调查南京市两所高校细菌性痢疾暴发的传染来源、传播方式和波及范围。

本研究以2015年9月7日至10月8日南京市两所高校细菌性痢疾疑似、可能和确诊患者为研究对象。定义疑似患者为两所高校学生、教职工中出现腹泻症状者；可能患者为疑似患者且出现发热(T≥37.4℃)、里急后重或腹痛症状之一者；确诊患者为疑似或可能患者且粪便或肛拭子标本PCR检测志贺氏菌核酸片段阳性或分离到志贺氏菌者。收集两所高校的一般情况；通过该区医疗机构、校卫生所和辅导员报告的方式进行患者搜索，对患者进行个案调查并描述病例一般情况、临床表现、分布特征；开展患者对照研究；调查可疑餐次和食物，对患者和食堂从业人员采集大便或肛拭子标本以及环境和食物留样标本行核酸片段聚合酶链式反应(PCR)检测沙门氏菌和志贺氏菌，运用脉冲场凝胶电泳(PFGE)对分离的菌株进行同源性分析。利用描述流行病学方法描述病例时间、空间和人群分布特征，罹患率差异用χ²检验，病例对照研究中计算可疑餐次的OR值及95%可信区间(CI)。

A、B高校分别搜索到436例和36例病例，罹患率分别为2.6%(436/15385)和0.23%(36/15449)，流行曲线提示点源暴露；A高校住校生罹患率高于走读生[2.9%(434/15027) vs 0.78%(2/258), χ²＝4.09，P<0.05]，南宿舍区罹患率高于北宿舍区[4.6%(351/7 666) vs 1.1%(83/7361), χ²＝159.46，P<0.001]。病例对照研究显示A高校可疑餐次为9月20日晚餐(OR＝2.4，95%CI为1.2～4.7)；两所高校患者和相关食堂从业人员肛拭子标本中分离到10株宋内氏志贺氏菌Ⅰ型菌株，PFGE检测结果显示高度同源。

本次疫情为一起宋内氏志贺氏菌引起的食源性细菌性痢疾暴发，波及两所高校，应继续加强食源性疾病监测和学校、集体单位食堂的卫生管理和监督。

To investigate the source, transmission mode and infection range of the bacterial dysentery outbreak in two colleges in Nanjing.

Suspected cases were defined as students and staff members in these two colleges with the symptoms of diarrhea during the period from September 7 to October 8, 2015. Probable cases were defined as suspected cases with one of the three symptoms: fever(T≥37.4℃), tenesmus, or abdominal pain. Confirmed cases were defined as suspected or probable cases with PCR detection for Shigella DNA fragment positive in fecal or anal swab specimens or with isolated Shigella. The general situation of these 2 colleges was investigated. We conductedactive case searching by reporting from local medical institutions, college health center and counselors; conducted case study and describing general information, clinical manifestations, and distribution features; conducted matched case control study for suspicious meals and food; collected stools or rectal swab specimens of cases and food handlers, environmental samples and food retention samples to test Salmonella and Shigella by PCR; used PFGE for analysis of homology of the isolated strains; analyzing the distribution of cases by descriptive epidemiology method andthe difference of attack rates by Chi-square test, and calculate Odds ratios (OR) with 95 % confidence intervals (CI) of suspicious meals in case control study.

A total of 436 and 36 cases were found out in collage A and B, leading to attack rates of 2.6% (436/15 385) and 0.23% (36/15 449) respectively and the epidemic curve indicated a point source exposure. In collage A, the attack rate of boarders was higher than that of day students (2.9%, 434/15 027 vs 0.78%, 2/258, χ²=4.09, P<0.05); the attack rate of the students lived in the south dormitory area was higher than that in the north area (4.6%, 351/7 666 vs 1.1%, 83/7 361), χ²=159.46, P<0.001). The case control study result showed that the suspicious exposure meal was dinner on September 20(OR=2.4, 95%CI: 1.2-4.7). Shigella sonnei strain I was isolated from anal swab specimens of cases and canteen employees in these two colleges, and the PFGE detection results showed a high degree of homology.

This is a bacterial dysentery outbreak caused by Shigella sonnei involving two colleges in Nanjing. We should continue to enhance the surveillance of foodborne disease and sanitary control and supervision of canteens in schools and other collective units.