Peridomestic Habitats Research Articles

Feeding sources and trypanosome infection index of Rhodnius pallescens in a Chagas disease endemic area of Amador County, Panama

The sylvatic triatomine Rhodnius pallescens is considered to be the most important and widespread vector of Trypanosoma cruzi and Trypanosoma rangeli in Panama. However, its behavior and biological characteristics have only been partially investigated. Thus, to achieve sustainable and efficient control over Chagas disease in Panama, a better understanding of the ecology and biology of R. pallescens is essential. In this study we evaluated R. pallescens host feeding sources using a dot-blot assay, and the trypanosome infection index by PCR analysis in a Chagas disease endemic area of central Panama. It was found that in peridomestic palm trees, 20.3% of the examined bugs had fed on opossums (Didelphis marsupialis). However, we observed an increased anthropophagy (25.4%) for those bugs collected inside houses. Considering the domestic and peridomestic habitats as a whole, the proportion of collected R. pallescens infected with trypanosomes was 87.4%. In the two habitats the predominant infection was with T. cruzi (80-90%). Between 47-51% of the analyzed triatomines were infected with T. rangeli. Mixed infections (40-51%) were also detected. These findings provide a better basis for the implementation of a rational control and surveillance program for Chagas disease in regions where R. pallescens is endemic.

Microsatellites reveal a high population structure in Triatoma infestans from Chuquisaca, Bolivia.

BackgroundFor Chagas disease, the most serious infectious disease in the Americas, effective disease control depends on elimination of vectors through spraying with insecticides. Molecular genetic research can help vector control programs by identifying and characterizing vector populations and then developing effective intervention strategies.Methods and FindingsThe population genetic structure of Triatoma infestans (Hemiptera: Reduviidae), the main vector of Chagas disease in Bolivia, was investigated using a hierarchical sampling strategy. A total of 230 adults and nymphs from 23 localities throughout the department of Chuquisaca in Southern Bolivia were analyzed at ten microsatellite loci. Population structure, estimated using analysis of molecular variance (AMOVA) to estimate FST (infinite alleles model) and RST (stepwise mutation model), was significant between western and eastern regions within Chuquisaca and between insects collected in domestic and peri-domestic habitats. Genetic differentiation at three different hierarchical geographic levels was significant, even in the case of adjacent households within a single locality (R ST = 0.14, F ST = 0.07). On the largest geographic scale, among five communities up to 100 km apart, R ST = 0.12 and F ST = 0.06. Cluster analysis combined with assignment tests identified five clusters within the five communities.ConclusionsSome houses are colonized by insects from several genetic clusters after spraying, whereas other households are colonized predominately by insects from a single cluster. Significant population structure, measured by both R ST and F ST, supports the hypothesis of poor dispersal ability and/or reduced migration of T. infestans. The high degree of genetic structure at small geographic scales, inferences from cluster analysis and assignment tests, and demographic data suggest reinfesting vectors are coming from nearby and from recrudescence (hatching of eggs that were laid before insecticide spraying). Suggestions for using these results in vector control strategies are made.

Defective Rainwater Harvesting Structure and Dengue Vector Productivity Compared with Peridomestic Habitats in a Coastal Town in Southern India

