The clinical sign of African Swine Fever (ASF) and Classical Swine Fever (CSF) are very similar and either disease may occur in acute, sub-acute or chronic forms. In the acute form, pigs develop a high temperature (105 °F), become dull and lose their appetite. Other clinical signs are variable but will include some or all of the following:

  • Vomiting
  • Diarrhea (sometimes bloody)
  • Reddening or darkening of the skin, particularly the ears and snout
  • Gummed-up eyes
  • Laboured breathing and coughing
  • Abortion, still births and weak litters
  • Weakness and unwillingness to stand


African swine fever is a highly contagious viral disease of pigs and very similar in its clinical presentation to classical swine fever. The viruses are distinct and classified in different families. Some strains of ASF virus cause severe disease and high mortality; CSF is usually less dramatic. Classical swine fever and ASF are both transmitted by direct contact between pigs and also through eating infected meat products. Ornithodoros ticks, where present, can act as vectors of the ASF virus; CSF is not transmitted by ticks.

African swine fever was first recorded in Kenya in 1921, and it is present in most sub-Saharan African countries. It spread to southern Europe in 1957 but has persisted only in Sardinia (Italy). There have been no reported outbreaks of ASF in other European countries since a 1999 outbreak in Portugal. In 1978, ASF was introduced to the island of Hispaniola (shared by the Dominican Republic and Haiti) and it was feared it might be introduced to the U.S., particularly the feral swine of Florida. Ticks of the genus Ornithodorus are capable of transmitting ASF, and are present in Florida. African swine fever has never occurred in North America.

Classical swine fever has been eradicated from the U.S., but it still occurs widely around the world and in countries of the Caribbean. Both viruses are transmitted in uncooked pork products prepared from infected pigs. In view of the large numbers of international travelers arriving in the U.S., customs officials in Florida pay particular attention to potentially infected meat products being accidentally or intentionally introduced to the U.S. However, no inspection system is perfect and Florida is considered one of the states where the viruses of ASF and CSF are most likely to be introduced. If either virus were introduced and to cause disease in Florida swine, exports of pork from the entire U.S., not just Florida, would be subject to trade embargoes.