🧠Natural History of Disease
Definition: Disease ka complete course from exposure to outcome without intervention.
👉 Full journey of disease
🧩 Phases
Pre-pathogenesis
• No disease in host
• Only risk present
• Agent + Host + Environment
• No disease in host
• Only risk present
• Agent + Host + Environment
Pathogenesis
• Disease begins after entry
• Ends with outcome
• Disease begins after entry
• Ends with outcome
🧬 Stages
Subclinical
No symptoms
Incubation / latent
No symptoms
Incubation / latent
Clinical
Symptoms appear
Symptoms appear
Outcome
Recovery / Death
Recovery / Death
🌊 Clinical Horizon
👉 Point where symptoms appear
📊 Spectrum of Disease
No disease → Subclinical → Mild → Severe → Death