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1.4.3 – LIFE OF AN
EPIDEMIOLOGIST
Mrs. Stewart
Medical Interventions
First Incident
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In March 1985, a nurse epidemiologist in a county
health department noted, while reviewing surveillance
data, three cases in a single month of hepatitis B of
unusual origin. Hepatitis B, or serum hepatitis, is
transmitted through sexual contact and by exposure to
infected bodily fluids, but these three patients did not
seem to have the usual risk factors. All three people
did, however, indicate having received injections at the
same health care facility.
The nurse's immediate questions were: Is this a
coincidence? Did these three cases occur by chance or is
there a link? In this instance, the nurse decided to pursue
an investigation.
Second Incident
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At 8:30 in the morning on August 2, 1976, Dr. Robert B. Craven of
CDC's Viral Diseases Division received a call from a nurse at a Veterans'
Hospital in Philadelphia, Pennsylvania. The nurse reported two cases of
severe respiratory illness, one of which had been fatal. Both people
had attended the annual American Legion Convention held July 21-24 .
By the evening of August 2, 71 more of the people attending the
convention had the same illness, with symptoms of acute onset of fever,
chills, headache, malaise, dry cough, and myalgia. Further conversations
with local and state public health officials revealed that between July
26 and August 2, 18 conventioneers had died. Deaths were due
primarily to pneumonia.
An intense investigation began immediately. The incident became known
as the first outbreak of Legionnaires' disease and led to the discovery
of the gram-negative pathogen, Legionnella pneumophila.
Third Incident
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On October 30, 1989, a New Mexico physician notified the state's health
department of three patients with marked peripheral eosinophilia and severe
myalgia. All three patients had been taking oral preparations of L-tryptophan, a
nonprescription drug sold as a dietary supplement in health food stores. Despite
extensive clinical evaluation and testing, the illness could not be identified.
An investigation followed and resulted in the characterization of eosinophiliamyalgia syndrome, EMS. The investigation implicated a vehicle for exposure—Ltryptophan dietary supplements—before a suspected agent was identified, and
the product was taken off the market. Eventually, the problem was traced to a
contaminant that had been introduced by changes in the production process at a
single manufacturing facility.
These three examples illustrate some of the key reasons for needing applied, or
field, epidemiology:
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They were unexpected.
They demanded a response.
The investigators had to go out into the field to solve the problem.
Epidemiologist Career Journal
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Master’s degree required
Average Salary ~ 63,000 / year or $30.30 / hour
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Assignment:
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 list
at least 10 duties for an epidemiologist
 Reflection:
why not?
Would you become an epidemiologist? Why or
1854 Outbreak
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1831 – 1853
 Cholera
outbreaks all over Europe and London
 It was believed to be spread through the air
 0ver 10,000 died
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Soho 1800’s – slaughter houses, cow sheds, animal
droppings
August 1854 – Broadstreet area
 Major
Cholera outbreak
 By September 10th – 500+ people had died
John Snow
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Anesthesiologist in NY during 1854 outbreak
Realized the broad street pump was common factor
among all sick with cholera
Removed pump which severely decreased outbreak
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“Father of epidemiology”
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Cholera
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Cause: Bacteria - Vibrio cholerae
Symptoms: acute intestinal infection causing profuse
watery diarrhea, vomiting, circulatory collapse and
shock.
 Left
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untreated – 25-50% cases are fatal
Recent: 2011- 58 countries, 589,854 cases and
7,816 deaths
Transmission: Found in water contaminated by feces
& on raw shellfish
Prevention: Treated water (boiled or chlorine) and
modern sewage systems
Mission:
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Assume the role of an epidemiologist
Approach and address the following outbreak
scenario
Task #1
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Working as an epidemiologist, you are called in to a
small, rural middle school. Over fifty students have
reported to the nurse in the last three hours,
complaining of nausea and vomiting.
What do you want/need to know?
