[Human metapneumovirus--occurrence and clinical significance].

BACKGROUND: Human metapneumovirus (hMPV) was isolated for the first time in 2001 from young children with acute respiratory tract infection.

MATERIALS AND METHODS: Review of published data on the clinical impact of hMPV and our own experience with hMPV during three winter seasons. We present four cases of severe hMPV childhood infections.

RESULTS: Human metapneumovirus accounts for approximately 10% of respiratory tract infections that are not related to previously known etiologic agents. The virus seems to be distributed worldwide and to have a seasonal distribution. During a short epidemic, 60% of our isolates from children with respiratory infection tested positive for hMPV. Serologic studies have shown that by the age of five, virtually all children have been exposed to the virus and reinfections appear to be common. Human metapneumovirus may cause mild respiratory tract infection. Small children, elderly and immunocompromised individuals are, however, at risk of severe disease and hospitalization. Although the clinical manifestations of hMPV resemble those of respiratory syncytial virus, we have observed that hMPV more often causes severe pneumonia in hospitalized children.

INTERPRETATION: Human metapneumovirus is an important cause of acute respiratory tract infection in children. The virus may cause severe disease in patients at risk. We recommend identification and isolation of hospitalized hMPV-infected patients.