One hundred and two blood serum samples from dogs referred to the Veterinary Teaching Hospital of Alfenas University, were submitted to the agarose immune diffusion and to the fast serum-agglutination tests addressed to find antibodies anti- Brucella canis and B. abortus, respectively. Five samples (4.9%) were positives for B. canis and none for B. abortus. This prevalence is considered by some as an alert for an epidemiologic and public healthy problems, considering the serious zoonotic aspect of canine brucellosis

One hundred and two blood serum samples from dogs referred to the Veterinary Teaching Hospital of Alfenas University, were submitted to the agarose immune diffusion and to the fast serum-agglutination tests addressed to find antibodies anti- Brucella canis and B. abortus, respectively. Five samples (4.9%) were positives for B. canis and none for B. abortus. This prevalence is considered by some as an alert for an epidemiologic and public healthy problems, considering the serious zoonotic aspect of canine brucellosis.

During the period 1980-1986, we captured triatomine bugs and mammalian reservoir hosts from sylvatic and domestic situations in different municipalities of the State of Minas Gerais. Trypanosoma cruzi was isolated from captured bugs, mammals and patients. After cultivation in LIT medium, the electrophoretic enzyme profiles were determined. We obtained 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 habitats, through incursion of infected opossums and/or sylvatic T. sordida, which appears to have given rise to at least one acute human infection. Of particular interest is the finding of sylvatic opossums and a T. sordida nymph infected with ZB, that could indicate return of parasites 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 active vectorial transmission including the exporting of Z2 through the peridomestic environment into the sylvatic cycle. For the other areas this bridge corresponds especially to Panstrongylus megistus, importing Z1 into the domestic environment.

A study was undertaken about T. sordida in the natural environment in two different regions of the state of Minas Gerais: Itapagipe (Triângulo), an area of cerrado modified by the formation of fields of pasture and agriculture, and Mato Verde (north) an area of transition between caatinga and cerrado with profound deforestation in the last years due to the expansion of cotton cultivation. In both regions the principal ecotopes identified were hollow trees and the bark of live or dead trees, where the occurrence of a food source is not frequent. In this environment, the triatomines utilize various food sources; opposums appear to represent an important source of infection. In the north of Minas, a greater concentration of reservoirs and vectors was observed than in the Triângulo which could explain the higher level of infection of the triatomines in the north. Close attention to the process of domiciliation of T. sordida in the north of Minas is recommended where an extensive intervention by man in the natural environment has occurred and where a rise in the population of triatomines in the peridomestic environment has been observed in recent years.