Epidemiology is defined as the study of disease distribution and factors influencing distribution in human populations. The main aims of epidemiology are to identify causal factors of disease, describe the magnitude of health problems in populations, and provide data to plan, implement and evaluate disease prevention and treatment services. Epidemiological studies use observational and experimental methods like cohort and case-control studies to investigate disease occurrence and risk factors. Key uses of epidemiology include understanding disease occurrence and risks, identifying community health problems, planning health services, and evaluating new programs and techniques.

1. EPIDEMIOLOGY

2. DEFINITION
“epidemiology is the study of distribution of
disease or a physiological condition in human
population and of the factor that influence this
distribution.”(Lilien feld-1980)
“The study of the distribution and determinants of
health related status or events in specific population and
application of this study to the control of health
problems”.(John m. Last -1988)

3. AIM & OBJECTIVE
 To identify etiological factor in the pathogenesis of
disease.
 To describe the distribution and magnitude of health
and disease problem in human population.
 provide the data essential to the planning
implementation and evaluation of services for the
prevention control and treatment of disease and to the
setting up of priorities among those services.

4. Epidemiological investigation
 INVESTIGATION APPROACH
(a) Asking question &making observation.
(b)Making comparison.

5. INVESTIGATION PROCES
Identification of problem.
Identification of population.
Review of literature.
Designing of study.
 Collection of data.
Analysis and interpretation of data.
 Conclusion and Implication.

6. METHOD OF EPIDEMIOLOGICAL
STUDY
 Observational study.
A)descriptive study.
1.Cross sectional study.
2.Longitudinal study.
B) Analytical study.
1. case –control study.
2.cohort study.
 Experimental study
Randomized controlled trials

7. CASE CONTROL STUDY
 It involve two population- case and control.
 The unit is individual rather than the group.
 Focus is on a disease or some other health
problem that has already developed.
 It basically comparison studies.

8. BASIC STEPS OF CASE CONTROL
STUDY
SELECTION OF CASE AND CONTROL
MATCHING
MEASURMENT OF EXPOSURE
ANALYSIS AND INTERPRETATION

9. COHORT STUDY
 DEF:”A group of people who share a common
characteristic or experience within a defined time
period”
 INDICATION:
1.Good evidence of an association between
exposure and disease.
2.when exposure is rare, but the insides of disease
is high.
3.the study population can be minimized.

10. SURVEILLANCE
 DEF: The close vigilance on occurrence and
distribution of disease and health related problems,
population dynamic, community behavior and
environmental process resulting in increasing the risk
of ill health in the community.
 In individual level
 Community level.
 National level.
 International level.

11. USES OF EPIDEMIOLOGY
 Study the occurrence and distribution of diseases in a
community.
 Identify the determinants of disease .
 Diagnosis the health status of the community by
identifying health problems on the basis of morbidity and
mortality pattern.
 Estimate the risk i.e.. Statistical probability of disease .
 Plan effective need based health care services on the basis
of epidemiological information .
 Determine the effectiveness of health care services planned
and implemented on the basis of predetermined criteria
regarding its relevance ,effectiveness , efficiency , and
impact on community health.

12. Continued……….
 Determine the usefulness and effectiveness of new /
innovative techniques measured and programs etc.
before they used widely.
 Complete the clinical picture of chronic disease and
slow growing disease .
 Identify the syndrome by describing the distribution
and association of clinical phenomenon .