北京市首例Ⅰ型疫苗高变异脊髓灰质炎病毒病例的流行病学调查与分析

Epidemiological Investigation of the First Case Caused by Type I Vaccine Highly-mutant Poliovirus in Beijing

目的对北京市首例Ⅰ型(Type1)疫苗高变异脊髓灰质炎(脊灰)病毒[Vaccine High-mutant Poliovirus(PV),VHMPV_Ⅰ]病例进行流行病学调查分析。方法开展VHMPV病例个案调查、排毒监测、病毒传播风险评估、消毒隔离。结果患儿为北京市户籍,患有肛门周围脓肿,有1剂口服脊灰减毒活疫苗(Oral Poliomyelitis Attenuated Live Vaccine,OPV)接种史,麻痹前随母亲到河北省大厂回族自治县暂住,发病后采集3份合格粪便标本,经中国疾病预防控制中心病毒病预防控制所国家脊灰实验室核苷酸序列测定为VHMPV_Ⅰ病例。间隔14天采集患儿粪便标本4份,密切接触者采集单份粪便标本7份,PV分离和逆转录-聚合酶链反应检测均为阴性;病例居住地所在乡OPV接种率调查、相邻乡和流动人口聚居乡OPV接种率快速评估均未发现OPV零剂次免疫儿童;医院和社区急性弛缓性麻痹性病例主动搜索未发现漏报病例;病例采取消化道隔离方式直至疫情结束。结论 VHMPV_Ⅰ病例可能为低免疫水平儿童,由外环境感染导致发病;应进一步开展VHMPV_Ⅰ基因突变与神经毒力关系研究。

Objective To investigate the first case of a type I Vaccine Highly-mutant Poliovirus （VHMPVI） in Beijing. MethodS We conducted an epidemiological investigation with virus excretion monitoring, risk assessment, disinfection, and isolation . Results The case, a Beijing resident with a perianal ab- scess, received one dose of oral polio vaccine （OPV） , and had stayed in Hebei with his mother before paralysis onset. Three qualified stool samples were collected, from which a VHMPVI was isolated by the National Polio Laboratory（NPL）. A total of 4 stool samples, with two qualified stool samples every 14 days, were collected from the case. Seven stool samples were collected among close contacts. All samples were negative by PV isolation and RT-PCR （Reverse Transcription Polymerase Chain Reaction ）. We conducted an OPV coverage assessment in the residential township of the case, and a rapid coverage as- sessment in nearby townships and a township with clusters of the floating population. There were no chil- dren with zero doses of OPV. There were no missed AFP case from the community and hospitals. The case was isolated with gastrointestinal precautions until proven noninfectious. Conclusion This may have been a case that was infected from an external environmental source. Further research on the relationship between genetic variation of VHMPV and neuro-virulence should be conducted.