一起学校食源性诺如病毒感染性腹泻暴发疫情调查

Investigation of a food- brone outbreak of an infectious diarrhea caused by Norovirus in students of a school

目的对江门市某学校发生的一起聚集性腹泻暴发疫情进行调查和分析。方法采用描述性流行病学和回顾性队列研究的方法,分析发病原因、感染途径及其危险因素;对学校食堂开展现场卫生学调查,采用RT-PCR方法检测诺如病毒核酸。结果疫情从2014年11月20日0时持续至21日16时,共报告87例病例,罹患率0.67%。临床表现较轻,以恶心、呕吐和腹痛为主。病例全部为学生,女生罹患率高于男生。疫情持续40h,发病曲线呈单峰,病例在宿舍、班级空间分布上无集聚性。11份病人肛拭子标本有5份诺如病毒GⅡ型阳性。18、19日在A公司大众早餐部刷卡吃早餐是发病的危险因素。结论本次事件为一起发生在学校的由诺如病毒GⅡ型引起的集聚性感染性腹泻暴发疫情,18、19日在A公司大众早餐部刷卡吃早餐是发病的危险因素,感染途径为食源性。

Objective To investigate a clustering outbreak of an infectious diarrhea caused by Norovirus in studens of wschool in Jiangmen city. Methods The Cause, transmission mode and risk fsctors of an infectious diarrhea in a school weresurveyed using descriptive epidemiology methods. RT- PCR was used to determine the pathogens in the samples. Aretrospective cohort study was used to analyze the risk factors of this outbreak. Results From November 20 to November 21,2014, a total of 87 cases were found in the school, with an attack rate of 0.67%（87/12 956）. The main clinical symptoms werenausea, vomit and abdominal pain. All of the cases were students, and the attack rate of female（1.0%）was higher than that ofmale（0.32%）. The distribution of cases in classes and dormitories did not appear any distinct spatial aggregation. Theincidence curve of the cases number against the onset-time showed one single peak. Retrospective cohort study showed that thestudents having breakfast served by the Dazong Breakfast Company in the school canteen on November 18 and 19 appearedhigher attack rate（P〈0.05）. And 5 out of 11 fecal samples were positive for norovirus nucleic acid in PC- PCR tests.Conclusion The infectious dirrhea outbreak in a school of Jiangmen was caused by Norovirus G Ⅱ infection. The maintransmission mode was via the intake of Norovirus contaminated food.