Four wild strains of T. cruzi were studied for this paper: M226 isolated from Calomys callosus (Rodentia) and R52, R64, and R65 from Didelphis albiventris (Marsupialia). The animals were captured in the county of Formosa in the State of Goias. trypanosome strains were studied in 40 Swiss mice and in laboratory stock of C. callosus. The following aspects were focused: parasitemia, prepatent period, lethality, and histopathologic reactions. Results indicated that these strains have low virulence for inoculated animals. Parasitemia was always low and regular for C. callosus. In mice, however, parasites were seen only in a few instances in the peripheral blood. The prepatent periods were 9.2 to 10.2 days for C. callosus and 12 to 48 days for mice. Lethality was 7.7% for C. callosus and 12% for mice. The parasites were found in the tissues of the inoculated animals in the proportions of 17.2% for C. callosus and 25% for mice. Tissue reaction in both rodent species showed that all the T. cruzi strains had strong affinity for skeletal or cardiac muscle.
Trypanosoma cruzi; Animals, laboratory