Pathologic features of dogs inoculated with North American Trypanosoma cruzi isolates.

Twenty-three clinically normal Beagles were inoculated with North American Trypanosoma cruzi isolates from an opossum (Tc-O), an armadillo (Tc-A), or a dog (Tc-D). The dogs were grouped according to the clinical outcome of inoculation. Group 1 consisted of 7 dogs inoculated with Tc-O or Tc-A that died or were euthanatized during acute stages of disease. Group 2 consisted of 5 dogs inoculated with Tc-O or Tc-A, that also developed acute disease, but survived to develop chronic disease. Group 3 consisted of 7 dogs inoculated with Tc-D neither developed acute nor chronic disease. Group 4 consisted of 4 dogs and served as noninoculated controls. In group 1, the gross lesions were diffusely pale myocardiums with right ventricular enlargement, hepatomegaly, and a moderate amount of modified transudate in the abdominal cavity. Severe diffuse granulomatous myocarditis with large numbers of pseudocysts and minimal fibrosis characterized the tissues from all cardiac chambers and septum. The lesions were most severe in the right atrium and ventricle. Mild multifocal myositis and pseudocysts were observed in skeletal muscles and smooth muscles of the urinary bladder and small intestine. Multifocal encephalitis and pseudocysts were in the cerebral cortex, cerebellum, and brain stem. In group 2, the gross lesions were biventricular enlargement and thinning of the ventricular free walls. The right ventricle contained the most severe microscopic changes. There were mild multifocal interstitial lymphohistocytic cellular infiltrates, perivasculitis, and marked fibrosis in all areas of the myocardium. Mild myositis and multifocal encephalitis were seen in the skeletal muscles and brains. Pseudocysts were not observed in any tissues.(ABSTRACT TRUNCATED AT 250 WORDS)