Carlos Chagas in 1932. Carlos Chagas (1879-1934) was a Brazilian sanitary physician, scientist and bacteriologist who worked as a clinician and researcher. He discovered Chagas disease, also called American trypanosomiasis in 1909, while working at the Oswaldo Cruz Institute in Rio de Janeiro. Working in primitive conditions, Chagas described in detail a previously unknown infectious disease: its pathogen, vector (Triatominae), host, clinical manifestations and epidemiology. Chagas was also the first to discover and illustrate the parasitic fungal genus Pneumocystis, later infamous for being linked to PCP (Pneumocystis pneumonia in AIDS patients).