Orf with photoaggravated eruption

Abstract

EM: erythema multiforme PLE: polymorphic light eruption INTRODUCTION Orf could be seen as an occupational dermatosis among sheep farmers and shepherds. It is caused by a zoonotic DNA parapoxvirus transmitted to humans from sheep and goats. It resembles ‘‘Milker’s nodule’’ which is caused by another parapoxvirus infecting the teats of cows. Orf virus transmission occurs through inoculation of broken or abraded skineither by direct contact with affected animals or indirectly with contaminated fomites. The virus is resistant to drying and freezing and may remain viable on inanimate objects for months to years. Repeated outbreaks are normal, and larger case series from Norway and New Zealand have been published. In the United Kingdom, approximately 30% of shepherds reported previous infection with orf. A digital nodule presenting 3 to 7 days after inoculation is characteristic of orf. The lesion ulcerates, forms a dry crust, and resolves within 4 to 8 weeks. Its benign and self-limiting nature is known among most people handling sheep. There is a growing body of literature reporting systemic hypersensitivity reactions caused by orf virus. Such hypersensitivity reactions resemble cellmediated immune reactions seen in herpes simplex infections. Erythema multiforme (EM) is the most frequent and observed in 7% to 18%. Moreover, widespread papulovesicular eruptions and immunobullous dermatoses have been reported. Dermatologists should be aware of orf and the wide array of hypersensitivity reactions it can cause. Here, we describe 2 cases of orf with photoaggravated eruptions.