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Leishmaniasis is a neglected tropical disease which kills an estimated 50,000 people each year, with its deadly impact confined mainly to lower to middle income countries. Leishmania parasites are transmitted to human hosts by sand fly vectors during blood feeding. Recent experimental work shows that transmission is modulated by the patchy landscape of infection in the host's skin, and the parasite population dynamics within the vector. Here we assimilate these new findings into a simple probabilistic model for disease transmission which replicates recent experimental results, and assesses their relative importance. The results of subsequent simulations, describing random parasite uptake and dynamics across multiple blood meals, show that skin heterogeneity is important for transmission by short-lived flies, but that for longer-lived flies with multiple bites the population dynamics within the vector dominate transmission probability. Our results indicate that efforts to reduce fly lifespan beneath a threshold of around two weeks may be especially helpful in reducing disease transmission., Competing Interests: The authors have declared that no competing interests exist.

Background: Triatomines are natural vectors of Chagas disease and are mainly prevalent in the Americas. In China, previous data from decades ago showed that there were two species of triatomine bugs, Triatoma rubrofasciata and T. sinica. However, the distribution, genetic characteristics and public health implications of triatomines in China are still relatively unknown. In order to gain knowledge on the distribution, genetic characteristics and public health implications of the triatomines in Guangxi, China, an entomological-epidemiological study and genetic research was conducted., Methods: Different methods were used to elucidate the distribution of triatomines in Guangxi including consultations with county-level Center for Disease Prevention and Control staff and village doctors, the distribution of educational material on triatomines though the internet and social media apps such as Wechat and QQ, and conducting manual inspections and light trapping to collect triatomines. The morphological characteristics of the collected triatomines were identified under light microscopy. The mitochondrial 16S rRNA, cytochrome b (cytb) genes and nuclear 28S rRNA gene were amplified, sequenced and used in phylogenetic analyses., Results: A total of 305 triatomines were captured from 54 different sites in 13 cities in Guangxi. All collected bugs were identified as T. rubrofasciata based on morphology. Most triatomine collection sites were around or inside houses. Four triatomines bite cases were observed during the investigation indicating that triatomine bites are common, the bites can cause serious anaphylaxis and skin papules and urticaria, suggesting a systemic skin response. The 16S rRNA, 28S rRNA and cytb sequence analyses of T. rubrofasciata from Guangxi and other countries showed that T. rubrofasciata sequences from different regions exhibit a high similarity, with no geographical differences. The phylogenetic tree based on the 16S rRNA and cytb genes showed that T. rubrofasciata sequences from different regions and continents were in the same cluster, indicating no differentiation among different geographical populations., Conclusions: Our study showed that T. rubrofasciata is widely distributed in Guangxi and that people are commonly bitten by this insect in some regions. This highlights the need to enhance surveillance for and control of T. rubrofasciata and to strengthen the monitoring of imported Trypanosoma cruzi in China. The 16S rRNA, 28S rRNA and cytb sequence analyses of T. rubrofasciata from different regions and continents suggested that T. rubrofasciata populations exhibit high similarity, and the clustering in the phylogenetic analyses indicates that T. rubrofasciata has a close ancestor originating in the Americas.

Leishmaniasis is a parasite disease transmitted by the bites of sandflies. Cutaneous leishmaniasis is the most common form of the disease and it is endemic in the Americas. Around 70 animal species, including humans, have been found as natural reservoir hosts of leishmania parasites. Among the reservoirs, dogs are the most important ones due to their proximity to the human habitat. Infection by leishmaniasis does not invariably cause illness in the host, and it also can remain asymptomatic for a long period, specially in dogs. In this work we formulate a model to study the transmission of the disease among the vector, humans and dogs. Our main objective is to asses the impact of dogs as a reservoir as well as the impact of asymptomatic humans and dogs on the spread of leishmaniasis. For this end we calculate the Basic Reproduction Number of the disease and we carry out sensitivity analysis of this parameter with respect to the epidemiological and demographic parameters., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Visceral leishmaniasis (VL) is a deadly neglected tropical disease that poses a serious problem in various countries all over the world. Implementation of various intervention strategies fail in controlling the spread of this disease due to issues of parasite drug resistance and resistance of sandfly vectors to insecticide sprays. Due to this, policy makers need to develop novel strategies or resort to a combination of multiple intervention strategies to control the spread of the disease. To address this issue, we propose an extensive SIR-type model for anthroponotic visceral leishmaniasis transmission with seasonal fluctuations modeled in the form of periodic sandfly biting rate. Fitting the model for real data reported in South Sudan, we estimate the model parameters and compare the model predictions with known VL cases. Using optimal control theory, we study the effects of popular control strategies namely, drug-based treatment of symptomatic and PKDL-infected individuals, insecticide treated bednets and spray of insecticides on the dynamics of infected human and vector populations. We propose that the strategies remain ineffective in curbing the disease individually, as opposed to the use of optimal combinations of the mentioned strategies. Testing the model for different optimal combinations while considering periodic seasonal fluctuations, we find that the optimal combination of treatment of individuals and insecticide sprays perform well in controlling the disease for the time period of intervention introduced. Performing a cost-effective analysis we identify that the same strategy also proves to be efficacious and cost-effective. Finally, we suggest that our model would be helpful for policy makers to predict the best intervention strategies for specific time periods and their appropriate implementation for elimination of visceral leishmaniasis.

