上海市某幼儿园一起札如病毒引发的胃肠炎疫情流行分析

Epidemiological characterization of sapovirus gastroenteritis aggregation in a kindergarten in Jinshan District,Shanghai

[目的]分析一起札如病毒性胃肠炎疫情的流行病学特征及其感染病毒基因型别,为制订有效控制策略提供科学依据。[方法]制定统一病例定义,开展主动病例搜索,采用描述性流行病学对该起疫情进行分析。采集未经治疗发病幼儿粪便或肛拭子、带班老师、食堂员工及食堂环境样本、发病班级环境样本,运用实时荧光聚合酶链反应(RT-PCR)检测诺如病毒及札如病毒核酸。采用常规逆转录RT-PCR扩增部分札如病毒衣壳蛋白基因区,应用MEGA7.0等软件分析基因序列,构建系统进化树。[结果]本次疫情共报告12例病例,报告于同一个班级,病例均有呕吐症状,全班级罹患率为44.44%。疫情呈现点源性暴发,首发病例带病上课为传染源,疫情持续8 d。实时荧光RT-PCR检测证实5份患儿粪便札如病毒核酸阳性,首发患儿粪便札如病毒及GⅡ型诺如病毒核酸阳性。序列比对结果显示,扎如病毒基因序列均属于GI.1型,基因同源。[结论]根据病例临床表现、现场流行病学调查及实验室检测结果,确认本起疫情因首发病例带病上课,由GI.1型札如病毒感染导致聚集性疫情,通过病例隔离及消毒等综合性措施可有效控制疫情。

[Objective]To analyze the epidemiological characteristics of an aggregational gastroenteritis and determine the genotypes of sapovirus,and to provide scientific basis for formulating effective control strategies.[Methods]Unified case definition,active case search and descriptive epidemiology were used to analyze the epidemic.Feces or anal swabs of untreated students,teachers,canteen staff as well as canteen environment samples were collected.Norovirus and sapovirus nucleic acid tests were conducted by real-time fluorescent RTPCR,and sapovirus nucleic acid was amplified by conventional RT-PCR.The gene region of capsid protein was analyzed by MEGA7.0 software and phylogenetic tree was constructed.[Results]A total of 12 cases were reported in the epidemic,and the incidence rate was 44.44%.All reported cases,with vomiting symptoms,were found in the same class.The epidemic showed a point-based outbreak.The first case became the source of infection in class,and the epidemic lasted for 8 days.Real-time fluorescent RT-PCR assay confirmed that five children's feces were positive for sapovirus nucleic acid,and the first-episode children's feces were positive for sapovirus and GII norovirus nucleic acid.Sequence alignment result showed that the sapovirus strains belonged to GI.1 type with homologous genes.[Conclusion]Based on the clinical manifestations,field epidemiological investigation and laboratory test results,we confirm that the first case of the epidemic in class is caused by GI.1 sapovirus infection.The epidemic is effectively controlled by comprehensive measures such as case isolation and disinfection.