June 1981 is the official birth date of the AIDS epidemic. In a short article published in the Centers for Disease Control’s Morbidity and Mortality Weekly Report (MMWR), American clinicians described a cluster of five cases of Pneumocystis carinii pneumonia, an infection of the lungs hitherto seen only in patients with severe impairment of their immune system. These five initial cases had been diagnosed in 1980–1 among gay men, all living in Los Angeles, who had been previously healthy and were not receiving drugs that suppressed the body’s immune response. At the time, the standard treatment for Pneumocystis pneumonia was an old drug called pentamidine, developed during WWII for the treatment of sleeping sickness, which happened to be highly active against Pneumocystis. Pentamidine was not commercially available and had to be distributed centrally from the CDC in Atlanta. An astute CDC technician found it strange to have received several requests for pentamidine within a short period of time from hospitals in California and, a bit later, from New York as well. This became the first step in the identification of the new syndrome by this federal agency.