Endemic Pneumocystis carinii in a marmoset colony

Retrospective examination of lungs from 441 marmoset necropsies conducted over a decade disclosed endemic pneumocystosis. Age distribution and colony residence time analysis suggest predisposition in the young and long-term residents. Only 2 cases were judged to have been of possible clinical significance on the basis of histopathological evaluation. Special stains, including PAS and methenamine silver were necessary to demonstrate many infections as the organisms were frequently widely scattered in small clusters. The marmoset may be a useful model for study of the human disease.