Japanese spotted fever is an infection caused by the bacterium Rickettsia japonica, representing a spotted fever rickettsiosis acquired through the bite of infected hard ticks [1][2]. It is classified among representative rickettsioses in Japan and is subject to mandatory notification [1][2].
Disease overview
Bacterial Evidence-backed information EN 5/7 applicable sections · ZH 5/7 applicable sections Updated Oct 23, 2026
Japanese spotted fever is a representative rickettsiosis in Japan caused by Rickettsia japonica and transmitted through infected hard tick bites during outdoor activity [1][2]. Reported annual cases rose from 49 to 129 between 2006 and 2009, with concentration in western Pacific-side prefectures and identification of new endemic areas [1]. The disease is a category IV notifiable infection under Japanese law, requiring case reporting by physicians [1][2].
Read the full clinical and epidemiological profile 6
Major clinical signs include fever, rash, and eschar, with the rash tending to spread from the extremities to the trunk [1]. Illness may begin two to eight days after a tick bite with headache, malaise, high fever, and a red maculopapular rash starting on the extremities, and severe or fatal progression can occur [1][2].
In Japan, reported cases increased annually from 49 in 2006 to 129 in 2009 [1]. Surveillance data showed concentration of cases in western Pacific-side prefectures and the identification of newly endemic areas during this period [1].
The infection is acquired through bites of infected Ixodidae (hard) ticks during outdoor activities [1][2]. The causative agent is Rickettsia japonica, transmitted by the tick vector rather than by person-to-person spread [1][2].
Prevention relies on epidemiological analysis and provision of appropriate information to local residents and medical facilities to reduce tick exposure during outdoor activity [1]. Strengthened surveillance and public awareness are identified as necessary components for infection prevention and timely response [1].
- 1 Japan National Institute of Infectious Diseases. IASR 31-5 scrub typhus, Japanese spotted fever, NESID, Orientia tsutsugamushi, Rickettsia japonica, Rickettsia heilongjiangensis, laboratory confirmation [Internet]. cited 23 Oct 2026. Available from: https://idsc.niid.go.jp/iasr/31/363/tpc363.html
- 2 Japan Ministry of Health, Labour and Welfare. ú{gÁMbú¶JÈ [Internet]. cited 23 Oct 2026. Available from: https://www.mhlw.go.jp/bunya/kenkou/kekkaku-kansenshou11/01-04-23.html
- A77.0
- 1C30.0
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