, an epizootic
(from Greek epi-
upon + zoion
animal) is a disease
that appears as new cases in a given animal population, during a given period, at a rate that substantially exceeds what is "expected" based on recent experience (i.e.
a sharp elevation in the incidence
is the analogous term applied to human populations. High population density
is a major contributing factor to epizootics. Aquaculture
is an industry
sometimes plagued by disease because of the large number of fish
confined to a small area.
Defining an epizootic can be subjective, depending in part on what is "expected". An epizootic may be: a) restricted to a specific locale (an outbreak), b) general (an "epizootic") or c) widespread (panzootic). Because it is based on what is "expected" or thought normal, a few cases of a very rare disease (like a TSE outbreak in a Cervid population) might be classified as an "epizootic," while many cases of a common disease (like lymphocystis in Esocids) would not.
Common diseases that occur at a constant but relatively high rate in the population are said to be "enzootic." An example of an enzootic disease would be the influenza virus in some bird populations or, at a lower incidence, the Type IVb strain of VHS in certain Atlantic fish populations.
An example of an epizootic would be the 1990 outbreak of Newcastle disease virus in double-crested cormorant colonies on the Great Lakes that resulted in the death of some 10,000 birds.
Zambia EUS outbreak
On September 14
, 2007, epizootic ulcerative
syndrome (EUS), a mysterious disease killed hundreds of sore
-covered fish in River Zambezi
. The Agriculture Minister of Zambia
, Ben Kapita, asked experts to investigate the outbreak to probe the cause to find out if the disease can be transmitted to humans.