Triatomine bugs in the State of Santa Cruz, Bolivia, and northeastern portions of Brazil, with special reference to their infection rate with Trypanosoma cruzi

The number and species of triatomine bugs collected in houses in the State of Santa Cruz, Bolivia, where Chagas disease infection from mothers to infants is frequently reported, and the infection rate of Trypanosoma cruz in bugs are shown in this study. The result was that large numbers of Triatoma infestans were collected indoors, their infection rate of T. cruzi is extremely high, an average of 80.5%; suggesting that the infection cycle of Chagas disease occurs indoors. In addition, because the T. cruzi-IgG antibody-positive rate for humans in this region is also high at 84.0%, residents are surmised to be in danger of constant infection. In contrast, there are almost no triatomine bugs in dwellings in the northeastern portion of Brazil where infection from mothers to infants has not been reported; triatomine bugs were found only in sheds for animals. However, these triatomine bugs are zoophilic (e.g., feeding on birds) and their infection rate with T. cruzi was extremely low, so the risk of Chagas disease is thought to be extremely low.