Serious outbreak of human metapneumovirus in patients with hematologic malignancies.

Human metapneumovirus (hMPV) is an important cause of lower respiratory tract infection. In healthy subjects infections are usually mild and rarely necessitate hospitalization. However, more serious outcomes have been described for allogeneic stem cell transplant recipients. This study reports an outbreak of hMPV A2 infection in severely immunocompromised adult hematologic cancer patients in a tertiary care unit. HMPV RNA was detected in bronchoalveolar lavage or produced sputum from patients presenting with typical clinical features. A total of 15 patients were diagnosed in a period of 7 weeks. Molecular subtyping revealed infection with genotype A2a virus, implicating nosocomial transmission. Eleven patients (73%) were treated with intravenous immunoglobulins and ribavirin. Ten patients (65%) presented with severe dyspnea, five (33%) required mechanical ventilation. Four patients (26.6%) died from hMPV-associated pneumonia and consequent multi-organ failure. Thus, hMPV is a critical pathogen for patients with hematologic cancers warranting early detection.