The Topic of This Month Vol.21 No.7(No.245)

HIV/AIDS has been under surveillance since 1984 and, from 1989 through March 31, 1999, the surveillance was operated in compliance with the AIDS Prevention Law (excluding the cases infected by use of coagulation-factor products). Since April 1, 1999, the trend of HIV/AIDS has been comprehended as one of the category IV notifiable infectious diseases based on the Law Concerning the Prevention of Infectious Diseases and Medical Care for Patients of Infections. All physicians must notify the nearby health centers within 7 days any diagnosis of AIDS patients and HIV-infected persons without AIDS (hereafter abbreviated to HIV cases). The health centers must further transfer the reports to the local governments (prefectures, and designated cities and special wards which have health centers) and to the National Infectious Disease Surveillance Center (in the National Institute of Infectious Diseases) through the computer network system. The reports must include the following information: sex and age, diagnostic procedures, clinical status, onset date, diagnosis date, AIDS-defining diseases, place of residence, suspected country/area and mode of infection. The following is based upon the data in the 1999 annual report confirmed by the National AIDS Surveillance Committee on April 21, 2000.

1. HIV/AIDS incidence in 1999

HIV cases and AIDS patients newly reported in 1999 totaled at 530 and 300, respectively. Cases infected by sexual contacts were predominant, accounting for 77% of HIV cases and 73% of AIDS patients. Japanese males predominated, accounting for 72% of HIV cases and 71% of AIDS patients (Fig. 1). The ratio of males to females was 4:1 in HIV cases and 6:1 in AIDS patients. A greater part of the cases were infected inside Japan (79% of HIV cases and 69% of AIDS patients) (Fig. 2). Most reports came from Tokyo Metropolis and the neighboring prefectures (76% of HIV cases and 71% of AIDS patients), followed by Kinki district (11% of both HIV cases and AIDS patients).

2. Comparison with the 1998 reports

The number of HIV cases reported in 1999 was larger by 108 than the preceding year (about 26% increase), the largest number of annual reports ever since the under surveillance of HIV/AIDS. As in 1998, domestic infection of Japanese males prevailed and infection due to either homosexual contacts or heterosexual contacts increased. An increase in number of reports from Tokyo Metropolis and Kyushu districts was conspicuous. The reported AIDS patients increased by 69 from the preceding year (about 30% increase), which was largely due to heterosexual contacts of both Japanese and non-Japanese patients. Since the law controlling the surveillance has been replaced, a direct effect on the number of reports might have occurred. It seems necessary to take the modified system into account in concluding comparison between 1998 and 1999.

3. The trend of incidence from January 1985 through December 1999

The cumulative reports of HIV cases and AIDS patients until December 31, 1999 counted at 3,443 and 1,586, respectively. The following is a summary of the incidence excluding those infected by the use of coagulation-factor products. (An independent HIV/AIDS study group organized by the Ministry of Health and Welfare confirmed additional 1,434 HIV cases and 631 AIDS patients due to HIV-contaminated products of coagulation factor as of the end of October 1997).

1) The annual reports of HIV cases decreased after the 1992's peak but since 1995 have had the tendency to increase continuously (Fig. 3a). The increased HIV cases are ascribable to the domestic infection increase in Japanese males; Japanese female cases have a tendency to increase slowly. Non-Japanese cases of both sexes have been kept on the same level or rather tended to decrease for the past 6 years. The ratio of non-Japanese cases was about 20% in 1999, showing a gradual decrease during the past 6 years.

As for the mode of infection, sexual contact is the most common (heterosexual contacts 47% and homosexual ones 26%), whereas HIV cases due to intravenous drug use or mother-to-child infection were rather rare, each being 0.6% (Fig. 4). Although cases due to heterosexual contacts, homosexual contacts and unknown risk factors have each continuously been increasing among Japanese, those among non-Japanese have been decreasing or kept the same level (Fig .5). Infection by homosexual contacts increased largely among Japanese in 1999, surpassing that by heterosexual contacts. Those of unknown mode of infection have accounted for about 40% of the non-Japanese cases yearly and also about 15% of the Japanese cases.

Peaks in age distribution of HIV cases are seen at 25-34 years of age in males and 20-29 years in females irrespective of the nationality. It is notable that domestic infection and unknown place of infection have been increasing among Japanese males and that infection within Japan is increasing among non-Japanese males. Non-Japanese cases are most predominantly visitors from Southeast Asia, followed by those from Latin America and sub-Saharan Africa.

2) Reports of AIDS patients kept on increasing until 1997 and showed the tendency of decrease for the first time in 1998, but increased again in 1999 (Fig. 3b). AIDS patients markedly increased among Japanese males; the increase in both sexes of non-Japanese and Japanese females was slight. The ratio of non-Japanese patients has been on the same level 25-30% during the past 6 years (about 25% in 1999).

Of the mode of infection, sexual contacts were most predominant in AIDS patients as in HIV cases (heterosexual contacts 46% and homosexual ones 23%); intravenous drug use and mother-to-child infection were rather rare, being 0.9 and 0.8%, respectively. Among Japanese patients, reports of infection by heterosexual contacts showed increase and those by homosexual contacts and those of unknown mode of infection showed repeated increase and decrease during the past 6 years. The ratio of cases of unknown mode of infection was over 45% in non-Japanese and over 25% in Japanese patients.

The maximum age distribution is situated at 40-49 years of age among Japanese male patients; that is situated at 25-34 years among Japanese female and non-Japanese patients. Domestic infection is increasing among Japanese males.

If examined the distribution of AIDS-defining diseases with cumulative reports of Japanese and non-Japanese AIDS patients (1,149 and 437, respectively) as the denominator, the two groups will show similar distributions. Pneumocystis carinii pneumonia was most common accounting for 46 and 40%, respectively, followed by candidiasis (21 and 14%, respectively) and wasting syndrome due to HIV (12 and 13%, respectively). A significant difference in active tuberculosis cases was seen between the two groups; 7.0% of Japanese patients, while 14% of non-Japanese patients.

3) HIV-antibody-positive rate of blood donors has increased yearly, attaining the highest rate ever reported in 1999, being 1.02 positives per 100,000 donations (Fig. 6 and see p. 125, IASR, Vol. 21, No. 6). Besides, cases of HIV testing and counseling at health centers markedly decreased in 1999 from the preceding year to 48,218 (53,218 cases in 1998) and 103,206 (111,046 cases in 1998), respectively. It is requisite to carry out HIV testing and counseling at places and time convenient for many people and to enlighten on and propagate activities pleading more positive AIDS prevention.

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