledge from the past.

PubMed

Russell, Richard C; Currie, Bart J; Lindsay, Michael D; Mackenzie, John S; Ritchie, Scott A; Whelan, Peter I

2009-03-02

Dengue transmission in Australia is currently restricted to Queensland, where the vector mosquito Aedes aegypti is established. Locally acquired infections have been reported only from urban areas in the north-east of the state, where the vector is most abundant. Considerable attention has been drawn to the potential impact of climate change on dengue distribution within Australia, with projections for substantial rises in incidence and distribution associated with increasing temperatures. However, historical data show that much of Australia has previously sustained both the vector mosquito and dengue viruses. Although current vector distribution is restricted to Queensland, the area inhabited by A. aegypti is larger than the disease-transmission areas, and is not restricted by temperature (or vector-control programs); thus, it is unlikely that rising temperatures alone will bring increased vector or virus distribution. Factors likely to be important to dengue and vector distribution in the future include increased dengue activity in Asian and Pacific nations that would raise rates of virus importation by travellers, importation of vectors via international ports to regions without A. aegypti, higher rates of domestic collection and storage of water that would provide habitat in urban areas, and growing human populations in northern Australia. Past and recent successful control initiatives in Australia lend support to the idea that well resourced and functioning surveillance programs, and effective public health intervention capabilities, are essential to counter threats from dengue and other mosquito-borne diseases. Models projecting future activity of dengue (or other vector-borne disease) with climate change should carefully consider the local historical and contemporary data on the ecology and distribution of the vector and local virus transmission.

Exploiting the potential of vector control for disease prevention.

PubMed

Townson, H; Nathan, M B; Zaim, M; Guillet, P; Manga, L; Bos, R; Kindhauser, M

2005-12-01

Although vector control has proven highly effective in preventing disease transmission, it is not being used to its full potential, thereby depriving disadvantaged populations of the benefits of well tried and tested methods. Following the discovery of synthetic residual insecticides in the 1940s, large-scale programmes succeeded in bringing many of the important vector-borne diseases under control. By the late 1960s, most vector-borne diseases--with the exception of malaria in Africa--were no longer considered to be of primary public health importance. The result was that control programmes lapsed, resources dwindled, and specialists in vector control disappeared from public health units. Within two decades, many important vector-borne diseases had re-emerged or spread to new areas. The time has come to restore vector control to its key role in the prevention of disease transmission, albeit with an increased emphasis on multiple measures, whether pesticide-based or involving environmental modification, and with a strengthened managerial and operational capacity. Integrated vector management provides a sound conceptual framework for deployment of cost-effective and sustainable methods of vector control. This approach allows for full consideration of the complex determinants of disease transmission, including local disease ecology, the role of human activity in increasing risks of disease transmission, and the socioeconomic conditions of affected communities.

Exploiting the potential of vector control for disease prevention.

PubMed Central

Townson, H.; Nathan, M. B.; Zaim, M.; Guillet, P.; Manga, L.; Bos, R.; Kindhauser, M.

2005-01-01

Although vector control has proven highly effective in preventing disease transmission, it is not being used to its full potential, thereby depriving disadvantaged populations of the benefits of well tried and tested methods. Following the discovery of synthetic residual insecticides in the 1940s, large-scale programmes succeeded in bringing many of the important vector-borne diseases under control. By the late 1960s, most vector-borne diseases--with the exception of malaria in Africa--were no longer considered to be of primary public health importance. The result was that control programmes lapsed, resources dwindled, and specialists in vector control disappeared from public health units. Within two decades, many important vector-borne diseases had re-emerged or spread to new areas. The time has come to restore vector control to its key role in the prevention of disease transmission, albeit with an increased emphasis on multiple measures, whether pesticide-based or involving environmental modification, and with a strengthened managerial and operational capacity. Integrated vector management provides a sound conceptual framework for deployment of cost-effective and sustainable methods of vector control. This approach allows for full consideration of the complex determinants of disease transmission, including local disease ecology, the role of human activity in increasing risks of disease transmission, and the socioeconomic conditions of affected communities. PMID:16462987

Characterization and Detection of Vector-borne Diseases in Endemic Transmission Areas

DTIC Science & Technology

2016-01-18

research in her laboratory and for introducing me to her many collaborators and friends all over the world. Thanks to all present and former members of...Luckhart at the University of California Davis for feedback on my dissertation research and manuscripts. Second, I would like to thank Dr. Jon...and mortality due to vector-borne diseases globally. The research described in this dissertation aims to improve detection methods for both the vector

The Effects of Climate Change and Globalization on Mosquito Vectors: Evidence from Jeju Island, South Korea on the Potential for Asian Tiger Mosquito (Aedes albopictus) Influxes and Survival from Vietnam Rather Than Japan

PubMed Central

Jeong, Ji Yeon; Yoo, Seung Jin; Koh, Young-Sang; Lee, Seogjae; Heo, Sang Taek; Seong, Seung-Yong; Lee, Keun Hwa

2013-01-01

Background Climate change affects the survival and transmission of arthropod vectors as well as the development rates of vector-borne pathogens. Increased international travel is also an important factor in the spread of vector-borne diseases (VBDs) such as dengue, West Nile, yellow fever, chikungunya, and malaria. Dengue is the most important vector-borne viral disease. An estimated 2.5 billion people are at risk of infection in the world and there are approximately 50 million dengue infections and an estimated 500,000 individuals are hospitalized with dengue haemorrhagic fever annually. The Asian tiger mosquito (Aedes albopictus) is one of the vectors of dengue virus, and populations already exist on Jeju Island, South Korea. Currently, colder winter temperatures kill off Asian tiger mosquito populations and there is no evidence of the mosquitos being vectors for the dengue virus in this location. However, dengue virus-bearing mosquito vectors can inflow to Jeju Island from endemic area such as Vietnam by increased international travel, and this mosquito vector's survival during colder winter months will likely occur due to the effects of climate change. Methods and Results In this section, we show the geographical distribution of medically important mosquito vectors such as Ae. albopictus, a vector of both dengue and chikungunya viruses; Culex pipiens, a vector of West Nile virus; and Anopheles sinensis, a vector of Plasmodium vivax, within Jeju Island, South Korea. We found a significant association between the mean temperature, amount of precipitation, and density of mosquitoes. The phylogenetic analyses show that an Ae. albopictus, collected in southern area of Jeju Island, was identical to specimens found in Ho Chi Minh, Vietnam, and not Nagasaki, Japan. Conclusion Our results suggest that mosquito vectors or virus-bearing vectors can transmit from epidemic regions of Southeast Asia to Jeju Island and can survive during colder winter months. Therefore, Jeju Island is no longer safe from vector borne diseases (VBDs) due to the effects of globalization and climate change, and we should immediately monitor regional climate change to identify newly emerging VBDs. PMID:23894312

The effects of climate change and globalization on mosquito vectors: evidence from Jeju Island, South Korea on the potential for Asian tiger mosquito (Aedes albopictus) influxes and survival from Vietnam rather than Japan.

PubMed

Lee, Su Hyun; Nam, Kwang Woo; Jeong, Ji Yeon; Yoo, Seung Jin; Koh, Young-Sang; Lee, Seogjae; Heo, Sang Taek; Seong, Seung-Yong; Lee, Keun Hwa

2013-01-01

Climate change affects the survival and transmission of arthropod vectors as well as the development rates of vector-borne pathogens. Increased international travel is also an important factor in the spread of vector-borne diseases (VBDs) such as dengue, West Nile, yellow fever, chikungunya, and malaria. Dengue is the most important vector-borne viral disease. An estimated 2.5 billion people are at risk of infection in the world and there are approximately 50 million dengue infections and an estimated 500,000 individuals are hospitalized with dengue haemorrhagic fever annually. The Asian tiger mosquito (Aedes albopictus) is one of the vectors of dengue virus, and populations already exist on Jeju Island, South Korea. Currently, colder winter temperatures kill off Asian tiger mosquito populations and there is no evidence of the mosquitos being vectors for the dengue virus in this location. However, dengue virus-bearing mosquito vectors can inflow to Jeju Island from endemic area such as Vietnam by increased international travel, and this mosquito vector's survival during colder winter months will likely occur due to the effects of climate change. In this section, we show the geographical distribution of medically important mosquito vectors such as Ae. albopictus, a vector of both dengue and chikungunya viruses; Culex pipiens, a vector of West Nile virus; and Anopheles sinensis, a vector of Plasmodium vivax, within Jeju Island, South Korea. We found a significant association between the mean temperature, amount of precipitation, and density of mosquitoes. The phylogenetic analyses show that an Ae. albopictus, collected in southern area of Jeju Island, was identical to specimens found in Ho Chi Minh, Vietnam, and not Nagasaki, Japan. Our results suggest that mosquito vectors or virus-bearing vectors can transmit from epidemic regions of Southeast Asia to Jeju Island and can survive during colder winter months. Therefore, Jeju Island is no longer safe from vector borne diseases (VBDs) due to the effects of globalization and climate change, and we should immediately monitor regional climate change to identify newly emerging VBDs.

Contributions of hydrology to Vesicular Stomatitis Virus emergence in the Western United States

USDA-ARS?s Scientific Manuscript database

Relationships between environmental variables associated with the spread of vector-borne pathogens, such as RNA viruses transmitted to humans and animals, remain poorly understood. Vesicular stomatitis (VS) is caused by a vector-borne, zoonotic RNA virus (VSV), and is the most common vesicular dise...

Occurrence of a Snail Borne Disease, Cercarial Dermatitis (Swimmer Itch) in Doon Valley (Uttarakhand), India

PubMed Central

JAUHARI, Rakesh Kumar; NONGTHOMBAM, Pemola Devi

2014-01-01

Abstract Background ‘Cercarial dermatitis’ also known as swimmers itch (Skin allergies) is caused by a trematode parasite, Schistosoma which has two hosts - an invertebrate (snail) and a vertebrate (livestock, human being). Although the availability of both vector snails and pathogens at the selected site the Doon Valley in northern India has already been confirmed but there was a hazy picture of the disease, whether it is due to entrance of cercariae or due to wild variety of grass (Parthenium hysterophorus). The present study is an attempt to provide a way forward towards the vector snails and snail borne diseases in the study area. Methods Snail sampling and identification was done by applying standard methods / using Keys & Catalogues. Associated parasites and cercariometry in snails has been worked out by cercarial shedding. Human involvement at zo-onotic level has been performed in collaboration with Health centers and socio- economic aspect of inhabitants of study area. Results The snail diversity encountered 19 species including the vector species such as Indoplanorbis exustus, Gyraulus convexiusculus, Melanoides tuberculata and Lymnaea acuminata. The cercarial diversity comprised Furcocercous, Monostome, Amphistome and liver fluke / Xiphidiocercaria. During the study (2009–2010), 0.173% was found with cercarial dermatitis among human population in the selected area. The symptoms of disease recorded were red spots and swellings on effected parts of skin. Frequent visits of livestock to the water body and presence of vector snails provides a clue in completing the life cycle of the parasite of the family Schistosomatidae. Conclusion Cercarial dermatitis has been considered a potential risk at those places where warm blooded and snail’s hosts share a link with aquatic bodies with particular emphasis to temperature and time of year. PMID:26060739

Imported Zika Virus in a European City: How to Prevent Local Transmission?

PubMed

Millet, Joan-Pau; Montalvo, Tomàs; Bueno-Marí, Ruben; Romero-Tamarit, Arancha; Prats-Uribe, Albert; Fernández, Lidia; Camprubí, Esteve; Del Baño, Lucía; Peracho, Victor; Figuerola, Jordi; Sulleiro, Elena; Martínez, Miguel J; Caylà, Joan A

2017-01-01

Background: On February 1st 2016 the WHO declared the Zika Virus (ZIKV) infection a worldwide public health emergency because of its rapid expansion and severe complications, such as Guillain-Barré Syndrome or microcephaly in newborn. The huge amount of people traveling to endemic areas and the presence of Aedes albopictus in Barcelona increase the risk of autochtonous transmission. The objective of this study was to describe the first ZIKV cases diagnosed in our city and to analyze the surveillance, prevention, and control measures implemented to avoid autochthonous transmission. Methods: An observational cross-sectional population-based study in Barcelona, Spain was performed.An analysis of the socio-demographic, epidemiological, clinical characteristics, and mosquito control activities of the ZIKV cases detected between January 1st and December 2016 was carried out using a specific ZIKV epidemiological survey of the Barcelona Public Health Agency. Results: A total of 118 notifications of possible ZIKV infections were received, and 44 corresponded to confirmed cases in Barcelona residents.Amongst these, the median age was 35 years and 57% were women. All cases were imported, 48% were Spanish-born and 52% foreign-born. Dominican Republic was the most visited country amongst foreign-born patients and Nicaragua amongst Spanish-born. The most frequent symptoms were exanthema, fever, and arthralgia. Among the 24 diagnosed women, 6 (25%) were pregnant. There was one case of microcephaly outside Barcelona city. Entomological inspections were done at the homes of 19 cases (43.2% of the total) and in 34 (77.3%) public spaces. Vector activity was found in one case of the 44 confirmed cases, and 134 surveillance and vector control were carried out associated to imported ZIKV cases. In all cases prevention measures were recommended to avoid mosquito bites on infected cases. Conclusion: Epidemiological and entomological surveillance are essential for the prevention of autochthonous transmission of arbovirosis that may have a great impact on Public Health.The good coordination between epidemiologists, entomologists, microbiologists, and clinicians is a priority in a touristic city with an intense relationship with endemic countries to minimize the risk of local transmission by competent vectors.

Imported Zika Virus in a European City: How to Prevent Local Transmission?

PubMed Central

Millet, Joan-Pau; Montalvo, Tomàs; Bueno-Marí, Ruben; Romero-Tamarit, Arancha; Prats-Uribe, Albert; Fernández, Lidia; Camprubí, Esteve; del Baño, Lucía; Peracho, Victor; Figuerola, Jordi; Sulleiro, Elena; Martínez, Miguel J.; Caylà, Joan A.; Álamo-Junquera, Dolores

2017-01-01

Background: On February 1st 2016 the WHO declared the Zika Virus (ZIKV) infection a worldwide public health emergency because of its rapid expansion and severe complications, such as Guillain-Barré Syndrome or microcephaly in newborn. The huge amount of people traveling to endemic areas and the presence of Aedes albopictus in Barcelona increase the risk of autochtonous transmission. The objective of this study was to describe the first ZIKV cases diagnosed in our city and to analyze the surveillance, prevention, and control measures implemented to avoid autochthonous transmission. Methods: An observational cross-sectional population-based study in Barcelona, Spain was performed.An analysis of the socio-demographic, epidemiological, clinical characteristics, and mosquito control activities of the ZIKV cases detected between January 1st and December 2016 was carried out using a specific ZIKV epidemiological survey of the Barcelona Public Health Agency. Results: A total of 118 notifications of possible ZIKV infections were received, and 44 corresponded to confirmed cases in Barcelona residents.Amongst these, the median age was 35 years and 57% were women. All cases were imported, 48% were Spanish-born and 52% foreign-born. Dominican Republic was the most visited country amongst foreign-born patients and Nicaragua amongst Spanish-born. The most frequent symptoms were exanthema, fever, and arthralgia. Among the 24 diagnosed women, 6 (25%) were pregnant. There was one case of microcephaly outside Barcelona city. Entomological inspections were done at the homes of 19 cases (43.2% of the total) and in 34 (77.3%) public spaces. Vector activity was found in one case of the 44 confirmed cases, and 134 surveillance and vector control were carried out associated to imported ZIKV cases. In all cases prevention measures were recommended to avoid mosquito bites on infected cases. Conclusion: Epidemiological and entomological surveillance are essential for the prevention of autochthonous transmission of arbovirosis that may have a great impact on Public Health.The good coordination between epidemiologists, entomologists, microbiologists, and clinicians is a priority in a touristic city with an intense relationship with endemic countries to minimize the risk of local transmission by competent vectors. PMID:28769893

The role of the ratio of vector and host densities in the evolution of transmission modes in vector-borne diseases. The example of sylvatic Trypanosoma cruzi.

PubMed

Pelosse, Perrine; Kribs-Zaleta, Christopher M

2012-11-07

Pathogens may use different routes of transmission to maximize their spread among host populations. Theoretical and empirical work conducted on directly transmitted diseases suggest that horizontal (i.e., through host contacts) and vertical (i.e., from mother to offspring) transmission modes trade off, on the ground that highly virulent pathogens, which produce larger parasite loads, are more efficiently transmitted horizontally, and that less virulent pathogens, which impair host fitness less significantly, are better transmitted vertically. Other factors than virulence such as host density could also select for different transmission modes, but they have barely been studied. In vector-borne diseases, pathogen transmission rate is strongly affected by host-vector relative densities and by processes of saturation in contacts between hosts and vectors. The parasite Trypanosoma cruzi which is transmitted by triatomine bugs to several vertebrate hosts is responsible for Chagas' disease in Latin America. It is also widespread in sylvatic cycles in the southeastern U.S. in which it typically induces no mortality costs to its customary hosts. Besides classical transmission via vector bites, alternative ways to generate infections in hosts such as vertical and oral transmission (via the consumption of vectors by hosts) have been reported in these cycles. The two major T. cruzi strains occurring in the U.S. seem to exhibit differential efficiencies at vertical and classical horizontal transmissions. We investigated whether the vector-host ratio affects the outcome of the competition between the two parasite strains using an epidemiological two-strain model considering all possible transmission routes for sylvatic T. cruzi. We were able to show that the vector-host ratio influences the evolution of transmission modes providing that oral transmission is included in the model as a possible transmission mode, that oral and classical transmissions saturate at different vector-host ratios and that the vector-host ratio is between the two saturation thresholds. Even if data on parasite strategies and demography of hosts and vectors in the field are crucially lacking to test to what extent the conditions needed for the vector-host ratio to influence evolution of transmission modes are plausible, our results open new perspectives for understanding the specialization of the two major T. cruzi strains occurring in the U.S. Our work also provides an original theoretical framework to investigate the evolution of alternative transmission modes in vector-borne diseases.

Models for the effects of host movement in vector-borne disease systems.

PubMed

Cosner, Chris

2015-12-01

Host and/or vector movement patterns have been shown to have significant effects in both empirical studies and mathematical models of vector-borne diseases. The processes of economic development and globalization seem likely to make host movement even more important in the future. This article is a brief survey of some of the approaches that have been used to study the effects of host movement in analytic mathematical models for vector-borne diseases. It describes the formulation and interpretation of various types of spatial models and describes a few of the conclusions that can be drawn from them. It is not intended to be comprehensive but rather to provide sufficient background material and references to the literature to serve as an entry point into this area of research for interested readers. Copyright © 2015 Elsevier Inc. All rights reserved.

Reducing vector-borne disease by empowering farmers in integrated vector management.

PubMed

van den Berg, Henk; von Hildebrand, Alexander; Ragunathan, Vaithilingam; Das, Pradeep K

2007-07-01

Irrigated agriculture exposes rural people to health risks associated with vector-borne diseases and pesticides used in agriculture and for public health protection. Most developing countries lack collaboration between the agricultural and health sectors to jointly address these problems. We present an evaluation of a project that uses the "farmer field school" method to teach farmers how to manage vector-borne diseases and how to improve rice yields. Teaching farmers about these two concepts together is known as "integrated pest and vector management". An intersectoral project targeting rice irrigation systems in Sri Lanka. Project partners developed a new curriculum for the field school that included a component on vector-borne diseases. Rice farmers in intervention villages who graduated from the field school took vector-control actions as well as improving environmental sanitation and their personal protection measures against disease transmission. They also reduced their use of agricultural pesticides, especially insecticides. The intervention motivated and enabled rural people to take part in vector-management activities and to reduce several environmental health risks. There is scope for expanding the curriculum to include information on the harmful effects of pesticides on human health and to address other public health concerns. Benefits of this approach for community-based health programmes have not yet been optimally assessed. Also, the institutional basis of the integrated management approach needs to be broadened so that people from a wider range of organizations take part. A monitoring and evaluation system needs to be established to measure the performance of integrated management initiatives.

Artificial Lighting as a Vector Attractant and Cause of Disease Diffusion

PubMed Central

Barghini, Alessandro; de Medeiros, Bruno A. S.

2010-01-01

Background Traditionally, epidemiologists have considered electrification to be a positive factor. In fact, electrification and plumbing are typical initiatives that represent the integration of an isolated population into modern society, ensuring the control of pathogens and promoting public health. Nonetheless, electrification is always accompanied by night lighting that attracts insect vectors and changes people’s behavior. Although this may lead to new modes of infection and increased transmission of insect-borne diseases, epidemiologists rarely consider the role of night lighting in their surveys. Objective We reviewed the epidemiological evidence concerning the role of lighting in the spread of vector-borne diseases to encourage other researchers to consider it in future studies. Discussion We present three infectious vector-borne diseases—Chagas, leishmaniasis, and malaria—and discuss evidence that suggests that the use of artificial lighting results in behavioral changes among human populations and changes in the prevalence of vector species and in the modes of transmission. Conclusion Despite a surprising lack of studies, existing evidence supports our hypothesis that artificial lighting leads to a higher risk of infection from vector-borne diseases. We believe that this is related not only to the simple attraction of traditional vectors to light sources but also to changes in the behavior of both humans and insects that result in new modes of disease transmission. Considering the ongoing expansion of night lighting in developing countries, additional research on this subject is urgently needed. PMID:20675268

Analysis of population structure and insecticide resistance in mosquitoes of the genus Culex, Anopheles and Aedes from different environments of Greece with a history of mosquito borne disease transmission.

PubMed

Fotakis, Emmanouil A; Chaskopoulou, Alexandra; Grigoraki, Linda; Tsiamantas, Alexandros; Kounadi, Stella; Georgiou, Loukas; Vontas, John

2017-10-01

Greece has been recently affected by several mosquito borne diseases with the West Nile Virus (WNV) outbreak in 2010 being one of the largest reported in Europe. Currently at the epicenter of an economic and refugee crisis and visited by over 16 million tourists a year the integrated management of diseases transmitted by mosquitoes is a public health and economic priority. Vector control programs rely mainly on insecticides, however data on insecticide resistance and the mosquito fauna is essential for successful applications. We determined the mosquito species composition and population dynamics in areas of increased vulnerability to vector borne disease transmission, as well as investigated the resistance status of major nuisance and disease vectors to insecticides. High mosquito densities were recorded in Thessaloniki and Evros, with Aedes caspius, a nuisance species, Culex pipiens, a known vector of WNV and Anopheles hyrcanus a potential vector of malaria being among the most prevalent species. Both vector species populations reached their peak in late summer. Aedes albopictus was recorded at high densities in Thessaloniki, but not in Evros. Notably, Cx. pipiens hybrids, which show an opportunistic biting behavior and are suspected to be involved in the transmission of the WNV, were recorded in considerable numbers in Thessaloniki and Attica. Culex pipiens and An. hyrcanus, but not Ae. caspius mosquitoes, showed moderate levels of resistance to deltamethrin. The presence of resistance in areas not exposed to vector control indicates that other factors could be selecting for resistance, i.e. pesticide applications for agriculture. Both L1014F and L101C kdr mutations were detected in Cx. pipiens populations. Anopheles hyrcanus resistance was not associated with mutations at the L1014 site. The Ace-1 mutations conferring insensitivity to organophosphates and carbamates were detected at low frequencies in all Cx. pipiens populations. Increased activity of P450s and esterases was found in Cx. pipiens individuals from Thessaloniki. Our study contributes evidence for sustainable and efficient vector control strategies and the prevention of disease outbreaks. Copyright © 2017 Elsevier B.V. All rights reserved.

Vector-virus interactions and transmission dynamics of West Nile virus.

PubMed

Ciota, Alexander T; Kramer, Laura D

2013-12-09

West Nile virus (WNV; Flavivirus; Flaviviridae) is the cause of the most widespread arthropod-borne viral disease in the world and the largest outbreak of neuroinvasive disease ever observed. Mosquito-borne outbreaks are influenced by intrinsic (e.g., vector and viral genetics, vector and host competence, vector life-history traits) and extrinsic (e.g., temperature, rainfall, human land use) factors that affect virus activity and mosquito biology in complex ways. The concept of vectorial capacity integrates these factors to address interactions of the virus with the arthropod host, leading to a clearer understanding of their complex interrelationships, how they affect transmission of vector-borne disease, and how they impact human health. Vertebrate factors including host competence, population dynamics, and immune status also affect transmission dynamics. The complexity of these interactions are further exacerbated by the fact that not only can divergent hosts differentially alter the virus, but the virus also can affect both vertebrate and invertebrate hosts in ways that significantly alter patterns of virus transmission. This chapter concentrates on selected components of the virus-vector-vertebrate interrelationship, focusing specifically on how interactions between vector, virus, and environment shape the patterns and intensity of WNV transmission.

Vector-Virus Interactions and Transmission Dynamics of West Nile Virus

PubMed Central

Ciota, Alexander T.; Kramer, Laura D.

2013-01-01

West Nile virus (WNV; Flavivirus; Flaviviridae) is the cause of the most widespread arthropod-borne viral disease in the world and the largest outbreak of neuroinvasive disease ever observed. Mosquito-borne outbreaks are influenced by intrinsic (e.g., vector and viral genetics, vector and host competence, vector life-history traits) and extrinsic (e.g., temperature, rainfall, human land use) factors that affect virus activity and mosquito biology in complex ways. The concept of vectorial capacity integrates these factors to address interactions of the virus with the arthropod host, leading to a clearer understanding of their complex interrelationships, how they affect transmission of vector-borne disease, and how they impact human health. Vertebrate factors including host competence, population dynamics, and immune status also affect transmission dynamics. The complexity of these interactions are further exacerbated by the fact that not only can divergent hosts differentially alter the virus, but the virus also can affect both vertebrate and invertebrate hosts in ways that significantly alter patterns of virus transmission. This chapter concentrates on selected components of the virus-vector-vertebrate interrelationship, focusing specifically on how interactions between vector, virus, and environment shape the patterns and intensity of WNV transmission. PMID:24351794

Bayesian data assimilation provides rapid decision support for vector-borne diseases

PubMed Central

Jewell, Chris P.; Brown, Richard G.

2015-01-01

Predicting the spread of vector-borne diseases in response to incursions requires knowledge of both host and vector demographics in advance of an outbreak. Although host population data are typically available, for novel disease introductions there is a high chance of the pathogen using a vector for which data are unavailable. This presents a barrier to estimating the parameters of dynamical models representing host–vector–pathogen interaction, and hence limits their ability to provide quantitative risk forecasts. The Theileria orientalis (Ikeda) outbreak in New Zealand cattle demonstrates this problem: even though the vector has received extensive laboratory study, a high degree of uncertainty persists over its national demographic distribution. Addressing this, we develop a Bayesian data assimilation approach whereby indirect observations of vector activity inform a seasonal spatio-temporal risk surface within a stochastic epidemic model. We provide quantitative predictions for the future spread of the epidemic, quantifying uncertainty in the model parameters, case infection times and the disease status of undetected infections. Importantly, we demonstrate how our model learns sequentially as the epidemic unfolds and provide evidence for changing epidemic dynamics through time. Our approach therefore provides a significant advance in rapid decision support for novel vector-borne disease outbreaks. PMID:26136225

Climate Change, Public Health, and Decision Support: The New Threat of Vector-borne Disease

NASA Astrophysics Data System (ADS)

Grant, F.; Kumar, S.

2011-12-01

Climate change and vector-borne diseases constitute a massive threat to human development. It will not be enough to cut emissions of greenhouse gases-the tide of the future has already been established. Climate change and vector-borne diseases are already undermining the world's efforts to reduce extreme poverty. It is in the best interests of the world leaders to think in terms of concerted global actions, but adaptation and mitigation must be accomplished within the context of local community conditions, resources, and needs. Failure to act will continue to consign developed countries to completely avoidable health risks and significant expense. Failure to act will also reduce poorest of the world's population-some 2.6 billion people-to a future of diminished opportunity. Northrop Grumman has taken significant steps forward to develop the tools needed to assess climate change impacts on public health, collect relevant data for decision making, model projections at regional and local levels; and, deliver information and knowledge to local and regional stakeholders. Supporting these tools is an advanced enterprise architecture consisting of high performance computing, GIS visualization, and standards-based architecture. To address current deficiencies in local planning and decision making with respect to regional climate change and its effect on human health, our research is focused on performing a dynamical downscaling with the Weather Research and Forecasting (WRF) model to develop decision aids that translate the regional climate data into actionable information for users. For the present climate WRF was forced with the Max Planck Institute European Center/Hamburg Model version 5 (ECHAM5) General Circulation Model 20th century simulation. For the 21th century climate, we used an ECHAM5 simulation with the Special Report on Emissions (SRES) A1B emissions scenario. WRF was run in nested mode at spatial resolution of 108 km, 36 km and 12 km and 28 vertical levels. This model was examined relative to two mosquito vectors, both competent carriers of dengue fever, a viral, vector-borne disease. Models which incorporate public health considerations can enable decision makers to take proactive steps to mitigate the impacts and adapt to the changing environmental conditions. In this paper we provide a snapshot of our climate initiative and some examples relative to our public health practice work in vector-borne diseases to illustrate how integrated decision support could be of assistance to regional and local communities worldwide.

Clinical and molecular investigation of a canine distemper outbreak and vector-borne infections in a group of rescue dogs imported from Hungary to Switzerland.

PubMed

Willi, Barbara; Spiri, Andrea M; Meli, Marina L; Grimm, Felix; Beatrice, Laura; Riond, Barbara; Bley, Tim; Jordi, Rolf; Dennler, Matthias; Hofmann-Lehmann, Regina

2015-07-16

Canine distemper virus (CDV) is a major pathogen of dogs and wild carnivores worldwide. In Switzerland, distemper in domestic dogs is rarely reported. In recent years, the import of dogs from Eastern Europe to Switzerland has steadily increased. In the present study, we describe a distemper outbreak in 15 rescue dogs that were imported from Hungary to Switzerland by an animal welfare organisation. The data on vaccination and medical history were recorded (14 dogs), and the samples were collected to investigate CDV and vector-borne infections (13 dogs) and canine parvovirus infection (12 dogs). The dogs were monitored for six months. One dog was euthanised directly after import. Thirteen dogs showed clinical signs after arrival, i.e., diarrhoea (57 %), coughing (43 %) and nasal and/or ocular discharge (21 %); radiographic findings that were compatible with bronchopneumonia were present in four dogs. CDV infection was diagnosed in 11 dogs (85 %); 10 dogs (91 %) tested PCR-positive in conjunctival swabs. Vector-borne infections (Babesia spp., Leishmania infantum, Dirofilaria immitis) were found in 4 dogs (31 %). Three dogs were hospitalized, and six dogs received ambulatory therapy for up to two months until recovery. None of the dogs developed neurological disease. CDV shedding was detected for a period of up to four months. Because dogs were put under strict quarantine until CDV shedding ceased, CDV did not spread to any other dogs. The CDV isolates showed 99 % sequence identity in the HA gene among each other and belonged to the Arctic-like lineage of CDV. The present study highlights the imminent risks of spreading contagious viral and vector-borne infections through the non-selective import of sick dogs and dogs with incomplete vaccination from Eastern Europe. CDV shedding was detected for several months after the cessation of clinical signs, which emphasised the roles of asymptomatic carriers in CDV epidemiology. A long-term follow-up using sensitive PCR and strict quarantine measures is of upmost importance in preventing the spread of infection. Dog owners and animal welfare organisations should be educated regarding the importance of complete vaccinations and the impact of dog imports on the spread of viral and vector-borne pathogens.

Does the arthropod microbiota impact the establishment of vector-borne diseases in mammalian hosts?

PubMed

Finney, Constance A M; Kamhawi, Shaden; Wasmuth, James D

2015-04-01

The impact of the microbiota on the immune status of its host is a source of intense research and publicity. In comparison, the effect of arthropod microbiota on vector-borne infectious diseases has received little attention. A better understanding of the vector microbiota in relation to mammalian host immune responses is vital, as it can lead to strategies that affect transmission and improve vaccine design in a field of research where few vaccines exist and effective treatment is rare. Recent demonstrations of how microbiota decrease pathogen development in arthropods, and thus alter vector permissiveness to vector-borne diseases (VBDs), have led to renewed interest. However, hypotheses on the interactions between the arthropod-derived microbiota and the mammalian hosts have yet to be addressed. Advances in DNA sequencing technology, increased yield and falling costs, mean that these studies are now feasible for many microbiologists and entomologists. Here, we distill current knowledge and put forward key questions and experimental designs to shed light on this burgeoning research topic.

Does the Arthropod Microbiota Impact the Establishment of Vector-Borne Diseases in Mammalian Hosts?

PubMed Central

Finney, Constance A. M.; Kamhawi, Shaden; Wasmuth, James D.

2015-01-01

The impact of the microbiota on the immune status of its host is a source of intense research and publicity. In comparison, the effect of arthropod microbiota on vector-borne infectious diseases has received little attention. A better understanding of the vector microbiota in relation to mammalian host immune responses is vital, as it can lead to strategies that affect transmission and improve vaccine design in a field of research where few vaccines exist and effective treatment is rare. Recent demonstrations of how microbiota decrease pathogen development in arthropods, and thus alter vector permissiveness to vector-borne diseases (VBDs), have led to renewed interest. However, hypotheses on the interactions between the arthropod-derived microbiota and the mammalian hosts have yet to be addressed. Advances in DNA sequencing technology, increased yield and falling costs, mean that these studies are now feasible for many microbiologists and entomologists. Here, we distill current knowledge and put forward key questions and experimental designs to shed light on this burgeoning research topic. PMID:25856431

Surveillance of vector-borne pathogens under imperfect detection: lessons from Chagas disease risk (mis)measurement.

PubMed

Minuzzi-Souza, Thaís Tâmara Castro; Nitz, Nadjar; Cuba, César Augusto Cuba; Hagström, Luciana; Hecht, Mariana Machado; Santana, Camila; Ribeiro, Marcelle; Vital, Tamires Emanuele; Santalucia, Marcelo; Knox, Monique; Obara, Marcos Takashi; Abad-Franch, Fernando; Gurgel-Gonçalves, Rodrigo

2018-01-09

Vector-borne pathogens threaten human health worldwide. Despite their critical role in disease prevention, routine surveillance systems often rely on low-complexity pathogen detection tests of uncertain accuracy. In Chagas disease surveillance, optical microscopy (OM) is routinely used for detecting Trypanosoma cruzi in its vectors. Here, we use replicate T. cruzi detection data and hierarchical site-occupancy models to assess the reliability of OM-based T. cruzi surveillance while explicitly accounting for false-negative and false-positive results. We investigated 841 triatomines with OM slides (1194 fresh, 1192 Giemsa-stained) plus conventional (cPCR, 841 assays) and quantitative PCR (qPCR, 1682 assays). Detections were considered unambiguous only when parasitologists unmistakably identified T. cruzi in Giemsa-stained slides. qPCR was >99% sensitive and specific, whereas cPCR was ~100% specific but only ~55% sensitive. In routine surveillance, examination of a single OM slide per vector missed ~50-75% of infections and wrongly scored as infected ~7% of the bugs. qPCR-based and model-based infection frequency estimates were nearly three times higher, on average, than OM-based indices. We conclude that the risk of vector-borne Chagas disease may be substantially higher than routine surveillance data suggest. The hierarchical modelling approach we illustrate can help enhance vector-borne disease surveillance systems when pathogen detection is imperfect.

Vectors as Epidemiological Sentinels: Patterns of Within-Tick Borrelia burgdorferi Diversity

PubMed Central

Walter, Katharine S.; Carpi, Giovanna; Evans, Benjamin R.; Caccone, Adalgisa; Diuk-Wasser, Maria A.

2016-01-01

Hosts including humans, other vertebrates, and arthropods, are frequently infected with heterogeneous populations of pathogens. Within-host pathogen diversity has major implications for human health, epidemiology, and pathogen evolution. However, pathogen diversity within-hosts is difficult to characterize and little is known about the levels and sources of within-host diversity maintained in natural populations of disease vectors. Here, we examine genomic variation of the Lyme disease bacteria, Borrelia burgdorferi (Bb), in 98 individual field-collected tick vectors as a model for study of within-host processes. Deep population sequencing reveals extensive and previously undocumented levels of Bb variation: the majority (~70%) of ticks harbor mixed strain infections, which we define as levels Bb diversity pre-existing in a diverse inoculum. Within-tick diversity is thus a sample of the variation present within vertebrate hosts. Within individual ticks, we detect signatures of positive selection. Genes most commonly under positive selection across ticks include those involved in dissemination in vertebrate hosts and evasion of the vertebrate immune complement. By focusing on tick-borne Bb, we show that vectors can serve as epidemiological and evolutionary sentinels: within-vector pathogen diversity can be a useful and unbiased way to survey circulating pathogen diversity and identify evolutionary processes occurring in natural transmission cycles. PMID:27414806

Non-essential viral proteins of orbiviruses are essential for vector-borne spread by midges

USDA-ARS?s Scientific Manuscript database

Members of the Reoviridae family are non-enveloped multi-layered viruses with a double stranded RNA genome consisting of 9-12 genome segments. The Orbivirus genus contains vector borne virus species with 10 genome segments such as bluetongue virus (BTV) with about 30 serotypes, and African horse sic...

Molecular entomology: analyzing tiny molecules to answer big questions about disease vectors and their biology

USDA-ARS?s Scientific Manuscript database

The entomologists at the Arthropod-Borne Animal Diseases Research Unit at USDA-Agricultural Research Service are tasked with protecting the nation’s livestock from domestic, foreign and emerging vector-borne diseases. To accomplish this task, a vast array of molecular techniques are being used in pr...

Molecular evidence of vector-borne pathogens in dogs and cats and their ectoparasites in Algiers, Algeria.

PubMed

Bessas, Amina; Leulmi, Hamza; Bitam, Idir; Zaidi, Sara; Ait-Oudhia, Khatima; Raoult, Didier; Parola, Philippe

2016-04-01

In Algeria, only limited information is currently available on the prevalence of emergent canine and feline vector-borne diseases. The aim of the present work was to detect by qPCR vector-associated bacteria in stray dogs and cats and their ectoparasites from Algiers. 18/117 (15.38%) dogs and 2/107 (1.87%) cats were positive for at least one vector-borne agent. Coxiella burnetii and Bartonella henselae were identified in 1/117 (0.85%) dog individually. Ehrlichia canis DNA was detected in 17/117 (14.52%) dogs. 1/107 (0.93%) cat was positive to C. burnetii and another 1/107 (0.93%) to B. henselae. DNA of Rickettsia massiliae, Rickettsia conorii and E. canis was detected in Rhipicephalus sanguineus. Cat fleas were infected with Rickettsia felis, B. henselae and Bartonella clarridgeiae. B. vinsonii subsp. berkhoffii was identified in Xenopsylla cheopis collected from dogs. The findings of this study indicate that dogs and cats from Algeria are exposed to multiple tick and flea-borne pathogens. Copyright © 2016 Elsevier Ltd. All rights reserved.

Vectors of rickettsiae in Africa.

PubMed

Bitam, Idir

2012-12-01

Vector-borne diseases are caused by parasites, bacteria, or viruses transmitted by the bites of hematophagous arthropods. In Africa, there has been a recent emergence of new diseases and the re-emergence of existing diseases, usually with changes in disease epidemiology (e.g., geographical distribution, prevalence, and pathogenicity). In Africa, rickettsioses are recognized as important emerging vector-borne infections in humans. Rickettsial diseases are transmitted by different types of arthropods, ticks, fleas, lice, and mites. This review will examine the roles of these different arthropod vectors and their geographical distributions. Copyright © 2012 Elsevier GmbH. All rights reserved.

Bayesian data assimilation provides rapid decision support for vector-borne diseases.

PubMed

Jewell, Chris P; Brown, Richard G

2015-07-06

Predicting the spread of vector-borne diseases in response to incursions requires knowledge of both host and vector demographics in advance of an outbreak. Although host population data are typically available, for novel disease introductions there is a high chance of the pathogen using a vector for which data are unavailable. This presents a barrier to estimating the parameters of dynamical models representing host-vector-pathogen interaction, and hence limits their ability to provide quantitative risk forecasts. The Theileria orientalis (Ikeda) outbreak in New Zealand cattle demonstrates this problem: even though the vector has received extensive laboratory study, a high degree of uncertainty persists over its national demographic distribution. Addressing this, we develop a Bayesian data assimilation approach whereby indirect observations of vector activity inform a seasonal spatio-temporal risk surface within a stochastic epidemic model. We provide quantitative predictions for the future spread of the epidemic, quantifying uncertainty in the model parameters, case infection times and the disease status of undetected infections. Importantly, we demonstrate how our model learns sequentially as the epidemic unfolds and provide evidence for changing epidemic dynamics through time. Our approach therefore provides a significant advance in rapid decision support for novel vector-borne disease outbreaks. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Constancy and diversity in the flavivirus fusion peptide.

PubMed

Seligman, Stephen J

2008-02-14

Flaviviruses include the mosquito-borne dengue, Japanese encephalitis, yellow fever and West Nile and the tick-borne encephalitis viruses. They are responsible for considerable world-wide morbidity and mortality. Viral entry is mediated by a conserved fusion peptide containing 16 amino acids located in domain II of the envelope protein E. Highly orchestrated conformational changes initiated by exposure to acidic pH accompany the fusion process and are important factors limiting amino acid changes in the fusion peptide that still permit fusion with host cell membranes in both arthropod and vertebrate hosts. The cell-fusing related agents, growing only in mosquitoes or insect cell lines, possess a different homologous peptide. Analysis of 46 named flaviviruses deposited in the Entrez Nucleotides database extended the constancy in the canonical fusion peptide sequences of mosquito-borne, tick-borne and viruses with no known vector to include more recently-sequenced viruses. The mosquito-borne signature amino acid, G104, was also found in flaviviruses with no known vector and with the cell-fusion related viruses. Despite the constancy in the canonical sequences in pathogenic flaviviruses, mutations were surprisingly frequent with a 27% prevalence of nonsynonymous mutations in yellow fever virus fusion peptide sequences, and 0 to 7.4% prevalence in the others. Six of seven yellow fever patients whose virus had fusion peptide mutations died. In the cell-fusing related agents, not enough sequences have been deposited to estimate reliably the prevalence of fusion peptide mutations. However, the canonical sequences homologous to the fusion peptide and the pattern of disulfide linkages in protein E differed significantly from the other flaviviruses. The constancy of the canonical fusion peptide sequences in the arthropod-borne flaviviruses contrasts with the high prevalence of mutations in most individual viruses. The discrepancy may be the result of a survival advantage accompanying sequence diversity (quasispecies) involving the fusion peptide. Limited clinical data with yellow fever virus suggest that the presence of fusion peptide mutants is not associated with a decreased case fatality rate. The cell-fusing related agents may have substantial differences from other flaviviruses in their mechanism of viral entry into the host cell.

Internet-based biosurveillance methods for vector-borne diseases: Are they novel public health tools or just novelties?

PubMed

Pollett, Simon; Althouse, Benjamin M; Forshey, Brett; Rutherford, George W; Jarman, Richard G

2017-11-01

Internet-based surveillance methods for vector-borne diseases (VBDs) using "big data" sources such as Google, Twitter, and internet newswire scraping have recently been developed, yet reviews on such "digital disease detection" methods have focused on respiratory pathogens, particularly in high-income regions. Here, we present a narrative review of the literature that has examined the performance of internet-based biosurveillance for diseases caused by vector-borne viruses, parasites, and other pathogens, including Zika, dengue, other arthropod-borne viruses, malaria, leishmaniasis, and Lyme disease across a range of settings, including low- and middle-income countries. The fundamental features, advantages, and drawbacks of each internet big data source are presented for those with varying familiarity of "digital epidemiology." We conclude with some of the challenges and future directions in using internet-based biosurveillance for the surveillance and control of VBD.

Internet-based biosurveillance methods for vector-borne diseases: Are they novel public health tools or just novelties?

PubMed Central

Pollett, Simon; Althouse, Benjamin M.; Forshey, Brett; Rutherford, George W.; Jarman, Richard G.

2017-01-01

Internet-based surveillance methods for vector-borne diseases (VBDs) using “big data” sources such as Google, Twitter, and internet newswire scraping have recently been developed, yet reviews on such “digital disease detection” methods have focused on respiratory pathogens, particularly in high-income regions. Here, we present a narrative review of the literature that has examined the performance of internet-based biosurveillance for diseases caused by vector-borne viruses, parasites, and other pathogens, including Zika, dengue, other arthropod-borne viruses, malaria, leishmaniasis, and Lyme disease across a range of settings, including low- and middle-income countries. The fundamental features, advantages, and drawbacks of each internet big data source are presented for those with varying familiarity of “digital epidemiology.” We conclude with some of the challenges and future directions in using internet-based biosurveillance for the surveillance and control of VBD. PMID:29190281

Remote Sensing the Patterns of Vector-borne Disease in El Nino and non-El Nino Years

NASA Technical Reports Server (NTRS)

Wood, B. L.; Chang, J.; Lobitz, B.; Beck, L.; DAntoni, Hector (Technical Monitor)

1997-01-01

The relationship between El Nino and non-El Nino and the patterns of vector-borne disease can be viewed at a variety of spatial and temporal scales. At one extreme are long term predictions of changing precipitation and temperature patterns at continental and global scales. At the opposite extreme are the local or site specific ecological changes associated with the long term events. In order to understand and address the human health consequences of El Nino events, especially the patterns of vector-borne diseases, it is necessary to combine both scales of observation. At a local or regional scale the patterns of vector-borne diseases are determined by temperature, precipitation, and habitat availability. These factors, as well as disease incidence can be altered by El Nino events. Remote sensing data such as that acquired by the NOAA AVHRR and Landsat TM sensors can be used to characterize and monitor changing ecological conditions and therefore predict vector-borne disease patterns. The authors present the results of preliminary work on the analysis of historical AVHRR and TM data acquired during El Nino and nonfatal Nino years to characterize ecological conditions in Peru on a monthly basis. This information will then be combined with disease data to determine the relationship between changes in ecological conditions and disease incidence. Our goal is to produce a sequence of remotely sensed images which can be used to show the ecological and disease patterns associated with long term El Nino events and predictions.

Legal aspects of public health: difficulties in controlling vector-borne and zoonotic diseases in Brazil.

PubMed

Mendes, Marcílio S; de Moraes, Josué

2014-11-01

In recent years, vector-borne and zoonotic diseases have become a major challenge for public health. Dengue fever and leptospirosis are the most important communicable diseases in Brazil based on their prevalence and the healthy life years lost from disability. The primary strategy for preventing human exposure to these diseases is effective insect and rodent control in and around the home. However, health authorities have difficulties in controlling vector-borne and zoonotic diseases because residents often refuse access to their homes. This study discusses aspects related to the activities performed by Brazilian health authorities to combat vector-borne and zoonotic diseases, particularly difficulties in relation to the legal aspect, which often impede the quick and effective actions of these professionals. How might it be possible to reconcile the need to preserve public health and the rule on the inviolability of the home, especially in the case of abandoned properties or illegal residents and the refusal of residents to allow the health authority access? Do residents have the right to hinder the performance of health workers even in the face of a significant and visible focus of disease transmission? This paper argues that a comprehensive legal plan aimed at the control of invasive vector-borne and zoonotic diseases including synanthropic animals of public health importance should be considered. In addition, this paper aims to bridge the gap between lawyers and public health professionals and to facilitate communication between them. Copyright © 2014 Elsevier B.V. All rights reserved.

Impact of drought on vector-borne diseases--how does one manage the risk?

PubMed

Brown, L; Medlock, J; Murray, V

2014-01-01

This article aimed to review all literature on drought and vector-borne disease to enable an assessment of the possible impact of drought on the changing risk of vector-borne diseases in the UK. A systematic literature review was performed. Using a search strategy developed from a combination of terms for drought and selected outcomes, the authors systematically reviewed all available literature from 1990 to 2012 on the impact of drought on vector-borne diseases. The following databases were searched: PubMed, Web of Science, and EMBASE. After reviewing the abstracts, 38 articles were found to fit the inclusion and exclusion criteria. Evidence found drought followed by re-wetting can have a substantial effect on water table levels, vegetation, and aquatic predators; all factors which influence mosquito populations. Several studies found an association between a drought during the previous year and West Nile virus incidence. Urban mosquito vectors of dengue virus and chikungunya virus are adaptable by nature and are able to exploit a multitude of additional aquatic habitats created as a response to drought (i.e. water storage containers). Tick populations are likely to be negatively affected by drought as they are dependent upon high levels of humidity and soil moisture. Further research is needed to identify public health interventions and environmental control measures for an invasive mosquito problem or arthropod-borne disease outbreak in the UK. Copyright © 2013 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Molecular Detection of Rickettsia amblyommii in Amblyomma americanum Parasitizing Humans

DTIC Science & Technology

2010-01-01

Rocky Mountain spotted fever [RMSF...diseases in North Carolina: is "Rickettsia amblyommii" a possible cause of rickettsiosis reported as Rocky Mountain spotted fever ? Vector Borne Zoonot...HN, et al. Rickettsia parkeri rickettsiosis and its clinical distinction from Rocky Mountain spotted fever . Clin Infect Dis 2008; 47:1188-

75 FR 154 - Agency Forms Undergoing Paperwork Reduction Act Review

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-04

.... Proposed Project Malaria Pre-travel Advice: Knowledge and Practices Among US Healthcare Providers Whose Patients Develop Malaria--New--National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED... 1505 cases of malaria reported in the U.S. and its territories. Except for one transfusion-related case...

Mosquito vector diversity across habitats in central Thailand endemic for dengue and other arthropod-borne diseases.

PubMed

Thongsripong, Panpim; Green, Amy; Kittayapong, Pattamaporn; Kapan, Durrell; Wilcox, Bruce; Bennett, Shannon

2013-01-01

Recent years have seen the greatest ecological disturbances of our times, with global human expansion, species and habitat loss, climate change, and the emergence of new and previously-known infectious diseases. Biodiversity loss affects infectious disease risk by disrupting normal relationships between hosts and pathogens. Mosquito-borne pathogens respond to changing dynamics on multiple transmission levels and appear to increase in disturbed systems, yet current knowledge of mosquito diversity and the relative abundance of vectors as a function of habitat change is limited. We characterize mosquito communities across habitats with differing levels of anthropogenic ecological disturbance in central Thailand. During the 2008 rainy season, adult mosquito collections from 24 sites, representing 6 habitat types ranging from forest to urban, yielded 62,126 intact female mosquitoes (83,325 total mosquitoes) that were assigned to 109 taxa. Female mosquito abundance was highest in rice fields and lowest in forests. Diversity indices and rarefied species richness estimates indicate the mosquito fauna was more diverse in rural and less diverse in rice field habitats, while extrapolated estimates of true richness (Chao1 and ACE) indicated higher diversity in the forest and fragmented forest habitats and lower diversity in the urban. Culex sp. (Vishnui subgroup) was the most common taxon found overall and the most frequent in fragmented forest, rice field, rural, and suburban habitats. The distributions of species of medical importance differed significantly across habitat types and were always lowest in the intact, forest habitat. The relative abundance of key vector species, Aedes aegypti and Culex quinquefasciatus, was negatively correlated with diversity, suggesting that direct species interactions and/or habitat-mediated factors differentially affecting invasive disease vectors may be important mechanisms linking biodiversity loss to human health. Our results are an important first step for understanding the dynamics of mosquito vector distributions under changing environmental features across landscapes of Thailand.

Mosquito Vector Diversity across Habitats in Central Thailand Endemic for Dengue and Other Arthropod-Borne Diseases

PubMed Central

Thongsripong, Panpim; Green, Amy; Kittayapong, Pattamaporn; Kapan, Durrell; Wilcox, Bruce; Bennett, Shannon

2013-01-01

Recent years have seen the greatest ecological disturbances of our times, with global human expansion, species and habitat loss, climate change, and the emergence of new and previously-known infectious diseases. Biodiversity loss affects infectious disease risk by disrupting normal relationships between hosts and pathogens. Mosquito-borne pathogens respond to changing dynamics on multiple transmission levels and appear to increase in disturbed systems, yet current knowledge of mosquito diversity and the relative abundance of vectors as a function of habitat change is limited. We characterize mosquito communities across habitats with differing levels of anthropogenic ecological disturbance in central Thailand. During the 2008 rainy season, adult mosquito collections from 24 sites, representing 6 habitat types ranging from forest to urban, yielded 62,126 intact female mosquitoes (83,325 total mosquitoes) that were assigned to 109 taxa. Female mosquito abundance was highest in rice fields and lowest in forests. Diversity indices and rarefied species richness estimates indicate the mosquito fauna was more diverse in rural and less diverse in rice field habitats, while extrapolated estimates of true richness (Chao1 and ACE) indicated higher diversity in the forest and fragmented forest habitats and lower diversity in the urban. Culex sp. (Vishnui subgroup) was the most common taxon found overall and the most frequent in fragmented forest, rice field, rural, and suburban habitats. The distributions of species of medical importance differed significantly across habitat types and were always lowest in the intact, forest habitat. The relative abundance of key vector species, Aedes aegypti and Culex quinquefasciatus, was negatively correlated with diversity, suggesting that direct species interactions and/or habitat-mediated factors differentially affecting invasive disease vectors may be important mechanisms linking biodiversity loss to human health. Our results are an important first step for understanding the dynamics of mosquito vector distributions under changing environmental features across landscapes of Thailand. PMID:24205420

Zika Virus in Salivary Glands of Five Different Species of Wild-Caught Mosquitoes from Mexico.

PubMed

Elizondo-Quiroga, Darwin; Medina-Sánchez, Aarón; Sánchez-González, Jorge M; Eckert, Kristen Allison; Villalobos-Sánchez, Erendira; Navarro-Zúñiga, Antonio Rigoberto; Sánchez-Tejeda, Gustavo; Correa-Morales, Fabián; González-Acosta, Cassandra; Arias, Carlos F; López, Susana; Del Ángel, Rosa María; Pando-Robles, Victoria; Elizondo-Quiroga, Armando E

2018-01-16

Zika virus (ZIKV) is a mosquito-borne pathogen, and Aedes aegypti has been identified as the main vector of the disease. Other mosquito species in the Aedes and Culex genera have been suggested to have the potential for being competent vectors based on experimental exposition of mosquitoes to an infectious blood meal containing ZIKV. Here, we report the isolation in cell culture of ZIKV obtained from different body parts of wild-caught female mosquitoes (Ae. aegypti, Ae. vexans, Cx. quinquefasciatus, Cx. coronator, and Cx. tarsalis) and whole male mosquitoes (Ae. aegypti and Cx. quinquefasciatus) in Mexico. Importantly, this is the first report that shows the presence of the virus in the salivary glands of the wild-caught female mosquitoes species, Cx. coronator, Cx. tarsalis, and Ae. vexans. Our findings strongly suggest that all the species reported herein are potential vectors for ZIKV.

Peridomestic Aedes malayensis and Aedes albopictus are capable vectors of arboviruses in cities.

PubMed

Mendenhall, Ian H; Manuel, Menchie; Moorthy, Mahesh; Lee, Theodore T M; Low, Dolyce H W; Missé, Dorothée; Gubler, Duane J; Ellis, Brett R; Ooi, Eng Eong; Pompon, Julien

2017-06-01

Dengue and chikungunya are global re-emerging mosquito-borne diseases. In Singapore, sustained vector control coupled with household improvements reduced domestic mosquito populations for the past 45 years, particularly the primary vector Aedes aegypti. However, while disease incidence was low for the first 30 years following vector control implementation, outbreaks have re-emerged in the past 15 years. Epidemiological observations point to the importance of peridomestic infection in areas not targeted by control programs. We investigated the role of vectors in peri-domestic areas. We carried out entomological surveys to identify the Aedes species present in vegetated sites in highly populated areas and determine whether mosquitoes were present in open-air areas frequented by people. We compared vector competence of Aedes albopictus and Aedes malayensis with Ae. aegypti after oral infection with sympatric dengue serotype 2 and chikungunya viruses. Mosquito saliva was tested for the presence of infectious virus particles as a surrogate for transmission following oral infection. We identified Aedes albopictus and Aedes malayensis throughout Singapore and quantified their presence in forested and opened grassy areas. Both Ae. albopictus and Ae. malayensis can occupy sylvatic niches and were highly susceptible to both arboviruses. A majority of saliva of infected Ae. malayensis contained infectious particles for both viruses. Our study reveals the prevalence of competent vectors in peri-domestic areas, including Ae. malayensis for which we established the vector status. Epidemics can be driven by infection foci, which are epidemiologically enhanced in the context of low herd immunity, selective pressure on arbovirus transmission and the presence of infectious asymptomatic persons, all these conditions being present in Singapore. Learning from Singapore's vector control success that reduced domestic vector populations, but has not sustainably reduced arboviral incidence, we suggest including peri-domestic vectors in the scope of vector management.

Identification of candidate transmission-blocking antigen genes in Theileria annulata and related vector-borne apicomplexan parasites.

PubMed

Lempereur, Laetitia; Larcombe, Stephen D; Durrani, Zeeshan; Karagenc, Tulin; Bilgic, Huseyin Bilgin; Bakirci, Serkan; Hacilarlioglu, Selin; Kinnaird, Jane; Thompson, Joanne; Weir, William; Shiels, Brian

2017-06-05

Vector-borne apicomplexan parasites are a major cause of mortality and morbidity to humans and livestock globally. The most important disease syndromes caused by these parasites are malaria, babesiosis and theileriosis. Strategies for control often target parasite stages in the mammalian host that cause disease, but this can result in reservoir infections that promote pathogen transmission and generate economic loss. Optimal control strategies should protect against clinical disease, block transmission and be applicable across related genera of parasites. We have used bioinformatics and transcriptomics to screen for transmission-blocking candidate antigens in the tick-borne apicomplexan parasite, Theileria annulata. A number of candidate antigen genes were identified which encoded amino acid domains that are conserved across vector-borne Apicomplexa (Babesia, Plasmodium and Theileria), including the Pfs48/45 6-cys domain and a novel cysteine-rich domain. Expression profiling confirmed that selected candidate genes are expressed by life cycle stages within infected ticks. Additionally, putative B cell epitopes were identified in the T. annulata gene sequences encoding the 6-cys and cysteine rich domains, in a gene encoding a putative papain-family cysteine peptidase, with similarity to the Plasmodium SERA family, and the gene encoding the T. annulata major merozoite/piroplasm surface antigen, Tams1. Candidate genes were identified that encode proteins with similarity to known transmission blocking candidates in related parasites, while one is a novel candidate conserved across vector-borne apicomplexans and has a potential role in the sexual phase of the life cycle. The results indicate that a 'One Health' approach could be utilised to develop a transmission-blocking strategy effective against vector-borne apicomplexan parasites of animals and humans.

