Orf is an exanthemous disease caused by a parapox virus and occurring primarily in sheep and goats. It is also known as contagious pustular dermatitis, infectious labial dermatitis, ecthyma contagiosum, thistle disease and scabby mouth. Orf virus is zoonotic and can infect humans.
While orf is usually a benign self-limiting illness which resolves in 3-6 weeks. In the immunocompromised, it can be very progressive and even life-threatening. Serious damage may be inflicted on the eye if it is infected by orf, even among healthy individuals. The virus can survive in the soil for at least six months.
It has been reported from most sheep-or goat-raising areas including those in Europe, the Middle East, the United States, Africa, Asia, South America, Canada, New Zealand and Australia.
Orf is primarily a disease of sheep and goats although it has been reported as a natural disease in humans, steenbok and alpacas, chamois and tahr, reindeer, musk ox, dog, cat, mountain goat, bighorn sheep, dall sheep, and the red squirrel.