INTERRELATION OF SYLVATIC AND DOMESTIC TRANSMISSION OF TRYPANOSOMA-CRUZI IN AREAS WITH AND WITHOUT DOMESTIC VECTORIAL TRANSMISSION IN MINAS-GERAIS, BRAZIL

During the period 1980-1986, we captured triatomine bugs and mammalian reservoir hosts from sylvatic and domestic situations in different mu nicipalities of the State of Minas Gerais. Trypanosoma cruzi was isola ted from captured bugs, mammals and patients. After cultivation in LIT medium, the electrophoretic enzyme profiles were determined. We obtai ned a total of 32 parasite isolates from regions with active domestic transmission, and 24 isolates from areas under control. For the first areas the results suggest introduction of T. cruzi from sylvatic habit ats, through incursion of infected opossums and/or sylvatic T. sordida , which appears to have given rise to at least one acute human infecti on. Of particular interest is the finding of sylvatic opossums and a T . sordida nymph infected with ZB, that could indicate return of parasi tes from chronic human infections to sylvatic transmission cycles. For the areas under control we also interpret the results as interaction between sylvatic and domestic cycles of transmission, here through the invasion of houses by bugs carrying the Z1 zymodeme from the sylvatic environment. The Multivariate Correspondence Analysis gives a spatial description between the different parasite isolates and confirms the existence of a bridge in the opposite direction in the region with act ive vectorial transmission including the exporting of Z2 through the p eridomestic environment into the sylvatic cycle. For the other areas t his bridge corresponds especially to Panstrongylus megistus, importing Z1 into the domestic environment