Crash Course: Public Health - Epidemiology

Introduction

• In 2014, Ebola virus outbreak in Guinea, West Africa.
  • Over 11,000 deaths in two years.
• Epidemics: More people than usual in a group develop an illness.
  • Example: Near-sightedness in school-aged children in China, Singapore, South Korea (2019).

What is Epidemiology?

• Study of disease patterns and health conditions within populations.
• Origin: Greek words 'epi', 'demos', and 'logos'.
  • Means "upon people study".
• Focuses on: Who, what diseases, where, when.
• Historical focus on infectious diseases.
• Modern focus includes non-communicable diseases, environmental factors, health impacts of natural disasters.

Epidemiological Studies

• Aim: Understand causes and control diseases.
• Two main types:
  1. Experimental Studies
     • Participants exposed to interventions to see effects.
     • Compare with control group.
     • Positive interventions are ethical; negative are not.
  2. Observational Studies
     • Observe populations already exposed to a treatment/risk.
     • Example: British Doctor's Study (smoking and lung cancer).

Data Interpretation

• Correlation vs. Causation: Not all correlations imply causation (e.g., cheese consumption and bed sheet deaths).
• Bradford Hill Criteria
  • Nine principles for causal relationships.
• Mathematical Models
  • Identify relevant variables.
  • Example: Rothman Causal Pie.

Rothman Causal Pie

• Model to explain risk factors contributing to disease.
• Component Causes: Different risk factors.
  • Sufficient Cause: Complete pie leads to health condition.
  • Example: Tuberculosis
    • Necessary condition: Exposure to Mycobacterium tuberculosis.
    • Other factors: Overcrowding, poor ventilation, weakened immune system.

Conclusion

• Epidemiology helps understand and control health outcomes in a complex world.
• Future focus: Health systems.
• Produced by Complexly in partnership with the American Public Health Association.