北京市西城区2017—2022年学校诺如病毒疫情流行特征及基因分型

Epidemiological characteristics and genotype of norovirus outbreaks in schools in Xicheng District of Beijing from 2017 to 2022

目的分析2017—2022年北京市西城区学校诺如病毒疫情流行病学及分子分型特征,为预防和控制学校诺如病毒疫情提供依据。方法分析整理北京市西城区2017—2022年学校诺如病毒感染疫情资料,采用描述性流行病学方法和χ^(2)检验进行统计分析,实时荧光PCR方法检测GⅠ、GⅡ组诺如病毒核酸,诺如病毒核酸阳性标本送北京市疾病预防控制中心进行分子分型鉴定。结果2017—2022年北京市西城区报告诺如病毒疫情185起,聚集性疫情166起,暴发疫情19起。涉及病例2044例,总罹患率13.92%。疫情发生时间存在2个高峰,分别为春季3—6月及秋季10—12月。小学是最主要的发生场所(101起),其次为托幼机构(68起)和中学(16起);不同场所之间罹患率差异有统计学意义(12.37%,22.78%,8.47%,χ^(2)=263.34,P<0.01)。呕吐、腹泻、恶心、腹痛症状在不同学段人群中发生率差异均有统计学意义(χ^(2)值分别为263.33,90.58,20.42,30.29,P值均<0.01)。小学及托幼儿童以呕吐为主要表现(96.41%,98.28%),中学生腹泻比例较高(68.22%)。GⅡ型诺如病毒是引起疫情主要的病原体,2017—2021年整体呈现以GⅡ.2[P16]基因型为主,基因型分布多样性的特点,但2019—2021年GⅡ.2[P16]基因型无明显优势。结论小学及托幼机构是诺如病毒疫情发生的主要场所,诺如病毒疫情主要由GⅡ型引起,GⅡ.2[P16]为优势基因型。应针对重点人群,提高识别早期症状能力,持续加强传染病管理,积极落实消毒等各项防控措施,同时加强疫情及散发病例病原学监测。

Objective To analyze the epidemiological and molecular characteristics of norovirus outbreaks in schools in Xicheng District of Beijing from 2017 to 2022,so as to provide evidence for the prevention and control of norovirus outbreaks in schools.Methods Data of norovirus outbreaks in schools in Xicheng District,Beijing during 2017 to 2022 were collected and analyzed by descriptive epidemiological methods.Real-time PCR was used to detect the nucleic acid of group GⅠand GⅡnorovirus,the positive norovirus nucleic acid samples were sent to Beijing Center for Disease Control and Prevention for molecular typing.Results From 2017 to 2022,185 norovirus outbreaks were reported in schools in Xicheng District,including 166 cluster outbreaks and 19 outbreaks.A total of 2044 cases were reported,with a total attack rate of 13.92%.There were two peaks in the outbreak time,which were from March to June after the spring semester and from October to December after autumn semester.Primary schools were the most common place of occurrence(101 cases),followed by nursery institutions(68 cases)and secondary schools(16 cases).There were statistically significant differences in the incidence rates among different sites(12.37%,22.78%,8.47%,χ^(2)=263.34,P<0.01).There were significant differences in the incidence of vomiting,diarrhea,nausea and stomachache among different students(χ^(2)=263.33,90.58,20.42,30.29,P<0.01).Vomiting was the main symptom in primary school and nursery school children(96.41%,98.28%),and the diarrhea rate was higher in middle school students(68.22%).The outbreaks were mainly caused by type GⅡnorovirus.The genotype from 2017 to 2021 showed the characteristics of diversity,mainly GⅡ.2[P16],but there was no significant advantage for the GⅡ.2[P16]during 2019 to 2021.Conclusions The norovirus outbreak in schools in Xicheng district of Beijing from 2017 to 2022 are mainly caused by GⅡtype genome.The main genotype is GⅡ.2[P16].Norovirus infection mainly occurred in primary schools and kindergartens.For the vulnerable populations,it is necessary to improve the capacity to early identification,student infectious disease management,active infection control and prevention measures,and pathogen surveillance and sporadic case monitoring.