Epidemiological Characteristics Analysis Of Influenza In Anhui Province From 2017 To 2018

Objective To analyze the epidemiological and etiological characteristics of influenza in Anhui Province from 2017 to 2018,and understand the the seasonal characteristics,population and regional distribution of influenza in anhui province and the changes of dominant strains of influenza in Anhui Province,to provide theoretical guidance for the formulation of influenza prevention and control strategies.Materials and Methods The surveillance data in Anhui Province of influenza-like cases and influenza pathogens in anhui province from 2017 to 2018 were provided by Anhui Provincial Center for Disease Control and Prevention from 2017 to 2018 were downloaded from“China influenza surveillance information system”.Excel 2003 software was used to count data and SPSS 16.0 software was used for statistical analysis.Results1.283827 cases of influenza-like illness were reported by 24 influenza surveillance sentinel hospitals in Anhui Province from 2017 to 2018,while the total number of outpatient and emergency clinc is 6423543.The average of ILI% was 4.42%.2.The number of ILI cases and ILI % have seasonal characteristics,with a peak in winter and summer,and the peak of ILI and ILI% emerged in August to September in 2017 and January in 2018 respectively.3.The proportion of ILI cases was highest in group 0 ~ 4(59.74 %),whereas lowest in age group 60 and above(3.36 %).4.There were 2 epidemics of influenza were detected in Anhui Province with a total of 63 cases from 2017 to 2018,which caused by influenza A(H1N1)strains and influenza B strains respectively,and all occurred in primary and secondary schools.5.From 2017 to 2018,a total of 38,869 isolated ILI samples were tested in anhui province,from which 5,490 specimens were positive for viral RNA,with a positive rate of 14.12 %.6.The positive rate of viral RNA was different among months and age groups,and the difference was statistically significant(all P < 0.001).The difference between the positive rate of influenza virus and different gender cases was no statistically significant(P > 0.05).The positive rate was highest in December 2017(18.84 %), lowest in June 2017(4.33 %).The positive rate was highest in group 15 ~24(20.72 %),lowest in age group 60 and above(6.51 %).7.The percentages of virus subtypes were significantly different among people in different months and age groups(all P < 0.001).The difference between the percentages of virus subtypes and different gender cases was no statistically significant(P > 0.05).8.The ILI counts was positively correlated with the ILI % and the positive rate of influenza(r = 0.585,P < 0.05;r = 0.691,P < 0.05).Conclusions1.From 2017 to 2018,the influenza of Anhui province is epidemic in winter and summer.The percentage of ILI in children under the age of 5 was the highes,and the number of ILI cases in winter 2018 has surged compared to 2017.2.From 2017 to 2018,seasonal A(H3)and new A(H1N1)altered to become the dominant strain in Anhui province,with mixed epidemic of B(Yamagata)and B(Victoria).3.The dominant strains of influenza are different in different age groups and regions.