Its expansion was frighteningly fast. A handful of AIDS cases were first recognized in the U.S. at the beginning of the 1980s. But AIDS was soon seen around the world.
By 1990, the world had a pandemic on its hands. In 1997, the peak of the epidemic, more than 3 million people became newly infected with HIV.
Then science struck back. Drugs approved for HIV treatment in the mid-1990s proved profoundly effective, transforming AIDS from a death sentence to a chronic illness. Those treatments, combined with an international commitment to manage the disease by providing access to free drug therapy, led to a steep drop in new HIV infections.
The United Nations has kept track of HIV worldwide for the past couple of decades. Below, we use that data to explore some of the trends in HIV prevalence. (The chart shows the percentage of the population, ages 15 to 49, living with HIV.)