1起接触传播引起的小学诺如病毒暴发调查

Survey on an outbreak of norovirus caused by person to person contact in a primary school

目的为查明1起小学诺如病毒暴发疫情的传播途径和危险因素并采取适宜的防控措施。方法采用现场调查的方法了解学生饮水、饮食和接触等信息;对6个班级的263名学生进行回顾性队列调查,比较不同暴露的罹患率。采集肛拭子、呕吐物以及食物进行检测。结果共搜索到病例87例(疑似病例78例、确诊病例9例),教职工病例1例,罹患率为7.85%。女生总体罹患率(9.11%)与男生(6.72%)无统计学差异(P>0.05)。32.94%的病例呕吐次数≥5;首例病例病毒携带时间>7d。接触病例的罹患率为38.24%,高于未接触病例的罹患率24.05%(RR=1.67,95%CI:1.10~2.55)。在教学楼3层的10个教室中,发病的6个班级就餐时共用同一通道,而未发病的4个班级共用对侧通道。有实验室检测1名厨工和9名病例、3名非病例肛拭子检测出诺如病毒阳性。结论这是1起由人-人接触传播引起的诺如病毒暴发疫情,接触病例是危险因素。未严格隔离病人、消毒不规范导致疫情扩散。

Objective To identify the risk factors,outbreak source,and take proper measures to control the outbreak associated with norovirus in a primary school. Methods Field investigation was performed to learn about the information of food and water consumption and contact history.a retrospectively cohort study was conducted among 264 students from six affected classes,compare their attacked rates caused by different exposures.Residual food,the vomited matter and anal swab were collected for testing. Results A total of 87 cases（78 susceptible cases,9 confirmed cases）and 1 teacher was reported with attacked rate of 7.85%.The attacked rate of female（9.11%）had no statistical difference from male（6.72%）（P〉0.05）.Cases whose vomits times were equal or greater than five times accounted for 32.94%.The first case carried virus for up to 7 days.The attacked rate who closely contacted with cases was 38.24%,compared 24% who had not（RR =1.67 95%CI ：1.10-2.55）.Out of the 10 classes on the third floor,the affected 6 classes shared the same entrance to the canteen,and unaffected 4 classes shared another on the opposite.One food worker,nine cases,three asymptomatic students were tested positive respectively. Conclusion This outbreak is transmitted by people to people,closely contacting with cases is the risk factor.Failure to isolate patients for sufficient time,impertinent disposal of vomitus are contributed to the spread of the outbreak.