Who Was Known As Typhoid Mary And Why?

So-called "Typhoid Mary" was an asymptomatic carrier of the bacteria that caused typhoid.
So-called "Typhoid Mary" was an asymptomatic carrier of the bacteria that caused typhoid.

Mary Mallon was an Irish born American cook who was also referred to as Typhoid Mary. She was born on September 23rd, 1869. Mary became the first individual in the US to be recognized as a carrier of bacteria linked to typhoid disease. Throughout her occupation, she is believed to have transmitted the bacteria to about 51 people around the New York area, three of whom died. On two different occasions, Mary was isolated by force by the public health officials, and she eventually died after spending almost 30 years in isolation. She is widely known as Typhoid Mary.

Early Life

Mary Mallon was born in Northern Ireland. It is believed that between 1883 and 1884, Mary migrated to the US when she was a teenager to live with her relatives. For some time she lived with her uncle and aunt before she found a job as a cook for wealthy families around the New York area.

Her Career As A Cook

Mary Mallon found a job in New York as a cook between 1900 and 1907, and she worked for seven different families. It is not clear when Mary contracted salmonella typhi, the bacteria responsible for causing typhoid fever, but she worked for two weeks in 1900 for families in Mamaroneck, New York. She later went to Manhattan area in 1901, and members of the household where Mary worked developed diarrhea and fever and one member died. Mary moved on and got a job in a family of a lawyer, and later left the family after seven members out of the eight family members became sick. In 1906, after two weeks of working in Oyster Bay Long Island, ten members of a family of 11 were admitted to the hospital for typhoid infection. Mary moved on to work for three different families where the same disease was diagnosed among the family members. She later moved on to work for a rich New York banker known as Charles Henry Warren, and out of the 11 members in the family, six were infected with the disease.


Towards the end of 1906, one family hired George Soper who had specialized in studying epidemics of typhoid to investigate the outbreak of typhoid. He established that the family changed their cook about three weeks before the epidemic. Mary, who was the new cook, had remained in the family for a while and left the family after about three weeks following the outbreak of typhoid. Soper linked all the outbreaks to Mary Mallon, and during this time, he was unable to locate her because Mary had already moved to a different location. Soper also found that there was another outbreak in a penthouse along Park Avenue, and it was found that Mary had also been a cook in that location. Soper compiled the history of Mary's employment running for five years because she had refused to give samples to test for typhoid. It was established that seven members out of eight families who had employed Marry had contracted the disease.

The First Isolation 1907-1910

The health department of New York requested Sarah Josephine Baker, who was a physician, to talk to Mary Mallon. Eventually, Baker, with the help of the police, managed to forcibly take Mary to New York’s Willard Parker Hospital for examination. The samples indicated the presence of salmonella typhi, which is responsible for typhoid fever. By 1907, more than 3,000 people around the New York area had been infected with typhoid, and it was believed that Mary Mellon was responsible. After the discovery, Mary was taken to Riverside Hospital where she was placed in isolation, and throughout her isolation, she persistently denied that she was suffering from typhoid and therefore she was not responsible for the epidemic. She remained in isolation at the hospital for three years. Finally, the state commission of health in New York declared that those who were carriers of the disease would not be put in isolation anymore and therefore Mary Mallon was set free on the condition that she will not take a job as a cook and to always take precautions not to infect others. Mary was released on February 19, 1910, and she agreed to look for another occupation, and she gave a reassurance through an affidavit.

Second isolation 1915-1938

When Mary Mallon was released, she got a job as a laundress, an occupation that pays less than what she got when she was a cook. After working for several years, she altered her name, and she was now known as Mary Brown. With the new name, she took up her former vocation as a cook. In the next half a decade, Mary Mallon was employed in different kitchens, and each place she worked there was an outbreak of typhoid. During this time, she changed jobs so frequently, and the authorities could not locate her. In 1915 there was a major occurrence of typhoid, this time at New York’s Sloane Maternity Hospital in Manhattan, where 25 people suffered from the infection, and two of them died. At the time, Mary was working as a cook at the hospital with the name Mary Brown. The police arrested her, and on March 27th, 1915, the public health officials took her, and she was put in isolation on North Brother Island. Mary Mallon remained in isolation for the rest of her life, and later she was permitted to work and was offered a job as a technician in one of the laboratories on the island.


For the remaining days of her life, Mary Mallon was in isolation at Riverside Hospital. She suffered a stroke before her death that paralyzed her. She died at the age of 69 on November 11, 1938, as a result of pneumonia. The post-mortem examination was carried out, and salmonella typhi bacteria were found in her gallbladder. It is believed that Mary Mallon infected many people with typhoid and caused the death of at least three people. Others have estimated that she could have caused up to 50 deaths. Because she kept changing names and refused to cooperate, the exact number of people infected or died out of infection is not known. Mary Mallon became the first-ever asymptomatic typhoid carrier to be recognized by medical science. During that time, there were no guidelines or policy for handling such a situation.

Modern Understanding Of Mallon’s case

In 2013, scientists from Stanford University of Medicine announced that they had made a breakthrough in understanding the asymptomatic carriers of typhoid of people like Mary Mallon. Salmonella typhi could hide in macrophages, which is a type of immune cell. Other people may contract typhoid by consuming water or food that has been contaminated by handling by a carrier. The carriers may be healthy individuals or had experienced previous attacks of typhoid fever and may continue to shed the bacterium causing typhoid. It is recommended that washing of hands with soap before preparing food or touching them, as well as washing utensils with soap and water, could reduce the risk of infection.


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