This document discusses epidemiology and its role in disease prevention. It defines epidemiology as the study of health and disease in populations. Key figures in the development of epidemiology mentioned include John Graunt, William Farr, and John Snow. The document also discusses epidemiologic models like the triad and wheel of causation. It explains how epidemiologic principles are applied in practice, including for community health assessments, disease prevention and control, and evaluating health services.

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Chapter 5: Epidemiology:
The Science of Prevention

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Chapter Highlights
• Defining epidemiology
• Development of epidemiology as a science
• Epidemiologic conceptual frameworks
• Applying epidemiologic principles in practice
– Assessment of health needs and assets
– Using assessment data for planning and implementing
interventions
– Promoting healthy lifestyles
– Preventing and controlling outbreaks
– Contributing to a safe and healthy environment
– Evaluating the effectiveness of health services

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Question
Is the following statement True or False?
Epidemic—an outbreak that occurs when there is an
increased incidence of a disease beyond that which is
normally found in the population

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Answer
True
Rationale: Epidemic—an outbreak that occurs when there
is an increased incidence of a disease beyond that which
is normally found in the population

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Defining Epidemiology
• Epidemiology—study of the distribution and determinants
of states of health and illness in human populations; used
both as a research methodology used to study states of
health and illness, and as a body of knowledge that
results from the study of a specific state of health or
illness
• Epidemic—an outbreak that occurs when there is an
increased incidence of a disease beyond that which is
normally found in the population
• Rates—the primary measurement used to describe either
the occurrence or the existence of a specific state of
health or illness

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Question
Who is perhaps the best known epidemiologist of the 19th
century?
A. John Graunt
B. William Farr
C. John Snow
D. Florence Nightingale

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Answer
C. John Snow
Rationale: Perhaps the best known epidemiologist of the
19th century was John Snow, a contemporary of William
Farr. One of the first people to study patterns of disease
in populations was a London haberdasher, John Graunt.
Farr set up a system for consistent collection of the
numbers and the causes of deaths. Florence Nightingale,
the daughter of a wealthy Englishman, was also a
contemporary of William Farr and John Snow. She
devoted her life to the prevention of needless illness and
death.

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Development of Epidemiology as a
Science
• Early attempts at understanding the reasons for disease
were primarily a direct result of trial and error
observations of individual people.
• John Graunt and the Bills of Mortality
• William Farr, Registrar General
• John Snow and the Broad Street Pump
• Florence Nightingale, Nurse and Epidemiologist

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Question
Is the following statement True or False?
Wheel of causation is the classic model based on the
belief that health status is determined by the interaction
of the characteristics of the host, agent, and
environment, not by any single factor.

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Answer
False
Rationale: Epidemiologic triad is the classic model based
on the belief that health status is determined by the
interaction of the characteristics of the host, agent, and
environment, not by any single factor. Wheel of
causation de-emphasizes the agent as the sole cause of
disease while emphasizing the interplay of physical,
biological, and social environments.

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Epidemiologic Models
• Epidemiologic triad is the classic model based on the
belief that health status is determined by the interaction
of the characteristics of the host, agent, and
environment, not by any single factor.
• Wheel of causation de-emphasizes the agent as the sole
cause of disease while emphasizing the interplay of
physical, biological, and social environments.

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Question
Is the following sentence True or False?
Community assessments, using epidemiologic principles,
form the database that provides the evidence and
rationale for interventions.

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Answer
False
Rationale: Individual and community assessments, using
epidemiologic principles, form the database that provides
the evidence and rationale for interventions.

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Applying Epidemiologic Principles in
Practice
• Assessment of health needs and assets
– Individual assessment
– Community assessment
• Using assessment data for planning and implementing
interventions
• Promoting healthy lifestyles

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Behavioral Risk Factor Surveillance
System
• Promoting healthy lifestyles uses epidemiologic data such
as those found in the Behavioral Risk Factor Surveillance
System (BRFSS).
• The US publication Healthy People 2020 defines
measurable objectives to be achieved over the second
decade of the 21st century.
• Nurses in their care of individual and community clients
have the potential to link environmental exposure to
illness and disease.

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Applying Epidemiologic Principles in
Practice
• Preventing and controlling outbreaks
• Contributing to a safe and healthy environment
• Evaluating the effectiveness of health services