Young dogs were inoculated with T. cruzi Y and CL strains either by intraperitoneal route with 107 blood forms or by ocular route with 2 x 10³ vector-derived trypomastigotes. With both inocula the patterns of parasitemia were significantly different, confirming data previously obtained in experimentally infected mice and rabbits. CL strain induced a gradual ascencional parasitemia whereas with Y the parasitemia was either subpatent or the number of parasites was very low, rapidly declining. Although myocarditis was present in most animals regardless of the strain used, the inflammatory process was established earlier with the Ystrain. The severity of the myocarditis was not related to parasitemia and in some animals in which parasites could only be detected by xenodiagnosis the lesions were comparable to those detected in animals with high number of blood forms. In a similar way, no correlation was established between tissue parasitism and myocardium inflammatory lesions. Thus, the heart tissue damage in the acute phase was not apparently influenced by the differences inthe course of infection, suggesting a participation of immunological mechanisms even at this early stage of infection.
Trypanosoma cruzi; Y and CL strains; Dog's experimental myocarditis