Well-Being Prevention & Cures

The search for Patient Zero of coronavirus — and why it’s so important

The panic around mitigating the spread of novel coronavirus globally is spurring medical experts to identify the origin of the outbreak. Specifically, they want to identify and locate Patient Zero. Technically referred to as an “index case,” Patient Zero is the first documented human infected by a disease of any outbreak.

The ability to find the origin case in an outbreak can help researchers determine when and how it started. This helps health experts model the progress of the disease — and take steps to prevent another outbreak from jumping from animals to humans.

Chinese authorities do not currently know who was the first human carrier of COVID-19. However, officials think the first case was contracted at a seafood and animal market in Wuhan, the capital of Central China’s Hubei province. 

In January, Chinese researchers published findings in The Lancet concluding that the first diagnosed patient was exposed on Dec. 1. The World Health Organization (WHO) hypothesizes that the outbreak started at the market and probably jumped from a living animal to a human carrier.

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Singling out one individual is not only extremely difficult, it also comes with serious considerations. Medical ethicists warn that it can stigmatize a patient.

Consider the story of Gaëtan Dugas, a gay flight attendant for Air Canada in the early 1970s. He was cast in many reports as Patient Zero of the HIV/AIDS epidemic and became a medical scapegoat in North America in the 1980s. Human error and alarmist reporting fueled the false narrative until Dugas was exonerated in 2016 — 32 years after his death.

Epidemiologists think differently about identifying the source. They are medical sleuths who believe that the more information they can discover about an outbreak, the greater potential to protect the public. 

Mary Mallon, better known as Typhoid Mary, is the most often-cited case. Born in Ireland in 1869, Mallon emigrated to the U.S. in 1884 where she began working for a variety of wealthy families as a domestic before she became a cook.

She was also a healthy carrier of Salmonella typhi — typhoid fever — meaning that she was infected with the pathogen but never showed any signs or symptoms herself. When a medical researcher discovered her condition, Mallon was placed in a three-year quarantine.

She was released in 1910 and was warned never to cook professionally again. Changing her name to Mary Brown, she shifted jobs regularly, which allowed her to thwart health officials for years. Ultimately, Mallon was discovered cooking at Sloane Hospital for Women, where she had infected 25 more people, two of whom died.

She spent the remaining 23 years of her life quarantined on an island in the East River in New York.

Different diseases and pathogens correspond to different levels of public outcry or intervention. 

“We do this via contact tracing which has a long history in public health and is not thought to be intrusive or coercive,” says Lawrence Gostin, a Georgetown University public health expert. 

“So from an ethics perspective, unless we used intrusive surveillance, like in China, it is warranted.” At this point, he says “it will be extraordinarily difficult to trace Patient Zero of coronavirus.

“Once the case goes back weeks, then it is perhaps impossible. We need to balance the value of knowing with the cost of trying to do it.”