Trypanosoma rangeli: increase in virulence with inocula of different origins in the experimental infection in mice.

We compared two murine models of Trypanosoma rangeli infection. The same inoculum dose and age-matched hosts were used in both cases. One group was infected with trypomastigotes obtained from passages in mice and the other, with trypomastigotes obtained from cell culture after a passage in mice. We observed that trypomastigotes obtained from the in vitro cellular infection showed increased virulence in experimental animals, with a 70% rate of death being noted in experimental mice instead of the lack of mortality seen when in vivo-derived parasites were used. The greatest levels of parasitemia and tissual lesions in the presence of the parasite also occurred when in vitro-derived parasites were used.