The first AIDS cases were reported by the CDC in 1981

The first official report of the disease later named AIDS was published by the CDC on June 5, 1981, in its Morbidity and Mortality Weekly Report. It described five previously healthy young gay men in Los Angeles with Pneumocystis carinii pneumonia, a lung infection seen almost only in people with badly damaged immune systems. Two had already died.

The item, titled “Pneumocystis Pneumonia — Los Angeles,” came from Los Angeles clinicians led by UCLA immunologist Michael Gottlieb. The men, aged 29 to 36, also carried cytomegalovirus and candida infections. The authors could not name a cause, but their editorial note pointed in the right direction:

“All the above observations suggest the possibility of a cellular-immune dysfunction related to a common exposure that predisposes individuals to opportunistic infections such as pneumocystosis and candidiasis.” — MMWR, June 5, 1981

First report, not first cases

The bulletin recorded the epidemic; it did not start it. Molecular-clock estimates place the pandemic strain’s common ancestor near the start of the 20th century, and the virus stayed well ahead of the paperwork:

• 1959 and 1960: a blood sample and a lymph-node biopsy from Kinshasa, analysed genetically, show HIV-1 was already diversifying in west-central Africa.
• October 1980 to May 1981: the five Los Angeles men were treated at three hospitals.
• June 8, 1981: the CDC set up a task force.
• December 1981: 337 cases of severe immune deficiency had been reported, while the CDC estimates roughly 42,000 Americans were already unknowingly infected.
• The following year: the syndrome was formally named AIDS; its virus was identified in the years after.
• 1996: when MMWR reprinted the report, AIDS had been diagnosed in 548,000 Americans and 343,000 had died.