Epidemiological characteristics of scarlet fever and genomic genetic evolution of Group A Streptococcus in Xinjiang from 2013 to 2022
Objective To analyze the incidence and epidemic trend of scarlet fever and the genomic characteristics of Group A Streptococcus(GAS)in Xinjiang from 2013 to 2022,and provide evidence for accurate source tracing of scarlet fever epidemic.Methods Descriptive epidemiological method was used to analyze the data of scarlet fever cases from Xinjiang infectious disease surveillance system during 2013 to 2022.The throat swab samples were collected from sentinel hospitals during 2021 to 2023 for strain isolation and identification,drug sensitivity test,PFGE typing and whole genome sequencing.The phylogenetic tree was constructed by FastTree as the whole genome-based single-nucleotide polymorphisms(wgSNP)sequence.Results A total of 20 954 cases with scarlet fever were reported in Xinjiang from 2013 to 2022,with an average annual incidence of 8.66/100 000.The incidences showed two peaks.Karamay,Hami and Urumqi were the top three regions ranked as incidence,and the annual reported incidence was 55.05/100 000,22.55/100 000 and 21.55/100 000,respectively.The cases of children aged 1-10 years accounted for 97.04%.29 strains of GAS were sensitive to 12 antibiotics such as penicillin,moxifloxacin and cefotaxime et al.,and resistant to erythromycin,tetracycline and clindamycin.The emml2 and ST36 were the dominant strains of Xinjiang GAS,and spy005 and spy006 were the dominant strains of PFGE.There were 13 drug resistance genes and 38 virulence genes detected in 28 strains.Phylogenetic analysis based on wgSNP was carried out in all 103 GAS strains in China and neighboring countries include local 28 GAS strains.The results showed the strains divided into 7 branches,and the genetic relationships existed in them.Conclusions The incidence of scarlet fever increased in Xinjiang from 2013 to 2018,and decreased since 2019.The main endemic strains of Xinjiang GAS are emml2 and ST36,which closely relate to the domestic endemic strains.No new emm genotype is found.
Scarlet feverEpidemic characteristicsGroup A StreptococcusGenome evolution