Detection and strain typing of influenza viruses in Nanping,Fujian,2009

Objective To investigate 2009 epidemic strains of influenza viruses in Nanping,Fujian province.Methods The respiratory tract swabs of influenza-like patients were collected from 2 hospitals for influenza sentinel surveillance.Influenza viruses were isolated with MDCK cells and subtype identification was confirmed with hemagglutination inhibition(HI) test.Results 1 848 swab specimens were tested and 240(13.0%) were influenza virus positive.85 isolated influenza viruses were H1N1 strain,42 were H3N2,56 were influenza B and 57 were the 2009 new strain of H1N1 influenza A virus.The high activity of influenza viruses was observed in summer(May-September) and early winter(November-December).The epidemic strains of viruses were H3N2,H1N1 and influenza type B(B-yamagata,B-victoria) in summer.The predominant strains isolated in the early winter of 2009 were the new influenza A H1N1 and influenza B.Conclusion The new strain of H1N1 influenza virus caused influenza outbreak in the winter of 2009 and additional monitoring efforts are required for the disease surveillance in future.