Whenever I see people going into Mary Brown’s for chicken & taters, I can’t help but chuckle. Mary Brown was the assumed name of an infamous carrier of Salmonella typhi (the microbe that causes typhoid fever). “Typhoid Mary” spread disease while working as a cook. She posed such a threat to the public that she spent the last 23 years of her life in forced isolation!

Mary Mallon was born in 1869 in Cookstown, Ireland, before emigrating to the US to cook for wealthy households. When one of these well-to-do families suffered an outbreak of typhoid fever, George Sober (a sanitary engineer) was commissioned to investigate. Typhoid fever usually spread among the poor in unsanitary slums, so this case was peculiar. At the time, typhoid fever was fatal in 10% of cases with antibiotic treatment unavailable until 1948. Sober pursued a few red herrings before his attention turned to the cook, Mary Mallon.

Mallon refused to cooperate with Sober’s investigation. She was unwilling to submit stool and urine samples and could not see the value in handwashing because she felt perfectly healthy.

Sober discovered that seven families who Mary previously served had reported typhoid illness and death. When Mary Mallon was taken into custody and samples were forcibly obtained, they tested positive for typhoid. Doctors offered to remove her gallbladder to stop her shedding the microbe, but Mary refused. With Mary’s stubbornness posing a threat to public health, she was forced into quarantine.

After three years in isolation, Mary was released under the agreement that she would not work as a cook and that she take reasonable steps to prevent infecting others. After her release, however, Mary assumed false names and continued to work as a cook, changing jobs frequently.

In 1915, Manhattan’s Sloane Maternity Hospital experienced an outbreak of typhoid fever resulting in two deaths. An investigation was launched. The staff at the hospital had a nickname for their hospital’s cook: “Typhoid Mary.” The cook was, in fact, Mary Mallon! She was working under the assumed name of Mary Brown. After her second apprehension, Mallon spent the last 23 years of her life in forced isolation until her death on November 11, 1938.