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Classical swine fever
The signs 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 (1962), 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. 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 clinical signs. Highly virulent strains correlate with acute, obvious disease and high mortality, including neurological signs and hemorrhages within the skin.
Less virulent strains can give rise to subacute or chronic infections that may escape detection, while still causing abortions and stillbirths. In these cases herds in high-risk areas are usually serologically tested on a thorough statistical basis.
Infected piglets born to infected but subclinical sows help maintain the disease within a population. Other signs can include lethargy, fever, immunosuppression, chronic diarrhoea and secondary respiratory infections. The incubation period of CSF ranges from 2 to 14 days, but clinical signs may not be apparent until after 2 to 3 weeks. Preventive State Regulations usually assume 21 days as the outside limit of the incubation period. 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, diagnosis and slaughter. This may possibly be followed by emergency vaccination (ATCvet codes: QI09 for the inactivated viral vaccine, QI09 for the live vaccine). Vaccination is only used where the virus is widespread in the domestic pig population and/or in wild or feral pigs. In the latter case a slaughter policy alone is usually impracticable. 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.
- Direct immunofluorescence—detection of virus in histological edges
- Indirect immunofluorescence—detection of specific antibodies from sera
- Histology of the brain shows vasculo-endothelial proliferation and peri-vascular cuffing (cuffing is highly suggestive when accompanied by other signs but is not pathonomonic for the disease).