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

Laboratory and Epidemiology Communications

Annual Incidence of Tsutsugamushi Disease Caused byDifferent Serotypes of Orientia tsutsugamushi inMiyazaki Prefecture in 1 991 ll 999
Seigo Yamamoto*, Kazuhiro Kizoe, Sytlji Yoshino and Toshikatsu Hagiwaral

Miyazaki Prefectural Institute for Public Health and Environment,
Gakuenkibanadai‑Nishi 2‑3‑2, Miyazaki 889‑21 55 andJNational Institute ofInfectious Diseases,
Shinjuku‑ku. Too/0 I 62‑8640
Communicated by Motohiro Kato(Accepted June 22, 2000)

There was a rapid increase of Orientia tsutsugamushi(A)

infection in various parts of Japan in the latter half of theNo. of p血tLta

1970'S (1). Also in Miyazaki Prefecture, the incidence of120

infection started to increase around 1980, and, in 1985, 189100

cases were reported. We report here the annual incidence of
0. tsutsugamushi in 1991 ‑1999 in Miyazaki Prefecture.
IgM and IgG antibodies were assayed by indirect immuno‑

80'1

flu?rescent antibody technique (2) by using the standard
40

stralnS (Gilliam, Karp and Kato strains) and clinical isolatesofKawasaki and Kuroki strains asantigens. All strains were20

gFOwninL929 cells. Kawasakiand Kuroki strains were isolated
0in198 I in Miyazaki Prefectヮre (3‑4)･Anincreaseinantibody

l111..Ill1991 1992

titers during disease progression Or a Single acute phase serum,

1993

1994

1995

1qq占

1明け

1998

1999

f58Cd yW

whose IgM titer was higher than 1 :40 and also higher thanthe IgG titer, were both used as criteria for confirmed cases.
If a serum sample produced atiter to a particularantigenthat
was doublethat of otherantigens,the serum was considered tobe specific to the antigen.
Casesfu1filIing the followlng Criteria were considered to beclimical Tsutsugamushi disease, even if the serum wasantibody‑(a)No. a p血nts

60

5040
30

negative, i.C., if fever and rash and/Or a lesion from a mite
20

bite were observed,and if the onset of disease was from October
to February, and if the serum was obtained within 10 days

10

after the onset of disease.
0A total of 679 cases were reported in the period between

1991

April of 1991 to March or 1999. Among them, 576 cases
were confirmed by serodiagnosis (Fig. lA). Three hundred1992

1993

1994

1995

1996

1997

1998

1999
Fi書Cd year

Fig. I. Annual incidence of Tsutsugamushi disease in Miyazaki
Prefecture. (A) Sumtotalof clinical and confirmed cases (open bars)
and con丘rmed cases (closed bars). (B) The incidence according toserotypes; sera reactingwith Kawasaki type(closed bars), sera

Table. Monthlyfluctuation of Tsutsugamushi disease in Miyazaki
Prefecture in 1991‑1999

托aC血gwith Kuroki type(shaded bars)and sera FeaCtingwithmultiple

antigens (open bars).

Antigenic Type Kawasaki Kuroki Multiple Reactive
September

0 7 0ノ 4 0 1 0 0OctoberNow ember

0 2 0ノ 2 1 2 tJ 0l つJ 9 0 7 ′‑Ul 1

1 00 42111

seventy‑one (64%)people were infectedwith Kawasaki typel12 1and 166 (29%) with Kuroki type; infections inthe remaining

December

39 patients were difficult to classify because the sera reacted

January

with multiple antigens (forthe classification of this last group,February

genomic analysis of isolates was necessary) (Table). In 1 985‑

March1988, 74% of the patients were infected by Kawasakitype

April
Tbta1

and 22% by Kuroki type (2). Therefore, the overall pattem of37

11

infection has remained unchanged in the past I 5 years. The66

fluctuation of the total incidence was largely innuenced by*Corresponding author: Fax: +8 1 1985‑58‑0930

仇at of Kawasaki type. Kuroki type was less common in126

Jpn. J. Infect. Dis., 53, 2000
No. dpdenb

and December (Table). Seventy‑three percent of the patients

12

were more than fifty years of age, reflecting the average age

10orthe population in the endemic reglOn.

