1. Introduction to Epidemiology
Bill Jenkins, Ph.D.
Maurice Jeter, B.S.
Morehouse College
Spring 2004

2. Introduction to Epidemiology
Definition: The study of distributions and determinants of diseases and conditions in human populations.
epi- that which comes upon
demi- people
ology- the study of

3. Introduction to Epidemiology
Three major characteristics of the science of Epidemiology
Biomedical
Quantitative
Population-Based

4. Introduction to Epidemiology
Science
The systematic collection, organization and utilization of knowledge
Purpose: To predict

5. Introduction to Epidemiology
“…shall I tell you what knowledge is? When you know a thing, to know it, and when you do not know a thing to recognize that you do not know it. That is knowledge.”
-Confucius

6. Introduction to Epidemiology
Statistics
The systematic collection, organization, analysis, and presentation of data.

7. Introduction to Epidemiology
Health
-Absence of illness and death
-A complete state of physical, mental, and social well-being
-Maximization of human potential

8. Introduction to Epidemiology
Epidemiology is a blending of many sciences:
As a MEDICAL science it provides understanding on the etiology and treatment of disease
As a MATHEMATICAL science it provides information on quantitative applications to health problems
As a SOCIAL science it provides understanding on the social factors affecting disease and the utilization of health services
As a POLITICAL science it provides information on the more effective means of allocating public support for health needs

9. Introduction to Epidemiology
Role of the Epidemiologist
Case finding – Public Health Advisors
Outbreak investigations – Epi Intelligence Officers (EIS)
Clinical research – Clinical Epidemiologists
Methodological research and consultation – Academic Epidemiologists
Etiological investigations – Senior Epidemiologists

10. Introduction to Epidemiology
Trends in Epidemiology
New developments in analytical techniques
Consideration of social factors in disease causation
Acceptance of multi-factorial causation
Increasing specification of disease

11. Introduction to Epidemiology
Q&A
Which of the following questions would be answered by an epidemiology study?
Which has a stronger affinity for hemoglobin: oxygen or carbon monoxide?
Does regular exercise reduce the chances of coronary heart disease among middle aged men?

12. Health Transitions
Life Expectancy
(Years)
Information Age
Life Expectancy: 67 yrs
Causes of Death: Infectious Diseases,
Strokes, Cancers, Other Chronic Diseases
Types of Diseases: Infectious Diseases and
Chronic Diseases
Major Social Forces: Computers 67
1980
Industrial Age 1100A.D
Life Expectancy: 47 yrs
Causes of Death: Infectious Diseases,
Injuries, Sanitation
Types of Diseases: Early Onset of
Chronic Diseases
Major Social Forces: Industrial Work
1950 57
1850 47
Scientific Age
Life Expectancy: 57 yrs
Causes of Death: Infectious Diseases
Types of Diseases: Infectious
Major Social Forces: 1st medicines were
being tested 37
Hunter Gather Period 90,000-6,000 B.C.
Life Expectancy: 17 yrs
Causes of Death: Infectious Diseases,
Animal Attacks, Starvation, Injuries
Types of Diseases: Starvation
Major Social Forces: Obtaining Food
11,000
Agriculture Age 6,000 B.C A.D.
Life Expectancy: 37 yrs
Causes of Death: Plague, Famine, Hunger
Types of Diseases: Plague (sanitation)
Major Social Forces: 1st Cities and Urbanization 17
90,000
6,000
B.C
A.D
Time Period

13. History of Epidemiology
Imhotep (3000 BC)
Imhotep was a physician, mathematician, and statesman.
The principle cause of disease in his time was believed to be an evil spirit which entered the body through the mouth, nose or ears. Its virulence was dependent on the times and seasons.
Public health programs of the period included regular clothes cleaning, use of antiseptics such as alcohol, and mosquito control.

14. History of Epidemiology
Hippocrates (500 BC)
Hippocrates (the greek father of Medicine) in his thesis: "On Airs, Waters, and Places" gives specific considerations to the patterns of disease with respect to these factors.
He suggested that the cause of disease was disturbances in constitution due to such factors as place, water, climate, nutrition, and housing.

15. History of Epidemiology
Graunt: 1600 AD
John Graunt published his: “Natural and Political Observations on the Bills of Mortality" in which he described the impact of the plague on the population of London.
This work is considered to be the founding work for both biostatistics and epidemiology. He suggested that data should be summarized and analyzed to determine the cause and patterns of disease. In this effort he was also the first to suggest the use of life table analysis in estimating the impact of mortality.

16. History of Epidemiology
Farr: (1850 AD)
A Physician and Statistician from
He observed patterns of mortality among various communities, occupations, seasons and ethnic populations. He is the first to make use of what we consider the basic tool of epidemiology, comparison among groups differing in the presence of an etiologic factor.
Farr established the first annual collection and analysis of health data.

17. History of Epidemiology
Snow:(1850 AD)
Used the techniques of epidemiology to establish that fact that fecal contamination was an etiologic factor of cholera in 1855 and that the spread of the disease could be minimized by stopping the use of water from the Southwark and Vauxhall water company, which took water from the polluted Thames River.

18. History of Epidemiology
Cholera Mortality by Water Districts. London, 1854.
Water District
Population
Deaths
Southwark & Vauxhall
167,654
192
Remainder of London
1,315,781
182

19. History of Epidemiology
Cholera Mortality by Water Districts. London, 1854.
Water District
Population
Deaths
Deaths/100,000
Southwark & Vauxhall
167,654
192
114
Remainder of London
1,315,781
182 16

20. History of Epidemiology
Goldberger: (1900 AD)
In about 1904 Goldberger began studying the development of pellagra among mill workers in Greenville, South Carolina.
He observed that green vegetables were associated with low incidence and recommended its consumption throughout the year. Later, the specific cause was found to be lack of niacin an element of vitamin B, resulting in its present-day addition to milk.

21. History of Epidemiology
Doll: (1940 AD)
Beginning in 1947 Richard Doll and Austin Bradford Hill began studying the increasing incidence of lung cancer in England.
They suspected the increased use of cigarettes was the cause. A retrospective study of smoking habits among lung cancer patients and other patients was initiated, and a small association was found between smoking and lung cancer.

22. History of Epidemiology
Smoking Habits Among Cancer and Other Patients. London, 1947
Lung Cancer
Cigarette Smoker Yes No
Yes No
Total
% who smoked 97% 92%
Retrospective study of smoking habits and lung cancer
688
650 21 59

23. History of Epidemiology
…Doll and Hill then initiated a prospective study and found a strong, consistent dose/response association between smoking and lung cancer . . .
Lung Cancer Mortality per 100,000 Population/Year Stratified by Smoking Status. London, 1951
Current Smoker
104
Former Smoker 43
Non-Smoker 10