Nursing Community Health

1. EPIDEMIOLOGY- The Science of
Prevention
MONCY MATHEWS, MSN, RN

2. Chapter
Highlights
Defining epidemiology and communicable diseases
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
Wolter Kluwer

3. Why should you care?
Conceptualizing the community as a client is difficult for the individual-oriented nurse. Assessing
the health needs and assets of a community involves creating a comprehensive community
profile or database.
The individual nurse may be solely responsible for the assessment, but usually he or she
contributes to the assessment as a member of a team.
Epidemiologic statistical methods, such as calculation of rates, are used in this process

4. Focus care:
 Aggregates, communities
Focus care:
 Individuals & families

5. Community-orientednursing (ATIcommunitybook)
vs
Community-basednursing
Focus care:
 Aggregates, communities
Goal:
 Health promotion &
disease prevention
Nursing activities:
 Usually, indirect
 Can include direct care of
at-risk-individuals and
populations
Focus care:
 Individuals & families
Goal:
 Management of acute or
chronic conditions
Nursing activities:
 Direct
 Illness care: where
individuals, families and
groups live, work, and
attend

6. Epidemiology
Science of public health
◦ Common focus: the optimal health for all members of all communities, local
and global
Defined as:
◦ The study of the occurrence and distribution of health-related states or
events in specified populations, including the study of the determinants
influencing such states, and the application of this knowledge to control the
health problems

7. Defining
Epidemiology
Epidemic: an outbreak that occurs when there is an increased incidence
of a communicable disease beyond that which is normally found in the
population
Pandemic: When an epidemic occurs in multiple countries or continents
Rates- describe either the occurrence or the existence of a specific state
of health or illness:
Virulence: the degree of communicability
Leading causes of communicable disease deaths: Respiratory infection-
COVID-19, HIV/AIDS, diarrheal diseases, TB, malaria, and measles
Understanding epidemiology helps in prevention and treatment.
Nurses use epidemiological principles to provide health interventions to
targeted groups: Children, older adults, immunosuppressed clients,
Health care workers, international travelers

8. Nurses
◦ Use epidemiologic frameworks, methods , and data to better understand factors that
contribute to health and disease
◦ To develop health promotion and disease prevention intervention and measures;
◦ To identify the presence of infectious agents in individuals and groups
◦ To design, implement, and evaluate public health policies

9. Key terms in
this definition
reflect some of
the important
principles of
epidemiology.
Epidemiology is the study of the distribution and determinants (factors)
of health-related states or events in specified populations, and
the application of this study to the control of health problems.
Epidemiology is the study of health- related trends in population for the
purpose of disease prevention, health maintenance and health protection.
Epidemiology was originally focused exclusively on epidemics of communicable diseases
but was subsequently expanded to address endemic communicable diseases and non-
communicable infectious diseases and human effects of natural disasters, industrial
disasters, air pollution, nuclear accidents, and release of toxic chemicals.
Worldwide, communicable diseases are responsible for the deaths of millions of year.
Community health nurses must maintain knowledge of disease rates, modes of
transmission, incubation, early manifestations, periods of communicability, and how to
intervene to prevent them

10. Modes of transmissions
Vertical – through sperm,
placenta, vaginal contact
during birth, human milk
Horizontal – through contact
with a person or objects; the
air, contaminated body fluids,
food, and water, mosquitoes,
snails (vectors) Ex: Zika
Airborne: particles – through
air to susceptible host
•Measles, chicken pox, TB, Pertussis,
Influenza, SARS, COVID-19
Foodborne infection:
bacterial, viral, parasitic,
infection of food
•Norovirus, salmonellosis, Hep A,
Trichinosis, E. coli
Food intoxication: bacterial
growth, chemical
contamination, or disease-
producing substances
•Staphylococcus aureus, Clostridium
botulinum
Water borne – via a carrier
(mosquito or tick)
•Cholera, Typhoid fever, bacillary
dysentery, Giardia lamblia
Vector-borne: mosquito or
tick
•West Nile virus, Lyme disease, Rocky
Mountain spotted fever, Malaria