Background: As part of a study to determine the impact of insecticide resistance on the effectiveness of long-lasting insecticide treated nets (LLINs) in the north of Cameroon, the unexpectedly high density and anthropophilic behaviour of Anopheles rufipes lead us to investigate this species bionomics and role in human malaria parasite transmission., Methods: For four consecutive years (2011-2014), annual cross-sectional sampling of adult mosquitoes was conducted during the peak malaria season (September-October) in three health districts in northern Cameroon. Mosquitoes sampled by human landing catch and pyrethrum spray catch methods were morphologically identified, their ovaries dissected for parity determination and Anopheles gambiae siblings were identified by molecular assay. Infection with P. falciparum and blood meal source in residual fauna of indoor resting anopheline mosquitoes were determined by enzyme-linked-immunosorbent assays., Results: Anopheles gambiae (sensu lato) (s.l.) comprised 18.4% of mosquitoes collected with An. arabiensis representing 66.27% of the sibling species. The proportion of An. rufipes (2.7%) collected was high with a human-biting rate ranging between 0.441 and 11.083 bites/person/night (b/p/n) and an anthropophagic rate of 15.36%. Although overall the members of An. gambiae complex were responsible for most of the transmission with entomological inoculation rates (EIR) reaching 1.221 infective bites/person/night (ib/p/n), An. arabiensis and An. coluzzii were the most implicated. The roles of An. funestus, An. pharoensis and An. paludis were minor. Plasmodium falciparum circumsporozoite protein rate in Anopheles rufipes varied from 0.6 to 5.7% with EIR values between 0.010 and 0.481 ib/p/n., Conclusions: The study highlights the epidemiological role of An. rufipes alongside the members of the An. gambiae complex, and several other sympatric species in human malaria transmission during the wet season in northern Cameroon. For the first time in Cameroon, An. rufipes has been shown to be an important local malaria vector, emphasising the need to review the malaria entomological profile across the country as pre-requisite to effective vector management strategies.

Background: Arboviral diseases are an important public health concerns. Vector control remains the sole strategy to fight against these diseases. Because of the important limits of methods currently used to assess human exposure to Aedes mosquito bites, much effort is being devoted to develop new indicators. Recent studies have reported that human antibody (Ab) responses to Aedes aegypti Nterm-34kDa salivary peptide represent a promising biomarker tool to evaluate the human-Aedes contact. The present study aims investigate whether such biomarker could be used for assessing the efficacy of vector control against Aedes., Methodology/principal Findings: Specific human IgG response to the Nterm-34kDa peptide was assessed from 102 individuals living in urban area of Saint-Denis at La Reunion Island, Indian Ocean, before and after the implementation of vector control against Aedes mosquitoes. IgG response decreased after 2 weeks (P < 0.0001), and remained low for 4 weeks post-intervention (P = 0.0002). The specific IgG decrease was associated with the decline of Aedes mosquito density, as estimated by entomological parameters and closely correlated to vector control implementation and was not associated with the use of individual protection, daily commuting outside of the house, sex and age. Our findings indicate a probable short-term decrease of human exposure to Aedes bites just after vector control implementation., Conclusion/significance: Results provided in the present study indicate that IgG Ab response to Aedes aegypti Nterm-34kDa salivary peptide could be a relevant short-time indicator for evaluating the efficacy of vector control interventions against Aedes species., Competing Interests: The authors have declared that no competing interests exist.

Chagas disease is a vector-borne and potentially fatal parasitic disease that is transmitted by the triatomine bug, a nocturnal feeding, flying arthropod, often referred to by its colloquial name, the "kissing bug." Vector-borne transmission is considered the most important means of spreading Chagas disease in endemic and nonendemic areas. Corrugated cardboard boxes may accelerate the spread of these insect vectors to nonendemic areas through their ability to harbor and transport small terrestrial arthropods such as silverfish, termites, and cockroaches. We report the case of a patient living in northern California who presented to a community clinic 6 weeks after being bitten by a positively identified triatomine bug. A local pest control company identified a total of eight adult Triatoma protracta, nine nymphs, and two eggs; all within the patient's bedding. No bugs were found outside of the patient's bedroom. The Centers for Disease Control and Prevention confirmed one adult female was positive for Trypanosoma cruzi via polymerase chain reaction. The patient's bedroom doubled as an office and regularly received and stored corrugated cardboard shipping boxes. Corrugated cardboard boxes have been used to trap and study the triatomine bug. This is the first documented case that provides circumstantial evidence that corrugated cardboard boxes may be an inadvertent and unrecognized factor in the spread of Chagas disease., (© The American Society of Tropical Medicine and Hygiene.)

Canine leishmaniasis (CanL) is a chronic fatal disease of dogs and a major source of human infection through propagation of parasites in vectors. Here, we infected 8 beagles through multiple experimental vector transmissions with Leishmania infantum-infected Lutzomyia longipalpis. CanL clinical signs varied, although live parasites were recovered from all dog spleens. Splenic parasite burdens correlated positively with Leishmania-specific interleukin 10 levels, negatively with Leishmania-specific interferon γ and interleukin 2 levels, and negatively with Leishmania skin test reactivity. A key finding was parasite persistence for 6 months in lesions observed at the bite sites in all dogs. These recrudesced following a second transmission performed at a distal site. Notably, sand flies efficiently acquired parasites after feeding on lesions at the primary bite site. In this study, controlled vector transmissions identify a potentially unappreciated role for skin at infectious bite sites in dogs with CanL, providing a new perspective regarding the mechanism of Leishmania transmissibility to vector sand flies., (© The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America.)

Comprehensive knowledge on vector dynamics is lacking in Botswana and yet essential for effective indoor residual spraying. This study assessed some of the entomological indices that contribute to malaria transmission by an indoor-resting population of Anopheles arabiensis Patton (Diptera: Culicidae) in Tubu village, Okavango subdistrict. The pyrethroid space-spray technique and hut searches were used to sample mosquitoes. Species and bloodmeal source identification were done using the polymerase chain reaction techniques. The infective status was determined by the enzyme-linked immuno-sorbent assay test. The human blood indices (HBI), human-biting rates (HBR), and vector densities were computed. Anopheles arabiensis was the sole vector and member of the Anopheles gambiae Giles complex identified. Significant changes in vector densities were observed over seasons, while nonsignificant differences were observed among the huts (P > 0.05). The main source of bloodmeal was cattle (46.8% [65]). There were no significant differences in HBI (P > 0.05) and HBR (P > 0.05) between the seasons. All the 271 mosquitoes tested for sporozoite infection were negative. The results showed that seasonal variations in vector densities corresponded to the traditional malaria and nonmalaria seasons. The vector population was relatively more zoophagic. The HBI and HBR were not influenced by the seasons. None of the endophilic mosquitoes tested (N = 271) was positive for sporozoites. Our study provided some relevant basic information to the local malaria control program that may be used to strategize their operations if malaria elimination has to be achieved by 2017., (© The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: During blood meal, the female mosquito injects saliva able to elicit an immune response in the vertebrate. This immune response has been proven to reflect the intensity of exposure to mosquito bites and risk of infection for vector transmitted pathogens such as malaria. The peptide gSG6-P1 of An. gambiae saliva has been demonstrated to be antigenic and highly specific to Anopheles as a genus. However, the applicability of gSG6-P1 to measure exposure to different Anopheles species endemic in the Americas has yet to be evaluated. The purpose of this pilot study was to test whether human participants living in American countries present antibodies able to recognize the gSG6-P1, and whether these antibodies are useful as a proxy for mosquito bite exposure and malaria risk., Methods: We tested human serum samples from Colombia, Chile, and the United States for the presence of IgG antibodies against gSG6-P1 by ELISA. Antibody concentrations were expressed as delta optical density (ΔOD) of each sera tested in duplicates. The difference in the antibody concentrations between groups was tested using the nonparametric Mann Whitney test (independent groups) and the nonparametric Wilcoxon matched-pairs signed rank test (dependent groups). All differences were considered significant with a P < 0.05., Results: We found that the concentration of gSG6-P1 antibodies was significantly correlated with malaria infection status and mosquito bite exposure history. People with clinical malaria presented significantly higher concentrations of IgG anti-gSG6-P1 antibodies than healthy controls. Additionally, a significant raise in antibody concentrations was observed in subjects returning from malaria endemic areas., Conclusion: Our data shows that gSG6-P1 is a suitable candidate for the evaluation of exposure to Anopheles mosquito bites, risk of malaria transmission, and effectiveness of protection measures against mosquito bites in the Americas.

