If you hear the term “Typhoid Mary” today, it is usually about a person who spreads something undesirable, e.g., a common cold.

But the original Typhoid Mary was much more than a germ host. In the first place, Mary Mallon, an asymptomatic carrier of typhoid fever, never considered herself to be a carrier at all. Yet she was the cause of more than 50 serious cases of illness and at least three deaths.

Mary was born in Ireland in 1869. At 14, she emigrated to the United States to live in New York with an aunt and uncle. By the time they died, Mary was already earning a great reputation as a cook. Wealthy New Yorkers competed to hire her for her legendary desserts: peach ice cream was her specialty.

In 1900, two weeks after Mary started a new job, several people in the house developed typhoid. At her next job, the laundress contracted typhoid and died. When Mary began working for a lawyer, his whole household came down with typhoid. In 1906, she accompanied the Warren family on vacation to Oyster Bay, as their cook. The family had scarcely arrived when Mrs. Warren and both of her daughters became ill with typhoid. Shortly afterward, three servants also became ill.

A civil engineer named Dr. Soper was hired to investigate. Soper was intrigued that so many wealthy New Yorkers were contracting typhoid, a disease caused by bacteria found in human and animal waste, typically found in impoverished areas with poor sanitation.

Soper soon discovered Mary Mallon was a link between the outbreaks. There were 22 cases of typhoid, in seven of the eight families who had employed her. Dr. Soper suspected Mary unwittingly transmitted the disease by handling food with unwashed hands.

By the time Soper identified her, Mary no longer worked for the Warrens. There was no sign of her until 1907, when a typhoid outbreak on Park Avenue claimed one life and endangered two others.

Dr. Soper entered the kitchen and told Mary his suspicions; she responded by chasing him out of the house with a large fork.

The doctor was surprisingly sympathetic for a man nearly murdered via utensil, “Having a strange man accuse you of spreading disease and of killing people and then be asked for some of your blood and excrement would make just about anybody skeptical,” he said. But when a second attempt failed, Soper suggested a woman might be better suited for the job.

Enter Dr. Sara Josephine Baker, a woman who was not to be deterred.

After an initial failed meeting, she appeared on the doorstep of the home Mary shared with her boyfriend, with police and ambulance in tow. Mary lunged at Baker with a fork and vanished. Hours later, she was discovered hiding in the outhouse. “She came out fighting and swearing, both of which she could do with appalling efficiency and vigor.”

The furious cook was forced into the ambulance where Dr. Baker “literally sat on her all the way to the hospital.” There, tests confirmed what Drs. Soper and Baker suspected: Mary’s gallbladder was a petrie dish of typhoid salmonella.

Mary said she’d never had typhoid and refused to consent to an extraction. She refused to give up her profession, and brazenly admitted she rarely washed her hands. When the doctors pressed her, she explained condescendingly there was no need to do so. Dr. Baker, who had a way with words, described Mary as “maniacal in her integrity.”

The authorities quarantined Mary in a cottage on North Brother Island, with a fox terrier for company, as a means of preventing future outbreaks. She was tested for weekly, and her results were usually typhoid-positive.

Unsatisfied, Mary sent samples to a private lab, where they tested negative. In 1909, she sued New York City Health Department, claiming she was unfairly persecuted. New Yorkers sympathized with her. She seemed healthy, she’d committed no crime, yet she’d been imprisoned three years without a trial.

At her hearing with the state Supreme Court, Mary pleaded for her release: “My own doctors say I have no typhoid germs. I am an innocent human being. I have committed no crime and I am treated like an outcast.”

The judge ruled for the city and sent Mary back to the island.

In June 1909, New York American was the first to identify Mary Mallon as “Typhoid Mary“. Mary was displeased, to say the least, and penned an abusive letter to the editor. It read in part: “I wonder how the said Dr. William H. Park would like to be insulted and put in the Journal and call him or his wife Typhoid William Park.” Touché!

In February 1910, the Commissioner of Health offered Mary a deal: she would be released, if she promised never to work as a cook again.

Maybe she made the agreement in good faith, but Mary soon learned that a laundress earned a fraction of a cook’s wages. She became “Mary Brown” and resumed her place in the kitchen. As before, she didn’t work anywhere long and departed before the inevitable typhoid outbreak.

Mary evaded the authorities for five years. Then, 25 new cases of typhoid were reported at Sloane Hospital for Women. Investigators headed to the kitchen, where they found Typhoid Mary cooking contentedly.

Mary was forcibly returned to North Brother Island in 1915, where she lived until her death in 1938. Post-mortem tests revealed live typhoid bacteria in her gallbladder.