Outbreak of human parainfluenza virus 3 infections in a hematopoietic stem cell transplant population

Clinical manifestations and epidemiological features are described for a cluster of 12 cases of human parainfluenza virus 3 (HPIV3) infection that occurred among 64 allogeneic hematopoietic stem cell transplant (SCT) recipients in an 11-week period during spring 2000. Upper respiratory symptoms predominated. Pneumonia occurred in 3 patients and was a contributing factor in the death of 1 patient. Exposure histories and molecular analysis of HPIV3 isolates suggested that both community acquired and nosocomially transmitted infections occurred during this outbreak. A chain of transmission within the outpatient clinic appeared to have occurred in 4 outpatients and to have extended to 2 hospitalized patients. Molecular epidemiology was useful in discerning routes of transmission in this outbreak.