[Respiratory infections due to metapneumovirus in hospitalized infants].

Human metapneumovirus (hPMV) is a recently identified virus that is recognized as a cause of respiratory tract illness in the pediatric population. To determine the incidence of respiratory tract infections caused by hPMV in hospitalized infants and to describe the clinical characteristics and possible presence of coinfection with other viral agents. We performed a prospective study from September to June 2003 in all children aged less than 24 months who were admitted to the Severo Ochoa Hospital (Leganés, Madrid) with a respiratory tract infection. Virological diagnosis was made with a direct immunofluorescent assay and/or reverse transcriptase-polymerase chain reaction on specimens obtained from nasopharyngeal washing. Demographic and clinical data from patients with an hPMV respiratory tract infection were analyzed. During the study period, 200 infants were admitted with a respiratory tract infection, of which 18 (9 %) had an hPMV infection. HPMV was the viral agent isolated in 13.8 % of positive nasopharyngeal washings. All patients were admitted between March and April. The mean age was 6.7 +/- 6.1 months. The most common diagnoses were recurrent wheezing (55.5 %) and bronchiolitis (38.8 %). Oxygen therapy was required by 55.5 % of infants during hospitalization. Coinfection with other respiratory viruses was confirmed in 33.3 % of the patients. Human metapneumovirus is a major cause of respiratory tract illness in hospitalized infants. This virus causes mainly bronchiolitis and recurrent wheezing and is more frequent in spring. Coinfection with other respiratory viruses is frequent.