Classical swine fever is a highly contagious virus disease of swine. No other animals are affected. First recognised in Tennessee in 1810, it then rapidly spread around the world. It was first seen in Great Britain in 1864 and controls were instigated in 1878. The disease was eradicated from the country in 1966. Since then breakdowns have occurred in 1971 (215 pigs slaughtered), 1986 (7,800 pigs slaughtered) and most recently in 2000 in East Anglia when 75,000 diseased and in-contact pigs were slaughtered before the disease was beaten.

In the acute form of the disease, affected pigs develop a very high temperature followed by a variety of other clinical signs which may include coughing, diarrhoea, abortion, skin lesions and nervous signs. In young pigs the mortality rate may approach 100%. Apparently healthy pigs may be incubating the disease and recovered pigs can carry on excreting the virus and so be a source of infection for others. This means that movements of pigs from farms can easily spread the disease. The virus can also remain in the environment, for example on people, boots and lorries and this is another source of spread and infection.

The disease is controlled by various means. There are very strict controls on the import of meat and meat products into the UK - the outbreak in 2000 was suspected to have been caused by pigs (or a pig) consuming a contaminated imported pig product. Movement orders, in place since 1995, prevent the movement of pigs from a farm until 20 days after pigs have moved on. By law, all owners must inform DEFRA immediately if any sick pigs are showing any signs suggestive of swine fever. All affected and in-contact animals are slaughtered. In addition no feeding of swill to pigs is allowed.

Other EU countries have had large numbers of outbreaks, with Holland in 1997 taking over a year to bring an outbreak under control. Currently the all - slaughter policy is still in use, but cost-benefit analysis into the use of vaccines have shown that their use may decrease the cost of an outbreak. However at present there is not a vaccine available where vaccinated pigs on test can be differentiated from infected ones.

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