Concepts of disease and causation
HEALTH
• Concepts of health
– 1. Biomedical concept
– 2. Ecological concept
– 3. Psychological concept
– 4. Holistic concept
• WHO definition of health:
– Health is a state of complete physical, mental and social
wellbeing and not merely an absence of a disease or
infirmity.
Concept of disease
• Define health
• Disease ?
– Departure from state of health, an alteration of the
human body interrupting the performance of vital
functions
Webster
– Condition of a body or some part or organ of the body in
which functions are disrupted
Oxford dictionary
– Ecological – maladjustment to environment
– Sociology – looking at disease from a society point of
view
Concept of disease
• Simplest defn: opposite of health
• But all are inadequate as they cannot specifically pin point
as to where the disease process started
• Disease has a spectrum ranging from in apparent infection
to severe manifestation to death
Some important concepts
• Disease
– Physiological or psychological dysfunction
• Illness
– Subjective state of person feeling unwell
• Sickness
– State of social dysfunction
Causation of a disease
Theories of disease causation
• Supernatural theory
• Theory of humors
• Concept of contagion
• Miasmatic theory of disease
• Theory of spontaneous generation
Germ theory of disease
Disease Agent  Man  Disease
Epidemiological Triad
ENVIRONMENT
AGENT
HOST
Triangle of Epidemiology
ENVIRONMENT
TIME
AGENT
HOST
Advanced Model Of
Epidemiological Triad
Causative factor
TIME
Groups
Environment
behaviour & culture
Web of causation
Web of causation
Web of causation
Web of causation
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