Mary Mallon (September 23, 1869 – November 11, 1938), commonly known as Typhoid Mary, was an Irish-born American cook believed to have infected between 51 to 122 people with typhoid fever. The infections caused three confirmed deaths, with unconfirmed estimates of up to 50. She was the first person in the United States identified as an asymptomatic carrier of the pathogenic bacteria Salmonella typhi. Because she persisted in working as a cook, thereby exposing others to the disease, she was twice forcibly quarantined by authorities, eventually for the final two decades of her life. Mallon died after a total of nearly 30 years in isolation.