Exotic Diseases

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Species Infected

affects only pigs

• newly described syndrome in both Europe and North America

Clinical Signs

• incubation period 3-5 days
• first signs anorexia, fever, cyanosis
• consequent signs depend on age and breeding status of animals
• young piglets
• preweaning mortality 10-40%
• survivors may have abdominal breathing, diarrhoea
• grower and finisher pigs
• influenza-like illness
• may be ill up to 3 weeks
• mortality 1-5%
• breeding sows
• sudden deaths 1-2%
• late abortions 1-2%
• premature farrowing 1-20%
• farrowings with dead, live and dead and/or mummified foetuses
• increased farrowing interval
• retained placentae

Lesions

• mortalities associated with pneumonia often complicated by secondary bacterial infection

Aetiology

• Arterivirus (Togaviridae) only provisionally classified

Pathogenesis

• viraemia follows respiratory tract infection
• infects a variety of white blood and lymphoid cells, and macrophages
• virus then crosses placenta

Epidemiology

• direct pig to pig transmission
• aerosol spread important and reported to occur up to 20 kms
• fomites not implicated
• some immunity occurs but not complete and some animals can be clinically ill again
• some animals can become chronic carriers

Differential Diagnosis

     1.  proliferative and necrotising pneumonia
     2.  swine influenza
     3.  swine fever (mild strains)
     4.  pseudorabies
     5. other diseases causing reproductive losses and/or respiratory disease