Infections of inbred mice with three Trypanosoma cruzi isolates from Louisiana mammals

Trypanosoma cruzi isolates from a dog (Tc-D), opossum (Tc-O), and an armadillo (Tc-A) from southern Louisiana were inoculated into 6 inbred mouse strains. None of the isolates produced fatal infections in the mouse strains tested. Parasitemias were quantified over 34 days and found to be similar in mouse strains infected with Tc-O and Tc-A. Parasitemias in Tc-D-infected mice were detectable only by blood culture. Pseudocyst numbers, inflammatory changes, and weight changes were quantified in CF1 mice infected with the 3 isolates. Tc-O- and Tc-A-infected CF1 mice were shown to be myotropic and produced comparable weight increases, pseudocyst numbers, and inflammatory changes in similar tissues. Tissues found to contain pseudocysts were muscles of the bladder, abdominal wall, thigh, heart, and diaphragm. Clinical signs of infection, pseudocyst numbers, and inflammatory changes were minimal in Tc-D-infected CF1 mice. Tissue tropism of this isolate was not determined. The in vivo infectivity characteristics of these isolates suggests that Tc-O and Tc-A are similar and differ markedly from Tc-D.