Analysis on Surveillance of Influenza in Guangzhou City in 2003

Objective To analysis and summarize the influenza epidemic tendency and the etiological characteristics on the basis of results made by the influenza-monitoring network in Guangzhou city in 2003. Methods Epidemiological surveillance, forms of influenza-like cases should be filled and filed weekly in monitoring point hospitals; individual cases of influenza-like disease should be surveyed and reported by CDC doctors at district and county level. Etiological surveillance, 5-10 portions of mouth rinsing liquid should be col-lected weekly from patients with influenza-like disease in monitoring point hospitals to do influenza virus sepa-ration. Serological monitoring,to monitor the antibody level of sera of common peoplie in March and Septem-ber;and to monitor the influenza sera of people vocationally exposed in poultry.Results 91 outbreak of in-fluenza epidemic were reported all the year,and the morbility rate was from 0.35% to 40%. For etiological monitoring,influenza A (H3N2)was found to be the predominant strain throughout year,and the influenza B only caused sporadic cases or small-scale outbreak.For serological surveillance,two results in March and September showed that,bef\ore and after the peak of influenza,positive rates of H1N1、H3N2、B (Victorian se-ries) sub types were identical (X2=0.82,2.01,1.34,P>0.05),but B (Panama series) antibody in Septent-ber was higher than that in March (X2=0.022,P1N1、H3N2、B were 42.97%、 88.21%、59.09%，respectively. The H5N1 test results of poultry were all negative. There were 5 positive H3N2 cases,and the positive rate was 1.89%.Conclusion High incidence of influenza occurred between spring and summer in 2003,and the H3N2 was the predominant epidemic strains in the whole year.