1起肠炎沙门菌引起学校食源性疾病暴发事件的流行病学调查

Epidemiological investigation of foodborne Salmonella enteritidis outbreak in a school

目的调查分析1起学校食源性肠炎沙门菌暴发事件的危险因素,提出控制及预防措施。方法采用描述性流行病学方法对该起事件的流行特征进行分析;采用病例对照研究方法进行可疑食物的调查;采集部分病例、厨工肛拭子和环境拭子样本进行病原菌的分离、血清学分型鉴定和脉冲场凝胶电泳分析。结果该起食源性疾病暴发首发病例发病时间为2009年6月9日,末例病例发病时间为6月12日,事件历时4 d,流行曲线提示该次事件符合点源暴发模式。共报告病例61例,均为寄宿生,走读生和教职工均无发病,其中男寄宿生发病12例,罹患率为3.9%(12/309),女寄宿生发病49例,罹患率为10.7%(49/460),女生的罹患率明显高于男生(P<0.01)。病例对照研究结果提示,6月9日早餐的鸡蛋三文治为引起发病的危险食品(OR=21.70,95%CI为8.50～55.50)。采集患者肛拭子25份、食堂厨工肛拭子14份、食堂冰箱和环境拭子11份,分别有19、5、1份样本检出同一血清型的肠炎沙门菌;脉冲场凝胶电泳法分析结果表明该25株肠炎沙门菌分离株具有完全相同的PFGE图谱。结论该事件为1起肠炎沙门菌污染食物引起的食源性疾病暴发事件,可疑中毒食物为6月9日早餐的鸡蛋三文治,卫生监管部门应重视对各类以鸡蛋为原料的食品的卫生监督。

Objective To find out the risk factors of Salmonella outbreak in a school,and to put forward prevention and control measures. Methods Descriptive epidemiology study was performed to survey the basic hygiene conditions of the school. Case-control study was conducted to investigate the suspected meal and food through questionnaires. Specimens from patients,culinary workers,residual foods and environment samples were collected for pathogenic isolation,serotype and pulsed field gel electrophoresis（ PFGE） molecular classification. Results First case＇s onset date was June 9 and last case＇s was June 12. The outbreak lasted 4 days. Epidemiological curve suggested that it be a point source outbreak. A total of 61 cases were identified and were all boarding students,including 12 males and 49 females. The incidence of female（ 10. 7%,49 /460） was significantly higher than that of males（ 3. 9%,12 /309）（ P 0. 01）. Case-control study indicated that the egg sandwich of breakfast on June 9 was the risk factor to cause this outbreak（ OR = 21. 70,95% CI： 8. 5055. 50）. A total of 25 strains of Salmonella enteritidis were isolated and identified,of which 19 were from anal swabs of 25 patients,5 from anal swabs of 14 canteens kitchen staff,and 1 from 11 swabs of refrigerator handles,respectively. PFGE analysis showed that all the 25 strains had the same PFGE type. Conclusion This was a foodborne disease outbreak caused by Salmonella enteritidis and the risk factor was egg sandwich of breakfast. Health supervision and inspection authorities should pay much attention to all kind of food with eggs as the raw material.