lec 1 introduction to epidemiology d.pdf

lecture 1 of epidemiology for medical laboratory student

1. Introduction to Epidemiology
Dr- Yaxya Kh.Ciisa
BSc , MSc
1

2. Introduction
Greek word:
▪Epi: Among
▪Demos: people
▪Logos: study
Epi + Demos + logos
•The word epidemiology has its roots in the study of what
befalls a population.

3. Definition
Epidemiology 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 control of health problems.

4. Cont…
A scientific discipline
Basic “core” science of public health.
For good reason:
Epidemiology is a quantitative discipline.
Epidemiology is a method of causal reasoning based on developing and
testing hypothesis
Tools of public health actions.

5. Cont..
Study: Concerned with
Surveillance, observation, hypothesis testing, analytic
research and experiments.

6. Cont…
Distribution is concerned with:
✓Frequency & pattern of health events in a
population.
✓Rate or risk of developing disease in the
population.

7. Cont…
Pattern refers to:
The occurrence of health related by:
Time, Place and person characteristics

8. Cont…
Time characteristics:
•Annual occurrence
•Seasonal occurrence
•Daily occurrence ( During epidemic )
•Hourly occurrence ( During epidemic )

9. Cont…
Place characteristics:
•Geographical variation
•Urban –rural differences
•Location of houses, worksites or schools.

10. Cont…
Personal characteristics:
•Age
•Race
•Sex
•Martial status
•SES
•Lifestyle behavior, occupation
•Environmental exposures

11. Descriptive epidemiology
This characterization of the distribution of health
related states or events in one broad aspect of
epemiologycalled descriptive epidemiology
What ?
Who ?
When ?
Where ?

12. Analytic epidemiology
Determinants
Epidemiologic methods are used as tools to
search for causes and other factors that influence
the occurrence of health related events-analytic
epidemiology
Why ?
How ?

13. Cont…
Health-related states or events include:
•Communicable diseases
•Non communicable diseases
•Injuries, birth defects
•Maternal-child health
•Occupational & environmental health
•Behaviors related to health ( exercise etc.)

14. Cont…
Specified population include:
•Those with identifiable characteristics, such as
occupational group.
•The epidemiologist is concerned about the collective
health of the people in a community or population.

15. History of epidemiology
Hippocrates ( 460BC): Environment & human
behaviors effects health.
John Graunt( 1662): Was one of the firs
demographers quantified births, deaths and
disease.

16. Cont…
Lind ( 1747 ):Scurvy could be treated with fresh fruit.
Was a Scottish physician. By conducting one of the first
ever clinical trials, he developed the theory that citrus
fruits cured scurvy.

17. Cont..
William Farr 1839 –Father of vital statistics
Examined effects of marital status , occupation, etcon
morbidity and mortality statistics
Ramazzini-1700
Italian physician –father of occupational health

18. Cholera ( 19
th
century)
•English anesthesiologist, John Snow 1845
•Father of modern epidemiology
John snow’s accomplishments:
▪Identified mode of transmission
▪Incubation times
▪Causes and effect
▪Clinical observations of cholera

19. Cont..
Doll & Hill 1950 : used a case control design to describe
and test the association between smoking and lung
cancer.
Frances at al 1950: huge formal field trial of the
poliomyelitis vaccine in school children.
Dawberet al 1955: used the cohort design to study risk
factors for cardiovascular disease in the Framingham
heart study.

20. Epidemiology versus clinical medicine
Epidemiology
•Unit of study is a defined
population or population at risk
•Concerned with sick as well as
healthy
•Investigator goes to the
community
•identify source of infection,
mode of spread, an Etiological
factor, future trend or
recommend control measures
Clinical medicine
•Unit of study is case
•Concerned with only sick
•Patient comes to doctor
•Seeks diagnosis, derives
prognosis, prescribes specific
treatment