11. Modes of
transmissions
(cont.)
Direct Contact: transmission from infected host to
susceptible host via direct contact: Ex. Sexually transmitted
infection
HIV/AIDS
Chlamydia
Gonorrhea
Syphilis
HPV
genital herpes,
Hep B, C, D,
Infectious mononucleosis
Enterobiasis (pink worms)
Impetigo, lice, & scabies

12. Defense
Mechanisms
Herd Immunity: protection due to immunity of most community
members making exposure unlikely
Natural immunity: natural defense mechanisms of the body to resist
specific antigens or toxins
Acquired immunity develops through actual exposure to the infectious
agent
Active: Production of antibodies in response to infection or
immunization
Passive: Transfer of antibodies – (trans placental, transfusions of
immunoglobulins, plasma proteins, antitoxins)
Nurses can create community programs that monitor treatment
regimens.
Public nurses can identify cases, (assessment), develop programs, and
ensure follow-ups (tuberculin skin tests)
Health Care Goals: reduction in communicable diseases by increasing
safety practices by consumers: Immunizations, primary, secondary and
tertiary prevention.

13. Origin of
Epidemiology:
Epidemiology’s
roots are nearly
2,500 years old.
400 B.C. Hippocrates attempted to explain disease occurrence
from a rational rather than a supernatural viewpoint. In his essay
entitled “On Airs, Waters, and Places,” Hippocrates suggested
that environmental and host factors such as behaviors might
influence the development of disease.
1959, Thomas Moffet first description of living organisms cause
disease: lice, fleas, and scabies mice.
In 1662, he analyzed the weekly reports of births and deaths in London;
his analyses were the precursor of modern vital statistics. Graunt found
that more male infants were born than female infants and that more
men died than women. He also observed that infant mortality was high,
and he noted that seasonal variations occurred in deaths. He published
his observations and findings in Natural and Political Observations
Made Upon the Bills of Mortality.
1800s William Farr built upon Graunt’s work by systematically collecting
and analyzing Britain’s mortality statistics. Farr, considered the father of
modern vital statistics and surveillance, developed many of the basic
practices used today in vital statistics and disease classification. He
concentrated his efforts on collecting vital statistics, assembling and
evaluating those data, and reporting to responsible health authorities
and the general public.

14. Epidemiologist
1854s John Snow was conducting a series of investigations
in London that warrant his being considered the “father of
field epidemiology.” Twenty years before the development of
the microscope, Snow conducted studies of cholera
outbreaks both to discover the cause of disease and to
prevent its recurrence. (Spot Map)

15. Spot map of deaths fromcholera in Golden Square area, London,
1854 (redrawn fromoriginal)
Source: Snow J. Snow on cholera. London: Humphrey Milford: Oxford
University Press; 1936.

16. Epidemiologic
Models
Polar area diagram: to illustrate the extend of needless death in British
military hospitals during the Crimean War (1854-March 1855)
Epidemiologic triad: 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
The wheel of causation: De-emphasizes the agent as the sole cause of
disease, whereas it emphasizes the interplay of physical, biologic, and
social environments. Interaction between the host and environment, with
or without an identifiable agent, remains the major determinant of health
status in all epidemiologic models.
The web of causation: These can include both unpredicted and possibly
undesirable side effects. Public health professionals use web of causation
models such as this to design methods that interrupt the chain of events
that lead to adverse states of health. Strongly emphasizes the concept of
multiple causation while de-emphasizing the role of agents in explaining
illness.
Natural history of disease: This groundbreaking model integrated the
pathogenesis of an illness with primary, secondary, and tertiary
prevention measures
Wolter Kluwer

17. Florence Nightingale
polar area diagram
Illustrates the extent of needless deaths in British military hospitals during
the Crimean War, April 1854 to March 1855. The blue wedges measured
from the center of the circle represent area for area the deaths from
preventable zymotic diseases, the red wedges measured from the center
the deaths from wounds, and the black wedges measured from the center
the deaths from all other causes. The black lines across the red triangles in
September and November 1854 mark the boundaries of the deaths from all
other causes during those months. In October 1854, the black
area coincides with the red. The entire areas may be compared by following
the blue, the red, and the black lines enclosing them
[NIH Publication No. 89–3008, pp. 3–10]. Washington, DC: U.S. Department
of Health and Human Services, Public Health Service; Cohen, I. B. [1984].
Florence Nightingale. Scientific American, 250[3], 129.)

