This lecture introduces epidemiology by discussing its importance through achievements like smallpox eradication. It defines epidemiology as the study of health-related states in populations to prevent and control health problems. The lecture describes John Snow's contribution by showing cholera is spread through contaminated water before germ theory. It outlines the epidemiological approach as asking questions to make comparisons, and aims of epidemiology as describing disease distribution, identifying causes, and providing data for prevention planning.

1. EPIDEMIOLOGY
Lecture 1: Introduction

2. Lecture Objectives
By the end of this lecture, the student will be
able to:
1. Understand the importance of epidemiology
in medical sciences by knowing some of its
achievements.
2. Define epidemiology.
3. Describe the epidemiologic approach.
4. Enumerate the aims of epidemiology.

3. JohnSnow
Cholera

4. The contribution of John Snow
Cholera is spread by
contaminated water
(1850)
Vibrio cholerae
hadn’t yet been
discovered
Many years before
Louis Pasteur’s
“Germ theory of
disease” (1873)

5. How was Snow able to conclude that
Cholera is spread by contaminated
water?

8. Some important achievements in
Epidemiology

9. 1. Smallpox Eradication

10. 2. Methyl Mercury poisoning

11. 3. Rheumatic fever and RHD
Penicillin
Poverty
Poor housing
Overcrowding

12. 4. Tobacco use, Asbestos and Lung cancer

13. 5. The HIV/AIDS Epidemic

14. The definition of epidemiology
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
Observation, Surveillance, Hypothesis testing, Experiment
Time, Place, Person
Biological, Chemical, Social, Economic, Behavioural etc.
Entire populations, Groups of populations (Occupation, Residence,
Gender, Education etc.)

16. The Epidemiological Approach
1 Asking Questions
WHAT? WHERE? WHEN? WH0? HOW? WHY?
2 Making Comparisons

17. Aims of Epidemiology
• Describe distribution and magnitude of health
and disease problems in human populations.
• Identify etiological factors in disease
pathogenesis.
• Provide data essential to planning,
implementation and evaluation of services for
the prevention, control and treatment of
disease and to the setting up of priorities
among those services.

18. Sir Richard Doll
(1912-2005)