Jpn. J. Infect. Dis., 53, 2000

Laboratory and Epidemiology Communications

Japanese Spotted Fever in Shimane Prefecture‑ Outbreak and Place of Infection
Asao Itagaki*, Yuho Matsuda and Ken Hoshina
Shimane Prefectural Institute ofPublic Hea/th and Environmental Science
Nishihamasada‑cho 582‑1, Matsue 690‑0122, Japan
Communicated by Hiroo lnouye(Accepted April 28, 2000)

Town and Hirata Cityare located (ngure). It is inhabited by

Japanese spotted fever (JSF, caused by Rickettsiajaponica)

was first discovered by Dr. F. MaharainAnan City, Tokushima

a population of about 46,000.

Prefecture, in 1984 (1). Since then, a total of200 JSF cases

The outbreak of Tsutsugamushi (scrubtyphus, caused byhave been reported in I 0 prefectures. Incidence of this diseaseOrientia tsutsugamushi) occurred in a different place; along

has been higher on the Pacific side of the Japanese Islands,

the Chugoku mountain range, which is separated by the IZumO

from Kagoshima to Chiba (2). However, cases have also been

plain &om the above‑mentioned JSF endemic area. A total ofreported, though rarely, from Shimane Prefecture, On the47 cases have been reported since 1985; the seasonal peaks

opposite side of the Pacific coast.

were in March‑May and October‑November. The Tsutsuga‑

A total of 14 cases in Shimane Prefecture have been reported

mushi endemic area is now expanding toward the JSF

since September 1987 (3). The Table shows the number ofendemic area. Therefore, irrespective of the residential area,cases confirmed by our institute from 1 987‑ 1 999. Though there

tests for both JSF and Tsutsugamushi should be done.

A total of2,713 blood specimenswere obtained in 1988andwere no cases between 1 990 and 1 994, incidence recurred in1995.

1989 from residents 40 years of age or older in Shimane

Prefecture. The specimenswere examined by the indirect nuo‑rescent antibody technique uslng R. japonica YH strain as

The outbreaks were geographically restricted to the areasurrounding the Misen mountain range on the west side of
the Shimane Peninsula (about 6,860 hainsize), where Taisha

the JSF antlgen. The seroposltlVlty Was 0‑5% in most areas.
However, in areas where cases had been previously reported,

it was 6.9%, and in areas where actual infection was supposed

to have taken place, it was 1 1.7%. When blood specimens

Sea of Japan

Pequentially obtained ( I 988‑ 1 992) from the same population･ln One area, Were compared, the positive ratio tended torUlisen Mountain Range

increase gradually･ In sera collected in 1 978, long before thediscovery of JSF (1.984), the antibody was detected (4). The
antibody was also detected in wild mice, wild deer, and hunt‑ing dogs in the area (5).

̲‑I‑‑‑‑‑‑In Shimane Prefecture, JSF infection is frequent in May‑
June and August‑October. The seasons comSpOnd to thehatching of ticks and the agricultural activities of farmers.

‑J･‑

亡でutb･eak area of TSutsugarTIu.Shi ､1一一

一一､

̲̲

̲

一

一一･一

ノPatient age ranged from that of small children to adults 50‑

60 years of age. Various species of ticks considered to transmit
JSF, such as Haemapkysalis spp. and Ixodes spp., have been
confirmed in the infected areas in Shimane Prefecture.

REFERENCES
Figure. Places where JSF patients were fわund.

l･ Mahara, F･, Koga, K., Sawada, S., Taniguti, T., Sigemi,

Numbers indicate patient number.

Table. Japanese spotted fever in Shimane Prefecture
Yearl987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

Inci dence
11

1000001

33

31(number)
Patient
12

3

4

number●'see Figure.

*Co汀eSpOnding author: Fax: +8ト852‑36‑6683

73

5‑78̲101ト13

14

Jpn. J. Infect. Dis., 53, 2000
F., Suto, K., Tsuboi, Y., Oya, A., Koyama, H., Uchiyama,T. and Uchida, T. (1985): The first report oftherickettsial

Shimane Prefecture. J. Jpn.Assoc. Infect. Dig., 64, 136‑

infection of spotted fever group in Japan; three clinical

4. Itagaki, A., Itogawa, H., Hoshina, K., Watanabe, Y･ andcases. J. Jpn.Assoc. Infect. Dis., 59, 1 16511 172 (in Japa‑

Fukushima, H. (1993): Sero and etiologic survey for
spottedfever grouprickettsial infection in Shimane Pre‑
fecture. Special Rep. Shimane Pref. Inst. Public Health141 (in Japanese).

nese).

2. National Institute of Infectious Diseases and Infectious
Diseases Control Division, Ministry of Healthand Welfare

Envrion. S°i., 16‑19 (in Japanese).

5. Hoshina, K., Itogawa, H., Itagaki, A., Gomyoda, M. and(I 999): Japanese spotted fever. Infect･ Agents Surveill
1ance Rep., 20, 211'‑212'.
3. Oka, N., Kato, Y., Dekio, S., Nishio, T., Itagaki, A.,
Uchiyama, T. and Uchida, T. (1990): A case report orUchida, T. (1995): Serosurvey for spotted fever grouprickettsial infection in vertebrates in Shimane Prefecture.

J. Jpn.Assoc. Infect. Dis., 69, 524‑531 (in Japanese)･

spotted fever grouprickettsiosis first encountered in74