A major outbreak of typhoid at Sloane Hospital for Women in New York this month 100 years ago, in which 25 were infected and two died, led to the quarantining of an Irish woman for the rest of her life. The woman in question was Mary Mallon, who became known as “Typhoid Mary”.

Born in Cookstown, Co Tyrone in 1869, she emigrated to America at 15 and for some years worked as a domestic servant, as did many Irish immigrant women of the time, but she proved to be a talented cook and that occupation paid more than most other domestic service positions.

Mallon was working for the family of a wealthy banker, Charles Warren, in 1906 when they rented a summerhouse on Long Island. Six of the 11 people in the house came down with typhoid. Typhoid was known to be spread through consuming affected food or water; the family, which had rented their house to the Warrens, wanted to discover the source, fearing they would be unable to rent their house again unless and until they did so.

They hired George Soper, a civil engineer with a specialist knowledge of typhoid outbreaks. He concluded that the Warrens’ recently hired cook was the source. By this time she had left the Warren household and Soper researched her employment history, discovering that she had worked for seven different families since 1900 and that 22 people connected with them had contracted typhoid, including a young girl who died.

To prove scientifically that Mallon was a carrier of the disease, Soper needed blood and stool samples and he approached her in her new place of employment.

It was hardly surprising that a stranger who accused her (although she felt perfectly healthy) of spreading disease and killing someone, and who asked her for some of her blood, wasn’t well received by Mallon. She seized a carving fork and the threatened Soper beat a hasty retreat.

Soper presented his research to the New York City health department, which sent a female official to try to persuade Mallon to cooperate but, getting nowhere, the official returned with five policemen and an ambulance. Mallon did not yield without a fight; the official had to sit on her all the way to the hospital and described it as like being “in a cage with an angry lion”.

Typhoid bacilli were found in her stool at the hospital and she was isolated in a cottage of the Riverside Hospital on North Brother Island in the East River. She could not understand what was being done to her: “I never had typhoid in my life and have always been healthy. Why should I be banished like a leper and compelled to live in solitary confinement with only a dog for a companion?”

After two years of isolation, she sued the health department. Regular stool samples they had taken proved mostly positive but samples she had sent to a private lab all tested negative. The health department won the case and Mallon returned to the isolated cottage but a new health commissioner decided in February 1910 that she could be freed in return for a promise never to work as a cook again.

For some years she worked at other jobs, which did not pay as well. Then came the Sloane Hospital outbreak where the evidence pointed to a newly hired cook, Mrs Browne, who turned out to be Mallon.

She was returned to the isolated island cottage, where she spent the last 23 years of her life.

Why did “Typhoid Mary” become so well known? Although she was the first carrier found, there were an estimated 100-140 carriers a year in the New York of her time. Nor was she the most deadly carrier, having 47 illnesses and three deaths attributed to her.

Another healthy carrier, Tony Labella, caused 122 illnesses and five deaths; he was isolated for two weeks and released.

Was it because she didn’t obey health officials once apprised of her contagious status? Alphonse Cotils, a restaurateur and baker, did just as Mallon had done but was let go on a promise to do his business over the phone.

Judith Leavitt, author of Typhoid Mary, believes there was prejudice against her not only for being Irish and a woman, but for being unmarried, a domestic servant, resisting so vehemently and not believing she was a carrier.

She suffered extreme punishment for something she did not understand and over which she had no control. Despite her mistakes, she hardly deserved the reputation she acquired for being malicious and deceptive and to be forever remembered as Typhoid Mary.