2017年沈阳市1起学校诺如病毒暴发疫情调查

Investigation on a school outbreak of Norovirus in Shenyang City in 2017

目的调查沈阳市某学校1起诺如病毒暴发疫情,为有效控制疫情提供科学依据,也为减少类似疫情发生提供控制经验。方法按照病例定义标准开展病例搜索,采用描述和队列分析进行流行病学分析;采集的样本开展荧光定量聚合酶链式反应(PCR)核酸检测和细菌培养。结果 3月中旬学校发生诺如病毒感染性腹泻78例,罹患率7.75%;流行曲线呈现2个高峰,初期有明显的班级和楼层聚集性,后期病例散在分布,存在多种暴露方式;队列研究显示与首发病例座位的距离(χ~2=8.13,P<0.05)和乘坐校车(χ~2=5.30,P<0.05)可能是危险因素;采集6名病例肛拭样本4人PCR核酸诺如病毒GⅡ阳性。结论这起由诺如病毒GⅡ引起的学校感染性腹泻暴发疫情,早期呕吐物不及时消毒,导致局部传播,然后通过校车和公共水房引起多途径感染引发爆发蔓延。

[Objective]To investigate and analyze a school outbreak of Norovirus in Shenyang City,provide a scientific basis for effective control of the epidemic and offer control experience to reduce the occurrence of similar outbreak.[Methods] The cases were searched according to the case definition standard,and epidemiologic analysis was performed by descriptive and cohort study.The collected samples were detected by fluorescence quantitative polymerase chain reaction（PCR） and bacterial culture.[Results] In the middle of March,there were 78 cases of infectious diarrhea caused by Norovirus in the school,with the attack rate of 7.75%.The prevalence curve showed two peaks.There were obvious class and floor aggregation in the early stage and scattered case distribution in the late stage,with many ways of exposure.The cohort study showed that seat distance to primary case（χ^2=8.13,P〈0.05） and the school bus（χ^2=5.30,P〈0.05） were the risk factors.Among 6 anal swab samples,PCR results of4 cases were positive for Norovirus GⅡ.[Conclusion] The outbreak of infectious diarrhea in the school is caused by Norovirus GⅡ.In the early stage the vomitus has not disinfected as soon as possible,which causes the local transmission,and then the multiroute infection through the school bus and the public water room leads to an outbreak.