1981: HIV/AIDS

AIDS was first observed in American gay communities but is believed to have developed from a chimpanzee virus from West Africa in the 1920s. It spreads through certain body fluids, moved to Haiti in the 1960s, and then New York and San Francisco in the 1970s.

Identified in 1981, AIDS destroys a person’s immune system, resulting in eventual death by diseases that the body would usually fight off. Those infected encounter fever, headache, and enlarged lymph nodes upon infection. When symptoms subside, carriers become infectious through blood and genital fluid, and the disease destroys t-cells.