Eco-epidemiology of Chagas disease in northeastern Brazil: Triatoma brasiliensis, T. pseudomaculata and Rhodnius nasutus in the sylvatic, peridomestic and domestic environments

Abstract

An entomological survey was carried out in four rural localities situated in the state of Ceará, assessing Chagas disease seroprevalence in man, focusing on the presence of vectors in natural foci contiguous to the domestic and peridomestic environments. Fifty-three Triatoma brasiliensis, nine T. pseudomaculata and 71 Rhodnius nasutus were collected in their natural habitats as far as 10 m from the houses, and 663, 59 and 8 respectively were captured in peridomestic artificial structures, adjacent to the houses, including henhouses, pigpens, corrals, perches and piles of bricks, tiles and wood. Within the households, 37 T. brasiliensis, one specimen of T. pseudomaculata and one of R. nasutus were captured. Overall, Trypanosoma cruzi infection rates were 2.3% for T. brasiliensis and 11.3% for R. nasutus. Despite that the seroprevalence survey in man did not reveal positive results using two serological techniques, natural triatomine habitats are juxtaposed to man-made artificial ecotopes, resulting in overlapping habitats. The contiguity between natural ecotopes and human dwellings increases the interaction between vectors and humans, challenging continuous surveillance and vector control efforts.

On palms, bugs, and Chagas disease in the Americas

“…sordida and T. pseudomaculata were also detected (Sarquis et al, 2004(Sarquis et al, , 2012 Given the predominance of palms sampled on a single occasion, we did not 375 expect our Co. prunifera occupancy estimates to be very precise; at the same time, this 376 made us suspect that the uncorrected, naïve infestation index (26.5%, see Table 1) might 377 be particularly biased low for this palm species. We also note that only 36 palms were 378 sampled at sites not classified as Caatinga (i.e., along the Cerrado-Caatinga transition 379 and in patches of Atlantic forest surrounded by Caatinga); we therefore did not attempt 380 to estimate sub-regional effects for Co. prunifera, which is a typical Caatinga palm 381 (Henderson et al, 1995).…”

Molecular Identification of Food Sources in Triatomines in the Brazilian Northeast: Roles of Goats and Rodents in Chagas Disease Epidemiology

“…In the low Jaguaribe Valley, Ceará State, northeastern Brazil, native Chagas disease vectors, mainly Triatoma brasiliensis and Triatoma pseudomaculata, are responsible for maintaining the domestic and peridomestic Trypanosoma cruzi cycles, [1][2][3] being considered difficult to control in the region, because they keep foci in sylvatic ecotopes and frequently display high Trypanosoma cruzi natural infection. 3 Early approaches to explore the triatomine dietary habits have been based on immunological tests such as precipitin 4 and enzyme-linked immunosorbent assay (ELISA).…”

A Common Caatinga Cactus, Pilosocereus gounellei, is an Important Ecotope of Wild Triatoma brasiliensis Populations in the Jaguaribe Valley of Northeastern Brazil

“…23 Active dispersal of adult T. brasiliensis from either cacti or rocky outcrops can also directly contribute to dwelling infestation and re-infestation in some areas. 12,13,24 In conclusion, the observations we report open the way to solving one long-standing question about T. brasiliensis s.s. ecology, namely, the origin of re-infesting vectors in areas without rocky outcrops. Future work will aim at confirming our present data with further sampling, at studying vectorhost-parasite interactions, and at assessing the genetic relationships of wild (from cacti, rocks, and timber piles), peridomestic and domestic populations of T. brasiliensis by using highresolution molecular markers.…”

“…21,22 This model estimated mean bug density at approximately 4.3 (SE = 0.78) for an overall total abundance of about 187.9 T. brasiliensis in the 44 cacti we sampled, with an upper limit of the 95% confidence interval of 255.2. Previous surveys [12][13][14][15] have detected Trypanosoma cruzi infection in 17.4% (95% exact confidence interval 16.1-18.8%) of 2,982 T. brasiliensis specimens collected in the study region. Based on model estimates of bug-detection sensitivity (which, for the methods we used was low: mean = 0.15, SE = 0.02), on catch effort, and on the observed patterns of bug presence, our analyses suggest that most of the P. gounellei we sampled might have been infested: model-estimated infestation probability was 98.6% (95% confidence interval = 96.5-100%).…”

“…2,9-12 However, re-infestation of artificial structures is also commonplace in sedimentary lowlands where no such rocky outcrops exist; in addition, T. brasiliensis often occurs in wood piles near houses, [13][14][15] particularly when these are also occupied by rodents (Valença-Barbosa C, unpublished data). These observations led us to hypothesize that T. brasiliensis s.s. should be able to exploit alternative (i.e., non-rocky) ecotopes in the wild, possibly in association with rodents.…”