Epidemiological and phylogenic study of human metapneumovirus infections during three consecutive outbreaks in Normandy, France.

International audienceHuman metapneumovirus (hMPV) is responsible for respiratory tract disease, particularly in the young and elderly population. An epidemiological and phylogenic study was performed on children admitted to hospital with an acute lower respiratory tract infection. Data was obtained and analyzed over three consecutive winters, from 2002-03 to 2004-05. Each year during the winter period, from November to March, 2,415 nasal swabs were tested by a direct immunofluorescence assay (DFA) for influenza virus A and B, respiratory syncytial virus, parainfluenza viruses and adenoviruses. Rhinoviruses, enteroviruses and coronaviruses OC43 and 229E were detected by RT-PCR. A RT-PCR designed for the M gene was performed on negative samples for hMPV detection and phylogenic analyses. For the three consecutive winters, hMPV represented 10%, 22.6% and 8.8% of virus-negative samples, respectively. In most cases, clinical symptoms indicated a lower respiratory tract infection (LRI) with a final diagnosis of bronchiolitis. During the winter of 2003-04, all viral clusters (A1, A2, B1 and B2) that circulated in France shifted progressively from the A group to the B group. This study determined the prevalence of hMPV in Normandy, its clinical impact and permitted the analysis of the molecular evolution during the successive outbreaks