In
epidemiology, an 'epidemic' (from
Greek ''epi-'' upon + ''demos'' people) is a
classification of a disease that appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is "expected," based on recent experience (the number of new cases in the population during a specified period of time is called the "incidence rate"). (An
epizootic is the same thing but for an animal population.)
Defining an epidemic can be subjective, depending in part on what is "expected". An epidemic may be restricted to one locale (an outbreak), more general (an "epidemic") or even global (
pandemic). Because it is based on what is "expected" or thought normal, a few cases of a very rare disease like rabies may be classified as an "epidemic," while many cases of a common disease (like the common cold) would not.
Common diseases that occur at a constant but relatively high rate in the population are said to be "
endemic." An example of an endemic disease is
malaria in some parts of
Africa (for example,
Liberia) in which a large portion of the population is expected to get malaria at some point in their lifetimes.
Famous examples of epidemics include the
bubonic plague epidemic of
Medieval Europe known as ''the
Black Death'', and the
Great Influenza Pandemic concurring with the end of
World War I.
In August 2007, the
World Health Organization reported an unprecedented rate of propagation of
infectious diseases.
[1]
Non-biological usage
The term is often used in a non-biological sense to refer to widespread and growing
societal problems, for example, in discussions of
obesity,
mental illness or
drug addiction.
See also
★
Centers for Disease Control and Prevention (CDC)
★
European Centre for Disease Prevention and Control (ECDC)
★
Endemic
★
Epidemiology
★
Pandemic
★
Syndemic
★
Mathematical modelling in epidemiology
★
List of epidemics
★
Sitala
External links
★
Video Panel Discussion on Pandemics with Experts