Background: Malaria control in Africa relies heavily on indoor vector management, primarily indoor residual spraying and insecticide treated bed nets. Little is known about outdoor biting behaviour or even the dynamics of indoor biting and infection risk of sleeping household occupants. In this paper we explore the preferred biting sites on the human body and some of the ramifications regarding infection risk and exposure management., Methods: We undertook whole-night human landing catches of Anopheles arabiensis in South Africa and Anopheles gambiae s.s. and Anopheles funestus in Uganda, for seated persons wearing short sleeve shirts, short pants, and bare legs, ankles and feet. Catches were kept separate for different body regions and capture sessions. All An. gambiae s.l. and An. funestus group individuals were identified to species level by PCR., Results: Three of the main vectors of malaria in Africa (An. arabiensis, An. gambiae s.s. and An. funestus) all have a preference for feeding close to ground level, which is manifested as a strong propensity (77.3% - 100%) for biting on lower leg, ankles and feet of people seated either indoors or outdoors, but somewhat randomly along the lower edge of the body in contact with the surface when lying down. If the lower extremities of the legs (below mid-calf level) of seated people are protected and therefore exclude access to this body region, vector mosquitoes do not move higher up the body to feed at alternate body sites, instead resulting in a high (58.5% - 68.8%) reduction in biting intensity by these three species., Conclusions: Protecting the lower limbs of people outdoors at night can achieve a major reduction in biting intensity by malaria vector mosquitoes. Persons sleeping at floor level bear a disproportionate risk of being bitten at night because this is the preferred height for feeding by the primary vector species. Therefore it is critical to protect children sleeping at floor level (bednets; repellent-impregnated blankets or sheets, etc.). Additionally, the opportunity exists for the development of inexpensive repellent-impregnated anklets and/or sandals to discourage vectors feeding on the lower legs under outdoor conditions at night.

In the 19(th) century, a devastating epidemic of visceral leishmaniasis (kala-azar) swept through northeast India. After identification of the pathogenic agent, Leishmania donovani, in 1903, the question of its transmission remained to be resolved. In 1904, thanks to work by L. Rogers on cultures of this parasite it became probable that a haematophagous arthropod was responsible for transmission. J.A. Sinton suggested, in 1925, the distribution of the sand fly Phlebotomus argentipes was similar to that of the disease and, thereafter, two independent teams led by H.E. Shortt in Assam and R. Knowles and L. Napier in Calcutta concentrated on this potential vector. Parallel work was in progress in China, directed by E. Hindle and W. S. Patton for the Royal Society Kala-azar Commission, on another species of sand fly. In 1942 the Assam workers transmitted L. donovani to five human volunteers by the bites of colonised P. argentipes and the race was over.

Background: Visceral leishmaniasis (VL) is transmitted by sand flies. Protection of needle-challenged vaccinated mice was abrogated in vector-initiated cutaneous leishmaniasis, highlighting the importance of developing natural transmission models for VL., Methods: We used Lutzomyia longipalpis to transmit Leishmania infantum or Leishmania donovani to hamsters. Vector-initiated infections were monitored and compared with intracardiac infections. Body weights were recorded weekly. Organ parasite loads and parasite pick-up by flies were assessed in sick hamsters., Results: Vector-transmitted L. infantum and L. donovani caused ≥5-fold increase in spleen weight compared with uninfected organs and had geometric mean parasite loads (GMPL) comparable to intracardiac inoculation of 10(7)-10(8) parasites, although vector-initiated disease progression was slower and weight loss was greater. Only vector-initiated L. infantum infections caused cutaneous lesions at transmission and distal sites. Importantly, 45.6%, 50.0%, and 33.3% of sand flies feeding on ear, mouth, and testicular lesions, respectively, were parasite-positive. Successful transmission was associated with a high mean percent of metacyclics (66%-82%) rather than total GMPL (2.0 × 10(4)-8.0 × 10(4)) per midgut., Conclusions: This model provides an improved platform to study initial immune events at the bite site, parasite tropism, and pathogenesis and to test drugs and vaccines against naturally acquired VL.

Introduction: Few studies have described the factors associated with Plasmodium vivax transmission dynamics in endemic regions from Panamá., Objective: Malaria transmission dynamics produced by P. vivax were characterized at the border between Panamá and Costa Rica., Materials and Methods: In the municipality of Barú, an observational, descriptive and cross-sectional study was undertaken to measure the annual parasite index (API), slide positivity index (SPR), and the annual blood examination rate (ABER). The most frequent symptoms and signs in malaria patients were recorded. The anopheline species were identified in the area and the preferred larval habitats, the density of larval populations in the larval habitats and the bites/human/night were characterized., Results: Of a total of 10,401 thick smear blood samples, 83 were positive for P. vivax. Of these, 84% came from rural areas and 79% were from economically active individuals. The median and average ages were 36 and 30 years, respectively, and 58.5% of the malaria cases were male. API was 4.1/1,000 inhabitants; SPR was 0.8% and ABER was 51.9%. Of the diagnosed cases, 54% showed blood parasitemias ranging between 100-2,000 parasites/μl. The majority of the cases were observed in May and June. Two mosquito vector species were identified-- Anopheles albimanus and An. punctimacula., Conclusion: These observations indicate the advisibility of continued entomological studies, strengthening of epidemiological surveillance, consideration of additional risk factors and evaluation of work performance in the border region. This will require coordination with health authorities of both countries to control malaria in this region.

