Human metapneumovirus in children tested at a tertiary-care hospital

Background. Respiratory infections are the leading cause of outpatient visits in the United States, but the etiology of many of these infections is unknown. Human metapneumovirus (hMPV) is a recently discovered virus that causes respiratory infections. Methods. Respiratory specimens obtained from patients less than or equal to18 years old, between 1 October 2000 and 31 August 2002, were tested for hMPV. The results of testing for other viruses and epidemiological information were obtained from the hospital databases. A logistic regression model, including sex and age of the patient and year and season in which the specimen was obtained, was used to determine the factors associated with hMPV infection. Results. hMPV was detected in 6.2% of patients tested and was significantly more common among children 3-24 months old than in older or younger children. The seasonal occurrence of hMPV was similar to that of respiratory syncytial virus and influenza virus, with most cases occurring in the winter and spring. In this tertiary care-center population, patients with hMPV infection often had underlying chronic conditions. Conclusions. hMPV is common among young children with apparent respiratory infections, suggesting that it is a significant cause of symptomatic respiratory infections.