兰州市某小学一起诺如病毒感染聚集性疫情流行病学调查

Epidemiological investigation on an outbreak of Norovirus infection at a primary school in Lanzhou

目的对甘肃省兰州市某小学发生的一起急性胃肠炎聚集性疫情开展流行病学调查,为今后预防和控制此类聚集性疫情提供参考。方法通过制定病例定义、开展病例搜索、调查病例发生情况和可疑传播途径、采集生物和环境标本、以RT-PCR方法检测肠道病毒核酸等方法,对2018年5月29日兰州市某小学发生的急性胃肠炎聚集性疫情开展流行病学调查和分析。结果共搜索到疑似病例27例、确诊8例,罹患率4.8%(35/736);病例临床表现以呕吐(88.6%)和恶心(62.9%)为主,流行曲线提示疫情呈现人传人模式发病特点,校内接触病例是发病危险因素(OR=4.9,95%CI:1.2~19.5);8例病例肛拭子和处理首发病例呕吐物的簸箕标本中均检出诺如病毒GⅠ型核酸。结论本次疫情为一起学校发生的GⅠ型诺如病毒感染引起的急性胃肠炎暴发;首发病例感染诺如病毒后,在学校内呕吐污染周围环境,其他学生通过与病例接触或接触呕吐物污染的环境,导致聚集性疫情发生。

Objective To carry out epidemiological investigation on a clustering epidemic of acute gastroenteritis at a primary school in Lanzhou city,so as to provide reference for preventing and controlling similar epidemic in future.Methods Epidemiological survey and analysis were conducted for the clustering epidemic of acute gastroenteritis at a primary school in Lanzhou city by formulating case definition,developing patient screening,investigating disease occurrence and route of transmission,collecting biological and environmental samples and detecting for nuclear acid of enterovirus with RT-PCR during the prevalence on May 29,2018.Results Totally there were 27 suspected cases found and 8 cases confirmed,with incidence rate of 4.8%(35/736).Emeses(88.6%)and diarrhea(62.9%)were the main clinical symptoms.The epidemiological curve showed the epidemic characteristics of human to human mode,and case contact within the school was the risk factor(OR=4.9,95%CI:1.2-19.5).The gene type of GⅠof Norovirus was confirmed in anal swabs of the 8 patients and the vomit samples of the first patient collected from dustpan.Conclusions The epidemic is an acute gastroenteritis outbreak caused by GⅠtype of Norovirus infection at the school.The students are infected by contacting the patient or the environment polluted by the vomit of the first patient.