Epidemiology is the scientific study of disease distribution and determinants in human populations, aiming to understand health problems and identify risk factors. It informs public health strategies and clinical medicine, emphasizing community health assessment, disease prevention, and treatment evaluation. Key theories in epidemiology include germ theory, multiplication theory, and web-causation theory, which focus on the interaction of agents, hosts, and environments.

1. Basic Concept of Epidemiology
Presented by Rubi Sinha Mahapatra
Future School of Hospital Management
Masters in Hospital Administration (MHA)
1st Year
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2. What is epidemiology?
Epidemiology is derived from the Greek word epidemic:
 Epi - Among, upon
 Demose - Study population or people
 Logos - Scientific study
“It is the scientific study of the disease in human
population.”
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3. Epidemiology Definition:
“The study of distribution and determinants of health related states or
events in specified population and the application of the study to the
prevention and control of health problems.”
(By J.M.Last, 1988)
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4. Aims & Objectives of Epidemiology:
 Understand the distribution and magnitude of health problems in
human population
 Identify etiological risk factors in the pathogenesis of diseases
 Provide insights to the planning, implementation and evaluation of
services for the prevention, control and treatment of diseases
 Prioritization of services
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5. Application of Epidemiology in Public Health:
 Prevention of diseases and promoting health
 Community health assessment (Community Diagnosis) and priority
setting
 Improving prognosis and treatment of clinical diseases
 Evaluation of health interventions and programmes
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6. Theory of Epidemiology:
There are thee kinds of theories:
1. Germ theory : Propagated by the French Bacteriologist Louis Pastur in the
year 1873. According to this theory , agent factors, host factors & environment
lead to etiology (risk) disease.
2. Multiplication theory: This theory is not a “single cause idea” rather
depends upon social, economic, cultural, genetic, and psychological factors.
3. Web-causation theory: Complex interaction of factors results in disease
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7. Epidemiological Triad:
Agent:
Biolotgical, nutrient, physical,
chemical, social, mechanical
Host:
Man and Animal
Environment:
Physical , biological, psychological
Interaction between agent,
host & environment
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8. Web Causation Theory:
Myocardial
infraction
Changes in
lifestyle
Stress
Ageing
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9. Epidemiology and Public Health:
 Public health refers to collective actions to improve population health.
 Epidemiology is one of the tools for improving public health,in used in
several ways.
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10. Epidemiology and Clinical Medicine:
 In Clinical Medicine the unit of study is a ‘case’ but in the
Epidemiology the unit of study is ‘defined population’ or ‘population
risk’.
 In Clinical Medicine ,the physician seeks to diagnosis for which he
derives prognosis and prescribes specific treatment.
 In Clinical Medicine patient comes to the doctor.
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11. Thank You 
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