Contribution of human metapneumovirus to influenza-like infections in North Greece, 2005-2008

Following its detection in 2001, human metapneumovirus (hMPV) has repeatedly been reported as a respiratory pathogen, especially in children. This study was aimed at determining the proportion of hMPV infections in patients with influenza-like illness (ILI) during the three influenza seasons 2005-6, 2006-7, 2007-8 in northern Greece. We collected 380 nasopharyngeal swabs or aspirates from ILI patients during the winter seasons 2005-2008 and examined them for influenza viruses and hMPV by one-step real time RT-PCR and nested RT-PCR. Influenza viruses were detected in 151 of the 380 specimens (39.7%) and hMPV in 23 of them (6.05%). Co-infections with hMPV and influenza viruses were observed in seven cases. The majority of the ILI patients (60.5%) were 0-18 years old. However, the incidence of influenza was slightly higher in the age group of 19-60-year-olds, while the incidence of hMPV infections was higher in the age group of 0-18-year-olds. We conclude that hMPV plays an important role as a contributor in influenza-like infections, especially in children. It circulates in the community during influenza seasons and its clinical appearance can be confused with influenza symptoms. However, further research is needed to elucidate the quantitative and qualitative importance of hMPV infections.