| Objective:In this study,the SFTS case data from January 2011 to December 2017 in Liaoning Province were collated and analyzed.According to the stratified random sampling,five SFTSV isolates were randomly selected for whole genome nucleotide sequence determination.The epidemiology of SFTS in Liaoning Province and the variation of genotypes of isolated samples in each year were obtained.To detect the role of long-horned blood stasis in the process of disease transmission by detecting STFSV nucleic acid in long-horned blood stasis.Provide theoretical support and reference for SFTS prevention and control work.Methods:1.Organize the SFTS case information in Liaoning Province from January2011 to December 2017,and analyze the epidemiological characteristics of SFTS by descriptive analysis.2.Geographical distribution map of the residence of SFTS patients in Liaoning Province was drawn by Arc Gis10.5 software.3.Collect sputum specimens in the SFTS epidemic area of Liaoning Province,use the artificial cloth flag method for free sputum,and use the sputum method for parasitic cockroaches.The sputum specimen was ground,and the nucleic acid was extracted and detected by Real-time PCR.4.Real-time PCR was used to detect serum samples from SFTS patients in different cities of Liaoning Province,and positive samples were isolated and cultured.Positive samples of virus isolation and culture were randomly sampled by year,and 5 strains were randomly selected each year.5.Nucleotide amplification and sequencing of the entire gene sequences(S,M and L fragments)of the selected isolates using specific primers.Phylogenetic tree and homology analysis of Mega 6.0 software.Results:1.From January 2011 to December 2017,a total of 438 confirmed cases of SFTS were reported in Liaoning Province,and 19 deaths were reported.The case fatality rate was 4.33%.The affected population is mainly middle-aged and elderly people over 50 years old,accounting for 89.95% of the total reported cases.Farmers are high-risk groups of SFTS,accounting for 61.64% of the total reported cases.2.The SFTS epidemic situation in Liaoning Province began to rise from the end of March or early April,and the peak of the epidemic in July-September.The peak of the epidemic in each year gradually decreased after September,and there were basically no cases reported from November to February.3.The incidence of SFTS has obvious geographical distribution characteristics.The high incidence areas in Liaoning Province are Dandong City and Dalian City.4.The dominant species in the epidemic area of ??Liaoning Province is long-horned blood stasis.SFTSV nucleic acid test-the positive rate of parasitic sputum was 26%,and the positive rate of free sputum was 4%.5.SFTSV isolated samples from Liaoning Province were identified and compared by pathogen sequence.In 2011-2017,SFTSV in Liaoning Province passed the prevalent dominant strains as C2 and C3 subtypes.The isolated samples from Liaoning Province have high nucleotide homology with each other,and the nucleotide homology of the three fragments(S,M and L)is 94.4%-100%,92.20%-100% and 90.20%-100%.Conclusions:1.The population of SFTS in Liaoning Province from 2011 to 2017 is mainly middle-aged and elderly farmers,among which middle-aged and elderly farmers aged ≥50 years old.2.The peak incidence of SFTS in Liaoning Province is from July to September,and the incidence of SFTS has obvious seasonality.3.The high incidence area of SFTS epidemic in Liaoning Province is Dandong City and Dalian City,and the disease has obvious geographical distribution characteristics.4.The dominant species in the epidemic area of Liaoning Province is long-horned blood stasis,and SFTSV is detected in both parasitic and free mites.5.SFTS pathogen sequence determination and comparison in Liaoning Province found that the SFTSV isolates in Liaoning Province were mainly C2 and C3 subtypes,which is consistent with domestic reports.6.The results of this study provide a theoretical basis for the diagnosis and prevention of SFTS. |
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