Alterations were studied in 857 samples of skeletal muscle from mice experimentally infected with Trypanosoma cruzi and Schistosoma mansoni. In some of the animals the T. cruzi infection was followed up to 126 days. The presence of S. mansoni infection had no apparent effect on the picture of the “polymyositis” caused by T. cruzi infection. There was an apparent relationship between the percentage of damaged muscles and the number of trypanosomes inoculated. Schistosome infection that was not associated with trypanosomiasis caused minor muscle lesions in only 5 of the 107 muscles examined. These consisted of intramuscular panarteritis and perivascular lymphocytic infiltration in the perimysium.
The rates of spontaneous death in the several experimental groups suggested that T. cruzi infection may have had a protective effect against S. mansoni infection.
Laboratory of Neuropathology and Department of Pathologic Anatomy of the University of Recife Medical School.
Instituto Nacional de Endemias Rurais, Centro de Pesquisas Aggeu Magalhães, Caixa Postal, 459, Recife (Brazil). E. Coutinho-Abath is a research fellow of the National Research Council of Brazil.