Professionalism/Typhoid Mary

In the early 1900s, disease transmission was still poorly understood and most people did not understand the concept of an asymptomatic carrier. Mary Mallon was a cook who was an asymptomatic (or healthy) carrier of typhoid fever. Through a series of job changes in the New York City area, she initiated many small typhoid outbreaks that, if left unchecked, could have been devastating to the city population.

"Typhoid" Mary Mallon
Born September 23, 1869(1869-09-23)
Cookstown, Ireland
Died November 11, 1938 (aged 69)


In 1900, Irish-born immigrant Mary Mallon started her career as a common cook for a house in Mamaroneck, New York. Within the first two weeks of her employment, some of the residents came down with Typhoid fever.[1] In 1901, Mary moved to Manhattan to start a new job cooking for a different family. During Mallon’s time in Manhattan, several family members she cooked for developed serious fevers, and the family laundress died. She switched jobs once again, and seven of the eight household members developed typhoid fever. Mary continued to repeatedly change employment, and four more households came down with typhoid fever.

By 1906 Dr. George Soper, a New York sanitary engineer, had began to investigate the outbreaks of typhoid fever. The outbreaks were unique in that they all occurred in houses of wealthy families, instead of poorer, less sanitary areas. Soper found that the common element in all of the outbreaks was an Irish cook named Mary. Soper traced Mary back to an active outbreak, and requested urine and stool samples from her. Mary adamantly denied any connection between her and the outbreaks, and refused to give Soper any samples. Later, Soper compiled a 5 year history of Mary's employment, which showed that seven out of eight families that Mary cooked for contracted typhoid fever.[2]

The New York City health department eventually noticed what was happening, and sent public health official Sara Josephine Baker to talk to Mary. Baker stated that Mary “was convinced that the law was only persecuting her when she had done nothing wrong.”[3] A few days later, Baker arrived at Mary’s workplace with police officers to take her into custody. In 1907, Mary was put into quarantine indefinitely.

Three years later, Mallon was told that she could be freed from quarantine, under the condition that she changed occupation and took precautions to prevent transmitting typhoid to others. In 1910 Mary was released from quarantine. Mary began working in the NYC area as a laundress. However, since cooking paid higher wages, she switched her name and started cooking again under an alias. For the next five years she frequently changed jobs, and wherever she worked, there were typhoid outbreaks. Public health officials tracked Mary down after a large outbreak occurred in the Sloane Hospital for Women.[4] In 1915, they returned Mary to quarantine. She would remain there for the remainder of her life. Mary Mallon died on November 11, 1938, and an autopsy found evidence of live typhoid bacteria in her gallbladder.[1]

Mary MallonEdit

A poster demonstrating how Mallon passed typhoid to other people.

Ethics and ProfessionalismEdit

Mary had a long cooking career but experience alone does not title her a professional. According the modern definition of a professional cook from the United States Personal Chef Association [5], Mary lacked knowledge on food safety. She did not regularly wash her hands before preparing food or using the restroom[6]. What she truly lacked was ethical judgement. Even after infecting seven out of eight households, she choose to escape and cook again.

Mary was an Irish Immigrant. This background played a major role in her career because a strong Irish discrimination still lingered in the early 1900s due to the mass immigration of Irish resulting from the Irish potato famine [7]. The first thought that came to Mary's mind when she was approached by Dr. Soper was that she was being targeted because of her race. She held this belief even after she was detained. Even after quarantine, Mary used her opinion to justify her return to cooking.


During her Imprisonment, Mary made many requests to judges for her release. She appealed to the judges through personal letters that described her stolen freedoms and living condition. [8]. She claimed that the other quarantine residents mocked her and called her the "kidnapped woman". Even health officials later outlined how Mary could have been treated better.[9] Mary made unethical decisions, but these decisions were met with unethical treatment.

George SoperEdit

Doctor George Soper was hired by one of the wealthy families to help find the source of the typhoid outbreak. After examining the water and sewage systems, he looked elsewhere. He found out that there had been a cook who had left before the typhoid outbreak. His investigation lead him to other houses where typhoid also broke out. Despite being only a sanitary engineer and not a medical doctor, he was convinced that Mallon held the key to the outbreak.[1] Usually sanitary engineers are focused on improving sanitation through wastewater facilities and sewage systems but during the early 1900s, they were also trying to prevent the spread of diseases.

Soper needed urine and stool samples from Mallon to prove that she was a typhoid carrier. Soper thought he could count on Mallon's cooperation. But Mallon was outraged when Soper accused her for having a disease when she felt no symptoms of typhoid. Soper viewed Mallon as a crazy person because she refused to give something to Soper that could potentially save more people from contracting tyhpoid fever. After being denied the first time, Soper went back against twice to ask Mallon for her cooperation but was denied both times. He eventually gave up and turned things over to Sarah Josephine Baker of the Public Health Department.

