目的 查明一起学校食物中毒的可疑食物、致病因子及感染源,并采取控制措施.方法 主动搜索所有符合病例定义的患者并逐一进行个案调查.采用描述性流行病学方法,分析本次事件病例的流行病学分布特点;采用病例对照研究,在每例病例的同班选择4~5名对照,分析导致本次事件的可疑食物;采集病例、可疑食物、饮用水、食物制作环节、食堂从业人员的标本,进行实验室检测.结果 本次食物中毒的罹患率为5.01%,85.45%的班级有病例发生.病例对照研究发现,是否食用过凉卤菜(OR=2.64,95%CI:1.81~3.85,POR=0.37,95%CI:0.25~0.56,POR值差异有统计学意义.在28名患者的肛拭中检出4株鼠伤寒沙门菌,4株均归入RiboGroup PVUII 515-6-S-1,且相互间相似率>90%,属同一来源菌株.结论 本次疫情的可疑食物为由校外无证作坊制作后在学校食堂售卖的凉卤菜,致病因子确认为鼠伤寒沙门菌,移除可疑食物后,未出现新发病例.
Objective To identify the pathogen and infection source of a food poisoning outbreak in a school and provide evidence for control measures. Methods Case survey, descriptive epidemiological analysis and case control study were conducted. Clinical samples from the cases and food processing people and food/water samples were collected for laboratory detection. Results The attack rate of food poisoning was 5.01%, and the cases occurred in 85.45% of classes in the school. The case control study indicated that the difference in OR of eating cold dish (OR=2.64,95% CI: 1.81-3.85, POR=0.37, 95% CI: 0.25-0.56, PSalmonella typhimurium were detected in the rectal swabs of 4 cases, which shared 90% homology and were classified as Ribo Group PVUII 515-6-S-1. Conclusion S. typhimurium contaminated cold dish was responsible for this food poisoning outbreak. No case occurred after taking appropriate measures.