Erythema multiforme after orf virus infection: a report of two cases and literature review

Abstract

Orf virus has a worldwide distribution among sheep and goats. The hypersensitivity reaction erythema multiforme (EM) is a known complication of orf infection in humans; however, its occurrence is poorly understood and has not been extensively reviewed. We present two unrelated cases of orf-associated EM, and a review of the literature, highlighting important clinical, epidemiological and immunological aspects of this condition. Orf and its associated complications can occur in rural areas, as well as urban settings, where it is less well-known, through religious or cultural practices involving animal slaughter. Obtaining a history of animal exposures from patients with lesions suspicious for orf and secondary skin eruptions can guide diagnosis and identification of the inciting immune stimulus. Determining the pathophysiology and relative contribution of host and viral factors contributing to EM and other orf-associated hypersensitivity reactions could facilitate the identification of risk factors and inform treatment decisions.

Fig. 1

[colour online]. Primary lesion on the left index finger. Orf virus DNA was detected in a dry swab of this lesion.

Fig. 2

[colour online]. Vesicular eruption observed ~2 weeks after onset of primary orf lesion.

Fig. 3

[colour online]. Coallescing targetoid lesions observed ~3 weeks after onset of primary orf lesion.

Fig. 4

[colour online]. Blister on right thumb. Orf virus DNA was detected in a dry swab and roof sample of this lesion.

Fig. 5

[colour online]. Maculopapular rash observed 2 weeks after onset of the primary orf lesion.