2018-2019年漳州市诺如病毒暴发疫情的分子流行病学特征

Molecular epidemiological characteristics of norovirus outbreaks in Zhangzhou city from 2018 to 2019

目的分析2018-2019年漳州市诺如病毒暴发疫情的分子流行病学特征。方法选取2018年2月至2019年10月漳州市16起聚集性胃肠炎疫情中的114例疑似病例作为研究对象。收集研究对象粪便、带便肛拭子或呕吐物标本,采用荧光定量PCR方法对标本进行诺如病毒基因检测,GⅡ组阳性样本进一步用普通RT-PCR方法对部分聚合酶区(RdRp)-衣壳区(VP1)进行基因扩增,阳性标本进行测序并做系统进化分析。结果16起聚集性胃肠炎疫情中,11起诺如病毒检测阳性。114例疑似病例中,实验室确诊55例,阳性率为48.25%。其中,GⅡ组48例,GI组1例,GI组和GⅡ组同时阳性的6例;男性40例(72.73%,40/55),女性15例(27.27%,15/55);14岁以下儿童43例,占78.18%(43/55);幼儿园及中小学为主要暴发场所(9/11);季节高峰主要在2-3月及9-12月(10/11)。测序共获得来自8起聚集性疫情中的27份标本序列,系统发育树构建结果显示有4种GⅡ组基因型,包括15株GⅡ.2[P16]、2株GⅡ.4Sydney[P31]、4株GⅡ.17[P17]和6株GⅡ.3[P12]。结论诺如病毒是引起漳州市聚集性胃肠炎的常见病原体,其中GⅡ.2[P16]变异株为本地区优势流行株。

Objective To study the epidemiological and molecular characteristics of the norovirus outbreaks in Zhangzhou city from 2018 to 2019.Methods The 114 suspected cases in 16 acute gastroenteritis outbreaks occurred in the districts and counties of Zhangzhou city from February 2018 to October 2019 were used as research subjects.The fecal samples,anal swab or vomit samples from the cases were collected.Norovirus genes were detected by real-time PCR,and the segments of RNA-dependent RNA polymerase(RdRp)-capsid protein(VP1)of norovirus in the genogroup II(GII)positive samples were amplified by conventional RT-PCR.The positive samples were sent for sequencing and the phylogenetic analyses.Results Eleven outbreaks out of 16 outbreaks were detected positive for norovirus.For the 114 suspected cases,55 were laboratory confirmed with a positive rate of 48.25%,including 48 cases of GII group,1 case of GI group,and 6 cases with co-infections of GI and GII groups.Among the 55 positive cases,40 were males(72.73%,40/55),15 were females(27.27%,15/55)and 43 were children under fourteen years old(78.18%,43/55).The outbreaks mainly occurred in kindergartens and primary schools(9/11),and in the periods of February to March and from September to December(10/11).Sequencing results of 27 samples from 8 outbreaks were obtained.Phylogenetic analysis showed four genotypes of GII group,including 15 strains of GⅡ.2[P16],2 strains of GⅡ.4Sydney[P31],4 strains of GⅡ.17[P17]and 6 strains of GⅡ.3[P12].Conclusions Norovirus was the common pathogen in the gastroenteritis outbreak in Zhangzhou city and GⅡ.2[P16]recombinant strain was the dominant strain.