Habitat Management to Reduce Human Exposure to Trypanosoma cruzi and Western Conenose Bugs (Triatoma protracta).

PubMed

Shender, Lisa; Niemela, Michael; Conrad, Patricia; Goldstein, Tracey; Mazet, Jonna

2016-09-01

Chagas disease, which manifests as cardiomyopathy and severe gastrointestinal dysfunction, is caused by Trypanosoma cruzi, a vector-borne parasite. In California, the vector Triatoma protracta frequently colonizes woodrat (Neotoma spp.) lodges, but may also invade nearby residences, feeding upon humans and creating the dual risk of bite-induced anaphylaxis and T. cruzi transmission. Our research aimed to assess T. cruzi presence in woodrats in a previously unstudied northern California area, statistically evaluate woodrat microhabitat use with respect to vegetation parameters, and provide guidance for habitat modifications to mitigate public health risks associated with Tr. protracta exposure. Blood samples from big-eared woodrats (N. macrotis) trapped on rural private properties yielded a T. cruzi prevalence of 14.3%. Microhabitat analyses suggest that modifying vegetation to reduce understory density within a 40 meter radius of human residences might minimize woodrat lodge construction within this buffer area, potentially decreasing human exposure to Tr. protracta.

A geographical information system-based multicriteria evaluation to map areas at risk for Rift Valley fever vector-borne transmission in Italy.

PubMed

Tran, A; Ippoliti, C; Balenghien, T; Conte, A; Gely, M; Calistri, P; Goffredo, M; Baldet, T; Chevalier, V

2013-11-01

Rift Valley fever (RVF) is a severe mosquito-borne disease that is caused by a Phlebovirus (Bunyaviridae) and affects domestic ruminants and humans. Recently, its distribution widened, threatening Europe. The probability of the introduction and large-scale spread of Rift Valley fever virus (RVFV) in Europe is low, but localized RVF outbreaks may occur in areas where populations of ruminants and potential vectors are present. In this study, we assumed the introduction of the virus into Italy and focused on the risk of vector-borne transmission of RVFV to three main European potential hosts (cattle, sheep and goats). Five main potential mosquito vectors belonging to the Culex and Aedes genera that are present in Italy were identified in a literature review. We first modelled the geographical distribution of these five species based on expert knowledge and using land cover as a proxy of mosquito presence. The mosquito distribution maps were compared with field mosquito collections from Italy to validate the model. Next, the risk of RVFV transmission was modelled using a multicriteria evaluation (MCE) approach, integrating expert knowledge and the results of a literature review on host sensitivity and vector competence, feeding behaviour and abundance. A sensitivity analysis was performed to assess the robustness of the results with respect to expert choices. The resulting maps include (i) five maps of the vector distribution, (ii) a map of suitable areas for vector-borne transmission of RVFV and (iii) a map of the risk of RVFV vector-borne transmission to sensitive hosts given a viral introduction. Good agreement was found between the modelled presence probability and the observed presence or absence of each vector species. The resulting RVF risk map highlighted strong spatial heterogeneity and could be used to target surveillance. In conclusion, the geographical information system (GIS)-based MCE served as a valuable framework and a flexible tool for mapping the areas at risk of a pathogen that is currently absent from a region. © 2013 Blackwell Verlag GmbH.

Disaggregating Tropical Disease Prevalence by Climatic and Vegetative Zones within Tropical West Africa.

PubMed

Beckley, Carl S; Shaban, Salisu; Palmer, Guy H; Hudak, Andrew T; Noh, Susan M; Futse, James E

2016-01-01

Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly infer that tropical diseases are uniformly prevalent has been partially overcome with solid epidemiologic data. This finer resolution data is important in multiple contexts, including understanding risk, predictive value in disease diagnosis, and population immunity. We hypothesized that within the context of a tropical climate, vector-borne pathogen prevalence would significantly differ according to zonal differences in rainfall, temperature, relative humidity and vegetation condition. We then determined if these environmental data were predictive of pathogen prevalence. First we determined the prevalence of three major pathogens of cattle, Anaplasma marginale, Babesia bigemina and Theileria spp, in the three vegetation zones where cattle are predominantly raised in Ghana: Guinea savannah, semi-deciduous forest, and coastal savannah. The prevalence of A. marginale was 63%, 26% for Theileria spp and 2% for B. bigemina. A. marginale and Theileria spp. were significantly more prevalent in the coastal savannah as compared to either the Guinea savanna or the semi-deciduous forest, supporting acceptance of the first hypothesis. To test the predictive power of environmental variables, the data over a three year period were considered in best subsets multiple linear regression models predicting prevalence of each pathogen. Corrected Akaike Information Criteria (AICc) were assigned to the alternative models to compare their utility. Competitive models for each response were averaged using AICc weights. Rainfall was most predictive of pathogen prevalence, and EVI also contributed to A. marginale and B. bigemina prevalence. These findings support the utility of environmental data for understanding vector-borne disease epidemiology on a regional level within a tropical environment.

Disaggregating Tropical Disease Prevalence by Climatic and Vegetative Zones within Tropical West Africa

PubMed Central

Beckley, Carl S.; Shaban, Salisu; Palmer, Guy H.; Hudak, Andrew T.; Noh, Susan M.; Futse, James E.

2016-01-01

Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly infer that tropical diseases are uniformly prevalent has been partially overcome with solid epidemiologic data. This finer resolution data is important in multiple contexts, including understanding risk, predictive value in disease diagnosis, and population immunity. We hypothesized that within the context of a tropical climate, vector-borne pathogen prevalence would significantly differ according to zonal differences in rainfall, temperature, relative humidity and vegetation condition. We then determined if these environmental data were predictive of pathogen prevalence. First we determined the prevalence of three major pathogens of cattle, Anaplasma marginale, Babesia bigemina and Theileria spp, in the three vegetation zones where cattle are predominantly raised in Ghana: Guinea savannah, semi-deciduous forest, and coastal savannah. The prevalence of A. marginale was 63%, 26% for Theileria spp and 2% for B. bigemina. A. marginale and Theileria spp. were significantly more prevalent in the coastal savannah as compared to either the Guinea savanna or the semi-deciduous forest, supporting acceptance of the first hypothesis. To test the predictive power of environmental variables, the data over a three year period were considered in best subsets multiple linear regression models predicting prevalence of each pathogen. Corrected Akaike Information Criteria (AICc) were assigned to the alternative models to compare their utility. Competitive models for each response were averaged using AICc weights. Rainfall was most predictive of pathogen prevalence, and EVI also contributed to A. marginale and B. bigemina prevalence. These findings support the utility of environmental data for understanding vector-borne disease epidemiology on a regional level within a tropical environment. PMID:27022740

Tick-Pathogen Interactions and Vector Competence: Identification of Molecular Drivers for Tick-Borne Diseases

PubMed Central

de la Fuente, José; Antunes, Sandra; Bonnet, Sarah; Cabezas-Cruz, Alejandro; Domingos, Ana G.; Estrada-Peña, Agustín; Johnson, Nicholas; Kocan, Katherine M.; Mansfield, Karen L.; Nijhof, Ard M.; Papa, Anna; Rudenko, Nataliia; Villar, Margarita; Alberdi, Pilar; Torina, Alessandra; Ayllón, Nieves; Vancova, Marie; Golovchenko, Maryna; Grubhoffer, Libor; Caracappa, Santo; Fooks, Anthony R.; Gortazar, Christian; Rego, Ryan O. M.

2017-01-01

Ticks and the pathogens they transmit constitute a growing burden for human and animal health worldwide. Vector competence is a component of vectorial capacity and depends on genetic determinants affecting the ability of a vector to transmit a pathogen. These determinants affect traits such as tick-host-pathogen and susceptibility to pathogen infection. Therefore, the elucidation of the mechanisms involved in tick-pathogen interactions that affect vector competence is essential for the identification of molecular drivers for tick-borne diseases. In this review, we provide a comprehensive overview of tick-pathogen molecular interactions for bacteria, viruses, and protozoa affecting human and animal health. Additionally, the impact of tick microbiome on these interactions was considered. Results show that different pathogens evolved similar strategies such as manipulation of the immune response to infect vectors and facilitate multiplication and transmission. Furthermore, some of these strategies may be used by pathogens to infect both tick and mammalian hosts. Identification of interactions that promote tick survival, spread, and pathogen transmission provides the opportunity to disrupt these interactions and lead to a reduction in tick burden and the prevalence of tick-borne diseases. Targeting some of the similar mechanisms used by the pathogens for infection and transmission by ticks may assist in development of preventative strategies against multiple tick-borne diseases. PMID:28439499

Global Change and Human Vulnerability to Vector-Borne Diseases

PubMed Central

Sutherst, Robert W.

2004-01-01

Global change includes climate change and climate variability, land use, water storage and irrigation, human population growth and urbanization, trade and travel, and chemical pollution. Impacts on vector-borne diseases, including malaria, dengue fever, infections by other arboviruses, schistosomiasis, trypanosomiasis, onchocerciasis, and leishmaniasis are reviewed. While climate change is global in nature and poses unknown future risks to humans and natural ecosystems, other local changes are occurring more rapidly on a global scale and are having significant effects on vector-borne diseases. History is invaluable as a pointer to future risks, but direct extrapolation is no longer possible because the climate is changing. Researchers are therefore embracing computer simulation models and global change scenarios to explore the risks. Credible ranking of the extent to which different vector-borne diseases will be affected awaits a rigorous analysis. Adaptation to the changes is threatened by the ongoing loss of drugs and pesticides due to the selection of resistant strains of pathogens and vectors. The vulnerability of communities to the changes in impacts depends on their adaptive capacity, which requires both appropriate technology and responsive public health systems. The availability of resources in turn depends on social stability, economic wealth, and priority allocation of resources to public health. PMID:14726459

The risk of vector-borne infections in sled dogs associated with existing and new endemic areas in Poland: Part 1: A population study on sled dogs during the racing season.

PubMed

Bajer, Anna; Mierzejewska, Ewa J; Rodo, Anna; Bednarska, Malgorzata; Kowalec, Maciej; Welc-Falęciak, Renata

2014-05-28

The achievements of sled dogs in competitions depend both on their training and on their health. Vector-borne infections may lead to anaemia, affect joints or heart muscle or even cause death. Between December 2009 and October 2010, one hundred and twenty six individual blood samples were collected from 26 sled dog kennels situated in different regions of Poland. The majority of samples were taken during the racing season (winter 2009/10). The prevalences of 3 vector-borne infections- including 2 'old pathogens' Anaplasma phagocytophilum and Babesia canis, and 'new pathogen' Hepatozoon canis-were estimated in sled dogs using PCR and nested PCR. Additionally, 25 serum samples originating from a subset of 3 kennels situated in a tick-borne encephalitis (TBE) endemic area (Mazowiecki region), were tested for antibodies against the tick-borne encephalitis virus (TBEV). Because of the recently reported occurrence of Dirofilaria repens in Central Poland and that of fatal cases of unknown aetiology in two of the kennels, blood samples collected from dogs at these kennels in 2010 and in February-May 2013 and from two unaffected kennels were checked for evidence of presence of this parasite. Babesia canis DNA was detected in 11 sled dogs (4 with clinical babesiosis, 7 asymptomatic; 8.7%) inhabiting mainly endemic regions of Poland (9/11 cases). Three serum samples originating from one location tested positive for TBEV antibodies (total seroprevalence: 3/25=12%, local seroprevalence: 3/12=25%). The risk of TBEV infection was associated with previous B. canis infections. Dirofilaria repens DNA was detected in 15 dogs (44%). Prevalence was especially high in two sled dog kennels situated near Grodzisk Mazowiecki (50-57%). No blood samples tested positive for A. phagocytophilum or H. canis DNA. The present study has established that the prevalence of vector-borne pathogens in working sled dogs is significant in the endemic regions and has justified the important role of surveillance of reservoir hosts in the epidemiology of TBE. Our results emphasize the need for regular monitoring for the presence of D. repens. Copyright © 2014 Elsevier B.V. All rights reserved.

Global Transport Networks and Infectious Disease Spread

PubMed Central

Tatem, A.J.; Rogers, D.J.; Hay, S.I.

2011-01-01

Air, sea and land transport networks continue to expand in reach, speed of travel and volume of passengers and goods carried. Pathogens and their vectors can now move further, faster and in greater numbers than ever before. Three important consequences of global transport network expansion are infectious disease pandemics, vector invasion events and vector-borne pathogen importation. This review briefly examines some of the important historical examples of these disease and vector movements, such as the global influenza pandemics, the devastating Anopheles gambiae invasion of Brazil and the recent increases in imported Plasmodium falciparum malaria cases. We then outline potential approaches for future studies of disease movement, focussing on vector invasion and vector-borne disease importation. Such approaches allow us to explore the potential implications of international air travel, shipping routes and other methods of transport on global pathogen and vector traffic. PMID:16647974

Canine infection with Dirofilaria immitis, Borrelia burgdorferi, Anaplasma spp., and Ehrlichia spp. in the United States, 2010–2012

PubMed Central

2014-01-01

Background The geographic distribution of canine infection with vector-borne disease agents in the United States appears to be expanding. Methods To provide an updated assessment of geographic trends in canine infection with Dirofilaria immitis, Borrelia burgdorferi, Ehrlichia spp., and Anaplasma spp., we evaluated results from an average of 3,588,477 dogs tested annually by veterinarians throughout the United States from 2010 – 2012. Results As in an earlier summary report, the percent positive test results varied by agent and region, with antigen of D. immitis and antibody to Ehrlichia spp. most commonly identified in the Southeast (2.9% and 3.2%, respectively) and antibody to both B. burgdorferi and Anaplasma spp. most commonly identified in the Northeast (13.3% and 7.1%, respectively) and upper Midwest (4.4% and 3.9%, respectively). Percent positive test results for D. immitis antigen were lower in every region considered, including in the Southeast, than previously reported. Percent positive test results for antibodies to B. burgdorferi and Ehrlichia spp. were higher nationally than previously reported, and, for antibodies to Anaplasma spp., were higher in the Northeast but lower in the Midwest and West, than in the initial report. Annual reports of human cases of Lyme disease, ehrlichiosis, and anaplasmosis were associated with percent positive canine test results by state for each respective tick-borne disease agent (R2 = 0.701, 0.457, and 0.314, respectively). Within endemic areas, percent positive test results for all three tick-borne agents demonstrated evidence of geographic expansion. Conclusions Continued national monitoring of canine test results for vector-borne zoonotic agents is an important tool for accurately mapping the geographic distribution of these agents, and greatly aids our understanding of the veterinary and public health threats they pose. PMID:24886589

Properties of the tick-borne encephalitis virus population during persistent infection of ixodid ticks and tick cell lines.

PubMed

Belova, Oxana A; Litov, Alexander G; Kholodilov, Ivan S; Kozlovskaya, Liubov I; Bell-Sakyi, Lesley; Romanova, Lidiya Iu; Karganova, Galina G

2017-10-01

Tick-borne encephalitis virus (TBEV) is the causative agent of tick-borne encephalitis (TBE), a vector-borne zoonotic neuroinfection. For successful circulation in natural foci the virus has to survive in the vector for a long period of time. Information about the effect of long-term infection of ticks on properties of the viral population is of great importance. In recent years, changes in the eco-epidemiology of TBEV due to changes in distribution of ixodid ticks have been observed. These changes in TBEV-endemic areas could result in a shift of the main tick vector species, which in turn may lead to changes in properties of the virus. In the present study we evaluated the selective pressure on the TBEV population during persistent infection of various species of ticks and tick cell lines. TBEV effectively replicated and formed persistent infection in ticks and tick cell lines of the vector species (Ixodes spp.), potential vectors (Dermacentor spp.) and non-vector ticks (Hyalomma spp.). During TBEV persistence in Ixodes and Dermacentor ticks, properties of the viral population remained virtually unchanged. In contrast, persistent TBEV infection of tick cell lines from both vector and non-vector ticks favoured selection of viral variants with low neuroinvasiveness for laboratory mice and substitutions in the E protein that increased local positive charge of the virion. Thus, selective pressure on viral population may differ in ticks and tick cell lines during persistent infection. Nevertheless, virus variants with properties of the original strain adapted to mouse CNS were not eliminated from the viral population during long-term persistence of TBEV in ticks and tick cell lines. Copyright © 2017 Elsevier GmbH. All rights reserved.

Full-Genome Characterisation of Orungo, Lebombo and Changuinola Viruses Provides Evidence for Co-Evolution of Orbiviruses with Their Arthropod Vectors

PubMed Central

Mohd Jaafar, Fauziah; Belhouchet, Mourad; Belaganahalli, Manjunatha; Tesh, Robert B.; Mertens, Peter P. C.; Attoui, Houssam

2014-01-01

The complete genomes of Orungo virus (ORUV), Lebombo virus (LEBV) and Changuinola virus (CGLV) were sequenced, confirming that they each encode 11 distinct proteins (VP1-VP7 and NS1-NS4). Phylogenetic analyses of cell-attachment protein ‘outer-capsid protein 1′ (OC1), show that orbiviruses fall into three large groups, identified as: VP2(OC1), in which OC1 is the 2nd largest protein, including the Culicoides transmitted orbiviruses; VP3(OC1), which includes the mosquito transmitted orbiviruses; and VP4(OC1) which includes the tick transmitted viruses. Differences in the size of OC1 between these groups, places the T2 ‘subcore-shell protein’ as the third largest protein ‘VP3(T2)’ in the first of these groups, but the second largest protein ‘VP3(T2)’ in the other two groups. ORUV, LEBV and CGLV all group with the Culicoides-borne VP2(OC1)/VP3(T2) viruses. The G+C content of the ORUV, LEBV and CGLV genomes is also similar to that of the Culicoides-borne, rather than the mosquito-borne, or tick borne orbiviruses. These data suggest that ORUV and LEBV are Culicoides- rather than mosquito-borne. Multiple isolations of CGLV from sand flies suggest that they are its primary vector. OC1 of the insect-borne orbiviruses is approximately twice the size of the equivalent protein of the tick borne viruses. Together with internal sequence similarities, this suggests its origin by duplication (concatermerisation) of a smaller OC1 from an ancestral tick-borne orbivirus. Phylogenetic comparisons showing linear relationships between the dates of evolutionary-separation of their vector species, and genetic-distances between tick-, mosquito- or Culicoides-borne virus-groups, provide evidence for co-evolution of the orbiviruses with their arthropod vectors. PMID:24475112

Phylogeny of the Genus Flavivirus

PubMed Central

Kuno, Goro; Chang, Gwong-Jen J.; Tsuchiya, K. Richard; Karabatsos, Nick; Cropp, C. Bruce

1998-01-01

We undertook a comprehensive phylogenetic study to establish the genetic relationship among the viruses of the genus Flavivirus and to compare the classification based on molecular phylogeny with the existing serologic method. By using a combination of quantitative definitions (bootstrap support level and the pairwise nucleotide sequence identity), the viruses could be classified into clusters, clades, and species. Our phylogenetic study revealed for the first time that from the putative ancestor two branches, non-vector and vector-borne virus clusters, evolved and from the latter cluster emerged tick-borne and mosquito-borne virus clusters. Provided that the theory of arthropod association being an acquired trait was correct, pairwise nucleotide sequence identity among these three clusters provided supporting data for a possibility that the non-vector cluster evolved first, followed by the separation of tick-borne and mosquito-borne virus clusters in that order. Clades established in our study correlated significantly with existing antigenic complexes. We also resolved many of the past taxonomic problems by establishing phylogenetic relationships of the antigenically unclassified viruses with the well-established viruses and by identifying synonymous viruses. PMID:9420202

Phylogeny of the genus Flavivirus.

PubMed

Kuno, G; Chang, G J; Tsuchiya, K R; Karabatsos, N; Cropp, C B

1998-01-01

We undertook a comprehensive phylogenetic study to establish the genetic relationship among the viruses of the genus Flavivirus and to compare the classification based on molecular phylogeny with the existing serologic method. By using a combination of quantitative definitions (bootstrap support level and the pairwise nucleotide sequence identity), the viruses could be classified into clusters, clades, and species. Our phylogenetic study revealed for the first time that from the putative ancestor two branches, non-vector and vector-borne virus clusters, evolved and from the latter cluster emerged tick-borne and mosquito-borne virus clusters. Provided that the theory of arthropod association being an acquired trait was correct, pairwise nucleotide sequence identity among these three clusters provided supporting data for a possibility that the non-vector cluster evolved first, followed by the separation of tick-borne and mosquito-borne virus clusters in that order. Clades established in our study correlated significantly with existing antigenic complexes. We also resolved many of the past taxonomic problems by establishing phylogenetic relationships of the antigenically unclassified viruses with the well-established viruses and by identifying synonymous viruses.

Molecular survey of canine vector-borne diseases in stray dogs in Thailand.

PubMed

Liu, Mingming; Ruttayaporn, Ngasaman; Saechan, Vannarat; Jirapattharasate, Charoonluk; Vudriko, Patrick; Moumouni, Paul Franck Adjou; Cao, Shinuo; Inpankaew, Tawin; Ybañez, Adrian P; Suzuki, Hiroshi; Xuan, Xuenan

2016-08-01

Despite the large population of stray dogs in Thailand, there is limited information on the prevalence of canine vector-borne diseases (CVBDs). In this study, a molecular survey was conducted to determine the prevalence of Babesia spp., Ehrlichia canis, Hepatozoon spp., Anaplasma platys and Mycoplasma spp. in dogs in Thailand. Of the 181 dog blood samples tested by PCR, 78/181 (43.1%) were found to be infected with one or more pathogens. The overall prevalence rates of Mycoplasma spp., Hepatozoon spp., Babesia spp., A. platys and E. canis infections were 19.9%, 18.8%, 9.4%, 4.4% and 3.9%, respectively. To the authors' knowledge, this is the first report of Mycoplasma infection in Thailand in dogs. The current findings are important for future surveillance of CVBDs and designing appropriate approaches for diagnosis and control for the diseases in Thailand. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

R0 for vector-borne diseases: impact of the assumption for the duration of the extrinsic incubation period.

PubMed

Hartemink, Nienke; Cianci, Daniela; Reiter, Paul

2015-03-01

Mathematical modeling and notably the basic reproduction number R0 have become popular tools for the description of vector-borne disease dynamics. We compare two widely used methods to calculate the probability of a vector to survive the extrinsic incubation period. The two methods are based on different assumptions for the duration of the extrinsic incubation period; one method assumes a fixed period and the other method assumes a fixed daily rate of becoming infectious. We conclude that the outcomes differ substantially between the methods when the average life span of the vector is short compared to the extrinsic incubation period.

Cross-sectional survey of health management and prevalence of vector-borne diseases, endoparasites and ectoparasites in Samoan dogs.

PubMed

Carslake, R J; Hill, K E; Sjölander, K; Hii, S F; Prattley, D; Acke, E

2017-12-01

To determine the prevalence of selected canine vector-borne diseases (Leishmania infantum, Anaplasma spp., Ehrlichia canis, Borrelia burgdorferi and Dirofilaria immitis) and endo- and ectoparasites in Samoan dogs presenting for surgical sterilisation and to report on the general health management of the dogs. This study was a prospective serological cross-sectional survey. Management data were obtained for 242 dogs by interview with their owners. Blood samples were collected from 237 dogs and screened for the canine vector-borne diseases using point-of-care qualitative ELISA assays. Anaplasma spp. positive samples were screened by PCR and sequenced for species identification. Rectal faecal samples were collected from 204 dogs for faecal flotation and immunofluorescent antibody tests were performed for Giardia and Cryptosporidium spp. on a subset of 93 faecal samples. The skin and coat of 221 dogs were examined for presence of ectoparasites. The D. immitis antigen was detected in 46.8% (111/237) of dogs. Seroprevalence of Anaplasma spp. was 8.4% (20/237); A. platys was confirmed by PCR. Prevalence of hookworm was 92.6% (185/205) and Giardia was 29.0% (27/93). Ectoparasites were detected on 210/221 (95.0%) of dogs examined and 228/242 dogs (94.2%) had previously never received any preventative medication. There was a very high prevalence of D. immitis, hookworm and external parasites in Samoan dogs, and prophylactic medication is rarely administered. This is the first report confirming A. platys in Samoa and the South Pacific islands. The public health implications of poor management of the dogs should be considered and investigated further. © 2017 Australian Veterinary Association.

Trypanosoma cruzi and Chagas' Disease in the United States

PubMed Central

Bern, Caryn; Kjos, Sonia; Yabsley, Michael J.; Montgomery, Susan P.

2011-01-01

Summary: Chagas' disease is caused by the protozoan parasite Trypanosoma cruzi and causes potentially life-threatening disease of the heart and gastrointestinal tract. The southern half of the United States contains enzootic cycles of T. cruzi, involving 11 recognized triatomine vector species. The greatest vector diversity and density occur in the western United States, where woodrats are the most common reservoir; other rodents, raccoons, skunks, and coyotes are also infected with T. cruzi. In the eastern United States, the prevalence of T. cruzi is highest in raccoons, opossums, armadillos, and skunks. A total of 7 autochthonous vector-borne human infections have been reported in Texas, California, Tennessee, and Louisiana; many others are thought to go unrecognized. Nevertheless, most T. cruzi-infected individuals in the United States are immigrants from areas of endemicity in Latin America. Seven transfusion-associated and 6 organ donor-derived T. cruzi infections have been documented in the United States and Canada. As improved control of vector- and blood-borne T. cruzi transmission decreases the burden in countries where the disease is historically endemic and imported Chagas' disease is increasingly recognized outside Latin America, the United States can play an important role in addressing the altered epidemiology of Chagas' disease in the 21st century. PMID:21976603

Current status of genome editing in vector mosquitoes: A review.

PubMed

Reegan, Appadurai Daniel; Ceasar, Stanislaus Antony; Paulraj, Michael Gabriel; Ignacimuthu, Savarimuthu; Al-Dhabi, Naif Abdullah

2017-01-16

Mosquitoes pose a major threat to human health as they spread many deadly diseases like malaria, dengue, chikungunya, filariasis, Japanese encephalitis and Zika. Identification and use of novel molecular tools are essential to combat the spread of vector borne diseases. Genome editing tools have been used for the precise alterations of the gene of interest for producing the desirable trait in mosquitoes. Deletion of functional genes or insertion of toxic genes in vector mosquitoes will produce either knock-out or knock-in mutants that will check the spread of vector-borne diseases. Presently, three types of genome editing tools viz., zinc finger nuclease (ZFN), transcription activator-like effector nucleases (TALEN) and clustered regulatory interspaced short palindromic repeats (CRISPR) and CRISPR associated protein 9 (Cas9) are widely used for the editing of the genomes of diverse organisms. These tools are also applied in vector mosquitoes to control the spread of vector-borne diseases. A few studies have been carried out on genome editing to control the diseases spread by vector mosquitoes and more studies need to be performed with the utilization of more recently invented tools like CRISPR/Cas9 to combat the spread of deadly diseases by vector mosquitoes. The high specificity and flexibility of CRISPR/Cas9 system may offer possibilities for novel genome editing for the control of important diseases spread by vector mosquitoes. In this review, we present the current status of genome editing research on vector mosquitoes and also discuss the future applications of vector mosquito genome editing to control the spread of vectorborne diseases.

Flea-Borne Rickettsioses in the North of Caldas Province, Colombia

PubMed Central

Montoya, Viviana; Martínez, Alejandra; Mercado, Marcela; De la Ossa, Alberto; Vélez, Carolina; Estrada, Gloria; Pérez, Jorge E.; Faccini-Martínez, Alvaro A.; Labruna, Marcelo B.; Valbuena, Gustavo

2013-01-01

Abstract Rickettsia typhi and R. felis are the etiological agents of murine typhus and flea-borne spotted fever, respectively. Both are emerging acute febrile zoonotic diseases for which fleas are vectors; they also have similar clinical characteristics and global distribution. In 2005, we identified the circulation of murine typhus in 6 towns within the mountainous coffee-growing area north of Caldas, Colombia. We now report the specific seroprevalence against R. typhi and R. felis, and associated risk factors in 7 towns of this province. The combined seroprevalence against the 2 flea-borne rickettsioses is the highest yet reported in the literature: 71.7% (17.8% for R. felis, 25.2% for R. typhi, and 28.7% for both). We also report a prospective analysis of 26 patients with a febrile illness compatible with rickettsioses, including murine typhus; 9 of these patients had a rickettsiosis. This supports our sero-epidemiological results and highlights the diagnostic complexity of febrile syndromes in this region. PMID:23473218

Opportunities for Improved Chagas Disease Vector Control Based on Knowledge, Attitudes and Practices of Communities in the Yucatan Peninsula, Mexico

PubMed Central

Rosecrans, Kathryn; Cruz-Martin, Gabriela; King, Ashley; Dumonteil, Eric

2014-01-01

Background Chagas disease is a vector-borne parasitic disease of major public health importance. Current prevention efforts are based on triatomine vector control to reduce transmission to humans. Success of vector control interventions depends on their acceptability and value to affected communities. We aimed to identify opportunities for and barriers to improved vector control strategies in the Yucatan peninsula, Mexico. Methodology/principal findings We employed a sequence of qualitative and quantitative research methods to investigate knowledge, attitudes and practices surrounding Chagas disease, triatomines and vector control in three rural communities. Our combined data show that community members are well aware of triatomines and are knowledgeable about their habits. However, most have a limited understanding of the transmission dynamics and clinical manifestations of Chagas disease. While triatomine control is not a priority for community members, they frequently use domestic insecticide products including insecticide spray, mosquito coils and plug-in repellents. Families spend about $32 US per year on these products. Alternative methods such as yard cleaning and window screens are perceived as desirable and potentially more effective. Screens are nonetheless described as unaffordable, in spite of a cost comparable to the average annual spending on insecticide products. Conclusion/Significance Further education campaigns and possibly financing schemes may lead families to redirect their current vector control spending from insecticide products to window screens. Also, synergism with mosquito control efforts should be further explored to motivate community involvement and ensure sustainability of Chagas disease vector control. PMID:24676038

Climate Predictors of the Spatial Distribution of Human Plague Cases in the West Nile Region of Uganda

PubMed Central

MacMillan, Katherine; Monaghan, Andrew J.; Apangu, Titus; Griffith, Kevin S.; Mead, Paul S.; Acayo, Sarah; Acidri, Rogers; Moore, Sean M.; Mpanga, Joseph Tendo; Enscore, Russel E.; Gage, Kenneth L.; Eisen, Rebecca J.

2012-01-01

East Africa has been identified as a region where vector-borne and zoonotic diseases are most likely to emerge or re-emerge and where morbidity and mortality from these diseases is significant. Understanding when and where humans are most likely to be exposed to vector-borne and zoonotic disease agents in this region can aid in targeting limited prevention and control resources. Often, spatial and temporal distributions of vectors and vector-borne disease agents are predictable based on climatic variables. However, because of coarse meteorological observation networks, appropriately scaled and accurate climate data are often lacking for Africa. Here, we use a recently developed 10-year gridded meteorological dataset from the Advanced Weather Research and Forecasting Model to identify climatic variables predictive of the spatial distribution of human plague cases in the West Nile region of Uganda. Our logistic regression model revealed that within high elevation sites (above 1,300 m), plague risk was positively associated with rainfall during the months of February, October, and November and negatively associated with rainfall during the month of June. These findings suggest that areas that receive increased but not continuous rainfall provide ecologically conducive conditions for Yersinia pestis transmission in this region. This study serves as a foundation for similar modeling efforts of other vector-borne and zoonotic disease in regions with sparse observational meteorologic networks. PMID:22403328

Emergence and Prevalence of Human Vector-Borne Diseases in Sink Vector Populations

PubMed Central

Rascalou, Guilhem; Pontier, Dominique; Menu, Frédéric; Gourbière, Sébastien

2012-01-01

Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining ‘source’ populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining ‘sink’ vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15–55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale. PMID:22629337

Fusion of SAR and Optical Imagery for Studying the Eco-Epidemiology of Vector-Borne Diseases in Tropical Countries

NASA Astrophysics Data System (ADS)

Catry, Thibault; Li, Zhichao; Roux, Emmanuel; Herreteau, Vincent; Revillion, Christophe; Dessay, Nadine

2016-08-01

Vector-borne diseases like malaria represent a major public health issue worldwide. Other mosquito-borne diseases affect more and more countries and people, with effects on health which are not all identified yet. Recent developments in the field of remote-sensing allow to consider overriding the existing limits of studying such diseases in tropical regions, where cloud and vegetation cover often prevent to identify and characterize environmental features.We highlight the potential of SAR-optical fusion for the mapping of land cover, the identification of wetlands, and the monitoring of environmental changes in different habitats related to vector-borne diseases in the French Guiana - Brazil cross-border area. This study is the foundation of a landscape-based model of malaria transmission risk. Environmental factors, together with epidemiological, socio-economic, behavioral, demographics, and entomological ones, contribute to assess risks related to such pathologies and support disease control and decision-making by local public health actors.

Zoonotic intestinal parasites and vector-borne pathogens in Italian shelter and kennel dogs.

PubMed

Traversa, Donato; Di Cesare, Angela; Simonato, Giulia; Cassini, Rudi; Merola, Carmine; Diakou, Anastasia; Halos, Lénaïg; Beugnet, Frederic; Frangipane di Regalbono, Antonio

2017-04-01

This study investigated the presence of zoonotic parasites and vector-borne pathogens in dogs housed in kennels and shelters from four sites of Italy. A total of 150 adoptable dogs was examined with different microscopic, serological and molecular methods. Overall 129 dogs (86%) were positive for one or more parasites and/or pathogens transmitted by ectoparasites. Forty-eight (32%) were positive for one infection, while 81 (54%) for more than one pathogen. The most common zoonotic helminths recorded were hookworms, roundworms and Capillaria aerophila, followed by mosquito-borne Dirofilaria spp. and Dipylidium caninum. One hundred and thirteen (77.9%), 6 (4.1%) and 2 (1.4%) dogs were positive for Rickettsia spp., Leishmania infantum and Anaplasma spp., respectively. The results show that dogs living in rescue facilities from the studied areas may be infected by many zoonotic internal parasites and vector-borne pathogens, and that control measures should be implemented. Copyright © 2017 Elsevier Ltd. All rights reserved.

Estimated effects of projected climate change on the basic reproductive number of the Lyme disease vector Ixodes scapularis.

PubMed

Ogden, Nicholas H; Radojevic, Milka; Wu, Xiaotian; Duvvuri, Venkata R; Leighton, Patrick A; Wu, Jianhong

2014-06-01

The extent to which climate change may affect human health by increasing risk from vector-borne diseases has been under considerable debate. We quantified potential effects of future climate change on the basic reproduction number (R0) of the tick vector of Lyme disease, Ixodes scapularis, and explored their importance for Lyme disease risk, and for vector-borne diseases in general. We applied observed temperature data for North America and projected temperatures using regional climate models to drive an I. scapularis population model to hindcast recent, and project future, effects of climate warming on R0. Modeled R0 increases were compared with R0 ranges for pathogens and parasites associated with variations in key ecological and epidemiological factors (obtained by literature review) to assess their epidemiological importance. R0 for I. scapularis in North America increased during the years 1971-2010 in spatio-temporal patterns consistent with observations. Increased temperatures due to projected climate change increased R0 by factors (2-5 times in Canada and 1.5-2 times in the United States), comparable to observed ranges of R0 for pathogens and parasites due to variations in strains, geographic locations, epidemics, host and vector densities, and control efforts. Climate warming may have co-driven the emergence of Lyme disease in northeastern North America, and in the future may drive substantial disease spread into new geographic regions and increase tick-borne disease risk where climate is currently suitable. Our findings highlight the potential for climate change to have profound effects on vectors and vector-borne diseases, and the need to refocus efforts to understand these effects.

Analytic calculation of finite-population reproductive numbers for direct- and vector-transmitted diseases with homogeneous mixing.

PubMed

Keegan, Lindsay; Dushoff, Jonathan

2014-05-01

The basic reproductive number, R0, provides a foundation for evaluating how various factors affect the incidence of infectious diseases. Recently, it has been suggested that, particularly for vector-transmitted diseases, R0 should be modified to account for the effects of finite host population within a single disease transmission generation. Here, we use a transmission factor approach to calculate such "finite-population reproductive numbers," under the assumption of homogeneous mixing, for both vector-borne and directly transmitted diseases. In the case of vector-borne diseases, we estimate finite-population reproductive numbers for both host-to-host and vector-to-vector generations, assuming that the vector population is effectively infinite. We find simple, interpretable formulas for all three of these quantities. In the direct case, we find that finite-population reproductive numbers diverge from R0 before R0 reaches half of the population size. In the vector-transmitted case, we find that the host-to-host number diverges at even lower values of R0, while the vector-to-vector number diverges very little over realistic parameter ranges.

A gravity model for the spread of a pollinator-borne plant pathogen.

PubMed

Ferrari, Matthew J; Bjørnstad, Ottar N; Partain, Jessica L; Antonovics, Janis

2006-09-01

Many pathogens of plants are transmitted by arthropod vectors whose movement between individual hosts is influenced by foraging behavior. Insect foraging has been shown to depend on both the quality of hosts and the distances between hosts. Given the spatial distribution of host plants and individual variation in quality, vector foraging patterns may therefore produce predictable variation in exposure to pathogens. We develop a "gravity" model to describe the spatial spread of a vector-borne plant pathogen from underlying models of insect foraging in response to host quality using the pollinator-borne smut fungus Microbotryum violaceum as a case study. We fit the model to spatially explicit time series of M. violaceum transmission in replicate experimental plots of the white campion Silene latifolia. The gravity model provides a better fit than a mean field model or a model with only distance-dependent transmission. The results highlight the importance of active vector foraging in generating spatial patterns of disease incidence and for pathogen-mediated selection for floral traits.

The role of temperature on the spatiotemporal distribution of West Nile virus in the United States

NASA Astrophysics Data System (ADS)

Horton, D. E.; Kilpatrick, A. M.; Ruybal, J.; Diffenbaugh, N. S.

2012-12-01

Determining the relationship between climatological factors and vector-borne pathogens remains a critical challenge. The recent arrival of the West Nile virus (WNV) to the Americas, coupled with an extensive climatological and disease observation network, offers the potential to improve our mechanistic understanding of climate's influence on vector-borne disease transmission. Since its introduction to the Americas in the summer of 1999, the West Nile Virus (WNV) has rapidly spread from coastal New York State, across the North American continent, and into Central and South America. To date, 13,385 cases of WNV-induced human neuroinvasive disease have been reported to the U.S. Centers for Disease Control, with approximately 1,267 fatalities attributed to viral infection (as of 31 July 2012). Of those infected, severe symptoms develop in only ~1 in 150 people, suggesting that the total U.S. population infected with WNV is on the order of 2 million. The transmission of WNV is predominantly vector-borne, with three mosquitoes of the Culex genus, pipiens, tarsalis, and quinquefasciatus, largely responsible for the spread of the pathogen between avian and human hosts and across the contiguous United States. In this contribution, we synthesize laboratory and local-scale field studies of the Culex vectors with observed and modeled climatological data in an attempt to determine the mechanistic influence of temperature on the spatiotemporal distribution of WNV incidence across the United States. Our preliminary results suggest that many of the physiological factors that determine the transmission intensity of WNV, including mosquito biting rate, vector competence, infection transition rate, and mosquito mortality rate, demonstrate direct temperature dependencies. Based on these results, we utilize bias-corrected outputs from late-20th and mid-21st century CMIP5 simulations to examine the influence of temperature on the distribution of WNV relative to other factors and to explore the potential changes to WNV transmission intensity in a warming climate.

Encephalitis, Ontario, Canada, 2002-2013.

PubMed

Parpia, Alyssa S; Li, Ye; Chen, Cynthia; Dhar, Badal; Crowcroft, Natasha S

2016-03-01

Encephalitis, a brain inflammation leading to severe illness and often death, is caused by >100 pathogens. To assess the incidence and trends of encephalitis in Ontario, Canada, we obtained data on 6,463 Ontario encephalitis hospitalizations from the hospital Discharge Abstract Database for April 2002-December 2013 and analyzed these data using multiple negative binomial regression. The estimated crude incidence of all-cause encephalitis in Ontario was ≈4.3 cases/100,000 persons/year. Incidence rates for infants <1 year of age and adults >65 years were 3.9 and 3.0 times that of adults 20-44 years of age, respectively. Incidence peaks during August-September in 2002 and 2012 resulted primarily from encephalitis of unknown cause and viral encephalitis. Encephalitis occurred more frequently in older age groups and less frequently in women in Ontario when compared to England, but despite differences in population, vector-borne diseases, climate, and geography, the epidemiology was overall remarkably similar in the two regions.

[Blood safety: malaria and blood donation in Africa].

PubMed

Tayou Tagny, C; Mbanya, D; Garraud, O; Lefrère, J-J

2007-11-01

Malaria is a principal cause of mortality in Africa and represents a major blood-borne disease. The studies made on the continent show that transfusion-associated malaria is highly prevalent in blood donors groups and that some risk factors and clinical manifestations are frequently observed. The disease is mostly asymptomatic and the signs are mild, which reduces significantly an efficient selection of the blood donors during the predonation interview and a secure supply of blood products. Furthermore, the lack of appropriate screening assays of the malaria in blood banks on the continent limit the diagnosis of the disease and hamper the blood safety. However, the prevention of transfusion-associated malaria is a frequently asked question. The destruction of the parasite in the blood bag and the recipient anti-malarial prophylaxis are the described possibilities, added to local programs against the vectors of the disease.

Tick-borne protozoa

USDA-ARS?s Scientific Manuscript database

Tick-borne protozoa impose a significant health burden on humans and animals throughout the world. The virulence of tick-borne protozoa, and the geographic distribution of their tick vectors and vertebrate hosts remain in flux as they adapt to changing environmental and climatic conditions. Babesios...

Nonstationary Influence of El Niño on the Synchronous Dengue Epidemics in Thailand

PubMed Central

Cazelles, Bernard; Chavez, Mario; McMichael, Anthony J; Hales, Simon

2005-01-01

Background Several factors, including environmental and climatic factors, influence the transmission of vector-borne diseases. Nevertheless, the identification and relative importance of climatic factors for vector-borne diseases remain controversial. Dengue is the world's most important viral vector-borne disease, and the controversy about climatic effects also applies in this case. Here we address the role of climate variability in shaping the interannual pattern of dengue epidemics. Methods and Findings We have analysed monthly data for Thailand from 1983 to 1997 using wavelet approaches that can describe nonstationary phenomena and that also allow the quantification of nonstationary associations between time series. We report a strong association between monthly dengue incidence in Thailand and the dynamics of El Niño for the 2–3-y periodic mode. This association is nonstationary, seen only from 1986 to 1992, and appears to have a major influence on the synchrony of dengue epidemics in Thailand. Conclusion The underlying mechanism for the synchronisation of dengue epidemics may resemble that of a pacemaker, in which intrinsic disease dynamics interact with climate variations driven by El Niño to propagate travelling waves of infection. When association with El Niño is strong in the 2–3-y periodic mode, one observes high synchrony of dengue epidemics over Thailand. When this association is absent, the seasonal dynamics become dominant and the synchrony initiated in Bangkok collapses. PMID:15839751

Identification and molecular characterization of spotted fever group rickettsiae in ticks collected from farm ruminants in Lebanon.

PubMed

Fernández de Mera, Isabel G; Blanda, Valeria; Torina, Alessandra; Dabaja, Mayssaa Fawaz; El Romeh, Ali; Cabezas-Cruz, Alejandro; de la Fuente, José

2018-01-01

Tick-borne diseases have become a world health concern, emerging with increasing incidence in recent decades. Spotted fever group (SFG) rickettsiae are tick-borne pathogens recognized as important agents of human tick-borne diseases worldwide. In this study, 88 adult ticks from the species Hyalomma anatolicum, Rhipicephalus annulatus, Rh. bursa, Rh. sanguineus sensu lato, and Rh. turanicus, were collected from farm ruminants in Lebanon, and SFG rickettsiae were molecularly identified and characterized in these ticks. The screening showed a prevalence of 68% for Rickettsia spp., including the species R. aeschlimannii, R. africae, R. massiliae and Candidatus R. barbariae, the latter considered an emerging member of the SFG rickettsiae. These findings contribute to a better knowledge of the distribution of these pathogens and demonstrate that SFG rickettsiae with public health relevance are found in ticks collected in Lebanon, where the widespread distribution of tick vectors and possible livestock animal hosts in contact with humans may favor transmission to humans. Few reports exist for some of the tick species identified here as being infected with SFG Rickettsia. Some of these tick species are proven vectors of the hosted rickettsiae, although this information is unknown for other of these species. Therefore, these results suggested further investigation on the vector competence of the tick species with unknown role in transmission of some of the pathogens identified in this study. Copyright © 2017 Elsevier GmbH. All rights reserved.

How will climate change pathways and mitigation options alter incidence of vector-borne diseases? A framework for leishmaniasis in South and Meso-America

PubMed Central

Masante, Dario; Golding, Nicholas; Pigott, David; Day, John C.; Ibañez-Bernal, Sergio; Kolb, Melanie; Jones, Laurence

2017-01-01

The enormous global burden of vector-borne diseases disproportionately affects poor people in tropical, developing countries. Changes in vector-borne disease impacts are often linked to human modification of ecosystems as well as climate change. For tropical ecosystems, the health impacts of future environmental and developmental policy depend on how vector-borne disease risks trade off against other ecosystem services across heterogeneous landscapes. By linking future socio-economic and climate change pathways to dynamic land use models, this study is amongst the first to analyse and project impacts of both land use and climate change on continental-scale patterns in vector-borne diseases. Models were developed for cutaneous and visceral leishmaniasis in the Americas—ecologically complex sand fly borne infections linked to tropical forests and diverse wild and domestic mammal hosts. Both diseases were hypothesised to increase with available interface habitat between forest and agricultural or domestic habitats and with mammal biodiversity. However, landscape edge metrics were not important as predictors of leishmaniasis. Models including mammal richness were similar in accuracy and predicted disease extent to models containing only climate and land use predictors. Overall, climatic factors explained 80% and land use factors only 20% of the variance in past disease patterns. Both diseases, but especially cutaneous leishmaniasis, were associated with low seasonality in temperature and precipitation. Since such seasonality increases under future climate change, particularly under strong climate forcing, both diseases were predicted to contract in geographical extent to 2050, with cutaneous leishmaniasis contracting by between 35% and 50%. Whilst visceral leishmaniasis contracted slightly more under strong than weak management for carbon, biodiversity and ecosystem services, future cutaneous leishmaniasis extent was relatively insensitive to future alternative socio-economic pathways. Models parameterised at narrower geographical scales may be more sensitive to land use pattern and project more substantial changes in disease extent under future alternative socio-economic pathways. PMID:29020041

How will climate change pathways and mitigation options alter incidence of vector-borne diseases? A framework for leishmaniasis in South and Meso-America.

PubMed

Purse, Bethan V; Masante, Dario; Golding, Nicholas; Pigott, David; Day, John C; Ibañez-Bernal, Sergio; Kolb, Melanie; Jones, Laurence

2017-01-01

The enormous global burden of vector-borne diseases disproportionately affects poor people in tropical, developing countries. Changes in vector-borne disease impacts are often linked to human modification of ecosystems as well as climate change. For tropical ecosystems, the health impacts of future environmental and developmental policy depend on how vector-borne disease risks trade off against other ecosystem services across heterogeneous landscapes. By linking future socio-economic and climate change pathways to dynamic land use models, this study is amongst the first to analyse and project impacts of both land use and climate change on continental-scale patterns in vector-borne diseases. Models were developed for cutaneous and visceral leishmaniasis in the Americas-ecologically complex sand fly borne infections linked to tropical forests and diverse wild and domestic mammal hosts. Both diseases were hypothesised to increase with available interface habitat between forest and agricultural or domestic habitats and with mammal biodiversity. However, landscape edge metrics were not important as predictors of leishmaniasis. Models including mammal richness were similar in accuracy and predicted disease extent to models containing only climate and land use predictors. Overall, climatic factors explained 80% and land use factors only 20% of the variance in past disease patterns. Both diseases, but especially cutaneous leishmaniasis, were associated with low seasonality in temperature and precipitation. Since such seasonality increases under future climate change, particularly under strong climate forcing, both diseases were predicted to contract in geographical extent to 2050, with cutaneous leishmaniasis contracting by between 35% and 50%. Whilst visceral leishmaniasis contracted slightly more under strong than weak management for carbon, biodiversity and ecosystem services, future cutaneous leishmaniasis extent was relatively insensitive to future alternative socio-economic pathways. Models parameterised at narrower geographical scales may be more sensitive to land use pattern and project more substantial changes in disease extent under future alternative socio-economic pathways.

Comparative field trial of alternative vector control strategies for non-domiciliated Triatoma dimidiata.

PubMed

Ferral, Jhibran; Chavez-Nuñez, Leysi; Euan-Garcia, Maria; Ramirez-Sierra, Maria Jesus; Najera-Vazquez, M Rosario; Dumonteil, Eric

2010-01-01

Chagas disease is a major vector-borne disease, and regional initiatives based on insecticide spraying have successfully controlled domiciliated vectors in many regions. Non-domiciliated vectors remain responsible for a significant transmission risk, and their control is a challenge. We performed a proof-of-concept field trial to test alternative strategies in rural Yucatan, Mexico. Follow-up of house infestation for two seasons following the interventions confirmed that insecticide spraying should be performed annually for the effective control of Triatoma dimidiata; however, it also confirmed that insect screens or long-lasting impregnated curtains may represent good alternative strategies for the sustained control of these vectors. Ecosystemic peridomicile management would be an excellent complementary strategy to improve the cost-effectiveness of interventions. Because these strategies would also be effective against other vector-borne diseases, such as malaria or dengue, they could be integrated within a multi-disease control program.

Climate change and vector-borne diseases: a regional analysis.

PubMed Central

Githeko, A. K.; Lindsay, S. W.; Confalonieri, U. E.; Patz, J. A.

2000-01-01

Current evidence suggests that inter-annual and inter-decadal climate variability have a direct influence on the epidemiology of vector-borne diseases. This evidence has been assessed at the continental level in order to determine the possible consequences of the expected future climate change. By 2100 it is estimated that average global temperatures will have risen by 1.0-3.5 degrees C, increasing the likelihood of many vector-borne diseases in new areas. The greatest effect of climate change on transmission is likely to be observed at the extremes of the range of temperatures at which transmission occurs. For many diseases these lie in the range 14-18 degrees C at the lower end and about 35-40 degrees C at the upper end. Malaria and dengue fever are among the most important vector-borne diseases in the tropics and subtropics; Lyme disease is the most common vector-borne disease in the USA and Europe. Encephalitis is also becoming a public health concern. Health risks due to climatic changes will differ between countries that have developed health infrastructures and those that do not. Human settlement patterns in the different regions will influence disease trends. While 70% of the population in South America is urbanized, the proportion in sub-Saharan Africa is less than 45%. Climatic anomalies associated with the El Niño-Southern Oscillation phenomenon and resulting in drought and floods are expected to increase in frequency and intensity. They have been linked to outbreaks of malaria in Africa, Asia and South America. Climate change has far-reaching consequences and touches on all life-support systems. It is therefore a factor that should be placed high among those that affect human health and survival. PMID:11019462

Addressing vulnerability, building resilience: community-based adaptation to vector-borne diseases in the context of global change.

PubMed

Bardosh, Kevin Louis; Ryan, Sadie J; Ebi, Kris; Welburn, Susan; Singer, Burton

2017-12-11

The threat of a rapidly changing planet - of coupled social, environmental and climatic change - pose new conceptual and practical challenges in responding to vector-borne diseases. These include non-linear and uncertain spatial-temporal change dynamics associated with climate, animals, land, water, food, settlement, conflict, ecology and human socio-cultural, economic and political-institutional systems. To date, research efforts have been dominated by disease modeling, which has provided limited practical advice to policymakers and practitioners in developing policies and programmes on the ground. In this paper, we provide an alternative biosocial perspective grounded in social science insights, drawing upon concepts of vulnerability, resilience, participation and community-based adaptation. Our analysis was informed by a realist review (provided in the Additional file 2) focused on seven major climate-sensitive vector-borne diseases: malaria, schistosomiasis, dengue, leishmaniasis, sleeping sickness, chagas disease, and rift valley fever. Here, we situate our analysis of existing community-based interventions within the context of global change processes and the wider social science literature. We identify and discuss best practices and conceptual principles that should guide future community-based efforts to mitigate human vulnerability to vector-borne diseases. We argue that more focused attention and investments are needed in meaningful public participation, appropriate technologies, the strengthening of health systems, sustainable development, wider institutional changes and attention to the social determinants of health, including the drivers of co-infection. In order to respond effectively to uncertain future scenarios for vector-borne disease in a changing world, more attention needs to be given to building resilient and equitable systems in the present.

Mobilizing community-based health insurance to enhance awareness & prevention of airborne, vector-borne & waterborne diseases in rural India.

PubMed

Panda, Pradeep; Chakraborty, Arpita; Dror, David M

2015-08-01

Despite remarkable progress in airborne, vector-borne and waterborne diseases in India, the morbidity associated with these diseases is still high. Many of these diseases are controllable through awareness and preventive practice. This study was an attempt to evaluate the effectiveness of a preventive care awareness campaign in enhancing knowledge related with airborne, vector-borne and waterborne diseases, carried out in 2011 in three rural communities in India (Pratapgarh and Kanpur-Dehat in Uttar Pradesh and Vaishali in Bihar). Data for this analysis were collected from two surveys, one done before the campaign and the other after it, each of 300 randomly selected households drawn from a larger sample of Self-Help Groups (SHGs) members invited to join community-based health insurance (CBHI) schemes. The results showed a significant increase both in awareness (34%, p<0.001) and in preventive practices (48%, P=0.001), suggesting that the awareness campaign was effective. However, average practice scores (0.31) were substantially lower than average awareness scores (0.47), even in post-campaign. Awareness and preventive practices were less prevalent in vector-borne diseases than in airborne and waterborne diseases. Education was positively associated with both awareness and practice scores. The awareness scores were positive and significant determinants of the practice scores, both in the pre- and in the post-campaign results. Affiliation to CBHI had significant positive influence on awareness and on practice scores in the post-campaign period. The results suggest that well-crafted health educational campaigns can be effective in raising awareness and promoting health-enhancing practices in resource-poor settings. It also confirms that CBHI can serve as a platform to enhance awareness to risks of exposure to airborne, vector-borne and waterborne diseases, and encourage preventive practices.

Comparison of serological and molecular panels for diagnosis of vector-borne diseases in dogs

PubMed Central

2014-01-01

Background Canine vector-borne diseases (CVBD) are caused by a diverse array of pathogens with varying biological behaviors that result in a wide spectrum of clinical presentations and laboratory abnormalities. For many reasons, the diagnosis of canine vector-borne infectious diseases can be challenging for clinicians. The aim of the present study was to compare CVBD serological and molecular testing as the two most common methodologies used for screening healthy dogs or diagnosing sick dogs in which a vector-borne disease is suspected. Methods We used serological (Anaplasma species, Babesia canis, Bartonella henselae, Bartonella vinsonii subspecies berkhoffii, Borrelia burgdorferi, Ehrlichia canis, and SFG Rickettsia) and molecular assays to assess for exposure to, or infection with, 10 genera of organisms that cause CVBDs (Anaplasma, Babesia, Bartonella, Borrelia, Ehrlichia, Francisella, hemotropic Mycoplasma, Neorickettsia, Rickettsia, and Dirofilaria). Paired serum and EDTA blood samples from 30 clinically healthy dogs (Group I) and from 69 sick dogs suspected of having one or more canine vector-borne diseases (Groups II-IV), were tested in parallel to establish exposure to or infection with the specific CVBDs targeted in this study. Results Among all dogs tested (Groups I-IV), the molecular prevalences for individual CVBD pathogens ranged between 23.3 and 39.1%. Similarly, pathogen-specific seroprevalences ranged from 43.3% to 59.4% among healthy and sick dogs (Groups I-IV). Among these representative sample groupings, a panel combining serological and molecular assays run in parallel resulted in a 4-58% increase in the recognition of exposure to or infection with CVBD. Conclusions We conclude that serological and PCR assays should be used in parallel to maximize CVBD diagnosis. PMID:24670154

Spatially explicit multi-criteria decision analysis for managing vector-borne diseases

PubMed Central

2011-01-01

The complex epidemiology of vector-borne diseases creates significant challenges in the design and delivery of prevention and control strategies, especially in light of rapid social and environmental changes. Spatial models for predicting disease risk based on environmental factors such as climate and landscape have been developed for a number of important vector-borne diseases. The resulting risk maps have proven value for highlighting areas for targeting public health programs. However, these methods generally only offer technical information on the spatial distribution of disease risk itself, which may be incomplete for making decisions in a complex situation. In prioritizing surveillance and intervention strategies, decision-makers often also need to consider spatially explicit information on other important dimensions, such as the regional specificity of public acceptance, population vulnerability, resource availability, intervention effectiveness, and land use. There is a need for a unified strategy for supporting public health decision making that integrates available data for assessing spatially explicit disease risk, with other criteria, to implement effective prevention and control strategies. Multi-criteria decision analysis (MCDA) is a decision support tool that allows for the consideration of diverse quantitative and qualitative criteria using both data-driven and qualitative indicators for evaluating alternative strategies with transparency and stakeholder participation. Here we propose a MCDA-based approach to the development of geospatial models and spatially explicit decision support tools for the management of vector-borne diseases. We describe the conceptual framework that MCDA offers as well as technical considerations, approaches to implementation and expected outcomes. We conclude that MCDA is a powerful tool that offers tremendous potential for use in public health decision-making in general and vector-borne disease management in particular. PMID:22206355

Comparison of serological and molecular panels for diagnosis of vector-borne diseases in dogs.

