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(veterinary medicine)
Affecting many animals of one kind in one region simultaneously; widely diffuse and rapidly spreading.
An extensive outbreak of an epizootic disease.



a widely spreading contagious disease (infectious or infestatant) of animals, with morbidity far in excess of that ordinarily (sporadically) observed in a particular locality. The study of epizootics is called epizootiology.

An epizootic is characterized by the steady spread of an infectious disease and a microbe-carrier state among animals. An epizootic can occur only in the presence of a number of interdependent elements that constitute an epizootic chain: the source of the causative agent (a diseased animal or animal microbe-carrier), live transmitters or environmental factors conducive to infection, and susceptible animals. The outbreak and spread of an epizootic are influenced by geographic, climatic, soil, and other environmental conditions and economic factors, including agricultural conditions, as well as social upheavals, such as war or economic crisis. The nature and duration of an epizootic vary depending on the means of transmission of the causative agent, the length of the incubation period, the ratio of diseased to susceptible animals, the conditions under which animals are maintained, and the effectiveness of the countermeasures.

Epizootics of certain diseases may occur periodically, usually every few years. They tend to break out seasonally and to have specific stages of development. All of these characteristics are most evident when the epizootic progresses spontaneously. Intervention by man, specifically the use of countermeasures, as in the USSR, to a considerable degree prevents the spread of epizootics.

References in periodicals archive ?
bolitinos to oral infection with eight serotypes of epizootic haemorrhagic disease virus.
Health-care providers in areas with documented epizootic activity should consider WNV infection in persons with suspected viral meningitis (especially among adults) or encephalitis (regardless of age).
A blood sample from an infected seal from the 1988 epizootic was obtained from Albert Osterhaus, Erasmus University (Rotterdam, the Netherlands).
Epizootiology of an epizootic hemorrhagic disease outbreak in West Virginia.
According to British veterinary experts, the risk of the epizootic disease spreading to regions other than Surrey is "very low" from this point on.
This epizootic has been associated with raccoon rabies in domestic and wild animals, including one black bear and 31 white-tailed deer.
8 million, measures will be taken to curb and eradicate the new outbreaks of avian influenza, to increase epizootic readiness on the territory of the country and to compensate the owners of killed animals.
They believe that using the AM allergen in the set of diagnostic studies when differentiating tuberculin reactions in animals at arbitrarily satisfactory farmsteads allows understanding, to a certain extent, the epizootic situation in terms of TB among cattle (Michel, 2008).
In 2014, Bluetongue disease was the most serious epizootic problem in Bulgaria, spreading in 2,322 settlements in all regions of the country, and about 37,000 sheep and 300 cattle died, Likov said.
During 2002-2013, Web Valley wolf packs were affected by rabies epizootics in 2003 and 2008-2009 and by an CDV epizootic in 2010 (Figure 4).
Though one case of squirrel pox is by no means indicative of a large-scale epizootic risk, it is worth noting that in other species, in different geographic locations, this pathogen has reached epizootic proportions.