The Topic of This Month Vol.19 No.4(No.218)

AIDS/HIV Surveillance in Japan, 1985-1997

The National AIDS/HIV Surveillance in Japan was started in 1984. The Acquired Immunodeficiency Syndrome (AIDS) Prevention Law was put in effect in 1989, when it was started to examine and analyze every case of infection from coagulation factor products by a different study group. All HIV-infected persons and AIDS patients except those infected by use of coagulation factor products are reported to the National AIDS Surveillance Committee, chaired by Dr. Shudo Yamazaki, the Director General, the National Institute of Infectious Diseases.

Physicians who diagnosed HIV-infected persons without AIDS (hereafter abbreviated to HIV cases) or AIDS patients have an obligation to submit the filled-in AIDS/HIV-infected case report (Form 1) to the AIDS and Specific Diseases Control Division, the Health Service Bureau, the Ministry of Health and Welfare through the prefecture or designated city within seven days after diagnosis. The items of the report to be filled in by the physicians are laboratory diagnosis of HIV infection (the confirmatory test is a must), main symptoms, sex, age, nationality, place of residence (prefecture or designated city's name), route of infection, place of infection, date of diagnosis, and date of reporting.

If any change occurs in the conditions of an HIV case or AIDS patient on which the initial report has been submitted (HIV case-->AIDS patient or AIDS patient-->death), the clinical-status-change report (Form 2) will be collected through the same route.

At the end of 1997, the National AIDS Surveillance Committee re-examined analyses of all data collected during the period from 1985 to the end of 1997 and compiled the results into a report. The summaries of the report are given under 1 and 2 below:

1. AIDS/HIV in 1997: In 1997, 397 HIV cases and 250 AIDS patients were reported. Both outnumbered those in the preceding year (375 and 235 cases, respectively). The annual reports of AIDS patients were the largest in number after the surveillance was started.
(1) Concerning the mode of infection, sexual contacts (77% of HIV cases and 64% of AIDS patients) and concerning the nationality and sex, Japanese males (59% of HIV cases and 68% of AIDS patients) were in the majorities. As for the place of acquiring HIV infection, the greater parts of Japanese cases were infected inside Japan (75% of HIV cases and 61% of AIDS patients).
(2) The male-to-female ratio of HIV cases was 2.5 (283:114) and that of AIDS patients 5.1 (209:41) in 1997.
(3) The largest numbers of reports of AIDS/HIV cases came from Tokyo. Of all the reports in 1997, 76% of those of HIV cases and 75% of those of AIDS patients came from Tokyo and the neighboring prefectures. Patients infected through homosexual contact were particularly concentrated in Tokyo.
(4) Japanese males infected with HIV through heterosexual contact formed a peak at the age group of 45-49 years, those through homosexual contacts at the group of 25-29 years, and female cases through heterosexual contact at the group of 20-24 years.
(5) After the start of HIV-antibody screening (November 1986), no case of infection due to blood transfusion had been found until 1997, when a case infected by use of domestically donated blood was reported for the first time. This was due to the blood collected from an infected person before antibody production (during the window period).

2. The summary of AIDS/HIV during the period from 1985 to the end of 1997: The cumulative numbers of reports during the 13 years reached 2,490 of HIV cases (Table 1) and 1,056 of AIDS patients involving 528 deaths (Table 2). (In addition, hemophiliacs infected through use of HIV-contaminated coagulation-factor products before heat-treated products were introduced numbered 1,495 HIV cases accounting for 38% of total HIV cases and 628 AIDS patients involving 485 deaths accounting for 37% of all AIDS patients.)
(1) Of the modes of infection, HIV cases (Table 1) infected by heterosexual contact accounted for 49%, homosexual contact 23%, intravenous drug abuse 0.6%, mother-to-child infection 0.8%, other modes 2.0%, and unknown modes 25%. The ratios of different modes of infection of AIDS (Table 2) are very similar to those of HIV cases.
(2) The trend of annual reports of HIV cases and AIDS patients is shown in Fig. 1. In Japan, unlike in most European countries and USA, the tendency of expanding the infection is being kept on. The nationalities of HIV cases comprised Japanese males 43%, Japanese females 9.0%, non-Japanese males 14% and non-Japanese females 34%. Those of AIDS patients comprised 66%, 6.0%, 20% and 8.0%, respectively. The annual trends of nationalities and of sexes of the patients are shown in Figs. 1a (HIV cases) and 1b (AIDS patients). The peak of HIV cases seen in 1992 was due to non-Japanese females, mainly young women from Southeast Asia.
(3) Japanese cases infected through either heterosexual or homosexual contract has been increasing since 1991. As for the places of infection, it is noticeable that domestic infection of Japanese males has been increasing since 1992 (Fig. 2).
(4) All donated blood is screened for HIV antibody at the Japanese Red Cross Blood Center; blood donors showing positive HIV antibody in the confirmatory test has steadily been increasing in number since 1990. In 1997, of about six million blood donations, 54 (including five from females) were found HIV-antibody positive, corresponding to 0.9 per 100,000 donations (Fig. 3).

3. HIV-1 subtypes prevailing in Japan: B subtype was detected from most patients infected through blood products and Japanese males infected through heterosexual contacts before 1993. Since 1994, E subtype (Thai EA) has exclusively been detected, indicating that HIV infection through heterosexual contact has recently been caused mainly by E subtype in Japan (see p. 74 of this issue).

Summary: Being different from USA and most European countries, where HIV infection has reached a peak, HIV-infected persons are still increasing in number in Japan. It is an urgent task to take effective preventive measures based on due considerations of the fact that the domestic infection of Japanese males through sexual contact is increasing and the HIV-positive rate of blood donors tends to increase.

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