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Most Dangerous Woman in America, The
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Classroom Activity
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Objective
To test the efficacy of different types of hand hygiene.
- 2 14.5 oz. cans of sliced beets (10-12 slices per can)
- can opener
- 1 pair new plastic gloves
- plastic forceps or tongs
- isopropyl alcohol (for disinfecting)
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copy of the "Which Wash Wins?" student handout (PDF
or
HTML)
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copy of the "Hand-Washing Methods" student handout (PDF
or
HTML)
- 3 100 mm x 15 mm sterile plastic Petri dishes
- cotton swabs
- tape
- permanent marker
- access to sink with water (Teams 1, 2, and 3 only)
- regular soap (Team 2 only)
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antibacterial soap (with antiseptic like triclosan) (Team 3 only)
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hand sanitizer (with ethyl or isopropyl alcohol) (Team 4 only)
- paper towels (Teams 1, 2, and 3 only)
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Mary Mallon was a healthy carrier of the typhoid bacteria.
Because she was a cook and handled food, she transmitted the
disease to some of the people she worked for. Hand washing is
one way to help stem the transmission of disease. In this
activity students will test the efficacy of different types of
hand hygiene.
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Prior to the activity, thoroughly disinfect the tongs by
spraying or soaking them in alcohol (you may want to wash the
can opener and tongs in a dishwasher and store them in a plastic
bag prior to disinfecting). (Note: To increase the sterility of
the experiment, consider using sterile agar plates instead of
the beets.)
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Ask students if they have ever seen a sign in a restaurant
bathroom that read: "Employees must wash hands." Why do students
think these signs are there?
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Ask students what they think would be the best way to keep hands
clean. What kinds of products, if any, do they think would be
best? What water temperature? What amount of time spent washing?
Write students' answers on the board.
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Tell students that they are going to test four methods a fifth
group will serve as the control of hand hygiene (you may want to
adapt these methods to reflect students' suggestions): 1) water
only, 2) regular soap, 3) antibacterial soap, and 4) hand
sanitizer.
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Organize students into five teams of four students each and
provide each team with a set of materials. Each team will be
assigned one of the following variables:
Control Team: no washing method
Experimental Team 1: washing with water only
Experimental Team 2: washing with regular soap and
water
Experimental Team 3: washing with antibacterial soap and
water
Experimental Team 4: washing with hand sanitizer only
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Have each team develop a hypothesis of which of the four methods
it thinks will work best and why. Then have students conduct the
experiment as outlined in their handouts. As students start
their hand-washing techniques, put on the plastic gloves and
open the two cans of beets. Have each team use the tongs to
retrieve three beet slices, one for each of the team's three
Petri dishes. You may want to disinfect the tongs with alcohol
between team uses.
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Have students record the results in a journal each day, making
sure to include diagrams. After four days, compare the growth on
the beets from the different teams. As a class, answer the
following questions:
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How did each set of beets compare to the control team's
beets?
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Which experimental team's beets had the least bacteria?
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What areas (palms, in between fingers, under nails) were
washed the most thoroughly by each technique? What areas
were washed the least thoroughly?
Was there any growth on the control beets?
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Discuss the results with students. What results were most
surprising? It's likely that all the beets showed some microbial
growth because the experiment was not completely sterile.
Discuss with students where microorganisms might have come from
(beet, plastic tongs, cotton swab, Petri dish, tap water, air).
How could the experiment have been made more sterile?
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To conclude, discuss with students why and when it is
appropriate to wash hands.
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As an extension, have students research the controversy about
whether using antibacterial soaps encourages the growth of new
bacteria that are resistant to these products.
Beet Disposal
The beets used in this experiment should just contain normal molds
and bacteria. The beet slices can remain in their Petri dishes and
be disposed of in the regular trash. Spray with a disinfectant, such
as Clorox, prior to disposing. Make sure students do not touch the
beets after sealing their Petri dishes.
You may want to review the following terms with students:
bacteria: microscopic, single- celled organisms that can be
helpful or harmful to the human body
contagious: able to be transmitted to others, through direct
or indirect contact
epidemiology: branch of medicine that studies the causes,
distribution, and control of diseases in populations
infectious: capable of causing an infection
quarantine: enforced isolation or restriction of a person or
persons to slow or halt the spread of a contagious disease
An individual can have an infection yet not be contagious. For more
information on contagious diseases, including incubation and
contagious periods for specific diseases, see
www.childrenshospitaloakland.org/health_library/pa/hhg/incubate.htm
Molds and some kinds of bacteria are most likely to grow on the
beets. The molds will probably look fuzzy green or white while the
bacteria may be one of several colors (such as pink, yellow, or
brown) or colorless and look shiny or dull. The bacteria are likely
to grow in lawns (individual colonies that merge together to form a
mat of bacteria). The beet provides the nutrients and water the
bacteria and molds need to grow.
The growth on the beets provides evidence that microorganisms can be
transmitted by hands. One strength of that evidence is that all of
the control beets likely showed growth while the beets for the teams
that used antibacterial soap and hand sanitizer likely showed less
growth. One weakness is that the experiment was not entirely
sterile; bacteria and mold from several sources could have
contaminated the beets.
