Evidence of human metapneumovirus in children in Argentina

Human metapneumovirus (hMPV) is a virus, which was first associated with acute lower respiratory infection in children but is detected currently in all age groups. Clinical symptoms are similar to those described for respiratory syncytial virus (RSV) infections, ranging from mild respiratory illness to severe bronchiolitis and pneumonia in children. To date, no cases of hMPV have been reported in Argentina. In this study, 440 respiratory samples obtained during the period 1998-2002 from children under 5 years old with acute respiratory infection were evaluated. Routine detection for RSV, adenovirus, influenza, and parainfluenza was undertaken by immunofluorescent assay. Of the samples negative for these viruses, only 100 were available. All these samples were tested for hMPV by RT-PCR using primers for the L gene. Eleven out of 100 (11%) respiratory samples were positive for hMPV by RT-PCR. A higher frequency of detection was observed in spring. hMPV was detected in all the years studied, except in 2001. Ten out of 11 children positive for hMPV were hospitalized. Median age was 5 months. Of seven patients, five (71%) required oxygen supplementation. The most frequent diagnosis was bronchiolitis (86%), sometimes accompanied by conjunctivitis and otitis media. The present study showed that hMPV was associated with acute lower respiratory infections in children in Buenos Aires, Argentina. This evidence strongly suggests that hMPV is a common pathogen with a wide geographical distribution, which should be included in the routine diagnosis of respiratory viruses in young children.