Case Presentation: A 38-year-old female with a past medical history of non-insulin dependent type 2 diabetes, HSV-2, and vitamin D deficiency presented to the emergency department for evaluation of a finger lesion. It was located on her left lateral index finger near the PIP joint with associated growth and scant drainage over the last two weeks. She was diagnosed with presumed wart and surrounding cellulitis, and was discharged with Keflex. During outpatient follow-up, she denied any exposure to animals and systemic symptoms. Due to rapid spread of the rash in a short time period, referral was placed to dermatology, who felt the lesion was Orf virus versus Poxviridae, HSV, or superficial bacterial infection. Wound cultures were obtained while bacterial cultures and HSV PCR were negative. PCR test for Orf virus was not readily available and could not be performed. She represented to ED two days later for worsening diffuse swelling and pain. The patient recalls slaughtering sheep for Eid celebration in July. One day later, she presented as an outpatient secondary to multiple painful red and white rashes that had spread to bilateral palms, soles, and extremities. She was noted to have polyarthralgias and a blanching, diffuse maculopapular rash. A diagnosis of erythema multiforme was made and she was initiated on a 3-week prednisone taper and Claritin. The rash resolved after treatment with steroids.
Discussion: Orf virus inoculates humans through broken skin from infected animal lesions, with associated lesions appearing 3-7 days later (1). Progression goes from a papule to a weeping target lesion to an ulcer (7-14 days) that dries out and resolves in 4-6 weeks (1,3). It is predominantly seen in areas that have high populations of sheep and goat (1,2,3). Orf virus is generally benign but can have rare complications including but not limited to lymphadenopathy, erythema multiforme. Orf-associated EM develops 2-4 weeks after primary orf lesions with characteristic symmetric papules, macules, and target lesions that can be diffuse in nature (1). Populations that are most aware of orf virus include farmers, veterinarians, and shepherds who work closely with these animals for a living.
Conclusions: This case highlights the need for awareness of Orf virus amongst religious populations who are more likely to be exposed to sheep and goat. Additionally, it highlights the importance of a thorough exposure history and cultural considerations in developing a differential diagnosis for a new rash.