Surveillance of influenza-like illness in Xicheng district in Beijing,2010-2011

Objective To understand the incidence of influenza in Xicheng district in Beijing and provide evidence for influenza prevention and control. Methods The throat swabs were collected from the influenza like illness (ILI) patients in two sentinel hospitals in Xicheng district to conduct RT-PCR for influenza virus nucleic acid detection, and MDCK cell was used for the isolation of virus. Results A total of 17 549 ILI cases were reported from October 2010 to April 2011, accounting for 2.24% of all outpatients (17 549/784 625). Among 905 throat swabs collected, 297 were positive in influenza virus nucleic acid detection (32.82%). Seventy influenza virus strains were isolated (23.57%), including 35 strains of A (H1N1) pdm 09 virus, 25 strains of seasonal A (H3) virus, 7 strains of B virus/Victoria lineage and 3 strain of A virus unspecified. Conclusion The incidence of influenza peaked during December-January in Xicheng district during 2010-2011, A (H1N1) pdm 09 virus, seasonal A (H3) virus and B virus co-circulated.