2019年北京市大兴区诺如病毒GI引起急性胃肠炎疫情的病原学分析

Etiological analysis of acute gastroenteritis caused by norovirus GⅠin Daxing District of Beijing in 2018

目的对2019年6月北京市大兴区一所幼儿园和两所小学急性胃肠炎疫情进行诺如病毒病原学分析。方法采集发生疫情的幼儿园和小学病例粪便标本共19份,采用实时荧光RT-PCR检测方法,进行诺如病毒GⅠ/GⅡ型核酸检测,对阳性标本采用一步法RT-PCR扩增诺如病毒衣壳蛋白区(VP1)基因,对其产物进行测序,用BioEdit7.0.9.0软件进行序列比对,用MEGA 6.06软件构建进化树。结果19份标本中,诺如病毒GⅠ总检出率为89.5%(17/19)。测序和进化分析,10株为GI.6b,1株为GI.2。疫情株GI.6b和GI.2不仅与其他地域人源参考株高度同源(相似性为99.6%~95.3%),也与其他地域污水中检出的参考株高度同源(相似性为100.0%~98.9%)。结论幼儿园疫情由诺如病毒GI.6b感染引起,两所小学疫情分别由诺如病毒GI.2和GI.6b感染引起。应加强诺如病毒少见毒株GI.6b和GI.2日常监测,提高防控能力。

Objective Etiological analysis of acute gastroenteritis in a kindergarten and two primary schools was conducted in Daxing District of Beijing in June 2019.Methods A total of 19 stool samples were collected from kindergartens and primary schools with acute gastroenteritis.The real-time fluorescent RT-PCR was used to detect the nucleic acid of the virus in the fecal samples collected from the outbreaks.The positive samples were amplified by one-step RT-PCR to amplify some genes of Norovirus capsid protein region(VP1).And the positive product was sequenced.Bioedit7.0.9.0 software was used for sequence alignment,and the phylogenetic tree was constructed by MEGA 6.06 software.Results The total detection rate of norovirus GⅠwas 89.5%(17/19).10 virus strains were GⅠ.6b and 1 virus strain was GI.2 by sequencing and evolutionary analysis.The epidemic strains GⅠ.6b and GI.2 were not only highly homologous(similarity 99.6%-95.3%),with the reference strains from other regions,but also highly homologous(similarity 100.0%-98.9%)with the reference strains from other regions.Conclusion The kindergarten outbreak was caused by norovirus GI.6b,while the outbreaks in two primary schools were caused by Norovirus GI.2 and GI.6b respectively.Routine surveillance of norovirus strains GI.6b and GI.2 should be strengthened to improve the ability of prevention and control.