2016-2023年南昌市儿童诺如病毒胃肠炎疫情的流行特征及病原学分析

Epidemiological characteristics and etiological analysis of norovirus gastroenteritis outbreaks among children in Nanchang from 2016 to 2023

目的分析2016年3月―2023年2月南昌市诺如病毒(norovirus,NoV)引发儿童胃肠炎疫情的流行特征及基因型别分布,为儿童病毒感染性胃肠炎防控提供科学依据。方法对2016年3月―2023年2月南昌市儿童NoV胃肠炎疫情及个案资料进行流行病学特征分析,采集病例肛拭子、粪便标本或呕吐物,采用实时荧光定量聚合酶链式反应(real-time fluorescence quantitative polymerase chain reaction,RT-PCR)进行NoV GⅠ和GⅡ基因群鉴定,核酸检测阳性标本采用特异引物扩增,所得扩增产物测序后进行基因型别及重组分析。结果共调查处理儿童NoV胃肠炎疫情89起,其中幼托机构49起,小学40起,平均每起疫情涉及14.71例病例,总患病率为3.18%。报告病例男女比为1.22∶1.00,平均流行时间约3 d。疫情高发月份为10月―次年2月,城区幼托机构为疫情高发场所。共采集823份病例样本,NoV核酸阳性率为55.65%。GⅠ群NoV 6起,GⅡ群81起,混合感染2起。73起测序成功,经比对分析出14个基因重组亚型。NoV GⅠ群有GⅠ.3[P13]、GⅠ.6[P11]、GⅠ.4[P4]型;GⅡ群以GⅡ.2、GⅡ.6和GⅡ.7亚型为主,有11个重组亚型。GⅡ群疫情中GⅡ.2[P16]型占比最高,优势基因型由GⅡ.2向其他型别转变。结论南昌市近年儿童NoV胃肠炎疫情主要集中于城区幼托机构,冬季高发。引起疫情的主要病原体是GⅡ群NoV,以GⅡ.2[P16]型为主的多种基因重组型同时流行。

Objective To analyze the epidemiological characteristics and genetic diversity of norovirus gastroenteritis outbreaks among children in Nanchang from March 2016 to February 2023,and to provide scientific basis for the prevention and control of viral gastroenteritis in children.Methods The epidemiological characteristics of norovirus gastroenteritis outbreaks in children were analyzed in Nanchang City from March 2016 to February 2023.Anal swab samples and/or vomits were collected.real-time fluorescence quantitative polymerase chain reaction(RT-PCR)was used to identify norovirus GI and GII genogroups.Specific primers were used to amplify the nucleic acid among positive samples.The amplified products were sequenced and analyzed for genotype and recombination.Results A total of 89 outbreaks of norovirus gastroenteritis in children were investigated during 7 years,including 49 outbreaks in kindergartens and 40 outbreaks in primary schools.The average number of cases involved in each outbreak was 14.71,and the total attack rate was 3.18%.The sex ratio was 1.22∶1.00(male/female),and the average epidemic time was about 3 days.The high incidence month was from October to February of the following year of the total epidemic.Urban childcare institutions were places with high incidence of epidemic.A total of 823 samples were collected,and the positive rate of norovirus nucleic acid was 55.65%.There were 6 outbreaks of GI norovirus,81 outbreaks of GII norovirus,and 2 outbreaks of co-infection.Among them,73 outbreaks were sequenced successfully,and 14 genotypes were identified.The GI norovirus was GⅠ.3[P13],GⅠ.6[P11]P,GⅠ.4[P4].GII norovirus was dominated by GⅡ.2,GⅡ.6 and GⅡ.7 subtypes,with 11 genotypes.GⅡ.2[P16]accounted for the highest proportion,and the dominant genotype changed from GⅡ.2 to other types.Conclusions In recent years,the epidemic of norovirus gastroenteritis in children was mainly concentrated in urban kindergartens,and winter was the high incidence season in Nanchang.The main pathogen was GII norovirus,with multiple gene recombination types mainly GⅡ.2[P16]circulating at the same time.