PubMed

Maggi, Ricardo G; Birkenheuer, Adam J; Hegarty, Barbara C; Bradley, Julie M; Levy, Michael G; Breitschwerdt, Edward B

2014-03-26

Canine vector-borne diseases (CVBD) are caused by a diverse array of pathogens with varying biological behaviors that result in a wide spectrum of clinical presentations and laboratory abnormalities. For many reasons, the diagnosis of canine vector-borne infectious diseases can be challenging for clinicians. The aim of the present study was to compare CVBD serological and molecular testing as the two most common methodologies used for screening healthy dogs or diagnosing sick dogs in which a vector-borne disease is suspected. We used serological (Anaplasma species, Babesia canis, Bartonella henselae, Bartonella vinsonii subspecies berkhoffii, Borrelia burgdorferi, Ehrlichia canis, and SFG Rickettsia) and molecular assays to assess for exposure to, or infection with, 10 genera of organisms that cause CVBDs (Anaplasma, Babesia, Bartonella, Borrelia, Ehrlichia, Francisella, hemotropic Mycoplasma, Neorickettsia, Rickettsia, and Dirofilaria). Paired serum and EDTA blood samples from 30 clinically healthy dogs (Group I) and from 69 sick dogs suspected of having one or more canine vector-borne diseases (Groups II-IV), were tested in parallel to establish exposure to or infection with the specific CVBDs targeted in this study. Among all dogs tested (Groups I-IV), the molecular prevalences for individual CVBD pathogens ranged between 23.3 and 39.1%. Similarly, pathogen-specific seroprevalences ranged from 43.3% to 59.4% among healthy and sick dogs (Groups I-IV). Among these representative sample groupings, a panel combining serological and molecular assays run in parallel resulted in a 4-58% increase in the recognition of exposure to or infection with CVBD. We conclude that serological and PCR assays should be used in parallel to maximize CVBD diagnosis.

Cytopathogenesis of Vesicular Stomatitis virus is regulated by the PSAP motif of M protein in a species-dependent manner

USDA-ARS?s Scientific Manuscript database

Vesicular stomatitis virus (VSV) is an important vector-borne pathogen of bovine and equine species, causing a reportable vesicular disease. The matrix (M) protein of VSV is multifunctional and plays a key role in cytopathogenesis, apoptosis, host protein shut-off, and virion assembly/budding. Our ...

Potential impact of climate change on emerging vector-borne and other infections in the UK.

PubMed

Baylis, Matthew

2017-12-05

Climate is one of several causes of disease emergence. Although half or more of infectious diseases are affected by climate it appears to be a relatively infrequent cause of human disease emergence. Climate mostly affects diseases caused by pathogens that spend part of their lifecycle outside of the host, exposed to the environment. The most important routes of transmission of climate sensitive diseases are by arthropod (insect and tick) vectors, in water and in food. Given the sensitivity of many diseases to climate, it is very likely that at least some will respond to future climate change. In the case of vector-borne diseases this response will include spread to new areas. Several vector-borne diseases have emerged in Europe in recent years; these include vivax malaria, West Nile fever, dengue fever, Chikungunya fever, leishmaniasis, Lyme disease and tick-borne encephalitis. The vectors of these diseases are mosquitoes, sand flies and ticks. The UK has endemic mosquito species capable of transmitting malaria and probably other pathogens, and ticks that transmit Lyme disease. The UK is also threatened by invasive mosquito species known to be able to transmit West Nile, dengue, chikungunya and Zika, and sand flies that spread leishmaniasis. Warmer temperatures in the future will increase the suitability of the UK's climate for these invasive species, and increase the risk that they may spread disease. While much attention is on invasive species, it is important to recognize the threat presented by native species too. Proposed actions to reduce the future impact of emerging vector-borne diseases in the UK include insect control activity at points of entry of vehicles and certain goods, wider surveillance for mosquitoes and sand flies, research into the threat posed by native species, increased awareness of the medical profession of the threat posed by specific diseases, regular risk assessments, and increased preparedness for the occurrence of a disease emergency.

The role of viral persistence in flavivirus biology

PubMed Central

Mlera, Luwanika; Melik, Wessam; Bloom, Marshall E.

2014-01-01

In nature, vector-borne flaviviruses are persistently cycled between either the tick or mosquito vector and small mammals such as rodents, skunks, and swine. These viruses account for considerable human morbidity and mortality worldwide. Increasing and substantial evidence of viral persistence in humans, which includes the isolation of RNA by RT-PCR and infectious virus by culture, continues to be reported. Viral persistence can also be established in vitro in various human, animal, arachnid and insect cell lines in culture. Although some research has focused on the potential roles of defective virus particles, evasion of the immune response through the manipulation of autophagy and/or apoptosis, the precise mechanism of flavivirus persistence is still not well understood. We propose additional research for further understanding of how viral persistence is established in different systems. Avenues for additional studies include determining if the multifunctional flavivirus protein NS5 has a role in viral persistence, the development of relevant animal models of viral persistence as well as investigating the host responses that allow vector borne flavivirus replication without detrimental effects on infected cells. Such studies might shed more light on the viral-host relationships, and could be used to unravel the mechanisms for establishment of persistence. PMID:24737600

Molecular epidemiological survey and genetic analysis of vector-borne infections of cattle in Luzon Island, the Philippines.

PubMed

Ochirkhuu, Nyamsuren; Konnai, Satoru; Mingala, Claro N; Okagawa, Tomohiro; Villanueva, Marvin; Pilapil, Flor Marie Immanuelle R; Murata, Shiro; Ohashi, Kazuhiko

2015-09-15

In the Philippines, vector-borne disease is one of the important problems in the livestock industry. To elucidate the epidemiology of vector-borne diseases in cattle on Luzon Island, the Philippines, the prevalence of five protozoan agents was assessed by polymerase chain reaction. Out of the 339 samples, 324 (95.5%), 154 (45.4%), 209 (61.6%), 140 (41.3%), and 2 (0.6%) were positive for Anaplasma marginale, Babesia bigemina, Babesia bovis, Theileria spp., and Trypanosoma evansi infections, respectively. Mixed infections were detected in 290 (85.5%) samples, of which 115 (33.9%) had two pathogens, 144 (42.5%) had three pathogens, and 31 (9.1%) had four kinds of pathogens. 16S rRNA gene was 100% identical in A. marginale compared with the same lineage across the world. B. bovis RAP-1 and B. bigemina AMA-1 genes were identical with 92.27%-100% and 97.07%-100% sequences, respectively, in the database (Asian isolates). MPSP genes of Theileria spp. were 83.51%-100% identical with the one another. Phylogenetic analysis showed that they belong to the groups of T. sergenti and T. buffeli. Positive rates of the tick-borne pathogens were extremely high in this area. These findings provide vital information that can be used for the planning and execution of effective control measures for vector-borne diseases in the Philippine cattle industry. Copyright © 2015 Elsevier B.V. All rights reserved.

Multistrain Infections with Lyme Borreliosis Pathogens in the Tick Vector.

PubMed

Durand, Jonas; Herrmann, Coralie; Genné, Dolores; Sarr, Anouk; Gern, Lise; Voordouw, Maarten J

2017-02-01

Mixed or multiple-strain infections are common in vector-borne diseases and have important implications for the epidemiology of these pathogens. Previous studies have mainly focused on interactions between pathogen strains in the vertebrate host, but little is known about what happens in the arthropod vector. Borrelia afzelii and Borrelia garinii are two species of spirochete bacteria that cause Lyme borreliosis in Europe and that share a tick vector, Ixodes ricinus Each of these two tick-borne pathogens consists of multiple strains that are often differentiated using the highly polymorphic ospC gene. For each Borrelia species, we studied the frequencies and abundances of the ospC strains in a wild population of I. ricinus ticks that had been sampled from the same field site over a period of 3 years. We used quantitative PCR (qPCR) and 454 sequencing to estimate the spirochete load and the strain diversity within each tick. For B. afzelii, there was a negative relationship between the two most common ospC strains, suggesting the presence of competitive interactions in the vertebrate host and possibly the tick vector. The flat relationship between total spirochete abundance and strain richness in the nymphal tick indicates that the mean abundance per strain decreases as the number of strains in the tick increases. Strains with the highest spirochete load in the nymphal tick were the most common strains in the tick population. The spirochete abundance in the nymphal tick appears to be an important life history trait that explains why some strains are more common than others in nature. Lyme borreliosis is the most common vector-borne disease in the Northern Hemisphere and is caused by spirochete bacteria that belong to the Borrelia burgdorferi sensu lato species complex. These tick-borne pathogens are transmitted among vertebrate hosts by hard ticks of the genus Ixodes Each Borrelia species can be further subdivided into genetically distinct strains. Multiple-strain infections are common in both the vertebrate host and the tick vector and can result in competitive interactions. To date, few studies on multiple-strain vector-borne pathogens have investigated patterns of cooccurrence and abundance in the arthropod vector. We demonstrate that the abundance of a given strain in the tick vector is negatively affected by the presence of coinfecting strains. In addition, our study suggests that the spirochete abundance in the tick is an important life history trait that can explain why some strains are more common in nature than others. Copyright © 2017 American Society for Microbiology.

Recent Weather Extremes and Impacts on Agricultural Production and Vector-Borne Disease Outbreak Patterns

DTIC Science & Technology

2014-03-21

funding from USDA Foreign Agricultural Service towards the Global Agricultural Monitoring project, DoD Armed Forces Health Surveillance Center’s...Global Emerging Infections Surveillance and Response System (AFHSC/GEIS) under the Human Febrile and Vector -Borne Illnesses (FVBI) Program and USDA ...outbreaks during the 2010?2012 period. We utilized 2000?2012 vegetation index and land surface temperature data from NASA ?s satellitebased Moderate

Pentatomoids as vectors of plant pathogens

USDA-ARS?s Scientific Manuscript database

Vector-borne pathogens can be categorized functionally according to the degree of symbiosis that they acquire with their respective vectors. Three modes of transmission have been broadly described: non-persistent, semi-persistent, and persistent. Originally compiled specifically for viruses transm...

Climate Change and Vector Borne Diseases on NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Cole, Stuart K.; DeYoung, Russell J.; Shepanek, Marc A.; Kamel, Ahmed

2014-01-01

Increasing global temperature, weather patterns with above average storm intensities, and higher sea levels have been identified as phenomena associated with global climate change. As a causal system, climate change could contribute to vector borne diseases in humans. Vectors of concern originate from the vicinity of Langley Research Center include mosquitos and ticks that transmit disease that originate regionally, nationwide, or from outside the US. Recognizing changing conditions, vector borne diseases propagate under climate change conditions, and understanding the conditions in which they may exist or propagate, presents opportunities for monitoring their progress and mitigating their potential impacts through communication, continued monitoring, and adaptation. Personnel comprise a direct and fundamental support to NASA mission success, continuous and improved understanding of climatic conditions, and the resulting consequence of disease from these conditions, helps to reduce risk in terrestrial space technologies, ground operations, and space research. This research addresses conditions which are attributed to climatic conditions which promote environmental conditions conducive to the increase of disease vectors. This investigation includes evaluation of local mosquito population count and rainfall data for statistical correlation and identification of planning recommendations unique to LaRC, other NASA Centers to assess adaptation approaches, Center-level planning strategies.

Epidemiological Implications of Host Biodiversity and Vector Biology: Key Insights from Simple Models.

PubMed

Dobson, Andrew D M; Auld, Stuart K J R

2016-04-01

Models used to investigate the relationship between biodiversity change and vector-borne disease risk often do not explicitly include the vector; they instead rely on a frequency-dependent transmission function to represent vector dynamics. However, differences between classes of vector (e.g., ticks and insects) can cause discrepancies in epidemiological responses to environmental change. Using a pair of disease models (mosquito- and tick-borne), we simulated substitutive and additive biodiversity change (where noncompetent hosts replaced or were added to competent hosts, respectively), while considering different relationships between vector and host densities. We found important differences between classes of vector, including an increased likelihood of amplified disease risk under additive biodiversity change in mosquito models, driven by higher vector biting rates. We also draw attention to more general phenomena, such as a negative relationship between initial infection prevalence in vectors and likelihood of dilution, and the potential for a rise in density of infected vectors to occur simultaneously with a decline in proportion of infected hosts. This has important implications; the density of infected vectors is the most valid metric for primarily zoonotic infections, while the proportion of infected hosts is more relevant for infections where humans are a primary host.

Natural Mosquito-Pathogen Hybrid IgG4 Antibodies in Vector-Borne Diseases: A Hypothesis.

PubMed

Londono-Renteria, Berlin; Cardenas, Jenny C; Troupin, Andrea; Colpitts, Tonya M

2016-01-01

Chronic exposure to antigens may favor the production of IgG4 antibodies over other antibody types. Recent studies have shown that up to a 30% of normal human IgG4 is bi-specific and is able to recognize two antigens of different nature. A requirement for this specificity is the presence of both eliciting antigens in the same time and at the same place where the immune response is induced. During transmission of most vector-borne diseases, the pathogen is delivered to the vertebrate host along with the arthropod saliva during blood feeding and previous studies have shown the existence of IgG4 antibodies against mosquito salivary allergens. However, there is very little ongoing research or information available regarding IgG4 bi-specificity with regard to infectious disease, particularly during immune responses to vector-borne diseases, such as malaria, filariasis, or dengue virus infection. Here, we provide background information and present our hypothesis that IgG4 may not only be a useful tool to measure exposure to infected mosquito bites, but that these bi-specific antibodies may also play an important role in modulation of the immune response against malaria and other vector-borne diseases in endemic settings.

Pangloss revisited: a critique of the dilution effect and the biodiversity-buffers-disease paradigm.

PubMed

Randolph, S E; Dobson, A D M

2012-06-01

The twin concepts of zooprophylaxis and the dilution effect originated with vector-borne diseases (malaria), were driven forward by studies on Lyme borreliosis and have now developed into the mantra "biodiversity protects against disease". The basic idea is that by diluting the assemblage of transmission-competent hosts with non-competent hosts, the probability of vectors feeding on transmission-competent hosts is reduced and so the abundance of infected vectors is lowered. The same principle has recently been applied to other infectious disease systems--tick-borne, insect-borne, indirectly transmitted via intermediate hosts, directly transmitted. It is claimed that the presence of extra species of various sorts, acting through a variety of distinct mechanisms, causes the prevalence of infectious agents to decrease. Examination of the theoretical and empirical evidence for this hypothesis reveals that it applies only in certain circumstances even amongst tick-borne diseases, and even less often if considering the correct metric--abundance rather than prevalence of infected vectors. Whether dilution or amplification occurs depends more on specific community composition than on biodiversity per se. We warn against raising a straw man, an untenable argument easily dismantled and dismissed. The intrinsic value of protecting biodiversity and ecosystem function outweighs this questionable utilitarian justification.

Efficacy of Plant-Derived and Synthetic Compounds on Clothing as Repellents Against Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae)

DTIC Science & Technology

2012-01-01

concern (Gratz 1999). Lyme disease, caused by the spirocheteBorrelia burgdorferi, is themost commonly reported vector-borne disease in the United States...and the incidence of Lyme disease continues to in- crease. In the past 5 yr, an average of 20,000 cases have been reported annually, whereas the...number of reported Lyme disease cases reached an all-time high of35,000 in 2008 (CDC 2010). The blacklegged tick, Ixodes scapularis Say, the principal

The Interaction between Vector Life History and Short Vector Life in Vector-Borne Disease Transmission and Control.

PubMed

Brand, Samuel P C; Rock, Kat S; Keeling, Matt J

2016-04-01

Epidemiological modelling has a vital role to play in policy planning and prediction for the control of vectors, and hence the subsequent control of vector-borne diseases. To decide between competing policies requires models that can generate accurate predictions, which in turn requires accurate knowledge of vector natural histories. Here we highlight the importance of the distribution of times between life-history events, using short-lived midge species as an example. In particular we focus on the distribution of the extrinsic incubation period (EIP) which determines the time between infection and becoming infectious, and the distribution of the length of the gonotrophic cycle which determines the time between successful bites. We show how different assumptions for these periods can radically change the basic reproductive ratio (R0) of an infection and additionally the impact of vector control on the infection. These findings highlight the need for detailed entomological data, based on laboratory experiments and field data, to correctly construct the next-generation of policy-informing models.

The quest for a non-vector psyllid: Natural variation in acquisition and transmission of the huanglongbing pathogen 'Candidatus Liberibacter asiaticus' by Asian citrus psyllid isofemale lines

USDA-ARS?s Scientific Manuscript database

Genetic variability in insect vectors is valuable to study vector competence determinants and to select non-vector populations that may help reduce the spread of vector-borne pathogens. We collected and tested vector competency of 15 isofemale lines of Asian citrus psyllid (ACP) Diaphorina citri, v...

Launching the first postgraduate diploma in medical entomology and disease vector control in Pakistan.

PubMed

Rathor, H R; Mnzava, A; Bile, K M; Hafeez, A; Zaman, S

2010-01-01

The Health Services Academy has launched a 12-month postgraduate diploma course in medical entomology and disease vector control. The objective is to create a core of experts trained to prevent and control vector-borne diseases. The course is a response to the serious health and socioeconomic burden caused by a number of vector-borne diseases in Pakistan. The persistence, emergence and re-emergence of these diseases is mainly attributed to the scarcity of trained vector-control experts. The training course attempts to fill the gap in trained manpower and thus reduce the morbidity and mortality due to these diseases, resulting in incremental gains to public health. This paper aims to outline the steps taken to establish the course and the perceived challenges to be addressed in order to sustain its future implementation.

Transmission of tick-borne pathogens between co-feeding ticks: Milan Labuda's enduring paradigm.

PubMed

Randolph, Sarah E

2011-12-01

During the 1990s, Milan Labuda's experimental results established a new paradigm for the study of tick-borne viruses that has since been strengthened by its demonstrated effectiveness in explaining the epidemiology of tick-borne encephalitis (TBE). This brief review summarizes the essential features of the transmission of tick-borne pathogens such as TBE virus. Leukocytes migrate between tick feeding sites, bearing infective virions and providing a transport route for the virus between co-feeding ticks independent of a systemic viraemia. Such tick-borne pathogens are thus transmitted from tick to tick via vertebrates; the ticks are the reservoirs as well as the vectors, while the vertebrate is the transient bridge. The aim is to bring the related but non-synonymous terms (co-feeding and non-systemic) to the attention of workers who use simple PCR screening to identify additional vertebrate reservoir hosts of vector-borne pathogens that are not in fact maintained in nature through systemic transmission. Copyright © 2011 Elsevier GmbH. All rights reserved.

System Dynamics based Dengue modeling environment to simulate evolution of Dengue infection under different climate scenarios

NASA Astrophysics Data System (ADS)

Anwar, R.; Khan, R.; Usmani, M.; Colwell, R. R.; Jutla, A.

2017-12-01

Vector borne infectious diseases such as Dengue, Zika and Chikungunya remain a public health threat. An estimate of the World Health Organization (WHO) suggests that about 2.5 billion people, representing ca. 40% of human population,are at increased risk of dengue; with more than 100 million infection cases every year. Vector-borne infections cannot be eradicated since disease causing pathogens survive in the environment. Over the last few decades dengue infection has been reported in more than 100 countries and is expanding geographically. Female Ae. Aegypti mosquito, the daytime active and a major vector for dengue virus, is associated with urban population density and regional climatic processes. However, mathematical quantification of relationships on abundance of vectors and climatic processes remain a challenge, particularly in regions where such data are not routinely collected. Here, using system dynamics based feedback mechanism, an algorithm integrating knowledge from entomological, meteorological and epidemiological processes is developed that has potential to provide ensemble simulations on risk of occurrence of dengue infection in human population. Using dataset from satellite remote sensing, the algorithm was calibrated and validated using actual dengue case data of Iquitos, Peru. We will show results on model capabilities in capturing initiation and peak in the observed time series. In addition, results from several simulation scenarios under different climatic conditions will be discussed.

Peridomestic Aedes malayensis and Aedes albopictus are capable vectors of arboviruses in cities

PubMed Central

Manuel, Menchie; Low, Dolyce H. W.; Missé, Dorothée; Gubler, Duane J.; Ellis, Brett R.; Ooi, Eng Eong; Pompon, Julien

2017-01-01

Background Dengue and chikungunya are global re-emerging mosquito-borne diseases. In Singapore, sustained vector control coupled with household improvements reduced domestic mosquito populations for the past 45 years, particularly the primary vector Aedes aegypti. However, while disease incidence was low for the first 30 years following vector control implementation, outbreaks have re-emerged in the past 15 years. Epidemiological observations point to the importance of peridomestic infection in areas not targeted by control programs. We investigated the role of vectors in peri-domestic areas. Methods We carried out entomological surveys to identify the Aedes species present in vegetated sites in highly populated areas and determine whether mosquitoes were present in open-air areas frequented by people. We compared vector competence of Aedes albopictus and Aedes malayensis with Ae. aegypti after oral infection with sympatric dengue serotype 2 and chikungunya viruses. Mosquito saliva was tested for the presence of infectious virus particles as a surrogate for transmission following oral infection. Results We identified Aedes albopictus and Aedes malayensis throughout Singapore and quantified their presence in forested and opened grassy areas. Both Ae. albopictus and Ae. malayensis can occupy sylvatic niches and were highly susceptible to both arboviruses. A majority of saliva of infected Ae. malayensis contained infectious particles for both viruses. Conclusions Our study reveals the prevalence of competent vectors in peri-domestic areas, including Ae. malayensis for which we established the vector status. Epidemics can be driven by infection foci, which are epidemiologically enhanced in the context of low herd immunity, selective pressure on arbovirus transmission and the presence of infectious asymptomatic persons, all these conditions being present in Singapore. Learning from Singapore’s vector control success that reduced domestic vector populations, but has not sustainably reduced arboviral incidence, we suggest including peri-domestic vectors in the scope of vector management. PMID:28650959

Ectoparasites of Microtus californicus and Possible Emergence of an Exotic Ixodes Species Tick in California.

PubMed

Poulsen, Amanda; Conroy, Chris; Foley, Patrick; Ott-Conn, Caitlin; Roy, Austin; Brown, Richard; Foley, Janet

2015-09-01

California voles (Microtus californicus Peale) harbor fleas and ticks, may be infected with vector-borne pathogens, and could themselves suffer from disease and serve as a source of infection for people and other animals. Here we summarize publications, museum archives, and recent records of ticks and fleas from California voles. There have been 18 flea species reported on California voles with geographic locations reported for 13. During recent statewide surveys, we found six flea species, with the highest species richness in Humboldt County. We found three of five previously reported tick species as well as a tick resembling the eastern North American tick Ixodes minor Neumann (which we here designate Ixodes "Mojave morphotype") on isolated Amargosa voles and Owens Valley voles (Microtus californicus vallicola Bailey) in Inyo County in 2012 and 2014. Additional incidental observations of this Mojave morphotype tick were on a western harvest mouse (Reithrodontomys megalotis Baird) at the Mojave site and a montane vole (Microtus montanus Peale) in the Owens Valley, both in March, 2014. We cannot rule out that this tick species has been present in remote areas of California but gone unrecognized, but these data are consistent with recent introduction of this tick, possibly from migrating birds. Changes in the ectoparasite fauna suggest changing ecologies of vectors and vector-borne pathogens that could influence animals and people as well. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Modelling the spatial distribution of the nuisance mosquito species Anopheles plumbeus (Diptera: Culicidae) in the Netherlands.

PubMed

Ibañez-Justicia, Adolfo; Cianci, Daniela

2015-05-01

Landscape modifications, urbanization or changes of use of rural-agricultural areas can create more favourable conditions for certain mosquito species and therefore indirectly cause nuisance problems for humans. This could potentially result in mosquito-borne disease outbreaks when the nuisance is caused by mosquito species that can transmit pathogens. Anopheles plumbeus is a nuisance mosquito species and a potential malaria vector. It is one of the most frequently observed species in the Netherlands. Information on the distribution of this species is essential for risk assessments. The purpose of the study was to investigate the potential spatial distribution of An. plumbeus in the Netherlands. Random forest models were used to link the occurrence and the abundance of An. plumbeus with environmental features and to produce distribution maps in the Netherlands. Mosquito data were collected using a cross-sectional study design in the Netherlands, from April to October 2010-2013. The environmental data were obtained from satellite imagery and weather stations. Statistical measures (accuracy for the occurrence model and mean squared error for the abundance model) were used to evaluate the models performance. The models were externally validated. The maps show that forested areas (centre of the Netherlands) and the east of the country were predicted as suitable for An. plumbeus. In particular high suitability and high abundance was predicted in the south-eastern provinces Limburg and North Brabant. Elevation, precipitation, day and night temperature and vegetation indices were important predictors for calculating the probability of occurrence for An. plumbeus. The probability of occurrence, vegetation indices and precipitation were important for predicting its abundance. The AUC value was 0.73 and the error in the validation was 0.29; the mean squared error value was 0.12. The areas identified by the model as suitable and with high abundance of An. plumbeus, are consistent with the areas from which nuisance was reported. Our results can be helpful in the assessment of vector-borne disease risk.

Current Knowledge of Leishmania Vectors in Mexico: How Geographic Distributions of Species Relate to Transmission Areas

PubMed Central

González, Camila; Rebollar-Téllez, Eduardo A.; Ibáñez-Bernal, Sergio; Becker-Fauser, Ingeborg; Martínez-Meyer, Enrique; Peterson, A. Townsend; Sánchez-Cordero, Víctor

2011-01-01

Leishmaniases are a group of vector-borne diseases with different clinical manifestations caused by parasites transmitted by sand fly vectors. In Mexico, the sand fly Lutzomyia olmeca olmeca is the only vector proven to transmit the parasite Leishmania mexicana to humans, which causes leishmaniasis. Other vector species with potential medical importance have been obtained, but their geographic distributions and relation to transmission areas have never been assessed. We modeled the ecological niches of nine sand fly species and projected niches to estimate potential distributions by using known occurrences, environmental coverages, and the algorithms GARP and Maxent. All vector species were distributed in areas with known recurrent transmission, except for Lu. diabolica, which appeared to be related only to areas of occasional transmission in northern Mexico. The distribution of Lu. o. olmeca does not overlap with all reported cutaneous leishmaniasis cases, suggesting that Lu. cruciata and Lu. shannoni are likely also involved as primary vectors in those areas. Our study provides useful information of potential risk areas of leishmaniasis transmission in Mexico. PMID:22049037

Emerging Tick-Borne Viruses in the Twenty-First Century

PubMed Central

Mansfield, Karen L.; Jizhou, Lv; Phipps, L. Paul; Johnson, Nicholas

2017-01-01

Ticks, as a group, are second only to mosquitoes as vectors of pathogens to humans and are the primary vector for pathogens of livestock, companion animals, and wildlife. The role of ticks in the transmission of viruses has been known for over 100 years and yet new pathogenic viruses are still being detected and known viruses are continually spreading to new geographic locations. Partly as a result of their novelty, tick-virus interactions are at an early stage in understanding. For some viruses, even the principal tick-vector is not known. It is likely that tick-borne viruses will continue to emerge and challenge public and veterinary health long into the twenty-first century. However, studies focusing on tick saliva, a critical component of tick feeding, virus transmission, and a target for control of ticks and tick-borne diseases, point toward solutions to emerging viruses. The aim of this review is to describe some currently emerging tick-borne diseases, their causative viruses, and to discuss research on virus-tick interactions. Through focus on this area, future protein targets for intervention and vaccine development may be identified. PMID:28744449

The impact of dissociation on transposon-mediated disease control strategies.

PubMed

Marshall, John M

2008-03-01

Vector-borne diseases such as malaria and dengue fever continue to be a major health concern through much of the world. The emergence of chloroquine-resistant strains of malaria and insecticide-resistant mosquitoes emphasize the need for novel methods of disease control. Recently, there has been much interest in the use of transposable elements to drive resistance genes into vector populations as a means of disease control. One concern that must be addressed before a release is performed is the potential loss of linkage between a transposable element and a resistance gene. Transposable elements such as P and hobo have been shown to produce internal deletion derivatives at a significant rate, and there is concern that a similar process could lead to loss of the resistance gene from the drive system following a transgenic release. Additionally, transposable elements such as Himar1 have been shown to transpose significantly more frequently when free of exogenous DNA. Here, we show that any transposon-mediated gene drive strategy must have an exceptionally low rate of dissociation if it is to be effective. Additionally, the resistance gene must confer a large selective advantage to the vector to surmount the effects of a moderate dissociation rate and transpositional handicap.

Plasmodium vivax malaria in a Romanian traveller returning from Greece, August 2011.

PubMed

Florescu, S A; Popescu, C P; Calistru, P; Ceausu, E; Nica, M; Toderan, A; Zaharia, M; Parola, P

2011-09-01

In August 2011, a Plasmodium vivax malaria infection was diagnosed in a Romanian traveller returning from Greece. This case together with several reports over the past decade of autochthonous cases in Greece highlight that malaria should be considered as differential diagnosis in symptomatic travellers returning from this country. Travellers may serve as sentinels of emerging vector-borne diseases.

Vector-borne diseases in cats in Germany.

PubMed

Bergmann, Michèle; Hartmann, Katrin

2017-10-17

Vector-borne diseases (VBDs) are caused by a wide range of pathogens, which are transmitted by a variety of vectors, such as ticks and fleas. As a result of climate changes, more vector-borne diseases are becoming endemic in Germany, not only in dogs, but also in cats. For some of the pathogens prevalence data still need to be investigated in Germany. However, natural infections with Bartonella, Anaplasma, haemotropic Mycoplasma and Borrelia species have already been described in German cats. Clinical relevance of these pathogens is not fully understood, and it is still unknown, why most infected cats stay asymptomatic and which predisposing factors contribute to the development of clinical signs in cats. Moreover, there is a risk of zoonotic transmission for some of the pathogens, e.  g., for some Bartonella spp. infections that are associated with cat scratch disease in humans. Due to the increasing number of VBDs in cats in Germany, preventive measures, such as the use of acaricides and insecticides, should be performed on a regular base in order to reduce the risk of these infections.

9 CFR 92.1 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... and possessions of the United States. Vector-borne disease. A disease transmitted to an animal through... or capable of being carriers of those diseases or their arthropod vectors. Communicable disease. Any... susceptible animal from an infected animal, vector, inanimate source, or other sources. Contagious disease...

The status of tularemia in Europe in a one-health context: a review.

PubMed

Hestvik, G; Warns-Petit, E; Smith, L A; Fox, N J; Uhlhorn, H; Artois, M; Hannant, D; Hutchings, M R; Mattsson, R; Yon, L; Gavier-Widen, D

2015-07-01

The bacterium Francisella tularensis causes the vector-borne zoonotic disease tularemia, and may infect a wide range of hosts including invertebrates, mammals and birds. Transmission to humans occurs through contact with infected animals or contaminated environments, or through arthropod vectors. Tularemia has a broad geographical distribution, and there is evidence which suggests local emergence or re-emergence of this disease in Europe. This review was developed to provide an update on the geographical distribution of F. tularensis in humans, wildlife, domestic animals and vector species, to identify potential public health hazards, and to characterize the epidemiology of tularemia in Europe. Information was collated on cases in humans, domestic animals and wildlife, and on reports of detection of the bacterium in arthropod vectors, from 38 European countries for the period 1992-2012. Multiple international databases on human and animal health were consulted, as well as published reports in the literature. Tularemia is a disease of complex epidemiology that is challenging to understand and therefore to control. Many aspects of this disease remain poorly understood. Better understanding is needed of the epidemiological role of animal hosts, potential vectors, mechanisms of maintenance in the different ecosystems, and routes of transmission of the disease.

Mathematical modelling of vector-borne diseases and insecticide resistance evolution.

PubMed

Gabriel Kuniyoshi, Maria Laura; Pio Dos Santos, Fernando Luiz

2017-01-01

Vector-borne diseases are important public health issues and, consequently, in silico models that simulate them can be useful. The susceptible-infected-recovered (SIR) model simulates the population dynamics of an epidemic and can be easily adapted to vector-borne diseases, whereas the Hardy-Weinberg model simulates allele frequencies and can be used to study insecticide resistance evolution. The aim of the present study is to develop a coupled system that unifies both models, therefore enabling the analysis of the effects of vector population genetics on the population dynamics of an epidemic. Our model consists of an ordinary differential equation system. We considered the populations of susceptible, infected and recovered humans, as well as susceptible and infected vectors. Concerning these vectors, we considered a pair of alleles, with complete dominance interaction that determined the rate of mortality induced by insecticides. Thus, we were able to separate the vectors according to the genotype. We performed three numerical simulations of the model. In simulation one, both alleles conferred the same mortality rate values, therefore there was no resistant strain. In simulations two and three, the recessive and dominant alleles, respectively, conferred a lower mortality. Our numerical results show that the genetic composition of the vector population affects the dynamics of human diseases. We found that the absolute number of vectors and the proportion of infected vectors are smaller when there is no resistant strain, whilst the ratio of infected people is larger in the presence of insecticide-resistant vectors. The dynamics observed for infected humans in all simulations has a very similar shape to real epidemiological data. The population genetics of vectors can affect epidemiological dynamics, and the presence of insecticide-resistant strains can increase the number of infected people. Based on the present results, the model is a basis for development of other models and for investigating population dynamics.

Immunization with a Novel Human type 5 Adenovirus-Vectored Vaccine Expressing the Premembrane and Envelope Proteins of Zika Virus Provides Consistent and Sterilizing Protection in Multiple Immunocompetent and Immunocompromised Animal Models.

PubMed

Guo, Qiang; Chan, Jasper Fuk-Woo; Poon, Vincent Kwok-Man; Wu, Shipo; Chan, Chris Chung-Sing; Hou, Lihua; Yip, Cyril Chik-Yan; Ren, Changpeng; Cai, Jian-Piao; Zhao, Mengsu; Zhang, Anna Jinxia; Song, Xiaohong; Chan, Kwok-Hung; Wang, Busen; Kok, Kin-Hang; Wen, Yanbo; Yuen, Kwok-Yung; Chen, Wei

2018-03-29

Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both vector-borne and non-vector-borne routes. Adenovirus-vectored vaccines represent a favorable controlling measure for the ZIKV epidemic as they have been shown to be safe, immunogenic, and rapidly generable for other emerging viral infections. Evaluations of two previously reported adenovirus-vectored ZIKV vaccines were performed using non-lethal animal models and/or non-epidemic ZIKV strain. We constructed and evaluated two human adenovirus-5-vectored vaccines containing the ZIKV premembrane-envelope(Ad5-Sig-prM-Env) and envelope(Ad5-Env) proteins, respectively, in multiple non-lethal and lethal animal models using epidemic ZIKV strains. Both vaccines elicited robust humoral and cellular immune responses in immunocompetent BALB/c mice. Dexamethasone-immunosuppressed mice vaccinated with either vaccine demonstrated robust and durable antibody responses and significantly lower blood/tissue viral loads than controls(P<0.05). Similar findings were also observed in interferon-α/β-receptor-deficient A129 mice. In both these immunocompromised animal models, Ad5-Sig-prM-Env-vaccinated mice had significantly(P<0.05) higher titers of anti-ZIKV-specific neutralizing antibody titers and lower(undetectable) viral loads than Ad5-Env-vaccinated mice. The close correlation between the neutralizing antibody titer and viral load helped to explain the better protective effect of Ad5-Sig-prM-Env than Ad5-Env. Anamnestic response was absent in Ad5-Sig-prM-Env-vaccinated A129 mice. Ad5-Sig-prM-Env provided sterilizing protection against ZIKV infection in mice.

Climate variability and change in the United States: potential impacts on vector- and rodent-borne diseases.

PubMed Central

Gubler, D J; Reiter, P; Ebi, K L; Yap, W; Nasci, R; Patz, J A

2001-01-01

Diseases such as plague, typhus, malaria, yellow fever, and dengue fever, transmitted between humans by blood-feeding arthropods, were once common in the United States. Many of these diseases are no longer present, mainly because of changes in land use, agricultural methods, residential patterns, human behavior, and vector control. However, diseases that may be transmitted to humans from wild birds or mammals (zoonoses) continue to circulate in nature in many parts of the country. Most vector-borne diseases exhibit a distinct seasonal pattern, which clearly suggests that they are weather sensitive. Rainfall, temperature, and other weather variables affect in many ways both the vectors and the pathogens they transmit. For example, high temperatures can increase or reduce survival rate, depending on the vector, its behavior, ecology, and many other factors. Thus, the probability of transmission may or may not be increased by higher temperatures. The tremendous growth in international travel increases the risk of importation of vector-borne diseases, some of which can be transmitted locally under suitable circumstances at the right time of the year. But demographic and sociologic factors also play a critical role in determining disease incidence, and it is unlikely that these diseases will cause major epidemics in the United States if the public health infrastructure is maintained and improved. PMID:11359689

MosquitoMap and the Mal-area calculator: new web tools to relate mosquito species distribution with vector borne disease

PubMed Central

2010-01-01

Background Mosquitoes are important vectors of diseases but, in spite of various mosquito faunistic surveys globally, there is a need for a spatial online database of mosquito collection data and distribution summaries. Such a resource could provide entomologists with the results of previous mosquito surveys, and vector disease control workers, preventative medicine practitioners, and health planners with information relating mosquito distribution to vector-borne disease risk. Results A web application called MosquitoMap was constructed comprising mosquito collection point data stored in an ArcGIS 9.3 Server/SQL geodatabase that includes administrative area and vector species x country lookup tables. In addition to the layer containing mosquito collection points, other map layers were made available including environmental, and vector and pathogen/disease distribution layers. An application within MosquitoMap called the Mal-area calculator (MAC) was constructed to quantify the area of overlap, for any area of interest, of vector, human, and disease distribution models. Data standards for mosquito records were developed for MosquitoMap. Conclusion MosquitoMap is a public domain web resource that maps and compares georeferenced mosquito collection points to other spatial information, in a geographical information system setting. The MAC quantifies the Mal-area, i.e. the area where it is theoretically possible for vector-borne disease transmission to occur, thus providing a useful decision tool where other disease information is limited. The Mal-area approach emphasizes the independent but cumulative contribution to disease risk of the vector species predicted present. MosquitoMap adds value to, and makes accessible, the results of past collecting efforts, as well as providing a template for other arthropod spatial databases. PMID:20167090

MosquitoMap and the Mal-area calculator: new web tools to relate mosquito species distribution with vector borne disease.

PubMed

Foley, Desmond H; Wilkerson, Richard C; Birney, Ian; Harrison, Stanley; Christensen, Jamie; Rueda, Leopoldo M

2010-02-18

Mosquitoes are important vectors of diseases but, in spite of various mosquito faunistic surveys globally, there is a need for a spatial online database of mosquito collection data and distribution summaries. Such a resource could provide entomologists with the results of previous mosquito surveys, and vector disease control workers, preventative medicine practitioners, and health planners with information relating mosquito distribution to vector-borne disease risk. A web application called MosquitoMap was constructed comprising mosquito collection point data stored in an ArcGIS 9.3 Server/SQL geodatabase that includes administrative area and vector species x country lookup tables. In addition to the layer containing mosquito collection points, other map layers were made available including environmental, and vector and pathogen/disease distribution layers. An application within MosquitoMap called the Mal-area calculator (MAC) was constructed to quantify the area of overlap, for any area of interest, of vector, human, and disease distribution models. Data standards for mosquito records were developed for MosquitoMap. MosquitoMap is a public domain web resource that maps and compares georeferenced mosquito collection points to other spatial information, in a geographical information system setting. The MAC quantifies the Mal-area, i.e. the area where it is theoretically possible for vector-borne disease transmission to occur, thus providing a useful decision tool where other disease information is limited. The Mal-area approach emphasizes the independent but cumulative contribution to disease risk of the vector species predicted present. MosquitoMap adds value to, and makes accessible, the results of past collecting efforts, as well as providing a template for other arthropod spatial databases.

Features of Brazilian spotted fever in two different endemic areas in Brazil.

PubMed

Angerami, Rodrigo N; Câmara, Milena; Pacola, Márcia R; Rezende, Regina C M; Duarte, Raquel M R; Nascimento, Elvira M M; Colombo, Silvia; Santos, Fabiana C P; Leite, Ruth M; Katz, Gizelda; Silva, Luiz J

2012-12-01

Brazilian spotted fever (BSF) caused by Rickettsia rickettsii is the most important rickettsiosis and the only reportable tick-borne disease in Brazil. In Brazil, the hard tick Amblyomma cajennense is the most important BSF vector; however, in São Paulo State, A. aureolatum was also recognized as a vector species in remaining Atlantic forest areas near the metropolitan area of São Paulo city. We analyzed clinical and epidemiological features of BSF cases from two distinct areas where A. cajennense (Area 1) and A. aureolatum (Area 2) are the incriminated vectors. The clinical features demonstrate the same severity pattern of BSF in both endemic areas. Differences in seasonality, patient characteristics (median age and gender), and epidemiological risk factors (animals host contact and vegetation characteristics) were observed and possibly could be attributed to the characteristics of each vector and their typical biological cycle (hosts and environment). Copyright © 2012 Elsevier GmbH. All rights reserved.

Application of three controls optimally in a vector-borne disease - a mathematical study

NASA Astrophysics Data System (ADS)

Kar, T. K.; Jana, Soovoojeet

2013-10-01

We have proposed and analyzed a vector-borne disease model with three types of controls for the eradication of the disease. Four different classes for the human population namely susceptible, infected, recovered and vaccinated and two different classes for the vector populations namely susceptible and infected are considered. In the first part of our analysis the disease dynamics are described for fixed controls and some inferences have been drawn regarding the spread of the disease. Next the optimal control problem is formulated and solved considering control parameters as time dependent. Different possible combination of controls are used and their effectiveness are compared by numerical simulation.

Problem of ticks and tick-borne diseases in India with special emphasis on progress in tick control research: a review.

PubMed

Ghosh, Srikant; Nagar, Gaurav

2014-12-01

Ticks, as vectors of several zoonotic diseases, are ranked second only to mosquitoes as vectors. The diseases spread by ticks are a major constraint to animal productivity while causing morbidity and mortality in both animals and humans. A number of tick species have been recognised since long as vectors of lethal pathogens, viz. Crimean-Congo haemorrhagic fever virus (CCHFV), Kyasanur forest disease virus (KFDV), Babesia spp, Theileria, Rickettsia conorii, Anaplasma marginale, etc. and the damages caused by them are well-recognised. There is a need to reassess the renewed threat posed by the tick vectors and to prioritize the tick control research programme. This review is focused on the major tick-borne human and animal diseases in India and the progress in vector control research with emphasis on acaricide resistance, tick vaccine and the development of potential phytoacaricides as an integral part of integrated tick control programme.

Towards an integrated approach in surveillance of vector-borne diseases in Europe

PubMed Central

2011-01-01

Vector borne disease (VBD) emergence is a complex and dynamic process. Interactions between multiple disciplines and responsible health and environmental authorities are often needed for an effective early warning, surveillance and control of vectors and the diseases they transmit. To fully appreciate this complexity, integrated knowledge about the human and the vector population is desirable. In the current paper, important parameters and terms of both public health and medical entomology are defined in order to establish a common language that facilitates collaboration between the two disciplines. Special focus is put on the different VBD contexts with respect to the current presence or absence of the disease, the pathogen and the vector in a given location. Depending on the context, whether a VBD is endemic or not, surveillance activities are required to assess disease burden or threat, respectively. Following a decision for action, surveillance activities continue to assess trends. PMID:21967706

Emerging Vector-Borne Diseases.

PubMed

Huntington, Mark K; Allison, Jay; Nair, Dilip

2016-10-01

Several mosquito-borne viral infections have recently emerged in North America; West Nile virus is the most common in the United States. Although West Nile virus generally causes a self-limited, flulike febrile illness, a serious neuroinvasive form may occur. Dengue is the most common vector-borne viral disease worldwide, and it has been a significant public health threat in the United States since 2009. Known as breakbone fever for its severe myalgias and arthralgias, dengue may cause a hemorrhagic syndrome. Chikungunya also causes flulike febrile illness and disabling arthralgias. Although meningoencephalitis may occur with chikungunya, bleeding is uncommon. Symptoms of Zika virus infection are similar to those of dengue, but milder. Zika virus increases the risk of fetal brain abnormalities, including microcephaly, if a pregnant woman is infected. Zika virus is spread through Aedes albopictus mosquito bites, is transmitted sexually, and may rarely spread nonsexually from person to person. Diagnosis of these vectorborne infections is clinical and serologic, and treatment is supportive. Other, well-established vector-borne diseases are also important. Ehrlichiosis is a tick-borne bacterial disease that presents as a nonspecific syndrome of fever, headache, malaise, and myalgias. It is diagnosed via blood smear testing, with confirmatory serology. Ehrlichiosis is treated with doxycycline. Rickettsial infections are transmitted by fleas, mites, and ticks, and severity ranges from mild to life threatening. Rocky Mountain spotted fever, the most significant rickettsial infection, is primarily a clinical diagnosis that presents as fever, headache, myalgias, petechial rash, and tick exposure. Doxycycline is effective for rickettsial infections if administered promptly. Vector avoidance strategies are critical to the prevention of all of these infections.

ZIKA VIRUS INFECTION; VERTICAL TRANSMISSION AND FOETAL CONGENITAL ANOMALIES.

PubMed

Abbasi, Aziz-un-Nisa

2016-01-01

Zika virus (ZIKV) is an arbovirus belonging to flaviviridae family that includes Dengue, West Nile, and Yellow Fever among others. Zika virus was first discovered in 1947 in Zika forest of Uganda. It is a vector borne disease, which has been sporadically reported mostly from Africa, Pacific islands and Southeast Asia since its discovery. ZIKV infection presents as a mild illness with symptoms lasting for several days to a week after the bite of an infected mosquito. Majority of the patients have low grade fever, rash, headaches, joints pain, myalgia, and flu like symptoms. Pregnant women are more vulnerable to ZIKV infection and serious congenital anomalies can occur in foetus through trans-placental transmission. The gestation at which infection is acquired is important. Zika virus infection acquired in early pregnancy poses greater risk. There is no evidence so far about transmission through breast milk. Foetal microcephaly, Gillian Barre syndrome and other neurological and autoimmune syndromes have been reported in areas where Zika outbreaks have occurred. As infection is usually very mild no specific treatment is required. Pregnant women may be advised to take rest, get plenty of fluids. For fever and pain they can take antipyretics like paracetamol. So far no specific drugs or vaccines are available against Zika Virus Infection so prevention is the mainstay against this diseases. As ZIKV infection is a vector borne disease, prevention can be a multi-pronged strategy. These entail vector control interventions, personal protection, environmental sanitation and health education among others.

Newer insecticides for plant virus disease management

USDA-ARS?s Scientific Manuscript database

Effective management of insect and mite vectors of plant pathogens is of crucial importance to minimizing vector-borne diseases in crops. Insecticides play an important role in managing vector populations by reducing the number of individuals that can acquire and transmit a virus, thereby potentiall...

Peculiar liquid-feeding and pathogen transmission behavior of Aedes togoi and comparison with Anopheles sinensis.

PubMed

Lee, Sang Joon; Kang, Dooho; Lee, Seung Chul; Ha, Young-Ran

2016-02-03

Female mosquitoes transmit various diseases as vectors during liquid-feeding. Identifying the determinants of vector efficiency is a major scientific challenge in establishing strategies against these diseases. Infection rate and transmission efficiency are interconnected with the mosquito-induced liquid-feeding flow as main indexes of vector efficiency. However, the relationship between liquid-feeding characteristics and pathogen remains poorly understood. The liquid-feeding behavior of Aedes togoi and Anopheles sinensis was comparatively investigated in conjunction with vector efficiency via micro-particle image velocimetry. The flow rates and ratio of the ejection volume of Aedes togoi were markedly higher than those of Anophels sinensis. These differences would influence pathogen re-ingestion. Wall shear stresses of these mosquito species were also clearly discriminatory affecting the infective rates of vector-borne diseases. The variations in volume of two pump chambers and diameter of proboscis of these mosquito species were compared to determine the differences in the liquid-feeding process. Liquid-feeding characteristics influence vector efficiency; hence, this study can elucidate the vector efficiency of mosquitoes and the vector-pathogen interactions and contribute to the development of strategies against vector-borne diseases.

Peculiar liquid-feeding and pathogen transmission behavior of Aedes togoi and comparison with Anopheles sinensis

NASA Astrophysics Data System (ADS)

Lee, Sang Joon; Kang, Dooho; Lee, Seung Chul; Ha, Young-Ran

2016-02-01

Female mosquitoes transmit various diseases as vectors during liquid-feeding. Identifying the determinants of vector efficiency is a major scientific challenge in establishing strategies against these diseases. Infection rate and transmission efficiency are interconnected with the mosquito-induced liquid-feeding flow as main indexes of vector efficiency. However, the relationship between liquid-feeding characteristics and pathogen remains poorly understood. The liquid-feeding behavior of Aedes togoi and Anopheles sinensis was comparatively investigated in conjunction with vector efficiency via micro-particle image velocimetry. The flow rates and ratio of the ejection volume of Aedes togoi were markedly higher than those of Anophels sinensis. These differences would influence pathogen re-ingestion. Wall shear stresses of these mosquito species were also clearly discriminatory affecting the infective rates of vector-borne diseases. The variations in volume of two pump chambers and diameter of proboscis of these mosquito species were compared to determine the differences in the liquid-feeding process. Liquid-feeding characteristics influence vector efficiency; hence, this study can elucidate the vector efficiency of mosquitoes and the vector-pathogen interactions and contribute to the development of strategies against vector-borne diseases.

Age- and bite-structured models for vector-borne diseases.

PubMed

Rock, K S; Wood, D A; Keeling, M J

2015-09-01

The biology and behaviour of biting insects is a vitally important aspect in the spread of vector-borne diseases. This paper aims to determine, through the use of mathematical models, what effect incorporating vector senescence and realistic feeding patterns has on disease. A novel model is developed to enable the effects of age- and bite-structure to be examined in detail. This original PDE framework extends previous age-structured models into a further dimension to give a new insight into the role of vector biting and its interaction with vector mortality and spread of disease. Through the PDE model, the roles of the vector death and bite rates are examined in a way which is impossible under the traditional ODE formulation. It is demonstrated that incorporating more realistic functions for vector biting and mortality in a model may give rise to different dynamics than those seen under a more simple ODE formulation. The numerical results indicate that the efficacy of control methods that increase vector mortality may not be as great as predicted under a standard host-vector model, whereas other controls including treatment of humans may be more effective than previously thought. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Lyme disease bacterium does not affect attraction to rodent odour in the tick vector.

PubMed

Berret, Jérémy; Voordouw, Maarten Jeroen

2015-04-28

Vector-borne pathogens experience a conflict of interest when the arthropod vector chooses a vertebrate host that is incompetent for pathogen transmission. The qualitative manipulation hypothesis suggests that vector-borne pathogens can resolve this conflict in their favour by manipulating the host choice behaviour of the arthropod vector. European Lyme disease is a model system for studying this conflict because Ixodes ricinus is a generalist tick species that vectors Borrelia pathogens that are specialized on different classes of vertebrate hosts. Avian specialists like B. garinii cannot survive in rodent reservoir hosts and vice versa for rodent specialists like B. afzelii. The present study tested whether Borrelia genospecies influenced the attraction of field-collected I. ricinus nymphs to rodent odours. Nymphs were significantly attracted to questing perches that had been scented with mouse odours. However, there was no difference in questing behaviour between nymphs infected with rodent- versus bird-specialized Borrelia genospecies. Our study suggests that the tick, and not the pathogen, controls the early stages of host choice behaviour.

Improvement of Disease Prediction and Modeling through the Use of Meteorological Ensembles: Human Plague in Uganda

PubMed Central

Moore, Sean M.; Monaghan, Andrew; Griffith, Kevin S.; Apangu, Titus; Mead, Paul S.; Eisen, Rebecca J.

2012-01-01

Climate and weather influence the occurrence, distribution, and incidence of infectious diseases, particularly those caused by vector-borne or zoonotic pathogens. Thus, models based on meteorological data have helped predict when and where human cases are most likely to occur. Such knowledge aids in targeting limited prevention and control resources and may ultimately reduce the burden of diseases. Paradoxically, localities where such models could yield the greatest benefits, such as tropical regions where morbidity and mortality caused by vector-borne diseases is greatest, often lack high-quality in situ local meteorological data. Satellite- and model-based gridded climate datasets can be used to approximate local meteorological conditions in data-sparse regions, however their accuracy varies. Here we investigate how the selection of a particular dataset can influence the outcomes of disease forecasting models. Our model system focuses on plague (Yersinia pestis infection) in the West Nile region of Uganda. The majority of recent human cases have been reported from East Africa and Madagascar, where meteorological observations are sparse and topography yields complex weather patterns. Using an ensemble of meteorological datasets and model-averaging techniques we find that the number of suspected cases in the West Nile region was negatively associated with dry season rainfall (December-February) and positively with rainfall prior to the plague season. We demonstrate that ensembles of available meteorological datasets can be used to quantify climatic uncertainty and minimize its impacts on infectious disease models. These methods are particularly valuable in regions with sparse observational networks and high morbidity and mortality from vector-borne diseases. PMID:23024750

Evidence that implicit assumptions of ‘no evolution’ of disease vectors in changing environments can be violated on a rapid timescale

PubMed Central

Egizi, Andrea; Fefferman, Nina H.; Fonseca, Dina M.

2015-01-01

Projected impacts of climate change on vector-borne disease dynamics must consider many variables relevant to hosts, vectors and pathogens, including how altered environmental characteristics might affect the spatial distributions of vector species. However, many predictive models for vector distributions consider their habitat requirements to be fixed over relevant time-scales, when they may actually be capable of rapid evolutionary change and even adaptation. We examine the genetic signature of a spatial expansion by an invasive vector into locations with novel temperature conditions compared to its native range as a proxy for how existing vector populations may respond to temporally changing habitat. Specifically, we compare invasions into different climate ranges and characterize the importance of selection from the invaded habitat. We demonstrate that vector species can exhibit evolutionary responses (altered allelic frequencies) to a temperature gradient in as little as 7–10 years even in the presence of high gene flow, and further, that this response varies depending on the strength of selection. We interpret these findings in the context of climate change predictions for vector populations and emphasize the importance of incorporating vector evolution into models of future vector-borne disease dynamics. PMID:25688024

Genetic shifting: a novel approach for controlling vector-borne diseases.

PubMed

Powell, Jeffrey R; Tabachnick, Walter J

2014-06-01

Rendering populations of vectors of diseases incapable of transmitting pathogens through genetic methods has long been a goal of vector geneticists. We outline a method to achieve this goal that does not involve the introduction of any new genetic variants to the target population. Rather we propose that shifting the frequencies of naturally occurring alleles that confer refractoriness to transmission can reduce transmission below a sustainable level. The program employs methods successfully used in plant and animal breeding. Because no artificially constructed genetically modified organisms (GMOs) are introduced into the environment, the method is minimally controversial. We use Aedes aegypti and dengue virus (DENV) for illustrative purposes but point out that the proposed program is generally applicable to vector-borne disease control. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mosquitoes on a plane: Disinsection will not stop the spread of vector-borne pathogens, a simulation study

PubMed Central

Mier-y-Teran-Romero, Luis; Tatem, Andrew J.

2017-01-01

Mosquito-borne diseases are increasingly being recognized as global threats, with increased air travel accelerating their occurrence in travelers and their spread to new locations. Since the early days of aviation, concern over the possible transportation of infected mosquitoes has led to recommendations to disinsect aircraft. Despite rare reports of mosquitoes, most likely transported on aircraft, infecting people far from endemics areas, it is unclear how important the role of incidentally transported mosquitoes is compared to the role of traveling humans. We used data for Plasmodium falciparum and dengue viruses to estimate the probability of introduction of these pathogens by mosquitoes and by humans via aircraft under ideal conditions. The probability of introduction of either pathogen by mosquitoes is low due to few mosquitoes being found on aircraft, low infection prevalence among mosquitoes, and high mortality. Even without disinsection, introduction via infected human travelers was far more likely than introduction by infected mosquitoes; more than 1000 times more likely for P. falciparum and more than 200 times more likely for dengue viruses. Even in the absence of disinsection and under the most favorable conditions, introduction of mosquito-borne pathogens via air travel is far more likely to occur as a result of an infected human travelling rather than the incidental transportation of infected mosquitoes. Thus, while disinsection may serve a role in preventing the spread of vector species and other invasive insects, it is unlikely to impact the spread of mosquito-borne pathogens. PMID:28672006

Public health and vector-borne diseases - a new concept for risk governance.

PubMed

Schmidt, K; Dressel, K M; Niedrig, M; Mertens, M; Schüle, S A; Groschup, M H

2013-12-01

Public Health is defined as an interdisciplinary multilevel approach that deals with questions of preventing diseases at the population level. In this context, this paper focuses on vector-borne diseases as an important threat with an increasing impact on human and animal health. Emphasis is laid on an integrated health approach ('One-Health' initiative) as it recognizes the interrelated nature of both human and animal health. The importance of vector-borne diseases to new and emerging diseases in Europe was demonstrated, for example, by the recent outbreak of West Nile virus infections in Greece, Northern Italy and Hungary; the spread of Crimean-Congo haemorrhagic fever virus across Turkey, south-western countries of the former USSR and the Balkans; the dramatic increase in hantavirus infections in Germany in 2012; and the dengue virus outbreak in Portugal in the same year. This paper provides a systematic approach for the analysis, assessment and governance of emerging health risks attributed to vector-borne diseases by using a holistic approach developed by the International Risk Governance Council (IRGC), called the 'IRGC Risk Governance Framework'. It can be used by decision-makers and general Public Health authorities in order to evaluate the situation regarding any specific pathogen or Public Health risk and to decide if additional measures should be implemented. © 2013 Blackwell Verlag GmbH.

