Mary Mallon (September 23, 1869–November 11, 1938), also known as Typhoid Mary, was an Irish-born cook believed to have infected 53 people with typhoid fever, three of whom died, and the first person in the United States identified as an asymptomatic carrier of the disease. Because she persisted in working as a cook, by which she exposed others to the disease, she was twice forcibly quarantined by authorities, and died after a total of nearly three decades in isolation.
Mary Mallon was born in 1869 in Cookstown, County Tyrone, in what is now Northern Ireland. Presumably, she was born with typhoid because her mother was infected during pregnancy.At the age of 15, she migrated to the United States.She lived with her aunt and uncle for a time and worked as a maid, but eventually became a cook for affluent families.
From 1900 to 1907, Mallon worked as a cook in the New York City area for eight families, seven of which contracted typhoid. In 1900, she worked in Mamaroneck, New York, where within two weeks of her employment, residents developed typhoid fever. In 1901, she moved to Manhattan, where members of the family for whom she worked developed fevers and diarrhea, and the laundress died. Mallon then went to work for a lawyer and left after seven of the eight people in that household became ill.
In June 1904, she was hired by a prosperous lawyer, Henry Gilsey. Within a week, the laundress was infected with typhoid, and soon four of the seven servants were ill. No members of Gilsey’s family were infected, because they resided separately, and the servants lived in their own house. The investigator Dr. R. L. Wilson concluded that the laundress had caused the outbreak, but he failed to prove it.
Immediately after the outbreak began, Mallon left and moved to Tuxedo Park, where she was hired by George Kessler. Two weeks later, the laundress in his household was infected and taken to St. Joseph’s Regional Medical Center, where her case of typhoid was the first in a long time.
In August 1906, Mallon took a position in Oyster Bay on Long Island with the family of a wealthy New York banker, Charles Henry Warren. Mallon went along with the Warrens when they rented a house in Oyster Bay for the summer of 1906.
From August 27 to September 3, six of the 11 people in the family came down with typhoid fever. The disease at that time was “unusual” in Oyster Bay, according to three medical doctors who practiced there. The landlord, understanding that it would be impossible to rent a house with the reputation of typhoid, hired several independent experts to find the source of infection. They took water samples from pipes, faucets, toilets, and the cesspool, all of which were negative for typhoid.