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目的了解2015年11月浙江省温州市洞头区鹿西乡疑似病毒性脑炎暴发疫情的病原及基因特征,分析其基因变异情况并进行病原溯源。方法开展流行病学调查,采集32例患者和75例密切接触者的咽拭子和粪便样本共140份,检测人类肠道病毒(HEV)核酸和分离病毒,对HEV分离株VP1基因测序,进行同源性与进化分析。结果疫情波及鹿西乡小学和幼儿园共计396名学生,其中发病32例,罹患率8.1%(32/396)。临床症状为发热、头痛、呕吐等。从32例患者和75例密切接触者样本中,分别检测到30例和5例HEV核酸阳性,阳性率分别为93.8%和6.7%,共分离到23株肠道埃可病毒30型(ECHO30)。ECHO30分离株之间VP1区核苷酸和氨基酸同源性分别为99.9%~100.0%和99.7%~100.0%,新分离株与ECHO30原型株之间VP1区核苷酸和氨基酸同源性分别为81.8%和92.1%。系统进化分析显示新分离株位于ECHO30进化支Ⅰ的基因亚型分支上,与2013年浙江省CHN/ZJ/RA-72/2013株,2014年ZJ/JH Chen/2014株亲缘关系最近。结论引起2015年11月浙江省温州市洞头区鹿西小学及幼儿园聚集性病毒性脑炎暴发疫情的病原为ECHO30 GⅠ进化支病毒。
Objective To understand the etiopathogenisis and genetic characteristics of suspected outbreaks of viral encephalitis in Lu Xixiang, Dongtou District, Wenzhou City, Zhejiang Province in November 2015. To analyze the genetic variation and pathogen tracing. Methods A total of 140 throat swabs and stool samples from 32 patients and 75 close contacts were collected for epidemiological investigation. The human enterovirus (HEV) nucleic acids were isolated and the virus was isolated. The VP1 gene of HEV isolates were sequenced Homology and evolutionary analysis. Results The epidemic affected a total of 396 students in Lu Xixiang Primary School and kindergarten, of which 32 cases were affected, with an attack rate of 8.1% (32/396). Clinical symptoms of fever, headache, vomiting and so on. Thirty cases and five cases of HEV nucleic acid were detected respectively in 32 samples and 75 cases of close contacts, the positive rates were 93.8% and 6.7%, respectively. Twenty-three strains of ECHO30 were isolated, . The nucleotide and amino acid homology of VP1 in ECHO30 isolates were 99.9% -100.0% and 99.7% -100.0%, respectively. The homology of nucleotide and amino acid in VP1 of new isolate and ECHO30 were 81.8% and 92.1%. Phylogenetic analysis showed that the new isolate was located on the branch of gene subdivision of clade I of ECHO30, which was the closest to the 2013 CHN / ZJ / RA-72/2013 strain in Zhejiang Province and 2014 ZJ / JH Chen / 2014 strain. Conclusion The ECHO30 GⅠ clade virus, which caused the outbreak of the cluster outbreak of viral encephalitis in Luxi Primary School and kindergarten in Dongtou District, Wenzhou City, Zhejiang Province in November 2015, was identified.