1984: There are 4,177 reported AIDS cases in the United States, with 1,600 of these in New York City. Homosexuals, Haitians, hemophiliacs, and intravenous drug users are the populations at highest risk for contracting AIDS.

Today: AIDS is on the decline in New York City. There are more than thirty million people infected with AIDS worldwide, the majority of them in sub-Saharan Africa. Heterosexual sex is the main method of transmission in the United States and worldwide

1984: There is no effective treatment against AIDS until 1985, when the Federal Drug Administration (FDA) approves a drug called AZT.

Today: AZT is still used to fight AIDS. When combined with a class of drugs called protease inhibitors, it is effective in delaying the onset of full-blown AIDS among people infected with HIV. The treatment entails taking costly and carefully timed "cocktails" of different drugs. The treatment dramatically increases the life...