Human Metapneumovirus Infection in the United States: Clinical Manifestations Associated With a Newly Emerging Respiratory Infection in Children

OBJECTIVE: Respiratory tract infections are a leading cause of morbidity and mortality worldwide. Recently, a newly identified human respiratory virus, human metapneumovirus (hMPV), was reported by investigators in the Netherlands. We sought to determine whether hMPV was circulating in our community and to determine the clinical features associated with hMPV infection. METHODS: Respiratory specimens from children who were younger than 5 years and had a negative result for respiratory syncytial virus, influenza A and B, parainfluenza viruses 1 to 3, and adenovirus by direct fluorescent antibody test were screened for hMPV by reverse transcriptase-polymerase chain reaction. Samples were collected from October 30, 2001, to February 28, 2002. RESULTS: Of the 296 patients screened, 19 (6.4%) had evidence of hMPV infection. hMPV was identified in patients with either upper or lower respiratory tract infection or both. Clinical manifestations included wheezing, hypoxia, and abnormal findings on chest radiographs (eg, focal infiltrates, peribronchial cuffing). Nosocomial infection occurred in at least 1 patient. CONCLUSIONS: hMPV is circulating in the United States and is associated with respiratory tract disease in patients with respiratory illnesses not caused by respiratory syncytial virus, influenza, parainfluenza viruses, and adenovirus. Additional studies are required to define the epidemiology and the extent of disease in the general population caused by hMPV.