A high proportion of triatomine insects, vectors for Trypanosoma cruzi trypanosomes, collected in Arizona and California and examined using a novel assay had fed on humans. Other triatomine insects were positive for T. cruzi parasite infection, which indicates that the potential exists for vector transmission of Chagas disease in the United States.

Background: The knowledge of mosquito species diversity and the level of anthropophily exhibited by each species in a region are of great importance to the integrated vector control. Culicine species are the primary vectors of Japanese encephalitis (JE) virus and filariasis in China. Anopheles sinensis plays a major role in the maintenance of Plasmodium vivax malaria transmission in China. The goal of this study was to compare the abundance and host-seeking behavior of culicine species and An. sinensis in Yongcheng city, a representative region of P. vivax malaria. Specifically, we wished to determine the relative attractiveness of different animal baits versus human bait to culicine species and An. sinensis., Results: Culex tritaeniorhynchus was the most prevalent mosquito species and An. sinensis was the sole potential vector of P. vivax malaria in Yongcheng city. There were significant differences (P < 0.01) in the abundance of both An. sinensis and Cx. tritaeniorhynchus collected in distinct baited traps. The relative attractiveness of animal versus human bait was similar towards both An. sinensis and Cx. tritaeniorhynchus. The ranking derived from the mean number of mosquitoes per bait indicated that pigs, goats and calves frequently attracted more mosquitoes than the other hosts tested (dogs, humans, and chickens). These trends were similar across all capture nights at three distinct villages. The human blood index (HBI) of female An. sinensis was 2.94% when computed with mixed meals while 3.70% computed with only the single meal. 19:00~21:00 was the primary peak of host-seeking female An. sinensis while 4:00~5:00 was the smaller peak at night. There was significant correlation between the density of female An. sinensis and the average relative humidity (P < 0.05) in Wangshanzhuang village., Conclusions: Pigs, goats and calves were more attractive to An. sinensis and Cx. tritaeniorhynchus than dogs, humans, and chickens. Female An. sinensis host-seeking activity mainly occurred from 19:00 to 21:00. Thus, we propose that future vector control against An. sinensis and Cx. tritaeniorhynchus in the areas along the Huang-Huai River of central China should target the interface of human activity with domestic animals and adopt before human hosts go to bed at night., (© 2011 Liu et al; licensee BioMed Central Ltd.)

A complete picture of Chagas disease requires an appreciation of the many species of kissing bugs and their role in transmitting this disease to humans and other mammals. This chapter provides an overview of the taxonomy of the major species of kissing bugs and their evolution. Knowledge of systematics and biological kinship of these insects may contribute to novel and useful measures to control the bugs. The biology of kissing bugs, their life cycle, method of feeding and other behaviours contributing to the transmission of Trypanosoma cruzi are explained. We close with a discussion of vector control measures and the allergic complications of kissing bug bites, a feature of particular importance in the United States., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

We performed a longitudinal study of adult survival of Anopheles darlingi, the most important vector in the Amazon, in a malarigenous frontier zone of Brazil. Survival rates were determined from both parous rates and multiparous dissections. Anopheles darlingi human biting rates, daily survival rates and expectation of life where higher in the dry season, as compared to the rainy season, and were correlated with malaria incidence. The biting density of mosquitoes that had survived long enough for completing at least one sporogonic cycle was related with the number of malaria cases by linear regression. Survival rates were the limiting factor explaining longitudinal variations in Plasmodium vivax malaria incidence and the association between adult mosquito survival and malaria was statistically significant by logistic regression (P<0.05). Survival rates were better correlated with malaria incidence than adult mosquito biting density. Mathematical modeling showed that P. falciparum and P. malariae were more vulnerable to changes in mosquito survival rates because of longer sporogonic cycle duration, as compared to P. vivax, which could account for the low prevalence of the former parasites observed in the study area. Population modeling also showed that the observed decreases in human biting rates in the wet season could be entirely explained by decreases in survival rates, suggesting that decreased breeding did not occur in the wet season, at the sites where adult mosquitoes were collected. For the first time in the literature, multivariate methods detected a statistically significant inverse relation (P<0.05) between the number of rainy days per month and daily survival rates, suggesting that rainfall may cause adult mortality.

Background: Prior studies have shown that annual entomological inoculation rates (EIRs) must be reduced to less than one to substantially reduce the prevalence of malaria infection. In this study, EIR values were used to quantify the impact of insecticide-treated bed nets (ITNs), indoor residual spraying (IRS), and source reduction (SR) on malaria transmission. The analysis of EIR was extended through determining whether available vector control tools can ultimately eradicate malaria., Method: The analysis is based primarily on a review of all controlled studies that used ITN, IRS, and/or SR and reported their effects on the EIR. To compare EIRs between studies, the percent difference in EIR between the intervention and control groups was calculated., Results: Eight vector control intervention studies that measured EIR were found: four ITN studies, one IRS study, one SR study, and two studies with separate ITN and IRS intervention groups. In both the Tanzania study and the Solomon Islands study, one community received ITNs and one received IRS. In the second year of the Tanzania study, EIR was 90% lower in the ITN community and 93% lower in the IRS community, relative to the community without intervention; the ITN and IRS effects were not significantly different. In contrast, in the Solomon Islands study, EIR was 94% lower in the ITN community and 56% lower in the IRS community. The one SR study, in Dar es Salaam, reported a lower EIR reduction (47%) than the ITN and IRS studies. All of these vector control interventions reduced EIR, but none reduced it to zero., Conclusion: These studies indicate that current vector control methods alone cannot ultimately eradicate malaria because no intervention sustained an annual EIR less than one. While researchers develop new tools, integrated vector management may make the greatest impact on malaria transmission. There are many gaps in the entomological malaria literature and recommendations for future research are provided.

