Today marks 25 years since the first reports of a

mysterious disease that would later become known as AIDS surfaced in a Centers for Disease Control and Prevention report. The AIDS epidemic has spread to every corner of the world and infects 40 million people, according to the Joint United Nations Programmed on HIV/AIDS. The epidemic has been punctuated by misery and milestones, stigma and scientific breakthroughs.
1981: The first cases of unusual immune system failures are identified among gay men, some women and injection drug users.
1982: AIDS is defined and three modes of transmission established: blood, sexual intercourse and mother-to-child before or during birth.
1983 -- Scientists isolate the AIDS virus, and a year later identify it as HIV.
1985: A test for HIV, which has spread to every region of the world, becomes available. HIV screening of blood donations begins. Film star Rock Hudson discloses he has AIDS and dies.
1987: AIDS becomes the first disease debated on the floor of the U.N. General Assembly. AZT, the first therapy for AIDS, becomes available.
1988: Women account for half of adults living with AIDS in sub-Saharan Africa.
1990: Ronald Reagan apologizes for doing too little to combat AIDS while he was president. Indiana teenager Ryan White, a hemophiliac who put a face on AIDS discrimination, dies.
1991: Basketball giant Magic Johnson reveals he has HIV.
1993: AIDS becomes the leading cause of death among Americans ages 25-44.
1994: Scientists develop the first treatment to reduce mother-to-child transmission of HIV.
1996: A new class of AIDS drugs known as protease inhibitors begins to change AIDS from a death sentence into a chronic illness. Twenty-two million people are infected with HIV and the worldwide death toll reaches 6.5 million.
1997: The first human AIDS vaccine trial begins in the United States.
1998: Thirty-nine drug companies sue South Africa to prevent the entry of cheaper AIDS drugs. Blacks account for 49 percent of AIDS deaths in the United States, 10 times that of whites.
2000: The UNAIDS and the World Health Organization reach a deal with five drug companies to reduce the cost of HIV treatment in developing countries. Among gay men, blacks and Latinos now account for more U.S. AIDS cases than whites do.
2003: President Bush announces a $15 billion plan to fight AIDS in the developing world, where it is ravaging economies and lowering life expectancies.
2004: The first rapid test for HIV is approved.
SOURCES: UNAIDS, Centers for Disease Control and Prevention and Gay Men's Health Crisis