A combination of historical and genetic research reveals the error and hype that led to the coining of the term 'Patient Zero' and the blaming of one man for the spread of HIV across North America.
A new study proves that a flight attendant who became notorious as the human epicentre of the US AIDS crisis of the 1980s - and the first person to be labeled the 'Patient Zero' of any epidemic - was simply one of many thousands infected in the years before HIV was recognized. Research by a historian from the University of Cambridge and the genetic testing of decades-old blood samples by a team of US scientists has demonstrated that Gaétan Dugas, a French-Canadian gay man posthumously blamed by the media for spreading HIV across North America, was not the epidemic's 'Patient Zero'.
In fact, work by Dr Richard McKay, a Wellcome Trust Research Fellow from Cambridge's Department of History and Philosophy of Science, reveals how the very term 'Patient Zero' - still used today in press coverage of outbreaks from Ebola to swine flu to describe the first known case - was created inadvertently in the earliest years of investigating AIDS.
Before he died, Dugas provided investigators with a significant amount of personal information to assist with studies into whether AIDS was caused by a sexually transmitted agent. McKay's research suggests that this, combined with confusion between a letter and a number, contributed to the invention of 'Patient Zero' and the global defamation of Dugas.
Dr McKay's work has added important contextual information to the latest study, led by Dr Michael Worobey from the University of Arizona and published in the journal Nature, which has compared a new analysis of Dugas's blood with eight other archived serum samples dating back to the late 1970s.
"Gaétan Dugas is one of the most demonised patients in history, and one of a long line of individuals and groups vilified in the belief that they somehow fuelled epidemics with malicious intent," says McKay.
While his wider research traces this impulse to blame back several centuries, for the Nature paper McKay located the immediate roots of the term "Patient Zero" in an early 'cluster study' of US AIDS patients.
Mistaken for zero
Reports emerged in early 1982 of historical sexual links between several gay men with AIDS in Los Angeles, and investigators from the Centers for Disease Control (CDC) undertook a study to interview these men for the names of their sexual contacts.
They uncovered more links across southern California, but one connection was named several times despite not residing in the state: Case 057, a widely travelled airline employee. Investigators found that his sexual contacts included men in New York City, and some of his sexual partners developed symptoms of AIDS after he did.
CDC investigators employed a coding system to identify the study's patients, numbering each city's cases linked to the cluster in the sequence their symptoms appeared (LA 1, LA 2, NY 1, NY 2, etc.). However, within the CDC, Case 057 became known as 'Out(side)-of-California' - his new nickname abbreviated with the letter 'O.'
Because other cases were numbered, it was here that the accidental coining of a new term took place. "Some researchers discussing the investigation began interpreting the ambiguous oval as a digit, and referring to Patient O as Patient 0," says McKay. "'Zero' is a capacious word. It can mean nothing. But it can also mean the absolute beginning."
The LA study expanded, due in no small part to information provided by Case 057. Over 65% of men in the cluster reported more than 1,000 partners in their lifetimes, over 75% more than 50 in the past year. But most could offer only a handful of names of those partners.
As well as donating plasma for analysis, Case 057 managed to provide 72 names of the roughly 750 partners he'd had in the previous three years. Also, his distinctive name may have been easier for other men to remember, says McKay. "The fact that Dugas provided the most names, and had a more memorable name himself, likely contributed to his perceived centrality in this sexual network."
By the time the expanded study was published in 1984, the same year Dugas died of his illness, the cluster showed dozens of cases connecting several North American cities. Near the very centre of an accompanying diagram is a floating case that links both coasts, the itinerant Dugas. Case 057, the 'Out-of-California' case, had been rechristened simply as "Patient 0" - causing much speculation in the media.
'Casting' an epidemic
The journalist Randy Shilts would use the LA cluster study as an important thread in his bestselling book on the AIDS crisis, And the Band Played On. During the book's research, he became fascinated by the study's 'Patient 0'.
Motivated to find out more about this man, Shilts eventually learned his name in 1986. The journalist tracked down his friends and colleagues for interviews, and, as "Patient Zero," made him one of the more memorable villains in his book.
To call attention to the crisis, Shilts set out to "humanise the disease", says McKay, who discovered that an early outline for the book actually listed 'The Epidemic' itself among the cast of characters. "To Shilts, Dugas as Patient Zero came to represent the disease itself."
The 1982 study had initially suggested to investigators that the period between infection and the appearance of AIDS symptoms might be several months. By the time Shilts's book was published in 1987, however, it was known that an infected individual might not display symptoms for several years, and that the study was unlikely to have revealed a network of infection. Yet Shilts uncritically resurrected the story of the Los Angeles cluster study and its 'Patient 0,' with long-standing consequences.
The journalist's decision provoked immediate criticism from AIDS activists in lesbian and gay communities across North America and the UK. Some of their works of protest are cited in the Nature study, and explored in greater detail in McKay's own forthcoming book and in a 2014 article he published in the Bulletin of the History of Medicine.
"In many ways, the historical evidence has been pointing to the fallacy of Patient Zero for decades," explains McKay. "We now have additional phylogenetic evidence that helps to consolidate this position."
McKay describes the very phrase 'Patient Zero' as "infectious." "Long before the AIDS epidemic there was interest in locating the earliest known cases of disease outbreaks. Yet the phrases 'first case,' 'primary case,' and 'index case' didn't carry the same punch.
"With the CDC's accidental coining of this term, and Shilts's well-honed storytelling instincts, you can see the consolidation of an 'infectious' formula that would become central to the way many would make sense of later epidemics."
Now, almost 30 years since Shilts's book, analysis of the HIV-1 genome taken from Dugas's 1983 blood sample, contextualised through McKay's historical research, has shown that he was not even a base case for HIV strains at the time, and that a trail of error and hype led to his condemnation as the so-called Patient Zero.
The researchers say it may be naïve to expect Patient Zero's legendary status, or the popular impulse to attribute blame for disease outbreaks, to ever disappear.
"Blaming 'others' - whether the foreign, the poor, or the wicked - has often served to establish a notional safe distance between the majority and groups or individuals identified as threats," says McKay.
"In many ways, the US AIDS crisis was no different - as the vilification of Patient Zero shows. It is important to remember that, in the 1970s, as now, the epidemic was driven by individuals going about their lives unaware they were contracting, and sometimes transmitting, a deadly infection.
"We hope this research will give researchers, journalists and the public pause before using the term Patient Zero. The phrase carries many meanings and a freighted history, and has seldom pointed to what its users have intended."