Contagious ecthyma, also known as orf or contagious pustular dermatitis, can cause crusting scabs anywhere on the body. Lesions are most frequently seen on the lips, nose, eyelids, tongue, ear, udder, and mucous membranes of sheep. In humans, the disease usually causes a firm, painful nodule on the hands or fingers. This localized lesion usually persists for 1-4 weeks.

Contagious ecthyma is transmissible to humans by direct contact with a lesion or with a contaminated fomite (e.g., bedding, equipment, manure, feed).