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Also known as: ''''' EMC '''''—''''' Encephalomyocarditis Virus disease of Pigs '''''—''''' EMCV '''''

Also known as: ''''' EMC '''''—''''' Encephalomyocarditis Virus disease of Pigs '''''—''''' EMCV '''''

{{Taxobox

{{Taxobox

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==Introduction==

==Introduction==

'''Encephalomyocarditis virus (EMCV)''' is a single stranded RNA (ssRNA) virus that causes encephalomyocarditis in pigs. It is a '''cardiovirus''' from the family [[Picornaviridae| Picornaviridae]], and like other picornaviruses it stable over a wide range of pH. The virus is ether-resistant and can be inactivated at 60°C for 30 minutes, although some are more thermally stabile.

'''Encephalomyocarditis virus (EMCV)''' is a single stranded RNA (ssRNA) virus that causes encephalomyocarditis in pigs. It is a '''cardiovirus''' from the family [[Picornaviridae| Picornaviridae]], and like other picornaviruses it stable over a wide range of pH. The virus is ether-resistant and can be inactivated at 60°C for 30 minutes, although some are more thermally stable.

EMCV causes high mortality in young pigs and reproductive failures in breeding females. Piglets suffer from myocarditis and encephalitis and sudden death due to myocardial failure is common.  The disease affects the nervous, reproductive, respiratory and circulatory system of pigs. Antibodies for EMCV have been demonstrated in human populations <ref name="Tesh, 1978">Tesh, R.B. (1978).'''The prevalence of encephalomyocarditis virus neutralizing antibodies among various human populations'''. ''American Journal of Tropical Medicine & Hygiene'', 27:144-149.</ref> but there are no reports that the virus causes human heart disease.

EMCV causes high mortality in young pigs and reproductive failures in breeding females. Piglets suffer from myocarditis and encephalitis and sudden death due to myocardial failure is common.  The disease affects the nervous, reproductive, respiratory and circulatory system of pigs. Antibodies for EMCV have been demonstrated in human populations <ref name="Tesh, 1978">Tesh, R.B. (1978).'''The prevalence of encephalomyocarditis virus neutralizing antibodies among various human populations'''. ''American Journal of Tropical Medicine & Hygiene'', 27:144-149.</ref> but there are no reports that the virus causes human heart disease.

==Epidemiology==

==Epidemiology==

The mode of virus transmission is not clear but rodent-to-pig transmission is probably common and rodents act as the '''major reservoir of the disease. Rats and other rodents probably infect pigs directly or through diseased carcasses and contaminated feeds or water supplies.

The mode of virus transmission is not clear but rodent-to-pig transmission is probably the most important and common, and rodents act as the '''major reservoir of the disease. Rats and other rodents probably infect pigs directly or through diseased carcasses and contaminated feeds or water supplies.

 

Infected pigs can shed the virus in faeces but pig to pig transmission has not yet been proved experimentally, even though it is likely that it occurs.

The route of infection in swine is likely to be oral and experiments have shown this to be the case. Virus can be shed from infected pigs for up to 9 days in their faeces. Animals that survive acute disease produced EMCV antibodies and the course of infection depends upon the virus strain, dose, history and the individual’s immune system. Further experiments have shown that intramuscular infection can cause transplacental infection and foetal deaths in pregnant sows. <ref name="Love and Grewal, 1986"> Love, R.J., Grewal, A.S., (1986). '''Reproductive failure in pigs caused by encephalomyocarditis virus'''. ''Australian Veterinary Journal'', 63(4):128-129; 3 ref.</ref>

The route of infection in swine is likely to be oral and experiments have shown this to be the case. Virus can be shed from infected pigs for up to 9 days in their faeces. Animals that survive acute disease produced EMCV antibodies and the course of infection depends upon the virus strain, dose, history and the individual’s immune system. Further experiments have shown that intramuscular infection can cause transplacental infection and foetal deaths in pregnant sows. <ref name="Love and Grewal, 1986"> Love, R.J., Grewal, A.S., (1986). '''Reproductive failure in pigs caused by encephalomyocarditis virus'''. ''Australian Veterinary Journal'', 63(4):128-129; 3 ref.</ref>

Infected foetuses can grossly vary depending on the stage of pregnancy and infection and myocardial lesions may be indistinguishable from other viral infections. Foetuses can be haemorrhagic, oedematous or apparently normal.  

