Ecthyma Contagiosum (Orf)

Comments:
Ecthyma contagiosum (Orf, contagious pustular dermatoses, scabby mouth) is a zoonotic disease caused by a DNA parapoxvirus. It primarily infects sheep and goats in which it causes pustules of lips and perioral areas.

Transmission to humans (usually sheep-handlers) occurs by direct inoculation from infected lesions or contact with contaminated objects such as fences and farm tools.

After an incubation period of 5-6 days, a solitary lesion develops usually on hand or forearm and rarely on face. Initially, it is a small, firm, red-blue papule which develops into a 2-5 cm size hemorrhagic blister or pustule. The fleshy, red appearance of the lesion may be mistaken for lobular capillary hemangioma or keratoacanthoma. There is associated itching and tenderness. The patient may develop low-grade fever and lymphadenitis. Superimposed pseudomonas aeruginosa infection may occur.

The lesion resolves spontaneously without scarring in about 3 weeks. Immunocompromised patients may develop multiple, large lesions that may not heal spontaneously and be resistant to treatment.