一起幼儿园诺如病毒暴发疫情调查及分子流行病学特征分析  

Investigation of a norovirus infection outbreak in a kindergarten and analysis on pathogen molecular epidemiological characteristics

作　　者：张辉[1] 李倩[1] 唐红 刘继锋[1] 李思瑶 李焱[1] Zhang Hui;Li Qian;Tang Hong;Liu Jifeng;Li Siyao;Li Yan(Xi′an Center for Disease Control and Prevention,Xi′an 710054,Shaanxi,China)

机构地区：[1]西安市疾病预防控制中心,陕西西安710054

出　　处：《疾病监测》2022年第6期844-849,共6页Disease Surveillance

基　　金：陕西省2020年自然科学基础研究(No.2020JQ-969)。

摘　　要：目的 调查2021年西安市一起幼儿园诺如病毒暴发疫情的流行特征和暴发原因,并对病原体进行分子鉴定分型。方法 根据诺如病毒疑似病例定义主动搜索病例,同时开展现场卫生学调查;采用描述性流行病学方法描述病例的临床症状和三间分布特征,结合队列研究方法分析疫情暴发原因;采集典型病例肛拭子样本进行诺如病毒核酸检测和基因测序分型。结果 该起暴发疫情共持续3 d,累计报告病例31例,病例均为幼儿,罹患率为14.16%(31/219),其中4岁病例占比最大(93.55%,29/31),小(4)班罹患率最高(40.00%,12/30);病例临床症状主要为呕吐(100%)、腹泻(12.90%)和腹痛(6.45%),无重症和死亡病例。流行曲线提示疫情为一次性暴露后同源感染引起。队列研究显示近距离暴露呕吐物幼儿发病风险是远距离暴露幼儿的3.98倍(相对危险度=3.98,95%置信区间:2.159~7.334)。病例样本诺如病毒阳性检出率为61.54%(8/13),经基因测序和鉴定分型确定渉疫毒株为GⅡ.3[P12]基因型诺如病毒。结论 该起疫情暴发原因是托幼儿童暴露于首发病例呕吐物形成的气溶胶,感染毒株为GⅡ.3[P12]基因型诺如病毒。建议托幼机构加强教职工诺如病毒疫情防控知识培训,尤其是对病例呕吐物和排泄物的应急处置,防止类似疫情再次发生。Objective To investigate the epidemiological characteristics and identify the cause of a norovirus infection outbreak in a kindergarten of Xi′an in 2021, and the pathogen was identified by molecular typing. Methods Active case finding was carried out according to the definition of suspected norovirus cases, and field hygienic survey was conducted. The clinical manifestations and the distribution of the cases were described with descriptive epidemiological method, and cohortstudy was used to find out the cause of this outbreak. Anal swab samples were collected from typical cases for norovirus nucleic acid detection and gene sequencing. Results This norovirus outbreak lasted for 3 days, and a total of 31 cases were reported, all the cases were children, with an average attack rate of 14.16%(31/219). Among them, the cases aged 4-year-old accounted for the highest proportion(93.55%, 29/31), and the class 4 of grade 1 had the highest attack rate(40.00%, 12/30).The main clinical symptoms were vomiting(100%), diarrhea(12.90%) and abdominal pain(6.45%). No severe cases or deaths were reported. The epidemic curve showed that the outbreak was caused by one-time same source exposure. The cohort-study showed that the risk of close exposure to vomit was 3.98 times higher than that of long-distance exposure(RR=3.98, 95%CI:2.159–7.334). The positive rate of norovirus in case samples was 61.54%(8/13). Gene sequencing and type identification indicated that the pathogen was norovirus GⅡ.3[P12]. Conclusion This outbreak was caused by the exposure to aerosols from vomit of the index case, and the pathogen was norovirus GⅡ.3[P12]. It is necessary to strengthen the training of staff in child care settings on norovirus prevention and control, especially on emergency disposal of excreta and vomit, to prevent such epidemics.

关 键 词：诺如病毒 GⅡ.3[P12]基因型 暴发 流行病学 重组 

分 类 号：R211[医药卫生—中医学] R373.9