一起工厂伤寒爆发疫情的流行病学调查与分析

目的探讨伤寒疫情的规模及原因,以便及时采取科学、合理的疫情控制措施。方法采用病例对照研究方法开展此次疫情调查,比较病例与对照之间不同危险因素的暴露比例,并采集工厂内外环境、饮食及水源的相关样本进行检测。结果共报告28例伤寒确诊病例,无死亡。对病例中分离的12株伤寒菌株进行的PFGE检测结果一致。病例分布在该片区217间工厂中的10间,平均罹患率为3.1‰,工厂间的罹患率无统计学意义（χ^2=5.2,P=0.74）。在危险因素的单因素及多因素分析中,病前外出进餐史（OR=8.0,95%CI：2.6～25）、病前凉面或凉皮进食史（OR=6.8,95%CI：1.4～32）及直接引用生水史（χ^2=4.9,P〈0.01）等危险因素结果一致,均有统计学意义。在所有40份环境样本中,水箱水、井水及水箱底泥水均发现有粪大肠菌群超标现象,但未分离到伤寒沙门氏菌。结论此宗伤寒可能是由于饮用污染的井水和在凉面、凉皮制作过程中使用污染井水导致的。采取加强饮食卫生管理、隔离治疗病人及带菌者、停止使用井水而改用市政供水等措施之后疫情终止。

Investigation and Analysis on A Typhoid Fever Outbreak in Factory Workers

Objective To investigate the extent and cause of the typhoid fever （TF） outbreak and provide a scientific basis for control measures. Method We have done a case-control study on the TF outbreak and compared the cases with control on the exposure to risk factors. We collected information concerning the general public health environment inside and outside the factory, and food and drink samples. Result We identified 28 cases from this TF outbreak and no case died. Salmonella typhi （ST） isolated from 12 cases had identical PFGE patterns. Cases were widely distributed among 10 of the 217 factories. The average attack rate was 3.1%o and the attack rate had no significant difference between factories （χ^2=5.2, P=0.74）. In the single factor analysis and multiple factors analysis showed there were 3 risk factors which had significant differences between cases and controls. The 3 risk factors were eating meals outside （OR=8.0, 95%CI： 2.6-25）, eating cold noodle （OR=6.8, 95%CI. 1.4-32） and drinking tap water directly without boiling （χ^2=4.9, P〈 0.01 ）. We isolated fecal coliform bacteria but no ST from well water samples, samples of bottom mud, and water samples from the water tank in factories. Conclusion This TF outbreak probably resulted from contaminated well water and from cold noodles rinsed with that water. In addition to general sanitation measures and treatment of patients, we ceased well water supply and substituted it with local municipal water and none new case was then occurred.