Microbiology
Textbooks
Boundless Microbiology
Epidemiology
Pathogen Identification
Microbiology Textbooks Boundless Microbiology Epidemiology Pathogen Identification
Microbiology Textbooks Boundless Microbiology Epidemiology
Microbiology Textbooks Boundless Microbiology
Microbiology Textbooks
Microbiology
Concept Version 6
Created by Boundless

Occurrence of a Disease

An occurrence of disease greater than would be expected at a particular time and place is called an outbreak.

Learning Objective

  • Recognize the steps taken by epidemiologists when investigating disease outbreaks


Key Points

    • Outbreaks may also refer to endemics that affect a particular place or group, epidemics that affect a region in a country or a group of countries, or pandemics that describe global disease outbreaks.
    • The epidemiology profession has developed a number of widely accepted steps to investigate a disease occurrence.
    • Outbreak patterns, which can be useful in identifying the transmission method or source, and predicting the future rate of infection include common source, continuous source, point source, and propagated source.
    • Outbreaks can be behavioral risk related (e.g., sexually transmitted diseases, increased risk due to malnutrition) or zoonotic (e.g. the infectious agent is endemic to an animal population).

Terms

  • pandemic

    A disease that hits a wide geographical area and affects a large proportion of the population.

  • epidemic

    A widespread disease that affects many individuals in a population.

  • outbreak

    A term used in epidemiology to describe an occurrence of disease greater than would otherwise be expected at a particular time and place.


Full Text

Occurrence of a Disease

Outbreak is a term used in epidemiology to describe an occurrence of disease greater than would otherwise be expected at a particular time and place. It may affect a small and localized group or impact thousands of people across an entire continent. Two linked cases of a rare infectious disease may be sufficient to constitute an outbreak. Outbreaks may also refer to endemics that affect a particular place or group, epidemics that affect a region in a country or a group of countries, and pandemics that describe global disease outbreaks .

1918 Flu Victims

With masks over their faces, members of the American Red Cross remove a victim of the Spanish Flu from a house at Etzel and Page Avenues, St. Louis, Missouri.

The epidemiology profession has developed a number of widely accepted steps when investigating disease outbreaks. As described by the Centers for Disease Control and Prevention, these include the following:

  1. Verify the diagnosis related to the outbreak.
  2. Identify the existence of the outbreak (if the group of ill persons is normal for the time of year, geographic area, etc. ).
  3. Create a case definition to define who/what is included as a case.
  4. Map the spread of the outbreak.
  5. Develop a hypothesis (if there appears to be a cause for the outbreak).
  6. Study hypothesis (collect data and perform analysis).
  7. Refine hypothesis and carry out further study.
  8. Develop and implement control and prevention systems.
  9. Release findings to greater communities.

There are several outbreak patterns that can be useful in identifying the transmission method or source and predicting the future rate of infection.

  1. Common source – All victims acquire the infection from the same source (e.g. a contaminated water supply).
  2. Continuous source – Common source outbreak where the exposure occurs over multiple incubation periods.
  3. Point source – Common source outbreak where the exposure occurs in less than one incubation period.
  4. Propagated – Transmission occurs from person to person.

Each has a distinctive epidemic curve, or histogram of case infections and deaths.

Outbreaks can also be:

  1. Behavioral risk related (e.g. sexually transmitted diseases, increased risk due to malnutrition)
  2. Zoonotic – The infectious agent is endemic to an animal population.
[ edit ]
Edit this content
Prev Concept
Exceptions to Koch's Postulates
Disease Severity and Duration
Next Concept
Subjects
  • Accounting
  • Algebra
  • Art History
  • Biology
  • Business
  • Calculus
  • Chemistry
  • Communications
  • Economics
  • Finance
  • Management
  • Marketing
  • Microbiology
  • Physics
  • Physiology
  • Political Science
  • Psychology
  • Sociology
  • Statistics
  • U.S. History
  • World History
  • Writing

Except where noted, content and user contributions on this site are licensed under CC BY-SA 4.0 with attribution required.