Lect 1 Egidemiology

Epidemiology
Dr / Hanem Awad Mekhamier

Assistant Professor of Family & Community Health Nursing
2022- 2023
Introduction to Epidemiology
Learning Objectives:
After completion of this lecture, each student should be
able to:
•Describe basic terminology and concepts of

epidemiology.
•List purposes / Objective of epidemiology.
•List uses of epidemiology.

- The word epidemiology comes from the Greek words:-
• Epi = upon • Demos = people • Ology = science
• The science which deals with what falls upon people.
• Who gets disease and why?
• Epidemiologists study sick and healthy people to
determine the essential difference between those who get
disease and those who are saved.

Definition of Health
Health according to WHO as a state of
physical, mental, and social well being and
not just the absence of disease or disability.

Epidemiology key terms:
Epidemiology:is the branch of medicine

dealing with the incidence and
prevalence of disease in large
populations and with detection of the
source and cause of epidemics of
infectious disease.
Another definition
the study of the distribution and
determinants of health-related states or
events in specified populations and the
application of this study to prevent and
control of health problems.
Cluster:
It is group of cases in a specific time and place that
might be more than expected.
Rate:
Number of cases occurring during a specific period;
always dependent on the size of the population during
that period.
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.
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.
Determinants:
They are the causes and other factors that

influence the occurrence of disease and other
health-related events.
Health-related states or events:
It may be seen as anything that affects the well-

being of a population.
* Epidemiology was originally focused
exclusively on epidemics of
communicable diseases but was
subsequently expanded to address
endemic communicable diseases and
non-communicable infectious diseases.
Specified populations
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; But 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.
The objectives of epidemiology:
First:
1. To identify the etiology or cause of a disease and the
relevant risk factors that increases a person’s risk for a
disease.
2. To intervene to reduce morbidity and mortality from
the disease.
3. To know how the disease is transmitted from one person
to another or from a nonhuman reservoir to a human
population.
4. To develop a rational basis for prevention programs.
Cont.,
 Second, to determine the extent and burden of the

disease found in the community.
 Third: to study the natural history and prognosis of the

disease.
 Fourth: to evaluate both existing and newly developed

preventive and therapeutic measures and modes of
health care delivery.
Cont.,
Fifth: to provide the basis for

development of public policy related to
environmental problems, genetic issues,
and other considerations regarding
disease prevention and health
promotion.
Uses of Epidemiology:
1. To study the disease trend since past .
2. Assessing the community’s health and

community diagnosis; i.e., what are the major
health problems occurring in a community.
3. Establishing the history of a disease in a

population; e.g., identifying the periodicity of an
infectious disease.
4. Describing the natural history of disease in the individual;
e.g., natural history of HIV infection in the individual
(infection-acute syndrome-asymptomatic phase-clinical
disease-death).
5. Filling in the gaps in the natural history of the disease.
6. Describing the clinical picture of disease; i.e., who gets the
disease, who dies from the disease, and what the outcome of
the disease is.

7. Planning and evaluation of health services.
8. Determining and estimating the risk to an individual
risk; e.g., what factors increase the risk of heart disease,
automobile accidents, and violence.
9.Evaluating the prevention/intervention of programs;
e.g., vaccine and clinical trials.

10.Evaluation of a new therapy or a new
health measure.
11. Searching and investigating for the
cause of epidemics/diseases of unknown
etiology.

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Epidemiology

Dr / Hanem Awad Mekhamier

•Describe basic terminology and concepts of

•List purposes / Objective of epidemiology.

•List uses of epidemiology.

• Epi = upon • Demos = people • Ology = science

• The science which deals with what falls upon people.

• Who gets disease and why?

• Epidemiologists study sick and healthy people to

determine the essential difference between those who get

disease and those who are saved.

Health according to WHO as a state of

physical, mental, and social well being and

not just the absence of disease or disability.

Epidemiology:is the branch of medicine

It is group of cases in a specific time and place that

might be more than expected.

Number of cases occurring during a specific period;

always dependent on the size of the population during

Epidemiology is concerned with

the frequency and pattern of

health events in a population.

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

Refers to the occurrence of health-

related events by time, place, and

May be annual, seasonal, weekly, daily,

hourly, weekday versus weekend, or any

other breakdown of time that may

influence disease or injury occurrence.

Include geographic variation,

urban/rural differences, and

location of work sites or schools.

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

They are the causes and other factors that

Health-related states or events:

It may be seen as anything that affects the well-

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.

individual; But the epidemiologist is concerned about

the collective health of the people in a community or

 In other words, the clinician’s “patient” is the

individual; the epidemiologist’s “patient” is the

 Second, to determine the extent and burden of the

 Third: to study the natural history and prognosis of the

 Fourth: to evaluate both existing and newly developed

Fifth: to provide the basis for

2. Assessing the community’s health and

3. Establishing the history of a disease in a

e.g., natural history of HIV infection in the individual

(infection-acute syndrome-asymptomatic phase-clinical