Abstract
Objective To investigate the epidemiological characteristics of dengue fever in Shenzhen city in 2014 and to analyze the evolutional characteristics of the epidemic dengue virus (DENV) strains in order to provide scientific guidelines for the prevention and control of dengue fever. Methods Descriptive epidemiological analysis was used to analyze the prevalence of dengue fever in Shenzhen city in 2014. Immunochromatography and real-time PCR were performed to detect the specific antibodies (IgM and IgG) and DENV nucleic acids in serum samples collected from suspected cases of dengue fever. Serum samples collected from the patients at early stage of dengue fever were used to infect the C6/36 cell line for further isolation of DENV strains. The types of isolated DENV strains were determined by using real-time PCR. E genes of the isolated DENV strains were amplified by RT-PCR and then sequenced. DNAStar and Clustslx (1.83) softwares were used to analyze the homology between DENV strains isolated in Shenzhen and other areas. A phylogenetic tree based on the sequences of E genes of Shenzhen strains and other sequences of DENV reference strains downloaded from GenBank was constructed for further analysis. Results A total of 454 cases of dengue fever were reported in Shenzhen in 2014 with a male to female ratio of 1.43∶1. Local patients accounted for 76.21% and the rest 23.79% were imported cases mainly from Southeast Asian and surrounding cities. There were 441 cases reported from September to November, accounting for 97.14% of all reported cases. Most of the infected subjects were aged 20 to 50, accounting for 76.73%. Of the 270 samples positive for DENV nucleic acids, strains of DENV-1, DENV-2, DENV-3 and DENV-4 accounted for 87.41%, 8.89%, 0.37% and 2.22%, respectively. The phylogenetic tree analysis revealed that the DENV-1 strains belonged to two genotypes, which were genotypeⅠ and genotype Ⅴ. The DENV strains of genotypeⅠ were highly similar to the epidemic strain isolated in Shenzhen in 2010 and the genotype Ⅴ strains were first reported in Shenzhen. The homology analysis of the nucleotides of E genes showed that minor differences in the nucleotide sequences were found between DENV-2 strains. All of the DENV-2 strains belonged to the genotype Ⅳ as indicated by the phylogenic tree. Conclusion There were 454 cases of dengue fever (including both local and imported cases) reported in Shenzhen city in 2014, reaching an all-time high. DENV-1 was the predominant pathogen in combination with an increased infection of DENV-2. This study indicated that the prevalent DENV strains might be imported from Southeast countries and neighboring cities. Further researches should be conducted to analyze whether dengue fever is endemic in Shenzhen City. Key words: Dengue virus; Epidemiological characteristics; E gene; Evolutional analysis
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
