Chapter 1
Introduction and descriptive epidemiology :
history and uses of epidemiology
Learning Objectives:
At the end of this unit the student is expected to:
• describe the key aspects of epidemiology
• Discuss the uses of Epidemiology
• Identify the basic study designs used in epidemiology
• recognize the role of epidemiology in society and link
epidemiology to nursing practice.
.
History of Epidemiology
• John Snow.
• In 1849, John Snow, an
English
physician,
formulated and tested a
hypothesis concerning
the origin of an
epidemic of cholera in
London..
John Snow’s Map
http://scienceblogs.com/significantfigures/ind
ex.php/2013/03/11/200-years-of-dr-johnsnow-a-significant-figure-in-the-world-ofwater/
History of Epidemiology
• Between 1849 and 1854, the Lambeth
Company changed its source to an area of the
Thames where the water was "quite free from
the sewage of London." The rates of cholera
declined in those areas of the city supplied by
the Lambeth Company, while there was no
change in those areas receiving water from
the Southwark and Vauxhall Company.
• Finally, Snow concluded that the source of
cholera outbreak was contaminated water.
What is epidemiology
• Epidemiology is the study of how disease is
distributed in populations and the factors that
influence or determine this distribution.
• Epidemiology is about the understanding of
disease development and the methods used to
uncover the etiology, progression, and treatment
of the disease.
• It is the study of patterns of disease, risk
behaviors and protective factors in human
populations.
Definition
• Epidemiology as defined by Last is “the study
of the distribution and determinants of
health-related states or events in specified
populations, and the application of this study
to the prevention and control of health
problems”
Definition of epidemiology
Study
• includes:
surveillance,
observation,
hypothesis testing, analytic research and
experiments.
Distribution
• refers to analysis of: times, persons, places
and classes of people affected.
Determinants
• include factors that influence health:
biological, chemical, physical, social,
cultural, economic, genetic and behavioral.
Healthrelated states
and events
• refer to: diseases, causes of death, behaviors
such as use of tobacco, positive health states,
reactions to preventive regimes and
provision and use of health services.
Specified
populations
• include
those
with
identifiable
characteristics, such as occupational groups.
Application
to prevention
and control
• the aims of public health—to promote,
protect, and restore health.
THINK-PAIR-SHARE ACTIVITY
If you were a nurse in Snow’s time, list what
hypotheses you might generate about cholera
transmission from these observations.
Uses of Epidemiology
• To make a community diagnosis. Epidemiology
helps to identify and describe health problems
in a community (for example, the prevalence
of anemia, or the nutrition status of children).
• To monitor continuously over a period of time
the change of health in a community. (for
example, the effect of a vaccination program,
health
education,
nutritional
supplementation).
Uses of Epidemiology
• To practice surveillance for a specific disease in
order to be able to act quickly and so cut short
any outbreak (example cholera)
• To investigate an outbreak of a communicable
disease, analyze the reasons for it, plan a feasible
remedy and carry it out, and monitor the effects
of the remedy on the outbreak.
• To plan effective health services. Effective
services, interventions and remedies all depend
on accurate community data.
Objectives of Epidemiology
1. Identify disease etiology
2. Determine the burden of
disease
3. Study the natural history
of disease
4. Evaluate preventive and
therapeutic measures
5. Provide foundation for
public policy
Descriptive vs. Analytical Epidemiology
Descriptive Epidemiology
Includes activities related to characterizing the
distribution of diseases within a population
Analytical Epidemiology
Concerns activities related to identifying possible
causes for the occurrence of diseases
Disease distribution also known as:
(Descriptive epidemiology)
• Disease distribution is considered in terms of
Persons, time and place (Who, when and
where).
Person
Place
Time
Persons
• Persons who are affected by disease in terms
of age, sex, race, occupation etc.
• The common characteristics relating to those
persons affected by disease.
Time
• Time relates to when the diseases is most
likely to increase e.g. an epidemic, endemic,
seasonal, cyclic etc .
Place
• Place refer to the
geographical
distribution of a
diseases and the
common characteristics
that are favorable for
that diseases in the
given locality.
• Some diseases are
localized, regional,
pandemic etc
Disease determinant factors
• also knows as “Analytic epidemiology”
• it include the Agent, host and environment
Epidemiology and prevention
Epidemiology and clinical practice
• Epidemiology is critical not only to public health but also to
clinical practice. The practice of medicine is dependent on
population data.
• Example, if a physician hears an apical systolic murmur, how
does he or she know that it represents mitral regurgitation?
Where did this knowledge originate? The diagnosis is based
on correlation of the clinical findings (such as the auscultatory
findings—sounds heard using a stethoscope) with the findings
of surgical pathology or autopsy and with the results of
catheterization or angiography studies in a large group of
patients.
Link epidemiology to nursing practice
Epidemiological studies can potentially offer
considerable benefits to the way nurses
incorporate health-related practices into their
professional role. Epidemiological studies also
offers a valuable opportunity for the nursing
profession to become more active in helping
to determine health policy issues.
• How does epidemiology relate to nursing?
• Why is epidemiology important in the nursing
profession?
• Can nurses be epidemiologists?
Summary
• Epidemiology is the study of the distribution and
determinants of health-related states in
populations
• Epidemiology is an invaluable tool for providing a
rational basis on which effective prevention
programs can be planned and implemented.
REFERENCES
Celentano, D., Szklo, M. and Gordis, L. (2019). Gordis
epidemiology
Section I :
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