Jpn. J. Infect. Dis., 53 (3), 127-129, 2000

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Laboratory and Epidemiology Communications

Acute Hepatitis Outbreak in Tokyo Caused by Hepatitis A Virus of Common Origin Transmitted through Oral and Sexual Routes

Masashi Baba, Hiroyuki Oka, Masasko Asayama, Syuya Yoshinaga, Hiroko Yamashita, Natsuo Tachikawa1, Jun-ichi Akiyama, Akira Yasuoka1, Shin-ichi Oka1, Shigeru Yamato, Ryosuke Shoda, Toru Muraoka, Naohiko Masaki, Kei Matsueda, Emi Shimojo and Shigeki Hayashi*

Department of Gastroenterology and 1AIDS Therapy and Research Center, International Medical Center of Japan, Toyama 1-21-1, Shinjuku-ku, Tokyo 162-8655

Communicated by Hiroshi Yoshikura

(Accepted June 22, 2000)


Hepatitis A virus (HAV) is transmitted by fecal-oral routes. Outbreaks can occur in families (1) and among homosexuals (2). Infection acquired by ingestion of infected clams or oysters is frequent (3). Japan experienced large outbreaks in 1990 and 1991. One hundred and eighty-seven cases were reported at national hospitals in 1990 and 115 cases were reported in 1991. The number of HAV cases gradually declined after 1991 and in 1995-1998, only 20 - 50 cases were reported annually.

In 1999, an unusually large number of HAV-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 profiles and laboratory findings are shown in Tables 1 and 2.

VP1-2A region of HAV was PCR-amplified from ten serum/plasma preparations. Among them, eight sequences (patients 1, 2, 4, 8, 9, 10, 11 and 13) were identical. HAV from patient 7 was different from that of the others, but by only one transitional base change. Thus, these nine patients were considered to have been infected by a strain of HAV of the same origin. The sequence had a homology to the HAV IB group, GBM strain, which caused a large outbreak in Germany in 1997. HAV from patient 3 had a quite different sequence; the sequence was close to that of the IA group, which caused outbreaks in Japan in 1990-1991.

In the previous outbreaks in 1990 and 1991, the infection was clustered in January - April. In 1999, however, infection was distributed evenly throughout the year. In 1990-1991, infected oysters or clams were the most likely major sources of infection, whereas in 1999, infections contracted via sexual and other routes were observed. A similar situation has been reported (4).

REFERENCES

  1. Frosner, G.G., Overby, L.R., Flehmig, B., Gerth, H.J., Haas, H., Decker, R.H., Ling, C.M., Zuckerman, A.J. and Frosner, H.R. (1977): Seroepidemiological investigation of patients and family contacts in an epidemic of hepatitis A. J. Med. Virol., 1, 163-173.
  2. Corey, L. and Holemes, K.K. (1980): Sexual transmission of hepatitis A in homosexual men. N. Engl. J. Med., 302, 435-438.
  3. Mitchell, J.R., Presnell, M.W., Atkin, E.W., Cummins, J.M. and Liu, O.C. (1966): Accumulation and elimination of poliovirus by the Eastern oyster. Am. J. Epidemiol., 84, 40-50.
  4. Gust, I.D. and Feinstone, S.M.(1988): Epidemiology. p 163-192. In Boca Raton, F.F. (ed.), Hepatitis A. CRC Press, Inc., Boca Raton, Fla., USA.


*Corresponding author: E-mail: shayashi@imcj.hosp.go.jp


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