Disease Pattern Terms

Aug 17, 2025

Overview

This lecture explains four key terms to describe patterns in the occurrence of diseases: sporadic, endemic, epidemic, and pandemic.

Sporadic Diseases

  • Sporadic diseases occur occasionally and irregularly, without a specific geographic pattern.
  • Examples include tetanus, rabies, and plague, which appear in small numbers and in random locations.

Endemic Diseases

  • Endemic diseases are constantly present within a specific population or region.
  • Examples include malaria and HIV infection in certain regions such as sub-Saharan Africa.

Epidemic Diseases

  • Epidemic diseases show a sudden and significant increase in cases in a particular area over a short period.
  • Epidemics can occur in small or large areas, such as a town or an entire country.
  • Flu season outbreaks are a common example of epidemics.

Pandemic Diseases

  • Pandemic diseases are epidemics that spread across multiple countries or worldwide.
  • The 1918 flu pandemic is a classic example, killing millions globally within a short time frame.

Key Terms & Definitions

  • Sporadic Disease — A disease that appears occasionally and irregularly with no geographic pattern.
  • Endemic Disease — A disease consistently present in a population or region.
  • Epidemic Disease — A disease characterized by a sudden increase in cases within a specific area.
  • Pandemic Disease — A worldwide epidemic affecting a large proportion of the global population.

Action Items / Next Steps

  • Review definitions and examples of each disease occurrence term.
  • Be prepared to identify or give examples of each term for future assessments.