Jpn. J. Infect. Dis., 59, 2006

Laboratory and Epidemiology Communications

Epidemiology of Tsutsugamushi Disease andJapanese Spotted Fever in Kagoshima Prefecture, Japan
Mutsuyo Gokuden*, Kanji Ishitani, Ken-ichiro Yoshikuni, Nobuhiro Ueno,
Naomi Shinkawa, Tsuyoshi Kuramoto, Toshiro Honda1 and Yoshihiko Miyata
Kagoshima Prefectural Institute of Environmental Research and Public Health, Kagoshima 892-0853
and 1Izumi Public Health Center, Kagoshima 899-0202, Japan
Communicated by Ichiro Kurane(Accepted May 23, 2006)
prefecture. Further analysis on the geographical distributionof the diseases, the active seasons of the insect vectors andtheir relation to infections in humans, etc., will be necessary
in order to effectively plan preventive measures (3). While
the two infections share similar symptoms, Japanese spotted
fever sometime causes serious complications such as disseminated intravascular coagulation (4 cases among our 48
patients). Since fatal cases of Japanese spotted fever havebeen reported every year in other prefectures, early diagnosis
and early medical treatment are critically important.
Intensified rickettsia control should include the isolationof rickettsiae in Acarina and other ticks parasitizing wildrodents and further investigation on pathogens involved infevers whose origin is unknown using paired serum testing.
Early diagnosis should include not only laboratory diagnosis
such as immunological diagnosis using antigens of rickettsiae
isolated in Kagoshima Prefecture but also polymerase chain
reaction diagnosis.

Tsutsugamushi disease is caused by infection with Orientia
tsutsugamushi, whose vector is a chigger. Japanese spotted
fever is caused by Rickettsia japonica, whose vector isAcarina. Both infections are classified as Category Four infectious diseases under the Japanese Infectious Disease Law(1,2).
In 2004, Kagoshima Prefecture reported 54 cases oftsutsugamushi disease, the highest frequency in Japan,accounting for approximately 18% of the total 296 cases inJapan. Japanese spotted fever cases in Kagoshima Prefecture
numbered 11 in the same year, accounting for 16% of thetotal 67 cases in Japan, and giving the third highest frequencyof all the prefectures.
Our institute conducted serological investigations using
the immunofluorescence (IF) method on 48 tsutsugamushi
patients in 2004 and on 48 Japanese spotted fever patientsfrom 2000 to 2004. The O. tsutsugamushi antigens used werethe standard Kato, Karp and Gilliam strains as well as theKawasaki and Kuroki strains that frequently occur in southwest Japan. For R. japonica, we used an antigen of the YHstrain.
We found that tsutsugamushi disease occurred most frequently from October to April, while Japanese spotted fever
arose most often from April to December. Tsutsugamushi
cases were most frequently seen among people in their 60s,and the male to female ratio was 9:7. Japanese spotted fever
was most prevalent among people in their 70s, and the maleto female ratio was 3:5. For both infections, 90% of thesuspected places of infection were mountainous (60%) andflat (30%) rural areas, and half of the cases were associatedwith agricultural activities.
The Kagoshima Prefecture government has been promoting the prevention of infection through its information services.
Such activities are continuously needed because the risk ofinfection is associated not only with forestry activities but
also with agricultural, leisure and other activities that takeplace in flatland areas and even in residential zones.
Tsutsugamushi disease has been found diffusely in Kagoshima Prefecture, while Japanese spotted fever is generally
localized on the Osumi Peninsula in the eastern part of theWe thank Prof. Hiroshi Yoshikura, Emeritus Researcherof the National Institute of Infectious Diseases, for advice on
preparing the manuscript.
This article appeared in the Infectious Agents Surveillance
Report (IASR), vol. 27, p. 31-33, 2006 in Japanese.
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T. and Uchida, T. (1985): The first report of the rickettsial
infections of spotted fever group in Japan: three clinicalcases. J. Jpn. Assoc. Infect. Dis., 59, 1165-1172 (in Japanese with English summary).
2. Uchida, T., Tashiro, F., Funato, T. and Kitamura, Y.
(1985): Spotted fever group rickettsiosis in Japan. Jpn.
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3. Honda, T., Nakayama, K., Yoshikuni, K., Shinkawa, N.,
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Prefect. Inst. Public Health, no. 4, 58-61 (in Japanese).

*Corresponding author: Mailing address: Kagoshima Prefectural
Institute of Environmental Research and Public Health, 1-24
Shiroyama-cho, Kagoshima 892-0853, Japan. E-mail: gokuden@kg-env.org
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