上海市宝山区某小学一起呕吐疫情感染来源与环境污染情况调查

Investigation on the Source of Infection and Environmental Pollution in a Vomiting Outbreak in a Primary School in Baoshan District

目的:探讨上海市宝山区某小学一起诺如病毒引起暴发性呕吐事件的流行病学特征,为学校聚集性呕吐事件规范处置提供科学依据。方法:运用现场流行病学方法,收集2020年12月21—31日病例的基本信息,运用描述性流行病学方法对暴发疫情流行特征和危险因素进行分析,采集病例、密接和环境相关标本,进行肠道病毒核酸检测。结果:宝山区某小学该起暴发疫情共报告病例74例,罹患率为9.25%,主要临床表现为呕吐、发热。病例发病的高峰集中在12月25—27日。患者分布在14个班级内,首发病例所在的南楼学生发病率高于北楼学生(χ^(2)=20.532,P<0.01),2年级学生的发病率高于1年级学生(χ^(2)=30.897,P<0.01),4楼学生的发病率高于其他楼层学生(χ^(2)=96.388,P<0.01)。共采集31份肛拭子及环境标本,其中8份病例诺如病毒GⅡ核酸阳性,2份环境涂抹样本诺如病毒GⅡ核酸阳性,其余标本均为阴性。结论:该起事件为一起GⅡ型诺如病毒暴发疫情,首发病例呕吐物处置不规范及发病后未采取相关隔离措施,是造成该起疫情在人际间传播的主要原因。

OBJECTIVE To explore the epidemiological characteristics of a fulminant vomiting incident caused by norovirus in a primary school in Baoshan district,Shanghai,so as to provide a scientific basis for the standardized handling of clustered vomiting incidents on campus.METHODS On-site epidemiological method was used to formulate case definitions and collect cases’basic information from December 21 to December 31.Descriptive epidemiological methods were applied to analyze the epidemiological characteristics and risk factors of the outbreak,cases and close contacts and environmental-related specimens for enterovirus nucleic acid detection.RESULTS 74 cases of the outbreak were reported in a primary school in Baoshan district,with prevalence of 9.25%.The cases were focused on December 25-27.The patients were distributed in 14 classes.The incidence rate in the south building where the first case was located was higher than that in the north building(χ^(2)=20.532,P<0.01),and the incidence in the second grade was higher than that in the first grade(χ^(2)=30.897,P<0.01).The incidence rate of the building was higher than that of other floors(χ^(2)=96.388,P<0.01).31 anal swabs and environmental specimens were collected,of which 8 cases were positive for Norovirus GⅡnucleic acid,2 cases of environmental smear were positive for Norovirus GⅡnucleic acid,and the rest were negative.CONCLUSION The incident was a clustered vomiting epidemic caused by norovirus.The first case was vomiting in a school public place,and the vomit was not handled in a standardized manner,which was spread in homes and schools through human-to-human or human-to-human transmission.