The virus that causes this disease is physically and behaviourally unique in many respects but only the introduction of domestic pigs to Africa by European missionaries and settlers starting several centuries ago revealed its pathogenic potential. Prior to that, the virus had existed in an underground commensal relationship with warthogs and argasid ticks that live in their burrows and feed on their blood. ASF was first reported as a disease distinct from classical swine fever in Kenya in 1921, followed shortly by Angola and South Africa. However, in the last 50-60 years the virus has shown a remarkable ability to infect pigs and has invaded many other parts of the world.