Supplemental File S3: Typhoid Mary case teaching notes
The Case of Typhoid Mary
In the early 1900s, Mary Mallon worked as a cook in New York. At that
time, she was known for her peach melba; today she is best known for her
ability to spread typhoid fever. Known as “Typhoid Mary”, she has been
credited with starting seven epidemics and infecting more than 50 people
within a 10 year period. In 1907, she was sentenced to live in an isolated
cottage on Brother Island, New York. In 1910, she was released after
agreeing to not work as a cook again. However, Mary did take more
cooking jobs and continued to cause outbreaks of typhoid including one
in a hospital that infected 25 people and killed two. She was tracked
down in 1915 while she was working under an assumed name. She was
returned to Brother Island and lived out her remaining 23 years in
relative isolation. Mary died in 1938 at the age of 69.
In the United States today, there are approximately 5700 cases of typhoid/year; most of these are
acquired during international travel. In contrast, typhoid remains a significant health concern in
the developing world where about 21 million people/year are affected. The etiologic agent of
typhoid is Salmonella enterica subtype Typhi (S. Typhi). Found only in humans, S. Typhi is a Gramnegative motile rod. After ingestion of contaminated food or water, S. Typhi survives passage
through the stomach to reach the intestines and establish infection. Infected people carry S. Typhi
in their blood and intestine; it is shed via feces. S. Typhi is transmitted to a susceptible host by
ingestion of contaminated food or water. Mary Mallon was a lifelong carrier of S. Typhi. While she
reported never having typhoid, she shed S. Typhi in her feces until she died.
Approximately 1-2 weeks after ingestion symptoms will appear. During the 1st week, the symptoms
are somewhat general--headache, fever, general malaise. Definitive diagnosis can be made by
testing blood or stool for S. Typhi. During this stage, patients may feel
exhausted and experience a loss of appetite. During the second week, the
fever may rise to 104∘F. Patients may experience delirium and about 10%
of patients develop a rose-colored rash. The abdomen may become
distended; diarrhea or constipation is associated with this stage of
infection. Without treatment, the infection will grow more severe and can
lead to intestinal perforation and hemorrhage; death occurs in about 20%
of cases. Typhoid can be treated with antibiotics and there is a vaccine
available. Typhoid can be treated with antibiotics; without treatments,
the illness can last 3-4 weeks and death may occur.
Image credits:
S. Typhi image: Public Health Image Library #16877
General Research Division, The New York Public Library. "Typhoid Mary." New York Public Library
Digital Collections. Accessed June 5, 2015. http://digitalcollections.nypl.org/items/85674452-ba9e6934-e040-e00a180606cf
Supplemental File S3: Typhoid Mary case teaching notes
1) Mary Mallon caused 7 epidemics during her lifetime. What is an epidemic? How does it differ
from a pandemic or endemic disease?
Epidemic refers to a disease occurring in an area or population at a rate that is higher than usual. It
differs from pandemic disease in that a pandemic refers to an epidemic occurring on more than one
continent at a given time. Endemic disease is that which occurs at a nearly constant incidence in a
given population or area.
Visuals: Image depicting endemic, sporadic, epidemic, and pandemic disease.
Discussion extension: After using visual to reiterate student responses, ask the class to come up
with examples for each type of disease frequency.
2) In this case, what was the reservoir of disease?
Mary was the reservoir for the disease.
Visuals: Images of various reservoirs—animals (zoonoses), humans, nonliving (water, food, soil).
Discussion extension: Ask students to come up with examples for each type of reservoir. What are
some of the challenges for controlling diseases with the various reservoirs?
3) Mary’s job as a cook facilitated transmission of the typhoid to others. The transmission of
typhoid via food represents what mode of transmission? What would be the portal of entry? What
was the portal of exit?
Foodborne transmission is a form of vehicle transmission. The portal of entry was the mouth and exit
was the anus (feces).
Visuals: Images of modes of transmission (vehicle, vector, direct contact, indirect contact) and
images of portals of entry and exit.
Discussion extension: Briefly cover portals then show transmission modes and discuss likely
portals of entry and exit for each. For example, vehicle transmission images could include aerosols,
water, food, and bodily fluids. Aerosol entry and exit are likely via mouth, nose, and eyes. Water
and food are likely mouth or nose entry and exit via the anus or secretions. Bodily fluids entry and
exit likely via mouth, vagina, or anus.
4) S. typhi produces a variety of adhesins including multiple types of fimbriae. Why are adhesins
important in pathogenesis?
Adhesins are important because they mediate the initial interactions of a pathogen with the host.
Visuals: Image of a bacterium interacting with a host cell; emphasize the ligand/receptor
interactions that occur.
Discussion extension: What types of molecules could function as adhesins? If you had a strain of S.
Typhi with mutated fimbriae do you think it would be as effective at causing disease as the wild type
strain?
Supplemental File S3: Typhoid Mary case teaching notes
5) What is the relationship between the terms pathogenicity and virulence?
Pathogenicity refers to the ability of an organism to cause disease and virulence refers to the degree of
pathogenicity.