Productivity of defective rainwater harvesting structures (RWHS) and other peridomestic habitats for dengue vector was assessed in a coastal town in Tamil Nadu, southern India, where dengue cases were reported. Of 31,709 houses, 792, 790, and 759 were surveyed during southwest monsoon, northeast monsoon, and summer season, and RWHS were found in 651, 638, and 544 houses, respectively. Of these RWHS, 23.3, 34.6 and 14.2% had defects; 20.7, 30.9, and 11.8% were holding water; and 6.5, 11.9, and 5.7% supported dengue vectors. Six types of RWHS, namely, open percolation pit, covered percolation pit, sealed percolation pit, rechargeable trench with bore, and structures connected to well in use or disuse were found. Number of female pupae of Aedes, i.e., pupal productivity obtained from RWHS ranged from 114 in summer to 1,174 in northeast monsoon, and open percolation pit contributed maximum (11.5%). The productivity of habitats other than RWHS varied from 635 in summer to 1,754 in northeast monsoon. Overall, the pupal productivity recorded from RWHS was 30.1% and in other habitats was 69.9%. A hierarchical cluster analysis showed three clusters of 23 types of habitats, which differed significantly in pupal production (F = 426.4, P < 0.05). Cluster I consists of 15 habitats, namely, disused well, RWHS-disused well, RWHS-used well, metal container, coconut shell, glass bottle, sealed percolation pit, used well, ornamental container, tree stump, defrost water collection tray, disposable cup, flower pot, broken toilet ware, and sun shade. Cluster II includes seven habitats, i.e., grinding stone, open percolation pit, covered percolation pit, cement tank, mud pot, plastic container, and rechargeable trench with bore, and cluster III includes automobile tire alone. Cluster II and III contributed to 80.1% of the total pupal production, whereas the remaining 19.9% by cluster I. The study showed that the defective RWHS, particularly open and covered percolation pits were found to be among the key containers, propagating Aedes population. The pupae per person obtained during northeast monsoon in different houses varied between 0.077 and 2.839 (average 0.864). House and Breteau Indices were relatively higher during northeast monsoon, whereas the Container Index was higher in southwest monsoon. In view of risk of dengue vectors propagation, the need for source reduction involving community and prioritizing control measures toward the highly productive water-holdings is discussed.

Defective Rainwater Harvesting Structure and Dengue Vector Productivity Compared with Peridomestic Habitats in a Coastal Town in Southern India

Productivity of defective rainwater harvesting structures (RWHS) and other peridomestic habitats for dengue vector was assessed in a coastal town in Tamil Nadu, southern India, where dengue cases were reported. Of 31,709 houses, 792, 790, and 759 were surveyed during southwest monsoon, northeast monsoon, and summer season, and RWHS were found in 651, 638, and 544 houses, respectively. Of these RWHS, 23.3, 34.6 and 14.2% had defects; 20.7, 30.9, and 11.8% were holding water; and 6.5, 11.9, and 5.7% supported dengue vectors. Six types of RWHS, namely, open percolation pit, covered percolation pit, sealed percolation pit, rechargeable trench with bore, and structures connected to well in use or disuse were found. Number of female pupae of Aedes, i.e., pupal productivity obtained from RWHS ranged from 114 in summer to 1,174 in northeast monsoon, and open percolation pit contributed maximum (11.5%). The productivity of habitats other than RWHS varied from 635 in summer to 1,754 in northeast monsoon. Overall, the pupal productivity recorded from RWHS was 30.1% and in other habitats was 69.9%. A hierarchical cluster analysis showed three clusters of 23 types of habitats, which differed significantly in pupal production (F = 426.4, P < 0.05). Cluster I consists of 15 habitats, namely, disused well, RWHS-disused well, RWHS-used well, metal container, coconut shell, glass bottle, sealed percolation pit, used well, ornamental container, tree stump, defrost water collection tray, disposable cup, flower pot, broken toilet ware, and sun shade. Cluster II includes seven habitats, i.e., grinding stone, open percolation pit, covered percolation pit, cement tank, mud pot, plastic container, and rechargeable trench with bore, and cluster III includes automobile tire alone. Cluster II and III contributed to 80.1% of the total pupal production, whereas the remaining 19.9% by cluster I. The study showed that the defective RWHS, particularly open and covered percolation pits were found to be among the key containers, propagating Aedes population. The pupae per person obtained during northeast monsoon in different houses varied between 0.077 and 2.839 (average 0.864). House and Breteau Indices were relatively higher during northeast monsoon, whereas the Container Index was higher in southwest monsoon. In view of risk of dengue vectors propagation, the need for source reduction involving community and prioritizing control measures toward the highly productive water-holdings is discussed.

