Effects of severe protein restriction in levels of parasitemia and in mortality of mice acutely infected with Trypanosoma cruzi.

Adult mice were submitted to different degrees of protein restriction for five weeks (4.75, 9.5, 14.25 and 19% of protein in isocaloric diets with normal content of mineral and vitamins), being subsequently infected with two strains of Trypanosoma cruzi: 10(5) trypomastigotes of Y strain or 10(4) trypomastigotes of CL strain. The same diet was maintained for all animals and the infection was followed up by evaluation of blood parasites, mortality and intensity of lesions in the heart and skeleton muscle. Only severe protein restriction (4.75%) induced decrease in resistance to the infection with both the Y and CL strains of T. cruzi, which resulted in higher parasitemia and mortality. The inflammatory lesions in heart and skeleton muscle were less extensive in groups with severe protein restriction despite the increased number of parasite in muscle cells. Depression of immune mechanisms could be responsible for the reduced resistance and reduced inflammatory reaction after T. cruzi infection in severely protein restricted animals.