Visualization of Microbiota in Tick Guts by Whole-mount In Situ Hybridization.

PubMed

Moss, Caitlin E; Robson, Andrew; Fikrig, Erol; Narasimhan, Sukanya

2018-06-01

Infectious diseases transmitted by arthropod vectors continue to pose a significant threat to human health worldwide. The pathogens causing these diseases, do not exist in isolation when they colonize the vector; rather, they likely engage in interactions with resident microorganisms in the gut lumen. The vector microbiota has been demonstrated to play an important role in pathogen transmission for several vector-borne diseases. Whether resident bacteria in the gut of the Ixodes scapularis tick, the vector of several human pathogens including Borrelia burgdorferi, influence tick transmission of pathogens is not determined. We require methods for characterizing the composition of the bacteria associated with the tick gut to facilitate a better understanding of potential interspecies interactions in the tick gut. Using whole-mount in situ hybridization to visualize RNA transcripts associated with particular bacterial species allows for the collection of qualitative data regarding the abundance and distribution of the microbiota in intact tissue. This technique can be used to examine changes in the gut microbiota milieu over the course of tick feeding and can also be applied to analyze expression of tick genes. Staining of whole tick guts yield information about the gross spatial distribution of target RNA in the tissue without the need for three-dimensional reconstruction and is less affected by environmental contamination, which often confounds the sequencing-based methods frequently used to study complex microbial communities. Overall, this technique is a valuable tool that can be used to better understand vector-pathogen-microbiota interactions and their role in disease transmission.

A survey of basic reproductive ratios in vector-borne disease transmission modeling

NASA Astrophysics Data System (ADS)

Soewono, E.; Aldila, D.

2015-03-01

Vector-borne diseases are commonly known in tropical and subtropical countries. These diseases have contributed to more than 10% of world infectious disease cases. Among the vectors responsible for transmitting the diseases are mosquitoes, ticks, fleas, flies, bugs and worms. Several of the diseases are known to contribute to the increasing threat to human health such as malaria, dengue, filariasis, chikungunya, west nile fever, yellow fever, encephalistis, and anthrax. It is necessary to understand the real process of infection, factors which contribute to the complication of the transmission in order to come up with a good and sound mathematical model. Although it is not easy to simulate the real transmission process of the infection, we could say that almost all models have been developed from the already long known Host-Vector model. It constitutes the main transmission processes i.e. birth, death, infection and recovery. From this simple model, the basic concepts of Disease Free and Endemic Equilibria and Basic Reproductive Ratio can be well explained and understood. Theoretical, modeling, control and treatment aspects of disease transmission problems have then been developed for various related diseases. General construction as well as specific forms of basic reproductive ratios for vector-borne diseases are discusses here.

The risk of incomplete personal protection coverage in vector-borne disease.

PubMed

Miller, Ezer; Dushoff, Jonathan; Huppert, Amit

2016-02-01

Personal protection (PP) techniques, such as insecticide-treated nets, repellents and medications, include some of the most important and commonest ways used today to protect individuals from vector-borne infectious diseases. In this study, we explore the possibility that a PP intervention with partial coverage may have the counterintuitive effect of increasing disease burden at the population level, by increasing the biting intensity on the unprotected portion of the population. To this end, we have developed a dynamic model which incorporates parameters that describe the potential effects of PP on vector searching and biting behaviour and calculated its basic reproductive rate, R0. R0 is a well-established threshold of disease risk; the higher R0 is above unity, the stronger the disease onset intensity. When R0 is below unity, the disease is typically unable to persist. The model analysis revealed that partial coverage with popular PP techniques can realistically lead to a substantial increase in the reproductive number. An increase in R0 implies an increase in disease burden and difficulties in eradication efforts within certain parameter regimes. Our findings therefore stress the importance of studying vector behavioural patterns in response to PP interventions for future mitigation of vector-borne diseases. © 2016 The Author(s).

Reservoir host competence and the role of domestic and commensal hosts in the transmission of Trypanosoma cruzi.

PubMed

Gürtler, Ricardo E; Cardinal, M V

2015-11-01

We review the epidemiological role of domestic and commensal hosts of Trypanosoma cruzi using a quantitative approach, and compiled >400 reports on their natural infection. We link the theory underlying simple mathematical models of vector-borne parasite transmission to the types of evidence used for reservoir host identification: mean duration of infectious life; host infection and infectiousness; and host-vector contact. The infectiousness of dogs or cats most frequently exceeded that of humans. The host-feeding patterns of major vectors showed wide variability among and within triatomine species related to their opportunistic behavior and variable ecological, biological and social contexts. The evidence shows that dogs, cats, commensal rodents and domesticated guinea pigs are able to maintain T. cruzi in the absence of any other host species. They play key roles as amplifying hosts and sources of T. cruzi in many (peri)domestic transmission cycles covering a broad diversity of ecoregions, ecotopes and triatomine species: no other domestic animal plays that role. Dogs comply with the desirable attributes of natural sentinels and sometimes were a point of entry of sylvatic parasite strains. The controversies on the role of cats and other hosts illustrate the issues that hamper assessing the relative importance of reservoir hosts on the basis of fragmentary evidence. We provide various study cases of how eco-epidemiological and genetic-marker evidence helped to unravel transmission cycles and identify the implicated hosts. Keeping dogs, cats and rodents out of human sleeping quarters and reducing their exposure to triatomine bugs are predicted to strongly reduce transmission risks. Copyright © 2015. Published by Elsevier B.V.

Broad patterns in domestic vector-borne Trypanosoma cruzi transmission dynamics: synanthropic animals and vector control.

PubMed

Peterson, Jennifer K; Bartsch, Sarah M; Lee, Bruce Y; Dobson, Andrew P

2015-10-22

Chagas disease (caused by Trypanosoma cruzi) is the most important neglected tropical disease (NTD) in Latin America, infecting an estimated 5.7 million people in the 21 countries where it is endemic. It is one of the NTDs targeted for control and elimination by the 2020 London Declaration goals, with the first goal being to interrupt intra-domiciliary vector-borne T. cruzi transmission. A key question in domestic T. cruzi transmission is the role that synanthropic animals play in T. cruzi transmission to humans. Here, we ask, (1) do synanthropic animals need to be targeted in Chagas disease prevention policies?, and (2) how does the presence of animals affect the efficacy of vector control? We developed a simple mathematical model to simulate domestic vector-borne T. cruzi transmission and to specifically examine the interaction between the presence of synanthropic animals and effects of vector control. We used the model to explore how the interactions between triatomine bugs, humans and animals impact the number and proportion of T. cruzi-infected bugs and humans. We then examined how T. cruzi dynamics change when control measures targeting vector abundance are introduced into the system. We found that the presence of synanthropic animals slows the speed of T. cruzi transmission to humans, and increases the sensitivity of T. cruzi transmission dynamics to vector control measures at comparable triatomine carrying capacities. However, T. cruzi transmission is amplified when triatomine carrying capacity increases with the abundance of syntathoropic hosts. Our results suggest that in domestic T. cruzi transmission scenarios where no vector control measures are in place, a reduction in synanthropic animals may slow T. cruzi transmission to humans, but it would not completely eliminate transmission. To reach the 2020 goal of interrupting intra-domiciliary T. cruzi transmission, it is critical to target vector populations. Additionally, where vector control measures are in place, synanthropic animals may be beneficial.

Integrating Transgenic Vector Manipulation with Clinical Interventions to Manage Vector-Borne Diseases.

PubMed

Okamoto, Kenichi W; Gould, Fred; Lloyd, Alun L

2016-03-01

Many vector-borne diseases lack effective vaccines and medications, and the limitations of traditional vector control have inspired novel approaches based on using genetic engineering to manipulate vector populations and thereby reduce transmission. Yet both the short- and long-term epidemiological effects of these transgenic strategies are highly uncertain. If neither vaccines, medications, nor transgenic strategies can by themselves suffice for managing vector-borne diseases, integrating these approaches becomes key. Here we develop a framework to evaluate how clinical interventions (i.e., vaccination and medication) can be integrated with transgenic vector manipulation strategies to prevent disease invasion and reduce disease incidence. We show that the ability of clinical interventions to accelerate disease suppression can depend on the nature of the transgenic manipulation deployed (e.g., whether vector population reduction or replacement is attempted). We find that making a specific, individual strategy highly effective may not be necessary for attaining public-health objectives, provided suitable combinations can be adopted. However, we show how combining only partially effective antimicrobial drugs or vaccination with transgenic vector manipulations that merely temporarily lower vector competence can amplify disease resurgence following transient suppression. Thus, transgenic vector manipulation that cannot be sustained can have adverse consequences-consequences which ineffective clinical interventions can at best only mitigate, and at worst temporarily exacerbate. This result, which arises from differences between the time scale on which the interventions affect disease dynamics and the time scale of host population dynamics, highlights the importance of accounting for the potential delay in the effects of deploying public health strategies on long-term disease incidence. We find that for systems at the disease-endemic equilibrium, even modest perturbations induced by weak interventions can exhibit strong, albeit transient, epidemiological effects. This, together with our finding that under some conditions combining strategies could have transient adverse epidemiological effects suggests that a relatively long time horizon may be necessary to discern the efficacy of alternative intervention strategies.

Integrating Transgenic Vector Manipulation with Clinical Interventions to Manage Vector-Borne Diseases

PubMed Central

Okamoto, Kenichi W.; Gould, Fred; Lloyd, Alun L.

2016-01-01

Many vector-borne diseases lack effective vaccines and medications, and the limitations of traditional vector control have inspired novel approaches based on using genetic engineering to manipulate vector populations and thereby reduce transmission. Yet both the short- and long-term epidemiological effects of these transgenic strategies are highly uncertain. If neither vaccines, medications, nor transgenic strategies can by themselves suffice for managing vector-borne diseases, integrating these approaches becomes key. Here we develop a framework to evaluate how clinical interventions (i.e., vaccination and medication) can be integrated with transgenic vector manipulation strategies to prevent disease invasion and reduce disease incidence. We show that the ability of clinical interventions to accelerate disease suppression can depend on the nature of the transgenic manipulation deployed (e.g., whether vector population reduction or replacement is attempted). We find that making a specific, individual strategy highly effective may not be necessary for attaining public-health objectives, provided suitable combinations can be adopted. However, we show how combining only partially effective antimicrobial drugs or vaccination with transgenic vector manipulations that merely temporarily lower vector competence can amplify disease resurgence following transient suppression. Thus, transgenic vector manipulation that cannot be sustained can have adverse consequences—consequences which ineffective clinical interventions can at best only mitigate, and at worst temporarily exacerbate. This result, which arises from differences between the time scale on which the interventions affect disease dynamics and the time scale of host population dynamics, highlights the importance of accounting for the potential delay in the effects of deploying public health strategies on long-term disease incidence. We find that for systems at the disease-endemic equilibrium, even modest perturbations induced by weak interventions can exhibit strong, albeit transient, epidemiological effects. This, together with our finding that under some conditions combining strategies could have transient adverse epidemiological effects suggests that a relatively long time horizon may be necessary to discern the efficacy of alternative intervention strategies. PMID:26962871

[Climate change - a pioneer for the expansion of canine vector-borne diseases?].

PubMed

Krämer, F; Mencke, N

2011-01-01

Vector-transmitted diseases are one of the major contributors to the global burden of disease in humans and animals. Climate change is consistently held responsible for the spread of parasitic acarid and insect vectors such as ticks, fleas, sand flies and mosquitoes, and their transmitted pathogens (in the case of the dog the so-called canine vector-borne diseases [CVBD]). Currently, there is only insufficient data available to prove whether climate change is a major driving force for vector and disease expansion, but the evidence is growing. Other reasons, such as ecological, demographic and socio-economic factors, e.g. pet travel into and pet import from endemic areas, also play a role in this development. Apart from all the controversial discussion of the factors leading to vector and disease expansion, preventative measures should include dog owners' education as they are responsible for individual parasite protection as well as for the minimisation of adverse risk behaviour, e.g. regarding pet travel. Broad-spectrum vector control should be practised by using parasiticides that repel and kill blood feeders in order to minimize the risk of CVBD-pathogen transmission.

Research on the ecology of ticks and tick-borne pathogens—methodological principles and caveats

PubMed Central

Estrada-Peña, Agustín; Gray, Jeremy S.; Kahl, Olaf; Lane, Robert S.; Nijhof, Ard M.

2013-01-01

Interest in tick-transmitted pathogens has experienced an upsurge in the past few decades. Routine application of tools for the detection of fragments of foreign DNA in ticks, together with a high degree of interest in the quantification of disease risk for humans, has led to a marked increase in the number of reports on the eco-epidemiology of tick-borne diseases. However, procedural errors continue to accumulate in the scientific literature, resulting in misleading information. For example, unreliable identification of ticks and pathogens, erroneous interpretations of short-term field studies, and the hasty acceptance of some tick species as vectors have led to ambiguities regarding the vector role of these arthropods. In this review, we focus on the ecological features driving the life cycle of ticks and the resulting effects on the eco-epidemiology of tick-transmitted pathogens. We review the factors affecting field collections of ticks, and we describe the biologically and ecologically appropriate procedures for describing tick host-seeking activity and its correlation with environmental traits. We detail the climatic variables that have biological importance on ticks and explain how they should be properly measured and analyzed. We also provide evidence to critically reject the use of some environmental traits that are being increasingly reported as the drivers of the behavior of ticks. With the aim of standardization, we propose unambiguous definitions of the status of hosts and ticks regarding their ability to maintain and spread a given pathogen. We also describe laboratory procedures and standards for evaluating the vectorial capacity of a tick or the reservoir role of a host. This approach should provide a coherent framework for the reporting of research findings concerning ticks and tick-borne diseases. PMID:23964348

Research on the ecology of ticks and tick-borne pathogens--methodological principles and caveats.

PubMed

Estrada-Peña, Agustín; Gray, Jeremy S; Kahl, Olaf; Lane, Robert S; Nijhof, Ard M

2013-01-01

Interest in tick-transmitted pathogens has experienced an upsurge in the past few decades. Routine application of tools for the detection of fragments of foreign DNA in ticks, together with a high degree of interest in the quantification of disease risk for humans, has led to a marked increase in the number of reports on the eco-epidemiology of tick-borne diseases. However, procedural errors continue to accumulate in the scientific literature, resulting in misleading information. For example, unreliable identification of ticks and pathogens, erroneous interpretations of short-term field studies, and the hasty acceptance of some tick species as vectors have led to ambiguities regarding the vector role of these arthropods. In this review, we focus on the ecological features driving the life cycle of ticks and the resulting effects on the eco-epidemiology of tick-transmitted pathogens. We review the factors affecting field collections of ticks, and we describe the biologically and ecologically appropriate procedures for describing tick host-seeking activity and its correlation with environmental traits. We detail the climatic variables that have biological importance on ticks and explain how they should be properly measured and analyzed. We also provide evidence to critically reject the use of some environmental traits that are being increasingly reported as the drivers of the behavior of ticks. With the aim of standardization, we propose unambiguous definitions of the status of hosts and ticks regarding their ability to maintain and spread a given pathogen. We also describe laboratory procedures and standards for evaluating the vectorial capacity of a tick or the reservoir role of a host. This approach should provide a coherent framework for the reporting of research findings concerning ticks and tick-borne diseases.

Multiple Insecticide Resistances in the Disease Vector Culex p. Quinquefasciatus from Western Indian Ocean

PubMed Central

Pocquet, Nicolas; Milesi, Pascal; Makoundou, Patrick; Unal, Sandra; Zumbo, Betty; Atyame, Célestine; Darriet, Frédéric; Dehecq, Jean-Sébastien; Thiria, Julien; Bheecarry, Ambicadutt; Iyaloo, Diana P.; Weill, Mylène; Chandre, Fabrice; Labbé, Pierrick

2013-01-01

Several mosquito-borne diseases affect the Western Indian Ocean islands. Culex pipiens quinquefasciatus is one of these vectors and transmits filariasis, Rift Valley and West Nile viruses and the Japanese encephalitis. To limit the impact of these diseases on public health, considerable vector control efforts have been implemented since the 50s, mainly through the use of neurotoxic insecticides belonging to Organochlorines (OC), Organophosphates (OP) and pyrethroids (PYR) families. However, mosquito control failures have been reported on site, and they were probably due to the selection of resistant individuals in response to insecticide exposure. In this study, we used different approaches to establish a first regional assessment of the levels and mechanisms of resistance to various insecticides. Bioassays were used to evaluate resistance to various insecticides, enzyme activity was measured to assess the presence of metabolic resistances through elevated detoxification, and molecular identification of known resistance alleles was investigated to determine the frequency of target-site mutations. These complementary approaches showed that resistance to the most used insecticides families (OC, OP and PYR) is widespread at a regional scale. However, the distribution of the different resistance genes is quite heterogeneous among the islands, some being found at high frequencies everywhere, others being frequent in some islands and absent in others. Moreover, two resistance alleles displayed clinal distributions in Mayotte and La Réunion, probably as a result of a heterogeneous selection due to local treatment practices. These widespread and diverse resistance mechanisms reduce the capacity of resistance management through classical strategies (e.g. insecticide rotation). In case of a disease outbreak, it could undermine the efforts of the vector control services, as only few compounds could be used. It thus becomes urgent to find alternatives to control populations of Cx. p. quinquefasciatus in the Indian Ocean. PMID:24204997

A Sero-epidemiological Study of Arboviral Fevers in Djibouti, Horn of Africa

PubMed Central

Andayi, Fred; Charrel, Remi N.; Kieffer, Alexia; Richet, Herve; Pastorino, Boris; Leparc-Goffart, Isabelle; Ahmed, Ammar Abdo; Carrat, Fabrice; Flahault, Antoine; de Lamballerie, Xavier

2014-01-01

Arboviral infections have repeatedly been reported in the republic of Djibouti, consistent with the fact that essential vectors for arboviral diseases are endemic in the region. However, there is a limited recent information regarding arbovirus circulation, and the associated risk predictors to human exposure are largely unknown. We performed, from November 2010 to February 2011 in the Djibouti city general population, a cross-sectional ELISA and sero-neutralisation-based sero-epidemiological analysis nested in a household cohort, which investigated the arboviral infection prevalence and risk factors, stratified by their vectors of transmission. Antibodies to dengue virus (21.8%) were the most frequent. Determinants of infection identified by multivariate analysis pointed to sociological and environmental exposure to the bite of Aedes mosquitoes. The population was broadly naïve against Chikungunya (2.6%) with risk factors mostly shared with dengue. The detection of limited virus circulation was followed by a significant Chikungunya outbreak a few months after our study. Antibodies to West Nile virus were infrequent (0.6%), but the distribution of cases faithfully followed previous mapping of infected Culex mosquitoes. The seroprevalence of Rift valley fever virus was 2.2%, and non-arboviral transmission was suggested. Finally, the study indicated the circulation of Toscana-related viruses (3.7%), and a limited number of cases suggested infection by tick-borne encephalitis or Alkhumra related viruses, which deserve further investigations to identify the viruses and vectors implicated. Overall, most of the arboviral cases' predictors were statistically best described by the individuals' housing space and neighborhood environmental characteristics, which correlated with the ecological actors of their respective transmission vectors' survival in the local niche. This study has demonstrated autochthonous arboviral circulations in the republic of Djibouti, and provides an epidemiological inventory, with useful findings for risk mapping and future prevention and control programs. PMID:25502692

A sero-epidemiological study of arboviral fevers in Djibouti, Horn of Africa.

PubMed

Andayi, Fred; Charrel, Remi N; Kieffer, Alexia; Richet, Herve; Pastorino, Boris; Leparc-Goffart, Isabelle; Ahmed, Ammar Abdo; Carrat, Fabrice; Flahault, Antoine; de Lamballerie, Xavier

2014-12-01

Arboviral infections have repeatedly been reported in the republic of Djibouti, consistent with the fact that essential vectors for arboviral diseases are endemic in the region. However, there is a limited recent information regarding arbovirus circulation, and the associated risk predictors to human exposure are largely unknown. We performed, from November 2010 to February 2011 in the Djibouti city general population, a cross-sectional ELISA and sero-neutralisation-based sero-epidemiological analysis nested in a household cohort, which investigated the arboviral infection prevalence and risk factors, stratified by their vectors of transmission. Antibodies to dengue virus (21.8%) were the most frequent. Determinants of infection identified by multivariate analysis pointed to sociological and environmental exposure to the bite of Aedes mosquitoes. The population was broadly naïve against Chikungunya (2.6%) with risk factors mostly shared with dengue. The detection of limited virus circulation was followed by a significant Chikungunya outbreak a few months after our study. Antibodies to West Nile virus were infrequent (0.6%), but the distribution of cases faithfully followed previous mapping of infected Culex mosquitoes. The seroprevalence of Rift valley fever virus was 2.2%, and non-arboviral transmission was suggested. Finally, the study indicated the circulation of Toscana-related viruses (3.7%), and a limited number of cases suggested infection by tick-borne encephalitis or Alkhumra related viruses, which deserve further investigations to identify the viruses and vectors implicated. Overall, most of the arboviral cases' predictors were statistically best described by the individuals' housing space and neighborhood environmental characteristics, which correlated with the ecological actors of their respective transmission vectors' survival in the local niche. This study has demonstrated autochthonous arboviral circulations in the republic of Djibouti, and provides an epidemiological inventory, with useful findings for risk mapping and future prevention and control programs.

Climate change and threat of vector-borne diseases in India: are we prepared?

PubMed

Dhiman, Ramesh C; Pahwa, Sharmila; Dhillon, G P S; Dash, Aditya P

2010-03-01

It is unequivocal that climate change is happening and is likely to expand the geographical distribution of several vector-borne diseases, including malaria and dengue etc. to higher altitudes and latitudes. India is endemic for six major vector-borne diseases (VBD) namely malaria, dengue, chikungunya, filariasis, Japanese encephalitis and visceral leishmaniasis. Over the years, there has been reduction in the incidence of almost all the diseases except chikungunya which has re-emerged since 2005. The upcoming issue of climate change has surfaced as a new threat and challenge for ongoing efforts to contain vector-borne diseases. There is greater awareness about the potential impacts of climate change on VBDs in India and research institutions and national authorities have initiated actions to assess the impacts. Studies undertaken in India on malaria in the context of climate change impact reveal that transmission windows in Punjab, Haryana, Jammu and Kashmir and north-eastern states are likely to extend temporally by 2-3 months and in Orissa, Andhra Pradesh and Tamil Nadu there may be reduction in transmission windows. Using PRECIS model (driven by HadRM2) at the resolution of 50 x 50 Km for daily temperature and relative humidity for year 2050, it was found that Orissa, West Bengal and southern parts of Assam will still remain malarious and transmission windows will open up in Himachal Pradesh and north-eastern states etc. Impact of climate change on dengue also reveals increase in transmission with 2 C rise in temperature in northern India. Re-emergence of kala-azar in northern parts of India and reappearance of chikungunya mainly in southern states of India has also been discussed. The possible need to address the threat and efforts made in India have also been highlighted. The paper concludes with a positive lead that with better preparedness threat of climate change on vector-borne diseases may be negated.

Mobilizing community-based health insurance to enhance awareness & prevention of airborne, vector-borne & waterborne diseases in rural India

PubMed Central

Panda, Pradeep; Chakraborty, Arpita; Dror, David M.

2015-01-01

Background & objectives: Despite remarkable progress in airborne, vector-borne and waterborne diseases in India, the morbidity associated with these diseases is still high. Many of these diseases are controllable through awareness and preventive practice. This study was an attempt to evaluate the effectiveness of a preventive care awareness campaign in enhancing knowledge related with airborne, vector-borne and waterborne diseases, carried out in 2011 in three rural communities in India (Pratapgarh and Kanpur-Dehat in Uttar Pradesh and Vaishali in Bihar). Methods: Data for this analysis were collected from two surveys, one done before the campaign and the other after it, each of 300 randomly selected households drawn from a larger sample of Self-Help Groups (SHGs) members invited to join community-based health insurance (CBHI) schemes. Results: The results showed a significant increase both in awareness (34%, p<0.001) and in preventive practices (48%, P=0.001), suggesting that the awareness campaign was effective. However, average practice scores (0.31) were substantially lower than average awareness scores (0.47), even in post-campaign. Awareness and preventive practices were less prevalent in vector-borne diseases than in airborne and waterborne diseases. Education was positively associated with both awareness and practice scores. The awareness scores were positive and significant determinants of the practice scores, both in the pre- and in the post-campaign results. Affiliation to CBHI had significant positive influence on awareness and on practice scores in the post-campaign period. Interpretation & conclusions: The results suggest that well-crafted health educational campaigns can be effective in raising awareness and promoting health-enhancing practices in resource-poor settings. It also confirms that CBHI can serve as a platform to enhance awareness to risks of exposure to airborne, vector-borne and waterborne diseases, and encourage preventive practices. PMID:26354212

Criteria for the prioritization of public health interventions for climate-sensitive vector-borne diseases in Quebec.

PubMed

Hongoh, Valerie; Gosselin, Pierre; Michel, Pascal; Ravel, André; Waaub, Jean-Philippe; Campagna, Céline; Samoura, Karim

2017-01-01

Prioritizing resources for optimal responses to an ever growing list of existing and emerging infectious diseases represents an important challenge to public health. In the context of climate change, there is increasing anticipated variability in the occurrence of infectious diseases, notably climate-sensitive vector-borne diseases. An essential step in prioritizing efforts is to identify what considerations and concerns to take into account to guide decisions and thus set disease priorities. This study was designed to perform a comprehensive review of criteria for vector-borne disease prioritization, assess their applicability in a context of climate change with a diverse cross-section of stakeholders in order to produce a baseline list of considerations to use in this decision-making context. Differences in stakeholder choices were examined with regards to prioritization of these criteria for research, surveillance and disease prevention and control objectives. A preliminary list of criteria was identified following a review of the literature. Discussions with stakeholders were held to consolidate and validate this list of criteria and examine their effects on disease prioritization. After this validation phase, a total of 21 criteria were retained. A pilot vector-borne disease prioritization exercise was conducted using PROMETHEE to examine the effects of the retained criteria on prioritization in different intervention domains. Overall, concerns expressed by stakeholders for prioritization were well aligned with categories of criteria identified in previous prioritization studies. Weighting by category was consistent between stakeholders overall, though some significant differences were found between public health and non-public health stakeholders. From this exercise, a general model for climate-sensitive vector-borne disease prioritization has been developed that can be used as a starting point for further public health prioritization exercises relating to research, surveillance, and prevention and control interventions in a context of climate change. Multi-stakeholder engagement in prioritization can help broaden the range of criteria taken into account, offer opportunities for early identification of potential challenges and may facilitate acceptability of any resulting decisions.

Invasion of two tick-borne diseases across New England: harnessing human surveillance data to capture underlying ecological invasion processes

PubMed Central

Walter, Katharine S.; Pepin, Kim M.; Webb, Colleen T.; Gaff, Holly D.; Krause, Peter J.; Pitzer, Virginia E.; Diuk-Wasser, Maria A.

2016-01-01

Modelling the spatial spread of vector-borne zoonotic pathogens maintained in enzootic transmission cycles remains a major challenge. The best available spatio-temporal data on pathogen spread often take the form of human disease surveillance data. By applying a classic ecological approach—occupancy modelling—to an epidemiological question of disease spread, we used surveillance data to examine the latent ecological invasion of tick-borne pathogens. Over the last half-century, previously undescribed tick-borne pathogens including the agents of Lyme disease and human babesiosis have rapidly spread across the northeast United States. Despite their epidemiological importance, the mechanisms of tick-borne pathogen invasion and drivers underlying the distinct invasion trajectories of the co-vectored pathogens remain unresolved. Our approach allowed us to estimate the unobserved ecological processes underlying pathogen spread while accounting for imperfect detection of human cases. Our model predicts that tick-borne diseases spread in a diffusion-like manner with occasional long-distance dispersal and that babesiosis spread exhibits strong dependence on Lyme disease. PMID:27252022

An economic evaluation of vector control in the age of a dengue vaccine.

PubMed

Fitzpatrick, Christopher; Haines, Alexander; Bangert, Mathieu; Farlow, Andrew; Hemingway, Janet; Velayudhan, Raman

2017-08-01

Dengue is a rapidly emerging vector-borne Neglected Tropical Disease, with a 30-fold increase in the number of cases reported since 1960. The economic cost of the illness is measured in the billions of dollars annually. Environmental change and unplanned urbanization are conspiring to raise the health and economic cost even further beyond the reach of health systems and households. The health-sector response has depended in large part on control of the Aedes aegypti and Ae. albopictus (mosquito) vectors. The cost-effectiveness of the first-ever dengue vaccine remains to be evaluated in the field. In this paper, we examine how it might affect the cost-effectiveness of sustained vector control. We employ a dynamic Markov model of the effects of vector control on dengue in both vectors and humans over a 15-year period, in six countries: Brazil, Columbia, Malaysia, Mexico, the Philippines, and Thailand. We evaluate the cost (direct medical costs and control programme costs) and cost-effectiveness of sustained vector control, outbreak response and/or medical case management, in the presence of a (hypothetical) highly targeted and low cost immunization strategy using a (non-hypothetical) medium-efficacy vaccine. Sustained vector control using existing technologies would cost little more than outbreak response, given the associated costs of medical case management. If sustained use of existing or upcoming technologies (of similar price) reduce vector populations by 70-90%, the cost per disability-adjusted life year averted is 2013 US$ 679-1331 (best estimates) relative to no intervention. Sustained vector control could be highly cost-effective even with less effective technologies (50-70% reduction in vector populations) and in the presence of a highly targeted and low cost immunization strategy using a medium-efficacy vaccine. Economic evaluation of the first-ever dengue vaccine is ongoing. However, even under very optimistic assumptions about a highly targeted and low cost immunization strategy, our results suggest that sustained vector control will continue to play an important role in mitigating the impact of environmental change and urbanization on human health. If additional benefits for the control of other Aedes borne diseases, such as Chikungunya, yellow fever and Zika fever are taken into account, the investment case is even stronger. High-burden endemic countries should proceed to map populations to be covered by sustained vector control.

An economic evaluation of vector control in the age of a dengue vaccine

PubMed Central

Haines, Alexander; Bangert, Mathieu; Farlow, Andrew; Hemingway, Janet; Velayudhan, Raman

2017-01-01

Introduction Dengue is a rapidly emerging vector-borne Neglected Tropical Disease, with a 30-fold increase in the number of cases reported since 1960. The economic cost of the illness is measured in the billions of dollars annually. Environmental change and unplanned urbanization are conspiring to raise the health and economic cost even further beyond the reach of health systems and households. The health-sector response has depended in large part on control of the Aedes aegypti and Ae. albopictus (mosquito) vectors. The cost-effectiveness of the first-ever dengue vaccine remains to be evaluated in the field. In this paper, we examine how it might affect the cost-effectiveness of sustained vector control. Methods We employ a dynamic Markov model of the effects of vector control on dengue in both vectors and humans over a 15-year period, in six countries: Brazil, Columbia, Malaysia, Mexico, the Philippines, and Thailand. We evaluate the cost (direct medical costs and control programme costs) and cost-effectiveness of sustained vector control, outbreak response and/or medical case management, in the presence of a (hypothetical) highly targeted and low cost immunization strategy using a (non-hypothetical) medium-efficacy vaccine. Results Sustained vector control using existing technologies would cost little more than outbreak response, given the associated costs of medical case management. If sustained use of existing or upcoming technologies (of similar price) reduce vector populations by 70–90%, the cost per disability-adjusted life year averted is 2013 US$ 679–1331 (best estimates) relative to no intervention. Sustained vector control could be highly cost-effective even with less effective technologies (50–70% reduction in vector populations) and in the presence of a highly targeted and low cost immunization strategy using a medium-efficacy vaccine. Discussion Economic evaluation of the first-ever dengue vaccine is ongoing. However, even under very optimistic assumptions about a highly targeted and low cost immunization strategy, our results suggest that sustained vector control will continue to play an important role in mitigating the impact of environmental change and urbanization on human health. If additional benefits for the control of other Aedes borne diseases, such as Chikungunya, yellow fever and Zika fever are taken into account, the investment case is even stronger. High-burden endemic countries should proceed to map populations to be covered by sustained vector control. PMID:28806786

Leishmaniosis of companion animals in Europe: an update.

PubMed

Pennisi, Maria Grazia

2015-02-28

Leishmaniosis caused by Leishmania infantum is a vector-borne zoonotic disease endemic in southern Europe, but which is spreading northwards. Millions of dogs, cats and other non-conventional companion animals susceptible to L. infantum, living in European households, may develop a severe disease and contribute to the spread of leishmaniosis because of travelling or re-homing. Dogs are the main reservoir but other new reservoirs have recently been incriminated. Sand flies remain the sole proven vector and non-vectorial transmission has been reported at individual level and in areas where the vector is absent. Clinical disease affects only a proportion of infected dogs and a complex genetic background of immune response is responsible for this susceptibility. There is a wide range of serological and parasitological diagnostic tools available whose cost-effective use depends on a reasoned approach. Clinical response to treatment of sick dogs is variable. Clinical cure is often obtained but clinical recurrence can occur and post-therapy follow up should be maintained life-long. In Europe, vaccination can be combined with individual protection with pyrethroids as part of an integrated approach to prevention. L. infantum is the only species isolated from cats in Europe and xenodiagnosis substantiated that infected cats are infectious for sand flies. Feline infection may be frequent in endemic areas, but prevalence is generally lower than in dogs. When cats are tested by both serological and molecular techniques discordant results are often observed. Feline cases have been reported from endemic areas in Italy, France, Spain and Portugal, but four cases were also diagnosed in Switzerland in cats that had travelled to or been imported from Spain. Half of the cases were diagnosed in cats with impaired immune responses. Clinical manifestations compatible with feline leishmaniosis include lymph node enlargement, skin and mucocutaneous lesions, ocular lesions, chronic gingivostomatitis, hypergammaglobulinemia, and normocytic normochromic anemia. Cats have been empirically treated with some drugs used in dogs. Due to polymorphic clinical picture and the insidious progressive course, leishmaniosis can persist for a long time before dogs or cats are brought to a veterinarian and so diagnosis can be delayed. Exotic or new Leishmania spp. have been reported in humans, animals and vectors in Europe. This changing situation requires attention in Europe for designing epidemiological studies and control measures. Copyright © 2014 Elsevier B.V. All rights reserved.

The evolution of plant virus transmission pathways.

PubMed

Hamelin, Frédéric M; Allen, Linda J S; Prendeville, Holly R; Hajimorad, M Reza; Jeger, Michael J

2016-05-07

The evolution of plant virus transmission pathways is studied through transmission via seed, pollen, or a vector. We address the questions: under what circumstances does vector transmission make pollen transmission redundant? Can evolution lead to the coexistence of multiple virus transmission pathways? We restrict the analysis to an annual plant population in which reproduction through seed is obligatory. A semi-discrete model with pollen, seed, and vector transmission is formulated to investigate these questions. We assume vector and pollen transmission rates are frequency-dependent and density-dependent, respectively. An ecological stability analysis is performed for the semi-discrete model and used to inform an evolutionary study of trade-offs between pollen and seed versus vector transmission. Evolutionary dynamics critically depend on the shape of the trade-off functions. Assuming a trade-off between pollen and vector transmission, evolution either leads to an evolutionarily stable mix of pollen and vector transmission (concave trade-off) or there is evolutionary bi-stability (convex trade-off); the presence of pollen transmission may prevent evolution of vector transmission. Considering a trade-off between seed and vector transmission, evolutionary branching and the subsequent coexistence of pollen-borne and vector-borne strains is possible. This study contributes to the theory behind the diversity of plant-virus transmission patterns observed in nature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Impact of floods induced by extreme precipitation events on public health

NASA Astrophysics Data System (ADS)

Mavroulis, Spyridon; Mavrouli, Maria; Lekkas, Efthymios; Tsakris, Athanassios

2017-04-01

Hydrometeorological disasters comprise the most reported type of natural disaster, and floods account for the majority of disasters in this category in both developed and developing countries. Flooding can lead to extensive morbidity and mortality and pose multiple risks to public health throughout the world. This study involved an extensive and systematic literature review of 124 research publications related to public health impact of 98 floods that occurred globally (Oceania 4, Africa 9, America 22, Europe 24, Asia 39) from 1942 to 2014. The inclusion criteria were literature type comprising journal articles and official reports, natural disaster type including floods induced after extreme precipitation events (accumulation of rainwater in poorly-drained environments, riverine and flash floods), population type including humans, and outcome measure characterized by infectious diseases (ID) incidence increase. The potential post-flood ID are classified into 13 groups including rodent-borne (reported in 38 of the total 98 events, 38.78%), water-borne (33, 33.67%), vector-borne (25, 25.51%), respiratory (19, 19.39%), fecal-oral (14, 14.29%), skin (9, 9.18%), blood-borne (4, 4.08%), eye (3, 3.06%), soil-related (3, 3.06%), ear (2, 2.04%), fungal (1, 1.02%) and wound-borne (1, 1.02%) ID. Based on available age and genre data, it is concluded that the most vulnerable population groups are predominantly young children (age ≤ 5 years) and male. The most fatal post-flood ID are leptospirosis and diarrhea followed by respiratory tract infections. The detected risk factors include (1) poor economic status and living in flood prone areas, (2) destruction of infrastructures, disruption of public utilities and interruption of basic public health services such as vector control programs, (3) direct physical exposure to sewage-polluted flood water, (4) lack of adequate potable water and water-supply from contaminated ponds and tube wells along with lack of distribution of water purification tablets, (5) aggravation of environmental conditions comprising rapid cooling of the environment and heightened humidity, (6) population displacement resulting in densely populated and overcrowded regions, (7) unfavorable living conditions in emergency shelters (8) improper and inadequate sanitation or no access to clean water and sanitation, (9) proliferation and abrupt increase of vector and rodent populations after flooding, (10) contamination of water, damp soil, mud or vegetation caused by rodent urine, dead animals and overflow of latrines. In conclusion, various ID emerge after the flood onset, and outbreaks may result due to the combined effect of several aggravating socio-economic factors and unfavorable environmental conditions. Because of the increased potential for outbreaks after flooding disasters, enhanced public health services and surveillance systems are necessary for the early detection of emerging diseases and outbreaks, and the targeted intervention for disease control.

Mosquito vector-associated microbiota: Metabarcoding bacteria and eukaryotic symbionts across habitat types in Thailand endemic for dengue and other arthropod-borne diseases.

PubMed

Thongsripong, Panpim; Chandler, James Angus; Green, Amy B; Kittayapong, Pattamaporn; Wilcox, Bruce A; Kapan, Durrell D; Bennett, Shannon N

2018-01-01

Vector-borne diseases are a major health burden, yet factors affecting their spread are only partially understood. For example, microbial symbionts can impact mosquito reproduction, survival, and vectorial capacity, and hence affect disease transmission. Nonetheless, current knowledge of mosquito-associated microbial communities is limited. To characterize the bacterial and eukaryotic microbial communities of multiple vector species collected from different habitat types in disease endemic areas, we employed next-generation 454 pyrosequencing of 16S and 18S rRNA amplicon libraries, also known as metabarcoding. We investigated pooled whole adult mosquitoes of three medically important vectors, Aedes aegypti , Ae. albopictus , and Culex quinquefasciatus, collected from different habitats across central Thailand where we previously characterized mosquito diversity. Our results indicate that diversity within the mosquito microbiota is low, with the majority of microbes assigned to one or a few taxa. Two of the most common eukaryotic and bacterial genera recovered ( Ascogregarina and Wolbachia, respectively) are known mosquito endosymbionts with potentially parasitic and long evolutionary relationships with their hosts. Patterns of microbial composition and diversity appeared to differ by both vector species and habitat for a given species, although high variability between samples suggests a strong stochastic element to microbiota assembly. In general, our findings suggest that multiple factors, such as habitat condition and mosquito species identity, may influence overall microbial community composition, and thus provide a basis for further investigations into the interactions between vectors, their microbial communities, and human-impacted landscapes that may ultimately affect vector-borne disease risk.

Increased risk for autochthonous vector-borne infections transmitted by Aedes albopictus in continental Europe.

PubMed

Gossner, Céline M; Ducheyne, Els; Schaffner, Francis

2018-06-01

Autochthonous outbreaks of chikungunya and dengue during the past decade showed that continental Europe is vulnerable to Aedes albopictus -borne infections. Ae. albopictus has spread geographically, resulting in more people exposed to risk. Timely application of adequate mosquito suppression measures may delay, or even prevent, the vector population from crossing the potential epidemic abundance threshold should a pathogen be introduced. Health authorities should be on alert to detect early cases to prevent autochthonous outbreaks.

A virulent babesia bovis strain failed to infect white-tailed deer (Odocoileus virginianus)

USDA-ARS?s Scientific Manuscript database

Wildlife are an important component in the vector-host-pathogen triangle of livestock diseases, as they maintain biological vectors that transmit pathogens and can serve as reservoirs for such infectious pathogens. Babesia bovis is a tick-borne pathogen, vectored by cattle fever ticks, Rhipicephalus...

Arboviral diseases and malaria in Australia, 2012-13: Annual report of the National Arbovirus and Malaria Advisory Committee.

PubMed

Knope, Katrina E; Kurucz, Nina; Doggett, Stephen L; Muller, Mike; Johansen, Cheryl A; Feldman, Rebecca; Hobby, Michaela; Bennett, Sonya; Sly, Angus; Lynch, Stacey; Currie, Bart J; Nicholson, Jay

2016-03-31

This report describes the epidemiology of mosquito-borne diseases of public health importance in Australia during the 2012-13 season (1 July 2012 to 30 June 2013) and includes data from human notifications, sentinel chicken, vector and virus surveillance programs. The National Notifiable Diseases Surveillance System received notifications for 9,726 cases of disease transmitted by mosquitoes during the 2012-13 season. The Australasian alphaviruses Barmah Forest virus and Ross River virus accounted for 7,776 (80%) of total notifications. However, over-diagnosis and possible false positive diagnostic test results for these 2 infections mean that the true burden of infection is likely overestimated, and as a consequence, the case definitions were revised, effective from 1 January 2016. There were 96 notifications of imported chikungunya virus infection. There were 212 notifications of dengue virus infection acquired in Australia and 1,202 cases acquired overseas, with an additional 16 cases for which the place of acquisition was unknown. Imported cases of dengue were most frequently acquired in Indonesia. No locally-acquired malaria was notified during the 2012-13 season, though there were 415 notifications of overseas-acquired malaria. There were no cases of Murray Valley encephalitis virus infection in 2012-13. In 2012-13, arbovirus and mosquito surveillance programs were conducted in most jurisdictions with a risk of vectorborne disease transmission. Surveillance for exotic mosquitoes at the border continues to be a vital part of preventing the spread of mosquito-borne diseases such as dengue to new areas of Australia, and in 2012-13, there were 7 detections of exotic mosquitoes at the border.

Seroprevalence of vector-borne pathogens and molecular detection of Borrelia afzelii in military dogs from Portugal.

PubMed

Alho, Ana Margarida; Pita, Joana; Amaro, Ana; Amaro, Fátima; Schnyder, Manuela; Grimm, Felix; Custódio, Ana Cristina; Cardoso, Luís; Deplazes, Peter; de Carvalho, Luís Madeira

2016-05-10

Canine vector-borne diseases (CVBDs) are increasingly being reported worldwide and represent a serious threat to both animal and public health. Military dogs may constitute a risk group for the agents causing these diseases, as they frequently work outdoors in different areas and are thus exposed to vector arthropods. In order to assess the risk of exposure of this type of dogs, a serological and molecular survey was conducted in military working dogs in Portugal. One hundred apparently healthy dogs were surveyed. Serum samples were tested for antigens of Angiostrongylus vasorum and Dirofilaria immitis; and for antibodies to A. vasorum, Anaplasma spp., Babesia spp., Ehrlichia canis, Leishmania infantum, Rickettsia spp. and Toscana virus. Serum was tested by polymerase chain reaction for Borrelia burgdorferi (sensu lato), with sequencing of the DNA products. Forty-nine per cent of the dogs were seropositive for antibodies against Rickettsia spp., 16 % for Anaplasma spp., 13 % for L. infantum, 7 % for E. canis, 5 % for A. vasorum (including 1 % positive for both antibodies and circulating antigens), 3 % for Babesia spp. and 1 % positive for Toscana virus. B. burgdorferi (s.l.) was detected in eight out of 94 dogs tested (8.5 %) and in three cases (3.2 %) nucleotide sequence analysis showed identity with the genospecies Borrelia afzelii. No positive cases were recorded for D. immitis. Overall, 66 % of the dogs were positive for at least one out of the eight tested CVBD agents, six of which are zoonotic (i.e. Anaplasma spp., Borrelia spp., E. canis, L. infantum, Rickettsia spp. and Toscana virus). Serological specific antibody detection against more than one CVBD agent (including molecular detection of Borrelia spp.) was recorded in 25 % of the dogs, comprising 19 % with positive reaction to two agents, 5 % to three agents and 1 % to four agents. These results reveal a high occurrence of CVBD agents in military working dogs in Portugal and highlight the need to maintain a comprehensive and regular prophylaxis to reduce the contact between working dogs and those pathogens. For the first time in Portugal, B. afzelii DNA was identified in dogs and a dog was found seropositive for antibodies against Toscana virus.

Mosquito vectors and the spread of cancer: an overlooked connection?

PubMed

Benelli, Giovanni; Lo Iacono, Annalisa; Canale, Angelo; Mehlhorn, Heinz

2016-06-01

Mosquitoes (Diptera: Culicidae) represent a key threat for millions of humans and animals worldwide, vectoring important pathogens and parasites, including malaria, dengue, filariasis, and Zika virus. Besides mosquito-borne diseases, cancers figure among the leading causes of mortality worldwide. It is expected that annual cancer cases will rise from 14 million in 2012 to 22 million within the next two decades. Notably, there are few contrasting evidences of the relationship between cancer and mosquito-borne diseases, with special reference to malaria. However, analogies at the cellular level for the two diseases were reported. Recently, a significant association of malaria incidence with all cancer mortality in 50 USA states was highlighted and may be explained by the ability of Plasmodium to induce suppression of the immune system. However, it was hypothesized that Anopheles vectors may transmit obscure viruses linked with cancer development. The possible activation of cancer pathways by mosquito feeding events is not rare. For instance, the hamster reticulum cell sarcoma can be transmitted through the bites of Aedes aegypti by a transfer of tumor cells. Furthermore, mosquito bites may influence human metabolic pathways following different mechanisms, leading to other viral infections and/or oncogenesis. Hypersensitivity to mosquito bites is routed by a unique pathogenic mechanism linking Epstein-Barr virus infection, allergy, and oncogenesis. During dengue virus infection, high viral titers, macrophage infiltration, and tumor necrosis factor alpha production in the local tissues are the three key important events that lead to hemorrhage. Overall, basic epidemiological knowledge on the relationships occurring between mosquito vector activity and the spread of cancer is urgently needed, as well as detailed information about the ability of Culicidae to transfer viruses or tumor cells among hosts over time. Current evidences on nanodrugs with multipotency against mosquito-borne diseases and cancers are reviewed, with peculiar attention to their mechanisms of action.

Canine vector-borne diseases in Brazil

PubMed Central

Dantas-Torres, Filipe

2008-01-01

Canine vector-borne diseases (CVBDs) are highly prevalent in Brazil and represent a challenge to veterinarians and public health workers, since some diseases are of great zoonotic potential. Dogs are affected by many protozoa (e.g., Babesia vogeli, Leishmania infantum, and Trypanosoma cruzi), bacteria (e.g., Anaplasma platys and Ehrlichia canis), and helminths (e.g., Dirofilaria immitis and Dipylidium caninum) that are transmitted by a diverse range of arthropod vectors, including ticks, fleas, lice, triatomines, mosquitoes, tabanids, and phlebotomine sand flies. This article focuses on several aspects (etiology, transmission, distribution, prevalence, risk factors, diagnosis, control, prevention, and public health significance) of CVBDs in Brazil and discusses research gaps to be addressed in future studies. PMID:18691408

Relapsing Fevers: Neglected Tick-Borne Diseases

PubMed Central

Talagrand-Reboul, Emilie; Boyer, Pierre H.; Bergström, Sven; Vial, Laurence; Boulanger, Nathalie

2018-01-01

Relapsing fever still remains a neglected disease and little is known on its reservoir, tick vector and physiopathology in the vertebrate host. The disease occurs in temperate as well as tropical countries. Relapsing fever borreliae are spirochaetes, members of the Borreliaceae family which also contain Lyme disease spirochaetes. They are mainly transmitted by Ornithodoros soft ticks, but some species are vectored by ixodid ticks. Traditionally a Borrelia species is associated with a specific vector in a particular geographical area. However, new species are regularly described, and taxonomical uncertainties deserve further investigations to better understand Borrelia vector/host adaptation. The medical importance of Borrelia miyamotoi, transmitted by Ixodes spp., has recently spawned new interest in this bacterial group. In this review, recent data on tick-host-pathogen interactions for tick-borne relapsing fevers is presented, with special focus on B. miyamotoi. PMID:29670860

Understanding the effect of vector dynamics in epidemic models using center manifold analysis

NASA Astrophysics Data System (ADS)

Rocha, Filipe; Aguiar, Maíra; Souza, Max; Stollenwerk, Nico

2012-09-01

In vector borne diseases the human hosts' epidemiology often acts on a much slower time scales than the one of the mosquitos which transmit the disease as a vector from human to human, due to their vastly different life cycles. We investigate in a model with susceptible (S), infected (I) and recovered (R) humans and susceptible (U) and infected (V) mosquitoes in how far the fast time scale of the mosquito epidemiology can be slaved by the slower human epidemiology, so that for the understanding of human disease data mainly the dynamics of the human time scale is essential and only slightly perturbed by the mosquito dynamics. This analysis of the SIRUV model is qualitatively in agreement with a previously investigated simpler SISUV model, hence a feature of vector-borne diseases in general.

Dengue: recent past and future threats

PubMed Central

Rogers, David J.

2015-01-01

This article explores four key questions about statistical models developed to describe the recent past and future of vector-borne diseases, with special emphasis on dengue: (1) How many variables should be used to make predictions about the future of vector-borne diseases?(2) Is the spatial resolution of a climate dataset an important determinant of model accuracy?(3) Does inclusion of the future distributions of vectors affect predictions of the futures of the diseases they transmit?(4) Which are the key predictor variables involved in determining the distributions of vector-borne diseases in the present and future?Examples are given of dengue models using one, five or 10 meteorological variables and at spatial resolutions of from one-sixth to two degrees. Model accuracy is improved with a greater number of descriptor variables, but is surprisingly unaffected by the spatial resolution of the data. Dengue models with a reduced set of climate variables derived from the HadCM3 global circulation model predictions for the 1980s are improved when risk maps for dengue's two main vectors (Aedes aegypti and Aedes albopictus) are also included as predictor variables; disease and vector models are projected into the future using the global circulation model predictions for the 2020s, 2040s and 2080s. The Garthwaite–Koch corr-max transformation is presented as a novel way of showing the relative contribution of each of the input predictor variables to the map predictions. PMID:25688021

Using the basic reproduction number to assess the effects of climate change in the risk of Chagas disease transmission in Colombia.

PubMed

Cordovez, Juan M; Rendon, Lina Maria; Gonzalez, Camila; Guhl, Felipe

2014-01-01

The dynamics of vector-borne diseases has often been linked to climate change. However the commonly complex dynamics of vector-borne diseases make it very difficult to predict risk based on vector or host distributions. The basic reproduction number (R0) integrates all factors that determine whether a pathogen can establish or not. To obtain R0 for complex vector-borne diseases one can use the next-generation matrix (NGM) approach. We used the NGM to compute R0 for Chagas disease in Colombia incorporating the effect of temperature in some of the transmission routes of Trypanosoma cruzi. We used R0 to generate a risk map of present conditions and a forecast risk map at 20 years from now based on mean annual temperature (data obtained from Worldclim). In addition we used the model to compute elasticity and sensitivity indexes on all model parameters and routes of transmission. We present this work as an approach to indicate which transmission pathways are more critical for disease transmission but acknowledge the fact that results and projections strongly depend on better knowledge of entomological parameters and transmission routes. We concluded that the highest contribution to R0 comes from transmission of the parasites from humans to vectors, which is a surprising result. In addition,parameters related to contacts between human and vectors and the efficiency of parasite transmission between them also show a prominent effect on R0.

Impact of El Niño Southern Oscillation on infectious disease hospitalization risk in the United States.

PubMed

Fisman, David N; Tuite, Ashleigh R; Brown, Kevin A

2016-12-20

Although the global climate is changing at an unprecedented rate, links between weather and infectious disease have received little attention in high income countries. The "El Niño Southern Oscillation" (ENSO) occurs irregularly and is associated with changing temperature and precipitation patterns. We studied the impact of ENSO on infectious diseases in four census regions in the United States. We evaluated infectious diseases requiring hospitalization using the US National Hospital Discharge Survey (1970-2010) and five disease groupings that may undergo epidemiological shifts with changing climate: (i) vector-borne diseases, (ii) pneumonia and influenza, (iii) enteric disease, (iv) zoonotic bacterial disease, and (v) fungal disease. ENSO exposure was based on the Multivariate ENSO Index. Distributed lag models, with adjustment for seasonal oscillation and long-term trends, were used to evaluate the impact of ENSO on disease incidence over lags of up to 12 mo. ENSO was associated more with vector-borne disease [relative risk (RR) 2.96, 95% confidence interval (CI) 1.03-8.48] and less with enteric disease (0.73, 95% CI 0.62-0.87) in the Western region; the increase in vector-borne disease was attributable to increased risk of rickettsioses and tick-borne infectious diseases. By contrast, ENSO was associated with more enteric disease in non-Western regions (RR 1.12, 95% CI 1.02-1.15). The periodic nature of ENSO may make it a useful natural experiment for evaluation of the impact of climatic shifts on infectious disease risk. The impact of ENSO suggests that warmer temperatures and extreme variation in precipitation events influence risks of vector-borne and enteric disease in the United States.

Interpretations and pitfalls in modelling vector-transmitted infections.

PubMed

Amaku, M; Azevedo, F; Burattini, M N; Coutinho, F A B; Lopez, L F; Massad, E

2015-07-01

In this paper we propose a debate on the role of mathematical models in evaluating control strategies for vector-borne infections. Mathematical models must have their complexity adjusted to their goals, and we have basically two classes of models. At one extreme we have models that are intended to check if our intuition about why a certain phenomenon occurs is correct. At the other extreme, we have models whose goals are to predict future outcomes. These models are necessarily very complex. There are models in between these classes. Here we examine two models, one of each class and study the possible pitfalls that may be incurred. We begin by showing how to simplify the description of a complicated model for a vector-borne infection. Next, we examine one example found in a recent paper that illustrates the dangers of basing control strategies on models without considering their limitations. The model in this paper is of the second class. Following this, we review an interesting paper (a model of the first class) that contains some biological assumptions that are inappropriate for dengue but may apply to other vector-borne infections. In conclusion, we list some misgivings about modelling presented in this paper for debate.

Molecular detection of Dirofilaria immitis, Hepatozoon canis, Babesia spp., Anaplasma platys and Ehrlichia canis in dogs on Costa Rica.

PubMed

Wei, Lanjing; Kelly, Patrick; Ackerson, Kate; El-Mahallawy, Heba S; Kaltenboeck, Bernhard; Wang, Chengming

2014-03-01

Although vector-borne diseases are important causes of morbidity and mortality in dogs in tropical areas, there is little information on these conditions in Costa Rica. In PCRs of blood from dogs in Costa Rica, we did not detect DNAs of Rickettsia (R.) felis and Coxiella (C.) burnetii but we did find evidence of infection with Dirofilaria (D.) immitis (9/40, 22.5%), Hepatozoon (H.) canis (15/40, 37.5%), Babesia spp. (10/40, 25%; 2 with B. gibsoni and 8 with B. vogeli), Anaplasma (A.) platys (3/40, 7.5%) and Ehrlichia (E.) canis (20/40, 50%). Nine dogs (22.5%) were free of any vector-borne pathogens while 14 (35%) were infected with a single pathogen, 11 (27.5%) with two, 4 (10%) with three, 1 (2.5%) with four, and 1 (2.5%) with five pathogens. Dogs in Costa Rica are commonly infected with vector-borne agents.

Spatial Risk Assessments Based on Vector-Borne Disease Epidemiologic Data: Importance of Scale for West Nile Virus Disease in Colorado

PubMed Central

Winters, Anna M.; Eisen, Rebecca J.; Delorey, Mark J.; Fischer, Marc; Nasci, Roger S.; Zielinski-Gutierrez, Emily; Moore, Chester G.; Pape, W. John; Eisen, Lars

2010-01-01

We used epidemiologic data for human West Nile virus (WNV) disease in Colorado from 2003 and 2007 to determine 1) the degree to which estimates of vector-borne disease occurrence is influenced by spatial scale of data aggregation (county versus census tract), and 2) the extent of concordance between spatial risk patterns based on case counts versus incidence. Statistical analyses showed that county, compared with census tract, accounted for approximately 50% of the overall variance in WNV disease incidence, and approximately 33% for the subset of cases classified as West Nile neuroinvasive disease. These findings indicate that sub-county scale presentation provides valuable risk information for stakeholders. There was high concordance between spatial patterns of WNV disease incidence and case counts for census tract (83%) but not for county (50%) or zip code (31%). We discuss how these findings impact on practices to develop spatial epidemiologic data for vector-borne diseases and present data to stakeholders. PMID:20439980

International workshop on insecticide resistance in vectors of arboviruses, December 2016, Rio de Janeiro, Brazil.

