From Nature:

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Participants in a 1983 Gay Pride parade in New York City protest against panic over AIDS.

In 1982, sociologist William Darrow and his colleagues at the US Centers for Disease Control and Prevention (CDC) travelled from Georgia to California to investigate an explosion in cases of Kaposi’s sarcoma, a type of skin cancer, among gay men. Darrow suspected that the cancer-causing agent — later shown to be a complication of HIV infection — was sexually transmitted, but lacked proof. His breakthrough came one day in April when three men from three different counties told Darrow that they had had sex with the same person: a French Canadian airline steward named Gaétan Dugas.

CDC researchers tracked down Dugas in New York City, where he was being treated for Kaposi’s sarcoma. With his cooperation, the scientists definitively linked HIV and sexual activity1. They referred to Dugas as ‘Patient Zero’ in their study, and because of a misunderstanding by journalists and the public, the flight attendant became known as the person who brought HIV to the United States. Dugas and his family were vilified for years2.

But an analysis of HIV using decades-old blood serum samples exonerates the French Canadian, who died in 1984. The paper3, published on 26 October in Nature, shows that the virus had been circulating in North America since at least 1970, and that the disease arrived on the continent through the Caribbean from Africa.

Richard McKay, a historian at the University of Cambridge, UK, and study co-author, says that scientists have always questioned the idea of a single Patient Zero, because some evidence suggested that the virus entered North America several times.

A team led by McKay and evolutionary biologist Michael Worobey at the University of Arizona in Tucson wanted a clearer picture of HIV’s …

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