1起诺如病毒引起的急性胃肠炎暴发调查及实验室检测分析

Epidemiological investigation and laboratory test analysis on an outbreak of acute gastroenteritis caused by norovirus in Shenzhen

目的调查了解1起诺如病毒引起的急性胃肠炎暴发疫情的流行病学特点、传播途径及病原体,为制定预防控制对策提供依据。方法设立病例定义,在深圳市发生疫情的村子进行病例搜索,使用感染性腹泻个案调查表对所有搜索到的病例进行回顾性调查,并分别调查58例病例及74例对照的生活习惯;采用逆转录-聚合酶链反应(RT-PCR)和实时荧光PCR方法分别对病人粪便、肛拭子标本及村民饮用的水样进行诺如病毒核糖核酸(RNA)检测,分析其流行特征及可能传播途径。结果该起疫情首例病例发病时间为2009年10月23日,疫情历时11d,共搜索到97例病例,全村罹患率为9.41%(97/1031),以2岁以下的儿童为多,占53.1%。病例临床症状以腹泻、腹痛、腹胀、恶心、呕吐为主。病例组饮用生的山泉水及就餐前用生的山泉水冲洗碗筷的比例均高于对照组(P<0.05或P<0.01);13份病例粪便和肛拭子标本中,检测出12例诺如病毒阳性,阳性率为92.3%;检测7份水样(包括1份水源水、1份水池水、3份病例家中水龙头水和2份洗碗水),其中2份水龙头水和1份洗碗水检出诺如病毒,其余均为阴性。结论此起群体性胃肠炎暴发疫情是由诺如病毒感染引起;传播途径可能主要因水源污染和生活接触传播所致。

Objective To investigate and reveal the epidemiological characteristics and the mode of transmission of an infectious diarrhea outbreak due to norovirus, and to provide scientific evidence for control strategy development. Methods The case definition was set and the cases were followed up in the village where the epidemic situation happened. All the villagers who met the case definition were interviewed to complete a questionnaire about infectious diarrhea. A case-control study involving fifty-eight cases and seventy-four controls was conducted to explore risk factors and transmission mode. Stool specimens of patients and environmental specimens were collected for test by reverse transcription-PCR and real-time PCR. Results The outbreak lasted eleven days. Ninety-seven cases met the case definition. The onset date of the first case was October 23, 2009. The attack rate in the whole village was 9. 41% （ 97/1 031 ）. The main cases were children aged less than two years old, accounting for 53. 1%. The main symptoms were diarrhea, abdominal pain, abdominal distention, nausea and vomit. In the case-control study, the proportion of villagers drinking raw spring water in case group was significantly higher than that in control group（P 〈0. 05）. The proportion of villagers washing bowls and chopsticks with raw spring water before meals in case group was significantly higher than that in control group（P 〈0. 01 ）. 12 out of 13 excrement specimens and anal swabs had been confirmed positive （92. 3% ） for norovirus. Among seven spring water samples, including one from source, one from tank, three from tap water in patients＇houses and two which were used to wash bowls before sampling, two tap water samples and one bowl-washing water sample was positive for norovirus. Conclusion The gastroenteritis outbreak was caused by norovirus which may transmit through contaminated spring water and contact.