目的 通过对怀宁县一起以诺如病毒感染引起的急性胃肠炎暴发疫情调查分析,探讨疫情暴发的原因和流行病学特征,为制定防控措施提供科学依据。 方法 制定病例定义,开展病例搜索进行流行病学调查,采集病例及有关标本检测,调查疫情暴发危险因素等。 结果 本次疫情累计发病99例,持续时间11d,发病曲线呈单峰带拖尾,发病集中在3月1日至2日,示点源暴露,3月3日以后仍有少量病例不排除因接触传播出现二、三代病例;男性罹患率为0.39%,女性罹患率为0.32%,发病年龄、性别均无显著差异;各村发病率不同,存在统计学差异(χ²=72.469,P＜0.01),管网距离自来水厂越近罹患率越高;饮用该镇水厂自来水人群罹患率0.81%,饮用其它水源人群罹患率0.03%,不同水源人群发病差异有显著性(RR=26.238,χ²=114.692,P＜0.01)。采取病例28份粪便、肛拭子和呕吐物标本中27份诺如病毒核酸阳性,阳性率为96.43%;基因序列分析为诺如病毒GⅡ.17型。结论 本次疫情为一起因自来水受到污染,诺如病毒GⅡ.17型引起的急性胃肠炎暴发疫情,农村地区乡镇自来水厂水源水选址不当、缺乏保护,一旦出现大雨则易造成水源水污染,加之基层自来水厂监管不力是该类事件的危险因素。

Objective To explore the causes and characteristics of an acute gastroenteritis outbreak with the main symptoms of vomiting, abdominal pain, diarrhea, and provide scientific basis for formulating prevention and control measures. Methods Defining the cases and carrying out the epidemiological investigation, collecting the samples of body excretions from cases and dubious water to detect the pathogenic microorganism. Results The cumulative incidence number of this outbreak was 99 cases. The incidence curve of this outbreak showed a single peak tail band and focus on March 1st to second, lasting for 11 days, showing point source exposure. After March 3, there were still a small number of cases. There was no exclusion of the emergence of the two or three generation because of cases of contact.The attack rate of male was 0.39%, and female was 0.32%. There was significant difference in incidence among villages(χ²=72.469,P<0.01), while there was significant difference in incidence among different age groups nor between genders. The closer the pipe network near to the water plant, the higher the attack rate was. The incidence of people drinking running water in the town was 0.81%, drinking other water was 0.03%, and the difference was significant (RR=26.238,χ²=114.692,P<0.01). Among 28 cases of stool, anal swab and vomiting specimens, virus nucleic acid were detected from 27 cases specimens, and the positive rate was 96.43%. Gene sequence analysis showed it was norovirus G typeII.17. Conclusion This epidemic acute gastroenteritis outbreak was due to water pollution of norovirus G type II.17. Improper location of the water source plant in rural areas and lack of protection,a heavy rain and lack of supervision were some risk factors of the event.