Epidemiological Characteristics and Risk Factors of Severe Fever With Thrombocytopenia Syndrome in Yantai City, Shandong Province

This study aimed to understand the epidemiological characteristics and risk factors for SFTS occurrence. The presence of rats in the household, bitten by the ticks one month before the onset of symptoms and presence of weeds and shrubs around the house were risk factors for SFTS. Background To better understand the epidemiological characteristics and risk factors associated with the incidence of severe fever with thrombocytopenia syndrome (SFTS) in Yantai City, Shandong Province, China. Methods The SFTS data from 2010 to 2019 were obtained from the National Notifiable Disease Reporting System, and visualization was performed using ArcGIS 10. A community-based, 1:2 matched case-control study was conducted to investigate the risk factors for SFTS in Yantai City. Standardized questionnaires were used to collect detailed information about the demographics and risk factors for SFTSV infection. Results A total of 968 laboratory-confirmed SFTS cases were reported, 155 (16.01%) of which were fatal. The SFTS epidemic curve revealed that most cases occurred from May to August, accounting for 77.27% of all studied cases. The SFTS cases were mainly distributed in Lai Zhou, Penglai, Zhaoyuan, Haiyang, and Qixia from 2010 to 2019 (accounting for 83.47% of all cases). No differences in demographics were observed between the cases and controls. In the multivariate analysis, presence of rats in the household (odds ratio [OR] = 2.89, 95% confidence interval [CI] = 1.94-4.30), bitten by the ticks 1 month before the onset of symptoms (OR = 15.97, 95% CI = 5.36-47.60), and presence of weeds and shrubs around the house (OR = 1.70, 95% CI = 1.12-2.60) were found to be the risk factors for SFTS. Conclusions Our results support the hypothesis that ticks are important vectors of the SFTS virus. Education on SFTS prevention and personal hygiene should be imparted in high-risk populations, especially among outdoor workers living in SFTS-endemic areas, while vector management should also be considered.