Mary Mallon as an Example of Unexpected Disease Transmission

It’s often hard to see how someone could so easily transmit infectious diseases due to their associated symptoms, but it’s actually much easier than you think. This is perhaps best demonstrated with Mary Mallon, who is now (and even then) popularly referred to as Typhoid Mary. As a symptomless carrier of the disease, Mallon infected dozens of people, with several of them eventually dying. In this article we take a closer look at the events surrounding Mary Mallon to give you a better idea of how something so dangerous occurred so easily. 

Who was Mary Mallon?

Although typhoid vaccinations are now affordable and easily accessible, this was not always the case – immunisation against Salmonella typhi, or typhoid, was only developed in 1911, and antibiotic treatment was not available until 1948. It was before this that Mary Mallon – who eventually became known as Typhoid Mary – was employed as a cook. Born in Ireland and emigrating to the United States in 1884, Mallon began working as a cook for affluent New York banker Charles Henry Warren in 1906. Although it was originally a very healthy household, from 27 August to 3 September, 6 of the 11 people present in the house developed symptoms related to typhoid fever. The outbreak in the household was eventually traced to Mallon, who was brought in by the New York Department of Health and tested for typhoid. The test came back positive, and she was subsequently transferred to Riverside Hospital, where she was quarantined for two years. Mary was eventually released, and although it was agreed she should no longer work as a cook, she found a new job as a cook under the false name “Mary Brown.” As Mary Brown she contaminated at least 25 people in three months as a cook of Sloane Maternity in Manhattan. Doctors, nurses and staff were infected, with two of them dying. After this she was placed into isolation for the rest of her life.

How Mallon transmitted the disease

Although Mallon carried the virus all of her life, she never actually demonstrated any of its symptoms, which is in part why she denied ever having the disease. Symptoms of typhoid fever include fever, headaches and diarrhea, and due to only suffering a mild flu-like episode, she can be readily identified as an asymptomatic carrier of the pathogen. It is believed by experts that Mallon passed along typhoid germs so readily due to her not washing her hands properly before serving food. Although typhoid germs are ordinarily killed in the heat that would result from ordinary cooking, it is believed she transmitted the germs with one of her signature dishes: ice cream with peaches. Without any cooking whatsoever required, this dessert would have allowed for the seamless transmission of germs to anyone who consumed it. Some of this blame could also be directly laid on authorities, as their careless attitudes in informing Mallon as to why she was being kept would have caused her to further sink into denial. 

Considering Mallon during future outbreaks

Mallon is an excellent example of how viruses and diseases can be spread without the knowledge of the infected. This kind of infectivity continues to this day, such as with the recent coronavirus pandemic, and should help you give you a clearer example of how easily diseases can hide within the human body, damage your health – until it’s too late.