This is the presentation of data obtained by a study carried out in central Brazil, where the biogeographical characteristics include the "cerrados" (savannah), ample strips of transitional vegetation, and forests. These include the Atlantic tropical forest and the larger forested areas. From 1975 to 1980, a total of 3,160 bugs collected in domiciliar environments were examined to discover the blood feeding habits and the natural infection by Trypanosoma of the cruzi type. Methods were the same as those described in a previous paper. In order of frequency, the species found were: Triatoma infestans (43.5%), T. sordida (33.0%) and Panstrongylus megistus (23.5%), and some other rare ones. Blood was detected in 35.9% and the infection rate was 2.2% of the total specimens examined. Feeding mobility was observed, and the general blood containing rates were 54.0% from birds and 30.0% from humans. High evel of anthropophily was observed for T. infestans, and good degree of ornitophily was detected for T. sordida. For P. megistus considerable ornitophily was found too, but with good levels from mammal hosts. The presence of human blood in specimens collected in peridomiciliar dwelling places indicated frequent spacial morbility, specially for P. megistus and T. sordida. Geographical distribution confirmed the autochthonous pattern of T. sordida in the "cerrado" and of P. megistus in the Atlantic tropical forest. They become invasive to other biogeographical system from these regions. T. infestans showed invasive character for both areas, as a results of human influence. Results permit the conclusion that, in the regional epidemiological transmission of South American trypanosomiasis, T. infestans play the most important role, followed by P. megistus. Depending on several factors, T. sordida may become a potential risk for infestation dwellings. Routine control through the application of domiciliary chemicals will break transmission. However, at least in the peridomiciliary environment, reinfestation will continue mainly by P. megistus and T. sordida. This will be due to natural foci supplied by the human environment, demanding greater efforts in epidemiological surveillance and in its increased efficiency by research development.
Trypanosomiasis, South American; Triatominae; Triatominae; Triatominae; Triatominae