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

Laboratory and Epidemiology Communications

The First Reported Case of a Dog Infected withEchinococcus multilocularis in Saitama Prefecture, Japan
Norishige Yamamoto*, Yasuyuki Morishima2, Marina Kon, Masanori Yamaguchi, Sakiko Tanno,
Masaya Koyama1, Naohiro Maeno1, Hisashi Azuma1, Hajime Mizusawa1, Hiroshi Kimura1,
Hiromu Sugiyama2, Kyoko Arakawa2 and Masanori Kawanaka2
Saitama Institute of Public Health, Saitama 338-0824;
Saitama Prefectural Pet Owner’s Guidance Center, Saitama 360-0105; and2
Department of Parasitology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan1

Communicated Takuro Endo
(Accepted September 29, 2006)
Echinococcus multilocularis is a causative agent of humanalveolar hydatidosis. The distribution of the parasite in Japanis thought to be limited to Hokkaido, the northernmost insularprefecture. The life cycle of this parasite is predominantly

sylvatic. In Hokkaido, the red fox (Vulpes vulpes) is a definitive host that excretes E. multilocularis eggs into its feces. The
gray-sided vole (Clethrionomys rufocanus) is a principal
intermediate host that becomes infected by ingesting the eggs,
which develop into larvae in the host viscera. Domestic dogs
also become definitive hosts of the parasite after eating voles
harboring the larvae. Since human infections follow theaccidental ingestion of E. multilocularis eggs, a survey ofE. multilocularis infection in dogs is a crucial for disease*Corresponding author: Mailing address: Saitama Institute of
Public Health, 639-1 Kamiokubo, Sakura-ku, Saitama 338-0824,
Japan. Tel: +81-48-853-5047, Fax: +81-48-840-1041, E-mail:a0143386@pref.saitama.lg.jp351

isolates from Hokkaido (GenBank accession no. AB244598).
These results showed that this dog was infected with E.
multilocularis.
The source of infection was not identified. No convincing
evidence yet supports the notion that wild animals in Saitama
and its neighboring prefectures are infected. Since some dogs
that move from Hokkaido to the mainland of Japan are
infected (2), the dog described herein seems to have been
infected in Hokkaido, then taken to Saitama by her owner, andthen either abandoned or allowed to escaped. Regardless, anextensive epizootiological survey should be conducted on wild
animals in suspect areas of the prefecture. The Infectious
Diseases Control Law of Japan has classified the significanceof this disease to public health as Category IV, which has
required the mandatory reporting of not only infected humans
but also infected dogs since October 1, 2004. In accordancewith this law, this is the first reported instance of a dog
infected with E. multilocularis in a Japanese prefecture otherthan Hokkaido.

prevention. Data obtained from an examination of 9,907 dogsin Hokkaido between 1966 and 2004 by the prefectural
government revealed that 99 (1.0%) were infected with theadult parasites. The estimated number of dogs that travelfrom Hokkaido to other prefectures is over 12,000 per year(1). Some of these dogs might constitute important carriers,transmitting the parasite to remote areas. Morishima et al.
(2) recently studied the extent of E. multilocularis infectionin 183 dogs transported by their owners from Hokkaido
to other prefectures and found that two of the dogs wereinfected. Here we describe the first case of a dog infectedwith E. multilocularis in Saitama Prefecture, which neighbors northern metropolitan Tokyo.
The dogs examined in this survey were abandoned andpound animals. A total of 550 dogs kept in the Saitama
Prefectural Pet Owner’s Guidance Center were examined
between April 1999 and September 2005. Staff members at
the center collected fecal samples. These were routinely
checked for the presence of helminth eggs and protozoan
oocysts by microscopy using direct smear, formalin-ether andsucrose flotation techniques. Taeniid eggs (Fig. 1) were foundin a fecal sample from a female mongrel dog that was captured
in northern Saitama in June 3, 2005. Because Echinococcus
eggs are morphologically indistinguishable from those ofother tapeworms of the family Taeniidae (3), they wereexamined by PCR according to the method of Dinkel et al.
(4). The second round of nested PCR produced a single bandof the predicted size at 250 bp. Direct sequencing showedthat the band was the same as those found in E. multilocularis

This article appeared in the Infectious Agents Surveillance
Report (IASR), vol. 26, p. 307-308, 2005 in Japanese.
REFERENCES
1. Doi, R., Matsuda, H., Uchida, A., Kanda, E., Kamiya,
H., Konno, K., Tamashiro, H., Nonaka, N., Oku, Y.
and Kamiya, M. (2003): Possibility of invasion ofEchinococcus multilocularis into Honshu with pet dogs
from Hokkaido and overseas. Jpn. J. Public Health, 50,639-649 (in Japanese with English summary).
2. Morishima, Y., Sugiyama, H., Arakawa, K. and Kawanaka,
M. (2006): Echinococcus multilocularis in dogs, Japan.
Emerg. Infect. Dis., 12, 1292-1294.
3. Thompson, R.C.A. and McManus, D.P. (2001): Aetiology: parasites and life-cycles. p 1-19. In Eckert, J.,Gemmell, M.A., Meslin, F.-X., Pawlowski, Z.S. (ed.),
WHO/OIE Manual on Echinococcosis in Humans andAnimals: a Public Health Problem of Global Concern.
World Organization for Animal Health, Paris.
4. Dinkel, A., von Nickisch-Rosenegk, M., Bilger, B., Merli,M., Lucius, R. and Romig, T. (1998): Detection of Echinococcus multilocularis in the definitive host: coprodiagnosis
by PCR as an alternative to necropsy. J. Clin. Microbiol.,36, 1871-1876.

Fig. 1. Echinococcus multilocularis egg found in the fecal sample of adog captured in Saitama Prefecture, Japan. Scale bar equals 30 μm.

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