Human Metapneumovirus Infection in Hospitalised Children with Acute Lower Respiratory Tract Infection in Hangzhou, China

Objectives: To investigate human metapneumovirus (hMPV) pathogens in children with acute lower respiratory tract infection (ALRIs) in Hangzhou, China. Methods: A total of 2911 paediatric patients with ALRIs hospitalised in our unit from January 2011 to December 2011 were enrolled. Their clinical characteristics were recorded and hMPV was detected by direct immunofluorescence. Results: hMPV was found in 70 (2.40%) samples. The positive rate was highest in children aged >1 to 3 years (3.32%), and lowest in children over 3 years (0.63%) with a significant difference among 3 different age groups (χ 2 =11.795, P=0.003). The positive rate were higher in bronchiolitis and asthma with infection, and lower in pneumonia and bronchitis with a significant difference among 4 different groups (χ 2 =9.270, P=0.026). The positive rates of hMPV in children with bronchiolitis and asthma with infection were 2.706 (95%CI: 1.057-6.924) and 2.806 (95%CI: 1.095-7.187) folds of that in children with pneumonia. Moreover, the positive rate was highest in spring with a rate of 5.87%, followed by winter (3.30%), autumn (0.44%) and summer (0.36%). It dramatically increased in spring, and peaked on March with a rate of 7.47% while no hMPV positive sample was found from July to September. Conclusions: hMPV is an important cause of ALRIs. hMPV infection commonly occurs in young children, and spring is the peak infection season in Hangzhou, China