Behavioral Plasticity of Triatominae Related to Habitat Selection in Northeast Brazil

Triatoma pseudomaculata Corrêa and Espínola, 1964 and Triatoma juazeirensis (=T. brasiliensis Neiva, 1911 [part]), are sylvatic vectors of Trypanosoma cruzi (Chagas, 1909), the causative agent of Chagas disease, in northeast Brazil—especially in the caatinga region. In an area of caatinga in the State of Bahia, we compared the wild and peridomestic habitats of these two species of Triatominae to assess their behavioral plasticity in relation to habitat selection in different environments. In the sylvatic environment, the habitat of these two species is never shared. T. pseudomaculata is found in trees and bird nests, but without apparent preference for any particular tree species. In contrast, T. juazeirensis is exclusively rupicolous (found among rocks). Both species invade peridomestic structures but do not display a significant ability to colonize human dwellings. In the peridomestic area, they are highly adaptable to different habitats and can occupy substrates that they do not colonize in the sylvatic environment. This behavioral plasticity seems to be more striking in T. juazeirensis—rupicolous in sylvatic environments but colonizing wooden structures in the peridomicile in >80% of cases.

Behavioral Plasticity of Triatominae Related to Habitat Selection in Northeast Brazil

Triatoma pseudomaculata Corrêa and Espínola, 1964 and Triatoma juazeirensis Costa and Felix, 2007 ( = T. brasiliensis Neiva, 1911 [part]), are sylvatic vectors of Trypanosoma cruzi (Chagas, 1909), the causative agent of Chagas disease, in northeast Brazil-especially in the caatinga region. In an area of caatinga in the State of Bahia, we compared the wild and peridomestic habitats of these two species of Triatominae to assess their behavioral plasticity in relation to habitat selection in different environments. In the sylvatic environment, the habitat of these two species is never shared. T. pseudomaculata is found in trees and bird nests, but without apparent preference for any particular tree species. In contrast, T. juazeirensis is exclusively rupicolous (found among rocks). Both species invade peridomestic structures but do not display a significant ability to colonize human dwellings. In the peridomestic area, they are highly adaptable to different habitats and can occupy substrates that they do not colonize in the sylvatic environment. This behavioral plasticity seems to be more striking in T. juazeirensis-rupicolous in sylvatic environments but colonizing wooden structures in the peridomicile in >80% of cases.

Group discussion: epidemiological, social, and control determinants of Chagas disease in Central America and Mexico

