Typhoid fever
Mary Mallon worked as a cook in various part of the New York area between 1900 and 1907. One of her positions was with a wealthy New York banker, Charles Henry Warren and his family. When the Warrens rented the home of Mr. and Mrs. George Townsend in Oyster Bay for the summer of 1906, Mallon came along. From August 27 to September 3, six of the eleven people in the house came down with typhoid fever. Typhoid fever in Oyster Bay at that time was "unusual," according to three doctors who practiced medicine there.