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目的:分析汕头市2018年和2019年登革病毒主要流行毒株的分子特征，探讨两年间该市登革热呈现截然不同的流行态势的内在原因，同时了解病毒的传播特点和途径，为登革热疫情的防控提供决策依据。方法:对2018年和2019年检测到的共872例核酸阳性样本进行病毒核酸含量判定、n E基因扩增和序列测定，并构建系统进化树，从树结构上分析毒株的同源性特点，并推测可能的来源和传播途径。n 结果:共获得登革毒株的n E基因序列99条，其中1型序列68条，2型序列31条；2018年的登革热呈现散发态势，系统进化树显示对应的毒株呈现多源性特点，与发现于广州及东南亚地区的毒株密切相关；2019年的登革热呈现暴发态势，对应的流行毒株主要为单一来源特点，毒株来源推测为柬埔寨。n 结论:汕头市登革热的本地流行主要为当年的输入性毒株引起的，未见往年本地毒株引起的流行；东南亚地区或为汕头市流行的登革毒株主要发源地，并可通过多种路线传入汕头市。“,”Objective:To analyze the molecular characteristics of dengue virus (DENV) strains circulating in Shantou city in 2018 and 2019 for elucidating the reasons causing strikingly different dengue fever epidemics during the two years and understanding the transmission characteristics and routes of DENV, and to provide reference for the prevention and control of dengue fever.Methods:Detection of viral nucleic acid contents and amplification and sequencing of n E gene were carried out on 872 samples positive for DENV acid in 2018 and 2019. Phylogenetic trees were constructed based on the n E gene sequences to analyze the homology of DENV strains. The sources and transmission routes of the strains were also analyzed.n Results:A total of 99 sequences of DENV n E gene were acquired, including 68 DENV-1 sequences and 31 DENV-2 sequences. The cases of dengue fever were sporadic in 2018. Phylogenetic tree showed the strains isolated in 2018 were from multi-sources and closely related to those found in Guangzhou city and Southeast Asia area. Dengue fever outbreaks occurred in 2019 and most of the prevalent strains were from a single source, which was speculated to be Cambodia.n Conclusions:Dengue fever in Shantou city was mainly caused by imported strains of the same year rather than by local strains in previous years. DENV strains in Shantou might be traced back to Southeast Asia area and transmitted to Shantou through many routes.