Environmental suitability for Lutzomyia (Nyssomyia) whitmani (Diptera: Psychodidae: Phlebotominae) and the occurrence of American cutaneous leishmaniasis in Brazil.

BACKGROUND: Leishmaniasis represents an important public health problem in Brazil. The continuous process of urbanization and expansion of human activities in forest areas impacts natural habitats, modifying the ecology of some species of Leishmania, as well as its vectors and reservoirs and, consequently, changes the epidemiological pattern that contributes to the expansion of American cutaneous leishmaniasis in Brazil. Here, we discuss Lutzomyia (Nyssomyia) whitmani, the main vector of ACL, transmitting two dermotropic Leishmania species including Leishmania (Viannia) braziliensis and Leishmania (V.) shawi. METHODS: We used the maximum entropy niche modelling approach (MaxEnt) to evaluate the environmental suitability of L. (N.) whitmani and the transmission of ACL in Brazil, in addition to designing models for a future scenario of climate change. MaxEnt was used under the "auto-features" mode and the default settings, with 100-fold repetition (bootstrap). The logistic output was used with higher values in the habitat suitability map, representing more favourable conditions for the occurrence of L. (N.) whitmani and human cases of ACL. RESULTS: Two models were developed: the Lutzomyia (N.) whitmani model (LWM) and the American cutaneous leishmaniasis model (ACLM). LWM identified the species "preferential habitat" included regions with moderate annual precipitation (AP) between 1000-1600 mm, intermediate vegetation density (NDVI) values, mean temperature of the coldest quarter (MTCQ), between 15-21 °C, and annual mean temperature (AMT), between 19-24 °C. ACLM indicates that ACL is strongly associated with areas of intermediate density vegetation, areas with AP between 800-1200 mm, MTCQ above 16 °C and AMT below 23 °C. CONCLUSIONS: The models generated for L. (N.) whitmani and ACL indicated a satisfactory predictive capacity. Future projections of LWM indicate an expansion of climatic suitability for L. (N.) whitmani for the northern and southern regions of Brazil. Future projections of ACL indicate the ongoing process of disease expansion in the face of the predicted climatic changes and reinforce the broad geographical expanse of this disease in Brazil. The models were able to identify that a continuous process of environmental degradation favours the establishment of L. (N.) whitmani and the occurrence of ACL by a strong association of the vector(s) and ACL to areas of intermediate vegetation cover density.

Leishmaniasis transmission in an ecotourism area: potential vectors in Ilha Grande, Rio de Janeiro State, Brazil.

BACKGROUND: The south coast of Rio de Janeiro State, in Brazil, is endemic for cutaneous and visceral leishmaniases and is frequently visited by tourists from different parts of the world. Since the complex epidemiology of leishmaniases demands local studies, the goal of this study was to investigate the phlebotomine sand fly fauna and leishmaniases transmission in Ilha Grande, an ecotourism area of Angra dos Reis municipality. METHODS: Sand fly fauna was sampled in three monitoring stations using HP light traps in domiciles, peridomiciles and forests. Species abundance was evaluated by the Index of Species Abundance. A Leishmania natural infection survey was done using multiplex PCR and dot blot hybridization. RESULTS: During 15 consecutive months of sand fly monitoring, 1093 specimens from 16 species were captured. The potential leishmaniases vectors found were Lutzomyia (Nyssomyia) intermedia, L. migonei, L. (N.) flaviscutellata, L. (Psychodopygus) ayrozai and L. (Lutzomyia) longipalpis. Five species were new records in Ilha Grande: L. (Sciopemyia) microps, L. termitophila, L. firmatoi, L. rupicola and L. (P.) ayrozai. Higher species richness was found inside forest areas, although potential leishmaniases vectors were present in deforested areas, peridomiciles and inside houses. Lutzomyia (N.) intermedia and L. migonei were the most abundant species. Females of L. migonei showed a high rate (10.3%) of natural infection by Leishmania (Viannia) sp., probably Leishmania (V.) braziliensis. CONCLUSIONS: The detection of leishmaniases transmission and potential vectors in Ilha Grande is of public health concern, especially because tourists are frequently visiting the island. Besides reinforcing the epidemiological importance of L. (N.) intermedia in Rio de Janeiro State, the role of L. migonei in cutaneous leishmaniasis transmission is highlighted with its high rate of Leishmania natural infection. The finding of L. (L.) longipalpis confirmed the human autochthonous case of visceral leishmaniasis from the island. The presence of L. (N.) flaviscutellata in peridomestic areas is also an important finding, since the species is involved in the transmission of diffuse cutaneous leishmaniasis. Health education practices directed to the local community and tourists are important control actions that can be taken in Ilha Grande to reduce the burden of leishmaniases.

Ecology of American cutaneous leishmaniasis in the state of Rio de Janeiro, Brazil.

A study of the sand fly fauna was carried out in the endemic area ofAmerican cutaneous leishmaniasis (ACL) in the Municipality of Mesquita, State of Rio de Janeiro, in an area where dwellings (with humans and dogs infected by Leishmania (Viannia) braziliensis) have been recently visited by sloths. Weekly captures were made during two consecutive years in two different sites (1 m and 600 m above sea level) and in three different habitats in each site (domestic, extra-domestic and sylvatic) using CDC light traps and Shannon traps. The following species were identified: Brumptomyia (Brumptomyia) guimaraesi, B. (B.) nitzulescui, Lutzomyia (Lutzomyia) longipalpis, L. migonei, L. serrana, L. (Psathyromyia) lutziana, L. barrettoi, L. (Nyssomyia) intermedia, L. (N.) whitmani, L. (Mycropygomyia) schireiberi, L. quinquefer, L. sallesi, L. (Psychodopygus) ayrozai, L. pascalei, L. (Pintomyia) bianchigalatiae and L. lanei. The collection of B. guimaraesi and B. nitzulescui species indicates the proximity of the study area to the sylvatic habitat. Two important suspected vectors of ACL were found: L. intermedia and L. migonei. L. longipalpis, a proven vector of American visceral leishmaniasis (AVL), was also found in this area. L. intermedia, the predominant sand fly species, was collected by both methods of capture and in the three different sites. It was observed biting man inside houses, but it was less anthropophilic in the sylvatic habitat. Our observations suggest that altitude does not influence the dispersion of L. intermedia population in the Municipality of Mesquita. The data indicate that L. intermedia remains as a putative vector of Leishmania (V.) braziliensis in this locality. An hypothesis of a sylvatic transmission cycle in the area and its correlation with the domestic cycle are discussed in the present paper.