Mary Mallon

Mary Mallon (September 23, 1869 – November 11, 1938), commonly known as Typhoid Mary, was an Irish-born American cook who is believed to have infected between 51 and 122 people with typhoid fever. The infections caused three confirmed deaths, with unconfirmed estimates of as many as 50. She was the first person in the United States identified as an asymptomatic carrier of the pathogenic bacterium Salmonella typhi. She was forcibly quarantined twice by authorities, the second time for the remainder of her life because she persisted in working as a cook and thereby exposed others to the disease. Mallon died after a total of nearly 30 years quarantined. Her popular nickname has since become a term for persons who spread disease or other misfortune.

Mary Mallon was born in 1869 in Cookstown, County Tyrone, Ireland. She may have been born with typhoid fever as her mother was infected during pregnancy. In 1884 at the age of 15, she emigrated from Ireland 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 whom contracted typhoid. In 1900, she worked in Mamaroneck, New York, where within two weeks of her employment, residents developed typhoid fever. In 1901, she relocated to Manhattan, where members of the family for whom she worked developed fevers and diarrhea. 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. Soon four of the seven servants were ill. No Gilsey family members were infected because they resided separately, and the servants lived in their own house. Immediately after the outbreak began, Mallon left and relocated to Tuxedo Park, where she was hired by George Kessler. Two weeks later, the laundry worker 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. The investigator Dr. R. L. Wilson concluded that the laundry worker had caused the outbreak, but he failed to prove it. The laundry worker died soon afterward.

In August 1906, Mallon began a job in Oyster Bay on Long Island with the family of a wealthy New York banker, Charles Elliot 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 contracted typhoid fever. According to three medical doctors, the disease at that time was "unusual" in Oyster Bay. The landlord, understanding that it would be difficult to rent a house with the reputation of having typhoid, hired several independent experts to find the source of the infection. They took water samples from pipes, faucets, toilets, and the cesspool, all of which were negative for typhoid.

George Soper, an investigator hired by the Oyster Bay property owner after the outbreak there, had been trying to determine the cause of typhoid outbreaks in affluent families, when it was known that the disease typically occurred in unsanitary conditions. He discovered that a female Irish cook, who fit the physical description he had been given, was involved in all of the outbreaks. He was unable to locate her because she generally left after an outbreak began, without giving a forwarding address. The Park Avenue outbreak helped to identify Mallon as the source of the infections. Soper learned of the case while it was still active and discovered Mallon was the cook.

Soper first met Mallon in the kitchen of the Bownes' Park Avenue penthouse and accused her of spreading the disease. Though Soper himself recollected his behavior "as diplomatic as possible", he infuriated Mallon and she threatened him with a carving fork. When Mallon refused to give samples, Soper decided to compile a five-year history of her employment. He found that, of the eight families that had hired Mallon as a cook, members of seven claimed to have contracted typhoid fever. Then Soper learned where Mallon's boyfriend lived and arranged a new meeting there. He took Raymond Hoobler to persuade Mary to give them urine and stool samples for analysis. Mallon again refused to cooperate, claiming that typhoid was everywhere and that the outbreaks had happened because of contaminated food and water. At that time, the concept of healthy carriers was unknown even to healthcare workers.

Soper published his findings on June 15, 1907, in the Journal of the American Medical Association. He wrote: