UNIT I INTORDUCTION TO EPIDEMIOLOGY.pdf

Introduction to Epidemiology
BURHAN UDDIN
Nursing Instructor
Post RN BSc.N, Dip-card, RN
BRITISH COLLEGE OF NURSING

OBJECTIVES
By the end of the unit, the learners will
be able to
 Define Epidemiology
 Explain introduction of Epidemiology
 Discuss the uses of Epidemiology
 Explain the scope of Epidemiology
2
Burhan Uddin, Karachi

Brain Storming
 Each individual likes different subject/s
 Agree / Disagree
 If Agree;
 Then, Share
 How many subjects have been taught in BSN
till last Semester?
 Name the subjects in BSN, Semester – VI
/ Semester - II
 Share, which subject/s is/ are mostly liked by
you?
Burhan Uddin, Karachi 3

Epidemiology
Buran Uddin, Karachi 4
 Epidemiology is the study of the
distribution and determinants of health-
related states or events (including
disease),
and
 the application of this study to the control of
diseases and other health problems.
(WHO 2017)

Epidemiology Defined
• “The study of epidemics”
• Greek roots
epi=upon (as in “epidermis”)
Demos=the people (as in demography)
ology=“to speak of”. “to study”
• Modern definition of epidemiology refer to
-Distributions in populations (statistical)
-Determinants
(pathophysiology, biology, chemistry, psychology)
-Control of health problems
(biological, social, economic, political, administrative,
legal)
5

Components of the definition
Study: Systematic collection, analysis and
interpretation of data.
Epidemiology involves collection, analysis and
interpretation of health related data.
Epidemiology is a science
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7

Components
2. Frequency: the number of items an event
occurs
Epidemiology studies the number of times a
disease occurs
It answers the question How many?
Epidemiology is quantitative science.
8

3. Distribution: Distribution of an event by
person, place and time.
Epidemiology studies distribution of disease
It answers the question who, where and
when
Epidemiology describes health events.
9
Components

4. Determinants: Factors the
presence/absence of which affect the
occurrence and level of an event
Epidemiology studies what determines
health events
It answers the question how and why?
Epidemiology analyzes health events.
10
Components

5. Disease & other health related events
Epidemiology is not only study of disease
The focus of Epidemiology are not only
patients
It studies all health related conditions
Epidemiology is a broader science
11
Components

6. Human population
Epidemiology diagnoses and treats
communities/populations
Clinical medicine diagnoses and treats
patients
Epidemiology is a basic science of public
health
12
Components

7. Application
Epidemiological studies have direct and
practical applications for prevention of
disease & promotion of health.
Epidemiology is science and practice
Epidemiology is an applied science
13
Components

What is public health
• Public health refers to all organized measures to
prevent disease, promote health and prolong life
among the population as a whole
-WHO
• Its activities aim to provide conditions in which
people can be healthy and focus on entire
populations, not on individual patients or
disease.
• Thus, public health is concerned with the total
system and not only the eradication of a
particular disease.
14
Components

Historical Context of
Epidemiology
15

EPIDEMIOLOGY TREE
ORIGIN
(HIPPOCRATIC TIMES ) 463 BC
DEVELOPMENT 1915 – till to date
GROWTH 1600-1905 AD
(GRAUNT TO FLETCHER)

History of Epidemiology
Seven land marks in the history of
Epidemiology
• Hippocrates(460BC): Environment &
human behaviors affects health
• John Graunt (1662): Quantified births,
deaths and diseases
• Lind (1747): Scurvy could be treated with
fresh fruits
17

• William Farr (1839): Established application
of vital statistics for the evaluation of health
problems
• John Snow (1854): Tested a hypothesis on
the origin of epidemic of cholera
• Alexander Louis (1872): Systematized
application of numerical thinking (quantitative
reasoning)
18

• Bradford Hill(1937): Suggested criteria
for establishing causation
Epidemiological thought emerged in 640 BC
Epidemiology flourished as a discipline in
1940s
19

HIPPOCRATES (400 BC): “On Airs, Waters, and
Places” –Hypothesized that disease might be
associated with the physical environment,
including seasonal variation in illness.
JOHN GRAUNT (1662): “Nature and Political
Observations Made Upon the Bills of
Mortality” – First to employ quantitative
methods in describing population vital
statistics.
JOHN SNOW (1850): Formulated natural
epidemiological experiment to test the
hypothesis that cholera was transmitted by
contaminated water.

HIPPOCRATES , THE FIRST EPIDEMIOLOGIST

Example
 John Snow, physician(1813-1858)
 Outbreaks of Cholera were common in London
during the 19th century
 But what was causing the cholera? The popular
theory at the time was that bad gases caused it
(‘miasma’ theory)
25

What Did He Do?
Analysis by place: he mapped
the cases – most were near
Broad Street
Anecdote: People had
complained that the water smelt
bad. Cases from further afield
had water delivered by cart
from Broad Street.
26

What Did He Do?
 Recorded deaths by water
supplier
 Conclusion: Risk of
infection is highest in
people using water
Southwark and Vauxhall
water company .
28

Public Health Action
He removed the handle from the Broad Street pump and the
number of infections fell.
30

The Early Days…John Snow & Broad
Street Pump
30

The Early Days…John Snow & Broad
Street Pump
31

1600AD JOHN GRAUNT LONDON BILLS OF MORTALITYANALYSIS
1747 JAMES LIND CITRUS FRUITS TO CURE SCURVY IN
SAILORS
1796 EDWARD JENNER TRIAL WITH COWPOX VACCINE
1880
W.H .FROST EXPLAINED INTERPLAY OF FACTORS
CAUSING EPIDEMICS
1889
WILLIAM FARR
ANALYSIS OF VITAL STATISTICS &EFFECTS
OF IMPRISONMENT IN PRISONERS
1849 JOHN SNOW
NATURAL EXPERIMENT ON LONDON CHOLERA
1881 FINLAY MOSQUITO BORNE NATURE OF YELLOW FEVER
1900 BRADFORD
HILL. A
CONCEPT OF RANDOMIZATION &SMOKING AND
LUNG CANCER EXPERIMENTS
GROWTH 17TH TO 19TH CENTURIES

20 TH CENTURY DEVELOPMENT
1905 Fletcher PARBOILED RICE FOR TREATING
BERIBERI IN LUNATICS
1915 Gold Berger & Wheeler INDUCED PELLAGRA BY DIETARY
MODIFICATIONS
1942 Kinsley & Hemphill OXYGEN THERAPY &
RETROLENTAL FIBROPLASIA
1946
Medical Research Council (UK) WHOOPING COUGH VACCINE
TRIAL
1948 Framingham Heart Study CORONARY HEART DISEASE
1952 Doll SMOKING & LUNG CANCER
1954 A.B. Hill SMOKING & LUNG CANCER
1955 Brown & Hill
LEUKEMIA DUE TO IRRADIATION
TREATMENT FOR ANKYLOSING
SPONDYLITIS
1971 Boston Hospital Study ADENOCARCINOMA OF VAGINA IN
YOUNG WOMEN
20th
cen-
tury
WHO CLOFIBRATE CLINICAL TRIAL,
OSLO STUDY, NORTH KARELIA PROJECT,
MRFIT(USA), STANFORD THREE
COMMUNITY STUDY, BETA BLOCKERS IN
MYOCARDIAL INFARCTION, ASPIRIN STUDY
TO REDUCE
CARDIOVASCULAR
MORTALITY
,

FEW 21ST CENTURY
DEVELOPMENTAL STUDIES
ANTENATAL FOLATE
SUPPLEMENTATION
TO REDUCE NEURAL
TUBE DEFECTS
BETA CAROTENE IN
DIET
TO PREVENT
CANCERS
ARSENIC STUDY IN HUMAN CANCERS
IN URANIUM WORKERS FOR LUNG CANCERS

EVOLUTIONARY PROCESS
IT HAS GROWN FROM
• PURE OBSERVATIONS &ADVICES FROM
HIPPOCRATES TO
• COUNTING OF CASES &ANALYSIS BY
GRAUNT & WILLIAM FARR
• NATURAL EXPERIMENTS BY JOHN SNOW
• TRUE EXPERIMENTS
BY LIND, JENNER, FLETCHER, DOLL & HILL &
OTHER EPIDEMIOLOGISTS IN THE LAST TWO
CENTURIES

Aims of Epidemiology
• To describe the distribution & magnitude
of health & disease problems in human
populations.
• To identify etiological factors/risk factors
in the pathogenesis of disease
• To provide the data essential to the
planning, implementation & evaluation of
services for the prevention, control and
treatment of diseases & to the setting up
of priorities among those services.
36

The ultimate purpose of Epidemiology is
prevention of diseases & promotion of
health.
How?
1. Elucidation of natural history of disease
2. Description of health status of population
3. Establishing determinants of disease
4. Evaluation of intervention effectiveness
37
Purpose/uses of Epidemiology

• Description of the health status of the
populations. It includes proportion with ill
health, changes over time, change with age etc.
• Evaluation of interventions.
• Planning health services, public policy and
programs.
38

• To study historically the rise and fall of
disease in the population
• Community diagnosis
• Planning and evaluation
• Evaluation of individual’s risks and
chances
• Syndrome identification
• Completing the natural history of disease
• Searching for cause and risk factor
39

Scope of Epidemiology
Originally, Epidemiology was concerned with
investigation & management of epidemics of
communicable diseases.
Lately, Epidemiology was extended to endemic
communicable and non-communicable
infectious diseases
Recently, Epidemiology can be applied to all
diseases and other health related events
42

• Disease Definition: characteristics or combination of
character that best discriminate disease from non
diseased
• Disease occurrence: the rate of development of new case
in population. The proportion of current disease within
population
• Disease causation: The risk factors for disease
development and their relative strength with respect to an
individual and population
• Disease outcome: the outcome following disease onset
and of the risk factors
• Disease management: the relative effectiveness of
proposed therapeutic interventions
• Disease prevention: the relative effectiveness of proposed
preventive strategies including screening
43
Scope of Epidemiology

Summarization
45
Who is going to summarize the session?

Any More …
46

UNIT I INTORDUCTION TO EPIDEMIOLOGY.pdf

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