HISTOPATHOLOGICAL STUDY OF EXPERIMENTAL AND NATURAL INFECTIONS BY TRYPANOSOMA-CRUZI IN DIDELPHIS-MARSUPIALIS

Didelphis marsupialis, the most important sylvatic reservoir of Trypan osoma cruzi, can also maintain in their anal scent glands the multipli cative forms only described in the intestinal tract of triatomine bugs . A study of 21 experimentally and 10 naturally, infected opossums wit h T. cruzi was undertaken in order to establish the histopathological pattern under different conditions. Our results showed that the inflam mation was predominantly lymphomacrophagic and more severe in the natu rally infected animals but never as intense as those described in Chag as' disease or in other animal models. The parasitism in both groups w as always mild with very scarce amastigote nests in the tissues. In th e experimentally infected animals, the inflammation was directly, rela ted to the presence of amastigotes nests. Four 24 days-old animals, st ill in embryonic stage, showed multiple amastigotes nests and moderate inflammatory reactions, but even so they survived longer and presente d less severe lesions than experimentally infected adult mice. Parasit es were found in smooth, cardiac and/or predominantly striated muscles , as well as in nerve cells. Differing from the experimentally infecte d opossums parasitism in the naturally infected animals predominated i n the heart, esophagus and stomach. Parasitism of the scent glands did not affect the histopathological pattern observed in extraglandular t issues.