Abstract
In a population from an area endemic for Chagas' disease in Ecuador, cellmediated immune activity was assessed using delayed type hypersensitivity (DTH) reaction to PPD. Expression of DTH was significantly suppressed in individuals seropositive to Trypanosoma cruzi, and the suppression was markedly greater in the age group 10-39 years old than those over 40 years. The results show that cell-mediated immune response is apparently suppressed in patients with Chagas' disease, and tends to be restored in chronic stage. No defference was noted in the serum concentration of immunoglobulins between patients and controls.