PubMed

Corbel, Vincent; Fonseca, Dina M; Weetman, David; Pinto, João; Achee, Nicole L; Chandre, Fabrice; Coulibaly, Mamadou B; Dusfour, Isabelle; Grieco, John; Juntarajumnong, Waraporn; Lenhart, Audrey; Martins, Ademir J; Moyes, Catherine; Ng, Lee Ching; Raghavendra, Kamaraju; Vatandoost, Hassan; Vontas, John; Muller, Pie; Kasai, Shinji; Fouque, Florence; Velayudhan, Raman; Durot, Claire; David, Jean-Philippe

2017-06-02

Vector-borne diseases transmitted by insect vectors such as mosquitoes occur in over 100 countries and affect almost half of the world's population. Dengue is currently the most prevalent arboviral disease but chikungunya, Zika and yellow fever show increasing prevalence and severity. Vector control, mainly by the use of insecticides, play a key role in disease prevention but the use of the same chemicals for more than 40 years, together with the dissemination of mosquitoes by trade and environmental changes, resulted in the global spread of insecticide resistance. In this context, innovative tools and strategies for vector control, including the management of resistance, are urgently needed. This report summarizes the main outputs of the first international workshop on Insecticide resistance in vectors of arboviruses held in Rio de Janeiro, Brazil, 5-8 December 2016. The primary aims of this workshop were to identify strategies for the development and implementation of standardized insecticide resistance management, also to allow comparisons across nations and across time, and to define research priorities for control of vectors of arboviruses. The workshop brought together 163 participants from 28 nationalities and was accessible, live, through the web (> 70,000 web-accesses over 3 days).

Autochthonous canine leishmaniasis in Romania: neglected or (re)emerging?

PubMed Central

2014-01-01

Canine leishmaniasis is a vector-borne zoonotic disease caused by the protozoan parasite Leishmania infantum. In Romania between 1955 and 2013, no cases of human autochthonous visceral leishmaniasis were reported. Data regarding canine leishmaniasis is similarly scarce. Since the first report of clinical autochthonous canine leishmaniasis in 1935, there were only three sporadic reports of positive dogs all without any clinical signs. Our study reports the first clinical case of autochthonous canine leishmaniasis in the last 80 years, stressing the importance of a targeted surveillance of Leishmania infection, as infected dogs act as the primary reservoir for zoonotic visceral leishmaniasis. PMID:24684827

Illnesses on the Rise From Mosquito, Tick, and Flea Bites

MedlinePlus

... gets sick has a vector-borne disease, like dengue, Zika, Lyme, or plague. Between 2004 and 2016, ... Mosquito-borne diseases California serogroup viruses Chikungunya virus Dengue viruses Eastern equine encephalitis virus Malaria plasmodium St. ...

Molecular identification of vertebrate and hemoparasite DNA within mosquito blood meals from eastern North Dakota.

PubMed

Mehus, Joseph O; Vaughan, Jefferson A

2013-11-01

To understand local transmission of vector-borne diseases, it is important to identify potential vectors, characterize their host feeding patterns, and determine if vector-borne pathogens are circulating within the region. This study simultaneously investigated these aspects of disease transmission by collecting engorged mosquitoes within two rural study sites in the central Red River Valley of North Dakota. Mosquitoes were identified, midguts were excised, and the blood was expelled from the midguts. DNA was extracted from blood meals and subjected to PCR and direct sequencing to identify the vertebrate origin of the blood. Using different primer sets, PCR was used to screen for two types of vector-borne pathogens, filarioid nematodes and hemosporidian parasites. White-tailed deer were the primary source of blood meals for the eight aedine mosquito species collected. None of the 288 deer-derived blood meals contained filarioid or hemosporidian DNA. In contrast, 18 of 32 Culex tarsalis and three of three Cx. pipiens blood meals contained avian blood, representing eight different species of birds. Of 24 avian-derived blood meals examined, 12 contained Plasmodium DNA, three of which also contained Leucocytozoon DNA (i.e., dual infection). Potential confounding effects resulting from parasite acquisition and development from previous blood meals (e.g., oocysts) were eliminated because host blood had been removed from the midguts prior to DNA extraction. Thus, specific parasite lineages/species could be unequivocally linked to specific vertebrate species. By combining mosquito identification with molecular techniques for identifying blood meal source and pathogens, a relatively small sample of engorged mosquitoes yielded important new information about mosquito feeding patterns and hemosporidia infections in birds. Thorough analyses of wild-caught engorged mosquitoes and other arthropods represent a powerful tool in understanding the local transmission of vector-borne and zoonotic diseases.

Molecular Identification of Vertebrate and Hemoparasite DNA Within Mosquito Blood Meals From Eastern North Dakota

PubMed Central

Vaughan, Jefferson A.

2013-01-01

Abstract To understand local transmission of vector-borne diseases, it is important to identify potential vectors, characterize their host feeding patterns, and determine if vector-borne pathogens are circulating within the region. This study simultaneously investigated these aspects of disease transmission by collecting engorged mosquitoes within two rural study sites in the central Red River Valley of North Dakota. Mosquitoes were identified, midguts were excised, and the blood was expelled from the midguts. DNA was extracted from blood meals and subjected to PCR and direct sequencing to identify the vertebrate origin of the blood. Using different primer sets, PCR was used to screen for two types of vector-borne pathogens, filarioid nematodes and hemosporidian parasites. White-tailed deer were the primary source of blood meals for the eight aedine mosquito species collected. None of the 288 deer-derived blood meals contained filarioid or hemosporidian DNA. In contrast, 18 of 32 Culex tarsalis and three of three Cx. pipiens blood meals contained avian blood, representing eight different species of birds. Of 24 avian-derived blood meals examined, 12 contained Plasmodium DNA, three of which also contained Leucocytozoon DNA (i.e., dual infection). Potential confounding effects resulting from parasite acquisition and development from previous blood meals (e.g., oocysts) were eliminated because host blood had been removed from the midguts prior to DNA extraction. Thus, specific parasite lineages/species could be unequivocally linked to specific vertebrate species. By combining mosquito identification with molecular techniques for identifying blood meal source and pathogens, a relatively small sample of engorged mosquitoes yielded important new information about mosquito feeding patterns and hemosporidia infections in birds. Thorough analyses of wild-caught engorged mosquitoes and other arthropods represent a powerful tool in understanding the local transmission of vector-borne and zoonotic diseases. PMID:24107213

Integrated pest management and allocation of control efforts for vector-borne diseases

USGS Publications Warehouse

Ginsberg, H.S.

2001-01-01

Applications of various control methods were evaluated to determine how to integrate methods so as to minimize the number of human cases of vector-borne diseases. These diseases can be controlled by lowering the number of vector-human contacts (e.g., by pesticide applications or use of repellents), or by lowering the proportion of vectors infected with pathogens (e.g., by lowering or vaccinating reservoir host populations). Control methods should be combined in such a way as to most efficiently lower the probability of human encounter with an infected vector. Simulations using a simple probabilistic model of pathogen transmission suggest that the most efficient way to integrate different control methods is to combine methods that have the same effect (e.g., combine treatments that lower the vector population; or combine treatments that lower pathogen prevalence in vectors). Combining techniques that have different effects (e.g., a technique that lowers vector populations with a technique that lowers pathogen prevalence in vectors) will be less efficient than combining two techniques that both lower vector populations or combining two techniques that both lower pathogen prevalence, costs being the same. Costs of alternative control methods generally differ, so the efficiency of various combinations at lowering human contact with infected vectors should be estimated at available funding levels. Data should be collected from initial trials to improve the effects of subsequent interventions on the number of human cases.

Encephalitis, Ontario, Canada, 2002–2013

PubMed Central

Parpia, Alyssa S.; Li, Ye; Chen, Cynthia; Dhar, Badal

2016-01-01

Encephalitis, a brain inflammation leading to severe illness and often death, is caused by >100 pathogens. To assess the incidence and trends of encephalitis in Ontario, Canada, we obtained data on 6,463 Ontario encephalitis hospitalizations from the hospital Discharge Abstract Database for April 2002–December 2013 and analyzed these data using multiple negative binomial regression. The estimated crude incidence of all-cause encephalitis in Ontario was ≈4.3 cases/100,000 persons/year. Incidence rates for infants <1 year of age and adults >65 years were 3.9 and 3.0 times that of adults 20–44 years of age, respectively. Incidence peaks during August–September in 2002 and 2012 resulted primarily from encephalitis of unknown cause and viral encephalitis. Encephalitis occurred more frequently in older age groups and less frequently in women in Ontario when compared to England, but despite differences in population, vector-borne diseases, climate, and geography, the epidemiology was overall remarkably similar in the two regions. PMID:26890626

Host structural carbohydrate induces vector transmission of a bacterial plant pathogen.

PubMed

Killiny, Nabil; Almeida, Rodrigo P P

2009-12-29

Many insect-borne pathogens have complex life histories because they must colonize both hosts and vectors for successful dissemination. In addition, the transition from host to vector environments may require changes in gene expression before the pathogen's departure from the host. Xylella fastidiosa is a xylem-limited plant-pathogenic bacterium transmitted by leafhopper vectors that causes diseases in a number of economically important plants. We hypothesized that factors of host origin, such as plant structural polysaccharides, are important in regulating X. fastidiosa gene expression and mediating vector transmission of this pathogen. The addition of pectin and glucan to a simple defined medium resulted in dramatic changes in X. fastidiosa's phenotype and gene-expression profile. Cells grown in the presence of pectin became more adhesive than in other media tested. In addition, the presence of pectin and glucan in media resulted in significant changes in the expression of several genes previously identified as important for X. fastidiosa's pathogenicity in plants. Furthermore, vector transmission of X. fastidiosa was induced in the presence of both polysaccharides. Our data show that host structural polysaccharides mediate gene regulation in X. fastidiosa, which results in phenotypic changes required for vector transmission. A better understanding of how vector-borne pathogens transition from host to vector, and vice versa, may lead to previously undiscovered disease-control strategies.

Resting and feeding preferences of Anopheles stephensi in an urban setting, perennial for malaria.

PubMed

Thomas, Shalu; Ravishankaran, Sangamithra; Justin, N A Johnson Amala; Asokan, Aswin; Mathai, Manu Thomas; Valecha, Neena; Montgomery, Jacqui; Thomas, Matthew B; Eapen, Alex

2017-03-10

The Indian city of Chennai is endemic for malaria and the known local malaria vector is Anopheles stephensi. Plasmodium vivax is the predominant malaria parasite species, though Plasmodium falciparum is present at low levels. The urban ecotype of malaria prevails in Chennai with perennial transmission despite vector surveillance by the Urban Malaria Scheme (UMS) of the National Vector Borne Disease Control Programme (NVBDCP). Understanding the feeding and resting preferences, together with the transmission potential of adult vectors in the area is essential in effective planning and execution of improved vector control measures. A yearlong survey was carried out in cattle sheds and human dwellings to check the resting, feeding preferences and transmission potential of An. stephensi. The gonotrophic status, age structure, resting and host seeking preferences were studied. The infection rate in An. stephensi and Anopheles subpictus were analysed by circumsporozoite ELISA (CS-ELISA). Adult vectors were found more frequently and at higher densities in cattle sheds than human dwellings. The overall Human Blood Index (HBI) was 0.009 indicating the vectors to be strongly zoophilic. Among the vectors collected from human dwellings, 94.2% were from thatched structures and the remaining 5.8% from tiled and asbestos structures. 57.75% of the dissected vectors were nulliparous whereas, 35.83% were monoparous and the rest 6.42% biparous. Sporozoite positivity rate was 0.55% (4/720) and 1.92% (1/52) for An. stephensi collected from cattle sheds and human dwellings, respectively. One adult An. subpictus (1/155) was also found to be infected with P. falciparum. Control of the adult vector populations can be successful only by understanding the resting and feeding preferences. The present study indicates that adult vectors predominantly feed on cattle and cattle sheds are the preferred resting place, possibly due to easy availability of blood meal source and lack of any insecticide or repellent pressure. Hence targeting these resting sites with cost effective, socially acceptable intervention tools, together with effective larval source management to reduce vector breeding, could provide an improved integrated vector management strategy to help drive down malaria transmission and assist in India's plan to eliminate malaria by 2030.

[Zoonotic diseases caused by bacteria of the genus Bartonella genus: new reservoirs ? New vectors?].

PubMed

Chomel, Bruno B; Boulouis, Henri-Jean

2005-03-01

Domestic animals and wildlife represent a large reservoir for bartonellae, at least eight species or subspecies of which have been reported to cause zoonotic infections. In addition, numerous orphan clinical syndromes are now being attributed to Bartonella henselae infection. Many mammalian species, including cats, dogs, rodents and ruminants are the main bartonellae reservoirs. Cats are the main reservoir for B. henselae. It appears that domestic dogs, at least in non tropical regions, are more likely to be accidental hosts than reservoirs, and constitute excellent sentinels for human infections. Bartonellae are vector-borne bacteria. The mode of B. henselae transmission by cat fleas is now better understood, but new potential vectors have recently been identified, including ticks and biting flies. This articles summarizes current knowledge of the etiology, new clinical features and epidemiological characteristics of these emerging zoonoses.

Vector-Host Interactions of Culiseta melanura in a Focus of Eastern Equine Encephalitis Virus Activity in Southeastern Virginia.

PubMed

Molaei, Goudarz; Armstrong, Philip M; Abadam, Charles F; Akaratovic, Karen I; Kiser, Jay P; Andreadis, Theodore G

2015-01-01

Eastern equine encephalitis virus (EEEV) causes a highly pathogenic mosquito-borne zoonosis that is responsible for sporadic outbreaks of severe illness in humans and equines in the eastern USA. Culiseta (Cs.) melanura is the primary vector of EEEV in most geographic regions but its feeding patterns on specific avian and mammalian hosts are largely unknown in the mid-Atlantic region. The objectives of our study were to: 1) identify avian hosts of Cs. melanura and evaluate their potential role in enzootic amplification of EEEV, 2) assess spatial and temporal patterns of virus activity during a season of intense virus transmission, and 3) investigate the potential role of Cs. melanura in epidemic/epizootic transmission of EEEV to humans and equines. Accordingly, we collected mosquitoes at 55 sites in Suffolk, Virginia in 2013, and identified the source of blood meals in engorged mosquitoes by nucleotide sequencing PCR products of the mitochondrial cytochrome b gene. We also examined field-collected mosquitoes for evidence of infection with EEEV using Vector Test, cell culture, and PCR. Analysis of 188 engorged Cs. melanura sampled from April through October 2013 indicated that 95.2%, 4.3%, and 0.5% obtained blood meals from avian, mammalian, and reptilian hosts, respectively. American Robin was the most frequently identified host for Cs. melanura (42.6% of blood meals) followed by Northern Cardinal (16.0%), European Starling (11.2%), Carolina Wren (4.3%), and Common Grackle (4.3%). EEEV was detected in 106 mosquito pools of Cs. melanura, and the number of virus positive pools peaked in late July with 22 positive pools and a Maximum Likelihood Estimation (MLE) infection rate of 4.46 per 1,000 mosquitoes. Our findings highlight the importance of Cs. melanura as a regional EEEV vector based on frequent feeding on virus-competent bird species. A small proportion of blood meals acquired from mammalian hosts suggests the possibility that this species may occasionally contribute to epidemic/epizootic transmission of EEEV.

Survey of vector-borne agents in feral cats and first report of Babesia gibsoni in cats on St Kitts, West Indies.

PubMed

Kelly, Patrick John; Köster, Liza; Li, Jing; Zhang, Jilei; Huang, Ke; Branford, Gillian Carmichael; Marchi, Silvia; Vandenplas, Michel; Wang, Chengming

2017-11-13

As there is little data on vector-borne diseases of cats in the Caribbean region and even around the world, we tested feral cats from St Kitts by PCR to detect infections with Babesia, Ehrlichia and spotted fever group Rickettsia (SFGR) and surveyed them for antibodies to Rickettsia rickettsii and Ehrlichia canis. Whole blood was collected from apparently healthy feral cats during spay/ neuter campaigns on St Kitts in 2011 (N = 68) and 2014 (N = 52). Sera from the 52 cats from 2014 were used to detect antibodies to Ehrlichia canis and Rickettsia rickettsii using indirect fluorescent antibody tests and DNA extracted from whole blood of a total of 119 cats (68 from 2011, and 51 from 2014) was used for PCRs for Babesia, Ehrlichia and Rickettsia. We could not amplify DNA of SFG Rickettsia in any of the samples but found DNA of E. canis in 5% (6/119), Babesia vogeli in 13% (15/119), Babesia gibsoni in 4% (5/119), mixed infections with B. gibsoni and B. vogeli in 3% (3/119), and a poorly characterized Babesia sp. in 1% (1/119). Overall, 10% of the 52 cats we tested by IFA for E. canis were positive while 42% we tested by indirect fluorescent antibody (IFA) for R. rickettsii antigens were positive. Our study provides the first evidence that cats can be infected with B. gibsoni and also indicates that cats in the Caribbean may be commonly exposed to other vector-borne agents including SFGR, E. canis and B. vogeli. Animal health workers should be alerted to the possibility of clinical infections in their patients while public health workers should be alerted to the possibility that zoonotic SFGR are likely circulating in the region.

Powassan Virus-A New Reemerging Tick-Borne Disease.

PubMed

Fatmi, Syed Soheb; Zehra, Rija; Carpenter, David O

2017-01-01

Powassan virus is a neurovirulent flavivirus consisting of two lineages causing meningoencephalitis. It is the only member of the tick-borne encephalitis serogroup which is present in mainland North America. With a total number of 27 cases from 1958 to 1998 and 98 cases from 1999 to 2016, reported cases have increased by 671% over the last 18 years. Powassan infection is transmitted by different tick species in different geographical regions. Ixodes scapularis is the primary vector that transmits the virus on the East Coast of US and Ixodes cookei in the Midwest and Canada, while Hemaphysalis longicornis is the vector in Russia. Powassan has no singular pathognomonic finding and presents with a wide spectrum of symptoms including severe neurological symptoms. The clinical challenge lies within the management of the disease as there is no standard diagnostic protocol and most cases are only diagnosed after a patient goes through an extensive workup for other infectious disease. The diagnosis is established by a combination of imaging and serologic tests. In case of Powassan meningoencephalitis, computed tomography scan and magnetic resonance imaging show vascular insults, which are also seen in cases of tick-borne encephalitis virus, another flavivirus of medical importance. Serologic tests are the gold standard for diagnosis, although testing is not widely available and only state health departments and Center for Disease Control and Prevention can perform Powassan-specific IgM antibody testing utilizing enzyme-linked immunosorbent assay and immunofluorescence antibody. Powassan is also of veterinary medical importance. Wildlife animals act as a reservoir to the pathogens, hence possessing threat to humans and domestic animals. This review highlights Powassan's neurotropic presentation, epidemiology, diagnostic challenges, and prevalence. Strong emphasis is placed on establishing diagnostic protocols, widespread Powassan-specific IgM testing, role of the vector in disease presentation, and necessary preventive research.

Rodent-borne diseases and their public health importance in Iran.

PubMed

Rabiee, Mohammad Hasan; Mahmoudi, Ahmad; Siahsarvie, Roohollah; Kryštufek, Boris; Mostafavi, Ehsan

2018-04-01

Rodents are reservoirs and hosts for several zoonotic diseases such as plague, leptospirosis, and leishmaniasis. Rapid development of industry and agriculture, as well as climate change throughout the globe, has led to change or increase in occurrence of rodent-borne diseases. Considering the distribution of rodents throughout Iran, the aim of this review is to assess the risk of rodent-borne diseases in Iran. We searched Google Scholar, PubMed, Science Direct, Scientific Information Database (SID), and Magiran databases up to September 2016 to obtain articles reporting occurrence of rodent-borne diseases in Iran and extract information from them. Out of 70 known rodent-borne diseases, 34 were reported in Iran: 17 (50%) parasitic diseases, 13 (38%) bacterial diseases, and 4 (12%) viral diseases. Twenty-one out of 34 diseases were reported from both humans and rodents. Among the diseases reported in the rodents of Iran, plague, leishmaniasis, and hymenolepiasis were the most frequent. The most infected rodents were Rattus norvegicus (16 diseases), Mus musculus (14 diseases), Rattus rattus (13 diseases), Meriones persicus (7 diseases), Apodemus spp. (5 diseases), Tatera indica (4 diseases), Meriones libycus (3 diseases), Rhombomys opimus (3 diseases), Cricetulus migratorius (3 diseases), and Nesokia indica (2 diseases). The results of this review indicate the importance of rodent-borne diseases in Iran. Considering notable diversity of rodents and their extensive distribution throughout the country, it is crucial to pay more attention to their role in spreading infectious diseases for better control of the diseases.

Climate Change Effects: Issues for International and US National Security

DTIC Science & Technology

2009-07-01

impacts such as heat waves, major concerns are significant spreading of conditions for vector-borne diseases, such as dengue fever and malaria, and...U.S. national directives and strategic-level documents, and notable reports on specific climate change impacts or especially vulnerable regions ...add to tensions even in stable world regions . There is greater potential for failed states and political instability. Climate change acts as a

Ticks

USGS Publications Warehouse

Ginsberg, H.S.; Faulde, M.K.

2008-01-01

The most common vector-borne diseases in both Europe and North America are transmitted by ticks. Lyme borreliosis (LB), a tick-borne bacterial zoonosis, is the most highly prevalent. Other important tick-borne diseases include TBE (tick-borne encephalitis) and Crimean-Congo haemorrhagic fever in Europe, Rocky Mountain spotted fever (RMSF) in North America, and numerous less common tick-borne bacterial, viral, and protozoan diseases on both continents. The major etiological agent of LB is Borrelia burgdorferi in North America, while in Europe several related species of Borrelia can also cause human illness. These Borrelia genospecies differ in clinical manifestations, ecology (for example, some have primarily avian and others primarily mammalian reservoirs), and transmission cycles, so the epizootiology of LB is more complex in Europe than in North America. Ticks dwell predominantly in woodlands and meadows, and in association with animal hosts, with only limited colonization of human dwellings by a few species. Therefore, suburbanization has contributed substantially to the increase in tick-borne disease transmission in North America by fostering increased exposure of humans to tick habitat. The current trend toward suburbanization in Europe could potentially result in similar increases in transmission of tick-borne diseases. Incidence of tick-borne diseases can be lowered by active public education campaigns, targeted at the times and places of greatest potential for encounter between humans and infected ticks. Similarly, vaccines (e.g., against TBE) are most effective when made available to people at greatest risk, and for high-prevalence diseases such as LB. Consultation with vector-borne disease experts during the planning stages of new human developments can minimize the potential for residents to encounter infected ticks (e.g., by appropriate dwelling and landscape design). Furthermore, research on tick vectors, pathogens, transmission ecology, and on geographic distribution, spread, and management of tick-borne diseases can lead to innovative and improved methods to lower the incidence of these diseases. Surveillance programs to monitor the distribution and spread of ticks, associated pathogens, and their reservoirs, can allow better-targeted management efforts, and provide data to assess effectiveness and to improve management programs.

Hydroclimatic Assessment of West Nile Virus Occurrence Across Continental US

NASA Astrophysics Data System (ADS)

Billian, H. E.; Jutla, A.; Colwell, R. R.

2014-12-01

West Nile virus (WNV) is the most widely infections from arbovirus in mid-latitudes, having reached the Western Hemisphere in 1999. As a vector-borne disease, WNV is primarily spread by mosquitoes; the disease is predominantly found in tropical and temperate regions of the world, and is now considered an endemic pathogen in the United States, Africa, Asia, Australia, the Middle East, and Europe. Environmental processes play a vital role in the trigger of WNV. Here, using logistical regression models, we quantified relationships between hydroclimatic processes and mosquito abundance for WNV across the continental USA using precipitation and temperature at different spatial and temporal scales. It will be shown that reported cases of this disease are more prevalent during spring and summer months in the entire country, when there is more precipitation and higher surface air temperatures for 2003 to 2013. The key impacts of this research are those related to the improvement of human health, and a means to predict mosquito breeding patterns long term as they relate to the prevalence of vector-borne illnesses.

Cascading effect of economic globalization on human risks of scrub typhus and tick-borne rickettsial diseases.

PubMed

Kuo, Chi-Chien; Huang, Jing-Lun; Shu, Pei-Yun; Lee, Pei-Lung; Kelt, Douglas A; Wang, Hsi-Chieh

2012-09-01

The increase in global travel and trade has facilitated the dissemination of disease vectors. Globalization can also indirectly affect vector-borne diseases through the liberalization of cross-border trade, which has far-reaching, worldwide effects on agricultural practices and may in turn influence vectors through the modification of the ecological landscape. While the cascading effect of economic globalization on vector-borne diseases, sometimes acting synergistically with regional agricultural policy, could be substantial and have significant economic, agricultural, and public health implications, research into this remains very limited. We evaluated how abandonment of rice paddies in Taiwan after joining the World Trade Organization, along with periodic plowing, an agricultural policy to reduce farm pests in abandoned fields can unexpectedly influence risks to diseases transmitted by ticks and chiggers (larval trombiculid mites), which we collected from their small-mammal hosts. Sampling was limited to abandoned (fallow) and plowed fields due to the challenge of trapping small mammals in flooded rice paddies. Striped field mice (Apodemus agrarius) are the main hosts for both vectors. They harbored six times more ticks and three times more chiggers in fallow than in plowed plots. The proportion of ticks infected with Rickettsia spp. (etiologic agent of spotted fever) was three times higher in fallow plots, while that of Orientia tsutsugamushi (scrub typhus) in chiggers was similar in both treatments. Fallow plots had more ground cover and higher vegetation than plowed ones. Moreover, ticks and chiggers in both field types were dominated by species known to infest humans. Because ticks and chiggers should exhibit very low survival in flooded rice paddies, we propose that farm abandonment in Taiwan, driven by globalization, may have inadvertently led to increased risks of spotted fever and scrub typhus. However, periodic plowing can unintentionally mitigate vector burdens. Economic globalization can have unexpected consequences on disease risk through modification of the agricultural landscape, but the outcome may also be influenced by agricultural policies, calling for further research on vector-borne diseases and their control from broader perspectives.

Principal climatic and edaphic determinants of Culicoides biting midge abundance during the 2007-2008 bluetongue epidemic in the Netherlands, based on OVI light trap data.

PubMed

Scolamacchia, F; VAN DEN Broek, J; Meiswinkel, R; Heesterbeek, J A P; Elbers, A R W

2014-06-01

Palaearctic Culicoides midges (Diptera: Ceratopogonidae) represent a vital link in the northward advance of certain arboviral pathogens of livestock such as that caused by bluetongue virus. The effects of relevant ecological factors on weekly Culicoides vector abundances during the bluetongue virus serotype 8 epidemics in the Netherlands in 2007 and 2008 were quantified within a hurdle modelling framework. The relative role of meteorological parameters showed a broadly consistent association across species, with larger catches linked to temperature-related variables and lower wind speed. Moreover, vector abundance was found to be influenced by edaphic factors, likely related to species-specific breeding habitat preferences that differed markedly amongst some species. This is the first study on Culicoides vector species in the Netherlands identified during an entomological surveillance programme, in which an attempt is made to pinpoint the factors that influence midge abundance levels. In addition to providing key inputs into risk-mitigating tools for midge-borne pathogens and disease transmission models, the adoption of methods that explicitly address certain features of abundance datasets (frequent zero-count observations and over-dispersion) helped enhance the robustness of the ecological analysis. © 2013 The Royal Entomological Society.

Wolbachia: A biological control strategy against arboviral diseases.

PubMed

Mohanty, Ipsita; Rath, Animesha; Mahapatra, Namita; Hazra, Rupenangshu K

2016-01-01

Vector-borne diseases particularly those transmitted by mosquitoes like Dengue are among the leading causes of mortality and morbidity in human population. There are no effective vaccines or treatment against dengue fever till date and the control methods are limited. So, new approaches are urgently in need to reverse these trends. Vector control is currently the primary intervention tool. Strategies that reduce or block pathogen transmission by mosquitoes have been proposed as a means of augmenting current control measures to reduce the growing burden of vector-borne diseases. Wolbachia an endosymbiont of arthropod vectors is being explored as a novel ecofriendly control strategy. Studies in Drosophila have shown that Wolbachia can confer resistance to diverse RNA viruses and protect flies from virus-induced mortality. This review was focused on biology of the Wolbachia and its implication as a control measure for arboviral diseases mainly Dengue and Chikungunya.

Vector-borne parasitic zoonoses: emerging scenarios and new perspectives.

PubMed

Colwell, Douglas D; Dantas-Torres, Filipe; Otranto, Domenico

2011-11-24

Changing climate is not the only driver for alterations in the dynamic interaction between arthropod vectors of zoonotic parasites and their hosts, including humans. A suite of other factors ranging from urbanization and deforestation to changing demographics in both developing and developed countries, the impact of the recent economic crisis, increased global movement of people and animals and follow-on effects of major catastrophes. This article reviews the most important vector-borne parasites of zoonotic concern that are changing/expanding their distribution patterns in both endemic and/or previously non-endemic areas. We include the discussion of the changing aspects of malaria, leishmaniasis, babesiosis, Chagas disease as well as of some spirurid and filarioid nematodes. Copyright © 2011. Published by Elsevier B.V.

[The fourth horseman: The yellow fever].

PubMed

Vallejos-Parás, Alfonso; Cabrera-Gaytán, David Alejandro

2017-01-01

Dengue virus three, Chikunguya and Zika have entered the national territory through the south of the country. Cases and outbreaks of yellow fever have now been identified in the Americas where it threatens to expand. Although Mexico has a robust epidemiological surveillance system for vector-borne diseases, our country must be alert in case of its possible introduction into the national territory. This paper presents theoretical assumptions based on factual data on the behavior of yellow fever in the Americas, as well as reflections on the epidemiological surveillance of vector-borne diseases.

The Challenges and Advances in Diagnosis of Vector-Borne Diseases: Where Do We Stand?

PubMed

Kuleš, Josipa; Potocnakova, Lenka; Bhide, Katarina; Tomassone, Laura; Fuehrer, Hans-Peter; Horvatić, Anita; Galan, Asier; Guillemin, Nicolas; Nižić, Petra; Mrljak, Vladimir; Bhide, Mangesh

2017-05-01

Vector-borne diseases (VBD) are of major importance to human and animal health. In recent years, VBD have been emerging or re-emerging in many geographical areas, alarming new disease threats and economic losses. The precise diagnosis of many of these diseases still remains a major challenge because of the lack of comprehensive data available on accurate and reliable diagnostic methods. Here, we conducted a systematic and in-depth review of the former, current, and upcoming techniques employed for the diagnosis of VBD.

Use of Bibliometric Analysis to Assess the Scientific Productivity and Impact of the Global Emerging Infections Surveillance and Response System Program, 2006-2012.

PubMed

Reaves, Erik J; Valle, Ruben; Chandrasekera, Ruvani M; Soto, Giselle; Burke, Ronald L; Cummings, James F; Bausch, Daniel G; Kasper, Matthew R

2017-05-01

Scientific publication in academic literature is a key venue in which the U.S. Department of Defense's Global Emerging Infections Surveillance and Response System (GEIS) program disseminates infectious disease surveillance data. Bibliometric analyses are tools to evaluate scientific productivity and impact of published research, yet are not routinely used for disease surveillance. Our objective was to incorporate bibliometric indicators to measure scientific productivity and impact of GEIS-funded infectious disease surveillance, and assess their utility in the management of the GEIS surveillance program. Metrics on GEIS program scientific publications, project funding, and countries of collaborating institutions from project years 2006 to 2012 were abstracted from annual reports and program databases and organized by the six surveillance priority focus areas: respiratory infections, gastrointestinal infections, febrile and vector-borne infections, antimicrobial resistance, sexually transmitted infections, and capacity building and outbreak response. Scientific productivity was defined as the number of scientific publications in peer-reviewed literature derived from GEIS-funded projects. Impact was defined as the number of citations of a GEIS-funded publication by other peer-reviewed publications, and the Thomson Reuters 2-year journal impact factor. Indicators were retrieved from the Web of Science and Journal Citation Report. To determine the global network of international collaborations between GEIS partners, countries were organized by the locations of collaborating institutions. Between 2006 and 2012, GEIS distributed approximately US $330 million to support 921 total projects. On average, GEIS funded 132 projects (range 96-160) with $47 million (range $43 million-$53 million), annually. The predominant surveillance focus areas were respiratory infections with 317 (34.4%) projects and $225 million, and febrile and vector-borne infections with 274 (29.8%) projects and $45 million. The number of annual respiratory infections-related projects peaked in 2006 and 2009. The number of febrile and vector-borne infections projects increased from 29 projects in 2006 to 58 in 2012. There were 651 articles published in 147 different peer-reviewed journals, with an average Thomson Reuters 2-year journal impact factor of 4.2 (range 0.3-53.5). On average, 93 articles were published per year (range 67-117) with $510,000 per publication. Febrile and vector-borne, respiratory, and gastrointestinal infections had 287, 167, and 73 articles published, respectively. Of the 651 articles published, 585 (89.9%) articles were cited at least once (range 1-1,045). Institutions from 90 countries located in all six World Health Organization regions collaborated with surveillance projects. These findings summarize the GEIS-funded surveillance portfolio between 2006 and 2012, and demonstrate the scientific productivity and impact of the program in each of the six disease surveillance priority focus areas. GEIS might benefit from further financial investment in both the febrile and vector-borne and sexually transmitted infections surveillance priority focus areas and increasing peer-reviewed publications of surveillance data derived from respiratory infections projects. Bibliometric indicators are useful to measure scientific productivity and impact in surveillance systems; and this methodology can be utilized as a management tool to assess future changes to GEIS surveillance priorities. Additional metrics should be developed when peer-reviewed literature is not used to disseminate noteworthy accomplishments. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

Land-Use Change and Emerging Infectious Disease on an Island Continent

PubMed Central

McFarlane, Rosemary A.; Sleigh, Adrian C.; McMichael, Anthony J.

2013-01-01

A more rigorous and nuanced understanding of land-use change (LUC) as a driver of emerging infectious disease (EID) is required. Here we examine post hunter-gatherer LUC as a driver of infectious disease in one biogeographical region with a compressed and documented history—continental Australia. We do this by examining land-use and native vegetation change (LUCC) associations with infectious disease emergence identified through a systematic (1973–2010) and historical (1788–1973) review of infectious disease literature of humans and animals. We find that 22% (20) of the systematically reviewed EIDs are associated with LUCC, most frequently where natural landscapes have been removed or replaced with agriculture, plantations, livestock or urban development. Historical clustering of vector-borne, zoonotic and environmental disease emergence also follows major periods of extensive land clearing. These advanced stages of LUCC are accompanied by changes in the distribution and density of hosts and vectors, at varying scales and chronology. This review of infectious disease emergence in one continent provides valuable insight into the association between accelerated global LUC and concurrent accelerated infectious disease emergence. PMID:23812027

[Crimean-Congo Hemorrhagic Fever].

PubMed

Güneş, Turabi

2006-07-01

Crimean-Congo Hemorrhagic Fever (CCHF) virus is a tick-borne virus, which is a member of Bunyaviridae family, Nairovirus genus. CCHF virus has been isolated from 31 different tick species so far, and genus Hyalomma includes the basic vectors of which H. anatolicum, H. marginatum, H. detritum, H. dromedarii, H. excavatum and H. turanicum are frequently found in the geography in which Turkey takes place. The virus is transmitted via the bite of infected ticks or direct contact with CCHF infected patients and the products of infected animals. Following 2-9 days incubation period, the disease abruptly starts with fever, feeling cold, shivering, headache, muscle and joint aches. After a few days hemorrhage develops at various parts of the body. Since an effective vaccine and a specific antiviral therapy have not been found yet, the high mortality rate which may reach to 10-60%, and a wide geography affecting approximately 40 countries including Turkey, CCHF attracts the attention of both scientific and mediatic world, in recent years. In this article, the structure, vectors and reservoirs of CCHF virus, together with the epidemiology, clinical features, laboratory diagnosis and strategies of treatment and prevention, have been reviewed.

Hydrology, water resources and the epidemiology of water-related diseases

NASA Astrophysics Data System (ADS)

Bertuzzo, Enrico; Mari, Lorenzo

2017-10-01

Water-borne and water-based diseases are infections in which the causative agent (or one of its hosts) spends at least part of its lifecycle in water [1]. They still represent a major threat to human health, especially in the developing world. As an example, diarrhoea, commonly linked to water-borne diseases like cholera, is responsible for the death of about 525,000 children under five every year (out of nearly 1.7 billion cases globally), thus representing one of the leading causes of death among infants and children in low-income countries [2]. A wide range of micro- (protozoa, bacteria, viruses, algae) and macro-parasites (mostly flatworms and roundworms) is associated with water-borne and water-based diseases. Infection is generally caused by ingestion of, or exposure to, contaminated water, and is thus tightly linked to water excess, scarcity, availability or quality. More broadly, the term water-related diseases may also include vector-borne infections in which the ecology of the vector population is closely related to the presence of environmental water. This is the case, for instance, of mosquitoes acting as vectors of deadly diseases like malaria, dengue fever and yellow fever. Malaria alone exacted a toll of 429,000 deaths in 2015 (out of 212 million cases globally), according to the latest WHO estimates [3].

Geographic range of vector-borne infections and their vectors: the role of African wildlife.

PubMed

van Vuuren, M; Penzhorn, B L

2015-04-01

The role of African wildlife in the occurrence of vector-borne infections in domestic animals has gained renewed interest as emerging and re-emerging infections occur worldwide at an increasing rate. In Africa, biodiversity conservation and the expansion of livestock production have increased the risk of transmitting vector-borne infections between wildlife and livestock. The indigenous African pathogens with transboundary potential, such as Rift Valley fever virus, African horse sickness virus, bluetongue virus, lumpy skin disease virus, African swine fever virus, and blood-borne parasites have received the most attention. There is no evidence for persistent vector-borne viral infections in African wildlife. For some viral infections, wildlife may act as a reservoir through the inter-epidemic circulation of viruses with mild or subclinical manifestations. Wildlife may also act as introductory or transporting hosts when moved to new regions, e.g. for lumpy skin disease virus, Rift Valley fever virus and West Nile virus. Wildlife may also act as amplifying hosts when exposed to viruses in the early part of the warm season when vectors are active, with spillover to domestic animals later in the season, e.g. with bluetongue and African horse sickness. Some tick species found on domestic animals are more abundant on wildlife hosts; some depend on wildlife hosts to complete their life cycle. Since the endemic stability of a disease depends on a sufficiently large tick population to ensure that domestic animals become infected at an early age, the presence of wildlife hosts that augment tick numbers may be beneficial. Many wild ungulate species are reservoirs of Anaplasma spp., while the role of wildlife in the epidemiology of heartwater (Ehrlichia ruminantium infection) has not been elucidated. Wild ungulates are not usually reservoirs of piroplasms that affect livestock; however, there are two exceptions: zebra, which are reservoirs of Babesia caballi and Theileria equi, and buffalo, which are reservoirs of Theileria parva. The latter causes Corridor disease when transmitted from buffaloto cattle, butthis appearsto be a self-limiting condition, at least in southern Africa. Wild animals are important reservoirs of tsetse-transmitted Trypanosoma spp. infection. The distribution and abundance of some tsetse species, e.g. Glossina morsitans and G. pallidipes, are closely related to the occurrence of their preferred wildlife hosts.

Disease Risk in a Dynamic Environment: The Spread of Tick-Borne Pathogens in Minnesota, USA

PubMed Central

Robinson, Stacie J.; Neitzel, David F.; Moen, Ronald A.; Craft, Meggan E.; Hamilton, Karin E.; Johnson, Lucinda B.; Mulla, David J.; Munderloh, Ulrike G.; Redig, Patrick T.; Smith, Kirk E.; Turner, Clarence L.; Umber, Jamie K.; Pelican, Katharine M.

2015-01-01

As humans and climate change alter the landscape, novel disease risk scenarios emerge. Understanding the complexities of pathogen emergence and subsequent spread as shaped by landscape heterogeneity is crucial to understanding disease emergence, pinpointing high-risk areas, and mitigating emerging disease threats in a dynamic environment. Tick-borne diseases present an important public health concern and incidence of many of these diseases are increasing in the United States. The complex epidemiology of tick-borne diseases includes strong ties with environmental factors that influence host availability, vector abundance, and pathogen transmission. Here, we used 16 years of case data from the Minnesota Department of Health to report spatial and temporal trends in Lyme disease (LD), human anaplasmosis, and babesiosis. We then used a spatial regression framework to evaluate the impact of landscape and climate factors on the spread of LD. Finally, we use the fitted model, and landscape and climate datasets projected under varying climate change scenarios, to predict future changes in tick-borne pathogen risk. Both forested habitat and temperature were important drivers of LD spread in Minnesota. Dramatic changes in future temperature regimes and forest communities predict rising risk of tick-borne disease. PMID:25281302

Disease risk in a dynamic environment: the spread of tick-borne pathogens in Minnesota, USA.

PubMed

Robinson, Stacie J; Neitzel, David F; Moen, Ronald A; Craft, Meggan E; Hamilton, Karin E; Johnson, Lucinda B; Mulla, David J; Munderloh, Ulrike G; Redig, Patrick T; Smith, Kirk E; Turner, Clarence L; Umber, Jamie K; Pelican, Katharine M

2015-03-01

As humans and climate change alter the landscape, novel disease risk scenarios emerge. Understanding the complexities of pathogen emergence and subsequent spread as shaped by landscape heterogeneity is crucial to understanding disease emergence, pinpointing high-risk areas, and mitigating emerging disease threats in a dynamic environment. Tick-borne diseases present an important public health concern and incidence of many of these diseases are increasing in the United States. The complex epidemiology of tick-borne diseases includes strong ties with environmental factors that influence host availability, vector abundance, and pathogen transmission. Here, we used 16 years of case data from the Minnesota Department of Health to report spatial and temporal trends in Lyme disease (LD), human anaplasmosis, and babesiosis. We then used a spatial regression framework to evaluate the impact of landscape and climate factors on the spread of LD. Finally, we use the fitted model, and landscape and climate datasets projected under varying climate change scenarios, to predict future changes in tick-borne pathogen risk. Both forested habitat and temperature were important drivers of LD spread in Minnesota. Dramatic changes in future temperature regimes and forest communities predict rising risk of tick-borne disease.

Bacterial and protozoal agents of canine vector-borne diseases in the blood of domestic and stray dogs from southern Portugal.

PubMed

Maia, Carla; Almeida, Bruno; Coimbra, Mónica; Fernandes, Maria Catarina; Cristóvão, José Manuel; Ramos, Cláudia; Martins, Ângela; Martinho, Filipe; Silva, Pedro; Neves, Nuno; Nunes, Mónica; Vieira, Maria Luísa; Cardoso, Luís; Campino, Lenea

2015-03-23

The so-called canine vector-borne diseases (CVBD) are caused by a wide range of pathogens transmitted by arthropods. In addition to their veterinary importance, many of these canine vector-borne pathogens can also affect the human population due to their zoonotic potential, a situation that requires a One Health approach. As the prevalence of vector-borne pathogens in cats from southern Portugal has been recently evaluated, the aim of the present study was to assess if the same agents were present in dogs living in the same area, and to assess positivity-associated risk factors. One thousand and ten dogs (521 domestic and 489 stray) from veterinary medical centres and animal shelters in southern Portugal were enrolled. Anaplasma spp./Ehrlichia spp., Bartonella spp., Borrelia burgdorferi sensu lato, Babesia spp., Hepatozoon spp. and Leishmania infantum infections were evaluated by polymerase chain reaction (PCR) assays in blood samples. Sixty-eight (6.7%) dogs were PCR-positive to at least one of the tested CVBD agent species, genera or complex, including one dog found positive to two different genera. Nineteen (1.9%) dogs were positive to Anaplasma spp./Ehrlichia spp., eight (0.8%) to B. burgdorferi s.l., 31 (3.1%) to Hepatozoon spp. and 11 (1.1%) to L. infantum. Anaplasma platys, Ehrlichia canis, B. burgdorferis.l. and Hepatozoon canis were identified by DNA sequencing, including one animal confirmed with both A. platys and H. canis. Furthermore, Wolbachia spp. was amplified in blood from four dogs. None of the tested dogs was positive by PCR for Bartonella spp. or Babesia spp. The molecular identification of CVBD agents in southern Portugal, some of them with zoonotic concern, reinforces the importance to alert the veterinary community, owners and public health authorities to prevent the risk of transmission of vector-borne pathogens among dogs and to other vertebrate hosts including humans. The prevalence of the selected pathogens was lower than that previously found in cats from the same region, probably because veterinarians and owners are more aware of them in the canine population and control measures are used more often.

Criteria for the prioritization of public health interventions for climate-sensitive vector-borne diseases in Quebec

PubMed Central

Gosselin, Pierre; Michel, Pascal; Ravel, André; Waaub, Jean-Philippe; Campagna, Céline; Samoura, Karim

2017-01-01

Prioritizing resources for optimal responses to an ever growing list of existing and emerging infectious diseases represents an important challenge to public health. In the context of climate change, there is increasing anticipated variability in the occurrence of infectious diseases, notably climate-sensitive vector-borne diseases. An essential step in prioritizing efforts is to identify what considerations and concerns to take into account to guide decisions and thus set disease priorities. This study was designed to perform a comprehensive review of criteria for vector-borne disease prioritization, assess their applicability in a context of climate change with a diverse cross-section of stakeholders in order to produce a baseline list of considerations to use in this decision-making context. Differences in stakeholder choices were examined with regards to prioritization of these criteria for research, surveillance and disease prevention and control objectives. A preliminary list of criteria was identified following a review of the literature. Discussions with stakeholders were held to consolidate and validate this list of criteria and examine their effects on disease prioritization. After this validation phase, a total of 21 criteria were retained. A pilot vector-borne disease prioritization exercise was conducted using PROMETHEE to examine the effects of the retained criteria on prioritization in different intervention domains. Overall, concerns expressed by stakeholders for prioritization were well aligned with categories of criteria identified in previous prioritization studies. Weighting by category was consistent between stakeholders overall, though some significant differences were found between public health and non-public health stakeholders. From this exercise, a general model for climate-sensitive vector-borne disease prioritization has been developed that can be used as a starting point for further public health prioritization exercises relating to research, surveillance, and prevention and control interventions in a context of climate change. Multi-stakeholder engagement in prioritization can help broaden the range of criteria taken into account, offer opportunities for early identification of potential challenges and may facilitate acceptability of any resulting decisions. PMID:29281726

Epidemic dynamics of a vector-borne disease on a villages-and-city star network with commuters.

PubMed

Mpolya, Emmanuel A; Yashima, Kenta; Ohtsuki, Hisashi; Sasaki, Akira

2014-02-21

We develop a star-network of connections between a central city and peripheral villages and analyze the epidemic dynamics of a vector-borne disease as influenced by daily commuters. We obtain an analytical solution for the global basic reproductive number R0 and investigate its dependence on key parameters for disease control. We find that in a star-network topology the central hub is not always the best place to focus disease intervention strategies. Disease control decisions are sensitive to the number of commuters from villages to the city as well as the relative densities of mosquitoes between villages and city. With more commuters it becomes important to focus on the surrounding villages. Commuting to the city paradoxically reduces the disease burden even when the bulk of infections are in the city because of the resulting diluting effects of transmissions with more commuters. This effect decreases with heterogeneity in host and vector population sizes in the villages due to the formation of peripheral epicenters of infection. We suggest that to ensure effective control of vector-borne diseases in star networks of villages and cities it is also important to focus on the commuters and where they come from. © 2013 Published by Elsevier Ltd.

An application of remotely derived climatological fields for risk assessment of vector-borne diseases : a spatial study of filariasis prevalence in the Nile Delta, Egypt.

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

Crombie, M. K.; Gillies, R. R.; Arvidson, R. E.

1999-12-01

This paper applies a relatively straightforward remote sensing method that is commonly used to derive climatological variables. Measurements of surface reflectance and surface radiant temperature derived from Landsat Thematic Mapper data were used to create maps of fractional vegetation and surface soil moisture availability for the southern Nile delta in Egypt. These climatological variables were subsequently used to investigate the spatial distribution of the vector borne disease Bancroftian filariasis in the Nile delta where it is focally endemic and a growing problem. Averaged surface soil moisture values, computed for a 5-km border area around affected villages, were compared to filariasismore » prevalence rates. Prevalence rates were found to be negligible below a critical soil moisture value of 0.2, presumably because of a lack of appropriate breeding sites for the Culex Pipiens mosquito species. With appropriate modifications to account for local conditions and vector species, this approach should be useful as a means to map, predict, and control insect vector-borne diseases that critically depend on wet areas for propagation. This type of analysis may help governments and health agencies that are involved in filariasis control to better focus limited resources to identifiable high-risk areas.« less

Climate teleconnections, weather extremes, and vector-borne disease outbreaks

USDA-ARS?s Scientific Manuscript database

Fluctuations in climate lead to extremes in temperature, rainfall, flooding, and droughts. These climate extremes create ideal ecological conditions that promote mosquito-borne disease transmission that impact global human and animal health. One well known driver of such global scale climate fluctua...

Perceived threat of violence and exposure to physical violence against foreign-born women: a Swedish population-based study.

PubMed

Fernbrant, Cecilia; Essén, Birgitta; Ostergren, Per-Olof; Cantor-Graae, Elizabeth

2011-01-01

Violence against women is an increasing global phenomenon. Little is known about violence against foreign-born women, despite a possible increased concentration of risk factors in this group. This study investigated prevalence of perceived threat of violence and exposure to physical violence and its relation to country of birth among women (18-64 years) residing in southern Sweden, using data obtained from the 2004 Public Health Survey in Scania, Sweden. Foreign-born women reported significantly higher rates of both perceived threat of violence and exposure to physical violence compared with Swedish-born women. Foreign-born women exposed to violence originated primarily from middle/low-income countries (versus high-income countries). The risk of perceived threat of violence remained significantly increased among foreign-born even after further adjustment for potential confounders, such as marital status and disposable income. After similar adjustment, increased exposure to physical violence was no longer significantly related to foreign-born status, but instead was largely attributable to marital status and low levels of disposable income. Foreign-born women, however, had a greater risk of physical violence in the home than Swedish-born women, and violence in the home was the most frequently reported setting for violence exposure among foreign-born women. Migration may confer an increased risk of interpersonal violence against women. Although the underlying causes of this increased risk are unknown, a complex set of factors may be involved, including socioeconomic disadvantage. Copyright © 2011 Jacobs Institute of Women's Health. Published by Elsevier Inc. All rights reserved.

Community diversity of mosquitoes and their microbes across different habitats endemic for West Nile Virus and other arthropod-borne diseases

NASA Astrophysics Data System (ADS)

Liu, R.; Bennett, S. N.; Thongsripong, P.; Chandler, J. S.

2013-12-01

Mosquitoes have long been vectors for disease, and humans, birds, and other vertebrates have served their role as hosts in the transmission cycle of arthropod-borne viruses. In California, there are several mosquito species that act as vectors, transmitting such disease agents as Western equine and St. Louis encephalitis viruses, filarial nematodes, Plasmodium (which causes malaria), and West Nile virus (WNV). Last year (2012-2013), California had over 450 reported cases of West Nile Virus in humans (http://westnile.ca.gov/). To begin to understand mosquitoes and their role in the bay area as vectors of diseases, including West Nile Virus, we trapped mosquitoes from various sites and examined their microbiomes, including bacteria, fungi, viruses, and eukaryotes. Study sites were in Marin, San Mateo, and San Francisco counties, in areas that represented, respectively, rural, suburban, and urban habitats. The mosquitoes were identified through morphological characteristics, and verified molecularly by sequencing of the cytochrome oxidase I (COI) gene extracted from a leg. Most mosquitoes were collected from San Mateo and Mill Valley and were identified as Culiseta incidens. Data from traditional culture-based and next-generation 454 sequencing methods applied to mosquito whole bodies, representing their microbiomes, will be discussed, to determine how mosquito and microbial diversity varies across sites sampled in the San Francisco Bay area.

Vector-Borne Diseases in Stray Dogs in Peninsular Malaysia and Molecular Detection of Anaplasma and Ehrlichia spp. from Rhipicephalus sanguineus (Acari: Ixodidae) Ticks.

PubMed

Koh, Fui Xian; Panchadcharam, Chandrawathani; Tay, Sun Tee

2016-01-01

Little data are available on the prevalence and transmission of vector-borne diseases in stray dogs in Peninsular Malaysia. This study was designed to determine the occurrence of vector-borne pathogens in Malaysian stray dogs using serological and molecular approaches. In total, 48 dog blood samples were subjected to serological analysis using SNAP 4Dx kit (IDEXX Laboratories, Westbrook, ME). The presence of Ehrlichia and Anaplasma DNA in the dog blood samples and Rhipicephalus sanguineus (Latreille) ticks was detected using nested polymerase chain reaction assays. Positive serological findings against Ehrlichia canis and Anaplasma phagocytophilum were obtained in 17 (39.5%) and four (9.3%) of 43 dog samples, respectively. None of the dog blood samples were positive for Borrelia burgdorferi and Dirofilaria immitis. DNA of E. canis and A. phagocytophilum was detected in 12 (25.5%) and two (4.3%) of 47 dog blood samples, and 17 (51.5%) and one (3.0%) of 33 R. sanguineus ticks, respectively. Additionally, DNA of Ehrlichia spp. closely related to Ehrlichia chaffeensis was detected in two (6.1%) R. sanguineus ticks. This study highlights the prevalence of anaplasmosis and ehrlichiosis in dogs in Malaysia. Due to the zoonotic potential of Ehrlichia and Anaplasma spp., appropriate measures should be instituted for prevention and control of vector-borne diseases in dogs. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Impact of climate change upon vector born diseases in Europe and Africa using ENSEMBLES Regional Climate Models

NASA Astrophysics Data System (ADS)

Caminade, Cyril; Morse, Andy

2010-05-01

Climate variability is an important component in determining the incidence of a number of diseases with significant human/animal health and socioeconomic impacts. The most important diseases affecting health are vector-borne, such as malaria, Rift Valley Fever and including those that are tick borne, with over 3 billion of the world population at risk. Malaria alone is responsible for at least one million deaths annually, with 80% of malaria deaths occurring in sub-Saharan Africa. The climate has a large impact upon the incidence of vector-borne diseases; directly via the development rates and survival of both the pathogen and the vector, and indirectly through changes in the environmental conditions. A large ensemble of regional climate model simulations has been produced within the ENSEMBLES project framework for both the European and African continent. This work will present recent progress in human and animal disease modelling, based on high resolution climate observations and regional climate simulations. Preliminary results will be given as an illustration, including the impact of climate change upon bluetongue (disease affecting the cattle) over Europe and upon malaria and Rift Valley Fever over Africa. Malaria scenarios based on RCM ensemble simulations have been produced for West Africa. These simulations have been carried out using the Liverpool Malaria Model. Future projections highlight that the malaria incidence decreases at the northern edge of the Sahel and that the epidemic belt is shifted southward in autumn. This could lead to significant public health problems in the future as the demography is expected to dramatically rise over Africa for the 21st century.

Oocysts of Hepatozoon canis in Rhipicephalus (Boophilus) microplus collected from a naturally infected dog.

PubMed

de Miranda, Renata Lima; de Castro, Jacqueline Ribeiro; Olegário, Maria Marlene Martins; Beletti, Marcelo Emílio; Mundim, Antonio Vicente; O'Dwyer, Lucia Helena; Eyal, Osnat; Talmi-Frank, Dalit; Cury, Márcia Cristina; Baneth, Gad

2011-05-11

Canine hepatozoonosis is a tick-borne disease caused by protozoans of the genus Hepatozoon. Several tick species have been implicated as potential vectors. Therefore, extensive studies are needed to determine the 'natural' endemic cycle of this parasite. This paper presents the first report of the presence of Hepatozoon canis oocysts in Rhipicephalus (Boophilus) microplus collected from an infected dog. Copyright © 2011 Elsevier B.V. All rights reserved.

Yellow fever in China is still an imported disease.

PubMed

Chen, Jun; Lu, Hongzhou

2016-05-23

Yellow fever is a vector-borne disease endemic to tropical regions of Africa and South America. A recent outbreak in Angola caused hundreds of deaths. Six cases of yellow fever imported from Angola were reported recently in China. This raised the question of whether it will spread in China and how it can be prevented. This article discusses the possibility of yellow fever transmission in China and the strategies to counter it.

[Going into the 21st century: should one dream or act?].

PubMed

Coosemans, M

1991-01-01

A historical review of vector control is made. Despite the available tools, vector borne diseases are still a priority in Public Health. Magic tools, like DDT, were often misused. Adapted strategies and structures for vector control are now required. Progress will mainly result from research and evaluation done in the framework of vector control programmes. Discovery of new tools will find in these operational programmes a point of fall for their application.

The poultry red mite (Dermanyssus gallinae): a potential vector of pathogenic agents.

PubMed

Valiente Moro, Claire; De Luna, Carlos J; Tod, Alexander; Guy, Jonathan H; Sparagano, Olivier A E; Zenner, Lionel

2009-06-01

The poultry red mite, D. gallinae has been involved in the transmission of many pathogenic agents, responsible for serious diseases both in animals and humans. Nowadays, few effective methods are available to control the ectoparasite in poultry farms. Consequently, this is an emerging problem which must be taken into account to maintain good health in commercial egg production. This paper addresses the vector capacity of the ectoparasite with special emphasis on salmonellae, pathogenic agents responsible for many of the most important outbreaks of food-borne diseases worlwide. It has been experimentally shown that D. gallinae could act as a biological vector of S. enteritidis and natural carriage of these bacteria by the mite on poultry premises has also been reported. It was also found that D. gallinae carried other pathogens such as E. coli, Shigella sp., and Staphylococcus, thus increasing the list of pathogenic agents potentially transmitted by the mite.

A spatially explicit metapopulation model and cattle trade analysis suggests key determinants for the recurrent circulation of rift valley Fever virus in a pilot area of madagascar highlands.

