2011—2015年北京市海淀区流感监测结果分析

Analysis of influenza surveillance in Haidian District of Beijing, 2011 -2015

目的分析2011—2015年北京市海淀区流感病例的流行病学特征，为海淀区流感防控措施调整提供科学依据。方法对2011—2015年北京市海淀区63家哨点医院流感样病例（Influenza—like illness，ILl）报告数据和2011年9月-2015年8月一家国家级流感监测医院病原学监测标本检测结果进行分析。结果2011—2015年海淀区63家哨点医院共监测门急诊就诊病例49228815例，其中ILI362410例（占0．74％）。5年的流感样病例占门急诊就诊总数的比例（ILI％）不同（X^2=1103。798，P〈0．05）。2011-2015年各年龄组中的ILI构成情况每年与其他年份比较均不相同（P〈0．005）。2011年9月-2015年8月四个流感病原学监测季，共采集ILI咽拭子样本4183件，检出阳性标本766件，总阳性率为18．31％。2013—2014年监测季与2014—2015年监测季流感病毒核酸检测阳性率不同（X^2=6．955，P=0．008），2011—2015年各个监测季中流感病毒型别的构成情况均不相同（P〈0．05），周流感病毒核酸检测阳性率与周ILI数和周ILI％均呈正相关（r=0．579，P〈0．05；r=0．602，P〈0．05）。结论海淀区流感流行特征有一定规律，每年第50周（12月）至第二年第16周（4月）为季节性流感的发病高峰。2014—2015年流感流行较往年相比更为活跃，优势毒株为甲型H3N2型流感病毒。各年度流感优势毒株型别均不相同，具有当年度中此消彼长的流行特点。

Objective To analyze epidemic characteristics of influenza virus in Haidian District of Beijing from 2011 to 2015 and to provide scientific basis for influenza prevention and control. Methods The numbers of influenza-like illness（ILI） cases reported by 63 sentinel hospitals of Haidian district from 2011 to 2015 and the detection results of etiological surveillance samples collected from one national influenza surveillance hospital from Sep 2011 to Aug 2015 were used to analyze. Results Among 49 228 815 cases in outpatient and emergency in 63 sentinel hospitals from 2011 to 2015, the ILI count and rate were 362 410 and 0. 74%, respectively. Proportions of ILI（ ILI% ） in all surveillance cases were different in 5 years（x2 = 1 103. 798, P 〈0. 05）. Age group compositions of ILI varied from 2011 to 2015（P 〈0. 05）. From Sep 2011 to Aug 2015, 4 183 throat swab specimens were collected from ILI cases during 4 influenza etiological surveillance seasons and 766 specimens were tested positive for influenza. The total positive rate was 18.31%. Positive rates of influenza virus nucleic acid detection in the season during 2013- 2014 were different during 2014-2015（X2 = 6. 955, P = 0. 008）. And subtype compositions of influenza virus varied in different surveillance seasons from 2011 to 2015 （P 〈 0. 05）. Weekly positive rates were positively related to weekly numbers of ILI cases and weekly ILI% （ r = 0. 579, P 〈 0. 05; r = 0. 602, P 〈 0. 05, respectively）. Conclusions There were certain rules of influenza epidemic characteristics in Haidian District that the peak onset of seasonal flu was from the 50th week （December） to 16th week （April） in the next year. Influenza epidemic was more active in the season from 2014 to 2015 than in previous years, and the subtypes of dominate strain was A （H3N2）. The dominate influenza virus subtypes varied in different years with the feature that decline of one dominate subtype accompanied with growth of another one in one year.