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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 investigate the outbreak of acute gastroenteritis caused by norovirus infection in Huaining County and to investigate the causes and epidemiological characteristics of the outbreak and provide a scientific basis for the development of prevention and control measures. Methods To define the case, carry out epidemiological investigation on case search, collect cases and relevant specimens, and investigate the risk factors of outbreaks. Results The cumulative incidence of 99 cases of this epidemic, the duration of 11d, the incidence curve was single peak tailing, the incidence concentrated in the March 1 to 2, showing point source exposure, after March 3 there are still a small number of cases do not rule out There was no significant difference in the age of onset and sex between the two groups (χ2 = 72.469, P <0.01). There was no significant difference in incidence between the two groups (χ2 = 72.469, P <0.01) , The closer the pipe network is from the water plant; the attack rate is 0.81% in drinking tap water and 0.03% in drinking other drinking water sources, and there is significant difference among different water sources (RR = 26.238, χ2 = 114.692 , P <0.01). Twenty-seven cases of norovirus positive samples from 28 stool samples, anal swabs and vomit samples were positive, with a positive rate of 96.43%. The sequence analysis was Norovirus GⅡ.17. Conclusions The outbreak was caused by polluted tap water and the outbreak of acute gastroenteritis caused by Norovirus GⅡ.17. The water supply of township waterworks in rural areas was sited inappropriately and lacks protection. In the event of heavy rain, it was easy to cause water pollution , Combined with poor supervision of grass-roots waterworks is a risk factor for such incidents.