THE problem with providing a “rough, first-draft of history” is that so few people ever see the later drafts.
And so it goes with Gaétan Dugas, an Air Canada flight attendant who died in 1984 and soon thereafter was identified by the media as “Patient Zero” in the North American HIV/AIDS epidemic. Journalist Randy Shilts cast Dugas as such in his 1987 book, And the Band Played On; although other reports had avoided the mischaracterization, the moniker stuck.
Scientists have returned to this episode in a rigorous new Nature paper that traces the actual origin of the HIV/AIDS epidemic in the US back to the early 1970s.
About 35 million people have died from AIDS-related causes since the disease was discovered in the early 1980s. More than 36 million live with HIV infection today, 1.2 million of them in the US. Patients suffering from AIDS were first described in June 1981, in a Centers for Disease Control journal, and HIV was eventually demonstrated to be its cause by 1984.
Molecular sleuthing has pushed its probable origin in humans to 1908 or so, in what today is Kinshasa, the capital of the Democratic Republic of the Congo. Modern versions of the virus may have emerged as early as the 1920s, reaching the Caribbean in 1967, New York in 1971, and San Francisco in 1976.
“The NYC epidemic was already relatively mature and genetically diverse by 1979,” or three years before the first cluster of cases, in Los Angeles, were written up in a weekly journal of the CDC, the study notes.
Scientists relied on a bit of investigative luck and the relentless pounding of lab work. The authors, led by Michael Worobey of the University of Arizona, identified degraded HIV in samples from preserved Hepatitis B tests in 1978 and 1979. They restored the viral genetic material with excruciating precision, enabling them to set the US outbreak within the larger context of the virus’s evolutionary history.
Worobey, who has delivered talks on the results published on Wednesday last week, leads the field in unwinding the HIV’s “molecular clock.” The virus mutates at a steady rate as it reproduces, allowing researchers to estimate its evolutionary family tree based on changes observed in any particular strain. The disease probably jumped from chimpanzees to humans through hunting, as the animal blood mixed with that of hunters. A decade ago, the discovery of viral samples from 1960 allowed him to place its origin to about 1908.
The eight examples the scientists obtained might not sound like a lot. But it’s quite a haul, considering they had to screen more than 2,000 samples to find and restore them. When asked if there were a possibility of getting more than “only eight” examples, Worobey sounded a little sad.
“‘Only eight’ is like a dagger through my heart,” he said. Getting compatible results from that many samples would be a bit like drawing the ace of spades from a shuffled deck of cards eight times in a row. “It can’t be attributed to chance,” he said.
With their molecular evidence in hand, the scientists went back and studied the complete HIV genome of “Patient Zero,” who, it turns out, took on the title only by accident. Dugas, anonymously, was labeled “Patient O” in CDC investigators’ preliminary analysis, as in a patient “[O]utside of California.” That became “Patient 0” [zero] in the center of a cluster study of the outbreak. Why was he at the center of the outbreak? The authors suggest he was more forthcoming about his sexual partners — or in other words, the contagion map of which he became the center had a major sampling error.
“No one should be blamed for the spread of a virus that nobody even knew about,” said Richard McKay, a co-author and a University of Cambridge historian of medicine and public health.
In the CDC’s historical docket of the US outbreak, Dugas was Case 57. — Bloomberg
