Abstract: Abstract Objective: To understand the epidemiologic feature of virus infection in the children with acute respiratory tract infections in Tianjin area. Methods: From January 2010 to June 2011, 5954 hospitalized children with acute respiratory tract infection were studied. Nasopharyngeal aspirates were detected for seven kinds of the respiratory tract virus by direct immunofluorescent assay. Results: Viruses were identified in 626 patients, the positive ratio was 10.51 %, the majorty of them were under 2 years old. The most prevalent virus was respiratory syncytial viruses (RSV) (376, 60.06 %)，followed by parainfluenza 3 (211, 33.71 %), adenovirus (20, 3.19 %), influenza A (6, 0.96 %)，parainfluenza 1 (5, 0.80 %), influenza B (3, 0.48 %), parainfluenza 2 (2, 0.32 %) and coinfection (3, 0.48 %). RSV was maximum for the children between 0 to 12 years old. The seasonal change of RSV and PIV 3 was obvious. RSV was most detected in spring and winter, and the peak of PIV 3 appeared in summer. Conclusion: RSV and PIV 3 was the most common viruses in children with acute respiratory tract infections in Tianjin area, especially in children under 2 years old. Both RSV and PIV 3 had their own epidemiologic feature in different seasons.

Key words: Acute respiratory tract infection, Virus, Children, Epidemiological research