2018学年上海市闵行区校园诺如病毒感染引起的聚集性疫情传播特征分析

Analysis on characteristics of norovirus infectious outbreaks in campus of Minhang District in Shanghai during 2018 academic year

目的了解2018年上海市闵行区中小学校和托幼机构诺如病毒感染引起的聚集性疫情的流行特征和传播特点,为进一步做好校内诺如病毒引起的聚集性呕吐腹泻疫情防控提供参考依据。方法收集2018学年上海市闵行区托幼机构和中小学校发生的聚集性呕吐腹泻疫情调查报告和相关资料,分析诺如病毒感染引起的疫情的流行特征、疫情动力学特征和传播途径。结果2018学年上海市闵行区409所托幼机构和中小学校共发生诺如病毒感染的聚集性呕吐腹泻疫情26起,GⅡ型为主,占92.31%,病例235例,平均罹患率为23.55%。发病时间以3、10和11月为主,病例以小学和托幼机构儿童为主,共214例,占91.06%,病例临床症状以呕吐为主,共229例,占97.45%,托幼机构与中心学校呕吐、腹泻、发热、恶心发生率比较,差异均无统计学意义(均P>0.05);病例肛拭子样本数为99份,阳性率为75.76%,班级密切接触者和教室、厕所等环境样品表面阳性率分别为11.32%(6/53)和1.01%(2/199)。疫情规模范围为3~33例/起,平均为9.04例/起,首发病例发生24 h内报告的疫情占73.08%,疫情持续时间平均为1.31天,平均增长速度为6.69例/天,平均基本再生数为7.62,基本再生范围为3.00~32.00,幼儿园罹患率高于中小学校,差异有统计学意义(P<0.05),平均基本再生数比较差异无统计学意义(P>0.05),点源传播和首发病例传播引起的疫情平均再生数比较差异无统计学意义(P>0.05)。疫情传播途径均为人传人,以密切接触传播为主。结论2018学年上海市闵行区校园发生的聚集性呕吐腹泻疫情以诺如病毒感染为主,罹患率较高,基本再生数较高。中小学校和托幼机构对首发病例的现场处置规范,一定程度上防止了疫情扩散,需常抓不懈。

Objective To understand the epidemic and transmission characteristics of outbreaks caused by norovirus infection in primary and secondary schools and childcare institutions of Minhang District in Shanghai in 2018,provide scientific evidence for the further prevention and control of aggregated vomiting and diarrhea caused by norovirus in campus.Methods The investigation report and related data on the outbreak of vomiting and diarrhea occurred in childcare institutions and primary and secondary schools in Minhang District in the academic year 2018 were collected and summarized.Epidemic characteristics,epidemic dynamics and transmission routes of the epidemic caused by norovirus were analyzed.Results Totally 26 norovirus caused vomiting and diarrhea outbreaks occurred in 409 childcare institutions and primary and secondary schools in Minhang District in the 2018 academic year.The predominant strain belonged to GⅡtype,accounting for 92.31%.There were 235 cases,and the attack rate was 23.55%.March,October and November were the months with high incidence.The cases were mainly primary school students and kindergarten children(214 cases,91.06%).The main clinical manifestations were vomiting(229 cases,97.45%).The differences in the detection rates of symptoms of vomiting,diarrhea,fever and nausea between childcare institutions and schools were not statistically significant(P>0.05).There were 99 positive anal swab samples of patients,with the positive rate of 75.76%.The positive rate of close contacts of the class and the surfaces of environmental samples such as classrooms and toilets was 11.32%(6/53)and 1.01%(2/199)respectively.The epidemics usually affected 3 to 33 cases,with an average of 9.04 cases.Outbrea ks reported within 24 hours of the first case occurred accounting for 73.08%.The average duration of the outbreaks was 1.31 days,and average growth rate was 6.69 cases/day.The mean of the basic reproductive number was 7.62,and the basic reproductive range was 3.00-32.00.The prevalence rate in childcare institutions was higher than that in primary and middle schools,and the difference was statistically significant(P<0.05),and there was no statistically significant difference in the average basic reproductive number(P>0.05).The difference was not statistically significant in the average basic reproductive number between the outbreaks caused by point source transmission and first case transmission(P>0.05).The transmission routes of all outbreaks were human to human,which mainly was close contact transmission.Conclusion The epidemic of clustered vomiting and diarrhea in campus of Minhang District in Shanghai during 2018 academic year is mainly caused by norovirus infection,with a high attack rate and a high basic reproductive number.Schools and childcare institutions have standardized the on-site treatment of the first case,which has prevented the spread of the epidemic to some extent.These measures need to be constantly pursued.