Epidemiology and genotyping of dengue fever in Shenzhen City in 2018 / 中华传染病杂志

ABSTRACT

Objective:To investigate the epidemiological characteristics of dengue fever and genotyping of the epidemic strains of dengue virus in Shenzhen City in 2018.Methods:Descriptive epidemiological analysis was used to analyze dengue fever prevalence in Shenzhen City in 2018. Blood samples of patients with dengue fever were collected. The colloidal gold immunochromatography was used to detect serum specific IgM and IgG antibodies, and real-time fluorescence quantitative polymerase chain reaction (PCR) was used to detect viral nucleic acids and to identify genotypes. The E gene sequence of isolated virus strain was amplified by reverse transcription PCR. Homology comparison and phylogenetic tree of dengue fever epidemic strains in different countries and regions were conducted. Results:A total of 234 cases of dengue fever were reported in Shenzhen City from January 1 to December 31, 2018. The incidence rate was 1.87/100 000. There were 144 (61.54%) local patients and 90 (38.46%) imported patients, who were mainly from Southeast Asia and surrounding cities. Two hundred and two (86.32%) cases were reported during the epidemic peak period from August to November of the year. The patients mainly aged 20 to 50 years old (195 cases, 83.33%). Dengue virus type (DENV)-1 accounted for 86.01%(166/193), DENV-2 accounted for 10.36%(20/193), DENV-3 accounted for 2.59%(5/193), and DENV-4 accounted for 1.04%(2/193). The local cases were all infected with DENV-1. The homologies of nucleotide sequence and the deduced amino acid sequence of E gene of 24 DENV-1 strains with HAWAII45 strain were 93.0% to 94.6% and 96.6% to 97.2%, respectively. The phylogenetic tree of DENV-1 strains revealed that 23 strains belonged to genotypeⅠ, and one strain belonged to genotype Ⅳ which was the first reported imported cases in Shenzhen City. The homologies of nucleotide sequence and the deduced amino acid sequence of E gene of six DENV-2 strains with NGC strain were 93.1%to 93.9% and 97.0% to 97.8%, respectively. The phylogenetic tree of DENV-2 strains showed that two strains belonged to genotype Cosmopolitan and four strains belonged to genotype Asian Ⅰ, which were first reported in Shenzhen City. Conclusions:The epidemic of dengue fever in Shenzhen City in 2018 has the characteristics of coexistence of local and imported transmission. The main epidemic genotype is DENV-1. It infers that the major virus strains may be imported from Southeast Asia countries and surrounding cities. Therefore, attention should be paid to the epidemic trend of local dengue fever.