To study the epidemiological characteristics of dengue fever(DF)cases and the molecular characteristics of local dengue virus(DENV)in Fujian from 2019 to 2022,and provide evidence for the prevention and control of DF.Statistically analyzed the demographic and epidemiological characteristics of imported and local DF cases.The locally prevalent strains from various regions and some imported strains were sequenced to analyze homology and construct phylogenetic trees by using software MEGA(version 6.0).A total of 1 661 DF cases,including 699 imported cases and 962 local cases were reported in Fujian from 2019 to 2022.The imported cases were mainly concentrated from June to October,whereas the local cases were mainly concentrated from August to October.All 10 cities in Fujian had imported cases reported,and local cases had been reported in all regions except Longyan.The male to female ratio in the imported cases(4.07∶1)was higher than that in the local cases(0.95∶1),and the median age of the imported cases(43 years old)was lower than that of the local cases(46 years old).The imported cases mainly came from Cambodia locally prevalent strains of DENV1 all belonged to genotypeⅠ,which may originate from other provinces or Southeast Asian countries such as Cambodia.The first locally prevalent cases of DENV4 were found in Putian,and the phylogenetic trees of DENV4 E gene showed that the locally prevalent strains of DENV4 in Putian were genotypeⅡ,which may originate from Singapore.They face a high risk of local DF outbreaks caused by imported DF cases,and the local epidemic areas appear a certain degree of spreading trend.It is necessary to strengthen the multi-sectoral cooperation and improve supervision systems.Timely discovery and tracing of cases to provide a basis for scientific prevention and control of DF.

To study the epidemiological characteristics of dengue fever(DF)cases and the molecular characteristics of local dengue virus(DENV)in Fujian from 2019 to 2022,and provide evidence for the prevention and control of DF.Statistically analyzed the demographic and epidemiological characteristics of imported and local DF cases.The locally prevalent strains from various regions and some imported strains were sequenced to analyze homology and construct phylogenetic trees by using software MEGA(version 6.0).A total of 1 661 DF cases,including 699 imported cases and 962 local cases were reported in Fujian from 2019 to 2022.The imported cases were mainly concentrated from June to October,whereas the local cases were mainly concentrated from August to October.All 10 cities in Fujian had imported cases reported,and local cases had been reported in all regions except Longyan.The male to female ratio in the imported cases(4.07∶1)was higher than that in the local cases(0.95∶1),and the median age of the imported cases(43 years old)was lower than that of the local cases(46 years old).The imported cases mainly came from Cambodia locally prevalent strains of DENV1 all belonged to genotypeⅠ,which may originate from other provinces or Southeast Asian countries such as Cambodia.The first locally prevalent cases of DENV4 were found in Putian,and the phylogenetic trees of DENV4 E gene showed that the locally prevalent strains of DENV4 in Putian were genotypeⅡ,which may originate from Singapore.They face a high risk of local DF outbreaks caused by imported DF cases,and the local epidemic areas appear a certain degree of spreading trend.It is necessary to strengthen the multi-sectoral cooperation and improve supervision systems.Timely discovery and tracing of cases to provide a basis for scientific prevention and control of DF.

Objective: The aim of this study was to update the epidemic situation of dengue fever (DF) and provide new insights for the consideration of disease control in Fujian province, China. Methods: Details about DF cases in Fujian reported during 2004-2017 were collected and analyzed. The envelope (E) genes of isolates of dengue virus (DENV) were sequenced for phylogenetic analysis. Results: The number of imported DF cases had increased dramatically since 2013, and the source regions expanded from Southeast Asia to South Asia, America, Oceania, and Africa, as well as the surrounding provinces. This resulted in local outbreaks and indigenous cases of DF that occurred more frequently, with 10 of 13 local outbreaks and 85.9% (1,252/1,458) of indigenous cases reported in 2013-2017. Compared with only two coastal cities before 2013, four coastal and one inland city in 2013-2017 experienced the local DF outbreaks. The phylogenetic analysis of E genes confirmed that the import of DENV, not only from abroad but also from the surrounding provinces, played an important role in dissemination and local outbreaks of DF in Fujian. Conclusions The frequent import of DF cases from not only abroad but also the surrounding provinces resulted in increased incidence, frequent local outbreaks, and expansion of distribution in Fujian in recent years. There is a need for urgent measures to improve disease control in this province.

The mosquito Aedes albopictus is the primary vector for dengue virus transmission in Fujian Province.Despite that active dengue surveillance has been launched in several sites since 2005,the genetic diversity of A.albopictus from these sites remains exclusive.In this study,mosquito pools collected from dengue surveillance sites during 2015-2016 were randomly selected,the full-length mitochondrial cytochrome C oxidase subunit Ⅰ (mtDNA-COⅠ) were amplified and sequenced.Preliminary sequence alignment of 12 amplicons with the reference sequence indicated 99 ％ homology at nucleotide level,due to varia tions at 9 nucleotide sites.Three haplotypes,namely H02,H03 and H08,were determined based on phylogenetic analysis with 72 reference sequences of known haplotypes.These observations facilitate surveillance and control of arboviral diseases in Fujian.