epizoology Epizootiology, epizoology, or veterinary epidemiology is the study of disease patterns within animal populations. See also * Epizootic * Epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns ...

, an epizootic (or epizoötic, from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

: ''epi-'' "upon" + ''zoon'' "animal") is a

disease A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...

event in a nonhuman

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

population analogous to an

epidemic An epidemic (from Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of hosts in a given population within a short period of time. For example, in meningococcal infection ...

in humans. An epizootic disease (or ) may occur in a specific locale (an "

outbreak In epidemiology, an outbreak is a sudden increase in occurrences of a disease when cases are in excess of normal expectancy for the location or season. It may affect a small and localized group or impact upon thousands of people across an entire ...

"), more generally (an "epizootic"), or become widespread (" panzootic"). High population density is a major contributing factor to epizootics. The

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

industry is sometimes plagued by disease because of the large number of

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

confined 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 the incidence rate). Because the judgement is based on what is "expected" or thought normal, a few cases of a very rare disease (like a transmissible spongiform encephalopathy 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 class as " enzootic" (compare the epidemiological meaning of "endemic" for human diseases). An example of an enzootic disease would be the

influenza Influenza, commonly known as the flu, is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These sympto ...

virus in some bird populations or, at a lower incidence, the Type IVb strain of viral hemorrhagic septicemia in certain Atlantic fish populations. An example of an epizootic was the 1990 outbreak of

Newcastle disease Virulent Newcastle disease (VND), formerly exotic Newcastle disease, is a contagious viral avian disease affecting many domestic and wild bird species; it is transmissible to humans. Though it can infect humans, most cases are non-symptomati ...

virus in double-crested cormorant colonies on the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...

that resulted in the death of some 10,000 birds.Viral Hemorrhagic Septicemia (VHS) - HSL
''www.usgs.gov'', accessed 8 May 2020

References

{{Authority control Animal diseases History of veterinary medicine