 Chagas named the pathogenic parasite as Trypanosoma cruzi and later that year as Schizotrypanum cruzi , both honoring Oswaldo Cruz , the noted Brazilian physician and epidemiologist who successfully fought epidemics of yellow fever , smallpox , and bubonic plague in Rio de Janeiro and other cities in the beginning of the 20th century . Chagas was also the first to unknowingly discover and illustrate the parasitic fungal genus Pneumocystis , later infamously linked to PCP ( Pneumocystis pneumonia in AIDS victims ) . Confusion between the two pathogens ' life @-@ cycles led him to briefly recognize his genus Schizotrypanum , but following the description of Pneumocystis by others as an independent genus , Chagas returned to the use of the name Trypanosoma cruzi . 