The existence of Chagas disease in Central Americawas reported for the first time in El Salvador in 1913,four years after its discovery in Brazil. At that time onlyTriatoma dimidiata was known as a vector, but two yearslater, in the same country, Rhodnius prolixus was dis-covered, which is a more efficient vector and now con-sidered to be an introduced species in the area.Several epidemiological and clinical studies haveshown that, with the exception of Belize, the disease isendemic in all Central American countries and in cer-tain areas has become a serious public health problem.This led the health authorities of the countries to launchthe Central American Initiative for the control of Chagasdisease in 1997. Since that date, several actions havetaken place, aiming to eliminate R. prolixus from theregion, lower vectorial transmission by T. dimidiata , andcontrol transmission by blood transfusion.Summary of the discussion of Dr Ponce paperDr Zeledon - I would like to add two important epi-demiological facts related to the situation in Nicaragua:the recent finding of R. pallescens in the DepartmentRio San Juan, on the border with Costa Rica, and the pres-ence, in some departments of the northeast and south-east of the country, of T. ryckmani.The presence of a species of Rhodnius in Rio SanJuan, led the Ministry of Health personnel to spray 2000houses with insecticide convinced it was R. prolixus untilit was realized that the species present in the area wasactually R. pallescens . The latter has been found mainlyin the peridomiciles but in at least four houses somenymphs were also found indoors, suggesting an initia-tion of colonization of those houses. A serological sur-vey in school children yielded 6.7% of positive tests and inspite of the occasional finding of T. dimidiata, R. pal-lescens seem to be an important vector in the area. On theCosta Rican side, R. pallescens is only a visitor of housesand the seroprevalence there, also in school children, islow (0.24%). In both sides across the border, R. pallescenshas been found in palm trees (Attalea butyracea).In relation to T. ryckmani, the species is becoming afrequent visitor inside and outside houses where adultsare attracted to lights. In Guatemala, the species has beenfound living in bromeliads of the genus Tillandsia insemiarid regions of the country and in a few instances itis able to colonize human dwellings. The bromeliadswhere this bug breeds, are used locally for decorationsand are also exported abroad and this could become amechanism for dissemination of the insect.Another aspect worth mentioning is in reference toenvironmental management methods for the control ofT. dimidiata as was recommended in a technical work-shop on the species held in San Salvador in 2002. A pi-lot project was implemented in Costa Rica by modify-ing the environment around a group of houses in orderto destroy the peridomestic habitats and make difficultthe colonization of the bug in those areas, with very prom-ising results.Going back to the hypothesis that R. prolixus is anexotic species in Central America, the idea originated in1995 in the ECLAT meeting of Santo Domingo de losColorados, Ecuador. After the meeting, Dr Ponce wasable to transmit the idea of a possible elimination of thespecies to the Minister of Health of Honduras who mean-while was able to convince the health authorities of theother countries to include this premise as an objectiveof the Central American Initiative for the control ofChagas diseases, which was created, also at the requestof Honduran authorities, two years later. This is a goodexample of a scientist transferring knowledge and ad-vising a politician, leading to the political will of con-verting it into action.Dr Ponce - It is possible that R. prolixus could dis-appear from Central America within the next two years.Dr Silveira - It is unacceptable as an aim of the Cen-tral American Initiative just the reduction of the infesta-tion by T. dimidiata. Reduction to which level? Does itcorrespond to the control of the domiciliary transmis-sion or just to the interruption of transmission? In thecase of autochthonous vectors the “possible” level ofcontrol of the vector is the elimination of its intrado-miciliary colonies avoiding its re-colonization throughcommon entomological surveillance actions.Dr Ponce - I agree.Dr Silveira - Was the protocol for interventions onR. pallescens in Panama, proposed by a team during aninternational evaluation in that country, finally applied?Dr Ponce - Not yet due to changes in personnel inthe country but is being considered at present.

The first records of Leishmania ( Leishmania) amazonensis in dogs ( Canis familiaris) diagnosed clinically as having canine visceral leishmaniasis from Araçatuba County, São Paulo State, Brazil

Two cases of Leishmania ( Leishmania) amazonensis are reported in the domestic dog ( Canis familiaris). These are the first records of this parasite in this species. The animals lived in the endemic visceral leishmaniasis area of Araçatuba, São Paulo State, Brazil and were initially diagnosed, on clinical grounds, as having visceral leishmaniasis. Attempted parasite isolation from inguinal lymph node aspirates was unsuccessful and the indirect immunofluorescent test for visceral leishmaniasis was negative in both cases. Parasites were seen in cytological preparations of their lymph nodes and the DNA obtained from these same tissues produced the expected fragment in a Leishmania specific rDNA based PCR assay. The products only hybridized with the L. ( L.) amazonensis specific probe S8. No human cases of L. ( L.) amazonensis have been reported in this region. These results suggest that L. ( L.) amazonensis is being transmitted in the peridomestic habitat and that this parasite is responsible for a clinical condition that is similar to visceral leishmaniasis caused by L. ( L.) i. chagasi that is present in the same area.

