famous typhoid (typhoid fever) carrier who allegedly gave rise to the most famous outbreaks of carrier-borne disease in medical history.

Mary was first recognized as a carrier of the typhoid bacteria during an epidemic of typhoid fever in 1904 that spread through Oyster Bay, New York, where she worked as a cook. By the time the disease had been traced to its source in a household where she had recently been employed, Mary had disappeared. She continued to work as a cook, moving from household to household, until 1907, when she resurfaced, working in a Park Avenue home in Manhattan.

Again Mary fled, but authorities led by George Soper, a sanitary engineer in the New York City Department of Health, finally overtook her and had her committed to an isolation centre on North Brother Island, off the Bronx, New York. There she stayed, despite an appeal to the U.S. Supreme Court, until 1910, when the health department released her on condition that she never accept employment that involved the handling of food.

Four years later, Soper began looking for Mary again when an epidemic broke out at a sanatorium in Newfoundland, New Jersey, and at Sloane Maternity Hospital in Manhattan, New York; Mary had worked as a cook at both places. She was at last found in a suburban home in Westchester county, New York, and was returned to North Brother Island, where she remained the rest of her life. A paralytic stroke in 1932 led to her slow death, six years later.

Mary's claim to having been born in the United States was never confirmed, nor was her age ever verified. Fifty-one original cases of typhoid and three deaths were directly attributed to her (countless more were indirectly attributed), although she herself was immune to the typhoid bacillus (Salmonella typhi).