encephalomyocarditis

Encephalomyocarditis virus (EMCV) is a member of the genus Cardiovirus in the family Picornaviridae. It is a nonenveloped, icosahedral, positive-sense RNA virus that infects a broad range of mammals, with particular impact on swine, where outbreaks can cause myocarditis and sudden death, especially in suckling and early-weaned piglets. The name reflects historical observations of encephalitis and myocarditis in affected animals; the virus was first identified in rodents and primates in the mid-20th century.

Host range and transmission are centered on rodents as the primary reservoir. EMCV is shed in feces and urine and can contaminate feed and water. Pigs become infected mainly through oral exposure to contaminated material. Outbreaks are often associated with high mortality in young pigs, though older animals can be affected as well. Species other than swine can experience disease, and accidental infections in humans, while rare, have been documented.

Clinical signs and pathology vary by species. In pigs, affected individuals may die suddenly or develop fever, dyspnea, and signs of congestive heart failure; survivors can show reduced growth and lethargy. Necrotizing myocarditis with inflammatory infiltration is a common lesion. CNS involvement is less typical but can occur in some cases. In humans, EMCV infection is uncommon and usually mild or asymptomatic; when symptomatic, it may present as febrile illness, myocarditis, or meningitis.

Diagnosis relies on laboratory confirmation by virus isolation, RT-PCR, or serology (neutralization or ELISA). There is no specific antiviral treatment; management is supportive. Prevention focuses on rodent control, biosecurity, and preventing contamination of feed and water supplies. Vaccines for EMCV are not widely used in routine practice, and there is no approved human vaccine. EMCV remains an important consideration in pig health and animal husbandry in regions with endemic rodent populations.