ecthyma

(medicine) An inflammatory skin disease characterized by large flat pustules that ulcerate and become crusted, and are surrounded by a distinct inflammatory areola.

A pyogenic infection of the skin due to staphylococci or streptococci and characterized by adherent crusts beneath which ulceration occurs.

A shallowly eruptive form of impetigo.

• contagious e. — a specific dermatitis of sheep caused by a poxvirus in the genus Parapoxvirus. The virus is strongly antigenic and an attack of the disease or vaccination provides long-lasting immunity. If the flock has previously been exposed the disease is restricted in occurrence to lambs and young sheep. The characteristic lesions occur mostly on the lips and the skin around the mouth, but have appeared wherever skin contact has been made with a source of infective virus, e.g. ear tagging, tail docking. Lesions are first papules, then crusts, and finally discrete thick tenacious scabs over vigorous granulation tissue. Very young lambs develop an extensive form of the disease involving even the alimentary tract. Occasional older sheep also have extensive lesions on other skin areas such as the coronets, and at the other mucocutaneous junctions. The disease is transmissible to humans. Called also orf, scabby mouth, contagious pustular dermatitis.