In epidemiology, an epidemic (from επί (epi), meaning "upon or above" and δήμος (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. 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.

Epidemics of infectious disease are generally caused by a change in the ecology of the host population (e.g. increased stress or increase in the density of a vector species), a genetic change in the parasite population or the introduction of a new parasite to a host population (by movement of parasites or hosts). Generally, an epidemic occurs when host immunity to a parasite population is suddenly reduced below that found in the endemic equilibrium and the transmission threshold is exceeded.

An epidemic may be restricted to one location; however, if it spreads to other countries or continents and affects a substantial number of people, it may be termed a pandemic. 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. 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.

Read more about Epidemic:  Causes, Transmission, Etymology

Other articles related to "epidemic, epidemics":

Spanish Conquistadors - Disease in The Americas
... Epidemic disease is commonly cited as the primary reason for the population collapse ... portion of the population, had already died in a smallpox epidemic ... The first epidemic was recorded in 1529 and killed the emperor Huayna Capac, the father of Atahualpa ...
Squamish History - Assimilation and Discrimination - Epidemic
... Around 1782, a smallpox epidemic hit the Sḵwx̱wú7mesh, coming in through networks in the trade with other nations, then spreading throughout the villages ...
Groningen Epidemic
... (also called ‘intermittent fevers’) that broke out in 1826 was a malaria epidemic that killed 2,844 people—nearly 10% of the population of the city of Groningen ... of Groningen in 1826 in the subsequent hot spring and summer of 1826 led to the epidemic ... The epidemic also hit Friesland and the German Wadden Sea region ...
Epidemic - 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 ... Plague of Athens is considered one of the earliest accounts of a disease epidemic ...
San Pascualito - History
... The man was dying from an epidemic fever called cucumatz in Kaqchikel, and had received the last rites before a tall skeleton in glowing robes appeared to him in a ... the man receiving the vision would die within nine days, at which time the epidemic would also cease ... When the man died within the predicted timeframe and the epidemic ended, word of the vision spread, and images of San Pascualito became popular despite formal prohibition by the Spanish Inquisition ...

Famous quotes containing the word epidemic:

    This movie deals with the epidemic of the way we live now.
    What an inane cardplayer. And the age may support it.
    John Ashbery (b. 1927)