2015-2016年北京市朝阳区流感流行特征及病原学分析

Epidemiological analysis of surveillance for influenzain Chaoyang District,Beijing,2015-2016

目的分析北京市朝阳区2015-2016年度流行性感冒(流感)流行特征,为今后流感防控工作提供科学依据。方法对北京市朝阳区2015-2016年度的流感样病例(influenza-like illness,ILI)报告数据、流感病原学监测数据以及流感聚集性疫情情况进行流行病学分析。结果 2015-2016年度北京市朝阳区共报告ILI病例187 072例,平均流感样病例的百分比(%)为2.42%。ILI病例数和ILI%均呈明显的季节性特征,在冬季出现一个高峰,峰值分别出现在2016年的第6周和第7周。报告的ILI病例以0~4岁组为主,占总数的44.78%。本年度共采集流感样病例咽拭子标本2 082件,检测流感病毒核酸阳性397件,检出率为19.07%。检出率出现第31~40周和第51周至次年第13周两个明显的高峰,以冬季高峰为主。本年度4种型别的流感病毒均有检出,B(Yamagata)系、A(H3N2)和B(Victoria)系交替成为主要的流行株。2015-2016年度,北京市朝阳区报告流感聚集性疫情43起,发生在托幼机构和小学的疫情最多,为42起(97.67%)。ILI%、ILI病例数均与流感病毒检出率呈正相关(rs=0.644,P<0.001;rs=0.600,P<0.001)。结论 2015-2016年度北京市朝阳区不同亚型流感病毒交替流行,ILI监测、病原学监测和聚集性疫情的特征基本一致。加强监测对于辖区内流感防控具有重要意义。

Objective To analyze the epidemiological characteristics of influenza in Chaoyang District in Beijing from 2015 to 2016,so as to provide specific evidence for making preventive and control strategies of influenza. Methods Weekly data were collected from influenza-like illness（ ILI） report,pathogen surveillance and influenza outbreak report in Chaoyang District in Beijing. Results From 2015 to 2016,a total of 187 072 ILI were reported from the sentinel hospitals in Chaoyang District,with the average of ILI% was 2. 42%. The majority of cases were reported fromage group of 0-4,accounted for 44. 78% of the total ILI. There was one peak in winter,and the peak of ILI and ILI% emerged in the 6th week and the 7th week in 2016 respectively. A total of 2 082 swab samples from ILI patients were collected and tested,from which 397 specimens were RNA positive,with a positive rate of 19. 07%. Two marked epidemic peaks appeared from the31 st week to the 40 th week and from the 51 st week to the next 13 th week,and the second one was more distinct. During this year,four subtypes of influenza virus were observed,and B Yamagata lineage virus,A（ H3N2） and B Victoria lineage virus appeared as the dominating strains alternately. From 2015 to 2016,43 cluster events of influenza were reported totally,and 42（ 97. 67%） of them occurred in childcare facilities and primary school. There were positive correlations both between ILI%,ILI counts and the positive rate of influenza（ rs= 0. 644,P 〈0. 001; rs= 0. 600,P 〈0. 001）. Conclusions Different virus sub-types prevailed alternatively from 2015 to 2016. There were similar characteristics among ILI,pathogen surveillance and cluster events of influenza. Enhanced and continuous surveillance is important for the prevention and control of influenza.