Analysis of influenza surveillance in Xi’an city, 2007-2008

Objective　The study was conducted to identify the epidemic trend of influenza, provide the evidence for the control of influenza. Methods　Descriptive epidemiological analysis was performed on the data of annual influenza-like cases surveillance, virus isolation/identification and the information of influenza outbreak in Xian from 2007 to 2008. Results　A total of 17 071 cases of influenza-like cases were reported from three sentinel hospitals in Xian from October 2007 to the end of March 2008, and 559 samples were collected from influenza-like cases, 50 strains of influenza virus were isolated with the isolation rate of 8.94%. Six strains of H3N2 and 44 strains of B influenza virus were detected, the predominant strain was B influenza virus. Conclusion　The epidemic situation of influenza was relatively stable in Xian from 2007 to 2008. The predominant strain was B influenza virus. Two outbreaks were caused by H3N2 influenza virus which indicated active variation of the virus. Therefore, it is vital to perform influenza surveillance for the better understanding of influenza epidemic and effective prevention and control the epidemic in Xian.