Acute lower respiratory tract infections by human metapneumovirus in children in Southwest China: a 2-year study.

Human metapneumovirus (hMPV) has been reported to cause both upper and lower respiratory tract diseases in susceptible populations, particularly in children and the elderly. In this study, we describe a hospital-based epidemiological study of hMPV in patients presenting to a children's hospital and show the demographic and clinical characteristics associated with hMPV infection in China, retrospectively. Specimens were collected over a 2-year period from children hospitalized with acute lower respiratory tract infections (ALRTI) and analyzed for the presence of hMPV using real-time RT-PCR assays. The presence of hMPV was detected in 227 (25.9%) of the 878 children studied and may circulate year-round in the area, peaking during the winter-spring season. Younger children (aged less than 6 months) had the highest positive rate. Infections by hMPV showed similar epidemiology and clinical manifestations as for respiratory syncytial virus (RSV) and were found in high co-infections with RSV. Subgroup A2 hMPV was the most predominant genotype identified during the study period. This study indicates that hMPV is one of the major respiratory pathogens found in children in southwest China and vaccine development should be under consideration.