Was Soper a professional?Edit

When Soper thought he found the source of the typhoid outbreak, he went door to door to find Mallon. Like a dog who has the scent of a criminal, he would not give up until he found her. Soper had something to prove by finding Mary.[10] Since microbiology and disease contamination was unproven at the time, he had the chance to validate epidemiology. Some say he was chasing after the honors that would make him a hero and a posterboy for scientists.

On the other hand, Soper can be considered a professional engineer by putting the safety of the public and the clients before all else.[11] Soper's dilemma could be applied to all other aspects of engineering. The code of ethics holds the public and the client above everything. But how far do engineers have to go to ensure the safety of the public. Can we infringe on the rights of the people who will be directly impacted by the action? In the typhoid mary case, Mary Mallon had her freedom taken from her in order for the safety of the public. But there might be other cases where a small minority may be negatively affected by the decisions of the engineer. Professional engineers should be careful in all decisions in order to minimize the negative impacts of our decisions i.e., exercising our judgements.

Circumstances of Mary's CaseEdit

Lack of PrecendenceEdit

Mary was the first person in the United States that was identified as an asymptomatic carrier for typhoid. As such, her case was the first of its kind. Public health officials had no previous experience in dealing with an asymptomatic carrier. The NYC public health department had no pre-formulated plan to deal with Mary's case, which resulted in more than one unethical decision. If there had been a precedent to Mary's case, they may have been able to act more quickly and efficiently, and in turn prevent some of the typhoid infections that Mary caused.

Without a previous incident of reckless disease spreading, there was nothing to spur legislation on the matter. When Mary began her cooking career, there were no laws explicitly stating that what Mary was doing was illegal. In order to protect the public safety, the NYC Health Department had to detain and quarantine Mary. New York health officials based their decision to detain Mallon based on section 1169 and 1170 of the Greater New York Charter.[12] But the charter was signed before the discovery of healthy carriers. The charter states that the board may move any "sick" person; however, healthy carriers aren't sick in the strict sense of the definition because they are seen as healthy. Even if an apparently healthy person is more dangerous to the public, following the wording of the charter, they aren't sick and should not be detained.

Limited Knowledge of MedicineEdit

Medicine in the early 1900s was relatively undeveloped compare to today's standard. Especially relevant to Mary Mallon's case is the unproven theory of an asymptomatic carrier. During the same time period, there was another case of an asymptomatic carrier discovered in Germany.[10] News of this reached New York and prompted Dr. Soper to look deeper into the typhoid outbreak. Mary's reluctance to believe that she was infected with typhoid is understandable because most experts are just beginning to understand asymptomatic carriers.

Washing hands before cooking was unheard of in the early 1900s. Medical technology has advanced enough for doctors and nurses to know that more patients get sick when they are treated with unclean utensils. However, germ theory has not advanced far enough for professional cooks make hand washing a common practice.


Mary did not believe that her cooking was harming other people. She did not take responsibility for the typhoid outbreaks, nor did she take precautions to prevent the spread of the disease. Her actions were undeniably selfish and unethical, since she continued to cook even after being told multiple times that she was infecting people with typhoid. Even when she had a job as a laundress, she went back to cooking. She might have the experience of a professional cook, but not the ethics.

In detaining and isolating Mary, Soper and NYC health officials did what they were obligated to do in order to protect the health of the public. However, they failed to truly convince Mallon that she was dangerous to others, and as a result, she returned to cooking, and continued to pass on typhoid fever. They made a poor decision in letting Mary leave quarantine without taking the necessary measures to keep track of her and prevent her from cooking. As a result, she was able to elude Soper and Public health officials for five years while she continued to spread typhoid to others.

"If when Soper appeared on her doorstep she had quietly acquiesced, acknowledged that her cooking career was over and agreed to find another line of work, she probably would never have achieved immortality. Instead, when Soper explained his findings, offered free medical care and asked her to submit samples for testing, Mary Mallon picked up a rolling pin and chased him out of her kitchen."
—Brooks, Janet, The Sad and Tragic Life of Typhoid Mary[13]


  1. a b c Dex and McCaff, "Who was Typhoid Mary?" The Straight Dope, Aug 14, 2000
  2. Satin, Morton (2007). Death in the Pot. New York: Prometheus Books. p. 169. 
  3. Rosenberg, Jennifer. "Typhoid Mary". Retrieved June 6, 2007. 
  4. "Food Science Curriculum" (PDF). Illinois State Board of Education. p. 118. Retrieved February 9, 2011. 
  5. uspca. "Professional Chef Organization". uspca. Retrieved Mars 6, 2013. 
  6. Adam Shatz. "Employees Must Wash Hands". Wash Hand. Retrieved May 13, 2001. 
  7. Library of Congress. "Irish Discrimination". 
  8. PBS. "Typhoid Mary Personal Letter". 
  9. PBS. "Typhoid Mary villain or victim". 
  10. a b Anthony Bourdain, "There's something about Mary"
  11. American Society of Civil Engineers, "Code of Ethics"
  12. Judith Leavitt, "Tyhphoid Mary:Captive to the Public's Health"
  13. Brooks, Jannet. "The sad and tragic life of Typhoid Mary". Retrieved Mars 6, 1996.