Myocardial involvement in Cavia porcellus naturally infected with Trypanosoma cruzi.

This paper describes the myocardial involvement analyzed by histopathological examination in rural Cavia porcellus during natural T. cruzi infection. Four Cavia porcellus of both sexes were bred in a house free of Triatoma infestans. In contrast, four animals were born and lived in a rural yard colonized by T. infestans. Autopsies were performed at 6-9 months of age, in animals weighing 550 to 750 grams. The naturally infected Cavia porcellus presented moderate and severe lymphocyte and plasmocyte infiltrates, focally or diffusedly distributed. Replacement of myocytes both in atria and ventricles was often found and consisted of loose or dense connective tissue infiltration. Regarding the conducting system, polymorphonuclear cell infiltrates were observed in the A-V node and in the left bundle branch. Uninfected Cavia porcellus did not show these lesions. Typical chagasic cysts were not found in the naturally infected Cavia porcellus hearts. Parasitism was not observed in the skeletal muscles. It is concluded that naturally infected Cavia porcellus develop consistent lesions similar to those described in human chronic chagasic myocardiopathy. The high susceptibility of naturally infected Cavia porcellus must be taken into account when these animals are used in studies regarding chronic chagasic myocardiopathy.