GENETIC STRUCTURE OF LUTZOMYIA (NYSSOMYIA) INTERMEDIA POPULATIONS FROM TWO ECOLOGIC REGIONS IN BRAZIL WHERE TRANSMISSION OF LEISHMANIA (VIANNIA) BRAZILIENSIS REFLECTS DISTINCT ECO-EPIDEMIOLOGIC FEATURES

Randomly amplified polymorphic DNA (RAPD) analysis was performed to infer the magnitude and pattern of genetic differentiation among Lutzomyia (Nyssomyia) intermedia populations from two ecologic regions in southeast Brazil where transmission of American cutaneous leishmaniasis (ACL) by L. (Viannia) braziliensis reflects distinct eco-epidemiologic features. Two hundred thirty-five bands from six primers were analyzed for genetic variation within and between sand fly populations. A lower level of intrapopulational variability was found in domestic sand flies (compared with the peridomestic population). Gene flow FST estimates indicated homogeneity in the studied population, with limited population substructuring, but with a tendency of sand fly vectors to form clusters by micro-habitat (domestic and peridomestic). The level of genetic structuring of Lu. intermedia population from each ecologic region is distinct and may reflect association or independence between the domestic and the peridomestic habitats in rural and periurban areas, respectively, both reflecting distinct characteristics of the transmission cycle of ACL.

Peridomestic colonization of Triatoma longipennis (Hemiptera, Reduviidae) and Triatoma barberi (Hemiptera, Reduviidae) in a rural community with active transmission of Trypanosoma cruzi in jalisco state, Mexico

Infestation of peridomiciles is likely a major risk factor for Chagas disease transmission in Jalisco state, Mexico. An entomological and serological survey of a typical village was conducted between July and September 2003. The peridomestic areas of 100 dwellings were visited and triatomines were searched manually in 369 potential sites. A total of 1821 Triatoma longipennis (93.2%) or Triatoma barberi was captured. Both species frequently occurred in sympatry. The infestation index was 60% for T. longipennis and 16% for T. barberi. T. longipennis occurred throughout the village. Colonization indices were high for T. longipennis (93%) and T. barberi (75%), suggesting that both species have adapted to peridomestic habitats. The bug population size was larger for T. longipennis than for T. barberi. Five very large colonies of T. longipennis were recorded whereas only 1 or 2 bugs were observed in 38% of the positive sites, which suggests intense dispersal activity. Both species exhibited high infection prevalence with Trypanosoma cruzi (46%). Only T. cruzi lineage I was detected. Human seroprevalence was 1.8%. This study serves as an entomological overview of peridomiciliar triatomine colonization in a Mexican village and highlights the current risk of Chagas disease transmission.

Effect of Abiotic Factors on Seasonal Population Dynamics of &lt;I&gt;Lutzomyia longipalpis&lt;/I&gt; (Diptera: Psychodidae) in Northeastern Brazil

The resurgence of visceral leishmaniasis in Brazil increases the need for studies to elucidate the spatial and temporal dynamics of Lutzomyia longipalpis (Lutz and Neiva) (Diptera: Psychodidae), the vector of Leishmania infantum, the causative agent of visceral leishmaniasis in Brazil. Sand flies were captured in peridomestic habitats biweekly for 3 yr. Cross-correlation tests and spectral analysis were used to analyze the simultaneous and lag-time correlations between Lu. longipalpis population densities and abiotic factors of temperature, relative humidity, wind velocity, and rainfall. Distinct seasonal patterns were observed for males and females, with intervals of 6 mo between population peaks for males and 12 mo for females. Peak female population densities lagged 3 mo behind the maximum annual temperature. Female population density was negatively correlated with relative humidity. An increase in average wind velocity was followed by a decrease in the number of females for 2 wk. Understanding the relationship between the seasonal population dynamics of Lu. longipalpis and abiotic factors will contribute to the design of better control measures to decrease transmission of L. infantum and consequently the incidence of leishmaniasis.

