The viruses in this group are sometimes referred to the family Asfarviridae.
In Africa, warthogs and their associated ticks [Ornithodoros moubata porcinus] are the reservoir of disease, although the infection is not clinical in warthogs. Outbreaks occur when domestic pigs come in contact with the ticks, rather than from direct transmission from other pigs or warthogs. In Europe, direct transmission is more important as the virus is shed in high concentration in excretions and secretions during the acute phase. Ticks [Ornithodoros erraticus] on the Iberian peninsula can also be a source of infection.