Rapid improvement of human orf (ecthyma contagiosum) with topical imiquimod cream: report of four complicated cases

Orf is a zoonosis caused by an epitheliotropic DNA parapox virus. Human orf is a generally benign, self-limiting condition that usually regresses in 6-8 weeks without specific treatment. However, it may be accompanied by local symptoms including pain, pruritus, lymphangitis and axillary adenitis, or less frequently by systemic symptoms such as fever or malaise. Furthermore, it may be complicated by erythema multiforme, Stevens-Johnson syndrome, erysipelas, generalized mucocutaneous eruption, toxic erythema, eyelid oedema and giant, persistent or recurrent lesions in immunocompromised patients. Imiquimod, a potent topical immune response modifier, enhances both the innate and acquired immunity by stimulation of immune system cells resulting in local antiviral, antitumour and immunoregulatory activity. We present, for the first time, four complicated cases of orf successfully treated by topical imiquimod resulting in rapid regression of both orf and associated lesions. Two of the cases were complicated with erythema multiforme, one with recurrent eyelid oedema, and another had giant orf associated with axillary lymphadenitis. We suggest that topical imiquimod may be an effective and safe therapy for complicated orf cases.