甘肃省2008-2012年手足口病流行特征及病原学研究

Epidemiological Features and Pathogenic Characteristics of Hand,Foot and Mouth Disease in Gansu Province,China during 2008-2012

分析甘肃省手足口病流行特征及病原学特征，为制定有效的防控策略提供依据。采用描述性流行病学分析方法对甘肃省手足口病发病资料进行分析，采集的病例临床标本用RT—PCR或Real-time PCR法检测肠道病毒（Human enterovirus，HEV）核酸，用RD和HEp-2细胞分离病毒，阳性病毒株采用RT—PCR方法扩增全长VP1编码区后，进行核苷酸序列测定和分析。结果表明2008-2012年共报告手足口病病例52550例，包括重症病例205例，死亡病例27例。5年全省发病率依次为22．42／10万、49．29／10万、47．20／10万、27．27／10万和55．84／10万，全省14个市州均有发病。兰州市发病数最高为16001例，占全省病例的30．45％，发病集中在5～7月，占全年病例的51．69％，男女性别比为1．69；1，其中5岁以下儿童发病占87．59％。对5416例病例标本进行了实验室检测，HEV核酸阳性3322例（阳性率61．34％），其中肠道病毒A组71型（Enterovirus A71，EV71）占46．96％，柯萨奇病毒A组16型（coxsackievirus A16，CVA16）占41．57％，其他HEV占11．47％。对186例重症病例进行实验室检测，HEV核酸阳性114例（阳性率61．29％），其中EV71占82．46％；对25例死亡病例进行实验室检测，均为EV71感染。从3111份临床标本（咽拭子2123份，粪便705份，疱疹液705份）分离到病毒402株，其中EV71占70．15％，CVA16占27．11％，其它柯萨奇A组病毒占3．98％，柯萨奇B组病毒占2．49％，埃可病毒占1．74％，腺病毒占1．99%。流行HEV的基因型分析结果显示，2008～2012年分离到的194株EV71均为C4基因亚型的C4a进化分支；45株CVA16均为B1基因亚型，其中12株属于Bla进化分支，33株属于Blb进化分支，2012年Blb已成优势亚型。结论是甘肃省手足口病在5岁以下儿童感染率最高，主要病原为EV71和CVA16，发病率随感染病原型别的不同呈现波浪形变化，不同病原呈现交替流行的现象，重症和病死病例与EV71感染密切相关，同一年度不同地区的病原型别存在差异。

Abstract：This study aims to analyze the epidemiological features and pathogenic characteristics of hand, foot and mouth disease （HFMD） in Gansu Province, China and to provide a basis for the development of effective prevention and control measures. The descriptive epidemiological analysis was used to analyse the data of HFMD cases in Gansu. The specimens collected from hospitals were subjected to RT-PCR or realtime PCR to detect human enterovirus （HEV） nucleic acid, and HEV strains were isolated using human rhabdomyosarcoma cells and human laryngeal carcinoma cells. The complete VPl-encoding region of several identified enterovirus A71 （EV71） and coxsackievirus A16 （CVA16） was subjected to full-length amplification by RT-PCR and then to sequencing and analysis. A total of 52 550 HFMD cases were reported in Gansu from 2008 to 2012, including 205 severe cases and 27 deaths. The incidence rates in the whole province from 2008 to 2012 were 22.42/10^5 , 49.29/10^5 , 47.20/10^5 , 27.27/10^5 , and 55.84/10^5, respectively. There were cases in all the 14 cities or prefectures in Gansu, and Lanzhou had the largest number of cases （16 001 cases）, accounting for 30.45% of all cases in the province. HFMD cases were mostly reported during May to July, accounting for 51.69% of all cases throughout the year. The male-to-female ratio was 1.69：1. Of all the cases, 87.59% were under the age of five. Of the 5 416 cases for laboratory tests, 3 322 （61.34%） were positive for HEV nucleic acid, including EV71 （46.96%）, CVA16 （41.57%）, and other HEVs （11.47%）. Among the 186 severe cases, 114 （61.29%） were positive for HEV nucleic acid, and 82.46% of the positive cases for EV71. All the 25 dead cases were infected with EV71. A total of 402 strains were isolated from 3 111 specimens collected from hospitals （2 123 throat swab specimens, 705 stool specimens, and 705 herpes specimens）, including EV71 （70.15%）, CVA16 （27.11）, other coxsackievirus A （3.98%）, coxsackievirus B （2.49%）, echovirus （1.74%）, and adenovirus （1.99%）. The genotyping of VP1- encoding region showed that all the 194 EV71 strains isolated during 2008-2012 belonged to the C4a evolutionary branch of C4 subtype; among the 45 CVA16 strains, 12 belonged to the Bla evolutionary branch of B1 subtype and 33 to the Bib evolutionary branch, and Blb became the predominant subtype in 2012. In conclusion, in Gansu Province, HFMD occurs mostly in children under the age of five; EVT1 and CVA16 are the main pathogens of this disease, and the two are predominant alternately from 2008 to 2012; the severe and dead cases of HFMD are closely related to infection with EV71; the types of pathogens varied across different regions in the same year during 2008-2012.