Japanese spotted fever is an infectious disease caused by the bacterium Rickettsia japonica, transmitted to humans through bites from infected hard ticks (Ixodidae) [1][2]. It is classified as a category IV notifiable infectious disease under Japan's Infectious Diseases Control Law [1].
Disease overview
BacterialJapanese spotted fever
日本斑点热
Evidence-backed informationEN 5/7 applicable sections · ZH 5/7 applicable sectionsUpdated Sep 3, 2026
Japanese spotted fever is a spotted fever rickettsiosis caused by Rickettsia japonica, transmitted through bites from infected hard ticks during outdoor activities [1][2]. The disease is classified as a category IV infectious disease in Japan, requiring mandatory reporting of all cases under the Law Concerning the Prevention of Infectious Diseases and Medical Care for Patients of Infections [1]. Clinical manifestations include headache, malaise, high fever, and a red maculopapular rash that typically begins on the extremities and spreads to the trunk, along with eschar formation [1][2]. Severe or fatal cases can occur, and the incubation period ranges from approximately 2 to 8 days after a tick bite [2].
Read the full clinical and epidemiological profile6
The illness typically presents with headache, malaise, and high fever following an incubation period of about 2 to 8 days after a tick bite [2]. A characteristic red maculopapular rash develops, which tends to spread from the extremities to the trunk [1][2]. Eschar formation at the bite site is an important clinical sign, along with fever and rash [1]. Laboratory abnormalities may be observed, and the disease can progress to severe or fatal cases [1][2]. Notably, Japanese spotted fever is characterized by a shorter incubation time and smaller eschar compared to scrub typhus [1].
In Japan, reported cases of Japanese spotted fever increased from 49 to 129 annually between 2006 and 2009 [1]. Reporting has been concentrated in western Pacific-side prefectures, with new endemic areas continuously identified [1]. The disease is considered endemic in Japan as a representative rickettsiosis, and this trend of increasing cases and expanding geographic distribution raises public health concerns [1].
Japanese spotted fever is acquired through bites from infected hard ticks (Ixodidae) during outdoor activities [1][2]. The tick serves as both the vector and reservoir for Rickettsia japonica [1].
Prevention focuses on avoiding tick bites during outdoor activities in endemic areas [1][2]. The National Institute of Infectious Diseases emphasizes that appropriate information for local residents and medical facilities is necessary for infection prevention and timely treatment [1]. Epidemiological analysis supports targeted public health communication to at-risk populations [1]. Physicians are required to notify cases meeting the specified clinical and laboratory criteria under Japan's Infectious Diseases Control Law [2].
- 1Japan National Institute of Infectious Diseases. IASR 31-5 scrub typhus, Japanese spotted fever, NESID, Orientia tsutsugamushi, Rickettsia japonica, Rickettsia heilongjiangensis, laboratory confirmation [Internet]. cited 3 Sept 2026.Available from: https://idsc.niid.go.jp/iasr/31/363/tpc363.html
- 2Japan Ministry of Health, Labour and Welfare. ú{gÁMbú¶JÈ [Internet]. cited 3 Sept 2026.Available from: https://www.mhlw.go.jp/bunya/kenkou/kekkaku-kansenshou11/01-04-23.html
- A77.0
- 1C30.0
Coverage
Reporting countries and regions
Trends by reporting country
Monthly patterns over time
Data access
Page dataset index with source links and update metadata.
Official sourcesAuthority, cadence, notes1
JP NIID Weekly
Japan
Japan weekly infectious disease surveillance via NIID/JIHS.