Epidemic


Epidemic

In epidemiology, an epidemic (επι (epi)- meaning "upon or above" and δεμος (demos)- meaning "people"), occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience.[1]:354[2] Epidemiologists often consider the term outbreak to be synonymous to epidemic, but the general public typically perceives outbreaks to be more local and less serious than epidemics[2][1]:55, 354

An epidemic may be restricted to one locale, however if it spreads to other countries or continents and affects a substantial number of people, it may be termed a pandemic.[1]:55 The declaration of an epidemic usually requires a good understanding of a baseline rate of incidence; epidemics for certain diseases, such as influenza, are defined as reaching some defined increase in incidence above this baseline.[2] A few cases of a very rare disease may be classified as an epidemic, while many cases of a common disease (such as the common cold) would not.

Contents

Causes of epidemics

There are several changes that may occur in an infectious agent that may trigger an epidemic these include:[1]:55

  • Increased virulence
  • Introduction into a novel setting
  • Changes in host susceptibility to the infectious agent
  • Changes in host exposure to the infectious agent

An epidemic disease is not required to be contagious,[2][3] and the term has been applied to West Nile fever[2] and the obesity epidemic, among others.[3]

Types of epidemics

Common source outbreak

One example of a common source outbreak is the epidemic of Emmititus, the disease reflected in the growth of the skull. In a common source outbreak, the affected individuals had an exposure to a common agent. If the exposure is singular and all of the affected individuals develop the disease over a single exposure and incubation course, it can be termed a point source outbreak. If the exposure was continuous or variable, it can be termed a continuous outbreak or intermittent outbreak, respectively.[1]:56

Propagated outbreak

In a propagated outbreak, the disease spreads person-to-person. Affected individuals may become independent reservoirs leading to further exposures.[1]:56

Many epidemics will have characteristics of both common source and propagated outbreaks. For example, secondary person-to-person spread may occur after a common source exposure or a environmental vectors may spread a zoonotic diseases agent.[1]:56-58

Etymology

The term epidemic derives from a term first attributed to Homer's Odyssey, which later took its medical meaning from a treatise by Hippocrates, Epidemics.[3] Prior to Hippocrates, epidemios, epidemeo, epidamos and other variants had meanings similar to the current definitions of "indigenous" or "endemic".[3] Thucydides's description of the Plague of Athens is considered one of the earliest accounts of a disease epidemic.[3]

See also

Organizations:

Notes

  1. ^ a b c d e f g Principles of Epidemiology, Second Edition. Atlanta, Georgia: Centers for Disease Control and Prevention. http://www2a.cdc.gov/phtn/catalog/pdf-file/Epi_course.pdf. 
  2. ^ a b c d e Green MS, Swartz T, Mayshar E, Lev B, Leventhal A, Slater PE, Shemer J (January 2002). "When is an epidemic an epidemic?". Isr. Med. Assoc. J. 4 (1): 3–6. PMID 11802306. http://www.ima.org.il/imaj/ar02jan-1.pdf. 
  3. ^ a b c d e Martin PM, Martin-Granel E (June 2006). "2,500-year evolution of the term epidemic". Emerging Infect. Dis. 12 (6): 976–80. PMID 16707055. http://wwwnc.cdc.gov/eid/content/12/6/pdfs/v12-n6.pdf. 

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  • Epidemic — Ep i*dem ic, Epidemical Ep i*dem ic*al, a. [L. epidemus, Gr. ?, ?, among the people, epidemic; ? in + ? people: cf. F. [ e]pid[ e]mique. Cf. {Demagogue}.] 1. (Med.) Common to, or affecting at the same time, a large number in a community; applied… …   The Collaborative International Dictionary of English

  • Epidemic — est un film danois réalisé par Lars von Trier, sorti en 1987. C est le deuxième volet de sa trilogie Europe (les 2 autres volets étant: Element of Crime et Europa). Sommaire 1 Synopsis 2 Fiche technique 3 Distribution …   Wikipédia en Français

  • Epidemic — Ep i*dem ic, n. [Cf. {Epidemy}.] 1. (Med.) An epidemic disease. [1913 Webster] 2. Anything which takes possession of the minds of people as an epidemic does of their bodies; as, an epidemic of terror. [1913 Webster] …   The Collaborative International Dictionary of English

  • epidemic — EPIDÉMIC, Ă, epidemici, ce adj. (Despre unele boli) Cu caracter de epidemie; contagios, molipsitor. – Din fr. épidémique. Trimis de viomih, 10.05.2004. Sursa: DEX 98  epidémic adj. m., pl. epidémici; f. sg. epidémică …   Dicționar Român

  • epidemic — (adj.) c.1600, from Fr. épidémique, from épidemié an epidemic disease, from M.L. epidemia, from Gk. epidemia prevalence of an epidemic disease (especially the plague), from epi among, upon (see EPI (Cf. epi )) + demos people, district (see… …   Etymology dictionary

  • epidemic — [adj] widespread catching, communicable, contagious, endemic, general, infectious, pandemic, prevailing, prevalent, rampant, rife, sweeping, wide ranging; concepts 314,537 Ant. limited epidemic [n] widespread disease contagion, endemic, growth,… …   New thesaurus

  • epidemic — ► NOUN 1) a widespread occurrence of an infectious disease in a community at a particular time. 2) a sudden, widespread occurrence of something undesirable. ► ADJECTIVE ▪ relating to or of the nature of an epidemic. ORIGIN Greek epid mia, from… …   English terms dictionary

  • epidemic — [ep΄ə dem′ik] adj. [Fr épidémique < MFr < ML epidemicus < epidemia < Gr epidēmia < epidēmios, among the people, general < epi , EPI + dēmos, people: see DEMOCRACY] prevalent and spreading rapidly among many individuals in a… …   English World dictionary

  • epidemic — index contagious, disease, far reaching, general, pestilent, predominant, prevailing (current), preva …   Law dictionary

  • Epidemic —    Drame de Lars von Trier, avec Lars von Trier, Niels Vörsel, Udo Kier.   Pays: Danemark   Date de sortie: 1987   Technique: noir et blanc   Durée: 1 h 46    Résumé    En écrivant un scénario relatant les aventures d un médecin lors de la grande …   Dictionnaire mondial des Films


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