Discussion extension: Pose a thought question to students—“could a pathogen be highly virulent
and cause mild disease?” or “can you think of a situation where a less virulent organism could cause
significant disease?” This opens the discussion to clarify virulence as the degree of pathogenicity
and the concept of a virulence continuum. Also allows for clarification that virulence and
pathogenicity do not explain the severity of disease.
6) Like all pathogens, S. typhi produces a variety of virulence factors during infection. What are
virulence factors? Provide 2 general examples of virulence factors.
Virulence factors are traits that contribute to an organism’s ability to cause disease. Examples
include enzymes, toxins, antiphagocytic factors.
Visuals: Images of basic virulence factors—extracellular enzymes (hyaluronidase, collagenase,
coagulase); exotoxins and endotoxin; antiphagocytic factors.
Discussion extension: Options: 1) Compare 2 pathogens, their “palettes” of virulence factors and
their ability to cause disease. Examples: S. Typhi and P. aeruginosa. 2) Relate virulence factor
production to clinical outcomes. Examples: E. coli and endotoxic shock. 3) Relate to experimental
example such as Griffith’s classic experiments demonstrating the role of capsule in virulence.
7) Draw a graph showing the course of the disease and the relative number of S. typhi over time.
Label the five stages of the disease on your graph. Hint: the case provides you information about
the progression of the disease—use this to guide you!
2
3
4
5
1: Incubation
2: Prodromal
3: Illness
4: Decline
5: Disease
Relative # of S. Typhi
1
Time
Discussion extension: Discuss the pieces from the narrative that correspond to each stage. Why
does the period of illness correspond to the greatest number of bacteria? What factors impact the
length of each stage?
Supplemental File S3: Typhoid Mary case teaching notes
After listening to the RadioLab story and reading the NY Times article, answer the following:
8) Describe George Soper’s approach in determining the cause of the typhoid outbreaks. A flow
chart of his steps might be an effective way to approach this.
Soper called to Warren vacation home in Oyster Bay
↓
Soper reviews findings from earlier investigators.
Questions household members and compiles a list of visitors for the past 10 years
↓
Examines medical records of all visitors
↓
Discovers that a couple weeks before the outbreak the Warrens hired a new cook.
That cook is now missing!
↓
Goes to employment agency and determines cook’s previous employers. Finds out that in every
household where she worked there had been a typhoid outbreak
↓
Tracks Mary Mallon down at a home where she is working as a cook. Confronts her demanding blood,
urine, and feces samples. Mary “comes at him” with a serving fork!
↓
Soper enlists the help of S. Josephine Baker in getting the samples from Mary. Baker is met with same
resistance as Soper. Baker gets the police involved
Visuals: Generate the flow chart using step-by-step input from students. Can be done as a
powerpoint slide or on a whiteboard, chalkboard, etc.
Discussion extension: Ask students questions as the flow chart develops. Why was it important
that Soper reviewed all the records of the earlier investigators? Why were people surprised that
the outbreaks were occurring in well-to-do families? Why was Mary so enraged when confronted
by Soper and Baker?
9) What type of epidemiological study was Soper conducting?
Soper was conducting a descriptive study.
Visual: The visual was generated during the discussion of this question.
Discussion extension: Ask students why Soper’s study was descriptive. A powerpoint slide can be
generated during the discussion to outline the characteristics of a descriptive study. (This could
also be done on a whiteboard or other visual device). Then ask students what the other types of
epidemiological studies are and list the characteristics of each type. What are the benefits of each
type of study? In other words, how does each contribute to the public health response to disease?
10) How does the work that Soper was doing differ from etiology?
Etiology studies the causation of disease whereas epidemiology studies where and when diseases occur
and their transmission.
Visuals: Image of Koch’s postulates
Supplemental File S3: Typhoid Mary case teaching notes
Discussion extension: Contrast the work that Soper did with that of Koch. Draw attention to the
fact that Soper wasn’t looking for causative agent, he was looking for where the disease was
occurring and how it was being transmitted. Koch was looking to identify the causative agent, he
didn’t focus on transmission or the time and place of infection.
11) Based on the RadioLab piece, you know that Mary was not the only person that was identified
as a carrier in New York. So why was Mary the only one quarantined on Brother Island? Why is she
the only one that we talk about today? Judith Leavitt, author of Typhoid Mary and guest in the
RadioLab piece, thinks that there was prejudice against Mary for being Irish and a woman, and also
for being a domestic servant, not having a family, not being considered a "bread earner," having a
temper, and not believing in her carrier status. What do you think? Pay attention to the historical
context—we are talking about events that occurred in the early 1900’s, not the present day.
Discussion extension: The discussion will be student-directed based on their answers. Some
additional questions instructors might ask to further stimulate discussion include: What do you
think about the fact that Mary went back to work as a cook after her initial release from Brother
Island? What were the employment “options” for an unmarried women at the time? What do you
think about the fact that other carriers of typhoid were identified but none were sentenced to
Brother Island like Mary even though some of them (mostly males) were working as cooks? Do you
think Mary’s imprisonment was, as Jad Abumrad suggests, to make people feel safe?
Sources:
Leavitt, J.W. 1996. Typhoid Mary: Captive to the Public's Health. Beacon Press, Boston, MA.
Bourdain, A. 2001. Typhoid Mary: An Urban Historical. Bloomsbury, New York, NY.
http://www.cdc.gov/