Epidemiological characteristics and trend analysis of influenza-like cases in Xuhui District of Shanghai from 2010 to 2019 / 上海预防医学

ABSTRACT

ObjectiveTo analyze the epidemiological characteristics and incidence trend of influenza-like illness in Xuhui District from 2010 to 2019， in order to understand the patterns of influenza epidemic of Xuhui District，and to provide evidence for the prevention and control of influenza in the future. MethodsSurveillance data of influenza-like illness （ILI） in Xuhui District from 2010 to 2019 were collected from the National Influenza Surveillance System for statistical description and trend analysis. ResultsFrom 2010 to 2019， the overall proportion of influenza-like illness was 0.54%. The annual proportions of ILI were between 0.35%~1.14%．The majority of cases were reported in age group of 25~59， accounted for 54.50% of the total ILI. A total of 9 053 throat swab specimens from ILI patients were collected and tested， from which 2 137 specimens were positive， with a positive rate of 23.61%. The most frequent subtype of influenza virus detected was influenza A virus （accounting for 67.62%）. The proportion of ILI and the positive rate of influenza virus nucleic acid detection reached the peak in summer and winter over time. There was a positive correlation between the proportion of ILI and the positive rate of influenza （r=0.666， P<0.01）. From 2010 to 2019， both ILI% and nucleic acid positive rate of influenza virus showed a downward trend. ConclusionThe incidence of influenza shows a downward trend in Xuhui District， with two peaks in summer and winter. The most susceptible individuals are in 25~59 age group. The dominant strains of influenza virus alternate regularly， influenza A（H3N2） dominate the summer epidemic peak while the epidemic peak in winter is dominated by influenza A（H1N1） and influenza B.