title: A natural source of infection due to pneumocystis carinii.
mesh_terms: D000391:Air Microbiology; D000818:Animals; D006801:Humans; D011010:Pneumocystis; D011020:Pneumonia, Pneumocystis / Q000209:etiology* / Q000635:transmission; D051381:Rats; D012988:Soil Microbiology