Analysis of Differences in Characteristics of High-Risk Endemic Areas for Contracting Japanese Spotted Fever, Tsutsugamushi Disease, and Severe Fever With Thrombocytopenia Syndrome

Takahisa Ogawa; Shinya Tsuzuki; Hiroyuki Ohbe; Hiroki Matsui; Kiyohide Fushimi; Hideo Yasunaga; Satoshi Kutsuna

doi:10.1093/ofid/ofae025

Analysis of Differences in Characteristics of High-Risk Endemic Areas for Contracting Japanese Spotted Fever, Tsutsugamushi Disease, and Severe Fever With Thrombocytopenia Syndrome

Open Forum Infect Dis. 2024 Jan 16;11(2):ofae025. doi: 10.1093/ofid/ofae025. eCollection 2024 Feb.

Authors

Takahisa Ogawa^{1

2}, Shinya Tsuzuki^{3

4}, Hiroyuki Ohbe⁵, Hiroki Matsui⁵, Kiyohide Fushimi², Hideo Yasunaga⁵, Satoshi Kutsuna⁶

Affiliations

¹ Department of Orthopedic, Saku General Hospital Saku Medical Center, Nagano, Japan.
² Department of Health Policy and Informatics, Tokyo Medical and Dental University, Tokyo, Japan.
³ Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan.
⁴ Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.
⁵ Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, Tokyo, Japan.
⁶ Department of Infection Control and Prevention, Graduate School of Medicine, Faculty of Medicine, Osaka University, Osaka, Japan.

Abstract

Background: Tick-borne infections, including tsutsugamushi disease, Japanese spotted fever, and severe fever with thrombocytopenia syndrome (SFTS), are prevalent in East Asia with varying geographic distribution and seasonality. This study aimed to investigate the differences in the characteristics among endemic areas for contracting each infection.

Methods: We conducted an ecologic study in Japan, using data from a nationwide inpatient database and publicly available geospatial data. We identified 4493 patients who were hospitalized for tick-borne infections between July 2010 and March 2021. Mixed-effects modified Poisson regression analysis was used to identify factors associated with a higher risk of contracting each tick-borne disease (Tsutsugamushi, Japanese spotted fever, and SFTS).

Results: Mixed-effects modified Poisson regression analysis revealed that environmental factors, such as temperature, sunlight duration, elevation, precipitation, and vegetation, were associated with the risk of contracting these diseases. Tsutsugamushi disease was positively associated with higher temperatures, farms, and forests, whereas Japanese spotted fever and SFTS were positively associated with higher solar radiation and forests.

Conclusions: Our findings from this ecologic study indicate that different environmental factors play a significant role in the risk of transmission of tick-borne infections. Understanding the differences can aid in identifying high-risk areas and developing public health strategies for infection prevention. Further research is needed to address causal relationships.

Keywords: ecologic study; mixed-effect model; tick-borne disease.