Epizootic

Not to be confused withEpizoic.

Inepizoology,anepizootic(orepizoötic,fromGreek:epi-"upon" +zoon"animal" ) is adiseaseevent in a nonhumananimalpopulation analogous to anepidemicin humans. An epizootic disease (orepizooty) may occur in a specific locale (an "outbreak"), more generally (an" epizootic "), or become widespread ("panzootic"). Highpopulation densityis a major contributing factor to epizootics. Theaquacultureindustryis sometimes plagued by disease because of the large number offishconfined to a small area.

Defining and declaring an epizootic can be subjective; health authorities evaluate the number of new cases in a given animal population during a given period, and estimate a rate of spread that substantially exceeds what they might expect based on recent experience (i.e.a sharp elevation in theincidencerate). Because the judgement is based on what is "expected" or thought normal, a few cases of a very rare disease (like atransmissible spongiform encephalopathyoutbreak in acervidpopulation) might be classified as an "epizootic", while many cases of a common disease (likelymphocystisinesocids) would not.

Common diseases that occur at a constant but relatively high rate in the population class as "enzootic"(compare the epidemiological meaning of"endemic"for human diseases). An example of an enzootic disease would be theinfluenzavirus in some bird populationsor, at a lower incidence, the Type IVb strain ofviral hemorrhagic septicemiain certain Atlantic fish populations.

An example of an epizootic was the 1990 outbreak ofNewcastle diseasevirus indouble-crested cormorantcolonies on theGreat Lakesthat resulted in the death of some 10,000 birds.

See also

• Epidemic
• Enzootic
• Epizoology
• Panzootic
• Equine influenzafor the Great Epizootic of 1872 in the US and Canada
• 1890s African rinderpest epizootic
• Mathematical modelling in epidemiology
• Sylvatic plague
• Wildlife disease