云南省瑞丽市2013年登革热暴发的分子流行病学研究

Molecular epidemiologic analysis of an outbreak of dengue fever in 2013 at Ruili city,Yunnan province of China

目的调查云南省德宏州瑞丽市2013年登革热（denguefever,DF）暴发疫情的情况,掌握其分子流行病学特点。方法收集登革热病例资料,采集急性期患者血清标本,用RT-PCR法检测登革病毒（dengue virus,DENV）核酸,并进行登革病毒C/PreM区核苷酸序列测定和分析。结果 2013年8~11月,瑞丽市共确诊登革热232例,其中本地感染病例145例（62.50%）,缅甸输入性病例87例（37.50%）。2013年瑞丽市登革热本地感染病例发病率为77.69/10万。主要流行地区为瑞丽市城区（53.45%,124/232）、姐告镇（16.81%,39/232）和勐卯镇（8.19%,19/232）。经序列测定,获得17株病毒的C/PreM区基因核苷酸序列,系统进化分析表明,5株为登革Ⅰ型病毒,12株为登革Ⅱ型病毒,均与东南亚登革病毒流行株具有较近的亲缘关系。结论瑞丽市在2013年发生了输入性和本地感染并存的登革热流行,并存在登革Ⅰ型和Ⅱ型病毒共同流行,来自缅甸的登革热输入性病例是引起本次登革热本地流行的主要原因。加强输入性病例的监测和管理是防止该病再次流行的关键措施。

Objective To understand the molecular epidemiologic features of an outbreak of dengue fever happened in 2013 in Ruili city,Yunnan province of China.Methods Serum samples from acute stage of dengue fever patients were collected to detect the viral nucleic acid by RT-PCR.The phylogenetic tree was analyzed and generated based on the nucleotide sequence of C/PreM gene fragments of the dengue virus.Results A total of 232 cases of dengue fever were confirmed basing on laboratory diagnosis in Ruili city from August to November,2013.All patients,145（62.50%）were local infections by mosquitoes bites and the incidence rate was 77.69/100,000 in this city,while 87cases（37.50%）were imported from Myanmar to Ruili city of Yunnan,China.Major epidemics was in urban areas（124cases,53.45%）of Ruili as well as Jiegao town（39cases,16.81%）and Mengmao town（19cases,8.19%）of the city.Virus strains isolated from serum samples of dengue fever cases were partially sequenced and phylogenetic analysis was performed according to the nucleotide sequence of the C/PreM gene fragments.Five isolates were categorized as dengue type I and 12 as dengue typeⅡ.All 17 strains share high homology with that from Southeast Asia countries.Conclusions During the outbreak of dengue fever in 2013 at Ruili city,Yuannan province of China,both local and imported cased were identified.Imported cases from Myanmar was the main source for the local epidemic.