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 upon 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 epidemics, which affect a region in a country or a group of countries, or pandemics, which describe global disease outbreaks.


Outbreak investigation

When investigating disease outbreaks, the epidemiology profession has developed a number of widely accepted steps. As described by the Centers for Disease Control and Prevention, these include the following:[1]

  • Verify the diagnosis related to the outbreak
  • Identify the existence of the outbreak (Is the group of ill persons normal for the time of year, geographic area, etc.?)
  • Create a case definition to define who/what is included as a case
  • Map the spread of the outbreak using Information technology as diagnosis is reported to insurance
  • Develop a hypothesis (What appears to be causing the outbreak?)
  • Study hypothesis (collect data and perform analysis)
  • Refine hypothesis and carry out further study
  • Develop and implement control and prevention systems
  • Release findings to greater communities


There are several outbreak patterns, which can be useful in identifying the transmission method or source, and predicting the future rate of infection. Each has a distinctive epidemic curve, or histogram of case infections and deaths.[2]

  • Common source – All victims acquire the infection from the same source (e.g. a contaminated water supply).[3]
    • Continuous source – Common source outbreak where the exposure occurs over multiple incubation periods
    • Point source – Common source outbreak where the exposure occurs in less than one incubation period[4]
  • Propagated – Transmission occurs from person to person.[5]

Outbreaks can also be:

  • Zoonotic – The infectious agent is endemic to an animal population.

Patterns of occurrence are:

  • Endemic – a communicable disease, such as influenza, measles, mumps, pneumonia, colds, small pox, which is characteristic of a particular place, or among a particular group, or area of interest or activity
  • Epidemic – when this disease is found to infect a significantly larger number of people at the same time than is common at that time, and among that population, and may spread through one or several communities.
  • Pandemic – occurs when an epidemic spreads worldwide.

Outbreak legislation

Outbreak legislation is still in its infancy and not many countries have had a direct and complete set of the provisions.[7][8] However, some countries do manage the outbreaks using relevant acts, such as public health law.[9]


  1. ^ Steps of an Outbreak Investigation, EXCITE | Epidemiology in the Classroom | Outbreak Steps
  2. ^ [1][dead link]
  3. ^ Glossary of Epidemiology Terms, Cdc.gov (2007-04-25). Retrieved on 2010-11-25.
  4. ^ Glossary of Epidemiology Terms. Cdc.gov (2007-04-25). Retrieved on 2010-11-25.
  5. ^ Glossary of Epidemiology Terms. Cdc.gov (2007-04-25). Retrieved on 2010-11-25.
  6. ^ [2][dead link]
  7. ^ "Bioterrorism Training and Curriculum Development Program". http://library.scahec.net/view/product/32. Retrieved 2 August 2008. 
  8. ^ Star Publications. "‘Outbreak actions protected by law’". http://thestar.com.my/news/story.asp?file=/2008/7/16/courts/21834412&sec=courts. Retrieved 2 August 2008. 
  9. ^ The State of Queensland Government. "Legislation and Powers of Entry". http://www.health.qld.gov.au/dengue/managing_outbreaks/legislation.asp. Retrieved 2 August 2008. 

External links

Wikimedia Foundation. 2010.


Look at other dictionaries:

  • Outbreak — Título Estallido (España) Epidemia (Hispanoamérica) Ficha técnica Dirección Wolfgang Petersen Producción Gail Katz Arnold Kopelson …   Wikipedia Español

  • outbreak — out break , n. 1. A bursting forth; eruption; insurrection; mutiny; revolt. Mobs and outbreaks. J. H. Newman. [1913 Webster] The flash and outbreak of a fiery mind. Shak. [1913 Webster] 2. A sudden beginning of a violent event; as, the outbreak… …   The Collaborative International Dictionary of English

  • outbreak — (n.) eruption (of disease, hostilities, etc.), c.1600, from OUT (Cf. out) + BREAK (Cf. break) (v.). Outbreak was a verb in Middle English (c.1300) …   Etymology dictionary

  • outbreak — I noun affray, aggression, agitation, assault, attack, bloodshed, blow up, brawl, breach, breach of the peace, burst, cataclysm, commotion, conflict, convulsion, declaration of war, disruption, disturbance, ebullition, eruption, explosion,… …   Law dictionary

  • outbreak — [n] sudden happening beginning, blowup, brawl, break, breaking, burst, bursting, commencement, commotion, convulsion, crack, crash, dawn, detonation, discharge, disorder, disruption, ebullition, effervescence, epidemic, eruption, explosion, fit,… …   New thesaurus

  • outbreak — ► NOUN ▪ a sudden or violent occurrence of war, disease, etc …   English terms dictionary

  • outbreak — [out′brāk΄] n. 1. a breaking out; sudden occurrence, as of disease or war 2. an insurrection or riot …   English World dictionary

  • outbreak — 01. With tensions mounting between the different ethnic groups, the U.N. fears the [outbreak] of a civil war. 02. Decreased tourist revenues are believed to be the result of the SARS [outbreak] in Canada. 03. The Queen s visit has been postponed… …   Grammatical examples in English

  • Outbreak — Filmdaten Deutscher Titel Outbreak – Lautlose Killer Originaltitel Outbreak …   Deutsch Wikipedia

  • outbreak — noun ADJECTIVE ▪ large, major, serious, severe ▪ fresh (esp. BrE), further (esp. BrE), new ▪ recent …   Collocations dictionary

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