Animal reservoirs for Trypanosoma cruzi infection in an endemic area in Paraguay.

Animal reservoirs for Trypanosoma cruzi infection were investigated in 5 communities in the Department of San Pedro, currently one of Paraguay's most highly endemic areas. A total of 112 domestic animals (37 cattle, 2 horses, 1 ass, 20 pigs, 44 dogs and 8 cats) and 4 wild animals (1 white-eared opossum, 2 yellow armadillos and 1 common long-nosed armadillo) were examined for blood. Although no trypomastigotes were found by 2 direct observation methods, the microhaematocrit and Giemsa stained thick and thin smears methods, several forms of trypanosoma flagellates morphologically identical to T. cruzi were detected in the liver infusion tryptose (LIT) medium from a single sample taken from a yellow armadillo, Euphractus sexicintus. When serum samples of all the animals were examined for antibody to T. cruzi by direct agglutination (DA) test, 3 cattle, 2 pigs, 16 dogs and 3 cats had positive titers (1:32 or greater), but no wild animals showed positive reactions. T. cruzi was not found by culture nor microscopic examination of samples from any of the seropositive animals. However, domestic animals such as cattle, pigs, dogs and cats which were found to be seropositive in this study, possibly act as an animal reservoir in this endemic area as well as armadillos in which T. cruzi was observed.