Are genotypes of Trypanosoma cruzi involved in the challenge of chagasic cardiomyopathy?

Myocardial damage in Chagas' disease differs, depending on the particular Trypanosoma cruzi stock. It is reasonable to expect that the extent of phylogenetic divergence between lineages will have an impact on the biological properties of the parasite. The aim of the present work was to evaluate this impact on the cardiac damage produced by this protozoan. Heart histopathologic lesions were studied in mice infected with 15 cloned stocks of T. cruzi of various origins pertaining to 3 major clones or genotypes (19, 20, and 39) that share 3 different profiles for a given set of genetic markers. Sets of mice were infected intraperitoneally with 10⁶ blood trypomastigotes of each of the T. cruzi clones. The macroscopy study showed a cardiac index (CI) higher than 0.6 (cardiomegaly) in 5 of the 15 stocks studied (33.33%). Inflammatory infiltrates appeared in stocks pertaining to the three genotypes studied without relation to the genetic pattern. Pseudocysts were present at higher levels (83%) in stocks pertaining to genotype 39. A lower rate could be seen in stocks pertaining to genotype 19 (50%). Only one stock pertaining to genotype 20 presented myocardial parasites (20%). Hearts were also studied for lesions in the different cardiac chambers. Inflammatory foci as well as pseudocysts appeared mainly in ventricles, with the left ventricle sharing the highest percentage of pathologic findings. In summary, in spite of the similar inflammatory pattern demonstrated for all stocks studied, the parasite's presence seemed to be related to the genotype of reference, but no relation could be demonstrated with the genetic distances. Received: 4 June 1997 / Accepted: 17 September 1997