The border area between Suriname and French Guiana is considered the most affected malaria area in South America. A one-year cooperative malaria vector study was performed by the two countries, between March 2004 and February 2005, in four villages. Anopheles darlingi proved to be the most abundant anopheline species. Human biting rates differed between villages. The differential effect of high rainfall on mosquito densities in the villages suggests variation in breeding sites. Overall parity rates were low, with means varying from 0.31 to 0.56 per study site. Of the 2045 A. darlingi mosquitoes collected, 13 were found to be infected with Plasmodium: ten P. falciparum, two P. malariae and one mixed P. malariae/P. vivax. The overall annual entomological inoculation rates in the villages ranged from 8.7 to 66.4. There was an apparent lack of relationship between number of malaria cases and periods of high mosquito density. The tendency of Anopheles darlingi to bite during sleeping hours provides opportunity for malaria control using impregnated bed nets, a strategy just introduced in Suriname that may also find its way into French Guiana.

Culicoides biting midges (Diptera: Ceratopogonidae) are responsible for the spread of several arboviruses of livestock and humans that are of international importance. This study assesses the virulence of 18 insect-pathogenic fungal strains from the genera Metarhizium, Beauveria, Isaria and Lecanicillium to larval stages of Culicoides nubeculous Meigen as a means of examining their potential as biocontrol agents. In initial screening, six strains of M. anisopliae (ERL700, CA1, V275, LRC181A, ARSEF 3291 and ARSEF 4556) outperformed the other tested genera and were found to cause between 90% and 100% larval mortality in all larval instars of this species at 72 h post inoculation. The virulence of the most effective strain, M. anisopliae V275, was then further tested by exposing larvae to doses which ranged from 10(4)-10(8) conidia/ml and recording mortality at 24, 48 and 72 h in a 24-multi-well plate with each well containing 600 microl of water and at 24 and 48 h in 250 ml plastic cups containing 50 ml of water. Sensitivity of larvae was extremely high in the multi-well plates, with LC(50) values of 4.3-4.5 x 10(3)conidia/ml and no significant differences between larval instars. In the 250 ml cups, M. anisopliae V275 caused mortalities of between 70% and 100% to larvae and later instars exhibited higher mortality rates. The results are discussed in relation to incorporation of M. anisopliae into biocontrol programmes to control arboviruses vectored by Culicoides.

Background & Objectives: Investigations were conducted to obtain key entomological indices of Anopheles gambiae s.l. at Igbo-Ora, a rural community in south-west Nigeria., Methods: Mosquitoes were caught daily for a week from rooms where tenants had slept the previous night in each of the four months June, July (2001), and August, September (2002). Anopheles gambiae s.l. sibling species were PCR-identified, the blood meal origin was determined by direct ELISA, and the circumsporozoite antigen by sandwich ELISA. Mean weekly rates were calculated., Results: The mean human biting rates were 0.90 and 1.6 in 2001 and 2002 respectively. The mean weekly anthropophilic rates for An. gambiae s.l. were 82 and 86% in 2001 and 2002 respectively; they were high in An. gambiae s.s., An. arabiensis and non-identified species in the complex. The mean weekly circumsporozoite rates were 6.70% in 2001 and 6.30% in 2002. The mean weekly entomological inoculation rates (EIR) were 4.95 and 5.05 in 2001 and 2002 respectively; the seasonal (6-month) rates were high: 128.7 in 2001 and 131.3 in 2002, compared to data from other rural communities on the continent., Interpretation & Conclusion: The implications of these findings on the role of An. gambiae s.l. in the holoendemicity of malaria at Igbo-Ora are discussed.

Plasmodium falciparum malaria is a serious tropical disease that causes more than one million deaths each year, most of them in Africa. It is transmitted by a range of Anopheles mosquitoes and the risk of disease varies greatly across the continent. The "entomological inoculation rate" is the commonly-used measure of the intensity of malaria transmission, yet the methods used are currently not standardized, nor do they take the ecological, demographic, and socioeconomic differences across populations into account. To better understand the multiplicity of malaria transmission, this study examines the distribution of transmission intensity across sub-Saharan Africa, reviews the range of methods used, and explores ecological parameters in selected locations. It builds on an extensive geo-referenced database and uses geographical information systems to highlight transmission patterns, knowledge gaps, trends and changes in methodologies over time, and key differences between land use, population density, climate, and the main mosquito species. The aim is to improve the methods of measuring malaria transmission, to help develop the way forward so that we can better assess the impact of the large-scale intervention programmes, and rapid demographic and environmental change taking place across Africa.

To assess the role of Aedes albopictus in transmission of filarial nematodes of veterinary importance, researches were carried out in different geographical areas. In Italy a first research was performed to study the susceptibility of Ae. albopictus to Dirofilaria repens, D. immitis and Setaria labiatopapillosa. The development of L3 larvae was longer than in other species of mosquitoes but Ae. albopictus could be a suitable vector of filariae. To understand the role of Ae. albopictus in the natural transmission of Dirofilaria and to assess the risk for animal and human health, in 2000, 2001 and 2002 another study was carried out in the town of Padua. A total of 2,534 Ae. albopictus were caught on human-attracted mosquitoes. Specific primers and sequencing identified filarial DNA as D. immitis; Ae. albopictus was proved a natural vector of D. immitis. Similar results were confirmed in Central Italy also for D. repens. The presence of Ae. albopictus increased the probability of transmission of canine and human dirofilariosis in urban environment and it could change the epidemiology of dirofilariosis, in particular for what concern the time of biting and the risk season. These aspects must be considered to outline a correct prophylaxis.

The text summarizes the principal current fields of investigation and the recent achievements of the research groups presently contributing to the Molecular Entomology Cluster of the Italian Malaria Network. Particular emphasis is given to the researches with a more direct impact on the fight against malaria vectors.

Autochthonous transmission of the Chagas disease parasite, Trypanosoma cruzi, was detected in a patient in rural New Orleans, Louisiana. The patient had positive test results from 2 serologic tests and hemoculture. Fifty-six percent of 18 Triatoma sanguisuga collected from the house of the patient were positive for T. cruzi by PCR.

