陕西省手足口病重症和死亡病例的流行特征及肠道病毒71型VP1区基因特征分析

Epidemiology analysis on severe and dead cases of hand,foot and mouth disease,and genetic characteristics of the VP1 region of enterovirus A71 in Shaanxi Province,China

目的了解陕西省手足口病(HFMD)重症和死亡病例的流行特征及肠道病毒71型(EV-A71)基因特征,为制定防控措施提供参考依据。方法对2010-2015年陕西省HFMD监测数据和病原学资料进行分析,选择重症和死亡病例的EV-A71分离株用RT-PCR方法扩增VP1基因片段,MEGA5.0软件分析同源性并构建系统进化树。结果 2010-2015年陕西省共报告HFMD重症病例5 054例,死亡病例118例,年均报告死亡率0.052 09/10万,重症病死率2.32%。5-7月为重症和死亡病例发病高峰,西安、渭南、咸阳为高发地区。病例集中于3岁以下儿童,分别占重症和死亡病例总数的90.84%和93.22%,男性高于女性,男女性别比1.67∶1。病原学监测重症病例中EV-A71、CV-A16和其他肠道病毒的构成比分别为66.39%、6.26%和27.35%,不同年份的各病原构成有统计学差异(χ~2=307.827,P<0.001)。不同年龄组的EV-A71检出率最高,且随着年龄的增加不断增高,差异有统计学意义(χ~2=50.688 18,P<0.001)。死亡病例中EV-A71检出率达96.83%。29株EV-A71分离株的核苷酸和氨基酸同源性分别为94.2%～99.7%和98.0%～100%,与我国C4亚型代表株之间具有高度同源性,属于EV-A71病毒的C4基因亚型C4a进化分支。结论应做好重点地区、高发季节和≤3岁儿童的HFMD防控工作,密切关注EV-A71病原流行变化趋势,采取有效措施降低重症和死亡病例的发生。

We aimed to understand the epidemiological characteristics and genetic characteristics of human enterovirus71（EV-A71）pathogen of severe and dead cases of hand,foot and mouth disease（HFMD）in Shaanxi Province,and to provide scientific evidence for the prevention and control of the disease.The case-data of HFMD in Shaanxi Province from the Chinese National Notifiable Infectious Disease Reporting System were analyzed.VP1 genes of EV71 strains isolated from HFMD severe and dead cases were amplified by RT-PCR.The homology comparison and phylogenetic trees were performed with MEGA5.0 software.A total of 5 054 HFMD severe cases and 118 dead cases were reported in Shaanxi Province from 2010 to 2015,the average annual mortality rate was 0.052 09/100 000 and the fatality rate was 2.32%.The incidence peak occurred during May-July,the highest incidence was found in the regions of Xi’an,Weinan and Xianyang of the province.The 90.84%severe cases and 93.22% dead cases were under the age of three,the male-to-female ratio was 1.67∶1.Pathogen surveillance indicated that the proportion of EV-A71,CV-A16 and other enteroviruses were 66.39%,6.26%and 27.35%respectively.There were significant statistical differences of the type of pathogen in the different years.EV-A71 was the main pathogen in different age groups,the detection rate of EV-A71 increased with age.The dead cases were mainly caused by EV-A71 pathogen.A total of 29 strains of EV-A71 isolated from HFMD severe and dead cases were sequenced,the homology of nucleotides and amino acids among 29 strains were 94.2%～99.7% and 98.0%～100%,respectively.It was the highest homology with genotype C4 strains and all of isolated strains were belong to the C4 asub-genotype of EVA71.We should strengthen the surveillance in the prevalence season and carry out prevention and control in the important regions and children≤3 years old,pay attention to the epidemic trend of EV-A71 and take effective measures to reduce the incidence of severe and dead cases.