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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 ?
The high epizootic prevalences of 1986 and 1987, reported in this paper, were also recorded in the Chesapeake Bay and were, according to Ford and Bushek (2012), the highest ever recorded in the Delaware Bay.
The 2005-2006 epizootic spread a relatively short distance from the lower density wolf habitats in Worgona Valley to the adjacent high-density habitats in Sanetti, where the disease died out.
Experimental transmission of epizootic bovine abortion (foothill abortion).
As we failed to show a case of bacterial epizootic within termite groups, and because of the apparent absence of mycosis in any of the cadavers, we did not pursue the study further.
Thus, prairie dog colonies could maintain low levels of infected fleas as 'reservoirs' without an epizootic transpiring.
The few years immediately following the 1985-86 MSX epizootic event and preceding the onset of Dermo circa 1990 were not unusual in any way, and neither was the first half-decade after Dermo became an important contributor to population mortality.
Together we must strive to prevent the introduction of epizootic diseases into the UK and whilst we can reduce the likelihood we cannot prevent it.
ABSTRACT The emergence of epizootic shell disease in the American lobster (Homarus americanus) has been devastating to the fishing industry in southern New England.
Avian poxvirus epizootic in a breeding population of lesser flamingos (Phoenicopterus minor) at Kamfers Dam, Kimberley, South Africa.
16, 2011 /PRNewswire-USNewswire/ -- Pennsylvania Game Commission officials today announced that test results from a wild deer have confirmed that epizootic hemorrhagic disease (EHD) has been found in Northampton County.
Grooming and necrophagy in association with gut antifungal activity provides an environment that reduces the chances for the fungus to produce an epizootic into the termite nest.
of Connecticut Health Center) in this text provide encyclopedic coverage of the microbiological, immunological, genetic, and epizootic facets of pathogenic Borrelia, the Lyme disease spirochete.