Long-term reduction of Trypanosoma cruzi infection in sylvatic mammals following deforestation and sustained vector surveillance in northwestern Argentina

Long-term variations in the dynamics and intensity of sylvatic transmission of Trypanosoma cruzi were investigated around eight rural villages in the semiarid Argentine Chaco in 2002–2004 and compared to data collected locally in 1984–1991. Of 501 wild mammals from 13 identified species examined by xenodiagnosis, only 3 (7.9%) of 38 Didelphis albiventris opossums and 1 (1.1%) of 91 Conepatus chinga skunks were infected by T. cruzi. The period prevalence in opossums was four-fold lower in 2002–2004 than in 1984–1991 (32–36%). The infection prevalence of skunks also decreased five-fold from 4.1–5.6% in 1984–1991 to 1.1% in 2002–2004. Infection in opossums increased with age and from summer to spring in both study periods. The force of infection per 100 opossum-months after weaning declined more than six-fold from 8.2 in 1988–1991 to 1.2 in 2002–2004. Opossums were mainly infected by T. cruzi lineage I and secondarily by lineage IId in 1984–1991, and only by T. cruzi I in 2002–2004; skunks were infected by T. cruzi IId in 1984–1991 and by IIc in 2002–2004. The striking decline of T. cruzi infection in opossums and skunks occurred in parallel to community-wide insecticide spraying followed by selective sprays leading to very low densities of infected Triatoma infestans in domestic and peridomestic habitats since 1992; to massive deforestation around one of the villages or selective extraction of older trees, and apparent reductions in opossum abundance jointly with increases in foxes and skunks. These factors may underlie the dramatic decrease of T. cruzi infection in wild reservoir hosts.

Host-feeding patterns of Aedes albopictus (Diptera: Culicidae) in relation to availability of human and domestic animals in suburban landscapes of central North Carolina.

Aedes albopictus (Skuse) (Diptera: Culicidae) is a major nuisance mosquito and a potential arbovirus vector. The host-feeding patterns of Ae. albopictus were investigated during the 2002 and 2003 mosquito seasons in suburban neighborhoods in Wake County, Raleigh, NC. Hosts of blood-fed Ae. albopictus (n = 1,094) were identified with an indirect enzyme-linked immunosorbent assay, by using antisera made in New Zealand White rabbits to the sera of animals that would commonly occur in peridomestic habitats. Ae. albopictus fed predominantly on mammalian hosts (83%). Common mammalian hosts included humans (24%), cats (21%), and dogs (14%). However, a notable proportion (7%) of bloodmeals also was taken from avian hosts. Some bloodmeals taken from birds were identified to species by a polymerase chain reaction-heteroduplex assay (PCR-HDA). Ae. albopictus fed predominantly on chickens and a northern cardinal. PCR-HDA failed to produce detectable products for 29 (58%) of 50 bloodmeals for which DNA had been amplified, indicating that these mosquitoes took mixed bloodmeals from avian and nonavian hosts. Ae. albopictus preference for humans, dogs, and cats was determined by calculating host-feeding indices for the three host pairs based on the proportion of host specific blood-fed mosquitoes collected in relation to the number of specific hosts per residence as established by a door-to-door survey conducted in 2003. Estimates of the average amount of time that residents and their pets (cats and dogs) spent out of doors were obtained. Host-feeding indices based only on host abundance indicated that Ae. albopictus was more likely to feed on domestic animals. However, when feeding indices were time-weighted, Ae. albopictus fed preferentially upon humans. Ae. albopictus blood feeding on humans was investigated using a STR/PCR-DNA profiling technique that involved amplification of three short tandem repeats loci. Of 40 human bloodmeals, 32 (80%) were from a single human, whereas eight (20%) were multiple bloodmeals taken from more than one human host. We conclude that the blood-feeding preference of Ae. albopictus for mammals will limit acquisition of arboviruses by this species from infected avian amplification hosts. This feeding preference likely limits the vector potential of Ae. albopictus for North American arboviruses.

