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In pigs, disease due to EMC virus may take one of two main forms: an acute myocarditis (usually in piglets) or reproductive failure in sows. Clinical signs may include lethargy, inappetence, trembling, staggering, paralysis, vomiting and dyspnea. Infected piglets frequently die without showing any signs. Reproductive problems include poor conception rates, embryo resorption, mummification, stillbirths, abortions and neonatal death.

Distribution: presumed ubiquitous in wild rodents.

EMC in pigs was first observed in Europe in 1986. Outbreaks of acute myocarditis have been reported in Italy, Greece, Belgium and Cyprus. Reproductive disorders have also been reported in Belgium. Fatal myocarditis occurs in pigs and zoo animals in many parts of the world including the USA (mainly Florida and Louisiana) and Australia (mainly NSW). Recently about 66 free-living elephants were killed in an outbreak in the Kruger National Park, South Africa.

EMC is caused by an RNA virus that is one of three virus species in the genus Cardiovirus in the family Picornaviridae.

Fatal myocarditis due to EMC virus infection has been seen in primates, even-toed ungulates, odd-toed ungulates, elephants, carnivores and rodents. In addition the virus has also been isolated from lagomorphs, marsupials, birds, mosquitoes and ticks. Although EMC virus infection may be fatal in chimpanzees and other higher primates, no deaths have been recorded in man. However, serological surveys suggest that man may be infected and EMC viruses were isolated from children suffering from CNS disease during the 1950s.

Spread is thought to be by consumption of infected rodent carcases or foodstuffs contaminated with rodent urine/faeces. Transmission has been demonstrated experimentally between pigs kept in close contact. Cannibalism may sometimes play a role.

Nick Knowles