Analysis of clinical features and pathology of severe fever with thrombocytopenia syndrome in Japan

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K08931
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 54030:Infectious disease medicine-related
• Research Institution: Ehime University
• Principal Investigator: Suemori Koichiro 愛媛大学, 医学系研究科, 准教授 (80571083)
• Co-Investigator(Kenkyū-buntansha): 安川 正貴 愛媛県立医療技術大学, 保健科学部, 教授 (60127917)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: SFTS / 異型リンパ球 / ファビピラビル

Outline of Final Research Achievements

During the study period, eight patients with severe febrile thrombocytopenia syndrome (SFTS) were delivered in Ehime prefecture, of which 3 (2 severe and 1 mild) were admitted to our hospital. Atypical lymphocytes were found in peripheral blood, and flow cytometric analysis showed that B cells were significant in severely ill patients, while T cells were significant in mildly ill patients. From April to December 2016 and from September 2017 to May 2018, favipiravir was administered as a new antiviral drug for SFTS for 7 to 14 days in a doctor-led clinical trial mainly at medical institutions in western Japan. The analysis was performed in our hospital. Twenty-three were enrolled in this study, 19 survived and 4 died (mortality rate 17.4%). Only previously reported adverse events were found, and no new adverse events were observed.

Free Research Field

感染症

Academic Significance and Societal Importance of the Research Achievements

SFTS患者の末梢血を用いた解析からは、異型リンパ球がT細胞有意（通常のウイルス感染症と同様の免疫反応）であれば軽症であり、B細胞有意であれば重症の病態である可能性が示唆された。これらの所見は今後の診断および治療の発展に寄与する知見と思われる。医師主導型臨床試験で得られたファビピラビルの有効性と安全性についての解析は、現在、抗ウイルス薬が存在しないSFTSにおいて、治療薬として有効性が期待される結果であり、実臨床で使用できるポテンシャルが高い薬剤であることが示唆された。