一起胃肠炎暴发事件流行病学调查

Epidemiological investigation of a gastroenteritis outbreak

目的 分析一起胃肠炎暴发事件的流行特征和发生原因,为类似突发事件处置提供参考。方法2021年9月5日,杭州市某中学暴发一起急性胃肠炎事件,研究人员通过现场流行病学方法收集数据,计算疾病的罹患率,描述其流行病学特征,通过病例对照研究调查可疑食物;采集现患病例肛拭子、可疑人员肛拭子、学校食堂菜品样本、小卖部食品样品,进行实验室病原学检测。结果 在此次胃肠炎暴发事件中,共收集到160例病例,总罹患率为12.58%(160/1 272),临床症状以腹泻[160人(100.00%)]和腹痛[146人(91.25%)]为主,少数伴腹胀[40人(25.00%)]等症状。其中,男性罹患率为17.68%(111/628),女性罹患率为9.63%(49/509),差异有统计学意义(χ^(2)=15.06,P<0.001)。病例对照研究分析未发现可疑食物。实验室检测发现:在17份食堂厨师肛拭子中检出变形杆菌和致泻大肠埃希氏菌各1例;在23份学生病例肛拭子中检出13份肺炎克雷伯菌阳性;在学校食堂可疑食物和小卖部食品样本中均未检出致病菌。在排除食物中毒后,研究人员结合实验室检查结果,怀疑本次胃肠炎事件与饮用水污染有关,当即前往学校采集水样,却得知该校输水管道已于9月8日20:30发生破裂。在学校输水管道破裂而停止供水后,饮用水由直饮水改为瓶装矿泉水,生活用水改由消防车运输,未再发生新病例。结论 此次胃肠炎暴发事件可能是由饮用水被肺炎克雷伯菌污染所引起的,有关部门需加强对学校饮用水日常监测与监督管理。

Objective This study was aimed at analyzing the epidemiological characteristics and causes of a gastroenteritis outbreak,to provide a reference for addressing similar emergencies.Methods On September 5,2021,an outbreak of acute gastroenteritis occurred in a middle school in Hangzhou City.Data were collected through on-site epidemiological methods,the gastroenteritis attack rate was calculated,and the epidemiological characteristics were described.A casecontrol study was conducted to investigate suspicious foods.Anal swabs from people with current gastroenteritis or suspicion of gastroenteritis,and food samples from school canteens and snack counters were collected for laboratory etiology detection.Results In this gastroenteritis outbreak,160 cases were identified,and the overall attack rate was 12.58%(160/1 272).The main clinical symptoms were diarrhea [160(100.00%)] and abdominal pain [146(91.25%)].Rarer symptoms included abdominal distension [40(25.00%)].The attack rate was 17.68%(111/628) in males and 9.27%(49/509) in females,and showed a statistically significant difference(χ~2=15.06,P<0.001).The case-control study did not identify suspicious foods.Laboratory testing of 17 anal swabs from cafeteria cooks identified one case each of Aspergillus sp.and diarrhea-causing Escherichia coli.Of the 23 anal swabs from students with current gastroenteritis,13 were positive for Klebsiella pneumoniae subspecies.No pathogenic bacteria were detected in thesuspected food and snack bar food samples in the schoolcafeteria.After ruling out food poisoning and combining theresults of laboratory tests,the gastroenteritis incident wassuspected to have been associated with contaminated drink-ing water.We immediately sought to collect water samplesfrom the school but found that the school's water pipelinehad ruptured at 20:30 on September 8th.After the school's water pipeline ruptured,and the water supply was stopped,the drinking water was changed from direct-drinking water to bot-tled water,and the domestic water was transported by fire trucks.Since then,no new cases have been reported.Conclusions This outbreak of gastroenteritis might have been caused by the contamination of drinking water with Klebsiella pneu-moniae subspecies.Relevant departments must strengthen daily monitoring and supervision of drinking water in schools.