北京市某区两起小学乙型流感暴发疫情调查

目的分析北京市某区两起小学乙型流感暴发疫情的流行病学特征,为流感暴发疫情的防控提供参考。方法对2010年1月北京市某区两起小学乙型流感暴发疫情进行临床诊断、流行病学分析及实验室病毒分离检测。并将分离结果与同期监测来源毒株、疫苗株序列进行比对分析。结果这两起乙型流感疫情暴发分别在一个班级范围内。罹患率分别为42.2%(19/45)和42.9%(18/42)。采集18件病人咽拭子样本,其中A校8件,B校10件。病毒分离得到5株乙型流感Victoria系毒株,其中A校2株,B校3株。与同期监测分离的4株乙型流感病毒以及乙型流感疫苗株进行序列比对,疫情与监测来源的毒株样本高度同源,与监测优势株型别一致,并与WHO推荐的2009~2010年乙型流感疫苗株同源性高达98.9%以上。结论流感流行优势型别更替时间段内容易暴发流感疫情,两起疫情均由乙型Victoria系引起。北京市流感样病例病原学监测为预测流感流行趋势提供依据,同时可对疫情的发生提供预警。

Retrospective analysis of two outbreaks of flu B infection in primary schools of one district in Beijing

Objective To analyze the epidemiological characteristics of two outbreaks of flu B infection in primary schools of one district in Beijing, so as to provide reference for the prevention and control of influenza outbreaks. Methods To make clinical diagnosis, epidemiological analysis and virus isolation in laboratory of two outbreaks of flu B infection in primary schools of one district in Beijing in January 2010 and make sequence alignment of the isolated virus with monitoring source strains and the vaccine strain. Results Both flu outbreaks were within a class. Attack rates were 42.2% （ 19/45）, 42.9% （18/42） respectively. Eighteen throat swab samples were collected, including 8 samples from School A and 10 from school B. Five Influenza B Victoria strains were isolated, two from school A, three from school B. Sequence alignment was made between these 5 strains and the 4 strains isolated from the monitoring of the same time and the vaccine strain. There was highly homologous between viruses isolated from the outbreaks and the monitoring source, and the type was consistent with the dominant strains from the monitoring. The homology was over 98.9% with the WHO recommended 2009 - 2010 influenza vaccine strain. Conclusion Flu is easy to break out when the dominant strains are replaced. The two outbreaks were caused by B Victoria influenza. Pathogens monitoring of influenza-like illnesses in Beijing provides a basis for predicting influenza epidemic trend, and also can provide early warning of the flu outbreaks.