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Gaétan Dugas, infamously, and wrongly, labeled Patient Zero. PHOTO: WIKIMEDIA COMMONS

‘Patient Zero’ no more

BOSTON–A   new study pinpoints with greater precision than ever before when and where HIV entered the United States and sparked North America’s AIDS epidemic. It also puts to rest a media-fueled theory about a peripatetic flight attendant with a very active sex life: so-called “Patient Zero,” who after his death became infamous for supposedly bringing the virus into the country and seeding the infection in different locales.

In And the Band Played On, the 1987 best-selling account of the U.S. epidemic’s early years, journalist Randy Shilts wrote in detail about Patient Zero, a Canadian named Gaétan Dugas who died from AIDS 3 years before the book was published. “[T]here’s no doubt that Gaëtan [sic] played a key role in spreading the new virus from one end of the United States to the other,” Shilts wrote. He did not say Dugas introduced the disease to North America, but subsequent media accounts, including one in Time magazine, did make that claim—and vilified Dugas. A front-page New York Post headline went so far as to proclaim, “THE MAN WHO GAVE US AIDS.” HIV/AIDS researchers have long been skeptical about the Patient Zero claim.

Last week at the Conference on Retroviruses and Opportunistic Infections here, Michael Worobey, an evolutionary biologist at the University of Arizona in Tucson, solidly debunked that claim, saying Dugas was far from what epidemiologists refer to as the “index patient” in the United States. Worobey’s new work will help put “the myth of Patient Zero” to rest, says epidemiologist Harold Jaffe of the Centers for Disease Control and Prevention (CDC) in Atlanta, who helped unravel the early spread of the disease.

The first AIDS cases surfaced in five gay men in Los Angeles, California, and were reported in CDC’s Morbidity and Mortality Weekly Report in June 1981. After HIV was proven to be the culprit in 1984, researchers analyzed stored blood samples from gay and bisexual men collected in the late 1970s in San Francisco, California, and New York City and found that the men already carried antibodies to the virus. Worobey plucked the virus from eight of those samples, which dated from 1978 and 1979, and obtained nearly the complete genetic sequences of each one. Jaffe, who had helped piece together Dugas’s connection to a cluster of early AIDS cases in California and New York, supplied a 1983 sample of the flight attendant’s blood, which also yielded a near-complete HIV genome.

HIV mutates at a constant rate each time it copies itself, so Worobey could use the differences among the sequences to create a family tree of the viruses and estimate when each isolate emerged. His work suggests the U.S. epidemic most likely began in New York City around 1970, when the real index case brought in a virus that closely matched the sequences of older HIVs isolated from people in Haiti and a few other Caribbean countries. Although his sample size is small, Worobey said the probability that New York City was the origin of the U.S. epidemic “is very, very high indeed.” He estimates the virus reached San Francisco around 1975.

On the family tree of the early U.S. isolates, Dugas’s HIV genome fell in about the middle. “There’s nothing special about his genome,” Worobey said. Although Dugas had been to Haiti—in 1977—there is no sign that he was either the index patient or key to spreading the virus around the country. Worobey notes that when CDC researchers were piecing together how the first AIDS cases were linked to each other, they originally referred to Dugas not by the number “0” but by the letter “O,” because he was from “outside” California. Later, for reasons that remain murky, Dugas morphed into Patient Zero.

So rather than Dugas sparking the U.S. epidemic, his case, historically speaking, really is just an “oh.”