Isolation ofLeishmania (Viannia) braziliensisfromLutzomyia spinicrassa(species groupVerrucarum) Morales Osorno Mesa, Osorno &amp; Hoyos 1969, in the Venezuelan Andean Region

Natural infection with Leishmania spp. in phlebotomine sandflies was searched for during a longitudinal study carried out from July 1997 to July 1998 in the village Catarnica, Municipality Independencia, Táchira State. This hamlet is an old endemic focus of cutaneous leishmaniasis in the Venezuelan Andean region, which lies close to the Colombian border at 1,300 m a.s.l., in an agricultural area mainly used for cultivating coffee. Phlebotomine sandflies were collected using Shannon traps placed in the peridomestic habitat from 19:00 to 21:00 hs. Males were stored in alcohol 70 % while females were kept in Nunc vials with 10 % DMSO and cryopreserved in liquid nitrogen for subsequent dissection and identification. The most abundant anthropophilic species was Lutzomyia spinicrassa with 3,032 males and 4,290 females (85.4%). Among 1,633 (38%) females of Lu. spinicrassa dissected, 26 11.6%) were infected with promastigotes, while no natural infection was found in 209 females of other species. The flagellates were identified as Leishmania braziliensis braziliensis using PCR with species specific primers derived from nuclear DNA and hybridization using species specific probe labelled with digoxigenin. This parasite had been previously isolated from patients with cutaneous leishmaniasis from the same area. These results show Lu. spinicrassa as a new proven vector of Leishmania braziliensis in the Andean region of Venezuela.

Importance of Socioeconomic Status and Tree Holes in Distribution of &lt;I&gt;Aedes&lt;/I&gt; Mosquitoes (Diptera: Culicidae) in Jodhpur, Rajasthan, India

Immature Aedes mosquitoes were found in domestic, peridomestic, and tree hole habitats within three socioeconomic strata of Jodhpur, a city within an arid area of Rajasthan, India, endemic for dengue. Peridomestic habitats served as a persistent source of Aedes vectors, especially those used for watering cows for religious reasons that were located within high socioeconomic areas. Domestic (indoor) containers within low socioeconomic strata showed a higher container index (27.0%) than periurban areas with cattle sheds (14.3%) or high socioeconomic areas (18.1%). Mosquitoes were collected in tree holes at zoos and gardens supporting several species of monkeys. Six of 67 Aedes albopictus Skuse reared from immatures collected in tree holes tested positive for dengue antigen acquired through vertical transmission, possibly indicating a persistence mechanism for dengue virus within an urban environment.

Importance of Socioeconomic Status and Tree Holes in Distribution of Aedes Mosquitoes (Diptera: Culicidae) in Jodhpur, Rajasthan, India

Abstract Immature Aedes mosquitoes were found in domestic, peridomestic, and tree hole habitats within three socioeconomic strata of Jodhpur, a city within an arid area of Rajasthan, India, endemic for dengue. Peridomestic habitats served as a persistent source of Aedes vectors, especially those used for watering cows for religious reasons that were located within high socioeconomic areas. Domestic (indoor) containers within low socioeconomic strata showed a higher container index (27.0%) than periurban areas with cattle sheds (14.3%) or high socioeconomic areas (18.1%). Mosquitoes were collected in tree holes at zoos and gardens supporting several species of monkeys. Six of 67 Aedes albopictus Skuse reared from immatures collected in tree holes tested positive for dengue antigen acquired through vertical transmission, possibly indicating a persistence mechanism for dengue virus within an urban environment.

Genetic structure of Triatoma venosa (Hemiptera: Reduviidae): molecular and morphometric evidence

Triatoma venosa presents a restricted geographical distribution in America and is considered as a secondary vector of Chagas disease in Colombia and Ecuador. A total of 120 adult insects were collected in domestic and peridomestic habitats in an endemic area of the department of Boyacá, Colombia, in order to determine their genetic structure through morphometric and molecular techniques. The head and wings of each specimen were used for the analyses of size, shape, and sexual dimorphism. A significant sexual dimorphism was found, although no differences in size among the studied groups were detected. Differences were found in the analyzed structures except for male heads. DNA was extracted from the legs in order to carry out the internal transcriber space-2 (ITS-2) amplification and the randon amplified polymorphic DNA (RAPD) analyses. Length polymorphisms were not detected in the ITS-2. Fst and Nm values were estimated (0.047 and 3.4, respectively). The high genetic flow found among the insects captured in the domicile and peridomiciliary environment does not permit a genetic differentiation, thus establishing the peridomicile as an important place for epidemiological surveillance.