Infected foetuses can grossly vary depending on the stage of pregnancy and infection and myocardial lesions may be indistinguishable from other viral infections. Foetuses can be haemorrhagic, oedematous or apparently normal.  

'''Histopathological''' findings include myocarditis with focal or diffuse accumulation of mononuclear cells, vascular congestion, oedema, degeneration of the myocardial fibres with necrosis and occasional mineralization of necrotic heart muscle. Brain tissue can be congestion with evidence of meningitis, perivascular infiltration (mononuclear cells) and neuronal degeneration.  Nonsuppurative encephalitis and myocarditis has also been seen in naturally infected swine foetuses.   

'''Histopathological''' findings include myocarditis with focal or diffuse accumulation of mononuclear cells, vascular congestion, oedema, degeneration of the myocardial fibres with necrosis and occasional mineralization of necrotic heart muscle. Brain tissue can be congested with evidence of meningitis, perivascular infiltration (mononuclear cells) and neuronal degeneration.  Nonsuppurative encephalitis and myocarditis has also been seen in naturally infected swine foetuses.   

Detection of antibody specific to EMCV from still-born piglets has been used to confirm foetal infection <ref name="Joo et al., 1988"> Joo, H.S., Kim, H.S., Leman, A.D., (1988) '''Detection of antibody to encephalomyocarditis virus in mummified or stillborn pigs'''. ''Archives of Virology'', 100(1-2):131-134; 9 ref.</ref>  <ref name="Kim et al., 1991"> Kim, H.S., Joo, H.S., Christianson, W.T., Morrison, R.B., (1991) '''Evaluation of serologic methods for detection of antibodies to encephalomyocarditis virus in swine fetal thoracic fluids'''. ''Journal of Veterinary Diagnostic Investigation'', 3(4):283-286; 20 ref.</ref>

Detection of antibody specific to EMCV from still-born piglets has been used to confirm foetal infection <ref name="Joo et al., 1988"> Joo, H.S., Kim, H.S., Leman, A.D., (1988) '''Detection of antibody to encephalomyocarditis virus in mummified or stillborn pigs'''. ''Archives of Virology'', 100(1-2):131-134; 9 ref.</ref>  <ref name="Kim et al., 1991"> Kim, H.S., Joo, H.S., Christianson, W.T., Morrison, R.B., (1991) '''Evaluation of serologic methods for detection of antibodies to encephalomyocarditis virus in swine fetal thoracic fluids'''. ''Journal of Veterinary Diagnostic Investigation'', 3(4):283-286; 20 ref.</ref>

==Treatment==

==Treatment==

It is important to '''control rodent populations''' on farm to prevent the spread of disease and contamination of feeds or water supply. Good husbandry and hygiene protocols should be followed with the regular use of disinfectants.  

It is important to '''control rodent populations''' on farm to prevent the spread of disease and contamination of feeds or water supply. Good husbandry and hygiene protocols should be followed with the regular use of disinfectants.  

==References==

==References==

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{{Learning

{{Mandy Nevel

|flashcards = [[Encephalomyocarditis Virus Flashcards]]

|date = 09 September 2011}}

}}

[[Category:Picornaviridae]]

[[Category:Picornaviridae]]

[[Category:Pig Viruses]]

[[Category:Pig Viruses]]

[[Category:Neurological Diseases - Pig]]

[[Category:Neurological Diseases - Pig]]

[[Category:To Do - Jaimie Meagor]]

[[Category:CABI Expert Review Completed]][[Category:CABI AHPC Pages]]

[[Category:Cardiology Section]]