State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 20 Dong-Da Street, Fengtai District, Beijing, 100071, People's Republic of China.
Department of Laboratorial Science and Technology, School of Public Health, Peking University, Beijing, 100191, People's Republic of China.
Infect Dis Poverty. 2021 Nov 16;10(1):133. doi: 10.1186/s40249-021-00918-0.
Severe fever with thrombocytopenia (SFTS) caused by SFTS virus (SFTSV) was a tick-borne hemorrhagic fever that posed significant threat to human health in Eastern Asia. The study was designed to measure the seroprevalence of SFTSV antibody in healthy population residing in a high endemic region.
A cohort study was performed on healthy residents in Shangcheng County in Xinyang City from April to December in 2018, where the highest SFTS incidence in China was reported. Anti-SFTSV IgG was measured by indirect enzyme-linked immunosorbent assay and neutralizing antibody (NAb) was detected by using PRNT50. The logistic regression models were performed to analyze the variables that were associated with seropositive rates.
Totally 886 individuals were recruited. The baseline seroprevalence that was tested before the epidemic season was 11.9% (70/587) for IgG and 6.8% (40/587) for NAb, which was increased to 13.4% (47/350) and 7.7% (27/350) during the epidemic season, and further to 15.8% (80/508) and 9.8% (50/508) post epidemic. The IgG antibody-based seropositivity was significantly related to the patients aged ≥ 70 years old [adjusted odds ratio (OR) = 2.440, 95% confidence interval (CI): 1.334-4.461 compared to the group of < 50 years old, P = 0.004], recent contact with cats (adjusted OR = 2.195, 95% CI: 1.261-3.818, P = 0.005), and working in tea garden (adjusted OR = 1.698, 95% CI: 1.002-2.880, P = 0.049) by applying multivariate logistic regression model. The NAb based seropositivity was similarly related to the patients aged ≥ 70 years old (adjusted OR = 2.691, 95% CI: 1.271-5.695 compared to the group of < 50 years old, P = 0.010), and recent contact with cats (OR = 2.648, 95% CI: 1.419-4.941, P = 0.002). For a cohort of individuals continually sampled with 1-year apart, the anti-SFTSV IgG were maintained at a stable level, while the NAb level reduced.
Subclinical infection might not provide adequate immunity to protect reinfection of SFTSV, thus highlighting the ongoing threats of SFTS in endemic regions, which called for an imperative need for vaccine development. Identification of risk factors might help to target high-risk population for public health education and vaccination in the future.
由发热伴血小板减少综合征病毒（SFTSV）引起的严重发热伴血小板减少综合征（SFTS）是一种虫媒出血热，对东亚地区的人类健康构成重大威胁。本研究旨在测量居住在高流行地区的健康人群中 SFTSV 抗体的血清流行率。
2018 年 4 月至 12 月，对信阳市商城县的健康居民进行了一项队列研究，该地区是中国 SFTS 发病率最高的地区。采用间接酶联免疫吸附试验（ELISA）检测抗 SFTSV IgG，采用 PRNT50 检测中和抗体（NAb）。采用 logistic 回归模型分析与血清阳性率相关的变量。
共招募了 886 人。在流行季节前进行的基线血清流行率检测结果为 IgG 阳性率为 11.9%（70/587），NAb 阳性率为 6.8%（40/587），在流行季节上升至 13.4%（47/350）和 7.7%（27/350），随后在流行季节后进一步上升至 15.8%（80/508）和 9.8%（50/508）。基于 IgG 的血清阳性率与年龄≥70 岁的患者显著相关（调整后的优势比[OR]：2.440，95%置信区间[CI]：1.334-4.461，与年龄<50 岁的患者相比，P=0.004）、最近接触猫（调整后的 OR：2.195，95%CI：1.261-3.818，P=0.005）和茶园工作（调整后的 OR：1.698，95%CI：1.002-2.880，P=0.049）。采用多变量 logistic 回归模型，NAb 阳性率也与年龄≥70 岁的患者显著相关（调整后的 OR：2.691，95%CI：1.271-5.695，与年龄<50 岁的患者相比，P=0.010）和最近接触猫（OR：2.648，95%CI：1.419-4.941，P=0.002）。对连续 1 年采样的队列进行分析，抗 SFTSV IgG 水平保持稳定，而 NAb 水平降低。
亚临床感染可能无法提供足够的免疫保护以防止 SFTSV 的再次感染，这突出表明 SFTS 在流行地区仍存在持续威胁，这迫切需要开发疫苗。确定危险因素可能有助于今后针对高危人群开展公共卫生教育和疫苗接种工作。