Transmission of Plasmodium falciparum is hyperendemic in southern Zambia. However, no data on the entomologic aspects of malaria transmission have been published from Zambia in more than 25 years. We evaluated seasonal malaria transmission by Anopheles arabiensis and An. funestus s.s. and characterized the blood feeding behavior of An. arabiensis in two village areas. Transmission during the 2004-2005 rainy season was nearly zero because of widespread drought. During 2005-2006, the estimated entomologic inoculation rate values were 1.6 and 18.3 infective bites per person per transmission season in each of the two village areas, respectively. Finally, with a human blood index of 0.923, An. arabiensis was substantially more anthropophilic in our study area than comparable samples of indoor-resting An. arabiensis throughout Africa and was the primary vector responsible for transmission of P. falciparum.

One of the most significant modern day efforts to prevent and control an arthropod-borne disease during a military deployment occurred when a team of U.S. military entomologists led efforts to characterize, prevent, and control leishmaniasis at Tallil Air Base (TAB), Iraq, during Operation Iraqi Freedom. Soon after arriving at TAB on 22 March 2003, military entomologists determined that 1) high numbers of sand flies were present at TAB, 2) individual soldiers were receiving many sand fly bites in a single night, and 3) Leishmania parasites were present in 1.5% of the female sand flies as determined using a real-time (fluorogenic) Leishmania-generic polymerase chain reaction assay. The rapid determination that leishmaniasis was a specific threat in this area allowed for the establishment of a comprehensive Leishmaniasis Control Program (LCP) over 5 mo before the first case of leishmaniasis was confirmed in a U.S. soldier deployed to Iraq. The LCP had four components: 1) risk assessment, 2) enhancement of use of personal protective measures by all personnel at TAB, 3) vector and reservoir control, and 4) education of military personnel about sand flies and leishmaniasis. The establishment of the LCP at TAB before the onset of any human disease conclusively demonstrated that entomologists can play a critical role during military deployments.

This article analyzes the results of a one-year entomological survey conducted near the Yalala rapids in the Inga region, Democratic Republic of Congo, prior to the implementation of Community-Directed Treatment with Ivermectin (CDTI). A vector control program had been undertaken from October 1969 to December 1980, 20 kilometers upstream from the study site. The results of the present study show that during 122 collection days, 5,824 females were captured, of which 3,899 were dissected; 2,001 (51.3%) were parous while 44 (2.2%) were infected while 4 (0.2%) were infective. The crude Annual Transmission Potential (ATP) was 65 infective larvae per man and per year at the river as against 12 in Yalala village located two kilometers from the rapids. The average biting rate was 5 flies/man/day during the dry season and 90 during the rainy season. The vector capacity of similium shows that the risk of transmission of Onchocerca volvulus to the human population was not only reduced in time (2-3 months), but was also negligible all year round.

Objective: To determine the biting activity and onchocerciasis transmission in Kashoya-Kitomi focus, Western Uganda., Design: Cross-sectional survey in randomly selected sites., Setting: Three districts in Western Uganda., Method: Crab trapping and examination for immature stages of Simulium neavei and full day human bait catches and dissections were conducted at three sites., Results: A total of 338 crabs were caught and out of this 372 (95.9%) were positive with immature stages of S. neavei with mean S. neavei/crab of 6.9. High biting density of S. neavei was observed in the two sites in Kabarole and Mbarara districts whereas an extremely low density was observed at a site in Bushenyi. Diurnal biting pattern revealed two peaks in the morning (09:00-10:00 hours.) and in the late afternoon (14:00-15:00 hours.) with a mid-day lull. The infection/infective rates were 53.3/11.0%, 30.7% to 7.8% and 20.0/0% for sites in Mbarara, Kabarole and Bushenyi districts, respectively. Monthly biting rates/ Transmission potentials for Mbarara, Kabarole and Bushenyi districts were 6231/5437, 9244/2916 and 247/0., Conclusion: There was high transmission of onchocerciasis observed in Kashoya-Kitomi focus despite the ongoing ivermectin treatment. The need for improved chemotherapeutic coverage and instituting other control measures may be necessary.

Objective: To study the risk of Trypanosoma cruzi domestic transmission using an entomological index and to explore its relationship with household's characteristics and cultural aspects., Methods: There were studied 158 households in an endemic area in Argentina. Each household was classified according to an entomological risk indicator (number of risky bites/human). A questionnaire was administered to evaluate risk factors among householders., Results: Infested households showed a wide range of risk values (0 to 5 risky bites/human) with skewed distribution, a high frequency of lower values and few very high risk households. Of all collected Triatoma infestans, 44% had had human blood meals whereas 27% had had dogs or chickens blood meals. Having dogs and birds sharing room with humans increased the risk values. Tidy clean households had contributed significantly to lower risk values as a result of low vector density. The infested households showed a 24.3% correlation between time after insecticide application and the number of vectors. But there was no correlation between the time after insecticide application and T. infestans' infectivity. The statistical analysis showed a high correlation between current values of the entomological risk indicator and Trypanosoma cruzi seroprevalence in children., Conclusions: The risk of T. cruzi domestic transmission assessed using an entomological index show a correlation with children seroprevalence for Chagas' disease and householders' habits.

An experiment was carried out in Burkina Faso to evaluate the potential for mechanical transmission of Trypanosoma vivax by the African tabanid Atylotus fuscipes. The experiment was carried out in a corral (10 m x 10 m) completely covered by a mosquito net (12 m x 12 m and 2.5m high). Eight heifers (cross-bred Zebu X Baoulé), free of trypanosome infection, were kept together with two heifers experimentally infected with a local stock of T. vivax. An average of 539 A. fuscipes per day, freshly captured with two Nzi traps, were introduced into the mosquito net from Day 1 to 20, to allow mechanical transmission of the parasites among cattle. Daily parasitological examinations (BCM) of cattle blood samples indicated that six of the eight receiver heifers were positive from days 9, 10, 15, 16, 19 and 29. Mechanical transmission of T. vivax by A. fuscipes was demonstrated unequivocally in close to natural conditions, at a high rate (75% incidence over a 20-day period) under a mean challenge of 54 insects per heifer per day. These results, in addition to previous demonstration of mechanical transmission of T. vivax by Atylotus agrestis, confirm that mechanical transmission can be a significant route of infection.

