An unusual cluster of 11 patients with Pneumocystis carinii

pneumonia occurred in a 3-month period at Memorial Hospital, New York. Ten of the 11 patients had lymphoma or leukemia. In 7 patients, corticosteroid therapy was decreased or stopped shortly before Pneumocystis pneumonia was diagnosed. The pediatric patients had extensive contact in the outpatient department, and three of them had roomed together, suggesting the possibility of man to man transmission. Three of 4 adult patients with Hodgkin's disease and Pneumocystis pneumonia had the same physician. This physician had an indirect immunofluorescent titer of 1:16, as did an infectious disease resident involved in the care of 6 patients. Three of 9 patients tested showed indirect immunofluorescent titers of 1:16 or above, with rising or falling titers on serial specimens. Although definitive evidence of communicability was not established, patients with suspected or proved Pneumocystis pneumonia are now isolated in this hospital. ALTHOUGH SEVERAL EPIDEMICS of Pneumocystis carinii pneumonia have been described in Europe and Iran (1), these cases occurred primarily in premature and debilitated infants. In the United States, most cases of P. carinii in-fection have been sporadic and have occurred in immuno-logically deficient hosts. However, there have been reports of familial cases and multiple cases in hospitals treating patients with neoplastic disease (2-4). We describe a cluster of 11 cases of P. carinii pneumonia occurring over a 3-month period in a hospital treating patients with neo-plastic diseases