洛阳市某小学诺如病毒感染引起聚集性疫情的调查分析

Investigation and analysis on clustering epidemic situation caused by norovirus infection in a primary school in Luoyang City

目的调查分析某小学诺如病毒聚集性疫情流行特征、传播途径和危险因素,为疫情防控提供参考。方法采用现场流行病学调查方法和PCR实验室检测方法查明原因,通过描述性流行病学方法和病例对照研究分析疫情危险因素。结果本次疫情出现病例12例,其中实验室诊断病例2例,班级罹患率25.00%(12/48)。2份肛试子诺如病毒GⅡ型核酸检测阳性。首发病例可能为食源性感染,续发病例呈点源暴发特征,发病曲线有一明显单峰。主要危险因素为近距离(1 m内)暴露呕吐物(OR=15.00,P<0.01))和参与呕吐物清理(OR=15.40,P<0.05)。结论该事件为一起诺如病毒GⅡ型感染引起的聚集性疫情,发生原因可能是首发病例发生食源性诺如病毒感染,其呕吐物污染教室环境,引起诺如病毒气溶胶或接触传播的点源暴发。

Objective To investigate and analyze the epidemiological characteristics,transmission routes and risk factors of a clustered epidemic of norovirus infection in a primary school,so as to provide the references for epidemic prevention and control.Methods Field epidemiological investigation and PCR laboratory test were used to identify the causes,and the descriptive epidemiological method and case-control study were used to analyze the risk factors of epidemic situation.Results There were 12 cases in this epidemic,including 2 laboratory-diagnosed cases,and the class attack rate was25.00%(12/48).Two anal tests were positive for norovirus G Ⅱ nucleic acid.The first case may be a food-borne infection,and the recurring cases were characterized by point-source outbreaks,and the incidence curve had an obvious single peak.The main risk factors were exposure to vomit at close range(within 1 meter)(OR=15.00,P <0.01) and participation in vomit cleaning(OR=15.40,P <0.05).Conclusion This incident is a clustered epidemic caused by norovirus type G Ⅱ infection.It may be caused by the first case of food-borne norovirus infection,and its vomit contaminates the classroom environment,causing norovirus aerosol or contact with the point of transmission source outbreak.