Concept of Disease in Public Health

What is the primary focus of the natural history of disease?

What is the term for the varying signs, symptoms, and severity of the same disease in a population?

What is the term for the stage of disease where an individual is infected but shows no symptoms?

What is the term for the 'hidden' cases of disease that are not diagnosed or reported?

What is the primary reason for the varying degrees of disease severity in a population?

What is the stage of disease where an individual begins to show symptoms?

What is the primary implication of the iceberg phenomenon for public health?

What is the term for the stage of disease where an individual is recovering from an illness?

What is the primary focus of control measures in the context of the natural history of disease?

What is the term for the period of time between exposure to a disease-causing agent and the onset of symptoms?

Concept of Disease

A disease is a condition where body function is impaired, departing from a state of health, and altering the performance of vital functions.

Theories of Disease Causation

Supernatural theory of disease
Ecological theory
Germ theory: Microorganisms cause many known diseases (Pasteur, Henle, Koch)
Multifactorial causation theory: Agent, host, and environmental factors interact synergistically to cause disease

Epidemiologic Triad

Agent (pathogen): Biological, Nutrient, Chemical, Physical, Mechanical, or Genetic
Host (susceptible individual): Intrinsic (age, race, sex, socioeconomic status) and modifiable factors (behaviors)
Environment: Physical (geology, climate), Biologic (insects), and Socioeconomic (crowding, sanitation, health services)

Natural History of Disease

Refers to the progress of a disease process in an individual over time without intervention
Stages of disease:
- Pre-pathogenic phase or susceptibility stage
- Pathogenic phase:
  - Incubation period
  - Prodromal stage
  - Stage of overt disease
  - Stage of convalescence

Spectrum of Disease

The idea that an exposure can lead to varying signs, symptoms, and severity of the same disease in a population
Varying degrees of severity due to interactions of host, agent, and environmental factors
Disease forms:
- Acute
- Chronic/insidious
- Carrier

Iceberg Phenomenon

Cases of illness diagnosed by clinicians represent only the "tip of the iceberg"
Many additional cases may be too early to diagnose or remain asymptomatic
Risk of transmission by persons with in-apparent or undiagnosed infections

This quiz covers the concept of disease, theories of disease, epidemiologic triad, natural history of disease, and spectrum of disease. It is designed for students of the Faculty of Medicine at Merit University.