Classical swine fever

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Classical swine fever virus

Virus classification

Group:	Group IV ((+)ssRNA)
Family:	Flaviviridae
Genus:	Pestivirus
Species:	Classical swine fever virus

Classical swine fever (CSF) or hog cholera (also sometimes called pig plague based on the German word Schweinepest) is a highly contagious disease of pigs and wild boar. It causes fever, skin lesions, convulsions and usually (particularly in young animals) death within 15 days. The symptoms are indistinguishable from those of African swine fever. The disease is endemic in much of Asia, Central and South America, and parts of Europe and Africa. It was believed to have been eradicated in the United Kingdom by 1966 (according to the Department for Environment, Food & Rural Affairs), but an outbreak occurred in East Anglia in 2000. It was eradicated in the USA by 1978, according to the United States Department of Agriculture. Other regions believed to be free of CSF include Australia, Canada, Ireland, New Zealand and Scandinavia.

The infectious agent responsible is a virus CSFV (previously called hog cholera virus) of the genus Pestivirus in the family Flaviviridae (or Togaviridae [1]). CSFV is closely related to the ruminant pestiviruses which cause Bovine Viral Diarrhoea (BVDV) and Border Disease (BDV).

The effect of different CSFV strains varies widely, leading to a wide range of symptoms. Highly virulent strains correlate with acute, obvious disease and high mortality, including neurological symptoms and haemorrhages within the skin. Less virulent strains can give rise to subacute or chronic infections that may escape detection, while still inducing mortality in fetuses and new-borns. Infected piglets birthed from infected but subclinical sows help maintain the disease within a population. Other symptoms can include lethargy, fever, immunosuppression and secondary respiratory infections. The incubation period of CSFV ranges from 2 to 14 days but symptoms may not be apparent until after 2 to 4 weeks. Animals with an acute infection can survive 2 to 3 months before their eventual death.

Eradicating CSF is problematic. Current programmes revolve around rapid detection and diagnosis, and preventive culling, possibly followed by emergency vaccination. Possible sources for maintaining and introducing infection include the wide transport of pigs and pork products, as well as endemic CSF within wild boar and feral pig populations.