Typhoid Mary

She might be the stuff of urban legend, but Typhoid Mary was a real woman. Mary Mallon emigrated from Ireland to New York City as a teenager and became an in-demand cook for the upper classes. But when a sanitary sleuth discovered that Mallon was the source of multiple typhoid outbreaks in the greater New York area, she ended up detained for decades on an island.

Today, Mallon has been reduced to a scary story, or a one-dimensional parable about the good of public health, but she wasn’t a simple villain or victim. And the challenges she and her captors faced—including misconceptions about the asymptomatic spread of disease and the precarious balance between individual liberty and public welfare—are ones we face today.

Wash your hands!

51: People Mary Mallon is thought to have infected

3: People infected by Mallon who died

26 years: Cumulative time Mallon spent in quarantine

74%: Share of Mallon’s stool samples that tested positive during her first quarantine

>400: Asymptomatic typhoid spreaders identified in New York during her lifetime

20%: Share of white-skinned patients who develop typhoid’s characteristic red spots

100: Oxford residents who swallowed the live typhoid bacteria for a vaccine trial in 2015

22 million: Estimated annual typhoid cases worldwide, with 200,000 deaths, mostly children

$1.50: Per-dose cost of the WHO’s preferred typhoid vaccine when purchased for a developing country

Typhoid is the result of infection with a specific strain of Salmonella. (It is not the same as typhus, a vector-borne illness transmitted by fleas, ticks, and the like.) Typhoid typically spreads through contaminated food or water, or close contact with someone who has the bacteria, which they shed in their poop. In most people, the disease causes high fever, headache, and intestinal issues ranging from constipation and diarrhea to intestinal perforation and internal bleeding. If left untreated, it kills about one in three people it infects.

Today, typhoid is rare in developed nations, thanks to the widespread vaccine and good sanitation. But it still persists in many places. It can typically be treated with antibiotics and rehydration. But some people have chronic typhoid, where Salmonella bacteria accumulate in the gallbladder or biliary tract. These carriers may not have symptoms, but can continue to shed the bacteria through fecal matter.

Mary Mallon came to the United States as a teenager. She found employment as a cook for wealthy New Yorkers, and was reportedly quite skilled. But in every kitchen Mallon entered, typhoid fever followed.

In 1906, George Soper, a freelance sanitation engineer, conducted an investigation and traced several outbreaks back to the cook. While Mallon herself never got sick, the bacteria hid inside her and shed itself in her poop. Whether she was really bad at washing her hands, as some people suggest, or her sanitary efforts were simply no match for her condition, Mallon and typhoid traveled together.

Following Soper’s findings, the city took action. In 1907, Mallon was confined to North Brother Island, where she lived in isolation, save for a canine companion, for three years. Public health officials asked to remove Mallon’s gallbladder, which may have stopped her chronic typhoid in its tracks, but she refused. In 1910, the city decided to release her anyway, provided she never again work in food preparation. “She has been released because she has been shut up long enough to learn the precautions that she ought to take,” Dr. Ernst J. Lederle, Commissioner of Health, told the New York Times at the time.

Mallon worked as a laundress, but she was never able to make the same wages she could as a cook. So she got herself an alias—Mary Brown—and spent the next five years cooking, spreading typhoid, and eluding the police. In 1915, when public health officials finally tracked her down again, they sent her back to North Brother Island, this time for good. Mallon spent the last 23 years of her life on the island, where she eventually died at age 69 in 1938. In 1939, Soper published a vivid account (pdf) of his detective work, and interactions with Mallon.

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430 BC: A typhoid epidemic, known as the Plague of Athens, originates in Ethiopia and eventually brings an end to the great Athenian age.

1643: English physician Thomas Willis describes typhoid in Treatise on Fevers.

1869: Mary Mallon is born in Cookstown, County Tyrone, Ireland.

1880: Karl Joseph Eberth observes typhoid bacteria for the first time in patient samples.

1883: Mary Mallon immigrates to the US.

1896: Almroth Wright develops the first typhoid vaccine.

1938: Mallon dies of pneumonia. Her New York Times obituary calls her a “human culture tube.”

1942: The development of antibiotics offers a reliable treatment for typhoid.

2001: Anthony Bourdain publishes Typhoid Mary: An Urban Historical, a sympathetic book on the infamous figure.

2018: WHO approves a new and highly efficacious typhoid vaccine.

William Randolph Hearst, the newspaper magnate, may have secretly funded Mallon’s 1909 lawsuit against the health department, according to Judith Walzer Leavitt, author of Typhoid Mary: Captive to the Public’s Health. The drama was certainly good for business.

Mary Mallon never accepted health officials’ explanation of her disease. “I never had typhoid in my life and have always been healthy,” she once wrote. Even today, it’s hard for many to understand the concept of asymptomatic carriers—people who harbor and spread a disease, but never appear to get sick from it themselves.

“We thought the only way to get rid of pathogens was through elimination, either by the immune system or with antimicrobial drugs,” immunologist Miguel Soares tells Quanta. But it’s since become clear that some people tolerate certain infectious diseases while still spreading them. Only a few diseases have known cases of so-called asymptomatic transmission, including the coronavirus, C. diff, tuberculosis, HIV, and certain strains of influenza.

When it comes to typhoid, a 2013 study suggests the bacteria can live in certain parts of the body, like macrophages in the cell or the gut lining or gallbladder, where it’s able to avoid the inflammatory response that destroys the infection in other parts of the body. While Typhoid Mary is the most famous super-spreader, scientists estimate 1% to 6% of people infected with typhoid-causing Salmonella are asymptomatic. Even in early 20th-century America, Mallon was in infamous company: Food worker Tony Labella, Adirondack guide “Typhoid John,” and bakery owner Alphonse Cotils were also known to spread typhoid asymptomatically around the same time.

The concept of “quarantine” comes from the Venetians who, during the Black Death in Europe, forced ships and their crews to remain in the harbor for 40 (or quaranta) days to stop the spread of the bubonic plague. Today it takes diverse forms around the world.

🇹🇼 During the Covid-19 outbreak, Taiwan is keeping tabs on tens of thousands of people on home quarantine with “digital fences” monitored by smartphones; residents can order three free masks per week.

🇭🇰 Hong Kong is currently enforcing home quarantines with bracelets that register a home’s digital fingerprint.

🇰🇷 Quarantined South Koreans are receiving packages with two weeks of basic supplies, like instant food and toothbrushes.

🇫🇷 In March, France banned residents from exercising more than a kilometer from their homes, and for no more than an hour once a day.

Can’t get enough of Mary Mallon? Here’s a boozy, foul-mouthed reenactment of her story from the good folks at Drunk History.

Mary Mallon was quarantined for more than two decades on North Brother Island, a 20-acre speck of land in the East River between Manhattan and Queens. In 1885, Riverside Hospital moved to the island from Roosevelt Island. It originally was a smallpox hospital, but eventually expanded to handle all manner of infectious diseases. It’s now a de facto wildlife reservation, as documented in this 2011 New York Times photo essay.