Combined effects of hydrological conditions and socioeconomic factors on the seasonal dynamics of severe fever with thrombocytopenia syndrome in China, 2011-2022: a modelling study

Hong-Han Ge; Kun Liu; Fang-Yu Ding; Peng Huang; Yan-Qun Sun; Ming Yue; Hong Su; Qian Wang; Nicholas Philip John Day; Richard James Maude; Dong Jiang; Li-Qun Fang; Wei Liu

doi:10.1016/j.lanwpc.2025.101564

Combined effects of hydrological conditions and socioeconomic factors on the seasonal dynamics of severe fever with thrombocytopenia syndrome in China, 2011-2022: a modelling study

Lancet Reg Health West Pac. 2025 Apr 28:58:101564. doi: 10.1016/j.lanwpc.2025.101564. eCollection 2025 May.

Authors

Hong-Han Ge^{1

2}, Kun Liu³, Fang-Yu Ding^{4

5}, Peng Huang⁶, Yan-Qun Sun⁷, Ming Yue⁸, Hong Su⁹, Qian Wang^{10

11}, Nicholas Philip John Day^{10

11}, Richard James Maude^{10

11}, Dong Jiang^{4

5}, Li-Qun Fang², Wei Liu^{2

9}

Affiliations

¹ School of Public Health, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China.
² State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Science, Beijing, China.
³ Department of Epidemiology, The Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, The Shaanxi Provincial Key Laboratory of Environmental Health Hazard Assessment and Protection, School of Public Health, The Fourth Military Medical University, Xi'an, China.
⁴ Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
⁵ College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
⁶ Department of Epidemiology, Center for Global Health, School of Public Health, National Vaccine Innovation Platform, Nanjing Medical University, Nanjing, China.
⁷ Clinical Research Center, Children's Hospital of Nanjing Medical University, Nanjing, China.
⁸ Department of Infectious Diseases, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
⁹ School of Public Health, Anhui Medical University, Hefei, China.
¹⁰ Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK.
¹¹ Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.

Abstract

Background: Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne viral hemorrhagic fever with expanding geographical range. The determinants of the seasonal dynamics of SFTS remain poorly understood.

Methods: Monthly SFTS cases from 604 counties in five provinces with high-notification rate in China (2011-2022) were analyzed using hierarchical Bayesian spatiotemporal and distributed lag nonlinear models. Cumulative and month-specific effects of meteorological factors were assessed, with socioeconomic factors as modifiers.

Findings: The cumulative effect peaked at 21.97 °C (RR = 1.24, 95% CI: 1.10-1.40) and the month-specific effect peaked at 25.67 °C (RR = 1.38, 95% CI: 1.26-1.51) without time lag. Increased precipitation significantly amplified the risk of SFTS with a notable lag effect observed. Both drought and wet conditions heightened the risk of SFTS occurrence substantially, with cumulative RR peaking at 3.13 (95% CI: 1.58-6.23) for Standardized Precipitation Evapotranspiration Index (SPEI-1) of -2.5, indicating drought conditions, and peaking at 1.51 (95% CI: 1.00-2.27) for SPEI-1 of 2.16, indicating wet conditions. The highest month-specific RR was observed at an SPEI-1 of -2.5 with a 2-month lag and at 1.81 with a 1-month lag, respectively. The risk of SFTS was higher in low-urbanization areas during drought, while was higher in high-urbanization areas with wet conditions.

Interpretation: Climatic factors significantly influence SFTS dynamics, with socioeconomic conditions modifying these effects. Integrating climate factors into surveillance and early warning systems is essential for targeted prevention and control.

Funding: National Natural Science Foundation of China (No. 82330103 and No. 42201497), Youth Innovation Promotion Association (No. 2023000117), and the Wellcome Trust [220211].

Keywords: Exposure-lag-response association; Extreme climate; Hydrological conditions; Severe fever with thrombocytopenia syndrome; Socioeconomic factors; Tick-borne disease.