Typhoid Mary Wasn't the Only Carrier. She Was the Only One Locked Up.

In the summer of 1906, six people fell ill with typhoid in a rented Oyster Bay summer house. The owner, worried no one would let the property again, hired a sanitary engineer named George Soper to find the source. Soper ruled out the water, the milk, and the clams, then started backtracking through the staff. The cook, an Irish immigrant named Mary Mallon, had quit three weeks after the outbreak began. Soper followed her trail through seven previous households and found typhoid in all but one of them.

Mallon herself had never been sick a day. The germ theory was only twenty years old, and the idea of a healthy person who shed bacteria in their stool was newer than that. When Soper tracked her down to a Park Avenue kitchen in March 1907 and asked for samples, she ran him off with a carving fork. The health department came back with police. Lab tests confirmed she was excreting Salmonella Typhi, and she was committed to a cottage on North Brother Island in the East River.

She was released in 1910 on a promise not to cook. She broke it — five years later, working under the name Mary Brown at Sloane Hospital for Women, she infected twenty-five staff and patients. Two died. She was returned to North Brother and stayed there until she died in 1938, twenty-three more years.

Here is the part the nickname elides. By the time of her death, New York City had identified more than 400 other asymptomatic typhoid carriers. Many also worked with food. The state paid some of their rent and helped them find non-cooking jobs. Not one of them was confined the way Mallon was. The first carrier the system caught was the one it never let go.