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Mary Mallon

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Mary Mallon was an Irish-born cook who lived in the United States during the late 19th and early 20th centuries.

Mallon-Mary 01
Mallon-Mary 01

She is most famous for being the first person in the U.S. identified as an asymptomatic carrier of Salmonella Typhi. This is a type of bacteria that causes typhoid fever. An asymptomatic carrier is someone who carries a pathogen, or a germ that causes disease, but shows no signs or symptoms of being sick themselves. Because she felt healthy, Mallon did not realize she was spreading a dangerous illness to the people she served.

Salmonella typhi bacteria using a Gram-stain technique
Salmonella typhi bacteria using a Gram-stain technique

The mechanism of her infection spread was linked to her work in the food industry. Between 1897 and 1907, Mallon worked for several wealthy families in New York. During this time, members of four different households contracted typhoid fever. An investigator named George Soper, a sanitation engineer and epidemiologist, began looking for the cause. An epidemiologist is a scientist who studies how diseases spread through populations. Soper first ruled out contaminated water, milk, or other common sources. He then focused on Mallon's cooking habits. He noticed she often prepared foods like ice cream with fresh peaches. These types of foods could serve as an excellent medium for the bacteria to travel from her to the guests.

George Soper
George Soper

Soper's investigation revealed a clear pattern of infection. He mapped out Mallon's employment history and connected it to known typhoid cases. He identified twenty-six specific cases of typhoid that were linked to her work. While many people she served may have already been immune, the connection was strong. Soper developed a hypothesis that Mallon was a healthy carrier. He attempted to collect samples of her blood, urine, and feces to prove this. However, Mallon resisted his efforts, believing she was perfectly healthy. She even used a carving fork to defend herself when officials arrived to speak with her.

The legal and medical response to Mallon was intense. In March 1907, health department officials, including Dr. Sara Josephine Baker, attempted to persuade her to cooperate. When Mallon resisted, she was taken to Willard Parker Hospital. There, doctors tested her stools three times a week. These tests confirmed the presence of Bacillus typhosus, the bacteria that causes typhoid. Because the condition was resistant to drug treatments, and because Mallon refused to have her gallbladder removed, the health department took further action. They transferred her to Riverside Hospital on North Brother Island in New York City's East River.

Riverside Hospital, North Brother Island
Riverside Hospital, North Brother Island

Mallon's time on North Brother Island involved two distinct periods of confinement. In 1907, she was sent to the island to prevent her from spreading the disease. She lived in a small cottage and was allowed some freedom on the island for three years. In 1909, she challenged her confinement in court using a writ of habeas corpus, which is a legal demand to bring a prisoner before a judge. The court ruled against her, citing the 1905 Supreme Court decision in Jacobson v. Massachusetts. This case supported the right of states to enforce laws, like compulsory vaccination, to protect public health.

In 1910, the health commissioner, Ernst J. Lederle, released her from quarantine. Mallon agreed to report to the health department every quarter and promised not to work as a cook again. However, in early 1915, a typhoid outbreak occurred at the Sloane Maternity Hospital. This outbreak resulted in twenty-five cases and two deaths. Mallon was identified as the responsible party in this incident. As a result, she was returned to North Brother Island. She remained in quarantine there until her death on November 11, 1938.

The significance of the Mary Mallon case extends far beyond her individual life. Her nickname, "Typhoid Mary," was coined by health officials and later used by journalists. It became a colloquial term for anyone who spreads disease to others. Her case also raised lasting ethical questions regarding the balance between individual liberty and the requirements of public health. Scientists and historians have reexamined her story during modern outbreaks of diseases like HIV/AIDS, tuberculosis, and COVID-19. Her life serves as a critical example in the study of how single individuals can impact the health of an entire community.

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Salmonella typhi bacteria using a...
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