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1. Copyright © 2021 by Jones & Bartlett Learning, LLC an Ascend Learning Company. www.jblearning.com.
CHAPTER 4
Epidemiology:
The Basic
Science of
Public Health

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Epidemiology
 Is the diagnostic discipline of public health
 Is a major part of public health’s assessment function
 Investigates causes of diseases
 Identifies trends in disease occurrence
 Evaluates effectiveness of medical and public health interventions

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Patterns of Disease Occurrence
 From the following information, epidemiologists can infer why a disease is
occurring:
 Who is getting the disease?
 When did they get the disease?
 Where is the disease occurring?
 The ultimate goal is to use this knowledge to control and prevent the spread of
disease.

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Epidemic Surveillance
 Is a major line of defense in protecting the public against disease
 Important terms are:
– Endemic versus epidemic
– “Notifiable” diseases
– “Shoeleather epidemiology”
 System was created to control spread of known disease but also aids in
recognizing new disease.
 Importance has increased with threat of bioterrorism.

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2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
John Snow and Cholera
 First example of use of epidemiology to study and control a disease was by
Snow for cholera.
 London had Cholera epidemics in mid-1800s.
 Snow suspected an association with the water supply, the Thames River.
 He conducted a “natural experiment”:
– He questioned households where cholera death had occurred.
 Most deaths were associated with one water supply company.

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2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Outbreak Investigation
 Verify the diagnosis.
 Construct a working case definition.
 Find cases systematically.
– Apply active surveillance.
 Ask who, where, and when questions to describe the epidemic by person,
place, and time.
– Consider the incubation period.
 Look for a common source of exposure.

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Epidemiology and Chronic Diseases
 Identify risk factors.
 Observe long-term trends.
 Epidemiologic studies of chronic diseases are more complicated and difficult
than for infectious diseases or toxic contamination.
 Heart disease is leading cause of death in the U.S.
– Framingham Study (started in 1948)
 Lung cancer and smoking studies followed in the early 1950s.
– British study of physicians
– Hammond–Horn study in the U.S.

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2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 1
 Why is epidemiologic surveillance important for public health?
 What role would it play if there were a bioterrorist attack?

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2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 2
 What has epidemiology contributed to people’s understanding of:
– Heart disease?
– Lung cancer?

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2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 3
 Visit the website of The Epidemiology Monitor, a weekly newsletter about
epidemiology, and read the free news updates available on Mondays,
www.epimonitor.net.
 What issues are epidemiologists concerned about this week?

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2021
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Jones
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Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 4
 Visit the website of CDC’s Morbidity and Mortality Weekly Report,
www.cdc.gov/mmwr.
 Has the CDC reported any new outbreaks or health risks this week?
 What other issues is the nation’s epidemiology agency concerned about this
week?

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2021
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Jones
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Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 5
 Visit the website of the Framingham Heart Study, www.framingham.com/heart.
 What are the most recent findings from this cohort study?