According to the Centers for Disease Control (CDC), plain soap is
good at reducing bacterial counts, antibacterial soap is better, and
an alcohol-based handrub is the best. However, students' results may
vary depending on how well they washed their hands with each type of
cleaner. You may want to repeat the experiment with students and
have them wash their hands for a full minute and compare results of
both trials.
Remind students that while their hands contain many harmless
bacteria, they can also transmit bacteria and viruses that can cause
illness. According to the Centers for Disease Control, one of the
most important steps individuals can take to keep from getting sick
is to wash their hands.
Both alcohol-based sanitizers and antibacterial soaps can kill
harmful bacteria, such as streptococcus, salmonella, and E. coli,
but do not claim to kill viruses (although some viruses are
susceptible to these cleansers). Sanitizers work by using alcohol to
kill the bacteria (they usually contain 60% to 95% ethanol or
isopropanol). Antibacterial soaps rely on an antiseptic agent, such
as triclosan, to kill the bacteria. Regular soap, which can remove
bacteria through the action of its bubbles, is not designed to kill
bacteria or viruses.
Hands should be washed at the following times: before, during, and
after preparing food; before eating; after using the bathroom; after
exposure to animals or animal waste; after handling garbage; after
coughing, sneezing, or blowing your nose; and if you are sick or
have been around a sick person.
Because bacteria can be transmitted to food, it is especially
important that people involved with food preparation (as Mary Mallon
was) frequently and properly wash their hands so they do not spread
disease by fecal-oral transmission. For a full list of when food
employees are supposed to wash, see
vm.cfsan.fda.gov/~dms/fc-2.html#2-3
Web Sites
NOVA Web Site—The Most Dangerous Woman in America
www.pbs.org/nova/typhoid/
Find articles, interviews, interactive activities, and resources in
this companion Web site to the program.
The Living City
156.145.78.54/htm/home.htm
Reviews in time line format the life, health, and urban
transformation of New York City during the decades between the end
of the Civil War and the end of World War I.
Stalking the Mysterious Microbe
www.microbe.org/
Provides background information on microbes and experiments.
Typhoid Mary
history1900s.about.com/library/weekly/aa062900a.htm
Reviews the story of Mary Mallon and provides links to additional
information about typhoid fever.
What Should Be Done About Mary Mallon
www.learner.org/channel/workshops/primarysources/disease/activities01.html
Includes discussion questions related to Mary Mallon's case and
provides access to related primary source documents.
Books
Baker, S. Josephine.
Fighting for Life.
New York, Arno Press,1974 [c1939 ].
Provides an autobiographical look at the life and work of S.
Josephine Baker, one of the first public health officers who
approached Mary Mallon.
Bourdain, Anthony.
Typhoid Mary: An Urban Historical.
New York: Bloomsbury Publishing,2003.
Reveals the context in which Mary Mallon lived and the obstacles she
faced as an Irish woman immigrant.
Diner, Hasia R.
Erin's Daughters in America: Irish Immigrant Women in the
Nineteenth Century.
Baltimore: Johns Hopkins University Press, 1983.
Portrays the story of a group of Irish immigrant women who overcome
barriers of poverty, ignorance, and disease to succeed in America.
Hammonds, Evelynn Maxine.
Childhood's Deadly Scourge: The Campaign to Control Diphtheria in
New York City,1880-1930.
Baltimore: Johns Hopkins University Press,1999.
Explains how New York City became the first U.S. city to apply
laboratory-based advances in bacteriology and immunology to the
treatment and prevention of diphtheria.
Kraut, Alan M.
Silent Travelers: Germs, Genes, and the "Immigrant Menace."
New York: Basic Books,1994.
Covers immigration and health from a historical perspective, and
includes accounts of how immigration and public health policies have
influenced each other in the American experience.
Walzer Leavitt, Judith.
Typhoid Mary: Captive to the Public's Health.
Boston: Beacon Press,1996.
Explains the science of germ theory and explores the conflicting
perspectives of the players in Mary Mallon's story, including
journalists, public health officials, the law, and Mary herself.
NOVA's "The Most Dangerous Woman in America" was based on this book.
The "Which Wash Wins?" activity aligns with the following National
Science Education Standards:
Grades 5-8
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Science Standard F: Science in Personal and Social
Perspectives
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Risks and benefits:
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Individuals can use a systematic approach to thinking critically
about risks and benefits. Examples include applying probability
estimates to risks and comparing them to estimated personal and
social benefits.
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Important personal and social decisions are made based on
perceptions of benefits and risks.
Grades 9-12
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Science Standard F: Science in Personal and Social
Perspectives
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Personal and community health:
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The severity of disease symptoms is dependent on many factors,
such as human resistance and the virulence of the
disease-producing organism. Many diseases can be prevented,
controlled, or cured. Some diseases, such as cancer, result from
specific body dysfunctions and cannot be transmitted.
Classroom Activity Author
Developed by WGBH Educational Outreach staff.
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