PubMed

Nicolas, Gaëlle; Chevalier, Véronique; Tantely, Luciano Michaël; Fontenille, Didier; Durand, Benoît

2014-12-01

Rift Valley fever (RVF) is a vector-borne zoonotic disease that causes high morbidity and mortality in ruminants. In 2008-2009, a RVF outbreak affected the whole Madagascar island, including the Anjozorobe district located in Madagascar highlands. An entomological survey showed the absence of Aedes among the potential RVF virus (RVFV) vector species identified in this area, and an overall low abundance of mosquitoes due to unfavorable climatic conditions during winter. No serological nor virological sign of infection was observed in wild terrestrial mammals of the area, suggesting an absence of wild RVF virus (RVFV) reservoir. However, a three years serological and virological follow-up in cattle showed a recurrent RVFV circulation. The objective of this study was to understand the key determinants of this unexpected recurrent transmission. To achieve this goal, a spatial deterministic discrete-time metapopulation model combined with cattle trade network was designed and parameterized to reproduce the local conditions using observational data collected in the area. Three scenarios that could explain the RVFV recurrent circulation in the area were analyzed: (i) RVFV overwintering thanks to a direct transmission between cattle when viraemic cows calve, vectors being absent during the winter, (ii) a low level vector-based circulation during winter thanks to a residual vector population, without direct transmission between cattle, (iii) combination of both above mentioned mechanisms. Multi-model inference methods resulted in a model incorporating both a low level RVFV winter vector-borne transmission and a direct transmission between animals when viraemic cows calve. Predictions satisfactorily reproduced field observations, 84% of cattle infections being attributed to vector-borne transmission, and 16% to direct transmission. These results appeared robust according to the sensitivity analysis. Interweaving between agricultural works in rice fields, seasonality of vector proliferation, and cattle exchange practices could be a key element for understanding RVFV circulation in this area of Madagascar highlands.

Vector-borne transmission of Trypanosoma cruzi among captive Neotropical primates in a Brazilian zoo.

PubMed

Minuzzi-Souza, Thaís Tâmara Castro; Nitz, Nadjar; Knox, Monique Britto; Reis, Filipe; Hagström, Luciana; Cuba, César A Cuba; Hecht, Mariana Machado; Gurgel-Gonçalves, Rodrigo

2016-01-26

Neotropical primates are important sylvatic hosts of Trypanosoma cruzi, the etiological agent of Chagas disease. Infection is often subclinical, but severe disease has been described in both free-ranging and captive primates. Panstrongylus megistus, a major T. cruzi vector, was found infesting a small-primate unit at Brasília zoo (ZooB), Brazil. ZooB lies close to a gallery-forest patch where T. cruzi circulates naturally. Here, we combine parasitological and molecular methods to investigate a focus of T. cruzi infection involving triatomine bugs and Neotropical primates at a zoo located in the Brazilian Savannah. We assessed T. cruzi infection in vectors using optical microscopy (n = 34) and nested PCR (n = 50). We used quantitative PCR (qPCR) to examine blood samples from 26 primates and necropsy samples from two primates that died during the study. We determined parasite lineages in five vectors and two primates by comparing glucose-6-phosphate isomerase (G6pi) gene sequences. Trypanosoma cruzi was found in 44 vectors and 17 primates (six genera and eight species); one Mico chrysoleucus and one Saguinus niger had high parasitaemias. Trypanosoma cruzi DNA was detected in three primates born to qPCR-negative mothers at ZooB and in the two dead specimens. One Callithrix geoffroyi became qPCR-positive over a two-year follow-up. All G6pi sequences matched T. cruzi lineage TcI. Our findings strongly suggest vector-borne T. cruzi transmission within a small-primate unit at ZooB - with vectors, and perhaps also parasites, presumably coming from nearby gallery forest. Periodic checks for vectors and parasites would help eliminate T. cruzi transmission foci in captive-animal facilities. This should be of special importance for captive-breeding programs involving endangered mammals, and would reduce the risk of accidental T. cruzi transmission to keepers and veterinarians.

[Analysis of morbidity and mortality characteristics of the notifiable diseases reported in 2013 in China].

PubMed

Wang, Liping; Zeng, Lingjia; Ren, Xiang; Geng, Mengjie; Li, Zhongjie; Yu, Hongjie

2015-03-01

To learn the characteristics of morbidity and mortality of notifiable diseases reported in China in 2013. Descriptive analysis method was used to analyze the morbidity and mortality of notifiable diseases in China in 2013, with Microsoft Excel 2010 and ArcGIS 10.0 used to develop statistical charts. In 2013, the morbidity of the nationwide notifiable diseases was 473.87/100 000, a decrease of 3% below the average of the recent 3 years, while the mortality was 1.23/100 000, an increase of 2% over the average of the recent 3 years. The rate of laboratory diagnosis of the reported cases was 38.4%. Top 5 diseases of the reported incidence were hand foot and mouth disease, other infectious diarrhea, hepatitis B, tuberculosis and syphilis. The death cases reported were mainly AIDS, tuberculosis and rabies. As classified by the transmission route analysis, intestinal infectious diseases accounted for 49% of the total incidence reported for the year, followed by the blood and sexually transmitted infectious diseases, respiratory infectious diseases, animal and vector borne infectious diseases. According to the pathogenic analysis, virus infectious diseases accounted for 68% of the total cases, higher than bacterial infectious diseases and animal-borne/vector-borne infectious diseases. In Shanghai, Zhejiang and Jiangsu, human infection with avian influenza A (H7N9) virus was emerging, as epidemic situation of measles, dengue fever and brucellosis were on the rise significantly nationwide, while the morbidity of infectious diseases decreased, namely pulmonary tuberculosis, hepatitis B among others. Morbidity of the top 5 provinces for notifiable infectious diseases were Hainan, Guangxi, Guangdong, Xinjiang and Zhejiang, respectively. The proportion of laboratory confirmed cases among totals was still low in 2013. The morbidity of the infectious diseases was higher in western provinces and parts of south-eastern province, the mortality was higher in western provinces. The emerging human infection with avian influenza A (H7N9) virus, and the high epidemic of measles, dengue fever and brucellosis in some areas had caught the society concerns.

A method of determining where to target surveillance efforts in heterogeneous epidemiological systems

PubMed Central

van den Bosch, Frank; Gottwald, Timothy R.; Alonso Chavez, Vasthi

2017-01-01

The spread of pathogens into new environments poses a considerable threat to human, animal, and plant health, and by extension, human and animal wellbeing, ecosystem function, and agricultural productivity, worldwide. Early detection through effective surveillance is a key strategy to reduce the risk of their establishment. Whilst it is well established that statistical and economic considerations are of vital importance when planning surveillance efforts, it is also important to consider epidemiological characteristics of the pathogen in question—including heterogeneities within the epidemiological system itself. One of the most pronounced realisations of this heterogeneity is seen in the case of vector-borne pathogens, which spread between ‘hosts’ and ‘vectors’—with each group possessing distinct epidemiological characteristics. As a result, an important question when planning surveillance for emerging vector-borne pathogens is where to place sampling resources in order to detect the pathogen as early as possible. We answer this question by developing a statistical function which describes the probability distributions of the prevalences of infection at first detection in both hosts and vectors. We also show how this method can be adapted in order to maximise the probability of early detection of an emerging pathogen within imposed sample size and/or cost constraints, and demonstrate its application using two simple models of vector-borne citrus pathogens. Under the assumption of a linear cost function, we find that sampling costs are generally minimised when either hosts or vectors, but not both, are sampled. PMID:28846676

Notes from the Field: Outbreak of Zika Virus Disease - American Samoa, 2016.

PubMed

Healy, Jessica M; Burgess, M Catherine; Chen, Tai-Ho; Hancock, W Thane; Toews, Karrie-Ann E; Anesi, Magele Scott; Tulafono, Ray T; Mataia, Mary Aseta; Sili, Benjamin; Solaita, Jacqueline; Whelen, A Christian; Sciulli, Rebecca; Gose, Remedios B; Uluiviti, Vasiti; Hennessey, Morgan; Utu, Fara; Nua, Motusa Tuileama; Fischer, Marc

2016-10-21

During December 2015-January 2016, the American Samoa Department of Health (ASDoH) detected through surveillance an increase in the number of cases of acute febrile rash illness. Concurrently, a case of laboratory-confirmed Zika virus infection, a mosquito-borne flavivirus infection documented to cause microcephaly and other severe brain defects in some infants born to women infected during pregnancy (1,2) was reported in a traveler returning to New Zealand from American Samoa. In the absence of local laboratory capacity to test for Zika virus, ASDoH initiated arboviral disease control measures, including public education and vector source reduction campaigns. On February 1, CDC staff members were deployed to American Samoa to assist ASDoH with testing and surveillance efforts.

An Environmental Data Set for Vector-Borne Disease Modeling and Epidemiology

PubMed Central

Chabot-Couture, Guillaume; Nigmatulina, Karima; Eckhoff, Philip

2014-01-01

Understanding the environmental conditions of disease transmission is important in the study of vector-borne diseases. Low- and middle-income countries bear a significant portion of the disease burden; but data about weather conditions in those countries can be sparse and difficult to reconstruct. Here, we describe methods to assemble high-resolution gridded time series data sets of air temperature, relative humidity, land temperature, and rainfall for such areas; and we test these methods on the island of Madagascar. Air temperature and relative humidity were constructed using statistical interpolation of weather station measurements; the resulting median 95th percentile absolute errors were 2.75°C and 16.6%. Missing pixels from the MODIS11 remote sensing land temperature product were estimated using Fourier decomposition and time-series analysis; thus providing an alternative to the 8-day and 30-day aggregated products. The RFE 2.0 remote sensing rainfall estimator was characterized by comparing it with multiple interpolated rainfall products, and we observed significant differences in temporal and spatial heterogeneity relevant to vector-borne disease modeling. PMID:24755954

Tick-borne infections in human and animal population worldwide

PubMed Central

Brites-Neto, José; Duarte, Keila Maria Roncato; Martins, Thiago Fernandes

2015-01-01

The abundance and activity of ectoparasites and its hosts are affected by various abiotic factors, such as climate and other organisms (predators, pathogens and competitors) presenting thus multiples forms of association (obligate to facultative, permanent to intermittent and superficial to subcutaneous) developed during long co-evolving processes. Ticks are ectoparasites widespread globally and its eco epidemiology are closely related to the environmental conditions. They are obligatory hematophagous ectoparasites and responsible as vectors or reservoirs at the transmission of pathogenic fungi, protozoa, viruses, rickettsia and others bacteria during their feeding process on the hosts. Ticks constitute the second vector group that transmit the major number of pathogens to humans and play a role primary for animals in the process of diseases transmission. Many studies on bioecology of ticks, considering the information related to their population dynamics, to the host and the environment, comes possible the application and efficiency of tick control measures in the prevention programs of vector-borne diseases. In this review were considered some taxonomic, morphological, epidemiological and clinical fundamental aspects related to the tick-borne infections that affect human and animal populations. PMID:27047089

West Nile Virus Retinopathy and Associations with Long Term Neurological and Neurocognitive Sequelae.

PubMed

Hasbun, Rodrigo; Garcia, Melissa N; Kellaway, Judianne; Baker, Laura; Salazar, Lucrecia; Woods, Steven Paul; Murray, Kristy O

2016-01-01

West Nile virus (WNV) has emerged as an important vector-borne pathogen in North America, with more than 3 million estimated to have been infected. Retinopathy from WNV infection has been previously reported in acute cases, though those prior reports did not evaluate the risk of retinopathy based on clinical severity of neurologic disease. The purpose of this cross-sectional study was to perform comprehensive ophthalmological and neurological examinations on 111 patients with a history of West Nile virus infection and describe the ocular manifestations. Out of 111 patients, 27 (24%) had evidence for West Nile virus associated retinopathy (WNVR); this observation was higher (49%) in those patients who initially presented with encephalitis. Individuals with WNVR had more frequent involvement of the macula and peripheral involvement compared to those patients without WNVR (p<0.05). WNVR was also associated with a greater likelihood of abnormal reflexes on neurological exam, poorer learning, greater dependence in activities of daily living, and lower quality of life (p<0.05). WNVR was seen more frequently in elderly patients (age > 60 years), and was associated with higher rates of diabetes mellitus and a history of encephalitis (p<0.05). A multivariable logistic regression revealed that only a history of encephalitis was independently associated with WNVR [Adjusted Odds Ratio = 4.9 (1.8-13.2); p = 0.001]. Our study found that WNVR occurs in one fourth of patients with a history of WNV infection and is more frequently observed in those with apparent severe neurological sequelae (e.g., encephalitis). The clinical relevance of WNVR was supported by its associations with dependence in activities of daily living and lower quality of life. This unique evaluation of WNV patients included fundoscopic examinations and their associations with neurologic impairment. Our findings can be used during ophthalmological consultation for the evaluation, treatment and rehabilitation phases of care for WNV patients.

Analysis of Distribution of Vector-Borne Diseases Using Geographic Information Systems.

PubMed

Nihei, Naoko

2017-01-01

The distribution of vector-borne diseases is changing on a global scale owing to issues involving natural environments, socioeconomic conditions and border disputes among others. Geographic information systems (GIS) provide an important method of establishing a prompt and precise understanding of local data on disease outbreaks, from which disease eradication programs can be established. Having first defined GIS as a combination of GPS, RS and GIS, we showed the processes through which these technologies were being introduced into our research. GIS-derived geographical information attributes were interpreted in terms of point, area, line, spatial epidemiology, risk and development for generating the vector dynamic models associated with the spread of the disease. The need for interdisciplinary scientific and administrative collaboration in the use of GIS to control infectious diseases is highly warranted.

Molecular detection of the human pathogenic Rickettsia sp. strain Atlantic rainforest in Amblyomma dubitatum ticks from Argentina.

PubMed

Monje, Lucas D; Nava, Santiago; Eberhardt, Ayelen T; Correa, Ana I; Guglielmone, Alberto A; Beldomenico, Pablo M

2015-02-01

To date, three tick-borne pathogenic Rickettsia species have been reported in different regions of Argentina, namely, R. rickettsii, R. parkeri, and R. massiliae. However, there are no reports available for the presence of tick-borne pathogens from the northeastern region of Argentina. This study evaluated the infection with Rickettsia species of Amblyomma dubitatum ticks collected from vegetation and feeding from capybaras (Hydrochoerus hydrochaeris) in northeastern Argentina. From a total of 374 A. dubitatum ticks collected and evaluated by PCR for the presence of rickettsial DNA, 19 were positive for the presence of Rickettsia bellii DNA, two were positive for Rickettsia sp. strain COOPERI, and one was positive for the pathogenic Rickettsia sp. strain Atlantic rainforest. To our knowledge, this study is the first report of the presence of the human pathogen Rickettsia sp. strain Atlantic rainforest and Rickettsia sp. strain COOPERI in Argentina. Moreover, our findings posit A. dubitatum as a potential vector for this pathogenic strain of Rickettsia.

Guillain-Barre syndrome complicating chikungunya virus infection.

PubMed

Agarwal, Ayush; Vibha, Deepti; Srivastava, Achal Kumar; Shukla, Garima; Prasad, Kameshwar

2017-06-01

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus which presents with symptoms of fever, rash, arthralgia, and occasional neurologic disease. While outbreaks have been earlier reported from India and other parts of the world, the recent outbreak in India witnessed more than 1000 cases. Various systemic and rarely neurological complications have been reported with CHIKV. We report two cases of Guillain-Barré syndrome (GBS) with CHIKV. GBS is a rare neurological complication which may occur after subsidence of fever and constitutional symptoms by several neurotropic viruses. We describe two cases of severe GBS which presented with rapidly progressive flaccid quadriparesis progressing to difficulty in swallowing and breathing. Both required mechanical ventilation and improved partly with plasmapharesis. The cases emphasize on (1) description of the rare complication in a setting of outbreak with CHIKV, (2) acute axonal as well as demyelinating neuropathy may occur with CHIKV, (3) accurate identification of this entity during outbreaks with dengue, both of which are vector borne and may present with similar complications.

Climate change promotes the emergence of serious disease outbreaks for Filarioid nematodes

USDA-ARS?s Scientific Manuscript database

Scenarios for climate change involve direct linkages for increasing temperature, invasiveness and dissemination of vector-borne parasites. Coincidental with decades of warming, and anomalies of high temperature and humidity in Fennoscandia, the mosquito-borne filarioid nematode Setaria tundra is now...

Novel flaviviruses from mosquitoes: Mosquito-specific evolutionary lineages within the phylogenetic group of mosquito-borne flaviviruses

PubMed Central

Huhtamo, Eili; Cook, Shelley; Moureau, Gregory; Uzcátegui, Nathalie Y.; Sironen, Tarja; Kuivanen, Suvi; Putkuri, Niina; Kurkela, Satu; Harbach, Ralph E.; Firth, Andrew E.; Vapalahti, Olli; Gould, Ernest A.; de Lamballerie, Xavier

2014-01-01

Novel flaviviruses that are genetically related to pathogenic mosquito-borne flaviviruses (MBFV) have been isolated from mosquitoes in various geographical locations, including Finland. We isolated and characterized another novel virus of this group from Finnish mosquitoes collected in 2007, designated as Ilomantsi virus (ILOV). Unlike the MBFV that infect both vertebrates and mosquitoes, the MBFV-related viruses appear to be specific to mosquitoes similar to the insect-specific flaviviruses (ISFs). In this overview of MBFV-related viruses we conclude that they differ from the ISFs genetically and antigenically. Phylogenetic analyses separated the MBFV-related viruses isolated in Africa, the Middle East and South America from those isolated in Europe and Asia. Serological cross-reactions of MBFV-related viruses with other flaviviruses and their potential for vector-borne transmission require further characterization. The divergent MBFV-related viruses are probably significantly under sampled to date and provide new information on the variety, properties and evolution of vector-borne flaviviruses. PMID:25108382

Superinfection exclusion of the ruminant pathogen anaplasma marginale in the tick vector is dependent on time between exposures to the strains

USDA-ARS?s Scientific Manuscript database

The remarkable genetic diversity of vector-borne pathogens allows for the establishment of superinfection in the mammalian host. To have a long-term impact on population strain structure, the introduced strains must also be transmitted by a vector population that has been exposed to the existing pri...

Eco-bio-social determinants for house infestation by non-domiciliated Triatoma dimidiata in the Yucatan Peninsula, Mexico.

PubMed

Dumonteil, Eric; Nouvellet, Pierre; Rosecrans, Kathryn; Ramirez-Sierra, Maria Jesus; Gamboa-León, Rubi; Cruz-Chan, Vladimir; Rosado-Vallado, Miguel; Gourbière, Sébastien

2013-01-01

Chagas disease is a vector-borne disease of major importance in the Americas. Disease prevention is mostly limited to vector control. Integrated interventions targeting ecological, biological and social determinants of vector-borne diseases are increasingly used for improved control. We investigated key factors associated with transient house infestation by T. dimidiata in rural villages in Yucatan, Mexico, using a mixed modeling approach based on initial null-hypothesis testing followed by multimodel inference and averaging on data from 308 houses from three villages. We found that the presence of dogs, chickens and potential refuges, such as rock piles, in the peridomicile as well as the proximity of houses to vegetation at the periphery of the village and to public light sources are major risk factors for infestation. These factors explain most of the intra-village variations in infestation. These results underline a process of infestation distinct from that of domiciliated triatomines and may be used for risk stratification of houses for both vector surveillance and control. Combined integrated vector interventions, informed by an Ecohealth perspective, should aim at targeting several of these factors to effectively reduce infestation and provide sustainable vector control.

Rodent-borne diseases and their public health importance in Iran

PubMed Central

Mahmoudi, Ahmad; Siahsarvie, Roohollah; Kryštufek, Boris; Mostafavi, Ehsan

2018-01-01

Background Rodents are reservoirs and hosts for several zoonotic diseases such as plague, leptospirosis, and leishmaniasis. Rapid development of industry and agriculture, as well as climate change throughout the globe, has led to change or increase in occurrence of rodent-borne diseases. Considering the distribution of rodents throughout Iran, the aim of this review is to assess the risk of rodent-borne diseases in Iran. Methodology/Principal finding We searched Google Scholar, PubMed, Science Direct, Scientific Information Database (SID), and Magiran databases up to September 2016 to obtain articles reporting occurrence of rodent-borne diseases in Iran and extract information from them. Out of 70 known rodent-borne diseases, 34 were reported in Iran: 17 (50%) parasitic diseases, 13 (38%) bacterial diseases, and 4 (12%) viral diseases. Twenty-one out of 34 diseases were reported from both humans and rodents. Among the diseases reported in the rodents of Iran, plague, leishmaniasis, and hymenolepiasis were the most frequent. The most infected rodents were Rattus norvegicus (16 diseases), Mus musculus (14 diseases), Rattus rattus (13 diseases), Meriones persicus (7 diseases), Apodemus spp. (5 diseases), Tatera indica (4 diseases), Meriones libycus (3 diseases), Rhombomys opimus (3 diseases), Cricetulus migratorius (3 diseases), and Nesokia indica (2 diseases). Conclusions/Significance The results of this review indicate the importance of rodent-borne diseases in Iran. Considering notable diversity of rodents and their extensive distribution throughout the country, it is crucial to pay more attention to their role in spreading infectious diseases for better control of the diseases. PMID:29672510

Canine Leishmaniasis: An Overview of the Current Status and Strategies for Control

PubMed Central

Michalick, Marilene Suzan Marques; da Silva, Manoel Eduardo; dos Santos, Cristiano Cheim Peixoto; Frézard, Frédéric Jean Georges; da Silva, Sydnei Magno

2018-01-01

Canine leishmaniasis (CanL) is a vector-borne disease caused by Leishmania infantum and is transmitted by female phlebotomine sand flies primarily between animals and secondarily to humans. The course of infection may be different from one individual dog to another, ranging from spontaneous cure to acute evolution that leads to death, if proper management and therapy are not adopted. A parasitological cure is rarely achieved and clinical recurrences in CanL are frequent. Vaccination associated with the use of topical insecticides is undoubtedly the most effective form of prevention and control of the disease. In order to integrate the most important scientific knowledge of the literature in one objective publication, this review proposes a short overview of the main points of CanL. PMID:29789784

Tularaemia: a challenging zoonosis.

PubMed

Carvalho, C L; Lopes de Carvalho, I; Zé-Zé, L; Núncio, M S; Duarte, E L

2014-03-01

In recent years, several emerging zoonotic vector-borne infections with potential impact on human health have been identified in Europe, including tularaemia, caused by Francisella tularensis. This remarkable pathogen, one of the most virulent microorganisms currently known, has been detected in increasingly new settings and in a wide range of wild species, including lagomorphs, rodents, carnivores, fish and invertebrate arthropods. Also, a renewed concern has arisen with regard to F. tularensis: its potential use by bioterrorists. Based on the information published concerning the latest outbreaks, the aim of this paper is to review the main features of the agent, its biology, immunology and epidemiology. Moreover, special focus will be given to zoonotic aspects of the disease, as tularaemia outbreaks in human populations have been frequently associated with disease in animals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Priorities and needs for research on urban interventions targeting vector-borne diseases: rapid review of scoping and systematic reviews.

PubMed

Bermudez-Tamayo, Clara; Mukamana, Olive; Carabali, Mabel; Osorio, Lyda; Fournet, Florence; Dabiré, Kounbobr Roch; Turchi Marteli, Celina; Contreras, Adolfo; Ridde, Valéry

2016-12-01

This paper highlights the critical importance of evidence on vector-borne diseases (VBD) prevention and control interventions in urban settings when assessing current and future needs, with a view to setting policy priorities that promote inclusive and equitable urban health services. Research should produce knowledge about policies and interventions that are intended to control and prevent VBDs at the population level and to reduce inequities. Such interventions include policy, program, and resource distribution approaches that address the social determinants of health and exert influence at organizational and system levels.

Molecular Detection of Tick-Borne Pathogens in Humans with Tick Bites and Erythema Migrans, in the Netherlands

PubMed Central

Jahfari, Setareh; Hofhuis, Agnetha; Fonville, Manoj; van der Giessen, Joke; van Pelt, Wilfrid; Sprong, Hein

2016-01-01

Background Tick-borne diseases are the most prevalent vector-borne diseases in Europe. Knowledge on the incidence and clinical presentation of other tick-borne diseases than Lyme borreliosis and tick-borne encephalitis is minimal, despite the high human exposure to these pathogens through tick bites. Using molecular detection techniques, the frequency of tick-borne infections after exposure through tick bites was estimated. Methods Ticks, blood samples and questionnaires on health status were collected from patients that visited their general practitioner with a tick bite or erythema migrans in 2007 and 2008. The presence of several tick-borne pathogens in 314 ticks and 626 blood samples of this cohort were analyzed using PCR-based methods. Using multivariate logistic regression, associations were explored between pathogens detected in blood and self-reported symptoms at enrolment and during a three-month follow-up period. Results Half of the ticks removed from humans tested positive for Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Candidatus Neoehrlichia mikurensis, Rickettsia helvetica, Rickettsia monacensis, Borrelia miyamotoi and several Babesia species. Among 92 Borrelia burgdorferi s. l. positive ticks, 33% carried another pathogen from a different genus. In blood of sixteen out of 626 persons with tick bites or erythema migrans, DNA was detected from Candidatus Neoehrlichia mikurensis (n = 7), Anaplasma phagocytophilum (n = 5), Babesia divergens (n = 3), Borrelia miyamotoi (n = 1) and Borrelia burgdorferi s. l. (n = 1). None of these sixteen individuals reported any overt symptoms that would indicate a corresponding illness during the three-month follow-up period. No associations were found between the presence of pathogen DNA in blood and; self-reported symptoms, with pathogen DNA in the corresponding ticks (n = 8), reported tick attachment duration, tick engorgement, or antibiotic treatment at enrolment. Conclusions Based on molecular detection techniques, the probability of infection with a tick-borne pathogen other than Lyme spirochetes after a tick bite is roughly 2.4%, in the Netherlands. Similarly, among patients with erythema migrans, the probability of a co-infection with another tick-borne pathogen is approximately 2.7%. How often these infections cause disease symptoms or to what extend co-infections affect the course of Lyme borreliosis needs further investigations. PMID:27706159

The Fleas (Siphonaptera) in Iran: Diversity, Host Range, and Medical Importance.

PubMed

Maleki-Ravasan, Naseh; Solhjouy-Fard, Samaneh; Beaucournu, Jean-Claude; Laudisoit, Anne; Mostafavi, Ehsan

2017-01-01

Flea-borne diseases have a wide distribution in the world. Studies on the identity, abundance, distribution and seasonality of the potential vectors of pathogenic agents (e.g. Yersinia pestis, Francisella tularensis, and Rickettsia felis) are necessary tools for controlling and preventing such diseases outbreaks. The improvements of diagnostic tools are partly responsible for an easier detection of otherwise unnoticed agents in the ectoparasitic fauna and as such a good taxonomical knowledge of the potential vectors is crucial. The aims of this study were to make an exhaustive inventory of the literature on the fleas (Siphonaptera) and range of associated hosts in Iran, present their known distribution, and discuss their medical importance. The data were obtained by an extensive literature review related to medically significant fleas in Iran published before 31st August 2016. The flea-host specificity was then determined using a family and subfamily-oriented criteria to further realize and quantify the shared and exclusive vertebrate hosts of fleas among Iran fleas. The locations sampled and reported in the literature were primarily from human habitation, livestock farms, poultry, and rodents' burrows of the 31 provinces of the country. The flea fauna were dominated by seven families, namely the Ceratophyllidae, Leptopsyllidae, Pulicidae, Ctenophthalmidae, Coptopsyllidae, Ischnopsyllidae and Vermipsyllidae. The hosts associated with Iran fleas ranged from the small and large mammals to the birds. Pulicidae were associated with 73% (56/77) of identified host species. Flea-host association analysis indicates that rodents are the common hosts of 5 flea families but some sampling bias results in the reduced number of bird host sampled. Analyses of flea-host relationships at the subfamily level showed that most vertebrates hosted fleas belgonging to 3 subfamilies namely Xenopsyllinae (n = 43), Ctenophthalminae (n = 20) and Amphipsyllinae (n = 17). Meriones persicus was infested by 11 flea subfamilies in the arid, rocky, mountainous regions and Xenopsyllinae were hosted by at least 43 mammal species. These findings place the Persian jird (M. persicus) and the Xenopsyllinae as the major vertebrate and vector hosts of flea-borne diseases in Iran including Yersinia pestis, the etiological agent of plague. We found records of at least seven vector-borne pathogenic agents that can potentially be transmitted by the 117 flea species (or subspecies) of Iran. Herein, we performed a thorough inventary of the flea species and their associated hosts, their medical importance and geographic distribution throughout Iran. This exercise allowed assessing the diversity of flea species with the potential flea-borne agents transmission risk in the country by arranging published data on flea-host associations. This information is a first step for issuing public health policies and rodent-flea control campaigns in Iran as well as those interested in the ecology/epidemiology of flea-borne disease.

Using Earth Observation to Forecast Human and Animal Vector-Borne Disease Outbreaks

USDA-ARS?s Scientific Manuscript database

Earth observing technologies, including data from with earth-orbiting satellites, coupled with new investigations and a better understanding of the impact of environmental factors on transmission dynamics of mosquito-borne diseases permitted us to forecast Rift Valley fever (RVF) outbreaks in animal...

Impact of earthquake-induced tsunamis on public health

NASA Astrophysics Data System (ADS)

Mavroulis, Spyridon; Mavrouli, Maria; Lekkas, Efthymios; Tsakris, Athanassios

2017-04-01

Tsunamis are caused by rapid sea floor displacement during earthquakes, landslides and large explosive eruptions in marine environment setting. Massive amounts of sea water in the form of devastating surface waves travelling hundreds of kilometers per hour have the potential to cause extensive damage to coastal infrastructures, considerable loss of life and injury and emergence of infectious diseases (ID). This study involved an extensive and systematic literature review of 50 research publications related to public health impact of the three most devastating tsunamis of the last 12 years induced by great earthquakes, namely the 2004 Sumatra-Andaman earthquake (moment magnitude Mw 9.2), the 2009 Samoa earthquake (Mw 8.1) and the 2011 Tōhoku (Japan) earthquake (Mw 9.0) in the Indian, Western Pacific and South Pacific Oceans respectively. The inclusion criteria were literature type comprising journal articles and official reports, natural disaster type including tsunamis induced only by earthquakes, population type including humans, and outcome measure characterized by disease incidence increase. The potential post-tsunami ID are classified into 11 groups including respiratory, pulmonary, wound-related, water-borne, skin, vector-borne, eye, fecal-oral, food-borne, fungal and mite-borne ID. Respiratory infections were detected after all the above mentioned tsunamis. Wound-related, skin and water-borne ID were observed after the 2004 and 2011 tsunamis, while vector-borne, fecal-oral and eye ID were observed only after the 2004 tsunami and pulmonary, food-borne and mite-borne ID were diagnosed only after the 2011 tsunami. Based on available age and genre data, it is concluded that the most vulnerable population groups are males, children (age ≤ 15 years) and adults (age ≥ 65 years). Tetanus and pneumonia are the deadliest post-tsunami ID. The detected risk factors include (1) lowest socioeconomic conditions, poorly constructed buildings and lack of prevention measures, (2) lack of awareness and prior warning resulting in little time for preparedness or evacuation, (3) severely injured tsunami survivors exposed to high pathogen densities in soil and water, (4) destruction of critical infrastructures including health care systems causing delayed management and treatment of severe cases, (5) aggravating post-tsunami weather conditions, (6) formation of extensive potential vector breeding sites due to flooding, (7) overcrowded conditions in evacuation shelters characterized by small places, inadequate air ventilation, poor hand hygiene and dysfunction of the public health system, (8) low vaccination coverage, (9) poor personal hygiene, (10) minimum precautions against food contamination and (11) dependency of young children and weaker physical strength and resilience of elders needing assistance with daily activities. In conclusion, our study referred to potential ID following tsunamis induced after great earthquakes during the last 12 years. The establishment of strong disaster preparedness plans characterized by adequate environmental planning, resistant infrastructures and resilient health facilities is significant for the early detection, surveillance and control of emerging ID. Moreover, the establishment and the unceasing function of reliable early warning systems may help mitigate tsunami-related impact on public health.

The ecological foundations of transmission potential and vector-borne disease in urban landscapes.

PubMed

LaDeau, Shannon L; Allan, Brian F; Leisnham, Paul T; Levy, Michael Z

2015-07-01

Urban transmission of arthropod-vectored disease has increased in recent decades. Understanding and managing transmission potential in urban landscapes requires integration of sociological and ecological processes that regulate vector population dynamics, feeding behavior, and vector-pathogen interactions in these unique ecosystems. Vectorial capacity is a key metric for generating predictive understanding about transmission potential in systems with obligate vector transmission. This review evaluates how urban conditions, specifically habitat suitability and local temperature regimes, and the heterogeneity of urban landscapes can influence the biologically-relevant parameters that define vectorial capacity: vector density, survivorship, biting rate, extrinsic incubation period, and vector competence.Urban landscapes represent unique mosaics of habitat. Incidence of vector-borne disease in urban host populations is rarely, if ever, evenly distributed across an urban area. The persistence and quality of vector habitat can vary significantly across socio-economic boundaries to influence vector species composition and abundance, often generating socio-economically distinct gradients of transmission potential across neighborhoods.Urban regions often experience unique temperature regimes, broadly termed urban heat islands (UHI). Arthropod vectors are ectothermic organisms and their growth, survival, and behavior are highly sensitive to environmental temperatures. Vector response to UHI conditions is dependent on regional temperature profiles relative to the vector's thermal performance range. In temperate climates UHI can facilitate increased vector development rates while having countervailing influence on survival and feeding behavior. Understanding how urban heat island (UHI) conditions alter thermal and moisture constraints across the vector life cycle to influence transmission processes is an important direction for both empirical and modeling research.There remain persistent gaps in understanding of vital rates and drivers in mosquito-vectored disease systems, and vast holes in understanding for other arthropod vectored diseases. Empirical studies are needed to better understand the physiological constraints and socio-ecological processes that generate heterogeneity in critical transmission parameters, including vector survival and fitness. Likewise, laboratory experiments and transmission models must evaluate vector response to realistic field conditions, including variability in sociological and environmental conditions.

Entomologic and Virologic Investigation of Chikungunya, Singapore

PubMed Central

Tan, Li-Kiang; Tan, Cheong-Huat; Tan, Sharon S.Y.; Hapuarachchi, Hapuarachchige C.; Pok, Kwoon-Yong; Lai, Yee-Ling; Lam-Phua, Sai-Gek; Bucht, Göran; Lin, Raymond T.P.; Leo, Yee-Sin; Tan, Boon-Hian; Han, Hwi-Kwang; Ooi, Peng-Lim S; James, Lyn; Khoo, Seow-Poh

2009-01-01

Local transmission of chikungunya, a debilitating mosquito-borne viral disease, was first reported in Singapore in January 2008. After 3 months of absence, locally acquired Chikungunya cases resurfaced in May 2008, causing an outbreak that resulted in a total of 231 cases by September 2008. The circulating viruses were related to East, Central, and South African genotypes that emerged in the Indian Ocean region in 2005. The first local outbreak was due to a wild-type virus (alanine at codon 226 of the envelope 1 gene) and occurred in an area where Aedes aegypti mosquitoes were the primary vector. Strains isolated during subsequent outbreaks showed alanine to valine substitution (A226V) and largely spread in areas predominated by Ae. albopictus mosquitoes. These findings led to a revision of the current vector control strategy in Singapore. This report highlights the use of entomologic and virologic data to assist in the control of chikungunya in disease-endemic areas. PMID:19751586

Entomologic and virologic investigation of Chikungunya, Singapore.

PubMed

Ng, Lee-Ching; Tan, Li-Kiang; Tan, Cheong-Huat; Tan, Sharon S Y; Hapuarachchi, Hapuarachchige C; Pok, Kwoon-Yong; Lai, Yee-Ling; Lam-Phua, Sai-Gek; Bucht, Göran; Lin, Raymond T P; Leo, Yee-Sin; Tan, Boon-Hian; Han, Hwi-Kwang; Ooi, Peng-Lim S; James, Lyn; Khoo, Seow-Poh

2009-08-01

Local transmission of chikungunya, a debilitating mosquito-borne viral disease, was first reported in Singapore in January 2008. After 3 months of absence, locally acquired Chikungunya cases resurfaced in May 2008, causing an outbreak that resulted in a total of 231 cases by September 2008. The circulating viruses were related to East, Central, and South African genotypes that emerged in the Indian Ocean region in 2005. The first local outbreak was due to a wild-type virus (alanine at codon 226 of the envelope 1 gene) and occurred in an area where Aedes aegypti mosquitoes were the primary vector. Strains isolated during subsequent outbreaks showed alanine to valine substitution (A226V) and largely spread in areas predominated by Ae. albopictus mosquitoes. These findings led to a revision of the current vector control strategy in Singapore. This report highlights the use of entomologic and virologic data to assist in the control of chikungunya in disease-endemic areas.

Neurological complications of Zika virus infection.

PubMed

Carod-Artal, Francisco Javier

2018-05-01

Zika virus (ZIKV) disease is a vector-borne infectious disease transmitted by Aedes mosquitoes. Recently, ZIKV has caused outbreaks in most American countries. Areas covered: Publications about neurological complications of ZIKV infection retrieved from pubmed searchers were reviewed, and reference lists and relevant articles from review articles were also examined. Vertical/intrauterine transmission leads to congenital infection and causes microcephaly and congenital ZIKV syndrome. ZIKV preferentially infects human neural progenitor cells and triggers cell apoptosis. ZIKV RNA has been identified in foetal brain tissue and brains of microcephalic infants who died; amniotic fluid and placentas of pregnant mothers; and umbilical cord, cerebro-spinal fluid and meninges of newborns. The increase in the number of Guillain-Barre syndrome (GBS) cases during the ZIKV outbreak in the Americas provides epidemiological evidence for the link between ZIKV infection and GBS. Less frequently reported ZIKV neurological complications include encephalitis/meningoencephalitis, acute disseminated encephalomyelitis, myelitis, cerebrovascular complications (ischemic infarction; vasculopathy), seizures and encephalopathy, sensory polyneuropathy and sensory neuronopathy. Analysis of GBS incidence could serve as an epidemiological 'marker' or sentinel for ZIKV disease and other neurological complications associated to ZIKV. Expert commentary: An expanding spectrum of neurological complications associated with ZIKV infection is being recognised.

Novel Rickettsia and emergent tick-borne pathogens: A molecular survey of ticks and tick-borne pathogens in Shimba Hills National Reserve, Kenya.

PubMed

Mwamuye, Micky M; Kariuki, Edward; Omondi, David; Kabii, James; Odongo, David; Masiga, Daniel; Villinger, Jandouwe

2017-02-01

Ticks are important vectors of emerging and re-emerging zoonoses, the majority of which originate from wildlife. In recent times, this has become a global public health concern that necessitates surveillance of both known and unknown tick-borne pathogens likely to be future disease threats, as well as their tick vectors. We carried out a survey of the diversity of ticks and tick-borne pathogens in Kenya's Shimba Hills National Reserve (SHNR), an area with intensified human-livestock-wildlife interactions, where we collected 4297 questing ticks (209 adult ticks, 586 nymphs and 3502 larvae). We identified four tick species of two genera (Amblyomma eburneum, Amblyomma tholloni, Rhipicephalus maculatus and a novel Rhipicephalus sp.) based on both morphological characteristics and molecular analysis of 16S rRNA, internal transcribed spacer 2 (ITS 2) and cytochrome oxidase subunit 1 (CO1) genes. We pooled the ticks (3-8 adults, 8-15 nymphs or 30 larvae) depending on species and life-cycle stages, and screened for bacterial, arboviral and protozoal pathogens using PCR with high-resolution melting analysis and sequencing of unique melt profiles. We report the first molecular detection of Anaplasma phagocytophilum, a novel Rickettsia-like and Ehrlichia-like species, in Rh. maculatus ticks. We also detected Ehrlichia chaffeensis, Coxiella sp., Rickettsia africae and Theileria velifera in Am. eburneum ticks for the first time. Our findings demonstrate previously unidentified tick-pathogen relationships and a unique tick diversity in the SHNR that may contribute to livestock, and possibly human, morbidity in the region. This study highlights the importance of routine surveillance in similar areas to elucidate disease transmission dynamics, as a critical component to inform the development of better tick-borne disease diagnosis, prevention and control measures. Copyright © 2016 Elsevier GmbH. All rights reserved.

Clustering, climate and dengue transmission.

PubMed

Junxiong, Pang; Yee-Sin, Leo

2015-06-01

Dengue is currently the most rapidly spreading vector-borne disease, with an increasing burden over recent decades. Currently, neither a licensed vaccine nor an effective anti-viral therapy is available, and treatment largely remains supportive. Current vector control strategies to prevent and reduce dengue transmission are neither efficient nor sustainable as long-term interventions. Increased globalization and climate change have been reported to influence dengue transmission. In this article, we reviewed the non-climatic and climatic risk factors which facilitate dengue transmission. Sustainable and effective interventions to reduce the increasing threat from dengue would require the integration of these risk factors into current and future prevention strategies, including dengue vaccination, as well as the continuous support and commitment from the political and environmental stakeholders.

A novel Bluetongue virus serotype 3 strain in Tunisia, November 2016.

PubMed

Sghaier, S; Lorusso, A; Portanti, O; Marcacci, M; Orsini, M; Barbria, M E; Mahmoud, A S; Hammami, S; Petrini, A; Savini, G

2017-06-01

Since 1998, southern Europe has experienced multiple incursions of different serotypes and topotypes of Bluetongue virus, a vector-borne transmitted virus, the causative agent of Bluetongue (BT), a major disease of ruminants. Some of these incursions originated from northern Africa, likely because of wind-blown dissemination of infected midges. In this report, we describe the detection and whole genome characterization of a novel BTV-3 strain identified in a symptomatic sheep in Tunisia. Sequences were immediately deposited with the GenBank Database under Accession Nos KY432369-KY432378. Alert and preparedness are requested to face the next vector seasons in northern Africa and the potential incursion of this novel strain in southern Europe. © 2017 Blackwell Verlag GmbH.

Prevention of vector transmitted diseases with clove oil insect repellent.

PubMed

Shapiro, Rochel

2012-08-01

Vector repellent is one element in the prevention of vector-borne diseases. Families that neglect protecting their children against vectors risk their children contracting illnesses such as West Nile virus, eastern equine encephalitis, Lyme disease, malaria, dengue hemorrhagic fever, yellow fever, babesiosis, Crimean-Congo hemorrhagic fever, Rocky Mountain spotted fever, Southern tick-associated rash illness, ehrlichiosis, tick-borne relapsing fever, tularemia, and other insect and arthropod related diseases (CDC, 2011). Identification of families at risk includes screening of the underlying basis for reluctance to apply insect repellent. Nurses and physicians can participate in a positive role by assisting families to determine the proper prophylaxis by recommending insect repellent choices that are economical, safe, and easy to use. A holistic alternative might include the suggestion of clove oil in cases where families might have trepidations regarding the use of DEET on children. This article will explore the safety and effectiveness of clove oil and its use as an insect repellent. Copyright © 2012 Elsevier Inc. All rights reserved.

A Stochastic Model to Study Rift Valley Fever Persistence with Different Seasonal Patterns of Vector Abundance: New Insights on the Endemicity in the Tropical Island of Mayotte

PubMed Central

Dommergues, Laure; Zumbo, Betty; Cardinale, Eric

2015-01-01

Rift Valley fever (RVF) is a zoonotic vector-borne disease causing abortion storms in cattle and human epidemics in Africa. Our aim was to evaluate RVF persistence in a seasonal and isolated population and to apply it to Mayotte Island (Indian Ocean), where the virus was still silently circulating four years after its last known introduction in 2007. We proposed a stochastic model to estimate RVF persistence over several years and under four seasonal patterns of vector abundance. Firstly, the model predicted a wide range of virus spread patterns, from obligate persistence in a constant or tropical environment (without needing vertical transmission or reintroduction) to frequent extinctions in a drier climate. We then identified for each scenario of seasonality the parameters that most influenced prediction variations. Persistence was sensitive to vector lifespan and biting rate in a tropical climate, and to host viraemia duration and vector lifespan in a drier climate. The first epizootic peak was primarily sensitive to viraemia duration and thus likely to be controlled by vaccination, whereas subsequent peaks were sensitive to vector lifespan and biting rate in a tropical climate, and to host birth rate and viraemia duration in arid climates. Finally, we parameterized the model according to Mayotte known environment. Mosquito captures estimated the abundance of eight potential RVF vectors. Review of RVF competence studies on these species allowed adjusting transmission probabilities per bite. Ruminant serological data since 2004 and three new cross-sectional seroprevalence studies are presented. Transmission rates had to be divided by more than five to best fit observed data. Five years after introduction, RVF persisted in more than 10% of the simulations, even under this scenario of low transmission. Hence, active surveillance must be maintained to better understand the risk related to RVF persistence and to prevent new introductions. PMID:26147799

Epidemiological research on parent-child conflict in the United States: subgroup variations by place of birth and ethnicity, 2002-2013.

PubMed

Parra-Cardona, Jose Ruben; Yeh, Hsueh-Han; Anthony, James C

2017-01-01

Chronically escalated parent-child conflict has been observed to elicit maladaptive behavior and reduced psychological well-being in children and youth. In this epidemiological study, we sought to estimate the occurrence of escalated parent-child conflict for United States (US) adolescent subgroups defined by (a) ethnic self-identification, and (b) nativity (US-born versus foreign-born). US study populations of 12-to-17-year-olds were sampled, recruited, and assessed for the National Surveys on Drug Use and Health (NSDUH), 2002-2013 ( n  = 111, 129). Analysis-weighted contingency table analyses contrasted US-born versus foreign-born who self-identified as: (a) Hispanic, (b) non-Hispanic African-American, (c) non-Hispanic Asian, and (c) non-Hispanic White. Frequently escalated parent-child conflict was most prevalent among US-born non-Hispanic White adolescents, from 18% at age 12 (95% CI [17.6%, 18.9%]) to 29% at age 17 (95% CI [28.3%, 29.7%]), followed by US-born Hispanic and non-Hispanic Asian children. Estimated prevalence proportions were markedly lower for African-American children, from 8% at age 12 (95% CI [6.8, 8.5]) to 16% at age 17 (95% CI [14.3, 16.7]). Broad and sometimes overlapping CI indicate that larger sample sizes are needed for complete evaluation of an apparent excess occurrence of frequent parent-child conflict among US-born versus foreign-born. Nonetheless, in the larger subgroups, the US-born show a clear excess occurrence of frequent parent-child conflict. For example, US-born Mexican children have 1.7 times higher odds of experiencing frequent parent-child conflict than foreign-born Mexican children (OR = 1.7, 95% CI [1.5, 2.0], p -value < 0.001). The main discovery from this multi-ethnic sample investigation is a rank-ordering of parent-child conflict prevalence estimates from high (non-Hispanic White) to low (non-Hispanic African-American). The pattern also suggests a possibly generalizable excess associated with US-born sub-groups. The epidemiological estimates presented here merit attention in future cross-cultural research focused on parent-child conflict.

Epidemiological research on parent–child conflict in the United States: subgroup variations by place of birth and ethnicity, 2002–2013

PubMed Central

Yeh, Hsueh-Han; Anthony, James C.

2017-01-01

Background Chronically escalated parent–child conflict has been observed to elicit maladaptive behavior and reduced psychological well-being in children and youth. In this epidemiological study, we sought to estimate the occurrence of escalated parent–child conflict for United States (US) adolescent subgroups defined by (a) ethnic self-identification, and (b) nativity (US-born versus foreign-born). Methods US study populations of 12-to-17-year-olds were sampled, recruited, and assessed for the National Surveys on Drug Use and Health (NSDUH), 2002–2013 (n = 111, 129). Analysis-weighted contingency table analyses contrasted US-born versus foreign-born who self-identified as: (a) Hispanic, (b) non-Hispanic African-American, (c) non-Hispanic Asian, and (c) non-Hispanic White. Results Frequently escalated parent–child conflict was most prevalent among US-born non-Hispanic White adolescents, from 18% at age 12 (95% CI [17.6%, 18.9%]) to 29% at age 17 (95% CI [28.3%, 29.7%]), followed by US-born Hispanic and non-Hispanic Asian children. Estimated prevalence proportions were markedly lower for African-American children, from 8% at age 12 (95% CI [6.8, 8.5]) to 16% at age 17 (95% CI [14.3, 16.7]). Broad and sometimes overlapping CI indicate that larger sample sizes are needed for complete evaluation of an apparent excess occurrence of frequent parent-child conflict among US-born versus foreign-born. Nonetheless, in the larger subgroups, the US-born show a clear excess occurrence of frequent parent-child conflict. For example, US-born Mexican children have 1.7 times higher odds of experiencing frequent parent-child conflict than foreign-born Mexican children (OR = 1.7, 95% CI [1.5, 2.0], p-value < 0.001). Discussion The main discovery from this multi-ethnic sample investigation is a rank-ordering of parent-child conflict prevalence estimates from high (non-Hispanic White) to low (non-Hispanic African-American). The pattern also suggests a possibly generalizable excess associated with US-born sub-groups. The epidemiological estimates presented here merit attention in future cross-cultural research focused on parent-child conflict. PMID:28149684

Zika virus: a new arboviral public health problem.

PubMed

Demir, Tulin; Kilic, Selcuk

2016-11-01

Zika virus (ZIKV) is a single-stranded RNA virus in the Flaviviridae family and transmitted to human through infected mosquitos (Aedes aegypti and Aedes albopictus). Virus is closely related with other flaviviruses; dengue virus, yellow fever virus, West Nile virus, and Japanese encephalitis virus phylogenetically. Due to the possible relationship between virus and clinical features including microcephaly, ventricule, and eye deformities, Guillain-Barre syndrome increases the interest on this virus gradually. Along with the vector-borne transmission, exposure via blood transfusion and sexual contact are further concerns. Since December 2015, CDC reported 440.000-1.300.000 possible cases in Brazil and as of 19 January 2016, El Salvador, Venezuela, Colombia, Brazil, Surinam, French Guana, Honduras, Mexico, and Panama are the countries with active epidemic. CDC recommends ZIKV screening for all pregnants including asymptomatic cases those living in the active epidemic areas. Recently, virus is detected in the USA and most European countries including UK, Netherlands, Denmark, Switzerland, and Italy as a travel-associated infection. Owing to the changing world with increased capabilities for transportation globally, this vector-borne infection represents a valuable marker for the ability of spreading of any infection from its original area that it was first seen. In this review, we summarized the up-to-date data and reports in terms of the importance of the ZIKV infection in the public health.

Status of pesticide management in the practice of vector control: a global survey in countries at risk of malaria or other major vector-borne diseases.

PubMed

van den Berg, Henk; Hii, Jeffrey; Soares, Agnes; Mnzava, Abraham; Ameneshewa, Birkinesh; Dash, Aditya P; Ejov, Mikhail; Tan, Soo Hian; Matthews, Graham; Yadav, Rajpal S; Zaim, Morteza

2011-05-14

It is critical that vector control pesticides are used for their acceptable purpose without causing adverse effects on health and the environment. This paper provides a global overview of the current status of pesticides management in the practice of vector control. A questionnaire was distributed to WHO member states and completed either by the director of the vector-borne disease control programme or by the national manager for vector control. In all, 113 countries responded to the questionnaire (80% response rate), representing 94% of the total population of the countries targeted. Major gaps were evident in countries in pesticide procurement practices, training on vector control decision making, certification and quality control of pesticide application, monitoring of worker safety, public awareness programmes, and safe disposal of pesticide-related waste. Nevertheless, basic conditions of policy and coordination have been established in many countries through which the management of vector control pesticides could potentially be improved. Most countries responded that they have adopted relevant recommendations by the WHO. Given the deficiencies identified in this first global survey on public health pesticide management and the recent rise in pesticide use for malaria control, the effectiveness and safety of pesticide use are being compromised. This highlights the urgent need for countries to strengthen their capacity on pesticide management and evidence-based decision making within the context of an integrated vector management approach.

Status of pesticide management in the practice of vector control: a global survey in countries at risk of malaria or other major vector-borne diseases

PubMed Central

2011-01-01

Background It is critical that vector control pesticides are used for their acceptable purpose without causing adverse effects on health and the environment. This paper provides a global overview of the current status of pesticides management in the practice of vector control. Methods A questionnaire was distributed to WHO member states and completed either by the director of the vector-borne disease control programme or by the national manager for vector control. In all, 113 countries responded to the questionnaire (80% response rate), representing 94% of the total population of the countries targeted. Results Major gaps were evident in countries in pesticide procurement practices, training on vector control decision making, certification and quality control of pesticide application, monitoring of worker safety, public awareness programmes, and safe disposal of pesticide-related waste. Nevertheless, basic conditions of policy and coordination have been established in many countries through which the management of vector control pesticides could potentially be improved. Most countries responded that they have adopted relevant recommendations by the WHO. Conclusions Given the deficiencies identified in this first global survey on public health pesticide management and the recent rise in pesticide use for malaria control, the effectiveness and safety of pesticide use are being compromised. This highlights the urgent need for countries to strengthen their capacity on pesticide management and evidence-based decision making within the context of an integrated vector management approach. PMID:21569601

Rhabdomyolysis After Cooked Seafood Consumption (Haff Disease) in the United States vs China

PubMed Central

Diaz, James H.

2015-01-01

Background Haff disease is a syndrome of myalgia and rhabdomyolysis that occurs after eating cooked seafood. Methods For this descriptive analytical article, a literature search identified the scientific articles on Haff disease and/or rhabdomyolysis after eating cooked seafood in the United States and China. Analysis of those articles focused on identifying the seafood vectors of Haff disease, describing the most commonly recurring clinical and laboratory manifestations of Haff disease, and comparing the Haff disease toxidrome with other similar seafood-borne toxidromes. Statistically significant differences were determined using unpaired t tests and Fisher exact tests. Results Twenty-nine confirmed cases of Haff disease were identified in the United States, and 60 cases were identified in China during 1984-2014. Most of the US cases followed consumption of buffalo fish, and most of the Chinese cases followed consumption of freshwater pomfret. However, Haff disease also followed consumption of the same species of boiled crayfish (Procambarus clarkii) in the United States (n=9) and China (n=6). US patients with crayfish-transmitted Haff disease reported significantly more nausea with and without vomiting, chest pain, body and back pain, dyspnea, and diaphoresis than the Chinese patients and were more frequently misdiagnosed as having myocardial infarctions. Conclusion The bioaccumulation of a new, heat-stable freshwater and/or brackish/saltwater algal toxin, similar to palytoxin but primarily myotoxic and not neurotoxic, is suspected of causing Haff disease. At present, only the rapid identification of the seafood vectors of Haff disease will limit disease outbreaks and prevent further cases. PMID:26130980

Vector-borne diseases on Fire Island, New York (Fire Island National Seashore Science Synthesis Paper)

USGS Publications Warehouse

Ginsberg, H.S.

2005-01-01

This paper discusses eleven tick-borne and five mosquito-borne pathogens that are known to occur at FIlS, or could potentially occur. The potential for future occurrence, and ecological factors that influence occurrence, are assessed for each disease. Lyme disease is the most common vector-borne disease on Fire Island. The Lyme spirochete, Borrelia burgdorferi, is endemic in local tick and wildlife populations. Public education, personal precautions against tick bite, and prompt treatment of early-stage infections can help manage the risk of Lyme disease on Fire Island. The pathogens that cause Human Monocytic Ehrlichiosis and Tularemia have been isolated from ticks or wildlife on Fire Island, and conditions suggest that other tickborne diseases (including Babesiosis, Rocky Mountain Spotted Fever, and Human Granulocytic Ehrlichiosis) might also occur, but these are far less common than Lyme disease, if present. West Nile Virus (WNV) is the primary mosquito- borne human pathogen that is known to occur on Fire Island. Ecological conditions and recent epizootiological events suggest that WNV occurs in foci that can shift from year to year. Therefore, a surveillance program with appropriate responses to increasing epizootic activity can help manage the risk of WNV transmission on Fire Island.

Climate change in the North American Arctic: A one health perspective

USDA-ARS?s Scientific Manuscript database

Climate change is expected to increase the prevalence of acute and chronic diseases among human and animal populations within the Arctic and sub-Arctic latitudes of North America. Warmer temperatures are expected to increase disease risks from food-borne pathogens, water-borne diseases, and vector-...

Solid Waste/Disease Relationships, A Literature Survey.

ERIC Educational Resources Information Center

Hanks, Thrift G.

Presented is a comprehensive survey of the literature on the relationships between disease and solid wastes. Diseases are grouped on the basis of waste type or disease vector, such as chemical waste, human fecal waste, animal fecal waste, rodent-borne disease, mosquito-borne disease and miscellaneous communicable disease. The following format is…

Mathematical analysis of a power-law form time dependent vector-borne disease transmission model.

PubMed

Sardar, Tridip; Saha, Bapi

2017-06-01

In the last few years, fractional order derivatives have been used in epidemiology to capture the memory phenomena. However, these models do not have proper biological justification in most of the cases and lack a derivation from a stochastic process. In this present manuscript, using theory of a stochastic process, we derived a general time dependent single strain vector borne disease model. It is shown that under certain choice of time dependent transmission kernel this model can be converted into the classical integer order system. When the time-dependent transmission follows a power law form, we showed that the model converted into a vector borne disease model with fractional order transmission. We explicitly derived the disease-free and endemic equilibrium of this new fractional order vector borne disease model. Using mathematical properties of nonlinear Volterra type integral equation it is shown that the unique disease-free state is globally asymptotically stable under certain condition. We define a threshold quantity which is epidemiologically known as the basic reproduction number (R 0 ). It is shown that if R 0 > 1, then the derived fractional order model has a unique endemic equilibrium. We analytically derived the condition for the local stability of the endemic equilibrium. To test the model capability to capture real epidemic, we calibrated our newly proposed model to weekly dengue incidence data of San Juan, Puerto Rico for the time period 30th April 1994 to 23rd April 1995. We estimated several parameters, including the order of the fractional derivative of the proposed model using aforesaid data. It is shown that our proposed fractional order model can nicely capture real epidemic. Copyright © 2017 Elsevier Inc. All rights reserved.

