Epidemiology and Demographic Trends of Severe Fever With Thrombocytopenia Syndrome in Shandong Province From 2015 to 2022: A Comprehensive Analysis

Abstract

The study aimed to provide a comprehensive description of the prevalence and distribution of severe fever with thrombocytopenia syndrome (SFTS) cases in Shandong province, the region most severely affected by the SFTS epidemic globally, from multiple perspectives. From 2015 to 2022, Shandong province reported 5624 cases of SFTS, with a confirmation rate rising from 71.29% to 91.87% and an incidence rate increasing from 0.51 to 0.99 per 100 000. The case fatality rate (CFR) fluctuated, peaking at 12.34% in 2019 and dipping to 7.14% in 2016. Most cases were concentrated in the central region and Jiaodong Peninsula, with Yantai, Weihai, and Jinan accounting for 67.89% of total cases. SFTS incidence peaked from April to October, with cases rising from 498 in 2015 to 1009 in 2022, transitioning from a bimodal to a unimodal distribution. Male mortality averaged 10.32% and female mortality averaged 7.81%, significantly increasing with age, especially in the 70–79 (13.30%) and over-80 (13.76%) groups. Notably, the proportion of cases in the 70–79 age group has been increasing year by year. The absolute increase in cases among farmers was the largest, while the highest growth rate was observed in household/unemployed individuals. These findings highlight the need to reevaluate our strategies for addressing previously identified high-risk populations.