Investigations were carried out in Padova town (Veneto region, NE Italy) to define the actual role of Aedes albopictus in the natural transmission of Dirofilaria nematodes, and to assess the risk that its presence might represent for veterinary and medical health. During summer 2000-2002 daytime captures of human-attracted mosquitoes were carried out in three areas of the town. The presence of filarial parasites in mosquitoes was evaluated by PCR, and sequencing confirmed species assessment. DNA extraction was performed separately on pools of the insect abdomen and thorax-head, to discriminate between Dirofilaria infected/infective specimens. A total of 2721 mosquitoes were caught and A. albopictus was the most abundant species (2534). Filarial DNA was found in 27.5% (19/69) of the abdomen pools formed with mosquitoes collected in summer 2000, and in 11.1% (16/144) and 4.9% (6/123) thorax-head pools coming from samplings 2001 and 2002, respectively. Filarial DNA was belonging to D. immitis and all studied areas harboured infective specimens. These results prove A. albopictus as natural vector of D. immitis in Italy. Moreover, they support the hypothesis that the presence of the mosquito could affect the transmission pattern of canine heartworm disease in urban environment and, considering the aggressive anthropophylic behaviour of the species (30-48 bites/h) proven in Padova town, could enhance the circulation of filarial nematodes from animals to humans.

Phlebotomus sergenti is a natural vector of Leishmania tropica. However, the ability of P. sergenti to transmit L. tropica by bite has not been proven experimentally yet. We have transmitted L. tropica to golden hamsters and BALB/c mice by the bite of P. sergenti. Sand flies and Leishmania both originated from an anthroponotic cutaneous leishmaniasis focus in Urfa, Turkey. P. sergenti females from a laboratory colony were infected by feeding on lesions of needle-inoculated hamsters or mice. Gravid females were allowed to refeed on uninfected hosts 9-15 d after the infective feeding. At the second feeding, some infected females took a full blood meal, while others only a partial one; some females failed to feed at all. The ability of infected females to take a blood meal did not correlate with the parasite transmissibility. In four BALB/c mice, lesions developed after 1-6 months. In two albino hamsters (Mesocricetus auratus), lesions developed 1 month after the infective feeding, and Leishmania could be reisolated from these sites. Another hamster did not develop a lesion; however, the feeding site and the adjacent ear were PCR positive 1 year after infective feeding. Our results show that dissemination to other parts of host body occurs in L. tropica after sand fly bite. Experimental transmission of the parasite confirms that P. sergenti is a natural vector of L. tropica.

The role of mechanical vectors in the transmission of African livestock trypanosomes has always been controversial relative to tsetse flies, their cyclical vectors. An experiment was carried out in Burkina Faso to demonstrate mechanical transmission of Trypanosoma vivax by one of the most common tabanids in Africa: Atylotus agrestis. Eight heifers (crossbred zebuxBaoulé), free of trypanosome infection, were kept in a corral covered by a mosquito net, together with two heifers infected experimentally with a local stock of T. vivax. On average, 324 A. agrestis, freshly captured with Nzi traps, were introduced daily over 20 days. Parasitological, PCR and serological examinations were carried out regularly to assess infections and levels of parasitaemia. Microscopic examination of buffy-coats indicated that five of the eight receiver-heifers were infected on days 8, 13, 32, 41, and 48. PCR results indicated that these five heifers were already infected by day 13. Mechanical transmission of T. vivax by A. agrestis was demonstrated unequivocally, at a high rate (63% in 13-20 days). Conditions of transmission in this experiment are discussed in terms of natural rates of challenge. The importance of tabanids as mechanical vectors of T. vivax should be re-considered, in light of these results. Creation of tsetse free zones in Africa will generally lead to the disappearance of T. congolense, T. brucei, and most often T. vivax as well; however, in areas where T. vivax can be mechanically transmitted, clearance of tsetse may not be sufficient to eradicate livestock trypanosomosis.

Anophelines were sampled from 82 locations on Buka and Bougainville islands in Papua New Guinea by larval collections, carbon dioxide-baited mosquito traps, and human biting catches. Anopheles farauti s.s. was collected in larval surveys but infrequently in mosquito traps on both islands; on Buka Island this species was readily collected in human biting catches. Anopheles farauti 2 was commonly collected in larval surveys on both islands; however, it was not collected in either mosquito traps or human biting catches. Anopheles punctulatus was found only on Buka Island, where it was commonly collected as larvae, but rarely in human biting catches and mosquito traps. Anopheles lungae was collected as larvae from only 1 site on Bougainville. Anopheles farauti s.s. fed consistently throughout the night (1900-0600 h); small peaks at midnight and dawn were not statistically significant. Of 1,156 An. farauti s.s. specimens examined by enzyme-linked immunosorbent assay for malaria sporozoites, 20 were found to be positive; 12 were positive for Plasmodium falciparum and 8 were positive for P. vivax (247 variant = 5; 210 variant = 3). Anopheles farauti s.s. seems to be the major malaria vector on these islands, whereas An. punctulatus may play a minor role on Buka Island. Anophele jarauti 2 is unlikely to be involved in malaria transmission on Buka or Bougainville islands.

Canine visceral leishmaniasis (VL), caused by Leishmania infantum (Leishmania chagasi in the New World), is a zoonotic, endemic disease in Western Europe and Latin America. The potential spreading to new regions was suggested by the appearance of canine VL among foxhounds in the US. Although the sand fly vectors in the major foci of transmission have been described, no information exists on other sand flies that could propagate the infection outside endemic areas. We evaluated the capacity of Lutzomyia shannoni (Dyar) and Lutomyia youngi (Feliciangeli & Murillo), which are widely distributed in the New World, to acquire L chagasi (Cunha and Chagas) infections. A high proportion of L youngi were infected after feeding on an oligosymptomatic dog (51 per cent) or a polysymptomatic individual (95 per cent), but the intensity of infection was low (< 200 promastigotes/fly). L shannoni became infected only by feeding on the polysymptomatic dog, and the infection rate was lower (9 per cent) than in Lutzomyia longipalpis (36 per cent), and Lutzomyia evansi (Nunez-Tovar) (Lutz and Neiva) (38 per cent), but the intensity of infection (200 to > 500 promastigotes/fly) was comparable (L longipalpis) or higher (L evansi) than in the New World vectors. It is hypothesised that the presence of infected dogs in areas where L shannoni or L youngi occur could initiate new endemic cycles of VL in both South and North America.

