一起由GⅡ.17型诺如病毒引起的食源性疾病暴发调查

Investigation of an outbreak of foodborne illness caused by norovirus GⅡ.17

目的查明2018年北京市某研究所急性胃肠炎聚集性病例的发生原因和致病因素。方法通过描述性流行病学方法描述病例的临床表现和三间分布,结合病例对照研究结果查找可疑暴露餐次和可疑致病食品。开展现场卫生学调查,采集病例标本和食品加工工具涂抹样本进行诺如病毒PCR检测和基因序列测定。结果共搜索到107例病例,症状主要为腹泻(100%)、腹痛(79%)、呕吐(74%)和恶心(68%)。现场流行病学调查结果显示,可疑暴露餐次为3月21日午餐(由某送餐公司供餐),可疑致病食品为酱肘子,酱肘子在加工过程中存在交叉污染的可能且食用前未经有效加热是可能的感染环节。在26份粪便/肛拭子样本中检出17株GⅡ型诺如病毒株,基因测序发现,8株聚合酶区核苷酸序列100%一致,经比对与GⅡ.17型变异株41 621同源性达99%。结论食用了被诺如病毒污染的酱肘子是导致本次食源性疾病暴发的主要原因,建议加强对餐饮单位的监督管理,使其形成良好的生产操作规范,防止类似事件再次发生。

Objective To find out the cause and pathogenic factors of acute gastroenteritis occurred in a research institute in Beijing, 2018. Methods The clinical manifestations and the distribution of the patients were described with descriptive epidemiological method, and case control study was used to find out the suspected exposed meals and foods. Field hygiene survey was carried out. Samples from the cases and foods were collected for the PCR detection of norovirus, and partial gene sequencing of RNA-dependent RNA polymerase region was performed for the positive strains. Results A total of 107 cases were found with the main symptoms of diarrhea(100%), abdominal pain(79%), vomiting(74%) and nausea(68%). The results of the epidemiological investigation demonstrated that the lunch of March 21(provided by a food delivery company) was the suspected meal, and sauce elbow was the suspected food, which might be cross-contaminated during the preparation and without effective heating before provision. Seventeen strains of norovirus GⅡ were detected from 26 anal swabs and stool samples. Polymerase region gene sequencing showed that 8 strains shared 100% consistent nucleotide sequence, and NCBI blast showed that the 8 strains shared 99% homology with the GⅡ.17 variant strain 41 621 reported in Guangzhou. Conclusion The sauce elbow contaminated by norovirus was the main infection source of this outbreak of foodborne illness. It is suggested that we should strengthen the supervision and management of food production practices in catering industry for the prevention of recurrence of similar incidents.