86REFERENCES

42I. Kawamura, A., Jr. (1995): Seasonal prevalence of the0disease in Japan and neighboring countries. p. 10‑ 17. In
8 7 丘V 5 4 lJ 'l 1 0

Kawamura, A., Jr., Tanaka, H.and Tamura, A. (eds.),
Tsutsugamushi Disease. Tokyo UniversityPress, Tokyo･
2. Yamamoto, S., Kawabata, N., Ooura, K., Murata, M. andMinamishima, Y. (1 989): Antigenic types ofRickettsia
tsutsugamushi isolated from patients with Tsutsugamushifever and their distribution in Miyazaki Prefecture. J. Jpn.
1991

1992

1993

1994

1995

1996

1997

1998

Assoc. Infect. Dis., 63,109‑1 17 (in Japanese).

1999

3. Yamamoto, S., Kawabata, N., Tamura, A., Urakami, H.,Ohashi, N., Murata, M., Yoshida, Y. and Kawamura, A.,

Fiscd yeiLr

Fig. 2. Annual incidence orTsutsugamushi disease in two endemicareas in Miyazaki Prefecture, the area! of Kobayashi (A) andMiyakonojo (B). Closed bars: sera reactlng With Kawasaki type;
Shaded bars: sera reactingwithKuroki type; open bars: sera reacting

Jr. (1986): Immunological properties of Rickettsia

tsutsugamushi, Kawasaki strain, isolated from a patientin Kyushu. Microbiol. Immunol. 30, 61 1‑620･
4. Ohashi, N., Tamura, A., Sakurai, H. and Yamamoto, S.

with multiple antlgenS.

( I 990): Characterization ofa newantigemic type, Kuroki,of Rickettsia tsutsugamushi isolated from patients ingeneral, but was relatively frequent in 1993, 1998, and 1999

J叩an. ∫. Clin. Microbiol･ 28, 211ト2113･(Fig. 1B).

There are two regions, Kobayashi and MiyakonoJO,

5. Ohashi, N., Koyama, Y, Urakami, H., Fukuhara, M.,

endemic for Tsutsugamushi disease. However, the armual

Tamura, A., Kawamori, F., Yamamoto, S., Kasuya, S.
and Yoshimura, K. (1996): Demonstration of antigenic

nuchation was not identical in仇e two regions (Fig･ 2)･ It is

probable that the distribution and/or propagation ofvariation in Orientia tsutsugamushi which were isolated

Leptoty10mbidium scute/lwe, aknOwn vector of Kawasaki andin Japan, and their classification intotype and subtype･
Microbiol. Immunol. 40, 627‑638.

Kuroki types of 0. tsutsugamushi (5), differed in these two
reglOnS. The patients were diagnosed in a cluster in November

Laboratory and Epidemiology Communications

Acute Hepatitis Outbreak in Tokyo Caused by Hepatitis A Virus ofCommon Origin Transmitted through Oral and Sexual Routes
Masashi Baba, Hiroyuki Oka, MasakoAsayama, Syuya Yoshinaga, Hiroko Yamashita,
Natsuo Tachikawal, Jun‑ichi Akiyama, Akira Yasuokal, Shin‑ichi Okal, ShigeruYamato,

Ryosuke Shoda, ToruMuraoka, Naohiko Masaki, Kei Matsueda,
Emi Shimqo and Shigeki Hayashi*
Department ofGastroenterology and JAIDS Therapy and Research Cente7;International Medical Center ofJapan,

Toyama 1‑21‑1, Shinjuku‑ku, Too,0 162‑8655
Communicated by Hiroshi Yoshikura(Accepted June 22, 2000)

national hospitals in 1990 and 115 cases were reported inHepatitis A virus (HAV) is transmitted by fecal‑Oral routes･Outbreaks can occur in families (1) and among homosexuals

1991. The number ofHAV cases gradually declined a鮎r 1991

and in 1995‑1998, only 20‑50 cases were reportedannually.

(2). Infection acquired byingestion of infected clams or oysters
is aequent (3). Japan experienced large outbreaks in 1990and1991. One hundred and eighty‑seven cases were reported at

In 1 999,anunusually large number ofHAV‑infected patients
visited our clinic: three patients were seen in January‑March,four patients in May‑June, five patients in July‑September,and two patients in October‑December. Patients'clinical*Corresponding author: E‑mail : shayashi@imcj ･ hosp. go･jp

127