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

Laboratory and Epidemiology Communications

Scrub Typhus (Tsutsugamushi Disease) in Kanagawa Prefecture in 2001 - 2005
Takashi Katayama*, Miyuki Hara, Yumiko Furuya, Takayasu Nikkawa and Hirokazu Ogasawara1
Department of Biology, Kanagawa Prefectural Institute of Public Health, Kanagawa 253-0087 and1
Division of Health Promotion, Department of Public Health and Welfare,
Kanagawa Prefectural Government, Yokohama 231-8588, Japan
Communicated by Ichiro Kurane(Accepted May 8, 2006)

Until 1988, about 10 cases of scrub typhus (tsutsugamushidisease) were reported annually in Kanagawa Prefecture.
Since then, however, a steep cycle of rising and falling hasensued. Cases jumped to 81 in 1989 and 112 in 1990, thendeclined to only 9 in each of 1996 and 1997. Increases began
again in 1998, peaking at 42 in 2000, followed by 7 in 2001,
4 in 2002, and 10 in 2003. In 2004 and 2005 there were 18and 19 cases, respectively (1-3).
We examined 87 cases of suspected of scrub typhus occurring in 2001 - 2005 (13, 7, 17, 23, and 27 cases from 2001 - 2005,respectively) for serum antibody by immunofluorescence (IF)assay (4) and for Orientia tsutsugamushi DNA by PCR (5).
Among them, 58 were confirmed as scrub typhus (7, 4, 10,18, and 19, respectively) (Table 1).
From the scrub typhus cases in 2001 and 2003, a total of 5
O. tsutsugamushi isolates were obtained (1,2). Four of these
isolates were obtained from patients infected in Kanagawa
Prefecture, and the remaining one was obtained from apatient presumably infected in Korea. Typing by PCR and IF
assay using monoclonal antibodies revealed that the fourKanagawa Prefecture isolates consisted of one Karp-typestrain, two Kawasaki-type strains, and one Kuroki-type strain,
and that the isolate of the Korea case was a Kuroki-type strain.
The sequence of the 56-kDa protein gene of the Karp-type
isolate was identical to that of the Jp2 type.
Using PCR, we tried to type the O. tsutsugamushi present
in the patients’ blood specimens (5). For specimens whosegenomes were not detected, the type was assessed by theIF method. We found that the O. tsutsugamushi that caused
infection in Kanagawa Prefecture and in the nearby region ofShizuoka Prefecture was either Karp type (4 cases, 7%),Kawasaki type (37 cases, 69%), or Kuroki type (13 cases,24%). The majority of cases were Kawasaki type. The Karpand Kuroki types were less common, but the incidence of theTable 1. Detection of immunofluorescence antibody andO. tsutsugamushi DNA by PCR
No. of positive samples
IFIF and PCR
PCR

Year

No. ofsamples

Confirmedcases

2001
2002
2003
2004
2005

13
7
1723
27012
46*

737
13
1300110741018
19

Total87

1343258All the samples were tested by IF and PCR except one that wastested only by IF (marked with asterisk).
Table 2. Types of O. tsutsugamushi detected in comfirmed cases
Strain typeKawasakiNo. ofsamples

Karp2001
2002
2003
2004
2005

74
8
17
18

20
1
1043
6
11
13

1
1
1
55Total (%)

544 (7)37 (69)13 (24)Year

Kurokilatter tended to increase in the most recent years (Table 2).
The suspected places of infection are plotted in Fig. 1A.
They are clustered on the western side (the Shizuoka Prefecture side) of Kanagawa Prefecture. Each region was infested
by more than one type (Fig. 1B). Infections were most frequent in October, November, and December, with a peakin November. In 2005, however, an infection in March wasobserved.
The recent trend of scrub typhus appears to be characterized by alternating high and low incidence periods, eachlasting 2 to 3 years. What factors are causing the fluctuationis unknown. The natural history of the pathogen itself, thevector mites and reservoir animals, and possibly climate*Corresponding author: Department of Biology, Kanagawa Prefectural Institute of Public Health, Shimomachiya 1-3-1, Chigasakishi, Kanagawa 253-0087, Japan. Tel: +81-467-83-4400, Fax:+81-467-83-4457, E-mail: katayama.zups@pref.kanagawa.jp
207Fig. 1. Scrub typhus infectious area in Kanagawa Prefecture (2001 - 2005).

change may all be important determinants. As scrub typhus
is curable with appropriate chemotherapy, early diagnosis
is very important. IF and PCR are useful methods for early
confirmatory diagnosis.

Imai, M. (2004): Occurrence of tsutsugamushi diseasein Kanagawa Prefecture (2002, 2003). Bull. Kanagawa
Inst. Public Health, 34, 40-41 (in Japanese).
3. Katayama, T., Furuya, Y., Takahashi, T. and Nikkawa, T.
(2005): Occurrence of tsutsugamushi disease in Kanagawa
Prefecture (2004). Bull. Kanagawa Inst. Public Health,35, 27-29 (in Japanese).
4. Yamamoto, S., Kawabata, N., Ooura, K., Murata, M. andMinamishima, Y. (1989): Antigenic type of Rickettsia
tsutsugamushi isolated from patients with tsutsugamushifever and their distribution in Miyazaki Prefecture. J. Jpn.
Assoc. Infect. Dis., 63, 109-117 (in Japanese).
5. Yoshida, Y., Furuya, Y., Katayama, T., Kaiho, I. andYamamoto, S. (1994): Serotype-specific amplificationof Rickettsia tsutsugamushi DNA from clinical specimens by nested polymerase chain reaction. J. Jpn. Assoc.
Infect. Dis., 68, 601-606 (in Japanese).

We 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. 29-30, 2006.
REFERENCES
1. Furuya, Y., Katayama, T., Hara, M., Imai, M. and Yoshida,
Y. (2002): Occurrence of tsutsugamushi disease inKanagawa Prefecture (2001). Bull. Kanagawa Public
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