Sylvatic Triatomines (Hemiptera: Reduviidae) in Bolivia: Trends Toward Domesticity and Possible Infection with Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae)

Abstract

The risk of domestic transmission of Trypanosoma cruzi (Chagas) by sylvatic triatomines was assessed in an isolated area of the subandean region of Bolivia. None of the 390 residents examined had serological evidence of infection. Two sylvatic triatomine species, Eratyrus mucronatus (Stål) and Triatoma sordida (Stål), were found in houses and in peridomestic structures. The collection of nymphal instars of both species from some houses indicated possible domesticity. Microscopic examination of feces from 92 insects showed no parasites, and cultures from the guts of 30 insects were negative. Nevertheless, a polymerase chain reaction (PCR) test performed on the same fecal samples showed the presence of T. cruzi DNA in 19.1 and 12.5% of E. mucronatus and T. sordida, respectively. These 16 PCR-positive samples were hybridized with 2 T. cruzi-specific probes known from the domestic cycle in Bolivia (clones 20 and 39). At least 1 of these clones was identified in 7 bugs (5 E. mucronatus and 2 T. sordida). Moreover, no hybridization was observed with these probes in S E. mucronatus and 1 T. sordida samples that showed an amplified band by PCR. These data indicated that T. cruzi clones, genetically unrelated to clones 20 and 39, also were circulating in this area. Based on these results, the 2 sylvatic triatomine species encountered in Apolo should not be overlooked as possible local vectors of T. cruzi.

Wild Triatoma infestans, a potential threat that needs to be monitored

“…There are increasing reports of wild triatomine species invading human dwellings in areas where domestic vector populations have been targeted by chemical control interventions. In certain cases, the initial phenomenon of the intrusion of adult bugs into households may continue until the establishment of domestic breeding colonies (Noireau et al 1994(Noireau et al , 1995. Why would wild T. infestans be excluded from such a process even though this species has successfully adapted to domestic environments in the past?…”

Epidemiology of Chagas disease in Ecuador. A brief review

“…Other species present in Ecuador and potentially involved in T. cruzi transmission are T. venosa, found to breed inside houses in some areas of Colombia (D'Alessandro & Barreto 1985), Eraturys mucronatus, a species able to invade and colonise human environments (Lent & Wygodzinsky 1979, D'Alessandro & Barreto 1985, Noireau et al 1995 and P. chinai (Lent & Wygodzinsky 1979, Defranc 1982, Reyes 1992.…”

Attraction of Chagas disease vectors (Triatominae) to artificial light sources in the canopy of primary Amazon rainforest

“…This is clearly of more importance for species capable of colonising human households, which has not been reported in our study area. However, P. geniculatus can colonise peridomestic pigsties in Amazonia (Valente et al 1998), and Eratyrus mucronatus, P. geniculatus, P. rufotuberculatus and the P. lignarius population from the Marañón Valley, Peru (formerly known as P. herreri) have all been reported to breed within houses in other biomes (Barrett 1991, Noireau et al 1995, Wolff & Castillo 2000, AbadFranch et al 2001, Cuba Cuba et al 2002.…”