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African Swine Fever (ASF)

The Disease

African Swine Fever (ASF) is a highly contagious, generalized disease of pigs caused by an Iridovirus of family Asfarviridae that exhibits varying virulence between strains and is very hardy to physical and chemical inactivation. The agent can remain viable for long periods in blood, faeces and tissues. It can also multiply in its vectors. In view of this, the control of ASF is dependent on stamping out policy and strict quarantine enforcement. It most commonly appears in the acute form as a haemorrhagic fever. Subacute and chronic forms of the disease also exist. Mortality is usually close to 100 percent and pigs of all ages are affected.

Geographical Distribution

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.

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