一起学校诺如病毒胃肠炎聚集性疫情调查分析

Investigation on the epidemic situation of norovirus gastroenteritis in a middle school

目的调查一起学校胃肠炎聚集性疫情,探讨疫情暴发的原因、传播途径及危险因素,为有效控制同类胃肠道暴发疫情提供参考经验。方法拟定病例定义搜索病例,采用描述性流行病学方法分析疫情的特征,采集病例的肛拭子、呕吐物及环境涂抹标本做病原学检测,采用病例对照研究分析主要危险因素。结果共搜索到病例21例,多数有呕吐症状,部分伴有腹痛、腹泻和恶心等症状。教师1例,学生20例,学生中807班、808班和809班罹患率分别为29.17%(14/48)、10.00%(5/50)、2.17%(1/46),班级罹患率差异有统计学意义(χ^(2)=15.279,P<0.001);男学生罹患率高于女学生(χ^(2)=4.326,P=0.038)。发病初期采集12份病例、外环境3份,经PCR检测共7份标本诺如病毒Ⅰ型阳性,其中病例6份(肛拭子4份、呕吐物2份)、环境样本1份(卫生间水龙头);疫情结束1周后采集病例12份、外环境6份,均未检出诺如病毒。病例对照研究显示,清扫或直接接触到呕吐物和与病例日常接触是发病危险因素(P<0.05)。结论本次疫情为一起由诺如病毒引起的人传人胃肠炎聚集性疫情,排除食源性和水源性可能,清扫或直接接触呕吐物和与病例日常接触为主要危险因素。

Objective This paper aims to investigate the epidemic situation of gastroenteritis in a school and explore the causes,transmission routes and risk factors,so as to provide reference for the effective control of similar gastrointestinal outbreaks.Methods The characteristics of the epidemic situation were analyzed by descriptive study.Anal swabs,vomit and environmental samples were collected for etiological detection,and a case-control study was used to analyze the main risk factors.Results A total of 21 cases were found,most of which had vomiting symptoms,some with abdominal pain,diarrhea and nausea.There was 1 teacher and 20 students.The attack rates of classes 807,808 and 809 were 29.17%(14/48),10.00%(5/50)and 2.17%(1/46),respectively.The attack rates were different(χ^(2)=15.279,P<0.001).The attack rate of male students was higher than that of female students(χ^(2)=4.326,P=0.038).The 12 cases and 3 environmental sam⁃ples were collected during the onset period,and 7 samples were positive by quantitative real-time PCR analysis,including 6 cases(4 anal swabs,2 vomitus)and 1 environmental sample(toilet faucet).One week after the end of the epidemic,the noro⁃virus were not detected in 12 cases and 6 environment samples.A case-control study showed that cleaning or direct contact with vomit and daily contact with patients were risk factors(P<0.05).Conclusion This outbreak is a person-to-person agglutinative gastroenteritis epidemic caused by norovirus,excluding the possibility of foodborne and waterborne transmission.Cleaning or direct contact with vomit and daily contact with the case is main risk factor of epidemic situation.