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works in infested areas where the virus may be harbored on fences, feeding basins, and other surfaces in the
livestock areas. Human-to-human infection does not occur.
Subjective: Symptoms
One usually reports a history of contact with ungulates (sheep, goats, yaks), or cattle. After a 5 to 7 day
incubation period one notes pruritus in an abraded area. This lesion enlarges and becomes painful. One may
note systemic complaints of fever and chills on occasion.
Objective: Signs
Using Basic Tools: In Milker’s nodule primary lesion is a deep erythematous papule (or small group of papules
that enlarges) gradually into a firm, smooth, hemispherical nodule varying in size up to 2 cm in diameter. As with
other viral processes the lesions usually become umbilicated. In human orf infections (HO) there are six classic
clinical stages of the usually solitary lesion that last approximately 1 week; erythematous papular stage, targetoid
plaque with central crusting, tender nodular, acute weeping nodular stage, regenerative stage, and regressive
stage that heals without scaring. An ascending regional lymphangitis may be observed. The most common
location is the dorsum of the index finger on the dominant hand due to handling the livestock or items within the
livestock area. Other exposed skin sites of the arm, face, and leg are also at risk of infection.
Assessment:
Diagnosis based on clinical morphologic criteria and history of exposure to infected bovine or ungulate livestock
or livestock areas.
Differential Diagnosis
Erysipelas, erysipeloid, atypical mycobacterium, bacillary angiomatosis, cat-scratch disease, leishmaniasis,
pyogenic granuloma.
Plan:
Treatment
Primary: Symptomatic treatment for pain and pruritus.
Alternative: Antibiotic for secondary wound infections.
Patient Education
General: There are no effective vaccines for Milker’s nodules or human orf available for livestock. The highest
risk of HO is in workers slaughtering sheep, infecting approximately 5% on workers. Spontaneous, non-scaring,
healing occurs generally in 4 to 6 weeks.
Prevention and Hygiene: Keep wounds clean and covered to aid in healing and decrease secondary infection.
No Improvement/Deterioration: Referral for biopsy and histological confirmation of process.
Follow-up Actions
Reevaluation: Refer for biopsy and histological confirmation of diagnosis.
Evacuation/Consultation Criteria: Evacuation not necessary. Consult as needed.
Zoonotic Disease Considerations
Contagious Ecthyma (Orf)
Agent: Orf virus (Parapox)
Principal Animal Hosts: Sheep, goats
Clinical Disease in Animals: Lesions on skin of lips and oral mucosa of lambs; udders of nursing ewes
Probable Mode of Transmission: Occupational exposure
Known Distribution: Worldwide; common