4起城区登革热暴发疫情流行特征分析

Epidemiological characteristics of four Dengue outbreaks in Hangzhou urban areas

目的对杭州市4起城区登革热暴发疫情的流行病学及病原特征进行研究。方法采用描述性流行病学方法分析4起城区暴发疫情流行病学特征。应用RT-PCR方法检测血清标本中的登革病毒核酸及其型别,挑选11株代表性病毒株进行病毒分离、E基因扩增、序列测定及构建进化树。结果4起城区登革热暴发疫情共报告26例本地病例,发生时间集中在2019年7月下旬—10月上旬,60%的病例年龄在40岁及以上,职业分布以职员最多,其次为退休人员和工人。分离到登革病毒株24株,分型均为登革病毒Ⅰ型。选取11株代表性病毒E基因序列比对及进化分析,分离病毒株与菲律宾、越南病毒株核苷酸序列一致性最高。结论4起城区暴发疫情由登革病毒Ⅰ型引起,传染源可能来自菲律宾和越南。

Objective To analyze the epidemiological and etiological characteristics of four Dengue fever outbreaks in Hangzhou City.Methods Descriptive epidemiological method was used to analyze the epidemiological characteristics.Serum samples were collected from Dengue fever cases for virus detecting and serotyping by reverse transcription-polymerase chain reaction(RT-PCR).Eleven representative virus strains were selected for virus isolation,envelope(E)gene amplification,sequence determination and phylogenetic tree construction.Results A total of 26 local Dengue cases were reported in the four urban outbreaks,which occurred from late July to early October in 2019.60%of the cases were aged 40 years and above,and the occupational distribution was most common among employees,followed by retirees and workers.Twenty-four Dengue virus strains were isolated,all of which were classified as Dengue virus typeⅠ.11 representative virus strains were selected for E gene sequence alignment and evolutionary analysis,and the nucleotide sequence consistency of the isolated virus strains with the Philippines and Vietnam virus strains was the highest.Conclusion The outbreaks occurred in 2019 caused by Dengue virus typeⅠ.The source of infection might be caused by imported Dengue fever cases from Philippines and Vietnam.