Effects of Trypanosoma brucei and Babesia microti infections on the primary granulomatous reaction to Schistosoma eggs in mice.

Mouse infection with the blood protozoa Trypanosoma brucei suppressed significantly the frequency and intensity of the primary granulomatous inflammatory response to eggs of the blood flukes Schistosoma mansoni and S. bovis injected into the pulmonary microvasculature. In addition, the dynamics of the cellular infiltrate of the egg granuloma were strongly affected. It is suggested that the modulation of the granulomatous response is a result of impairment of the cell-mediated immunological responsiveness induced by T. brucei. Infection with Babesia microti did not induce similar effects on the granulomatous response.