Epidemiology

1. EPIDEMIOLOGY
INTRODUCTION: HISTORICAL ASPECTS AND EVOLUTION OF
EPIDEMIOLOGY, DEFINITION AND CONCEPT IN EPIDEMIOLOGY

2. 1. INTRODUCTION & DEFINITION

4. KEYWORD
• STUDY: EPIDEMIOLOGY IS A SCIENTIFIC DISCIPLINE WITH SOUND METHODS OF SCIENTIFIC INQUIRY AT ITS
FOUNDATION.
• 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
 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
• DETERMINANT: EPIDEMIOLOGY IS ALSO USED TO SEARCH FOR DETERMINANTS, WHICH ARE THE CAUSES AND
OTHER FACTORS THAT INFLUENCE THE OCCURRENCE OF DISEASE AND OTHER HEALTH-RELATED EVENTS
• HEALTH RELATED STATE OR EVENT: EPIDEMIOLOGY WAS ORIGINALLY FOCUSED EXCLUSIVELY ON EPIDEMICS OF
COMMUNICABLE DISEASES3 BUT WAS SUBSEQUENTLY EXPANDED TO ADDRESS ENDEMIC COMMUNICABLE DISEASES
AND NON-COMMUNICABLE INFECTIOUS DISEASES
• SPECIFIC POPULATION: ALTHOUGH 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.”
• APPLICATION: EPIDEMIOLOGY IS NOT JUST “THE STUDY OF” HEALTH IN A POPULATION; IT ALSO INVOLVES APPLYING
THE KNOWLEDGE GAINED BY THE STUDIES TO COMMUNITY-BASED PRACTICE.

5. 2. HISTORICAL ASPECTS AND
EVOLUTION OF EPIDEMIOLOGY

6. HISTORICAL EVOLUTION OF EPIDEMIOLOGY

9. 3. USES OF EPIDEMIOLOGY

10. USES OF EPIDEMIOLOGY
EPIDEMIOLOGY AND THE
INFORMATION GENERATED BY
EPIDEMIOLOGIC METHODS HAVE BEEN
USED IN MANY WAYS. SOME COMMON
USES ARE DESCRIBED BELOW.
• ASSESSING THE COMMUNITY’S
HEALTH
• MAKING INDIVIDUAL DECISIONS
• COMPLETING THE CLINICAL PICTURE
• SEARCHING FOR CAUSES

11. 4. CONCEPT OF DISEASE OCCURRENCE
&
EPIDEMIOLOGY DISEASE OCCURRENCE

19. 5. DISEASE TRANSMISSION [CHAIN OF
INFECTION] & MODE OF
TRANSMISSION

26. 6. NATURAL HISTORY OF DISEASE

30. 7. APPROACHES IN EPIDEMIOLOGY

33. For example, with a standard case
definition, health officials could
compare the number of cases of
listeriosis that occurred in Forsyth
County, North Carolina in 2000 with
the number that occurred there in
1999. Or they could compare the rate
of listeriosis in Forsyth County in
2000 with the national rate in that
same year. When everyone uses the
same standard case definition and a
difference is observed, the difference
is likely to be real rather than the
result of variation in how cases are
classified.

36. 8. DESCRIPTIVE EPIDEMIOLOGY

46. 9. ANALYTICAL EPIDEMIOLOGY