18. The epidemiologic Triad
Host: susceptible host – age, sex, genetics,
ethnicity, immunologic status, physiological state,
occupation
Agent: infectious agents – viruses, bacteria,
chemical agents – drugs, toxins, physical agents:
noise, temperature
Environment: Physical – geography, water/food
supply, presence of reservoirs/vectors
Social environment – access to health care, high
risk, working conditions, poverty

19. The Wheel of
Causation
These causal webs are more focused and
realistic, and they may be as intricate and
complex as needed. In this model, it is necessary
to identify all possible antecedent factors that
could influence the development or prevention of
a particular health condition.

20. The Web of
Causation
This example shows a classic web
of causation that identifies multiple
ways to reduce health problems, in
this case drug use and abuse in
adolescents.

21. Applying
Epidemiologic
Principles to
Practice
Epidemiologic process derived from problem solving
that provides a framework for gathering data about
health problems, analyzing the information,
generating diagnosis or hypothesis, planning for
resolution, implementing plan of action and
evaluating the results ( Same as nursing process).
The focus of epidemiologic process is on caring for
the population of the community as a whole.

23. Epidemiology
study
Epidemiology is a scientific discipline with sound methods of scientific inquiry at
its foundation.
Epidemiology is data-driven and relies on a systematic and unbiased approach to
the collection, analysis, and interpretation of data.
Basic epidemiologic methods tend to rely on careful observation and use of valid
comparison groups to assess whether what was observed, such as the number of
cases of disease in a particular area during a particular time period or the
frequency of an exposure among persons with disease, differs from what might
be expected.
However, epidemiology also draws on methods from other scientific fields,
including biostatistics and informatics, with biologic, economic, social, and
behavioral sciences.
In fact, epidemiology is often described as the basic science of public health
Epidemiology is not just a research activity but an integral component of public
health, providing the foundation for directing practical and appropriate public
health action based on this science and causal reasoning.
◦ Cdc.gov

24. Distribution
Epidemiology is concerned with the frequency and pattern of
health events in a population:
Frequency refers not only to the number of health events such
as the number of cases of meningitis or diabetes in a
population, but also to the relationship of that number to the
size of the population. The resulting rate allows epidemiologists
to compare disease occurrence across different populations.
Pattern refers to the occurrence of health-related events by
time, place, and person. Time patterns may be annual, seasonal,
weekly, daily, hourly, weekday versus weekend, or any other
breakdown of time that may influence disease or injury
occurrence.
Place patterns include geographic variation, urban/rural
differences, and location of work sites or schools. Personal
characteristics include demographic factors which may be
related to risk of illness, injury, or disability such as age, sex,
marital status, and socioeconomic status, as well as behaviors
and environmental exposures.

25. Determinants
Epidemiology is also used to search for determinants, which
are the causes and other factors that influence the
occurrence of disease and other health-related events.
Epidemiologists believe that illness does not occur randomly
in a population but happens only when the right
accumulation of risk factors or determinants exists in an
individual.
To search for these determinants, epidemiologists use
analytic epidemiology or epidemiologic studies to provide
the “Why” and “How” of such events.
They assess whether groups with different rates of disease
differ in their demographic characteristics, genetic or
immunologic make-up, behaviors, environmental exposures,
or other so-called potential risk factors. Ideally, the findings
provide sufficient evidence to direct prompt and effective
public health control and prevention measures.

26. Health-related
states or events
Epidemiology was originally focused exclusively on epidemics
of communicable diseases but was subsequently expanded
to address endemic communicable diseases and non-
communicable infectious diseases.
By the middle of the 20th Century, additional epidemiologic
methods had been developed and applied to chronic
diseases, injuries, birth defects, maternal-child health,
occupational health, and environmental health.
Then epidemiologists began to look at behaviors related to
health and well-being, such as amount of exercise and seat
belt use. Now, with the recent explosion in molecular
methods, epidemiologists can make important strides in
examining genetic markers of disease risk. Indeed, the term
health-related states or events may be seen as anything that
affects the well-being of a population.
Nonetheless, many epidemiologists still use the term
“disease” as shorthand for the wide range of health-related
states and events that are studied.

