ASF is currently confined to the African continent, the Republic
of Cape Verde, Madagascar and Sardinia. An outbreak was also
reported in Portugal in 1999.
It has been reported from or is known to occur in all southern,
central and eastern African countries south of a line drawn
along the northern borders of Congo (Brazzaville), Democratic
Republic of Congo, Uganda and Kenya, with the exception of
Swaziland and Lesotho. It is endemic in domestic pigs in several
countries, including Angola, Democratic Republic of Congo,
Uganda, Zambia, Malawi and Mozambique.
In West Africa, ASF appears to be endemic in two islands of the Cape Verde Archipelago, Senegal, Gambia, Cameroon and probably Guinea Bissau. Since 1996, epidemics have been experienced in Côte d'Ivoire, Benin, Togo, Nigeria and Ghana.
The source of the recent epidemics has not been traced, but molecular studies have shown that the virus isolated from the majority of outbreaks belongs to the West African lineage, which included viruses isolated from outbreaks in Europe, Brazil and Angola.
The introduction of this highly fatal disease into areas where there are large concentrations of pigs is unlikely to pass unnoticed, and the first cases of ASF have almost always been reported in and around large cities. Detection of the disease is problematic in remote areas where herds are small and veterinary personnel are scarce and in countries where serious civil unrest prevents normal activities.