一起幼儿园诺如病毒GⅠ.3和GⅡ.2混合感染引起聚集性疫情的调查

An epidemiological investigation about an outbreak of gastroenteritis caused by norovirus GⅠ.3 and GⅡ.2 in a urban kindergarten

目的分析南昌市某幼儿园一起诺如病毒GⅠ.3和GⅡ.2混合感染引起的聚集性腹泻流行特征及传播因素,为感染性腹泻防控提供科学依据。方法制定病例定义并开展病例搜索,通过病例个案调查和现场流行病学调查,分析流行特征和危险因素,采集病例肛拭样本和呕吐物及相关人员肛拭样本,采用实时荧光定量PCR方法对标本进行诺如病毒检测,并对阳性标本进行测序及基因分析。结果疫情累计发生病例9例,集中在一个班级,班级罹患率为47.37%,男女性别比为2∶1,临床表现以呕吐为主。保育员未按规范流程消毒处理首批病例呕吐物,并在处置呕吐物时未转移班上儿童。采集6例现症病例肛拭和呕吐物样本,3例患儿肛拭样检测结果为诺如病毒GⅡ,1份呕吐物为诺如病毒GⅡ;1例患儿肛拭样为诺如病毒GⅠ,3例密接人员检测结果均为阴性。病毒序列分析结果显示本次疫情的病原体为诺如病毒GⅠ.3和GⅡ.2基因型。结论本次疫情为诺如病毒GⅠ.3和GⅡ.2同感染引起的急性胃肠炎聚集性疫情。幼儿园发生疫情后,应及时报告,并采取病例监测、消毒隔离、健康宣教等防控措施。

Objective To investigate and analyze the epidemiological characteristics of an outbreak of norovirus norovirus GⅠ.3 and GⅡ.2 gastroenteritis occurred in an urban kindergarten in Nanchang,and provide evidence for the response of similar epidemic.Methods Case definitions were developed and case searches were conducted.The epidemiological characteristics and risk factors were analyzed through case investigation and field epidemiological investigation.Samples of anal swab and vomit from the cases and related personnel were collected for norovirus nucleic acid detection with real-time RT-PCR,and the positive samples were sequenced and genetically analyzed.Results A total of 9 patients with the age of around 4 years old were concentrated in one class,with the gender ratio of 2∶1.And the attack rate of the class was47.37%.After cases vomited in the classroom,the nursery governess did not follow standard procedure for disinfection treatment,and she did not transfer the children in the class when handling the vomit.The anal swabs and vomit samples of6 cases were collected and tested by norovirus nucleic acid.The anal swab samples of 3 cases were norovirus GⅡ,1 vomit norovirus GⅡ,1 anal swab sample was norovirus GI,and 3 confidential personnel were tested negative.The results of sequence analysis showed that the pathogens of this outbreak were norovirus GⅠ.3 and GⅡ.2.Conclusions This epidemic was an acute gastroenteritis caused simultaneously by norovirus GⅠ.3 and GⅡ.2 mainly transmitted by aerosol inhalation.After the outbreak occurred in the kindergarten,it should be reported in time,and comprehensive prevention and control measures such as case monitoring,disinfection and isolation should be taken;health education and should also be promoted.