Entomological Investigations in Chichaoua: An Emerging Epidemic Focus of Cutaneous Leishmaniasis in Morocco

Cutaneous leishmaniasis due to Leishmania tropica Wright seems to be an emerging disease in Chichaoua, a province located in southwestern Morocco. In this study, sand flies (Diptera: Psychodidae) were collected from 12 stations. Sticky traps were placed in domestic, peridomestic, and sylvatic sites. In total, 3,787 specimens consisting of 10 species (seven Phlebotomus and three Sergentomiya) were identified. Phlebotomus perniciosus Newstead, the predominant species, was abundant, especially in mountainous areas. Phlebotomus sergenti Parrot (12%) was found in all studied villages where it was associated with domestic and peridomestic habitats. On the basis of its abundance, distribution, and notable anthropophily, P. sergenti, a proven vector of L. tropica elsewhere, is considered the cutaneous leishmaniasis vector in this emerging focus.

Detection of entomopathogenic fungi in peridomestic triatomine-infested areas in central Brazil and fungal activity against Triatoma infestans (Klug) (Hemiptera: Reduviidae)

From 148 substrate samples collected in peridomestic triatomine-infested habitats of 24 farms in Central Brazil, 31 isolates of Metarhizium anisopliae (Metsch.) Sorok. and 15 isolates of Beauveria bassiana (Bals.) Vuill. were obtained. Most of the isolates were found in substrates that consisted of soil mixed with animal feces or soil only in areas of trees where poultry roost and pig houses. Fungi were detected with an insect bait method using Triatoma infestans (Klug), and combined in vitro and in vivo techniques with modified Chase medium and T. infestans. All isolates were highly virulent to T. infestans third instar nymphs at a relative humidity > 98% and temperature of 25 ± 0.5°C. However, activity against nymphs was reduced at 75% relative humidity. Results underline the potential of B. bassiana and M. anisopliae as agents for biological control of vectors of Chagas disease. Both species occur naturally in peridomestic habitats of triatomines in Central Brazil and may contribute to control these vectors and to reduce the risk of reinfestation of houses after eliminating domestic vector species.

Bionomics of phlebotomine sandflies in the Galilee focus of cutaneous leishmaniasis in northern Israel

The bionomics of phlebotomine sandflies (Diptera: Psychodidae) were studied for three years (2001-2003) in the Galilee focus of cutaneous leishmaniasis in northern Israel, where the causative Leishmania tropica (Kinetoplastida: Trypanosomatidae) is transmitted by Phlebotomus (Adlerius) arabicus Theodor and Phlebotomus (Paraphlebotomus) sergenti Parrot, comprising 22% and 8%, respectively, of the local sandfly fauna sampled by light traps. The predominant species overall was Phlebotomus (Larroussius) tobbi Adler & Theodor (51%) with lesser numbers of Phlebotomus (Adlerius) simici Theodor (11%), Phlebotomus (Larroussius) syriacus Adler & Theodor (5%), Phlebotomus (Larroussius) perfiliewi Perfil'ev (3%) and Phlebotomus (Phlebotomus) papatasi Scopoli (0.05%). Sandfly adult populations were prevalent from April to November and peaked between June and August, being more abundant through the summer in irrigated habitats, such as gardens and orchards, than in open grassland. Of the two cutaneous leishmaniasis vectors, P. sergenti preferred boulder mounds located at the outskirts of settlements, whereas P. arabicus was more abundant overall and near houses in particular. Females of all these sandfly species displayed a peak of activity after sunset (20.00-22.00 hours), whereas activity of males persisted longer through the night. Another slight increase in activity was noted before dawn (02.00-04.00 hours). Phlebotomus arabicus appears to be the main vector of L. tropica in the Galilee focus, due to its denser populations, more endophily and preference for peridomestic habitats than shown by P. sergenti in northern Israel.