SYLVATIC TRIATOMINES (HEMIPTERA, REDUVIIDAE) IN BOLIVIA - TRENDS TOWARD DOMESTICITY AND POSSIBLE INFECTION WITH TRYPANOSOMA-CRUZI (KINETOPLASTIDA, TRYPANOSOMATIDAE)

The risk of domestic transmission of Trypanosoma cruzi (Chagas) by syl vatic triatomines was assessed in an isolated area of the subandean re gion of Bolivia. None of the 390 residents examined had serological ev idence of infection. Two sylvatic triatomine species, Eratyrus mucrona tus (Stal) and Triatoma sordida (Stal), were found in houses and in pe ridomestic structures. The collection of nymphal instars of both speci es from some houses indicated possible domesticity. Microscopic examin ation 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 pr esence of T. cruzi DNA in 19.1 and 12.5% of E. mucronatus and T. sordi da, respectively. These 16 PCR-positive samples were hybridized with 2 T. cruzi-specific probes known from the domestic cycle in Bolivia (cl ones 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 obse rved with these probes in 8 E. mucronatus and 1 T. sordida samples tha t showed an amplified band by PCR. These data indicated that T. cruzi clones, genetically unrelated to clones 20 and 30, also were circulati ng in this area. Based on these results, the 2 sylvatic triatomine spe cies encountered in Apolo should not be overlooked as possible local v ectors of T. cruzi.