The First AIDS Cases Are Reported and a New Pandemic Begins
Five unexplained pneumonia cases in Los Angeles gay men mark the first published record of what would become a virus that has killed over 44 million people
Quick facts
- First report
- CDC Morbidity and Mortality Weekly Report, June 5, 1981
- Initial cases
- Five young gay men, Los Angeles, October 1980-May 1981
- Pathogen
- HIV (human immunodeficiency virus), identified later; origin traced to chimpanzees
- Cumulative global toll by 2024
- An estimated 44.1 million deaths
- Living with HIV, 2024
- About 40.8 million people worldwide
What happened
On June 5, 1981, the CDC's Morbidity and Mortality Weekly Report published a short article titled "Pneumocystis Pneumonia, Los Angeles," describing five previously healthy young gay men treated at three Los Angeles hospitals between October 1980 and May 1981 for Pneumocystis carinii pneumonia, a form of lung infection almost never seen outside people with severely compromised immune systems. Two of the five had already died by the time of publication, and the remaining three died soon after. Michael Gottlieb, the immunologist who first noticed the pattern, worked with CDC officials to rush the report into print because case numbers were rising too fast for a standard scientific paper. Similar clusters of rare infections and cancers were soon reported from other cities, and the CDC formed a task force just three days after publication. HIV, the virus responsible, is now understood to have jumped from chimpanzees to humans earlier in the 20th century, decades before it was recognized.
Why it matters
This report marks the first official documentation of what would become the HIV/AIDS pandemic, which by 2024 had killed an estimated 44.1 million people worldwide and left 40.8 million people living with the virus. Unlike the acute epidemics elsewhere on this timeline, HIV causes a slow, years-long illness before symptoms appear, which delayed recognition of its scale and, combined with the stigma attached to the communities first affected, slowed the public health response for years.
How we know
The original MMWR report is a primary CDC document; the U.S. National Library of Medicine's historical account, drawing on the same report and interviews with participants including Gottlieb, describes how the report came together under time pressure as case counts climbed.
Sources
- U.S. National Library of Medicine, Circulating Now. June 5, 1981, The First Report of AIDS in the U.S. · Primary source (author-declared)circulatingnow.nlm.nih.gov · Cited as a "primary" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
- World Health Organization. HIV and AIDS · Reputable sourcewho.int · The domain "who.int" is on our Reputable source registry.
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