Abstract: Objective To investigate the basic characteristics of patients with severe fever with thrombocytopenia syndrome (SFTS) and risk factors for occurrence and death of SFTS in Wendeng district, Weihai, Shandong province, China, and to provide scientific evidence for precise control and prevention of this disease. Methods A field investigation was carried out to collect the clinical and epidemiological information of the cases, and the specimens from healthy people, animals, and ticks. The virus-specific nucleic acids and antibodies were measured by quantitative real-time PCR and ELISA. The statistical differences in positive rate of antibodies between specimens of different features were determined. Results The three death cases presented with systemic symptoms including high fever, fatigue, and anorexia in the early stage, followed by consciousness disturbance and hemorrhagic manifestations in the late stage. The time interval from disease onset to death was shorter than 10 days. All the 3 cases were elderly women aged 65 years or older living in different areas of the same village, and they had no epidemiological associations. A total of 169 serum specimens from healthy people were collected. All the serum specimens were negative for IgM antibody, and 4.14% of them were positive for IgG antibody. There was a significant difference in the positive rate of IgG antibody between different age groups (χ²=6.987, P=0.030), and the positive rate of IgG antibody increased with age. Among 69 animal blood specimens, the overall positive rates of antibodies in blood specimens from sheep and dogs were 32.14% and 20.00%, respectively, while the antibodies were negative in blood specimens from raccoon dogs, chickens and cats. There was a significant difference in the positive rate of antibodies between different animals (χ²=13.263, P=0.010). The virus-specific nucleic acids were negative in all the animal blood specimens. Six ticks (one questing tick and five on-host ticks) were captured and identified as Haemaphysalis longicornis, negative for virus-specific nucleic acids. Conclusion This investigation has an important enlightenment on understanding the epidemiological characteristics of SFTS. Further research should be conducted to investigate transmission routes, pathogenic features, and risk factors for onset and death of this disease. Health promotion and education should be strengthened among the key population to raise awareness of disease prevention in key areas during high-incidence seasons.

Key words: Severe fever with thrombocytopenia syndrome, Serology, Clinical and epidemiological characteristics

摘要： 目的 调查威海市文登区发热伴血小板减少综合征病例的基本特征以及发病和死亡的危险因素，为其精准防控提供科学依据。方法 采用现场调查的方法，收集病例的临床和流行病学信息；采集同村健康人、动物和蜱标本，采用实时荧光定量PCR和ELISA方法，检测病毒特异性核酸和抗体，比较不同特征标本的抗体阳性率差异是否有统计学意义。结果 3例死亡病例的临床表现早期主要为高热、乏力、厌食等全身反应，后期有意识障碍和出血表现，从发病到死亡的时间间隔均短于10 d。3例病例均为65岁以上老年女性，居住在同一村庄的不同位置，无流行病学关联。共采集169份健康人血清标本，IgM抗体检测均为阴性，IgG抗体阳性率为4.14%，各年龄组IgG抗体阳性率差异有统计学意义（χ²=6.987，P=0.030），年龄越大抗体阳性率越高。共采集69份动物血标本，羊和犬血标本总抗体阳性率分别为32.14%和20.00%，貉子、鸡、猫血标本抗体检测均为阴性，不同动物抗体阳性率差异有统计学意义（χ²=13.263，P=0.010）；病毒特异性核酸检测均为阴性。捕获蜱6只，其中游离蜱1只，寄生蜱5只，均为长角血蜱，病毒特异性核酸检测也均为阴性。结论 该次事件的调查对认识疾病的流行特征具有重要的启示作用，应进一步加强疾病传播途径、病原学特性、发病死亡危险因素等方面研究，重点地区高发季节应加强重点人群的健康宣传教育，提高防病意识。

关键词: 发热伴血小板减少综合征, 血清学, 临床和流行特征