Engaging scientists: An online survey exploring the experience of innovative biotechnological approaches to controlling vector-borne diseases.

PubMed

Boëte, Christophe; Beisel, Uli; Reis Castro, Luísa; Césard, Nicolas; Reeves, R Guy

2015-08-10

Pioneering technologies (e.g., nanotechnology, synthetic biology or climate engineering) are often associated with potential new risks and uncertainties that can become sources of controversy. The communication of information during their development and open exchanges between stakeholders is generally considered a key issue in their acceptance. While the attitudes of the public to novel technologies have been widely considered there has been relatively little investigation of the perceptions and awareness of scientists working on human or animal diseases transmitted by arthropods. Consequently, we conducted a global survey on 1889 scientists working on aspects of vector-borne diseases, exploring, under the light of a variety of demographic and professional factors, their knowledge and awareness of an emerging biotechnology that has the potential to revolutionize the control of pest insect populations. Despite extensive media coverage of key developments (including releases of manipulated mosquitoes into human communities) this has in only one instance resulted in scientist awareness exceeding 50% on a national or regional scale. We document that awareness of pioneering releases significantly relied on private communication sources that were not equally accessible to scientists from countries with endemic vector-borne diseases (dengue and malaria). In addition, we provide quantitative analysis of the perceptions and knowledge of specific biotechnological approaches to controlling vector-borne disease, which are likely to impact the way in which scientists around the world engage in the debate about their value. Our results indicate that there is scope to strengthen already effective methods of communication, in addition to a strong demand by scientists (expressed by 79.9% of respondents) to develop new, creative modes of public engagement.

Ectoparasites and other epifaunistic arthropods of sympatric cotton mice and golden mice: comparisons and implications for vector-borne zoonotic diseases.

PubMed

Durden, Lance A; Polur, Ram N; Nims, Todd; Banks, Craig W; Oliver, James H

2004-12-01

Ectoparasite and epifaunistic arthropod biodiversity and infestation parameters were compared between 2 sympatric small rodent species, the cotton mouse (Peromyscus gossypinus (Le Conte)) and golden mouse (Ochrotomys nuttalli (Harlan)), in southern Georgia from 1992 to 2003. Because the cotton mouse is known to be a reservoir of more vector-borne zoonotic pathogens than the golden mouse, we hypothesized that it would be parasitized by more ectoparasites that are known to be vectors of these pathogens. Cotton mice (n = 202) were parasitized by 19 species of arthropods, whereas golden mice (n = 46) were parasitized by 12 species. Eleven species of arthropods were recovered from both host species, whereas 7 were recorded only from cotton mice, and 1 species only from golden mice. Infestation prevalences (percent of mice parasitized) were significantly higher for 1 species of arthropod (the tropical rat mite Ornithonyssus bacoti (Hirst)) infesting cotton mice and for 4 species (the flea Peromyscopsylla scotti Fox and the mites Glycyphagus hypudaei Koch, Androlaelaps casalis (Berlese), and Androlaelaps fahrenholzi (Berlese)) infesting golden mice. Mean intensities (mean per infested mouse) were significantly higher for 2 species (the flea Orchopeas leucopus (Baker) and the blacklegged tick Ixodes scapularis Say) infesting cotton mice and for 2 species (G. hypudaei and A. fahrenholzi) infesting golden mice. Ectoparasites that are known to be vectors of zoonotic pathogens were significantly more common on cotton mice than on golden mice. These ectoparasites included the rhopalopsyllid flea Polygenis gwyni (Fox), a vector of the agent of murine typhus; I. scapularis, the principal vector of the agents of Lyme borreliosis, human granulocytic ehrlichiosis, and human babesiosis; and O. bacoti, a laboratory vector of several zoonotic pathogens. However, 2 species of ixodid ticks that can transmit zoonotic pathogens were recovered from both host species. These were the American dog tick Dermacentor variabilis (Say), the principal vector of the agent of Rocky Mountain spotted fever in eastern North America, and Ixodes minor Neumann, an enzootic vector of the agent of Lyme borreliosis. Overall, the cotton mouse was parasitized by significantly more ectoparasites that are known to be vectors of zoonotic pathogens than was the golden mouse. These data support the hypothesis that the cotton mouse has greater epidemiological importance for zoonotic vector-borne pathogen transmission than does the golden mouse.

House-to-house human movement drives dengue virus transmission

PubMed Central

Stoddard, Steven T.; Forshey, Brett M.; Morrison, Amy C.; Paz-Soldan, Valerie A.; Vazquez-Prokopec, Gonzalo M.; Astete, Helvio; Reiner, Robert C.; Vilcarromero, Stalin; Elder, John P.; Halsey, Eric S.; Kochel, Tadeusz J.; Kitron, Uriel; Scott, Thomas W.

2013-01-01

Dengue is a mosquito-borne disease of growing global health importance. Prevention efforts focus on mosquito control, with limited success. New insights into the spatiotemporal drivers of dengue dynamics are needed to design improved disease-prevention strategies. Given the restricted range of movement of the primary mosquito vector, Aedes aegypti, local human movements may be an important driver of dengue virus (DENV) amplification and spread. Using contact-site cluster investigations in a case-control design, we demonstrate that, at an individual level, risk for human infection is defined by visits to places where contact with infected mosquitoes is likely, independent of distance from the home. Our data indicate that house-to-house human movements underlie spatial patterns of DENV incidence, causing marked heterogeneity in transmission rates. At a collective level, transmission appears to be shaped by social connections because routine movements among the same places, such as the homes of family and friends, are often similar for the infected individual and their contacts. Thus, routine, house-to-house human movements do play a key role in spread of this vector-borne pathogen at fine spatial scales. This finding has important implications for dengue prevention, challenging the appropriateness of current approaches to vector control. We argue that reexamination of existing paradigms regarding the spatiotemporal dynamics of DENV and other vector-borne pathogens, especially the importance of human movement, will lead to improvements in disease prevention. PMID:23277539

Exploiting mosquito sugar feeding to detect mosquito-borne pathogens

PubMed Central

Hall-Mendelin, Sonja; Ritchie, Scott A.; Johansen, Cheryl A.; Zborowski, Paul; Cortis, Giles; Dandridge, Scott; Hall, Roy A.; van den Hurk, Andrew F.

2010-01-01

Arthropod-borne viruses (arboviruses) represent a global public health problem, with dengue viruses causing millions of infections annually, while emerging arboviruses, such as West Nile, Japanese encephalitis, and chikungunya viruses have dramatically expanded their geographical ranges. Surveillance of arboviruses provides vital data regarding their prevalence and distribution that may be utilized for biosecurity measures and the implementation of disease control strategies. However, current surveillance methods that involve detection of virus in mosquito populations or sero-conversion in vertebrate hosts are laborious, expensive, and logistically problematic. We report a unique arbovirus surveillance system to detect arboviruses that exploits the process whereby mosquitoes expectorate virus in their saliva during sugar feeding. In this system, infected mosquitoes captured by CO2-baited updraft box traps are allowed to feed on honey-soaked nucleic acid preservation cards within the trap. The cards are then analyzed for expectorated virus using real-time reverse transcription-PCR. In field trials, this system detected the presence of Ross River and Barmah Forest viruses in multiple traps deployed at two locations in Australia. Viral RNA was preserved for at least seven days on the cards, allowing for long-term placement of traps and continuous collection of data documenting virus presence in mosquito populations. Furthermore no mosquito handling or processing was required and cards were conveniently shipped to the laboratory overnight. The simplicity and efficacy of this approach has the potential to transform current approaches to vector-borne disease surveillance by streamlining the monitoring of pathogens in vector populations. PMID:20534559

Pathogenic landscapes: Interactions between land, people, disease vectors, and their animal hosts

PubMed Central

2010-01-01

Background Landscape attributes influence spatial variations in disease risk or incidence. We present a review of the key findings from eight case studies that we conducted in Europe and West Africa on the impact of land changes on emerging or re-emerging vector-borne diseases and/or zoonoses. The case studies concern West Nile virus transmission in Senegal, tick-borne encephalitis incidence in Latvia, sandfly abundance in the French Pyrenees, Rift Valley Fever in the Ferlo (Senegal), West Nile Fever and the risk of malaria re-emergence in the Camargue, and rodent-borne Puumala hantavirus and Lyme borreliosis in Belgium. Results We identified general principles governing landscape epidemiology in these diverse disease systems and geographic regions. We formulated ten propositions that are related to landscape attributes, spatial patterns and habitat connectivity, pathways of pathogen transmission between vectors and hosts, scale issues, land use and ownership, and human behaviour associated with transmission cycles. Conclusions A static view of the "pathogenecity" of landscapes overlays maps of the spatial distribution of vectors and their habitats, animal hosts carrying specific pathogens and their habitat, and susceptible human hosts and their land use. A more dynamic view emphasizing the spatial and temporal interactions between these agents at multiple scales is more appropriate. We also highlight the complementarity of the modelling approaches used in our case studies. Integrated analyses at the landscape scale allows a better understanding of interactions between changes in ecosystems and climate, land use and human behaviour, and the ecology of vectors and animal hosts of infectious agents. PMID:20979609

Reflections on the Anopheles gambiae genome sequence, transgenic mosquitoes and the prospect for controlling malaria and other vector borne diseases.

PubMed

Tabachnick, Walter J

2003-09-01

The completion of the Anopheles gambiae Giles genome sequencing project is a milestone toward developing more effective strategies in reducing the impact of malaria and other vector borne diseases. The successes in developing transgenic approaches using mosquitoes have provided another essential new tool for further progress in basic vector genetics and the goal of disease control. The use of transgenic approaches to develop refractory mosquitoes is also possible. The ability to use genome sequence to identify genes, and transgenic approaches to construct refractory mosquitoes, has provided the opportunity that with the future development of an appropriate genetic drive system, refractory transgenes can be released into vector populations leading to nontransmitting mosquitoes. An. gambiae populations incapable of transmitting malaria. This compelling strategy will be very difficult to achieve and will require a broad substantial research program for success. The fundamental information that is required on genome structure, gene function and environmental effects on genetic expression are largely unknown. The ability to predict gene effects on phenotype is rudimentary, particularly in natural populations. As a result, the release of a refractory transgene into natural mosquito populations is imprecise and there is little ability to predict unintended consequences. The new genetic tools at hand provide opportunities to address an array of important issues, many of which can have immediate impact on the effectiveness of a host of strategies to control vector borne disease. Transgenic release approaches represent only one strategy that should be pursued. A balanced research program is required.

Habitat Suitability Model for the Distribution of Ixodes scapularis (Acari: Ixodidae) in Minnesota

PubMed Central

Johnson, T. L.; Bjork, J. K. H.; Neitzel, D. F.; Dorr, F. M.; Schiffman, E. K.; Eisen, R. J.

2016-01-01

Ixodes scapularis Say, the black-legged tick, is the primary vector in the eastern United States of several pathogens causing human diseases including Lyme disease, anaplasmosis, and babesiosis. Over the past two decades, I. scapularis-borne diseases have increased in incidence as well as geographic distribution. Lyme disease exists in two major foci in the United States, one encompassing northeastern states and the other in the Upper Midwest. Minnesota represents a state with an appreciable increase in counties reporting I. scapularis-borne illnesses, suggesting geographic expansion of vector populations in recent years. Recent tick distribution records support this assumption. Here, we used those records to create a fine resolution, subcounty-level distribution model for I. scapularis using variable response curves in addition to tests of variable importance. The model identified 19% of Minnesota as potentially suitable for establishment of the tick and indicated with high accuracy (AUC = 0.863) that the distribution is driven by land cover type, summer precipitation, maximum summer temperatures, and annual temperature variation. We provide updated records of established populations near the northwestern species range limit and present a model that increases our understanding of the potential distribution of I. scapularis in Minnesota. PMID:27026161

The rise of neglected tropical diseases in the "new Texas".

PubMed

Hotez, Peter J

2018-01-01

Within the last five years, the State of Texas has experienced either transmission or outbreaks of Ebola, chikungunya, West Nile, and Zika virus infections. Autochthonous transmission of neglected parasitic and bacterial diseases has also become increasingly reported. The rise of such emerging and neglected tropical diseases (NTDs) has not occurred by accident but instead reflects rapidly evolving changes and shifts in a "new" Texas beset by modern and globalizing forces that include rapid expansions in population together with urbanization and human migrations, altered transportation patterns, climate change, steeply declining vaccination rates, and a new paradigm of poverty known as "blue marble health." Summarized here are the major NTDs now affecting Texas. In addition to the vector-borne viral diseases highlighted above, there also is a high level of parasitic infections, including Chagas disease, trichomoniasis, and possibly leishmaniasis and toxocariasis, as well as typhus-group rickettsiosis, a vector-borne bacterial infection. I also highlight some of the key shifts in emerging and neglected disease patterns, partly due to an altered and evolving economic and ecological landscape in the new Texas, and provide some preliminary disease burden estimates for the major prevalent and incident NTDs.

Analysis of the El Niño/La Niña-Southern Oscillation variability and malaria in the Estado Sucre, Venezuela.

PubMed

Delgado-Petrocelli, Laura; Córdova, Karenia; Camardiel, Alberto; Aguilar, Víctor H; Hernández, Denise; Ramos, Santiago

2012-09-01

The last decade has seen an unprecedented, worldwide acceleration of environmental and climate changes. These processes impact the dynamics of natural systems, which include components associated with human communities such as vector-borne diseases. The dynamics of environmental and climate variables, altered by global change as reported by the Intergovernmental Panel on Climate Change, affect the distribution of many tropical diseases. Complex systems, e.g. the El Niño/La Niña-Southern Oscillation (ENSO), in which environmental variables operate synergistically, can provoke the reemergence and emergence of vector-borne diseases at new sites. This research investigated the influence of ENSO events on malaria incidence by determining the relationship between climate variations, expressed as warm, cold and neutral phases, and their relation to the number of malaria cases in some north-eastern municipalities of Venezuela (Estado Sucre) during the period 1990-2000. Significant differences in malaria incidence were found, particularly in the La Niña ENSO phases (cold) of moderate intensity. These findings should be taken into account for surveillance and control in the future as they shed light on important indicators that can lead to reduced vulnerability to malaria.

Complete genomic sequence of Powassan virus: evaluation of genetic elements in tick-borne versus mosquito-borne flaviviruses.

PubMed

Mandl, C W; Holzmann, H; Kunz, C; Heinz, F X

1993-05-01

The complete nucleotide sequence of the positive-stranded RNA genome of the tick-borne flavivirus Powassan (10,839 nucleotides) was elucidated and the amino acid sequence of all viral proteins was derived. Based on this sequence as well as serological data, Powassan virus represents the most divergent member of the tick-borne serocomplex within the genus flaviviruses, family Flaviviridae. The primary nucleotide sequence and potential RNA secondary structures of the Powassan virus genome as well as the protein sequences and the reactivities of the virion with a panel of monoclonal antibodies were compared to other tick-borne and mosquito-borne flaviviruses. These analyses corroborated significant differences between tick-borne and mosquito-borne flaviviruses, but also emphasized structural elements that are conserved among both vector groups. The comparisons among tick-borne flaviviruses revealed conserved sequence elements that might represent important determinants of the tick-borne flavivirus phenotype.

Community-Based Entomological Surveillance Reveals Urban Foci of Chagas Disease Vectors in Sobral, State of Ceará, Northeastern Brazil.

PubMed

Parente, Cynara Carvalho; Bezerra, Fernando S M; Parente, Plutarco I; Dias-Neto, Raimundo V; Xavier, Samanta C C; Ramos, Alberto N; Carvalho-Costa, Filipe A; Lima, Marli M

2017-01-01

The aim of this work was to explore the potential risk of vector-borne Chagas disease in urban districts in northeastern Brazil, by analyzing the spatiotemporal distributions and natural infection rates with Trypanosoma cruzi of triatomine species captured in recent years. The main motivation of this work was an acute human case of Chagas disease reported in 2008 in the municipality of Sobral. We analyzed data from community-based entomological surveillance carried out from 2010 to 2014. Triatomine natural T. cruzi infection was assessed by examination of insect feces by optical microscopy. Sites of triatomine capture were georeferenced through Google Earth and analyzed with ArcGIS. A total of 191 triatomines were collected, consisting of 82.2% Triatoma pseudomaculata, 7.9% Rhodnius nasutus, 5.8% T. brasiliensis, 3.7% Panstrongylus lutzi, and 0.5% P. megistus, with an overall natural infection index of 17.8%. Most infestations were reported in the districts of Dom José (36.2%), Padre Palhano (24.7%), and Alto do Cristo (10.6%). The overwhelming majority of insects (185/96.9%) were captured inside houses, and most insects tended to be collected in intermittent peaks. Moreover, captured triatomines tended to constitute colonies. The acute case reported in 2008 was found to be situated within a T. pseudomaculata hotspot. The triatomine collection events carried out by dwellers were aggregated in time and space into distinct foci, suggesting that insects are intermittently and artificially introduced into the city, possibly via accidental migration from their natural reservoirs. The relatively high T. cruzi infection rate indicates considerable circulation of the parasite in these areas, increasing the risk of vector-borne Chagas disease infection. These data suggest a need to strengthen epidemiological surveillance and integrate appropriate control actions targeting triatomines, T. cruzi reservoirs, and human populations. Our data also identify Chagas disease transmission as a hazard in urban areas of Sobral.

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

Meagher, Robert J.; Ball, Cameron Scott; Langevin, Stanley A.

In this study, collection of mosquitoes and testing for vector-borne viruses is a key surveillance activity that directly influences the vector control efforts of public health agencies, including determining when and where to apply insecticides. Vector control districts in California routinely monitor for three human pathogenic viruses including West Nile virus (WNV), Western equine encephalitis virus (WEEV), and St. Louis encephalitis virus (SLEV). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) offers highly sensitive and specific detection of these three viruses in a single multiplex reaction, but this technique requires costly, specialized equipment that is generally only available in centralized publicmore » health laboratories. We report the use of reverse transcription loop-mediated isothermal amplification (RT-LAMP) to detect WNV, WEEV, and SLEV RNA extracted from pooled mosquito samples collected in California, including novel primer sets for specific detection of WEEV and SLEV, targeting the nonstructural protein 4 (nsP4) gene of WEEV and the 3’ untranslated region (3’-UTR) of SLEV. Our WEEV and SLEV RT-LAMP primers allowed detection of <0.1 PFU/reaction of their respective targets in <30 minutes, and exhibited high specificity without cross reactivity when tested against a panel of alphaviruses and flaviviruses. Furthermore, the SLEV primers do not cross-react with WNV, despite both viruses being closely related members of the Japanese encephalitis virus complex. The SLEV and WEEV primers can also be combined in a single RT-LAMP reaction, with discrimination between amplicons by melt curve analysis. Although RT-qPCR is approximately one order of magnitude more sensitive than RT-LAMP for all three targets, the RT-LAMP technique is less instrumentally intensive than RT-qPCR and provides a more cost-effective method of vector-borne virus surveillance.« less

Insecticide-treated durable wall lining (ITWL): future prospects for control of malaria and other vector-borne diseases.

PubMed

Messenger, Louisa A; Rowland, Mark

2017-05-22

While long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the cornerstones of malaria vector control throughout sub-Saharan Africa, there is an urgent need for the development of novel insecticide delivery mechanisms to sustain and consolidate gains in disease reduction and to transition towards malaria elimination and eradication. Insecticide-treated durable wall lining (ITWL) may represent a new paradigm for malaria control as a potential complementary or alternate longer-lasting intervention to IRS. ITWL can be attached to inner house walls, remain efficacious over multiple years and overcome some of the operational constraints of first-line control strategies, specifically nightly behavioural compliance required of LLINs and re-current costs and user fatigue associated with IRS campaigns. Initial experimental hut trials of insecticide-treated plastic sheeting reported promising results, achieving high levels of vector mortality, deterrence and blood-feeding inhibition, particularly when combined with LLINs. Two generations of commercial ITWL have been manufactured to date containing either pyrethroid or non-pyrethroid formulations. While some Phase III trials of these products have demonstrated reductions in malaria incidence, further large-scale evidence is still required before operational implementation of ITWL can be considered either in a programmatic or more targeted community context. Qualitative studies of ITWL have identified aesthetic value and observable entomological efficacy as key determinants of household acceptability. However, concerns have been raised regarding installation feasibility and anticipated cost-effectiveness. This paper critically reviews ITWL as both a putative mechanism of house improvement or more conventional intervention and discusses its future prospects as a method for controlling malaria and other vector-borne diseases.

Surveillance for Western Equine Encephalitis, St. Louis Encephalitis, and West Nile Viruses Using Reverse Transcription Loop-Mediated Isothermal Amplification

PubMed Central

Wheeler, Sarah S.; Ball, Cameron S.; Langevin, Stanley A.; Fang, Ying; Coffey, Lark L.; Meagher, Robert J.

2016-01-01

Collection of mosquitoes and testing for vector-borne viruses is a key surveillance activity that directly influences the vector control efforts of public health agencies, including determining when and where to apply insecticides. Vector control districts in California routinely monitor for three human pathogenic viruses including West Nile virus (WNV), Western equine encephalitis virus (WEEV), and St. Louis encephalitis virus (SLEV). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) offers highly sensitive and specific detection of these three viruses in a single multiplex reaction, but this technique requires costly, specialized equipment that is generally only available in centralized public health laboratories. We report the use of reverse transcription loop-mediated isothermal amplification (RT-LAMP) to detect WNV, WEEV, and SLEV RNA extracted from pooled mosquito samples collected in California, including novel primer sets for specific detection of WEEV and SLEV, targeting the nonstructural protein 4 (nsP4) gene of WEEV and the 3’ untranslated region (3’-UTR) of SLEV. Our WEEV and SLEV RT-LAMP primers allowed detection of <0.1 PFU/reaction of their respective targets in <30 minutes, and exhibited high specificity without cross reactivity when tested against a panel of alphaviruses and flaviviruses. Furthermore, the SLEV primers do not cross-react with WNV, despite both viruses being closely related members of the Japanese encephalitis virus complex. The SLEV and WEEV primers can also be combined in a single RT-LAMP reaction, with discrimination between amplicons by melt curve analysis. Although RT-qPCR is approximately one order of magnitude more sensitive than RT-LAMP for all three targets, the RT-LAMP technique is less instrumentally intensive than RT-qPCR and provides a more cost-effective method of vector-borne virus surveillance. PMID:26807734

Canine vector-borne co-infections: Ehrlichia canis and Hepatozoon canis in the same host monocytes.

PubMed

Baneth, Gad; Harrus, Shimon; Gal, Arnon; Aroch, Itamar

2015-02-28

The protozoon Hepatozoon canis and the rickettsia Ehrlichia canis are tick-borne pathogens, transmitted by Rhipicephalus sanguineus, which cause canine hepatozoonosis and canine monocytic ehrlichiosis, respectively. Co-infection of the same host monocytes with H. canis and E. canis confirmed by molecular characterization of the infecting agents and quantitative assessment of co-infected cells is described for the first time in three naturally-infected dogs. Blood smear evaluation indicated that at least 50% of the leukocytes infected with H. canis gamonts contained E. canis morulae. Co-infection of the same host cell demonstrated in this report suggests that infection with one pathogen may permit or enhance invasion or prolonged cellular survival of the other. Copyright © 2014 Elsevier B.V. All rights reserved.

First report of canine ocular thelaziosis in the Muntenia Region, Romania.

PubMed

Tudor, Poliana; Bădicu, Adina; Mateescu, Romaniţa; Tudor, Niculae; Mateescu, Cosmin; Ionaşcu, Iuliana

2016-04-01

Ocular thelaziosis by Thelazia callipaeda is a vector-borne disease that infects domestic and wild carnivores as well as humans. In this paper, we present two cases of ocular thelaziosis in dogs that had never traveled outside Romania. Both presented with moderate conjunctivitis and ocular discharge. In total, 41 adult nematodes were removed from the conjunctival sacs of both dogs; these were identified via morphology as T. callipaeda. To the best of our knowledge, this is the first report of canine ocular thelaziosis caused by T. callipaeda from the Muntenia Region of Romania.

Dengue fever virus in Pakistan: effects of seasonal pattern and temperature change on distribution of vector and virus.

PubMed

Bostan, Nazish; Javed, Sundus; Nabgha-E-Amen; Eqani, Syed Ali Musstjab Akber Shah; Tahir, Faheem; Bokhari, Habib

2017-01-01

Dengue fever is regarded as one of the most prominent emerging arboviral infections in Pakistan since its first epidemic almost 2 decades ago. Interplay between potential vectors, susceptible host, and lax environmental conditions may promote the infection, leading to an epidemic. These factors may indeed have played a major role in the spread of the disease in the country, which was limited to Karachi till 2006. With recent natural disasters such as the earthquake in 2005 and flooding in 2010, 2011 and 2012, numbers of vector-borne diseases and outbreaks including dengue fever are on the rise in Pakistan. Therefore, it is a major concern for health sector workers and of utmost importance to have some understanding of the factors affecting disease outbreak for better risk assessment in the region. In the following report we review the climatic as well as host- and vector-associated factors involved in the outbreak of dengue epidemics in Pakistan and highlight high-risk zones in the country. Copyright © 2016 John Wiley & Sons, Ltd.

First autochthonous malaria case due to Plasmodium vivax since eradication, Spain, October 2010.

PubMed

Santa-Olalla Peralta, P; Vazquez-Torres, M C; Latorre-Fandos, E; Mairal-Claver, P; Cortina-Solano, P; Puy-Azón, A; Adiego Sancho, B; Leitmeyer, K; Lucientes-Curdi, J; Sierra-Moros, M J

2010-10-14

In October 2010, one case of autochthonous malaria due to Plasmodium vivax was diagnosed in Spain. The case occurred in Aragon, north-eastern Spain, where the vector Anopheles atroparvus is present. Although the source of infection could not be identified, this event highlights that sporadic autochthonous transmission of vector-borne diseases in continental Europe is possible and calls for enhanced surveillance and vector control measures.

Eco-Bio-Social Determinants for House Infestation by Non-domiciliated Triatoma dimidiata in the Yucatan Peninsula, Mexico

PubMed Central

Dumonteil, Eric; Nouvellet, Pierre; Rosecrans, Kathryn; Ramirez-Sierra, Maria Jesus; Gamboa-León, Rubi; Cruz-Chan, Vladimir; Rosado-Vallado, Miguel; Gourbière, Sébastien

2013-01-01

Background Chagas disease is a vector-borne disease of major importance in the Americas. Disease prevention is mostly limited to vector control. Integrated interventions targeting ecological, biological and social determinants of vector-borne diseases are increasingly used for improved control. Methodology/principal findings We investigated key factors associated with transient house infestation by T. dimidiata in rural villages in Yucatan, Mexico, using a mixed modeling approach based on initial null-hypothesis testing followed by multimodel inference and averaging on data from 308 houses from three villages. We found that the presence of dogs, chickens and potential refuges, such as rock piles, in the peridomicile as well as the proximity of houses to vegetation at the periphery of the village and to public light sources are major risk factors for infestation. These factors explain most of the intra-village variations in infestation. Conclusions/significance These results underline a process of infestation distinct from that of domiciliated triatomines and may be used for risk stratification of houses for both vector surveillance and control. Combined integrated vector interventions, informed by an Ecohealth perspective, should aim at targeting several of these factors to effectively reduce infestation and provide sustainable vector control. PMID:24086790

Multi-stage Vector-Borne Zoonoses Models: A Global Analysis.

PubMed

Bichara, Derdei; Iggidr, Abderrahman; Smith, Laura

2018-04-25

A class of models that describes the interactions between multiple host species and an arthropod vector is formulated and its dynamics investigated. A host-vector disease model where the host's infection is structured into n stages is formulated and a complete global dynamics analysis is provided. The basic reproduction number acts as a sharp threshold, that is, the disease-free equilibrium is globally asymptotically stable (GAS) whenever [Formula: see text] and that a unique interior endemic equilibrium exists and is GAS if [Formula: see text]. We proceed to extend this model with m host species, capturing a class of zoonoses where the cross-species bridge is an arthropod vector. The basic reproduction number of the multi-host-vector, [Formula: see text], is derived and shown to be the sum of basic reproduction numbers of the model when each host is isolated with an arthropod vector. It is shown that the disease will persist in all hosts as long as it persists in one host. Moreover, the overall basic reproduction number increases with respect to the host and that bringing the basic reproduction number of each isolated host below unity in each host is not sufficient to eradicate the disease in all hosts. This is a type of "amplification effect," that is, for the considered vector-borne zoonoses, the increase in host diversity increases the basic reproduction number and therefore the disease burden.

Aedes-Borne Virus-Mosquito Interactions: Mass Spectrometry Strategies and Findings.

PubMed

Pando-Robles, Victoria; Batista, Cesar V

2017-06-01

Aedes-borne viruses are responsible for high-impact neglected tropical diseases and unpredictable outbreaks such as the ongoing Zika epidemics. Aedes mosquitoes spread different arboviruses such as Dengue virus (DENV), Chikungunya virus (CHIKV), and Zika virus, among others, and are responsible for the continuous emergence and reemergence of these pathogens. These viruses have complex transmission cycles that include two hosts, namely the Aedes mosquito as a vector and susceptible vertebrate hosts. Human infection with arboviruses causes diseases that range from subclinical or mild to febrile diseases, encephalitis, and hemorrhagic fever. Infected mosquitoes do not show detectable signs of disease, even though the virus maintains a lifelong persistent infection. The infection of the Aedes mosquito by viruses involves a molecular crosstalk between cell and viral proteins. An understanding of how mosquito vectors and viruses interact is of fundamental interest, and it also offers novel perspectives for disease control. In recent years, mass spectrometry (MS)-based strategies in combination with bioinformatics have been successfully applied to identify and quantify global changes in cellular proteins, lipids, peptides, and metabolites in response to viral infection. Although the information about proteomics in the Aedes mosquito is limited, the information that has been reported can set up the basis for future studies. This review reflects how MS-based approaches have extended our understanding of Aedes mosquito biology and the development of DENV and CHIKV infection in the vector. Finally, this review discusses future challenges in the field.

Evaluation of the Effect of Host Immune Status on Short-Term Yersinia pestis Infection in Fleas With Implications for the Enzootic Host Model for Maintenance of Y. pestis During Interepizootic Periods

PubMed Central

GRAHAM, CHRISTINE B.; WOODS, MICHAEL E.; VETTER, SARA M.; PETERSEN, JEANNINE M.; MONTENIERI, JOHN A.; HOLMES, JENNIFER L.; MAES, SARAH E.; BEARDEN, SCOTT W.; GAGE, KENNETH L.; EISEN, REBECCA J.

2015-01-01

Plague, a primarily flea-borne disease caused by Yersinia pestis, is characterized by rapidly spreading epizootics separated by periods of quiescence. Little is known about how and where Y. pestis persists between epizootics. It is commonly proposed, however, that Y. pestis is maintained during interepizootic periods in enzootic cycles involving flea vectors and relatively resistant host populations. According to this model, while susceptible individuals serve as infectious sources for feeding fleas and subsequently die of infection, resistant hosts survive infection, develop antibodies to the plague bacterium, and continue to provide bloodmeals to infected fleas. For Y. pestis to persist under this scenario, fleas must remain infected after feeding on hosts carrying antibodies to Y. pestis. Studies of other vector-borne pathogens suggest that host immunity may negatively impact pathogen survival in the vector. Here, we report infection rates and bacterial loads for fleas (both Xenopsylla cheopis (Rothschild) and Oropsylla montana (Baker)) that consumed an infectious bloodmeal and subsequently fed on an immunized or age-matched naive mouse. We demonstrate that neither the proportion of infected fleas nor the bacterial loads in infected fleas were significantly lower within 3 d of feeding on immunized versus naive mice. Our findings thus provide support for one assumption underlying the enzootic host model of interepizootic maintenance of Y. pestis. PMID:25276941

Anaplasma marginale actively modulates vacuolar maturation during intracellular infection of its tick vector dermacentor andersoni

USDA-ARS?s Scientific Manuscript database

Tick-borne transmission of bacterial pathogens in the Order Rickettsiales is responsible for a diversity of infectious diseases, many of them severe, in both humans and animals. Transmission dynamics differ among these pathogens and are reflected in the pathogen-vector interaction. Anaplasma margina...

Analysis of stage-specific protein expression during babesia bovis development within female rhipicephalus microplus

USDA-ARS?s Scientific Manuscript database

Arthropod borne pathogens have a complex life cycle that includes asexual reproduction of haploid stages in mammalian erythrocytes and development of diploid stages in the vector. Transition of Apicomplexan pathogens between the mammalian host and the arthropod vector is critical for ongoing transmi...

The influence of diet on the use of near-infrared spectroscopy to determine the age of female Aedes aegypti mosquitoes

USDA-ARS?s Scientific Manuscript database

Interventions targeting adult mosquitoes are used to combat transmission of vector-borne diseases, including dengue. Without available vaccines, targeting the primary vector, Aedes aegypti, is essential to prevent transmission. Older mosquitoes (>/='7 days) are of greatest epidemiological significan...

Controlling vector-borne disease and adapting to climate change with novel research on disease forecasting to target new vector control materials and technologies

USDA-ARS?s Scientific Manuscript database

Population growth, frontier agricultural expansion, and urbanization transform the landscape and the surrounding ecosystem, affecting climate and interactions between animals and humans, and significantly influencing the transmission dynamics and geographic distribution of malaria, dengue and other ...

Repellency and other biological effects of natural substances against the sand fly, Phlebotomus papatasi

USDA-ARS?s Scientific Manuscript database

Leishmaniasis is an insect-borne disease caused by several protozoan species in the genus Leishmania, vectored by sand fly species in the genera Phlebotomus, Lutzomyia or others, with different species affecting different geographic ranges. Phlebotomus papatasi (Scopoli) is a major vector of Leishma...

Workshop focuses on study of climate's effects on health

NASA Astrophysics Data System (ADS)

Diaz, Henry F.; Epstein, Paul R.; Aron, Joan L.; Confalonieri, Ulisses E. C.

Changes in temperature, precipitation, humidity, and storm patterns influence upsurges of waterborne diseases such as hepatitis, shigella dysentery, typhoid, and cholera as well as vector-borne pathogens such as malaria, dengue, yellow fever, encephalitis, schistosomiasis, plague, and hantavirus. Cycles of flooding and drought directly affect factors such as the multiplication rates of disease vectors, the biting rate of vectors, and the amount of host-vector interaction. Indirectly, climate influences parameters important to vector spread or survival such as agricultural practices, the disruption of ecosystems, or changes in social systems and practices, which in turn change the relationship between the parasite, the vector, its predators, and the host.

An analysis of community perceptions of mosquito-borne disease control and prevention in Sint Eustatius, Caribbean Netherlands

PubMed Central

Leslie, Teresa E.; Carson, Marianne; van Coeverden, Els; De Klein, Kirsten; Braks, Marieta; Krumeich, Anja

2017-01-01

ABSTRACT Background: In the Caribbean, mosquito-borne diseases are a public health threat. In Sint Eustatius, dengue, Chikungunya and Zika are now endemic. To control and prevent mosquito-borne diseases, the Sint Eustatius Public Health Department relies on the community to assist with the control of Aedes aegypti mosquito. Unfortunately, community based interventions are not always simple, as community perceptions and responses shape actions and influence behavioural responses Objective: The aim of this study was to determine how the Sint Eustatius population perceives the Aedes aegypti mosquito, mosquito-borne diseases and prevention and control measures and hypothesized that increased knowledge of the virus, vector, control and prevention should result in a lower AQ1 prevalence and incidence of mosquito-borne diseases. Methods: This study was conducted in Sint Eustatius island in the Eastern Caribbean. We combined qualitative and quantitative designs. We conducted interviews and focus groups discussions among community member and health professional in 2013 and 2015. We also conducted cross-sectional survey to assess local knowledge on the vector, virus, and control and prevention. Results: The population is knowledgeable; ©however, mosquito-borne diseases are not the highest health priority. While local knowledge is sometimes put into action, it happens on the 20 household/individual level as opposed to the community level. After the 2014 CHIK outbreak, there was an increase in knowledge about mosquito control and mosquito-borne diseases. Discussion: In the context of Sint Eustatius, when controlling the Aedes population it may be a strategic option to focus on the household level rather than the community and build collaborations with households by supporting them when they actively practice mosquito 25 control. To further increase the level of knowledge on the significance of mosquito-borne diseases, it may also be an option to contextualize the issue of the virus, vector, prevention and control into a broader context. Conclusion: As evidenced by the increasing number of mosquito-borne diseases on the island, it appears that knowledge amongst the lay community may not be transferred into 30 action. This may be attributed to the perception of the Sint Eustatius populations that mosquitoes and the viruses they carry are not a high priority in comparison to other health concerns. PMID:28766466

An analysis of community perceptions of mosquito-borne disease control and prevention in Sint Eustatius, Caribbean Netherlands.

PubMed

Leslie, Teresa E; Carson, Marianne; Coeverden, Els van; De Klein, Kirsten; Braks, Marieta; Krumeich, Anja

2017-01-01

In the Caribbean, mosquito-borne diseases are a public health threat. In Sint Eustatius, dengue, Chikungunya and Zika are now endemic. To control and prevent mosquito-borne diseases, the Sint Eustatius Public Health Department relies on the community to assist with the control of Aedes aegypti mosquito. Unfortunately, community based interventions are not always simple, as community perceptions and responses shape actions and influence behavioural responses Objective: The aim of this study was to determine how the Sint Eustatius population perceives the Aedes aegypti mosquito, mosquito-borne diseases and prevention and control measures and hypothesized that increased knowledge of the virus, vector, control and prevention should result in a lower AQ1 prevalence and incidence of mosquito-borne diseases. This study was conducted in Sint Eustatius island in the Eastern Caribbean. We combined qualitative and quantitative designs. We conducted interviews and focus groups discussions among community member and health professional in 2013 and 2015. We also conducted cross-sectional survey to assess local knowledge on the vector, virus, and control and prevention. The population is knowledgeable; ©however, mosquito-borne diseases are not the highest health priority. While local knowledge is sometimes put into action, it happens on the 20 household/individual level as opposed to the community level. After the 2014 CHIK outbreak, there was an increase in knowledge about mosquito control and mosquito-borne diseases. In the context of Sint Eustatius, when controlling the Aedes population it may be a strategic option to focus on the household level rather than the community and build collaborations with households by supporting them when they actively practice mosquito 25 control. To further increase the level of knowledge on the significance of mosquito-borne diseases, it may also be an option to contextualize the issue of the virus, vector, prevention and control into a broader context. As evidenced by the increasing number of mosquito-borne diseases on the island, it appears that knowledge amongst the lay community may not be transferred into 30 action. This may be attributed to the perception of the Sint Eustatius populations that mosquitoes and the viruses they carry are not a high priority in comparison to other health concerns.

Aedes aegypti (L.) in Latin American and Caribbean region: With growing evidence for vector adaptation to climate change?

PubMed

Chadee, Dave D; Martinez, Raymond

2016-04-01

Within Latin America and the Caribbean region the impact of climate change has been associated with the effects of rainfall and temperature on seasonal outbreaks of dengue but few studies have been conducted on the impacts of climate on the behaviour and ecology of Aedes aegypti mosquitoes.This study was conducted to examine the adaptive behaviours currently being employed by A. aegypti mosquitoes exposed to the force of climate change in LAC countries. The literature on the association between climate and dengue incidence is small and sometimes speculative. Few laboratory and field studies have identified research gaps. Laboratory and field experiments were designed and conducted to better understand the container preferences, climate-associated-adaptive behaviour, ecology and the effects of different temperatures and light regimens on the life history of A. aegypti mosquitoes. A. aegypti adaptive behaviours and changes in container preferences demonstrate how complex dengue transmission dynamics is, in different ecosystems. The use of underground drains and septic tanks represents a major behaviour change identified and compounds an already difficult task to control A. aegypti populations. A business as usual approach will exacerbate the problem and lead to more frequent outbreaks of dengue and chikungunya in LAC countries unless both area-wide and targeted vector control approaches are adopted. The current evidence and the results from proposed transdisciplinary research on dengue within different ecosystems will help guide the development of new vector control strategies and foster a better understanding of climate change impacts on vector-borne disease transmission. Copyright © 2016 Elsevier B.V. All rights reserved.

A Model Framework to Estimate Impact and Cost of Genetics-Based Sterile Insect Methods for Dengue Vector Control

PubMed Central

Alphey, Nina; Alphey, Luke; Bonsall, Michael B.

2011-01-01

Vector-borne diseases impose enormous health and economic burdens and additional methods to control vector populations are clearly needed. The Sterile Insect Technique (SIT) has been successful against agricultural pests, but is not in large-scale use for suppressing or eliminating mosquito populations. Genetic RIDL technology (Release of Insects carrying a Dominant Lethal) is a proposed modification that involves releasing insects that are homozygous for a repressible dominant lethal genetic construct rather than being sterilized by irradiation, and could potentially overcome some technical difficulties with the conventional SIT technology. Using the arboviral disease dengue as an example, we combine vector population dynamics and epidemiological models to explore the effect of a program of RIDL releases on disease transmission. We use these to derive a preliminary estimate of the potential cost-effectiveness of vector control by applying estimates of the costs of SIT. We predict that this genetic control strategy could eliminate dengue rapidly from a human community, and at lower expense (approximately US$ 2∼30 per case averted) than the direct and indirect costs of disease (mean US$ 86–190 per case of dengue). The theoretical framework has wider potential use; by appropriately adapting or replacing each component of the framework (entomological, epidemiological, vector control bio-economics and health economics), it could be applied to other vector-borne diseases or vector control strategies and extended to include other health interventions. PMID:21998654

Quantitative Differences in Salivary Pathogen Load during Tick Transmission Underlie Strain-Specific Variation in Transmission Efficiency of Anaplasma marginale

USDA-ARS?s Scientific Manuscript database

The relative fitness of arthropod-borne pathogens within the vector can be a major determinant of pathogen prevalence within the mammalian host population. Strains of the tick-borne rickettsia Anaplasma marginale differ markedly in transmission efficiency with consequent impact on pathogen strain st...

Novel flaviviruses from mosquitoes: mosquito-specific evolutionary lineages within the phylogenetic group of mosquito-borne flaviviruses.

PubMed

Huhtamo, Eili; Cook, Shelley; Moureau, Gregory; Uzcátegui, Nathalie Y; Sironen, Tarja; Kuivanen, Suvi; Putkuri, Niina; Kurkela, Satu; Harbach, Ralph E; Firth, Andrew E; Vapalahti, Olli; Gould, Ernest A; de Lamballerie, Xavier

2014-09-01

Novel flaviviruses that are genetically related to pathogenic mosquito-borne flaviviruses (MBFV) have been isolated from mosquitoes in various geographical locations, including Finland. We isolated and characterized another novel virus of this group from Finnish mosquitoes collected in 2007, designated as Ilomantsi virus (ILOV). Unlike the MBFV that infect both vertebrates and mosquitoes, the MBFV-related viruses appear to be specific to mosquitoes similar to the insect-specific flaviviruses (ISFs). In this overview of MBFV-related viruses we conclude that they differ from the ISFs genetically and antigenically. Phylogenetic analyses separated the MBFV-related viruses isolated in Africa, the Middle East and South America from those isolated in Europe and Asia. Serological cross-reactions of MBFV-related viruses with other flaviviruses and their potential for vector-borne transmission require further characterization. The divergent MBFV-related viruses are probably significantly under sampled to date and provide new information on the variety, properties and evolution of vector-borne flaviviruses. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Interplays between Soil-Borne Plant Viruses and RNA Silencing-Mediated Antiviral Defense in Roots

PubMed Central

Andika, Ida Bagus; Kondo, Hideki; Sun, Liying

2016-01-01

Although the majority of plant viruses are transmitted by arthropod vectors and invade the host plants through the aerial parts, there is a considerable number of plant viruses that infect roots via soil-inhabiting vectors such as plasmodiophorids, chytrids, and nematodes. These soil-borne viruses belong to diverse families, and many of them cause serious diseases in major crop plants. Thus, roots are important organs for the life cycle of many viruses. Compared to shoots, roots have a distinct metabolism and particular physiological characteristics due to the differences in development, cell composition, gene expression patterns, and surrounding environmental conditions. RNA silencing is an important innate defense mechanism to combat virus infection in plants, but the specific information on the activities and molecular mechanism of RNA silencing-mediated viral defense in root tissue is still limited. In this review, we summarize and discuss the current knowledge regarding RNA silencing aspects of the interactions between soil-borne viruses and host plants. Overall, research evidence suggests that soil-borne viruses have evolved to adapt to the distinct mechanism of antiviral RNA silencing in roots. PMID:27695446

Mapping of courses on vector biology and vector-borne diseases systems: time for a worldwide effort.

PubMed

Casas, Jérôme; Lazzari, Claudio; Insausti, Teresita; Launois, Pascal; Fouque, Florence

2016-11-01

Major emergency efforts are being mounted for each vector-borne disease epidemiological crisis anew, while knowledge about the biology of arthropods vectors is dwindling slowly but continuously, as is the number of field entomologists. The discrepancy between the rates of production of knowledge and its use and need for solving crises is widening, in particular due to the highly differing time spans of the two concurrent processes. A worldwide web based search using multiple key words and search engines of onsite and online courses in English, Spanish, Portuguese, French, Italian and German concerned with the biology of vectors identified over 140 courses. They are geographically and thematically scattered, the vast majority of them are on-site, with very few courses using the latest massive open online course (MOOC) powerfulness. Over two third of them is given in English and Western Africa is particularity poorly represented. The taxonomic groups covered are highly unbalanced towards mosquitoes. A worldwide unique portal to guide students of all grades and levels of expertise, in particular those in remote locations, is badly needed. This is the objective a new activity supported by the Special Programme for Research and Training in Tropical Diseases (TDR).

Mapping of courses on vector biology and vector-borne diseases systems: time for a worldwide effort

PubMed Central

Casas, Jérôme; Lazzari, Claudio; Insausti, Teresita; Launois, Pascal; Fouque, Florence

2016-01-01

Major emergency efforts are being mounted for each vector-borne disease epidemiological crisis anew, while knowledge about the biology of arthropods vectors is dwindling slowly but continuously, as is the number of field entomologists. The discrepancy between the rates of production of knowledge and its use and need for solving crises is widening, in particular due to the highly differing time spans of the two concurrent processes. A worldwide web based search using multiple key words and search engines of onsite and online courses in English, Spanish, Portuguese, French, Italian and German concerned with the biology of vectors identified over 140 courses. They are geographically and thematically scattered, the vast majority of them are on-site, with very few courses using the latest massive open online course (MOOC) powerfulness. Over two third of them is given in English and Western Africa is particularity poorly represented. The taxonomic groups covered are highly unbalanced towards mosquitoes. A worldwide unique portal to guide students of all grades and levels of expertise, in particular those in remote locations, is badly needed. This is the objective a new activity supported by the Special Programme for Research and Training in Tropical Diseases (TDR). PMID:27759770

Learning from Experience: The Public Health Response to West Nile Virus, SARS, Monkeypox, and Hepatitis A Outbreaks in the United States

DTIC Science & Technology

2005-01-01

chickens in May and June 2002, with the first human cases showing up in hospital emergency departments in July. The Louisiana outbreak lasted until... Mexico , that had been used in a salsa served in a Beaver County restaurant. A total of 660 cases were reported, resulting in 3 deaths. Table...imported from Africa Contaminated green onions imported from Mexico Transmission Vector-borne (mosquitoes) Respiratory droplets (person-to

Travel-associated and autochthonous Zika virus infection in mainland France, 1 January to 15 July 2016

PubMed Central

Septfons, A; Leparc-Goffart, I; Couturier, E; Franke, F; Deniau, J; Balestier, A; Guinard, A; Heuzé, G; Liebert, A H; Mailles, A; Ndong, JR; Poujol, I; Raguet, S; Rousseau, C; Saidouni-Oulebsir, A; Six, C; Subiros, M; Servas, V; Terrien, E; Tillaut, H; Viriot, D; Watrin, M; Wyndels, K; Noel, H; Paty, MC; De Valk, H

2016-01-01

During summer 2016, all the conditions for local mosquito-borne transmission of Zika virus (ZIKV) are met in mainland France: a competent vector, Aedes albopictus, a large number of travellers returning from ZIKV-affected areas, and an immunologically naive population. From 1 January to 15 July 2016, 625 persons with evidence of recent ZIKV infection were reported in mainland France. We describe the surveillance system in place and control measures implemented to reduce the risk of infection. PMID:27542120

Concurrent micro-RNA mediated silencing of tick-borne flavivirus replication in tick vector and in the brain of vertebrate host.

PubMed

Tsetsarkin, Konstantin A; Liu, Guangping; Kenney, Heather; Hermance, Meghan; Thangamani, Saravanan; Pletnev, Alexander G

2016-09-13

Tick-borne viruses include medically important zoonotic pathogens that can cause life-threatening diseases. Unlike mosquito-borne viruses, whose impact can be restrained via mosquito population control programs, for tick-borne viruses only vaccination remains the reliable means of disease prevention. For live vaccine viruses a concern exists, that spillovers from viremic vaccinees could result in introduction of genetically modified viruses into sustainable tick-vertebrate host transmission cycle in nature. To restrict tick-borne flavivirus (Langat virus, LGTV) vector tropism, we inserted target sequences for tick-specific microRNAs (mir-1, mir-275 and mir-279) individually or in combination into several distant regions of LGTV genome. This caused selective attenuation of viral replication in tick-derived cells. LGTV expressing combinations of target sequences for tick- and vertebrate CNS-specific miRNAs were developed. The resulting viruses replicated efficiently and remained stable in simian Vero cells, which do not express these miRNAs, however were severely restricted to replicate in tick-derived cells. In addition, simultaneous dual miRNA targeting led to silencing of virus replication in live Ixodes ricinus ticks and abolished virus neurotropism in highly permissive newborn mice. The concurrent restriction of adverse replication events in vertebrate and invertebrate hosts will, therefore, ensure the environmental safety of live tick-borne virus vaccine candidates.

Powassan Virus—A New Reemerging Tick-Borne Disease

PubMed Central

Fatmi, Syed Soheb; Zehra, Rija; Carpenter, David O.

2017-01-01

Powassan virus is a neurovirulent flavivirus consisting of two lineages causing meningoencephalitis. It is the only member of the tick-borne encephalitis serogroup which is present in mainland North America. With a total number of 27 cases from 1958 to 1998 and 98 cases from 1999 to 2016, reported cases have increased by 671% over the last 18 years. Powassan infection is transmitted by different tick species in different geographical regions. Ixodes scapularis is the primary vector that transmits the virus on the East Coast of US and Ixodes cookei in the Midwest and Canada, while Hemaphysalis longicornis is the vector in Russia. Powassan has no singular pathognomonic finding and presents with a wide spectrum of symptoms including severe neurological symptoms. The clinical challenge lies within the management of the disease as there is no standard diagnostic protocol and most cases are only diagnosed after a patient goes through an extensive workup for other infectious disease. The diagnosis is established by a combination of imaging and serologic tests. In case of Powassan meningoencephalitis, computed tomography scan and magnetic resonance imaging show vascular insults, which are also seen in cases of tick-borne encephalitis virus, another flavivirus of medical importance. Serologic tests are the gold standard for diagnosis, although testing is not widely available and only state health departments and Center for Disease Control and Prevention can perform Powassan-specific IgM antibody testing utilizing enzyme-linked immunosorbent assay and immunofluorescence antibody. Powassan is also of veterinary medical importance. Wildlife animals act as a reservoir to the pathogens, hence possessing threat to humans and domestic animals. This review highlights Powassan’s neurotropic presentation, epidemiology, diagnostic challenges, and prevalence. Strong emphasis is placed on establishing diagnostic protocols, widespread Powassan-specific IgM testing, role of the vector in disease presentation, and necessary preventive research. PMID:29312918

Reducing Tick-Borne Disease in Alabama: Linking Health Risk Perception with Spatial Analysis Using the NASA Earth Observing System

NASA Technical Reports Server (NTRS)

Hemmings, S.; Renneboog, N.; Firsing, S.; Capilouto, E.; Harden, J.; Hyden, R.; Tipre, M.; Zhang, Y.

2010-01-01

Lyme disease (LD) accounts for most vector-borne disease reports in the U.S., and although its existence in Alabama remains controversial, other tick-borne illnesses (TBI) such as Southern Tick-Associated Rash Illness (STARI) pose a health concern in the state. Phase One of the Marshall Space Flight Center-UAB DEVELOP study of TBI identified the presence of the chain of infection for LD (Ixodes scapularis ticks carrying Borrelia burgdorferi bacteria) and STARI (Amblyomma americanum ticks and an as-yet-unconfirmed agent) in Alabama. Both LD and STARI are associated with the development of erythema migrans rashes around an infected tick bite, and while treatable with oral antibiotics, a review of educational resources available to state residents revealed low levels of prevention information. To improve prevention, recognition, and treatment of TBI in Alabama, Phase Two builds a health communication campaign based on vector habitat mapping and risk perception assessment. NASA Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery identified likely tick habitats using remotely sensed measurements of vegetation vigor (Normalized Difference Vegetation Index) and soil moisture. Likely tick habitats, identified as those containing both high vegetation density and soil moisture, included Oak Mountain State Park, Bankhead National Forest, and Talladega National Forest. To target a high-risk group -- outdoor recreation program participants at Alabama universities -- the study developed a behavior survey instrument based on existing studies of LD risk factors and theoretical constructs from the Social Ecological Model and Health Belief Model. The survey instrument was amended to include geographic variables in the assessment of TBI knowledge, attitudes, and prevention behaviors, and the vector habitat model will be expanded to incorporate additional environmental variables and in situ data. Remotely sensed environmental data combined with risk perception assessments inform an ongoing outreach campaign consisting of stakeholder meetings and educational seminars.

Ontology for Vector Surveillance and Management

PubMed Central

LOZANO-FUENTES, SAUL; BANDYOPADHYAY, ARITRA; COWELL, LINDSAY G.; GOLDFAIN, ALBERT; EISEN, LARS

2013-01-01

Ontologies, which are made up by standardized and defined controlled vocabulary terms and their interrelationships, are comprehensive and readily searchable repositories for knowledge in a given domain. The Open Biomedical Ontologies (OBO) Foundry was initiated in 2001 with the aims of becoming an “umbrella” for life-science ontologies and promoting the use of ontology development best practices. A software application (OBO-Edit; *.obo file format) was developed to facilitate ontology development and editing. The OBO Foundry now comprises over 100 ontologies and candidate ontologies, including the NCBI organismal classification ontology (NCBITaxon), the Mosquito Insecticide Resistance Ontology (MIRO), the Infectious Disease Ontology (IDO), the IDOMAL malaria ontology, and ontologies for mosquito gross anatomy and tick gross anatomy. We previously developed a disease data management system for dengue and malaria control programs, which incorporated a set of information trees built upon ontological principles, including a “term tree” to promote the use of standardized terms. In the course of doing so, we realized that there were substantial gaps in existing ontologies with regards to concepts, processes, and, especially, physical entities (e.g., vector species, pathogen species, and vector surveillance and management equipment) in the domain of surveillance and management of vectors and vector-borne pathogens. We therefore produced an ontology for vector surveillance and management, focusing on arthropod vectors and vector-borne pathogens with relevance to humans or domestic animals, and with special emphasis on content to support operational activities through inclusion in databases, data management systems, or decision support systems. The Vector Surveillance and Management Ontology (VSMO) includes >2,200 unique terms, of which the vast majority (>80%) were newly generated during the development of this ontology. One core feature of the VSMO is the linkage, through the has_vector relation, of arthropod species to the pathogenic microorganisms for which they serve as biological vectors. We also recognized and addressed a potential roadblock for use of the VSMO by the vector-borne disease community: the difficulty in extracting information from OBO-Edit ontology files (*.obo files) and exporting the information to other file formats. A novel ontology explorer tool was developed to facilitate extraction and export of information from the VSMO *.obo file into lists of terms and their associated unique IDs in *.txt or *.csv file formats. These lists can then be imported into a database or data management system for use as select lists with predefined terms. This is an important step to ensure that the knowledge contained in our ontology can be put into practical use. PMID:23427646

Ontology for vector surveillance and management.

PubMed

Lozano-Fuentes, Saul; Bandyopadhyay, Aritra; Cowell, Lindsay G; Goldfain, Albert; Eisen, Lars

2013-01-01

Ontologies, which are made up by standardized and defined controlled vocabulary terms and their interrelationships, are comprehensive and readily searchable repositories for knowledge in a given domain. The Open Biomedical Ontologies (OBO) Foundry was initiated in 2001 with the aims of becoming an "umbrella" for life-science ontologies and promoting the use of ontology development best practices. A software application (OBO-Edit; *.obo file format) was developed to facilitate ontology development and editing. The OBO Foundry now comprises over 100 ontologies and candidate ontologies, including the NCBI organismal classification ontology (NCBITaxon), the Mosquito Insecticide Resistance Ontology (MIRO), the Infectious Disease Ontology (IDO), the IDOMAL malaria ontology, and ontologies for mosquito gross anatomy and tick gross anatomy. We previously developed a disease data management system for dengue and malaria control programs, which incorporated a set of information trees built upon ontological principles, including a "term tree" to promote the use of standardized terms. In the course of doing so, we realized that there were substantial gaps in existing ontologies with regards to concepts, processes, and, especially, physical entities (e.g., vector species, pathogen species, and vector surveillance and management equipment) in the domain of surveillance and management of vectors and vector-borne pathogens. We therefore produced an ontology for vector surveillance and management, focusing on arthropod vectors and vector-borne pathogens with relevance to humans or domestic animals, and with special emphasis on content to support operational activities through inclusion in databases, data management systems, or decision support systems. The Vector Surveillance and Management Ontology (VSMO) includes >2,200 unique terms, of which the vast majority (>80%) were newly generated during the development of this ontology. One core feature of the VSMO is the linkage, through the has vector relation, of arthropod species to the pathogenic microorganisms for which they serve as biological vectors. We also recognized and addressed a potential roadblock for use of the VSMO by the vector-borne disease community: the difficulty in extracting information from OBO-Edit ontology files (*.obo files) and exporting the information to other file formats. A novel ontology explorer tool was developed to facilitate extraction and export of information from the VSMO*.obo file into lists of terms and their associated unique IDs in *.txt or *.csv file formats. These lists can then be imported into a database or data management system for use as select lists with predefined terms. This is an important step to ensure that the knowledge contained in our ontology can be put into practical use.

