World Organisation for Animal Health

Font size:

Language :


Advanced search

Home > Animal health in the World > Information on aquatic and terrestrial animal diseases


  • Classical Swine Fever was first detected in the United States in the Nineteenth Century.
  • An outbreak in the Netherlands in 1997 led to the destruction of 11 million pigs and cost US$ 2.3 billion.
  • OIE standards for surveillance as applied have helped eradicate CSF from North America and much of Western Europe.


What is Classical swine fever?

Classical swine fever (CSF), also known as hog cholera, is a contagious viral disease of domestic and wild swine. It is caused by a virus of the genus Pestivirus of the family Flaviviridae, which is closely related to the viruses that cause bovine viral diarrhoea in cattle and border disease in sheep. There is only one serotype of CSF virus (CSFV). CSF is a disease listed by the OIE World Organisation for Animal Health (OIE) Terrestrial Animal Health Code and must be reported to the OIE (OIE Terrestrial Animal Health Code).


Transmission and spread

The most common method of transmission is through direct contact between healthy swine and those infected with CSF virus. The virus is shed in saliva, nasal secretions, urine, and feces. Contact with contaminated vehicles, pens, feed, or clothing may spread the disease. Animals that are chronic carriers of the disease (persistently infected) may show no clinical signs of illness but may shed the virus in their feces. Offspring of infected sows can become infected in the uterus, and can shed the virus for months.

CSF virus can survive in pork and processed pork products for months when meat is refrigerated and for years when it is frozen. Pigs can become infected by eating CSF-infected pork meat or products.

It has been proven that in parts of Europe, the wild boar population may play a role in the epidemiology of the disease.

The disease has been spread through legal and illegal transport of animals, and by feeding swill containing infective tissues to pigs.


Public health risk

Humans are not affected by this virus. Swine are the only species known to be susceptible.


Clinical signs

The disease has acute and chronic forms, and can range from severe, with high mortality, to mild or even unapparent.

In the acute form of the disease, in all age groups, there is fever, huddling of sick animals, loss of appetite, dullness, weakness, conjunctivitis, constipation followed by diarrhoea, and an unsteady gait. Several days after the onset of clinical signs, the ears, abdomen and inner thighs may show a purple discoloration. Animals with acute disease die within 1-2 weeks. Severe cases of the disease appear very similar to African swine fever.

With low virulence strains, the only expression may be poor reproductive performance and the birth of piglets with neurologic defects such as congenital tremor.



Because the clinical signs are not exclusive to CSF, and vary widely, laboratory tests are required to detect antibodies or the virus itself. The OIE Manual of Diagnostic Tests and Vaccines describes the testing.


Prevention and control

Treatment is not attempted. Affected pigs must be slaughtered and the carcases buried or incinerated.

The first barrier to prevent an outbreak of the CSF is to apply strict and rigorous sanitary prophylaxis, as defined in the OIE Terrestrial Animal Health Code. A good communication between veterinary authorities, veterinary practitioners and pig farmers, reliable disease reporting system, and hygiene measures protecting domestic pigs from contact with wild boar are the most effective measures to prevent the disease.

When an outbreak occurs, many actions must be set in place urgently:  

  • Slaughter of all pigs on affected farms
  • Safe disposal of carcasses, bedding, etc.
  • Thorough disinfection
  • Designation of infected zone, with control of pig movements
  • Detailed epidemiological investigation, with tracing of possible sources (up-stream) and
  • Surveillance of infected zone, and surrounding area

In areas where the disease is endemic, vaccination can prevent the spread of the disease. Vaccines used should be produced in accordance with the OIE standards for vaccine production. As the disease is brought under control, vaccination ceases, with continued surveillance. The OIE Terrestrial Animal Health Code defines the requirements for a country or a zone to be considered free of the disease.

In disease-free areas, a stamping out policy is applied consisting of early detection, movement control, proper disposal of carcasses, and cleaning and disinfection. This policy has led to the elimination of CSF from North America, and much of Western Europe.


Geographical distribution

CSF is found in Central and South America, Europe, and Asia and parts of Africa. North America, Australia and New Zealand are currently free of the disease. In the 1990’s large CSF outbreaks occurred in The Netherlands (1997), Germany (1993-2000), Belgium (1990, 1993, 1994) and Italy (1995, 1996, 1997).