In 1982, the Canadian air steward Gaétan Dugas wrote of his worsening illness in a letter to Ray Redford, his former lover. Believing he had what was being called “gay cancer”, Dugas had shaved his hair ahead of expected chemotherapy. He felt nude without it, he said. Like an alien.

Dugas told friends he was ready to fight and beat the cancer, but he died in 1984. By then, scientists and public-health officials had a new, more formal, name for the illness that claimed his life — HIV/AIDS. Dugas was given a different label, too. As the attention of politicians and journalists was drawn to the unfolding crisis, he was identified as ‘Patient Zero’ of the US epidemic. He was demonized as a knowing and callous reservoir of infection and as a deliberate transmitter of disease. He was regularly compared with Mary Mallon, better known as Typhoid Mary — the cook who, several decades earlier, ignored instructions not to prepare food, and infected dozens in New York City with that bacterial disease.

Thirty years on, samples of the virus that closed down Dugas’s immune system still exist. And in a research paper this week, disease scientists report how they have analysed its genetic sequence (M. Worobey et al. Nature http://dx.doi.org/10.1038/nature19827; 2016). The results are important for two reasons. In clinical terms, they show that Dugas’s virus was, in many ways, unexceptional. And in human terms, they clear his name.

Dugas was identified as Patient Zero in a 1987 book about the AIDS epidemic, And the Band Played On (St. Martin’s), by journalist Randy Shilts, who died in 1994. Shilts painted Dugas as a villain, and turned a typographical curiosity into a badge of dishonour. US scientists had spoken to Dugas as they investigated a cluster of cases of the new syndrome in Los Angeles in 1982. Because he didn’t live in the state, his case notes were marked as Patient O for “Outside of California”. When vocalized, the designation became muddled with the number zero. As Shilts said when he first heard the description: “Ooh, that’s catchy.”

The author introduced the air steward to the world as the original sinner. A man whose reckless behaviour and disregard for the health of his (many) sexual partners helped the AIDS epidemic to take hold. He became known as a lover driven by hate, and a foreigner who brought death and disease to US shores. The myth helped to drive the political response to the disease. It was used to demand laws to stop the deliberate transmission of the virus, and fuelled hostility towards a community that many believed had brought the disease on themselves as a perverse condemnation of their lifestyle.

Medical historians have chipped away at the pernicious story of Dugas as Patient Zero for years. They have pointed out, for example, how he helped epidemiologists to trace a significant number of his sexual partners. And how the scientific advice at the time was contradictory and distrusted by people whose sexuality medics had considered a psychiatric problem until just a decade earlier.

The latest genetic analysis completes the exoneration. The virus arrived in New York City from the Caribbean around 1970. There is nothing in the samples from Dugas that implicate him and his behaviour as key to its subsequent rapid spread. In his 1982 letter, Dugas wrote that “my mind is finding peace again”. RIP.