 List
5 questions you want to ask
 List ways you will gather answers to your questions
New Information
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This all occurred from 12:30 – 3:30
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Everyone who was sick had already eaten lunch
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Everyone who was sick ate the school lunch
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Now, what do you want to know?
 List
5 new questions.
Task #2
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Given the severe gastrointestinal symptoms of the
students, you suspect a food-borne pathogen.
Something they ate is making these kids extremely
sick
Interview the students about foods eaten from
cafeteria
Assignment:
 Use
info to calculate Attack Rates
Food
Food Survey Results
Ill
Well
Total
Milk
45
24
69
Banana
20
11
31
Cheese Pizza
10
48
58
Chicken Nuggets
Potato Salad
40
43
24
10
64
53
Chocolate Pudding
Ice Cream Sandwich
18
36
10
23
28
59
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Attack Rate
45/69 = 65%
20/31 = 65%
10/58 = 17%
40/64 = 63%
43/53 = 81%
18/28 = 64%
36/59 = 61%
Attack Rate =
Number of people who ate a certain food and became ill
_____________________________________________
Total number of people who ate that food
Assignment:
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Hypothesize:
 Determine
which food product you think is responsible for
this outbreak
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Look up the most common food-borne pathogen (in the
United States) for that food product
Describe how to treat this pathogen
 Treat
symptoms only?
 Other treatment required?
Complete the Task
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You have:
 Identified
the source
 Treated those infected
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You need to:
 Stop
 List
the outbreak from spreading
3 ways to stop this from continuing to infect others
 Prevent
 List
it from happening again
3 ways to prevent it
Choose a disease
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Tuberculosis
Hantavirus pulmonary syndrome (HPS)
Mad cow disease
Avian influenza (bird flu)
Malaria
Lyme disease
Cervical cancer
Legionnaire disease
Plague
Measles
Ebola hemorrhagic fever
AIDS
Smallpox
Polio
Anthrax
West Nile Virus
SARS
Assignment
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Choose one of the following items to complete:
 Write
a short paragraph describing how you are working to
prevent this disease. Make sure to mention your geographical
location and to describe how the action or medication works
to prevent this disease. Describe any barriers you encounter in
delivering health care that are unique to your situation.
 Write
a short paragraph describing your efforts in treating
the disease or designing a new therapy. Make sure to mention
how this treatment stops the symptoms of the disease or cures
the patient. Describe any barriers you encounter in delivering
health care that are unique to your situation.
1.4.3 Conclusion Questions
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Describe at least four ways an epidemiologist could
have helped in handling and analyzing the
outbreak of hemorrhagic fever in Africa.
How do epidemiologists play a role in the
diagnosis, treatment, and prevention of chronic
illnesses, such as cancer or heart disease?
Explain why statistics and math are important tools
for an epidemiologist.
Task #3 – Other responsibilities
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Epidemiologists organize formal studies to test the
possible associations between risk factors and
disease. Not all epidemiologists study infectious
diseases or investigate outbreaks. Many
epidemiologists study the factors that may
contribute to the development of chronic diseases
such as cancer and heart disease. The most common
study designs utilized by epidemiologists to
investigate both infectious and chronic diseases are
the cohort study and the case-control study.
Cohort vs. Case-Control Study
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In a cohort study (also called a prospective study), the
investigator selects a group of exposed individuals (individuals
who have been exposed to the potential risk factor) and a
group of non-exposed individuals and follows both groups
over time to determine the incidence of disease.
In a case-control study (also called a retrospective study), a
group of individuals with the disease are identified (called
cases) and compared to a group of people without the disease
(called controls). Cases and controls are carefully matched on
all criteria other than the one being studied. For example,
cases and controls should be matched for age, gender or for
underlying medical conditions. These individuals can then be
surveyed about their exposure to the given risk factor.
Assignment
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Describe how you would set up both a case-control
and a cohort study looking at the link between
smoking and elevated cholesterol levels.
For each study design, include information about the
participants in the study and describe how you
might analyze study data.
Answer Conclusion questions 2-6.