Epidemiological characteristics on human immunodeficiency virus infection and acquired immunodeficiency syndrome in Japan.

The first case of human immunodeficiency virus (HIV) infection/acquired immunodeficiency syndrome (AIDS) in Japan was diagnosed in a homosexual male in 1985. The Ministry of Health and Welfare formed the AIDS Surveillance Committee, which published HIV seropositive and AIDS data at 2-month intervals. Excluding persons infected through blood products there were 971 HIV seropositives by April 1993, and 204 reported cases of AIDS. One of the epidemiological characteristics of HIV infection and AIDS in Japan is the rapid increase of cases of transmission through heterosexual contact since 1991. Before this, homosexual transmission was the commonest reported mode of transmission. Sporadic cases of mother-to-child transmission and some cases due to injecting drug use were also reported. It is predicted that heterosexual contact will be the primary mode of transmission of HIV in the future. Virtually all the diagnosed AIDS cases so far have been reported to this surveillance network, and it will be an important task of the network to monitor the HIV seropositive cases.