Orf. It is an odd-sounding word that seems like it should be an abbreviation or onomatopoeia, but it is purely English. Orf is a shortened version of the Old English word orfcwealm, meaning “livestock disease.” However, though it usually starts in livestock such as goats, sheep, alpacas, and cattle, it is transmitted to humans through farming and petting zoos.
Orf is caused by a parapox virus that causes soremouth or scabmouth in animals. Most often it affects sheep and goats, but can be found in any ruminant, including cattle and alpacas. It can also be found in dogs and cats. In animals, the virus creates sores around the mouth, nose, and eyes, and less commonly around other areas of the body. Orf can then spread to humans through contact with infected animals or fomites. Though it does not spread person to person, it can re infect the same individual.
Orf presents as superficial ulcerations and pustules, typically limited to the hands of affected people who have had direct contact with infected animals or fomites. The lesions can also be found elsewhere on the body, as the lesions can spread with exposure. Orf commonly will not have pain or systemic symptoms, though it can cause mild fever, swelling, or discomfort.
The differential for orf can be broad, but generally includes a variety of bacterial or viral causes. It can resemble bacterial ecthyma or cellulitis. Herpetic whitlow can also look similar to orf. Exposure history is most useful for diagnosis, as well as lack of other symptoms seen with bacterial or viral infections.
As a viral illness, orf will typically resolve on its own within 3 to 6 weeks. However, it can become progressive in individuals who are immunosuppressed. Cidofovir as a 1% topical treatment can be used for severe cases. The main concern with this disease is that the orf lesions can become secondarily infected.
Prevention of orf is very simple; avoid contact with infected animals and wash hands thoroughly after any animal contact or contact with potentially contaminated materials.
Written by Charles Glass, PA