Much progress has been made in describing how it is, in a mechanistic sense, that some vertebrate hosts (species or individuals) are bitten more than others, principally because of their odour or appearance. Little attention has been paid to why, in an evolutionary sense, these particular animals are bitten. Irrespective of the proximate mechanisms of host choice, there must be an intense selection pressure on insects to feed on those hosts that are most amenable to being bitten. We should be better able to predict host choice by understanding the evolutionary processes at work.

Nowadays, malaria control is planned according to the epidemiological context. Various aspects of malaria have been described in sub-Saharan Africa. We report here entomological data from the coastal area of Benin, West Africa, which has many lakes and lagoons. We carried out a longitudinal study in which we investigated the dynamics of populations of malaria vectors in various zones, the frequency of inoculation in these zones, the infestation rate of the Anopheles gambiae mosquitoes collected, the effect of urbanization on malaria transmission, the effects of inundation and of salinity at mosquito breeding sites. A total of 3, 342 identifications were made on a chromosomal basis. Two species of the Anopheles gambiae complex were detected in the coastal and lagoon areas of Benin: An. melas and An. gambiae ss. The density of the populations of these species was highly dependent on the level of urbanization. In traditional villages on the lagoons (such as Agbalilamè, Djegbadji and Kétonou), the density of An. melas (86. 2%) was much higher than that in more urbanized areas (such as Ladji and Abomey-Calavi) (4.9%). We checked for chromosome polymorphism. We detected a 2Rn1 inversion in An. melas, similar to the 2Rn inversion found in mosquitoes in Gambia and Guinea-Bissau. The frequency of the n1 inversion and the density of An. melas populations were correlated and both seemed to depend on a single factor, salinity. The epidemiological situation with respect to malaria was very heterogeneous in the lagoon area of Benin. In the city of Cotonou, transmission was seasonal, sporozoite indices and the frequency of inoculation were high, in contrast to what would normally be expected in an urban area. In communities built on the beach, the level of transmission was markedly lower: about 5 infected bites per person per year versus 29 infected bites per person in the center of the city. In the traditional fishing villages, a paradoxical situation was observed in which the mosquitoes were very aggressive towards humans (4,502 bites per person per year) but the frequency of transmission was low (d = 0. 27%, CS+ = 0.57%). This was largely due to the high density in this area of An. melas, a poor malaria vector. If traditional villages become more urbanized, more freshwater breeding sites are created and the An. gambiae population increases, leading to an increase in malaria transmission. This is the reason for the higher level of malaria transmission at Ladji and Abomey-Calavi (h = 47 infected bites per person per year) than at Agbailamè, Djegbadji and Kétonou (h = 12.1 infected bites per person per year)

Existing models of the basic case reproduction number (R0) for vector-borne diseases assume (i) that the distribution of vectors over the susceptible host species is homogeneous and (ii) that the biting preference for the susceptible host species rather than other potential hosts is a constant. Empirical evidence contradicts both assumptions, with important consequences for disease transmission. In this paper we develop an Ideal Free Distribution (IFD) model of host choice by blood-sucking insects, predicated on the argument that vectors must have evolved to choose the least defensive hosts in order to maximize their feeding success. From a re-analysis of existing data, we demonstrate that the interference constant, m, of the IFD can vary between host species. As a result, the predicted distribution of insects over hosts has 2 desirable and intuitively plausible behaviours: that it is heterogeneous both within and between host species; and that the intensity of heterogeneity varies with host and vector density. When the IFD model is incorporated into R0, the relationship with the vector:host ratio becomes non-linear. If correct, the IFD could add considerable realism to models which seek to predict the effect of these ecological parameters on disease transmission as they vary naturally (e.g. through seasonality in vector density or host population movement) or as a consequence of artificial manipulation (e.g. zooprophylaxis, vector control). It raises the possibility of targeting transmission hot spots with greater accuracy and concomitant reduction in control effort. The robustness of the model to simplifying assumptions is discussed.

A longitudinal study on malaria vectors and transmission was carried out in a forest-savannah transitional area in Cameroon. Indoor all night mosquito collections on human bait were performed during one year in two villages: Nditam and Ngoume. Nditam was located in a secondary forest block surrounded by savannah, while Ngoume was situated in an ancient forest block. The results showed that at Nditam, only one anopheline species was collected, that was Anopheles gambiae s.l.. The average daily biting rate was 2.4 bites per man per night. The sporozoitic index of An. gambiae was 9.4%. The entomological inoculation rate was therefore estimated at 0.225 infective bite per man per night that is to say 82 infective bites per man per year. Malaria transmission was low during the year, but an important increase was observed in September, when the rainfall was at its peak. At Ngoume, no Anopheles mosquito was collected. Therefore, malaria transmission was not observed in that village.

A new concept of medical entomology is proposed, according to which this discipline should comprehensively study the effects of arthropods on human health and possible control of these effects. Thus, the tasks of medical entomology are markedly widened to embrace cognitively and practically important problems, which have been neglected. This approach does not negate the accepted understanding of medical entomology but includes it as an essential component.

Larvae of Simulium damnosum complex collected from rivers draining Tukuyu onchocerciasis focus were chromosomally examined. Of the 970 larvae analysed, 910 were identified as Kiwira form, a newly described cytotype found in all S. damnosum larval habitats in the Tukuyu area, while 51 were classified as a new subpopulation, tentatively named as Kasyabone form. The F1 larval progeny obtained from wild caught human biting S. damnosum and reared in the laboratory were chromosomally examined. 509 F1 larvae from 70 females blood fed on human volunteers were identified as Kiwira form. As the main human-biting member of the complex in the Tukuyu area, and because some of the wild caught females had developing filarial larvae indistinguishable from those of Onchocerca volvulus, Kiwira form is thus incriminated as the local vector of onchocerciasis. These observations are discussed with respect to previous literature.

Biting fly behavior involved in parasite transmission is reviewed. Except for the areas of activity and probing, few investigations have addressed ways in which parasites might alter vector behavior. Given the manner in which parasites alter behavior in other arthropods (e.g., habitat choice, color preference), it is reasonable to expect infected hematophagous flies to behave differently from uninfected conspecifics. This could have important epidemiological consequences.