Vol.74 No.2 March 2026

Concurrent Covid-19 and Japanese spotted fever in Japan

Fumiyoshi Murakami¹⁾, Kaori Kashino²⁾, Nana Takayama¹⁾, Yuka Ogawa¹⁾, Kazuko Okazaki¹⁾, Morito Sugimoto³⁾, Tomomi Utsumi⁴⁾, Masahiro Okada¹⁾, Shinya Okamoto¹⁾, Kengo Banshouya^{5, 6)}, Eisuke Takei¹⁾ and Yuuki Satou⁵⁾

¹⁾Department of Pharmacy, Onomichi Municipal Hospital, 3-1170-177 Shintakayama, Onomichi, Hiroshima, Japan
²⁾Department of Dermatology, Onomichi Municipal Hospital
³⁾Department of Urology, Onomichi Municipal Hospital
⁴⁾Department of Nursing, Onomichi Municipal Hospital
⁵⁾Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University
⁶⁾Research Center for Green Science, Fukuyama University

Abstract

COVID-19 is a viral disease that emerged in 2019 and is currently endemic in Japan, with no seasonal variations in the incidence. On the other hand, Japanese spotted fever (JSF) is a tick-borne rickettsial infection that increases in incidence in early summer and early autumn, and the number of cases is increasing every year. We report the case of a patient who was simultaneously diagnosed as having COVID-19 and JSF. The patient was a 60-year-old man who was hospitalized with high fever, and rashes. The SARS-CoV-2 PCR test was positive, based on which the patient was diagnosed as having COVID-19 and started on treatment with remdesivir. In addition, based on his symptoms, we suspected that the patient also concurrently had JSF and started him on treatment with minocycline and levofloxacin. Examination of the eschar and blood returned positive results for Rickettsia japonica, confirming the diagnosis of JSF. It has been pointed out that COVID-19 and JSF may cause similar rashes, so that a careful medical history and diagnosis are necessary.

Key word

COVID-19, Japanese spotted fever, erythema, tick-borne disease

Received

June 10, 2025

Accepted

December 4, 2025

Jpn. J. Chemother. 74 (2): 187-191, 2026