Mary Mallon Cooked for Wealthy Manhattan Families and Spent Three Years Quarantined for It

Mary Mallon was a 37-year-old Irish-born cook in 1906, working for the wealthy Warren family in Oyster Bay on Long Island, when six of the eleven people in the house contracted typhoid fever within two weeks. The Warrens hired the sanitary engineer George Soper to investigate. Soper went through Mallon's job history. At every household she had cooked for since her arrival in the United States — the Mallon family in Mamaroneck, the Drayton home, the Thompson household, the Warrens — there had been an outbreak of typhoid shortly afterward. He traced 22 distinct cases of typhoid to Mallon by the time he confronted her at the Warrens' home in 1906, demanding samples of her stool, urine, and blood. "She seized a carving fork," Soper later wrote, "and advanced in my direction."

The theoretical possibility of an asymptomatic carrier — somebody continuously shedding Salmonella Typhi without ever feeling ill — was not yet established medical practice. New York health officials physically restrained Mallon in March 1907 with the help of police and Dr. Sara Josephine Baker, who reportedly sat on Mallon's chest in the ambulance. They confined her in a small cottage on North Brother Island in the East River. Tests confirmed the carriage; her gallbladder was thought to be the reservoir. She refused surgery to remove it.

She was released in 1910 on the condition that she never cook again, and immediately took a kitchen job under the alias Mary Brown. Five years later an outbreak of typhoid at Sloane Hospital for Women was traced to her. She was returned to North Brother Island in 1915 and stayed there until her death in 1938. By then over 400 asymptomatic typhoid carriers had been identified in the United States. None of the others were detained for more than a few months.