ABSTRACT
Pneumocystis carinii was first described in 1909 by Chagas in the lungs of guinea pigs during his studies of experimental American trypanosomiasis (1). He thought the organism was a variant in the sexual life cycle of Trypanosoma cruzi. One year later, Carini found the organism in trypanosome-infected rats (2). The Delanöes then found identical forms in the lungs of rats that had not been infected with trypanosomes; they clearly established that these organisms represented a new genus and species and assigned the name Pneumocystis carinii in honor of Dr. Carini (3,4).
