Contagious ecthyma is a highly infectious viral disease of sheep and goats; common names for the same disease are orf and sore mouth. The bovine may be accidentally infected, but no other domestic livestock species is susceptible to the disease.
The disease occurs world-wide wherever sheep and goats are raised. It occurs primarily in lambs 3-6 months of age, but also may affect older sheep. Mortality is usually low, but may affect as much as 90% of the flock. Most human cases have histories of direct contact with infected animals.