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Natural History of Disease & Levels of Prevention - Coggle Diagram
Natural History of Disease & Levels of Prevention
Four Stages:
Susceptibility Stage: Disease not present, but host factors (e.g., age, immunity) influence risk. Example: Healthcare workers susceptible to Hepatitis B.
Subclinical (Preclinical) Stage: Exposed but asymptomatic. Pathological changes occur. For infectious diseases, this is the incubation period (hours to years). For chronic diseases, it is the latency period (years to decades). Screening is most effective here.
Clinical Stage: Signs and symptoms appear. Diagnosis is usually made. Severity ranges from mild (common cold) to severe/fatal (rabies).
Resolution (Advanced) Stage: Outcome: recovery (spontaneous or via treatment), disability (e.g., blindness from meningitis), or death.
Natural History of Disease
Refers to the progression of a disease in an individual over time without treatment.
Involves interaction between host, agent, and environment.
Levels of Prevention (Applied to Natural History Stages)
Level
Primordial
Before risk factors emerge
Entire population
Policies to reduce tobacco advertising, building safe walking paths.
Primary
Before disease onset (Susceptibility stage)
Healthy individuals/groups
Health promotion (nutrition, exercise), specific protection (immunization, chemoprophylaxis).
Secondary
Early stage of disease (Subclinical/early Clinical)
Individuals with early disease
Screening (mammography, BP measurement), early diagnosis, prompt treatment to prevent complications.
Tertiary
After disease has caused disability (Resolution stage)
Individuals with established disease/disability
Rehabilitation: medical (artificial limb), psychological, social, occupational, vocational.
Timing
Target Population
Examples