A Cluster ofPneumocystis cariniiPneumonia in Adults without Predisposing Illnesses

Abstract

PNEUMOCYSTIS CARINII pneumonia is the most common infection complicating the acquired immunodeficiency syndrome (AIDS),^{1 , 2} but before 1981 it was a rare condition. P. carinii pneumonia was first reported in the United States in 1955,³ and only 107 cases were reported during the subsequent decade.⁴ Before the AIDS epidemic, more than 99 percent of patients with P. carinii pneumonia had a predisposing condition, such as lymphoma, leukemia, organ transplantation, or a disorder treated with corticosteroids or cytotoxic drugs.^{4 , 5} Reports of P. carinii pneumonia in nonimmunocompromised adults are extremely rare.^{6 7 8 9 10} Serologic but not histopathological evidence of latent subclinical P. carinii infection has been observed in two thirds of normal immunocompetent children by the age of four years,¹¹ and it has been implicated in pneumonia in normal neonates.¹² Clusters were first observed in debilitated children in orphanages after World War II. Over the past 25 years, four clusters in adults and children have occurred in transplant centers and cancer hospitals; in each instance the infected patients were immunocompromised.^{13 14 15 16}