27. Specified
populations
Although epidemiologists and direct health-care providers
(clinicians) are both concerned with occurrence and control
of disease, they differ greatly in how they view “the patient.”
The clinician is concerned about the health of an
individual; the epidemiologist is concerned about the
collective health of the people in a community or
population. In other words, the clinician’s “patient” is the
individual; the epidemiologist’s “patient” is the community.
Therefore, the clinician and the epidemiologist have different
responsibilities when faced with a person with illness. For
example, when a patient with diarrheal disease presents,
both are interested in establishing the correct diagnosis.
However, while the clinician usually focuses on treating and
caring for the individual, the epidemiologist focuses on
identifying the exposure or source that caused the illness;
the number of other persons who may have been similarly
exposed; the potential for further spread in the community;
and interventions to prevent additional cases or
recurrences.

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

29. Applying Epidemiologic Principles in Practice
Preventing and
controlling outbreaks
1
Contributing to a
safe and healthy
environment
2
Evaluating the
effectiveness of
health services
3

30. COMMUNITY
ASSESSMENT
Assessing the health needs and assets of a community involves creating
a comprehensive community profile or database. The individual nurse
may be solely responsible for the assessment, but usually he or she
contributes to the assessment as a member of a team. Epidemiologic
statistical methods, such as calculation of rates, are used in this process
To obtain information about health beliefs, norms, values, goals,
perceived needs, and health practices, healthcare workers may use
focus groups, interviews or observation, or surveys
After epidemiologists collect the data, they synthesize and analyze the
information and generate a list of community health needs and assets.
Identifying patterns of disease, illness, and injuries detects trends that
form the rationale for program development. Critical thinking skills are
essential for the appropriate analysis of this information. Finally, it is
necessary to set goals and objectives to address high-priority
problems, implement and evaluate.
Although the term outbreak is often used synonymously with epidemic,
outbreaks are usually limited to a localized increase in the incidence of
the illness.
https://coursepoint.vitalsource.com

31. Determinants of Health Events
These are factors, exposures, behaviors,
contexts, and characteristics that determine
(or influence) the patterns (answers the how
and why); may be individual, relational,
social, communal, or environmental.

32. Epidemiological calculations
Epidemiology relies on statistical evidence to determine
the rate of spread and the proportion of people affected.
Evaluate effectiveness of disease prevention and health
promotion activities
To determine the extend to which goals were met
• Incidence and prevalence rates
• Mortality rates
• Attack rate
• Populations at risk

33. Rates
 Indices of the health of a community, region, or country
include comparisons of general mortality rates and maternal
infant rates.
 A variety of rates can be calculated according to need,
including incidence, prevalence, adjusted, and specific rates.
 Specific rates calculated by person, place, and time provide
the best description of a health condition.

34. Maternal & Infant
Mortality
 The infant mortality rate is the number of
infant deaths for every 1,000 live births.
 The infant mortality rate for U.S. in 2019 was
5.748 deaths per 1000 live births, a 1.15%
decline from 2018.
Infant mortality rate (IMR): Computed by dividing
the number of infant deaths in a calendar year by
the number of live births registered for that same
time period. IMR is the most widely used index
for measuring the risk of dying during the first
year of life.
https://www.cdc.gov/reproductivehealth/MaternalInfantHealth/InfantMortality.htm

35. EpidemiologY
“the study of the occurrence and distribution of health-related states or events
in specified populations, including the study of the determinants influencing
such states, and the application of this knowledge to control the health
problems.”
 Descriptive epidemiology seeks to describe the occurrence of a
disease in terms of person, place, and time.
 Analytic epidemiology focuses on investigation of causes and
associations.
 Ecologic approach is the broad consideration of many levels of
potential determinants.
 Distribution: determine who has the disease and where and when
it occurs.

36. Epidemiology - definition
Mortality rates are calculated for a specific groups
◦ Are informative only for fatal diseases and do not provide direct information about either the level of
existing disease in the population or the risk of contracting any particular disease.
Mortality rate:
◦ Refers to the relative death rate, or the sum of deaths in a given population at a given time.
Morbidity rate:
◦ Which is the relative incidence of disease in a population, the ratio of the number of sick individuals to
the total population is determined.

