一起诺如病毒Ⅰ型Ⅱ型混合感染急性胃肠炎暴发疫情调查分析

目的 对湖州市某中学发生的一起以腹泻、呕吐为特征的暴发疫情进行调查和分析,查找病因、分析危险因素.方法 采用现场流行病学调查方法,结合临床表现及实验室检测结果进行调查与综合分析.结果该校共发生急性胃肠炎病例578例,罹患率为23.58%;临床表现主要为腹泻、呕吐、腹痛、恶心,少见发热,大多症状较轻,病程1～3 d;各班均有发病,无明显聚集性;共采集患者粪便标本15份,采用RT-PCR方法检出诺如病毒阳性标本11份,其中Ⅱ型6份,Ⅰ型阳性3份,Ⅰ型、Ⅱ型混合阳性2份(同一学生,两次采样).病例对照研究显示,饮用未加热桶装水是此次发病的危险因素(OR=2.46,95% CI=1.19～5.23),且饮水量与发病存在剂量反应关系(X2=24.18,P<0.01).通过采取隔离治疗传染源、改桶装水为供应开水、卫生消杀及健康教育等综合措施后,疫情迅速得到控制.结论 本次疫情是由诺如病毒引起的急性胃肠炎暴发,可疑的传播途径为饮用未加热的桶装水与日常接触.

An investigation and analysis on an outbreak of acute gastroenteritis caused by gcuogroup Ⅰ and Ⅱ norovirus

Objective To investigate the cause of an outbreak characterized by diarrhea and vomit in a middle school in Huzhou City. Methods Comprehensive analysis was conducted based on field epidemiological study, clinical characteristics of the cases and laboratory test. Results 578 cases of acute gastroenteritis were found. The attack rate was 23.58%. The most frequently observed clinical symptoms were diarrhea, vomiting,abdominal pain and nausea. Some few had fever. Most cases had slight clinical symptom with a course from 1 to 3 days. The cases were distributed in every class, showing no phenomenon of clustering. Norovirus were detected in 11 out of 15 stool samples by using RT-PCR. 6 were genogroup Ⅱ norovirus. 3 were genogroup Ⅰ norovirus.Genogroup Ⅰ and Ⅱ norovirus were detected at the same time in 2 stool samples (the same student with 2 tests).Case-control study showed that drinking unheated bottled water was risk factor(OR=2.46,95% CI = 1.19-5.23),and had a dose response relation with the disease(X2=24.18, P<0.01). The epidemic was controlled soon through isolating patients during treatment, providing boiled water, disinfecting and health education. Conclusion This was an infectious diarrhea outbreak caused by norovirus. The suspected transmission ways were drinking unheated bottled water and contact daily.