patient zero

The term patient zero is an epidemiological term for the person who transmits an infection into a population that had been free of it. The OED records the first published use of the term being in Randy Shilts’s 1987 And the Band Played On, a book about the early years of the AIDS pandemic. Shilts identified a French-Canadian flight attendant by the name of Gaëtan Dugas as patient zero, the man who introduced AIDS into North America. But, it turns out, Shilts was dead wrong. Not only was Dugas unfairly blamed for being the source of the disease, the term itself arose out of a misinterpretation of nomenclature used by the Centers for Disease Control (CDC).

Dugas was the fifty-seventh case of the disease that would eventually come to be known as AIDS that came to the attention of the CDC. As such, he was initially called Case 57 or Patient 57. The CDC used a separate labeling system when it examined specific clusters, and one such study of a cluster of gay men in Los Angeles labeled the cases as LA # (e.g., the cluster’s LA 6 was the CDC’s Case 032). When Dugas was linked to this cluster, he became Patient O (that’s a capital letter O, not a zero), with the O standing for outside-of-California. Since Dugas was one of the few cases, if not the only case, labeled with a letter, as opposed to a number, the CDC researchers quickly took to calling him patient zero. (It is likely that internal documentation at the CDC used the term prior to the published use in Shilts’s book, but no one has produced such documentation to date.) This shift had the unfortunate result of making it seem as if Dugas was the source of the disease in this cluster, because zero precedes one and because of an association with the nuclear targeting term ground zero.

Dugas was also depicted in Shilts’s book and in the popular imagination as something of a monster. According to this image, not only was he extraordinarily promiscuous, but he also deliberately infected others after he knew he had the disease. There is no evidence to support either of these ideas. The number of Dugas’s sexual partners was similar to that of others in the cluster, and he was quite cooperative with the CDC investigators, even flying to Atlanta to assist in the epidemiological study. Ironically, it was Dugas’s cooperative attitude and ability to recall the names of his many sexual partners that both made him especially valuable to the investigators and led to the impression that he was a particularly effective vector of the disease. Dugas died of AIDS in 1984.

So if Dugas was not the source of the disease, where did it come from? A study published in Nature in November 2016 of genetic evidence of HIV strains shows that the disease migrated from Africa to Haiti in the 1960s, and from Haiti to New York City by the early 1970s. But trying to pinpoint the exact source of the disease, while perhaps valuable from an epidemiological standpoint, is ethically questionable, running the risk of placing the blame on a person rather than the virus, as was done with Dugas.


Oxford English Dictionary, third edition, s. v. “patient zero, n.,” June 2005.

Worobey, Michael, et al. “1970s and ‘Patient 0’ HIV-1 Genomes Illuminate Early HIV/AIDS History in North America.” Nature, vol. 539, 3 November 2016, 98–101.

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