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 A panzootic (from Greek παν all + ζόιον animal) is an epizootic (an outbreak of an infectious disease of non-human animals) that spreads across a large region (for example a continent), or even worldwide. The equivalent in human populati ...

"). 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 Industry may refer to: Economics * Industry (economics), a generally categorized branch of economic activity * Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery * The wider industrial sector ...

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 Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of progressive, incurable, and fatal conditions that are associated with the prion hypothesis and affect the brain and nervous system of many animals, in ...

outbreak in a

cervid A deer (: deer) or true deer is a hoofed ruminant ungulate of the family Cervidae (informally the deer family). Cervidae is divided into subfamilies Cervinae (which includes, among others, muntjac, elk (wapiti), red deer, and fallow deer) a ...

population) might be classified as an "epizootic", while many cases of a common disease (like

lymphocystis Lymphocystis is a common viral disease of freshwater and saltwater fish. The virus that causes this disease belongs to the genus '' Lymphocystivirus'' of the family Iridoviridae. Aquarists often come across this virus when their fish are stress ...

in esocids) would not. Common diseases that occur at a constant but relatively high rate in the population class as "

enzootic Enzootic describes the situation where a disease or pathogen is continuously present in at least one species of non-human animal in a particular region. It is the non-human equivalent of endemic. In epizoology, an infection is said to be "''enzo ...

" (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 Viral hemorrhagic septicemia (VHS) is a deadly infectious fish disease caused by Viral hemorrhagic septicemia virus. It afflicts over 50 species of freshwater and marine fish in several parts of the Northern Hemisphere. Different strains of the v ...

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 The double-crested cormorant (''Nannopterum auritum'') is a member of the cormorant family of water birds. It is found near rivers and lakes and in coastal areas and is widely distributed across North America, from the Aleutian Islands in Alaska ...

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