Surveillance of influenza in Guangxi, 2007 - 2009

Objective To monitor the influenza epidemic and the predominant strains of influenza viruses in Guangxi and provide scientific evidence for the prevention and control of influenza. Methods The influenza-like illness cases were recorded daily in 4 sentinel hospitals, and samples were taken from eligible cases to isolate influenza viruses by cell culture. Results The obvious incidence peaks of influenza like illness were found in Spring and Summer from 2007 to 2009, and the influenza-like illness cases accounted for 11.34%, 12.45% and 7.10% of the total outpatients in the sentinel hospitals respectively. A total of 134 strains of influenza viruses were isolated in 2007, of which 58 were identified as influenza B virus, 69 strains as influenza A (H3N2) virus and 7 as influenza A (H1N1); A total of 82 strains of influenza viruses were isolated in 2008, 33 were identified as influenza B virus, 30 as influenza (H3N2) virus and 19 as influenza A (H1N1) virus, A total of 1737 strains of influenza viruses were isolated in 2009, 192 were identified as influenza B virus, 176 as influenza A (H3N2) virus, 74 strains as influenza A(H1N1) virus and 1295 strains as pandemic influenza A(H1N1) virus. Conclusion Influenza-like illness cases were detected in sentinel hospitals all the year round with the incidence peak during Spring-Summer from 2007 to 2009. Influenza A (H3N2) virus and influenza B virus were predominant in 2007 and 2008, and pandemic influenza A (H1N1) virus was predominant in 2009.