Analysis on epidemiological characteristics of influenza in Daxing district of Beijing, 2014-2017

Abstract

Objective To analyze the epidemiological characteristics of influenza in Daxing district from 2014 to 2017. Methods Data of influenza-like illness cases in Daxing district each week from 2014 to 2017 were collected from Beijing Surveillance and Early Warning System for Infectious Disease. Positive results of influenza virus surveillance within the district were collected weekly. The time distribution curve was plotted for the analysis of the characteristics of surveillance data. Results During the period of 2014-2015, 2015-2016 and 2016-2017, the percentages of influenza-like illness cases in Daxing district were 0.62%, 0.54% and 0.58%, respectively. A total of 3 125 samples from influenza-like illness cases were tested. Two hundred and sixty-four samples were positive for influenza virus, including 149 influenza A(H3N2), 50 influenza A(H1N1), 48 influenza B/Victoria and 17 influenza B/Yamagata. The positive rates of influenza virus in the three seasons were 5.38%, 5.48% and 14.45%, respectively. Correlation analyses were applied to the number of or the percentage of influenza-like illness case with the positive rate of influenza virus. The Pearson correlation ratios were 0.56 (P<0.01) and 0.57 (P<0.01), respectively. Conclusions The dominant influenza viruse strains in Daxing district from 2014 to 2017 were all seasonal influenza viruses. Surveillance data of influenza-like illness cases had basically the same trend as that of etiological results. Both data could reflect the prevalence of influenza in Daxing district. Key words: Influenza; Epidemics; Epidemiology; Influenza-like illness case; Surveillance