In epidemiology, the term patient zero is used to refer to the first documented case in a chain of transmission of a disease. In many outbreaks, knowing who the patient zero is helps researchers reconstruct the route of infection and contain the spread.
However, it’s important to note that patient zero is not necessarily the first human to contract the disease. It may simply be the first to attract the attention of researchers or the first case traced in a network of contacts.
The figure of patient zero appears as the beginning of everything, as the first infected person or the origin of the outbreak. But, who was really the most famous patient zero in the world? Let’s see how this concept, which mixes science, myth, and misunderstandings, came about.
The story takes us to a well-known crisis, that of HIV/AIDS in the 80s, where a man was unfairly singled out as the origin of one of the deadliest pandemics of the 20th century. He was Gaëtan Dugas, a flight attendant who for a long time was known as patient zero of AIDS in North America.
Gaëtan Dugas and the Origin of the Myth
Gaëtan Dugas was a flight attendant for Air Canada, diagnosed with HIV in the early 1980s. He was 31 years old when he died in 1984, but his story would be revived years later, in 1987, when journalist Randy Shilts published the book
And the Band Played On. In this influential text about the beginnings of the AIDS epidemic in the United States, Shilts pointed to Dugas as patient zero, a man who, according to the book, had been warned of his diagnosis and, even so, would have continued to have unprotected sex with multiple partners.
The story was widely covered by the media. Dugas was portrayed as a kind of “viral villain,” someone who deliberately spread the disease. His public image was tarnished, and the myth of patient zero as the culprit of the epidemic was consolidated.
However, there was a problem: the story wasn’t entirely true.
The Error of the Letter “O”
Dugas’ identification as patient zero stems, in part, from a misinterpretation. During an epidemiological study by the Centers for Disease Control and Prevention in the 80s, HIV cases were labeled in a network of sexual contacts. Dugas was assigned the code
“Patient O”, the letter “O” from
“Outside California”, to indicate that he did not live in the state.
But when this data reached the public and some journalists, the “O” was misinterpreted as a zero, becoming
“Patient 0” or “patient zero.” From there, the story took a sensationalist turn.
Dugas, in fact, actively collaborated with epidemiologists, providing a list of his sexual partners and helping scientists map how the virus was spreading. So more than a villain, he was an ally in the investigation.
Decades later, advances in viral genetics allowed for a more precise reconstruction of the origin of HIV. In 2016, a study led by Michael Worobey’s team from the University of Arizona analyzed old blood samples from patients diagnosed in the 1970s. By studying the virus’s genome, the researchers demonstrated that HIV was already circulating in the United States long before Dugas appeared on the scene.
The analysis placed the introduction of the virus in North America around 1970, possibly through the Caribbean. Dugas was only one of many infected in the early years of the epidemic, and clearly was not the first. The study concluded that “the virus was already here before he arrived”.
The Weight of Stigma
The story of the false patient zero is a clear example of the harm that stigma can cause in the context of infectious diseases. Instead of promoting scientific understanding, sensationalism led to the demonization of a person and fueled fear, homophobia, and misinformation surrounding the disease.
During the first years of the epidemic, many sick people were marginalized, and Dugas’s case reinforced the misconception that AIDS was a “fault” or a “consequence” of certain lifestyles. This narrative hindered the medical response, delayed social empathy, and made access to treatments difficult.
Should we still use the term patient zero?
Nowadays, many experts suggest avoiding the term “patient zero,” as it can create a false impression of causality and hold individuals accountable. Instead of seeking blame, current public health focuses on understanding transmission patterns, strengthening detection systems, and thus avoiding stigma.
Through the history of Dugas, a lesson is learned: viruses do not discriminate, but we can, for better or for worse.
