南宁市某公司因蓄水池被诺如病毒污染引起急性胃肠炎暴发调查

目的 对H公司1起诺如病毒感染引起的急性胃肠炎暴发开展调查，分析感染原因和传播途径。方法 根据病例定义开展病例搜索，对供水系统进行卫生学调查，对危险因素进行病例对照研究，采集病例肛拭子、自来水、桶装水进行诺如病毒核酸检测。结果 疫情历时4d，共搜索到病例184例，罹患率10.09%（184/1823）；临床症状主要为腹泻（100%）、腹痛（65.76%）、恶心（50.07%）、呕吐（50.35%）、发热（40.21%）；市政供水进入蓄水池A、B前余氯为0.17mg/L，浊度正常；蓄水池A供应的综合楼6楼和18楼末梢水浊度分别为11.7NTU和11.5NTU，有臭味，余氯均为0mg/L；4份现症病例肛拭子和5份蓄水池A样品均检出GⅡ型诺如病毒，而桶装水和蓄水池B均未检出。食用蓄水池A水洗过的水果和用蓄水池A水洗杯子后装桶装水喝是急性胃肠炎发病的危险因素（OR=6.295，95%CI:4.018~9.862；OR=2.665，95%CI:1.424~4.987）。结论 本次急性胃肠炎暴发是由于污水管道堵塞导致生活饮用水受诺如病毒污染引起的，应加强饮用水卫生管理。

An outbreak of acute gastroenteritis caused by a Norovirus contaminated water reservoir in a company,Nanning City

Objective To investigate an acute gastroenteritis outbreak caused by norovirus infection in H Company, and to analyze the causes and the way of spreading. WTHZ]Methods WTBZ]Case search was carried out according to the case definition. A hygienic survey was conducted on the water supply system. A case-control study was applied to find out risk factors. Norovirus nucleic acid detection was utilized on anal swabs of infected people, tap water and bucket water samples. WTHZ]Results WTBZ]The outbreak lasted 4 days, and 184 cases were found. The attack rate was 10.09% (184/1823). Clinical symptoms were mainly diarrhea (100%), abdominal pain (65.76%), nausea (50.07%), vomiting (50.35%) and fever (40.21%). Before the municipal water entering Reservoir A and B in H Company, the residual chlorine level of the water was 0.17 mg/L, and the turbidity was normal. The turbidities of the terminal water from the 6th and 18th floors of the comprehensive building supplied by Reservoir A were 11.7 NTU and 11.5 NTU, respectively. It had a bad smell and the residual chlorine was 0 mg /L. Norovirus GII was detected in 4 anal swabs of ongoing cases and 5 water samples supplied by Reservoir A, but not detected in either barrel water or Reservoir B water samples. The behaviors of eating the fruits washed by the water from Reservoir A and drinking bucket water with the cups washed by the water from Reservoir A were risk factors for acute gastroenteritis (OR=6.295, 95%CI: 4.018~9.862; OR=2.665, 95%CI: 1.424~4.987). WTHZ]Conclusion WTBZ]The outbreak of acute gastroenteritis was caused by norovirus contaminated drinking water due to the blockage of sewage pipeline. Double efforts should be given to drinking water hygiene management.