37. Incidence and Prevalence Rates
 Incidence rate—measure of the probability that people without a certain
condition will develop that condition over a period of time
 Prevalence rate—measures the number of people in a given population who
have an existing condition at a given point in time

38. Sensitivity and Specificity
 Sensitivity: the ability of a test to identify correctly people who
have the health problem under study
 Specificity: the ability of a test to correctly identify people who do
not have the health problem

39. Understanding and using rates
Incidence Rates p. 155
An incidence rate (also an occurrence or attack rate) is a
measure of the probability that people without a certain
condition will develop the condition over a period of time,
often a year.
ATI ebook (p.24) Number of new cases in the population at a specific
time/population total x 1,000 = ____ per 1,000

40. Understanding and using rates
Ati ebook: p. 24
Prevalence: # of existing cases in the population at a specific time / population total x 1,000 =
_______ per 1,000
Prevalence rates measure the number of people in a given population who have a
specific existing condition at a given point in time.
There are two types of prevalence rates.
Period prevalence indicates the existence of a condition during a period or an
interval of time.
Point prevalence refers to the existence of a condition at a specific point in time
and provides a picture of an existing situation for a group of people.

41. Mortality rates p.163/ATI p.24
Mortality rates indicate the probability of death from a specific cause; the
number of deaths from a specific disease is divided by the number of people in
the population at midyear and multiplied by 100,000.
• Crude mortality rates indicate the probability of death from any cause
among the entire population in a designated geographic area.
• Cause-specific (disease-specific) mortality rates indicate the probability of
death from a specific cause; the number of deaths from a specific disease is
divided by the number of people in the population at midyear and
multiplied by 1
• Case fatality rate, the number of people with a specific disease such as lung
cancer becomes the subgroup being studied out of the entire population in
a designated geographic area.
• Deaths at specific times across the lifespan (infant mortality ratio, age-
specific rate)

42. Basic Epidemiologic Methods
Use of existing data sources to study health outcomes and related factors and the use of
comparison groups to assess the association between exposures or characteristics and health
outcomes.
GIS (global positioning system)
GIS technology to display and analyze their data

43. Methods in Epidemiology
Sources of Data
◦ Census data, vital records, and surveillance data
◦ http://quickfacts.census.gov/qfd/states/48/48215.html
Hidalgo County, Texas
◦ Medical, health department, and insurance records
◦ Specific epidemiologic studies
CHARTing Health
Information for Texas

44. Specific studies
http://www.cdc.gov/
https://www.dshs.texas.gov/chs/brfss/
Texas Health Data
Center for Health Statistics

45. Descriptive Epidemiologic
Studies
 Provide information on the distribution of disease and health states according to personal
characteristics, geographic region, and time.
 This knowledge enables practitioners to target programs and allocate resources more
effectively and provides a basis for further study.
Secular trends
Point epidemic
Cyclical patterns
Event-related clusters

46. As Public Health Advocates
Nurses:
◦ Responsible for planning and implementing screening and prevention.
Planning and implementing programs targeted to the at-risk populations
Surveillance
◦ Involves the systematic collection, analysis, and interpretation of data
related to the occurrence of disease and the health status of a given
population
Active or passive systems

47. Applications of Epidemiology
in Nursing
Community-oriented epidemiology
Involves observation, data collection, consultation, and interpretation

48. Epidemiology of Wellness
Examine and uncover new health promotion practices and encourage them, we can focus on
wellness at the ideal primary level of prevention.
Four attributes that influence health:
1. Physical, social, and psychological environment
2. Lifestyle with its self-created risks
3. Human biology and genetic influences
4. The system of health care organization

49. Clinical decision-making
Identify a current health issue in your local community
1. Describe primary, secondary, and tertiary prevention interventions related to this health
issue.
2. How could nurses improve the effectiveness of their prevention activities related to this
health issues?

50. Summary
Epidemiology is not just “the study of” health in a population;
it also involves applying the knowledge gained by the studies
to community-based practice.
Epidemiology is the study (scientific, systematic, data-driven)
of the distribution (frequency, pattern) and determinants
(causes, risk factors) of health-related states and events (not
just diseases) in specified populations (patient is community,
individuals viewed collectively), and the application of (since
epidemiology is a discipline within public health) this study to
the control of health problems