Objective: To study the epidemiology and the etiology characteristics of first imported severe fever with thrombocytopenia syndrome (SFTS) case reported in Shenzhen city in 2017. Methods: Data on descriptive epidemiology was collected to study the characteristics to the epidemic. The serum sample collected from the suspect SFTS case was detected for IgM, IgG by ELISA and severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) nucleic acid by real-time RT-PCR. The samples were further inoculated in Vero cell for virus isolation. The partial fragements of L and S gene were amplified by RT-PCR and sequenced to construct homology comparison and phylogenetic tree with the strains isolated from other areas. Results: The case was laboratory confirmed imported SFTS case in Shenzhen on May 2017. IgM antibody and RNA of SFTSV were detected in the serum sample. SFTSV named GDSZ01/2017/China was successfully isolated from the serum sample. The high nucleotide homology of L and S genome segments were found at 95.3%-98.2% and 93.8%-98.8% with other representative strains from the popular provinces, respectively. The phylogenetic tree indicated that GDSZ01 was most close to SDTA_3 strain, next to strains in Hubei procince. The isolated SFTSV belonged to genotype C3 with HB29, HB154. Conclusions The virological, serological and molecular features showed that the imported case of SFTS in 2017 was caused by SFTSV C3 genotype.

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.