The story of how “Patient Zero” and AIDS arrived in New York in 1979 and triggered the epidemic in North America has been told so many times in so many different ways that for many people it's become an accepted truth of our modern history.
It's a compelling narrative, but it's not quite right.
In a study published Wednesday in the journal Nature, researchers used genomic sequencing of blood samples from that era to go back in time and reconstruct the “family tree” of the virus in unprecedented detail. The findings are stunning, debunking many popular beliefs about the virus's origins and spread and filling in holes about how it made its way to the United States.
The work, led by Michael Worobey from the University of Arizona and Richard McKay from the University of Cambridge, confirms the controversial theory that the virus crossed over from the Caribbean (rather than going from the United States to the Caribbean, as some have argued). The researchers also found that the location of the initial outbreak was New York City, not San Francisco. And they pinpointed that the AIDS virus appeared to have been circulating in U.S. borders for much longer than was previously known, and made the jump in or around 1970 — about a decade before it was officially recognized to be in the United States in 1981.
The map below shows the main patterns of how HIV-1 subtype B — the main subtype found in that time in men who have sex with men and that marked a turning point in the pandemic — spread from Africa to the Haiti and then to New York, and from New York to many other parts of the country. The years on the map correspond with the estimated date that the virus arrived in a location.
“Geographically there is an unmistakable signal that this lineage did diversify in the Caribbean before it moved into the U.S.,” Worobey said Tuesday in a conference call with journalists. However, he added, how the virus got to the United States remains an open question.
“It could have been a person of any nationality. It could have even been blood products. A lot of blood products used in the United States in the 1970s actually came from Haiti,” he explained.
The analysis involved looking at archived serum samples, many nearly 40 years old, from studies that were discontinued long ago. One involved men who have sex with men in New York and San Francisco and two were of men at risk of contracting hepatitis B. A significant percentage of the samples — from 3.7 to 6.6 percent depending on the study — showed HIV antibodies, and the researchers randomly selected 20 to attempt to sequence. Unfortunately, many were degraded because they had been in long-term storage, so researchers spent years trying a number of new techniques to reconstruct and “amplify” the viral fragments. Finally, using a technique the researchers described as borrowing from the one scientists use to look at DNA from Neanderthals and other ancient creatures that no longer roam the earth, they were able to complete the sequences for eight.
These were of five patients from New York and three from San Francisco in 1978 to 1979, which are among the oldest viral HIV samples ever recovered in the world.
Researchers separately sequenced the virus found in Patient Zero and found that his HIV-1 genome appeared “typical” of U.S. strains of the time and that there was extensive genetic diversity around the time he appears to have been infected, indicating that the virus had probably been in the country and evolving several years earlier.
“He was evidently just one of many thousands infected prior to the recognition of HIV/AIDS,” they wrote in a supplementary discussion also published by Nature.
They explained that public health investigators at the time had dubbed him “Patient ‘O’” meaning the letter O and not the number zero because he came from ‘Out(side)-of-California,’" but that the letter became confused with the number in the medical literature and popular media and over time became part of the mythology of AIDS despite numerous attempts by some scientists to clarify his role in the epidemic.
Worobey, whose expertise is in virus evolution, and McKay, a science historian, wrote that their work shows there is “neither biological nor historical evidence for the widely held belief that he was the primary cause of the HIV epidemic in North America”
“This individual was simply one of thousands infected before HIV/AIDS was recognized,” McKay said.
The two spoke of the danger of the public's instinct to want to assign blame in infectious disease outbreaks, and noted that, in the case of the United States, the instinct has often been to look to foreigners as the cause. This dates back to Irish-born Mary Mallon, who was accused of spreading typhoid fever when she continued to work as a cook after she was identified as a healthy carrier.
In the early days of the AIDS epidemic, it wasn't just Canadian-born Dugas — written about in stories with headlines, such as “The man who gave us AIDS" -- who was vilified. In 1989, the CDC listed people from Haiti as being among the four “high-risk” groups for HIV, along with gays, heroin users and hemophiliacs — a designation that sparked some horrible discrimination that involved denying people from the country or even denying their children and grandchildren employment, housing and schooling.
“One of the dangers of focusing on a single Patient Zero when discussing the early phases of an epidemic is that we risk obscuring important structural factors that might contribute to its development — poverty, legal and cultural inequalities, barriers to health care and education. These important determinants risk being overlooked if we focus too readily on a Patient Zero,” McKay said.
Worobey added that an important distinction to make is that their work tracing the origins of the AIDS is not the same as placing blame on any individual or group.
“The pandemic virus ultimately comes from nonhuman primates, probably circulating in sub-Saharan Africa for probably 100 years at this time point today,” Worobey said.” The lineage of the virus we're talking about in this paper, so-called subtype B of HIV-1 group M, is just one of many branches on that evolutionary tree.”
“No one,” he emphasized, “should be blamed for the spread of a virus no one even knew about.”
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