Culicoides variipennis and bluetongue-virus epidemiology in the United States.

PubMed

Tabachnick, W J

1996-01-01

The bluetongue viruses are transmitted to ruminants in North America by Culicoides variipennis. US annual losses of approximately $125 million are due to restrictions on the movement of livestock and germplasm to bluetongue-free countries. Bluetongue is the most economically important arthropod-borne animal disease in the United States. Bluetongue is absent in the northeastern United States because of the inefficient vector ability there of C. variipennis for bluetongue. The vector of bluetongue virus elsewhere in the United States is C. variipennis sonorensis. The three C. variipennis subspecies differ in vector competence for bluetongue virus in the laboratory. Understanding C. variipennis genetic variation controlling bluetongue transmission will help identify geographic regions at risk for bluetongue and provide opportunities to prevent virus transmission. Information on C. variipennis and bluetongue epidemiology will improve trade and provide information to protect US livestock from domestic and foreign arthropod-borne pathogens.

Common themes in changing vector-borne disease scenarios.

PubMed

Molyneux, David H

2003-01-01

The impact of climate change on disease patterns is controversial. However, global burden of disease studies suggest that infectious diseases will contribute a proportionately smaller burden of disease over the next 2 decades as non-communicable diseases emerge as public health problems. However, infectious diseases contribute proportionately more in the poorest quintile of the population. Notwithstanding the different views of the impact of global warming on vector-borne infections this paper reviews the conditions which drive the changing epidemiology of these infections and suggests that such change is linked by common themes including interactions of generalist vectors and reservoir hosts at interfaces with humans, reduced biodiversity associated with anthropogenic environmental changes, increases in Plasmodium falciparum: P. vivax ratios and well-described land use changes such as hydrological, urbanization, agricultural, mining and forest-associated impacts (extractive activities, road building, deforestation and migration) which are seen on a global scale.

Prevalence of tick-borne pathogens in Ixodes ricinus and Dermacentor reticulatus ticks from different geographical locations in Belarus.

PubMed

Reye, Anna L; Stegniy, Valentina; Mishaeva, Nina P; Velhin, Sviataslau; Hübschen, Judith M; Ignatyev, George; Muller, Claude P

2013-01-01

Worldwide, ticks are important vectors of human and animal pathogens. Besides Lyme Borreliosis, a variety of other bacterial and protozoal tick-borne infections are of medical interest in Europe. In this study, 553 questing and feeding Ixodes ricinus (n = 327) and Dermacentor reticulatus ticks (n = 226) were analysed by PCR for Borrelia, Rickettsia, Anaplasma, Coxiella, Francisella and Babesia species. Overall, the pathogen prevalence in ticks was 30.6% for I. ricinus and 45.6% for D. reticulatus. The majority of infections were caused by members of the spotted-fever group rickettsiae (24.4%), 9.4% of ticks were positive for Borrelia burgdorferi sensu lato, with Borrelia afzelii being the most frequently detected species (40.4%). Pathogens with low prevalence rates in ticks were Anaplasma phagocytophilum (2.2%), Coxiella burnetii (0.9%), Francisella tularensis subspecies (0.7%), Bartonella henselae (0.7%), Babesia microti (0.5%) and Babesia venatorum (0.4%). On a regional level, hotspots of pathogens were identified for A. phagocytophilum (12.5-17.2%), F. tularensis ssp. (5.5%) and C. burnetii (9.1%), suggesting established zoonotic cycles of these pathogens at least at these sites. Our survey revealed a high burden of tick-borne pathogens in questing and feeding I. ricinus and D. reticulatus ticks collected in different regions in Belarus, indicating a potential risk for humans and animals. Identified hotspots of infected ticks should be included in future surveillance studies, especially when F. tularensis ssp. and C. burnetii are involved.

Management of arthropod pathogen vectors in North America: Minimizing adverse effects on pollinators

USGS Publications Warehouse

Ginsberg, Howard; Bargar, Timothy A.; Hladik, Michelle L.; Lubelczyk, Charles

2017-01-01

Tick and mosquito management is important to public health protection. At the same time, growing concerns about declines of pollinator species raise the question of whether vector control practices might affect pollinator populations. We report the results of a task force of the North American Pollinator Protection Campaign (NAPPC) that examined potential effects of vector management practices on pollinators, and how these programs could be adjusted to minimize negative effects on pollinating species. The main types of vector control practices that might affect pollinators are landscape manipulation, biocontrol, and pesticide applications. Some current practices already minimize effects of vector control on pollinators (e.g., short-lived pesticides and application-targeting technologies). Nontarget effects can be further diminished by taking pollinator protection into account in the planning stages of vector management programs. Effects of vector control on pollinator species often depend on specific local conditions (e.g., proximity of locations with abundant vectors to concentrations of floral resources), so planning is most effective when it includes collaborations of local vector management professionals with local experts on pollinators. Interventions can then be designed to avoid pollinators (e.g., targeting applications to avoid blooming times and pollinator nesting habitats), while still optimizing public health protection. Research on efficient targeting of interventions, and on effects on pollinators of emerging technologies, will help mitigate potential deleterious effects on pollinators in future management programs. In particular, models that can predict effects of integrated pest management on vector-borne pathogen transmission, along with effects on pollinator populations, would be useful for collaborative decision-making.

An age-structured extension to the vectorial capacity model.

PubMed

Novoseltsev, Vasiliy N; Michalski, Anatoli I; Novoseltseva, Janna A; Yashin, Anatoliy I; Carey, James R; Ellis, Alicia M

2012-01-01

Vectorial capacity and the basic reproductive number (R(0)) have been instrumental in structuring thinking about vector-borne pathogen transmission and how best to prevent the diseases they cause. One of the more important simplifying assumptions of these models is age-independent vector mortality. A growing body of evidence indicates that insect vectors exhibit age-dependent mortality, which can have strong and varied affects on pathogen transmission dynamics and strategies for disease prevention. Based on survival analysis we derived new equations for vectorial capacity and R(0) that are valid for any pattern of age-dependent (or age-independent) vector mortality and explore the behavior of the models across various mortality patterns. The framework we present (1) lays the groundwork for an extension and refinement of the vectorial capacity paradigm by introducing an age-structured extension to the model, (2) encourages further research on the actuarial dynamics of vectors in particular and the relationship of vector mortality to pathogen transmission in general, and (3) provides a detailed quantitative basis for understanding the relative impact of reductions in vector longevity compared to other vector-borne disease prevention strategies. Accounting for age-dependent vector mortality in estimates of vectorial capacity and R(0) was most important when (1) vector densities are relatively low and the pattern of mortality can determine whether pathogen transmission will persist; i.e., determines whether R(0) is above or below 1, (2) vector population growth rate is relatively low and there are complex interactions between birth and death that differ fundamentally from birth-death relationships with age-independent mortality, and (3) the vector exhibits complex patterns of age-dependent mortality and R(0) ∼ 1. A limiting factor in the construction and evaluation of new age-dependent mortality models is the paucity of data characterizing vector mortality patterns, particularly for free ranging vectors in the field.

An Age-Structured Extension to the Vectorial Capacity Model

PubMed Central

Novoseltsev, Vasiliy N.; Michalski, Anatoli I.; Novoseltseva, Janna A.; Yashin, Anatoliy I.; Carey, James R.; Ellis, Alicia M.

2012-01-01

Background Vectorial capacity and the basic reproductive number (R0) have been instrumental in structuring thinking about vector-borne pathogen transmission and how best to prevent the diseases they cause. One of the more important simplifying assumptions of these models is age-independent vector mortality. A growing body of evidence indicates that insect vectors exhibit age-dependent mortality, which can have strong and varied affects on pathogen transmission dynamics and strategies for disease prevention. Methodology/Principal Findings Based on survival analysis we derived new equations for vectorial capacity and R0 that are valid for any pattern of age-dependent (or age–independent) vector mortality and explore the behavior of the models across various mortality patterns. The framework we present (1) lays the groundwork for an extension and refinement of the vectorial capacity paradigm by introducing an age-structured extension to the model, (2) encourages further research on the actuarial dynamics of vectors in particular and the relationship of vector mortality to pathogen transmission in general, and (3) provides a detailed quantitative basis for understanding the relative impact of reductions in vector longevity compared to other vector-borne disease prevention strategies. Conclusions/Significance Accounting for age-dependent vector mortality in estimates of vectorial capacity and R0 was most important when (1) vector densities are relatively low and the pattern of mortality can determine whether pathogen transmission will persist; i.e., determines whether R0 is above or below 1, (2) vector population growth rate is relatively low and there are complex interactions between birth and death that differ fundamentally from birth-death relationships with age-independent mortality, and (3) the vector exhibits complex patterns of age-dependent mortality and R0∼1. A limiting factor in the construction and evaluation of new age-dependent mortality models is the paucity of data characterizing vector mortality patterns, particularly for free ranging vectors in the field. PMID:22724022

Ticks and Tick-Borne Infections: Complex Ecology, Agents, and Host Interactions.

PubMed

Wikel, Stephen K

2018-06-20

Ticks transmit the most diverse array of infectious agents of any arthropod vector. Both ticks and the microbes they transmit are recognized as significant threats to human and veterinary public health. This article examines the potential impacts of climate change on the distribution of ticks and the infections they transmit; the emergence of novel tick-borne pathogens, increasing geographic range and incidence of tick-borne infections; and advances in the characterization of tick saliva mediated modulation of host defenses and the implications of those interactions for transmission, establishment, and control of tick infestation and tick-borne infectious agents.

Interannual variability of human plague occurrence in the Western United States explained by tropical and North Pacific Ocean climate variability.

PubMed

Ari, Tamara Ben; Gershunov, Alexander; Tristan, Rouyer; Cazelles, Bernard; Gage, Kenneth; Stenseth, Nils C

2010-09-01

Plague is a vector-borne, highly virulent zoonotic disease caused by the bacterium Yersinia pestis. It persists in nature through transmission between its hosts (wild rodents) and vectors (fleas). During epizootics, the disease expands and spills over to other host species such as humans living in or close to affected areas. Here, we investigate the effect of large-scale climate variability on the dynamics of human plague in the western United States using a 56-year time series of plague reports (1950-2005). We found that El Niño Southern Oscillation and Pacific Decadal Oscillation in combination affect the dynamics of human plague over the western United States. The underlying mechanism could involve changes in precipitation and temperatures that impact both hosts and vectors. It is suggested that snow also may play a key role, possibly through its effects on summer soil moisture, which is known to be instrumental for flea survival and development and sustained growth of vegetation for rodents.

Dengue and Zika viruses: lessons learned from the similarities between these Aedes mosquito-vectored arboviruses.

PubMed

Suwanmanee, San; Luplertlop, Natthanej

2017-02-01

The currently spreading arbovirus epidemic is having a severe impact on human health worldwide. The two most common flaviviruses, dengue virus (DENV) and Zika virus (ZIKV), are transmitted through the same viral vector, Aedes spp. mosquitoes. Since the discovery of DENV in 1943, this virus has been reported to cause around 390 million human infections per year, approximately 500,000 of which require hospitalization and over 20,000 of which are lethal. The present DENV epidemic is primarily concentrated in Southeast Asia. ZIKV, which was discovered in 1952, is another important arthropod-borne flavivirus. The neurotropic role of ZIKV has been reported in infected newborns with microcephaly and in adults with Guillain-Barre syndrome. Despite DENV and ZIKV sharing the same viral vector, their complex pathogenic natures are poorly understood, and the infections they cause do not have specific treatments or effective vaccines. Therefore, this review will describe what is currently known about the clinical characteristics, pathogenesis mechanisms, and transmission of these two viruses. Better understanding of the interrelationships between DENV and ZIKV will provide a useful perspective for developing an effective strategy for controlling both viruses in the future.

Taiwan's Travel and Border Health Measures in Response to Zika.

PubMed

Ho, Li-Li; Tsai, Yu-Hui; Lee, Wang-Ping; Liao, Szu-Tsai; Wu, Li-Gin; Wu, Yi-Chun

Zika virus has recently emerged as a worldwide public health concern. Travel and border health measures stand as one of the main strategies and frontline defenses in responding to international epidemics. As of October 31, 2016, Taiwan has reported 13 imported cases, 5 of which were detected through routine entry screening and active monitoring at international airports. This article shares Taiwan's disease surveillance activities at designated points of entry and travel and border health measures in response to Zika. The Taiwan government collaborates with its tourism industry to disseminate information about precautionary measures and encourages tour guides to report suspected individuals or events to activate early response measures. Taiwan also engages in vector control activities at points of entry, including targeting aircraft from countries where vector-borne diseases are endemic, implementing mosquito sweep measures, and collecting vector surveillance data. In future emerging and reemerging disease events, entry surveillance at designated points of entry may enable early detection of diseases of international origin and more rapid activation of public health preparedness activities and international collaboration. Taiwan will continue to maximize border and travel health measures in compliance with IHR (2005) requirements, which rely on continued risk assessment, practical implementation activities, and engagement with all stakeholders.

On the use of RADARSAT-1 for monitoring malaria risk in Kenya

NASA Astrophysics Data System (ADS)

Ross, S. G.; Thomson, M. C.; Pultz, T.; Mbogo, C. M.; Regens, J. L.; Swalm, C.; Githure, J.; Yan, G.; Gu, W.; Beier, J. C.

2002-01-01

The incidence and spread of vector-borne infectious diseases are increasing concerns in many parts of the world. Earth obervation techniques provide a recognised means for monitoring and mapping disease risk as well as correlating environmental indicators with various disease vectors. Because the areas most impacted by vector-borne disease are remote and not easily monitored using traditional, labor intensive survey techniques, high spatial and temporal coverage provided by spaceborne sensors allows for the investigation of large areas in a timely manner. However, since the majority of infectious diseases occur in tropical areas, one of the main barriers to earth observation techniques is persistent cloud-cover. Synthetic Aperture Radar (SAR) technology offers a solution to this problem by providing all-weather, day and night imaging capability. Based on SAR's sensitivity to target moisture conditions, sensors such as RADARSAT-1 can be readily used to map wetland and swampy areas that are conducive to functioning as aquatic larval habitats. Irrigation patterns, deforestation practises and the effects of local flooding can be monitored using SAR imagery, and related to potential disease vector abundance and proximity to populated areas. This paper discusses the contribution of C-band radar remote sensing technology to monitoring and mapping malaria. Preliminary results using RADARSAT-1 for identifying areas of high mosquito (Anopheles gambiae s.l.) abundance along the Kenya coast will be discussed. The authors consider the potential of RADARSAT-1 data based on SAR sensor characteristics and the preliminary results obtained. Further potential of spaceborne SAR data for monitoring vector-borne disease is discussed with respect to future advanced SAR sensors such as RADARSAT-2.

First record of the invasive mosquito species Aedes (Stegomyia) albopictus (Diptera: Culicidae) on the southernmost Mediterranean islands of Italy and Europe.

PubMed

Di Luca, Marco; Toma, Luciano; Severini, Francesco; Boccolini, Daniela; D'Avola, Salvatore; Todaro, Diego; Stancanelli, Alessandra; Antoci, Francesco; La Russa, Francesco; Casano, Sandro; Sotera, Salvatore D; Carraffa, Eugenio; Versteirt, Veerle; Schaffner, Francis; Romi, Roberto; Torina, Alessandra

2017-11-02

Aedes albopictus, a known worldwide vector of several mosquito-borne disease pathogens including dengue, chikungunya and Zika viruses, was introduced into Europe in the late 1970s through global trade. First recorded in northern Italy in 1990, this mosquito species has rapidly spread throughout the country, where it was responsible for an outbreak of chikungunya in 2007 that affected more than 200 people. As part of the VectorNet project, which is aimed at improving preparedness and responsiveness for animal and human vector-borne diseases in Europe, a mosquito targeted study was carried out on the three southernmost Italian islands. The objective was to verify the current European southern distribution limits of Ae. albopictus and the potential occurrence of other invasive mosquito species, in the light of the introduction of high risk for vector-borne disease pathogens into Europe via migration flows. In the summer 2015, six surveys for container-breeding mosquitoes were carried out by setting up a network of oviposition traps and BG Sentinel traps in selected areas on the islands of Pantelleria, Lampedusa and Linosa. Aedes albopictus was found on all three islands under investigation. The consequences on public health with regard to the presence of this mosquito vector and the migrant people entering the country from Africa and the Middle East are also discussed here. The detection of the Asian tiger mosquito on these islands, which represent the last European strip of land facing Africa, has important implications for public health policy and should prompt the national authorities to implement tailored surveillance activities and reinforce plans for preparedness strategies in such contexts.

Genetic variation in transmission success of the Lyme borreliosis pathogen Borrelia afzelii.

PubMed

Tonetti, Nicolas; Voordouw, Maarten J; Durand, Jonas; Monnier, Séverine; Gern, Lise

2015-04-01

The vector-to-host and host-to-vector transmission steps are the two critical events that define the life cycle of any vector-borne pathogen. We expect negative genetic correlations between these two transmission phenotypes, if parasite genotypes specialized at invading the vector are less effective at infecting the vertebrate host and vice versa. We used the tick-borne bacterium Borrelia afzelii, a causative agent of Lyme borreliosis in Europe, to test whether genetic trade-offs exist between tick-to-host, systemic (host-to-tick), and a third mode of co-feeding (tick-to-tick) transmission. We worked with six strains of B. afzelii that were differentiated according to their ospC gene. We compared the three components of transmission among the B. afzelii strains using laboratory rodents as the vertebrate host and a laboratory colony of Ixodes ricinus as the tick vector. We used next generation matrix models to combine these transmission components into a single estimate of the reproductive number (R0) for each B. afzelii strain. We also tested whether these strain-specific estimates of R0 were correlated with the strain-specific frequencies in the field. We found significant genetic variation in the three transmission components among the B. afzelii strains. This is the first study to document genetic variation in co-feeding transmission for any tick-borne pathogen. We found no evidence of trade-offs as the three pairwise correlations of the transmission rates were all positive. The R0 values from our laboratory study explained 45% of the variation in the frequencies of the B. afzelii ospC strains in the field. Our study suggests that laboratory estimates of pathogen fitness can predict the distribution of pathogen strains in nature. Copyright © 2015 Elsevier GmbH. All rights reserved.

Epidemiological surveillance methods for vector-borne diseases.

PubMed

Thompson, P N; Etter, E

2015-04-01

Compared with many other diseases, the ever-increasing threat of vector-borne diseases (VBDs) represents a great challenge to public and animal health managers. Complex life cycles, changing distribution ranges, a variety of potential vectors and hosts, and the possible role of reservoirs make surveillance for VBDs a grave concern in a changing environment with increasing economic constraints. Surveillance activities may have various specific objectives and may focus on clinical disease, pathogens, vectors, hosts and/or reservoirs, but ultimately such activities should improve our ability to predict, prevent and/or control the diseases concerned. This paper briefly reviews existing and newly developed tools for the surveillance of VBDs. A range of examples, by no means exhaustive, illustrates that VBD surveillance usually involves a combination of methods to achieve its aims, and is best accomplished when these techniques are adapted to the specific environment and constraints of the region. More so than any other diseases, VBDs respect no administrative boundaries; in addition, animal, human and commodity movements are increasing dramatically, with illegal or unknown movements difficult to quantify. Vector-borne disease surveillance therefore becomes a serious issue for local and national organisations and is being conducted more and more at the regional and international level through multidisciplinary networks. With economic and logistical constraints, tools for optimising and evaluating the performance of surveillance systems are essential and examples of recent developments in this area are included. The continuous development of mapping, analytical and modelling tools provides us with an enhanced ability to interpret, visualise and communicate surveillance results. This review also demonstrates the importance of the link between surveillance and research, with interactions and benefits in both directions.

Towards a resource-based habitat approach for spatial modelling of vector-borne disease risks.

PubMed

Hartemink, Nienke; Vanwambeke, Sophie O; Purse, Bethan V; Gilbert, Marius; Van Dyck, Hans

2015-11-01

Given the veterinary and public health impact of vector-borne diseases, there is a clear need to assess the suitability of landscapes for the emergence and spread of these diseases. Current approaches for predicting disease risks neglect key features of the landscape as components of the functional habitat of vectors or hosts, and hence of the pathogen. Empirical-statistical methods do not explicitly incorporate biological mechanisms, whereas current mechanistic models are rarely spatially explicit; both methods ignore the way animals use the landscape (i.e. movement ecology). We argue that applying a functional concept for habitat, i.e. the resource-based habitat concept (RBHC), can solve these issues. The RBHC offers a framework to identify systematically the different ecological resources that are necessary for the completion of the transmission cycle and to relate these resources to (combinations of) landscape features and other environmental factors. The potential of the RBHC as a framework for identifying suitable habitats for vector-borne pathogens is explored and illustrated with the case of bluetongue virus, a midge-transmitted virus affecting ruminants. The concept facilitates the study of functional habitats of the interacting species (vectors as well as hosts) and provides new insight into spatial and temporal variation in transmission opportunities and exposure that ultimately determine disease risks. It may help to identify knowledge gaps and control options arising from changes in the spatial configuration of key resources across the landscape. The RBHC framework may act as a bridge between existing mechanistic and statistical modelling approaches. © 2014 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.

Avian species diversity and transmission of West Nile virus in Atlanta, Georgia.

PubMed

Levine, Rebecca S; Hedeen, David L; Hedeen, Meghan W; Hamer, Gabriel L; Mead, Daniel G; Kitron, Uriel D

2017-02-03

The dilution effect is the reduction in vector-borne pathogen transmission associated with the presence of diverse potential host species, some of which are incompetent. It is popularized as the notion that increased biodiversity leads to decreased rates of disease. West Nile virus (WNV) is an endemic mosquito-borne virus in the United States that is maintained in a zoonotic cycle involving various avian host species. In Atlanta, Georgia, substantial WNV presence in the vector and host species has not translated into a high number of human cases. To determine whether a dilution effect was contributing to this reduced transmission, we characterized the host species community composition and performed WNV surveillance of hosts and vectors in urban Atlanta between 2010 and 2011. We tested the relationship between host diversity and both host seroprevalence and vector infection rates using a negative binomial generalized linear mixed model. Regardless of how we measured host diversity or whether we considered host seroprevalence and vector infection rates as predictor variables or outcome variables, we did not detect a dilution effect. Rather, we detected an amplification effect, in which increased host diversity resulted in increased seroprevalence or infection rates; this is the first empirical evidence for this effect in a mosquito-borne system. We suggest that this effect may be driven by an over-abundance of moderately- to poorly-competent host species, such as northern cardinals and members of the Mimid family, which cause optimal hosts to become rarer and present primarily in species-rich areas. Our results support the notion that dilution or amplification effects depend more on the identities of the species comprising the host community than on the absolute diversity of hosts.

Climate change, zoonoses and India.

PubMed

Singh, B B; Sharma, R; Gill, J P S; Aulakh, R S; Banga, H S

2011-12-01

Economic trends have shaped our growth and the growth of the livestock sector, but atthe expense of altering natural resources and systems in ways that are not always obvious. Now, however, the reverse is beginning to happen, i.e. environmental trends are beginning to shape our economy and health status. In addition to water, air and food, animals and birds play a pivotal role in the maintenance and transmission of important zoonotic diseases in nature. It is generally considered that the prevalence of vector-borne and waterborne zoonoses is likely to increase in the coming years due to the effects of global warming in India. In recent years, vector-borne diseases have emerged as a serious public health problem in countries of the South-East Asia region, including India. Vector-borne zoonoses now occur in epidemic form almost on an annual basis, causing considerable morbidity and mortality. New reservoir areas of cutaneous leishmaniosis in South India have been recognised, and the role of climate change in its re-emergence warrants further research, as does the role of climate change in the ascendancy of waterborne and foodborne illness. Similarly, climate change that leads to warmer and more humid conditions may increase the risk of transmission of airborne zoonoses, and hot and drier conditions may lead to a decline in the incidence of disease(s). The prevalence of these zoonotic diseases and their vectors and the effect of climate change on important zoonoses in India are discussed in this review.

Quantification of vector and host competence for Japanese encephalitis virus: a systematic review of the literature

USDA-ARS?s Scientific Manuscript database

Japanese encephalitis virus (JEV) is a virus of the Flavivirus genus that may result in encephalitis in human hosts. This vector-borne zoonosis occurs in Eastern and Southeastern Asia and an intentional or inadvertent introduction into the United States (US) will have major public health and economi...

Assessing the impact of climate change on vector-borne viruses in the EU through the elicitation of expert opinion.

PubMed

Gale, P; Brouwer, A; Ramnial, V; Kelly, L; Kosmider, R; Fooks, A R; Snary, E L

2010-02-01

Expert opinion was elicited to undertake a qualitative risk assessment to estimate the current and future risks to the European Union (EU) from five vector-borne viruses listed by the World Organization for Animal Health. It was predicted that climate change will increase the risk of incursions of African horse sickness virus (AHSV), Crimean-Congo haemorrhagic fever virus (CCHFV) and Rift Valley fever virus (RVFV) into the EU from other parts of the world, with African swine fever virus (ASFV) and West Nile virus (WNV) being less affected. Currently the predicted risks of incursion were lowest for RVFV and highest for ASFV. Risks of incursion were considered for six routes of entry (namely vectors, livestock, meat products, wildlife, pets and people). Climate change was predicted to increase the risk of incursion from entry of vectors for all five viruses to some degree, the strongest effects being predicted for AHSV, CCHFV and WNV. This work will facilitate identification of appropriate risk management options in relation to adaptations to climate change.

Land use change and human health

NASA Astrophysics Data System (ADS)

Patz, Jonathan A.; Norris, Douglas E.

Disease emergence events have been documented following several types of land use change. This chapter reviews several health-relevant land use changes recognized today, including: 1) urbanization and urban sprawl; 2) water projects and agricultural development; 3) road construction and deforestation in the tropics; and 4) regeneration of temperate forests. Because habitat or climatic change substantially affects intermediate invertebrate hosts involved in many prevalent diseases, this chapter provides a basic description of vector-borne disease biology as a foundation for analyzing the effects of land use change. Urban sprawl poses health challenges stemming from heat waves exacerbated by the "urban heat island" effect, as well as from water contamination due to expanses of impervious road and concrete surfaces. Dams, irrigation and agricultural development have long been associated with diseases such as schistosomiasis and filariasis. Better management methods are required to address the trade-offs between expanded food production and altered habitats promoting deadly diseases. Deforestation can increase the nature and number of breeding sites for vector-borne diseases, such as malaria and onchocerciasis. Human host and disease vector interaction further increases risk, as can a change in arthropod-vector species composition.

The Fleas (Siphonaptera) in Iran: Diversity, Host Range, and Medical Importance

PubMed Central

Maleki-Ravasan, Naseh; Solhjouy-Fard, Samaneh; Beaucournu, Jean-Claude; Laudisoit, Anne

2017-01-01

Background Flea-borne diseases have a wide distribution in the world. Studies on the identity, abundance, distribution and seasonality of the potential vectors of pathogenic agents (e.g. Yersinia pestis, Francisella tularensis, and Rickettsia felis) are necessary tools for controlling and preventing such diseases outbreaks. The improvements of diagnostic tools are partly responsible for an easier detection of otherwise unnoticed agents in the ectoparasitic fauna and as such a good taxonomical knowledge of the potential vectors is crucial. The aims of this study were to make an exhaustive inventory of the literature on the fleas (Siphonaptera) and range of associated hosts in Iran, present their known distribution, and discuss their medical importance. Methodology/Principal Findings The data were obtained by an extensive literature review related to medically significant fleas in Iran published before 31st August 2016. The flea-host specificity was then determined using a family and subfamily-oriented criteria to further realize and quantify the shared and exclusive vertebrate hosts of fleas among Iran fleas. The locations sampled and reported in the literature were primarily from human habitation, livestock farms, poultry, and rodents’ burrows of the 31 provinces of the country. The flea fauna were dominated by seven families, namely the Ceratophyllidae, Leptopsyllidae, Pulicidae, Ctenophthalmidae, Coptopsyllidae, Ischnopsyllidae and Vermipsyllidae. The hosts associated with Iran fleas ranged from the small and large mammals to the birds. Pulicidae were associated with 73% (56/77) of identified host species. Flea-host association analysis indicates that rodents are the common hosts of 5 flea families but some sampling bias results in the reduced number of bird host sampled. Analyses of flea-host relationships at the subfamily level showed that most vertebrates hosted fleas belgonging to 3 subfamilies namely Xenopsyllinae (n = 43), Ctenophthalminae (n = 20) and Amphipsyllinae (n = 17). Meriones persicus was infested by 11 flea subfamilies in the arid, rocky, mountainous regions and Xenopsyllinae were hosted by at least 43 mammal species. These findings place the Persian jird (M. persicus) and the Xenopsyllinae as the major vertebrate and vector hosts of flea-borne diseases in Iran including Yersinia pestis, the etiological agent of plague. We found records of at least seven vector-borne pathogenic agents that can potentially be transmitted by the 117 flea species (or subspecies) of Iran. Conclusions/Significance Herein, we performed a thorough inventary of the flea species and their associated hosts, their medical importance and geographic distribution throughout Iran. This exercise allowed assessing the diversity of flea species with the potential flea-borne agents transmission risk in the country by arranging published data on flea-host associations. This information is a first step for issuing public health policies and rodent-flea control campaigns in Iran as well as those interested in the ecology/epidemiology of flea-borne disease. PMID:28068343

All That Glisters Is Not Gold: Sampling-Process Uncertainty in Disease-Vector Surveys with False-Negative and False-Positive Detections

PubMed Central

Abad-Franch, Fernando; Valença-Barbosa, Carolina; Sarquis, Otília; Lima, Marli M.

2014-01-01

Background Vector-borne diseases are major public health concerns worldwide. For many of them, vector control is still key to primary prevention, with control actions planned and evaluated using vector occurrence records. Yet vectors can be difficult to detect, and vector occurrence indices will be biased whenever spurious detection/non-detection records arise during surveys. Here, we investigate the process of Chagas disease vector detection, assessing the performance of the surveillance method used in most control programs – active triatomine-bug searches by trained health agents. Methodology/Principal Findings Control agents conducted triplicate vector searches in 414 man-made ecotopes of two rural localities. Ecotope-specific ‘detection histories’ (vectors or their traces detected or not in each individual search) were analyzed using ordinary methods that disregard detection failures and multiple detection-state site-occupancy models that accommodate false-negative and false-positive detections. Mean (±SE) vector-search sensitivity was ∼0.283±0.057. Vector-detection odds increased as bug colonies grew denser, and were lower in houses than in most peridomestic structures, particularly woodpiles. False-positive detections (non-vector fecal streaks misidentified as signs of vector presence) occurred with probability ∼0.011±0.008. The model-averaged estimate of infestation (44.5±6.4%) was ∼2.4–3.9 times higher than naïve indices computed assuming perfect detection after single vector searches (11.4–18.8%); about 106–137 infestation foci went undetected during such standard searches. Conclusions/Significance We illustrate a relatively straightforward approach to addressing vector detection uncertainty under realistic field survey conditions. Standard vector searches had low sensitivity except in certain singular circumstances. Our findings suggest that many infestation foci may go undetected during routine surveys, especially when vector density is low. Undetected foci can cause control failures and induce bias in entomological indices; this may confound disease risk assessment and mislead program managers into flawed decision making. By helping correct bias in naïve indices, the approach we illustrate has potential to critically strengthen vector-borne disease control-surveillance systems. PMID:25233352

Pilot longitudinal mosquito surveillance study in the Danube Delta Biosphere Reserve and the first reports of Anopheles algeriensis Theobald, 1903 and Aedes hungaricus Mihályi, 1955 for Romania.

PubMed

Török, Edina; Tomazatos, Alexandru; Cadar, Daniel; Horváth, Cintia; Keresztes, Lujza; Jansen, Stephanie; Becker, Norbert; Kaiser, Achim; Popescu, Octavian; Schmidt-Chanasit, Jonas; Jöst, Hanna; Lühken, Renke

2016-04-11

Mosquito-borne viruses (moboviruses) are of growing importance in many countries of Europe. In Romania and especially in the Danube Delta Biosphere Reserve (DDBR), mosquito and mobovirus surveillance are not performed on a regular basis. However, this type of study is crucially needed to evaluate the risk of pathogen transmission, to understand the ecology of emerging moboviruses, or to plan vector control programmes. We initiated a longitudinal mosquito surveillance study with carbon dioxide-baited Heavy Duty Encephalitis Vector Survey traps at four sampling sites to analyse the spatio-temporal pattern of the (i) mosquito species composition and diversity, (ii) functional groups of mosquitoes (oviposition sites, overwintering stage, and number of generations), and (iii) the occurrence of potential West Nile virus (WNV) vectors. During 2014, a total of 240,546 female mosquitoes were collected. All species were identified using morphological characteristics and further confirmed by mitochondrial cytochrome c oxidase subunit I (COI) gene analysis of selected specimens. The two most common taxa were Coquilettidia richiardii (40.9 %) and Anopheles hyrcanus (34.1 %), followed by Culex pipiens (sensu lato) (s.l.)/Cx. torrentium (7.7 %), Aedes caspius (5.7 %), Cx. modestus (4.0 %), An. maculipennis (s.l.) (3.9 %), and Ae. vexans (3.0 %). A further seven species were less common in the area studied, including two new records for Romania: An. algeriensis and Ae. hungaricus. Phylogenetic analysis of COI gene demonstrated the evolutionary relatedness of most species with specimens of the same species collected in other European regions, except Ae. detritus and An. algeriensis, which exhibited high genetic diversity. Due to the dominance of Cq. richiardii and An. hyrcanus (75 % of all collected specimens), the overall phenology and temporal pattern of functional groups basically followed the phenology of both species. A huge proportion of the mosquito population in the course of the entire sampling period can be classified as potential WNV vectors. With 40 % of all collected specimens, the most frequent species Cq. richiardii is probably the most important vector of WNV in the DDBR. This is the first DNA-barcoding supported analysis of the mosquito fauna in the DDBR. The detection of two new species highlights the lack of knowledge about the mosquito fauna in Romania and in the DDBR in particular. The results provide detailed insights into the spatial-temporal mosquito species composition, which might lead to a better understanding of mobovirus activity in Romania and thus, can be used for the development of vector control programs.

The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence.

PubMed

Wang, Liang; Liu, Zhanzhong; Dai, Shiyun; Yan, Jiawei; Wise, Michael J

2017-01-01

The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald's (2004) review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/-) and durability (+/-) phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++), vector-borne pathogens (+-), obligate-intracellular bacteria (--), and free-living bacteria (-+). After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher host-mortality are significantly more durable in the external environment. The results of bioinformatics analysis correspond well with epidemiological data, that is, non-vector-borne pathogens with sit-and-wait potentials have higher number of virulence and durability genes compared with other bacterial groups. However, the conclusions are constrained by the relatively small bacterial sample size and non-standardized experimental data.

The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence

PubMed Central

Wang, Liang; Liu, Zhanzhong; Dai, Shiyun; Yan, Jiawei; Wise, Michael J.

2017-01-01

The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald’s (2004) review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/-) and durability (+/-) phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++), vector-borne pathogens (+-), obligate-intracellular bacteria (--), and free-living bacteria (-+). After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher host-mortality are significantly more durable in the external environment. The results of bioinformatics analysis correspond well with epidemiological data, that is, non-vector-borne pathogens with sit-and-wait potentials have higher number of virulence and durability genes compared with other bacterial groups. However, the conclusions are constrained by the relatively small bacterial sample size and non-standardized experimental data. PMID:29209284

Disentangling Vector-Borne Transmission Networks: A Universal DNA Barcoding Method to Identify Vertebrate Hosts from Arthropod Bloodmeals

PubMed Central

Alcaide, Miguel; Rico, Ciro; Ruiz, Santiago; Soriguer, Ramón; Muñoz, Joaquín; Figuerola, Jordi

2009-01-01

Emerging infectious diseases represent a challenge for global economies and public health. About one fourth of the last pandemics have been originated by the spread of vector-borne pathogens. In this sense, the advent of modern molecular techniques has enhanced our capabilities to understand vector-host interactions and disease ecology. However, host identification protocols have poorly profited of international DNA barcoding initiatives and/or have focused exclusively on a limited array of vector species. Therefore, ascertaining the potential afforded by DNA barcoding tools in other vector-host systems of human and veterinary importance would represent a major advance in tracking pathogen life cycles and hosts. Here, we show the applicability of a novel and efficient molecular method for the identification of the vertebrate host's DNA contained in the midgut of blood-feeding arthropods. To this end, we designed a eukaryote-universal forward primer and a vertebrate-specific reverse primer to selectively amplify 758 base pairs (bp) of the vertebrate mitochondrial Cytochrome c Oxidase Subunit I (COI) gene. Our method was validated using both extensive sequence surveys from the public domain and Polymerase Chain Reaction (PCR) experiments carried out over specimens from different Classes of vertebrates (Mammalia, Aves, Reptilia and Amphibia) and invertebrate ectoparasites (Arachnida and Insecta). The analysis of mosquito, culicoid, phlebotomie, sucking bugs, and tick bloodmeals revealed up to 40 vertebrate hosts, including 23 avian, 16 mammalian and one reptilian species. Importantly, the inspection and analysis of direct sequencing electropherograms also assisted the resolving of mixed bloodmeals. We therefore provide a universal and high-throughput diagnostic tool for the study of the ecology of haematophagous invertebrates in relation to their vertebrate hosts. Such information is crucial to support the efficient management of initiatives aimed at reducing epidemiologic risks of arthropod vector-borne pathogens, a priority for public health. PMID:19768113

Recurrent evolution of host and vector association in bacteria of the Borrelia burgdorferi sensu lato species complex.

PubMed

Becker, Noémie S; Margos, Gabriele; Blum, Helmut; Krebs, Stefan; Graf, Alexander; Lane, Robert S; Castillo-Ramírez, Santiago; Sing, Andreas; Fingerle, Volker

2016-09-15

The Borrelia burgdorferi sensu lato (s.l.) species complex consists of tick-transmitted bacteria and currently comprises approximately 20 named and proposed genospecies some of which are known to cause Lyme Borreliosis. Species have been defined via genetic distances and ecological niches they occupy. Understanding the evolutionary relationship of species of the complex is fundamental to explaining patterns of speciation. This in turn forms a crucial basis to frame testable hypotheses concerning the underlying processes including host and vector adaptations. Illumina Technology was used to obtain genome-wide sequence data for 93 strains of 14 named genospecies of the B. burgdorferi species complex and genomic data already published for 18 additional strain (including one new species) was added. Phylogenetic reconstruction based on 114 orthologous single copy genes shows that the genospecies represent clearly distinguishable taxa with recent and still ongoing speciation events apparent in Europe and Asia. The position of Borrelia species in the phylogeny is consistent with host associations constituting a major driver for speciation. Interestingly, the data also demonstrate that vector associations are an additional driver for diversification in this tick-borne species complex. This is particularly obvious in B. bavariensis, a rodent adapted species that has diverged from the bird-associated B. garinii most likely in Asia. It now consists of two populations one of which most probably invaded Europe following adaptation to a new vector (Ixodes ricinus) and currently expands its distribution range. The results imply that genotypes/species with novel properties regarding host or vector associations have evolved recurrently during the history of the species complex and may emerge at any time. We suggest that the finding of vector associations as a driver for diversification may be a general pattern for tick-borne pathogens. The core genome analysis presented here provides an important source for investigations of the underlying mechanisms of speciation in tick-borne pathogens.

Mosquitoes (Diptera: Culicidae) and their relevance as disease vectors in the city of Vienna, Austria.

PubMed

Lebl, Karin; Zittra, Carina; Silbermayr, Katja; Obwaller, Adelheid; Berer, Dominik; Brugger, Katharina; Walter, Melanie; Pinior, Beate; Fuehrer, Hans-Peter; Rubel, Franz

2015-02-01

Mosquitoes (Diptera: Culicidae) are important vectors for a wide range of pathogenic organisms. As large parts of the human population in developed countries live in cities, the occurrence of vector-borne diseases in urban areas is of particular interest for epidemiologists and public health authorities. In this study, we investigated the mosquito occurrence in the city of Vienna, Austria, in order to estimate the risk of transmission of mosquito-borne diseases. Mosquitoes were captured using different sampling techniques at 17 sites in the city of Vienna. Species belonging to the Culex pipiens complex (78.8 %) were most abundant, followed by Coquillettidia richiardii (10.2 %), Anopheles plumbeus (5.4 %), Aedes vexans (3.8 %), and Ochlerotatus sticticus (0.7 %). Individuals of the Cx. pipiens complex were found at 80.2 % of the trap sites, while 58.8 % of the trap sites were positive for Cq. richiardii and Ae. vexans. Oc. sticticus was captured at 35.3 % of the sites, and An. plumbeus only at 23.5 % of the trap sites. Cx. pipiens complex is known to be a potent vector and pathogens like West Nile virus (WNV), Usutu virus (USUV), Tahyna virus (TAHV), Sindbis virus (SINV), Plasmodium sp., and Dirofilaria repens can be transmitted by this species. Cq. richiardii is a known vector species for Batai virus (BATV), SINV, TAHV, and WNV, while Ae. vexans can transmit TAHV, USUV, WNV, and Dirofilaria repens. An. plumbeus and Oc. sticticus seem to play only a minor role in the transmission of vector-borne diseases in Vienna. WNV, which is already wide-spread in Europe, is likely to be the highest threat in Vienna as it can be transmitted by several of the most common species, has already been shown to pose a higher risk in cities, and has the possibility to cause severe illness.

Molecular Detection of Rickettsia africae in Amblyomma variegatum Collected from Sudan.

PubMed

Nakao, Ryo; Qiu, Yongjin; Salim, Bashir; Hassan, Shawgi Mohamed; Sugimoto, Chihiro

2015-05-01

Despite the increasing awareness of the importance of emerging vector-borne diseases, human tick-borne diseases, particularly rickettsial infections, are overlooked, especially in the countries such as Sudan with limited resources to perform molecular-based surveys. This study aimed at detection and genetic characterization of Rickettsia spp. in ticks collected from Sudan. The samples were first screened for the presence of rickettsial agents by gltA real-time PCR and subsequently characterized by gltA and ompA PCR and size-based multispacer typing. The results demonstrated the wide distribution of Rickettsia africae and/or closely related species across Sudan. The results of this report highlight the need for careful consideration of rickettsial infections in patients with nonmalarial febrile illness in this country. Nationwide surveillance on ticks associated with human rickettsial infections in Sudan is warranted.

Modeling vector-borne disease risk in migratory animals under climate change.

PubMed

Hall, Richard J; Brown, Leone M; Altizer, Sonia

2016-08-01

Recent theory suggests that animals that migrate to breed at higher latitudes may benefit from reduced pressure from natural enemies, including pathogens ("migratory escape"), and that migration itself weeds out infected individuals and lowers infection prevalence ("migratory culling"). The distribution and activity period of arthropod disease vectors in temperate regions is expected to respond rapidly to climate change, which could reduce the potential for migratory escape. However, climate change could have the opposite effect of reducing transmission if differential responses in the phenology and distribution of migrants and disease vectors reduce their overlap in space and time. Here we outline a simple modeling framework for exploring the influence of climate change on vector-borne disease dynamics in a migratory host. We investigate two scenarios under which pathogen transmission dynamics might be mediated by climate change: (1) vectors respond more rapidly than migrants to advancing phenology at temperate breeding sites, causing peak susceptible host density and vector emergence to diverge ("migratory mismatch") and (2) reduced migratory propensity allows increased nonbreeding survival of infected hosts and larger breeding-site epidemics (loss of migratory culling, here referred to as "sedentary amplification"). Our results highlight the need for continued surveillance of climate-induced changes to migratory behavior and vector activity to predict pathogen prevalence and its impacts on migratory animals. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Detection and molecular characterization of the mosquito-borne filarial nematode Setaria tundra in Danish roe deer (Capreolus capreolus).

PubMed

Enemark, Heidi Larsen; Oksanen, Antti; Chriél, Mariann; le Fèvre Harslund, Jakob; Woolsey, Ian David; Al-Sabi, Mohammad Nafi Solaiman

2017-04-01

Setaria tundra is a mosquito-borne filarial nematode of cervids in Europe. It has recently been associated with an emerging epidemic disease causing severe morbidity and mortality in reindeer and moose in Finland. Here, we present the first report of S. tundra in six roe deer ( Capreolus capreolus ) collected between October 2010 and March 2014 in Denmark. The deer originated from various localities across the country: the eastern part of the Jutland peninsular and four locations on the island Zealand. With the exception of one deer, with parasites residing in a transparent cyst just under the liver capsule, worms (ranging from 2 to >20/deer) were found free in the peritoneal cavity. The worms were identified as S. tundra by morphological examination and/or molecular typing of the mitochondrial 12S rRNA and cox1 genes, which showed 99.1-99.8% identity to previously published S. tundra isolates from Europe. Roe deer are generally considered as asymptomatic carriers and their numbers in Denmark have increased significantly in recent decades. In light of climatic changes which result in warmer, more humid weather in Scandinavia greater numbers of mosquitoes and, especially, improved conditions for development of parasite larvae in the mosquito vectors are expected, which may lead to increasing prevalence of S. tundra . Monitoring of this vector-borne parasite may thus be needed in order to enhance the knowledge of factors promoting its expansion and prevalence as well as predicting disease outbreaks.

The Effects of City Streets on an Urban Disease Vector

PubMed Central

Barbu, Corentin M.; Hong, Andrew; Manne, Jennifer M.; Small, Dylan S.; Quintanilla Calderón, Javier E.; Sethuraman, Karthik; Quispe-Machaca, Víctor; Ancca-Juárez, Jenny; Cornejo del Carpio, Juan G.; Málaga Chavez, Fernando S.; Náquira, César; Levy, Michael Z.

2013-01-01

With increasing urbanization vector-borne diseases are quickly developing in cities, and urban control strategies are needed. If streets are shown to be barriers to disease vectors, city blocks could be used as a convenient and relevant spatial unit of study and control. Unfortunately, existing spatial analysis tools do not allow for assessment of the impact of an urban grid on the presence of disease agents. Here, we first propose a method to test for the significance of the impact of streets on vector infestation based on a decomposition of Moran's spatial autocorrelation index; and second, develop a Gaussian Field Latent Class model to finely describe the effect of streets while controlling for cofactors and imperfect detection of vectors. We apply these methods to cross-sectional data of infestation by the Chagas disease vector Triatoma infestans in the city of Arequipa, Peru. Our Moran's decomposition test reveals that the distribution of T. infestans in this urban environment is significantly constrained by streets (p<0.05). With the Gaussian Field Latent Class model we confirm that streets provide a barrier against infestation and further show that greater than 90% of the spatial component of the probability of vector presence is explained by the correlation among houses within city blocks. The city block is thus likely to be an appropriate spatial unit to describe and control T. infestans in an urban context. Characteristics of the urban grid can influence the spatial dynamics of vector borne disease and should be considered when designing public health policies. PMID:23341756

Climate and the Timing of Imported Cases as Determinants of the Dengue Outbreak in Guangzhou, 2014: Evidence from a Mathematical Model

PubMed Central

Spear, Robert C.; Marshall, John M.; Yang, Zhicong; Gong, Peng

2016-01-01

As the world’s fastest spreading vector-borne disease, dengue was estimated to infect more than 390 million people in 2010, a 30-fold increase in the past half century. Although considered to be a non-endemic country, mainland China had 55,114 reported dengue cases from 2005 to 2014, of which 47,056 occurred in 2014. Furthermore, 94% of the indigenous cases in this time period were reported in Guangdong Province, 83% of which were in Guangzhou City. In order to determine the possible determinants of the unprecedented outbreak in 2014, a population-based deterministic model was developed to describe dengue transmission dynamics in Guangzhou. Regional sensitivity analysis (RSA) was adopted to calibrate the model and entomological surveillance data was used to validate the mosquito submodel. Different scenarios were created to investigate the roles of the timing of an imported case, climate, vertical transmission from mosquitoes to their offspring, and intervention. The results suggested that an early imported case was the most important factor in determining the 2014 outbreak characteristics. Precipitation and temperature can also change the transmission dynamics. Extraordinary high precipitation in May and August, 2014 appears to have increased vector abundance. Considering the relatively small number of cases in 2013, the effect of vertical transmission was less important. The earlier and more frequent intervention in 2014 also appeared to be effective. If the intervention in 2014 was the same as that in 2013, the outbreak size may have been over an order of magnitude higher than the observed number of new cases in 2014.The early date of the first imported and locally transmitted case was largely responsible for the outbreak in 2014, but it was influenced by intervention, climate and vertical transmission. Early detection and response to imported cases in the spring and early summer is crucial to avoid large outbreaks in the future. PMID:26863623

Natural Infection of the South American Tapir ( Tapirus terrestris ) by Theileria equi.

PubMed

Da Silveira, Alexandre Welzel; De Oliveira, Gustavo Gomes; Menezes Santos, Leandro; da Silva Azuaga, Lucas Bezerra; Macedo Coutinho, Claudia Regina; Echeverria, Jessica Teles; Antunes, Tamires Ramborger; do Nascimento Ramos, Carlos Alberto; Izabel de Souza, Alda

2017-04-01

Theileria equi is a tick-borne piroplasm considered endemic in equines in Brazil. The cohabitation of domestic and wild animals in areas of extensive cattle breeding favors the close contact between different species and the sharing of vectors and, consequently, pathogens. We report the natural infection of a young South American tapir ( Tapirus terrestris ) by T. equi in Mato Grosso do Sul, Brazil. Although it was not possible to associate the clinical and hematologic status of the animal with the infection by the protozoan parasite, our report represents an alert on the sharing of pathogens between domestic and wild animals.

Into the environment of mosquito-borne disease: A spatial analysis of vector distribution using traditional and remotely sensed methods

NASA Astrophysics Data System (ADS)

Brown, Heidi E.

Spatially explicit information is increasingly available for infectious disease modeling. However, such information is reluctantly or inappropriately incorporated. My dissertation research uses spatially explicit data to assess relationships between landscape and mosquito species distribution and discusses challenges regarding accurate predictive risk modeling. The goal of my research is to use remotely sensed environmental information and spatial statistical methods to better understand mosquito-borne disease epidemiology for improvement of public health responses. In addition to reviewing the progress of spatial infectious disease modeling, I present four research projects. I begin by evaluating the biases in surveillance data and build up to predictive modeling of mosquito species presence. In the first study I explore how mosquito surveillance trap types influence estimations of mosquito populations. Then. I use county-based human surveillance data and landscape variables to identify risk factors for West Nile virus disease. The third study uses satellite-based vegetation indices to identify spatial variation among West Nile virus vectors in an urban area and relates the variability to virus transmission dynamics. Finally, I explore how information from three satellite sensors of differing spatial and spectral resolution can be used to identify and distinguish mosquito habitat across central Connecticut wetlands. Analyses presented here constitute improvements to the prediction of mosquito distribution and therefore identification of disease risk factors. Current methods for mosquito surveillance data collection are labor intensive and provide an extremely limited, incomplete picture of the species composition and abundance. Human surveillance data offers additional challenges with respect to reporting bias and resolution, but is nonetheless informative in identifying environmental risk factors and disease transmission dynamics. Remotely sensed imagery supports mosquito and human disease surveillance data by providing spatially explicit, line resolution information about environmental factors relevant to vector-borne disease processes. Together, surveillance and remotely sensed environmental data facilitate improved description and modeling of disease transmission. Remote sensing can be used to develop predictive maps of mosquito distribution in relation to disease risk. This has implications for increased accuracy of mosquito control efforts. The projects presented in this dissertation enhance current public health capacities by examining the applications of spatial modeling with respect to mosquito-borne disease.

Malaria-induced changes in host odors enhance mosquito attraction

PubMed Central

De Moraes, Consuelo M.; Stanczyk, Nina M.; Betz, Heike S.; Pulido, Hannier; Sim, Derek G.; Read, Andrew F.; Mescher, Mark C.

2014-01-01

Vector-borne pathogens may alter traits of their primary hosts in ways that influence the frequency and nature of interactions between hosts and vectors. Previous work has reported enhanced mosquito attraction to host organisms infected with malaria parasites but did not address the mechanisms underlying such effects. Here we document malaria-induced changes in the odor profiles of infected mice (relative to healthy individuals) over the course of infection, as well as effects on the attractiveness of infected hosts to mosquito vectors. We observed enhanced mosquito attraction to infected mice during a key period after the subsidence of acute malaria symptoms, but during which mice remained highly infectious. This attraction corresponded to an overall elevation in the volatile emissions of infected mice observed during this period. Furthermore, data analyses—using discriminant analysis of principal components and random forest approaches—revealed clear differences in the composition of the volatile blends of infected and healthy individuals. Experimental manipulation of individual compounds that exhibited altered emission levels during the period when differential vector attraction was observed also elicited enhanced mosquito attraction, indicating that compounds being influenced by malaria infection status also mediate vector host-seeking behavior. These findings provide important insights into the cues that mediate vector attraction to hosts infected with transmissible stages of malaria parasites, as well as documenting characteristic changes in the odors of infected individuals that may have potential value as diagnostic biomarkers of infection. PMID:24982164

Malaria-induced changes in host odors enhance mosquito attraction.

PubMed

De Moraes, Consuelo M; Stanczyk, Nina M; Betz, Heike S; Pulido, Hannier; Sim, Derek G; Read, Andrew F; Mescher, Mark C

2014-07-29

Vector-borne pathogens may alter traits of their primary hosts in ways that influence the frequency and nature of interactions between hosts and vectors. Previous work has reported enhanced mosquito attraction to host organisms infected with malaria parasites but did not address the mechanisms underlying such effects. Here we document malaria-induced changes in the odor profiles of infected mice (relative to healthy individuals) over the course of infection, as well as effects on the attractiveness of infected hosts to mosquito vectors. We observed enhanced mosquito attraction to infected mice during a key period after the subsidence of acute malaria symptoms, but during which mice remained highly infectious. This attraction corresponded to an overall elevation in the volatile emissions of infected mice observed during this period. Furthermore, data analyses--using discriminant analysis of principal components and random forest approaches--revealed clear differences in the composition of the volatile blends of infected and healthy individuals. Experimental manipulation of individual compounds that exhibited altered emission levels during the period when differential vector attraction was observed also elicited enhanced mosquito attraction, indicating that compounds being influenced by malaria infection status also mediate vector host-seeking behavior. These findings provide important insights into the cues that mediate vector attraction to hosts infected with transmissible stages of malaria parasites, as well as documenting characteristic changes in the odors of infected individuals that may have potential value as diagnostic biomarkers of infection.

Investigation of spatiotemporal relationship between dengue fever and drought

NASA Astrophysics Data System (ADS)

Lee, Chieh-Han; Yu, Hwa-Lung

2016-04-01

Dengue Fever is a vector-borne disease that is transmitted between human and mosquitos in tropical and sub-tropical regions. Previous studies have found significant relationship between the epidemic of dengue cases and climate variables, especially temperature and precipitation. Besides, the natural phenomena (e.g., drought) are considered that significantly drop the number of dengue cases by killing vector's breeding environment. However, in Kaohsiung City, Taiwan, there are evidences that the temporal pattern of dengue is correlated to drought events. Kaohsiung City experienced two main dengue outbreaks in 2002 and 2014 that both years were confirmed with serious drought. Especially in 2014, Kaohsiung City was suffered from extremely dengue outbreak in 2014 that reported the highest number of dengue cases in the history. Otherwise, another nearby city, Tainan City, had reported the biggest outbreak in 2015. This study constructs the spatiotemporal model of dengue incidences and index of drought events (Standardized Precipitation Index, SPI) based on the distributed lag nonlinear model (DLNM). Other meteorological measures are also included in the analysis.

Quantifying and resolving multiple vector transformants in S. cerevisiae plasmid libraries.

PubMed

Scanlon, Thomas C; Gray, Elizabeth C; Griswold, Karl E

2009-11-20

In addition to providing the molecular machinery for transcription and translation, recombinant microbial expression hosts maintain the critical genotype-phenotype link that is essential for high throughput screening and recovery of proteins encoded by plasmid libraries. It is known that Escherichia coli cells can be simultaneously transformed with multiple unique plasmids and thusly complicate recombinant library screening experiments. As a result of their potential to yield misleading results, bacterial multiple vector transformants have been thoroughly characterized in previous model studies. In contrast to bacterial systems, there is little quantitative information available regarding multiple vector transformants in yeast. Saccharomyces cerevisiae is the most widely used eukaryotic platform for cell surface display, combinatorial protein engineering, and other recombinant library screens. In order to characterize the extent and nature of multiple vector transformants in this important host, plasmid-born gene libraries constructed by yeast homologous recombination were analyzed by DNA sequencing. It was found that up to 90% of clones in yeast homologous recombination libraries may be multiple vector transformants, that on average these clones bear four or more unique mutant genes, and that these multiple vector cells persist as a significant proportion of library populations for greater than 24 hours during liquid outgrowth. Both vector concentration and vector to insert ratio influenced the library proportion of multiple vector transformants, but their population frequency was independent of transformation efficiency. Interestingly, the average number of plasmids born by multiple vector transformants did not vary with their library population proportion. These results highlight the potential for multiple vector transformants to dominate yeast libraries constructed by homologous recombination. The previously unrecognized prevalence and persistence of multiply transformed yeast cells have important implications for yeast library screens. The quantitative information described herein should increase awareness of this issue, and the rapid sequencing approach developed for these studies should be widely useful for identifying multiple vector transformants and avoiding complications associated with cells that have acquired more than one unique plasmid.