Orf—also known as contagious pustular dermatitis, scabby mouth, or ecthyma contagiosum—is a highly contagious, zoonotic viral skin disease that primarily affects sheep and goats, and can occasionally be transmitted to humans. It remains a common challenge on farms around the world, especially during lambing season.
What Causes Orf?
Orf is caused by the orf virus, a member of the Parapoxvirus genus in the Poxviridae family. It is an epitheliotropic virus, meaning it targets skin cells and replicates in the host cell cytoplasm. The virus is robust and can survive for months in the environment, especially in dried scabs.
How Orf Spreads?
The virus spreads easily within flocks, particularly when animals experience minor skin trauma—for example, from rough grazing, thistles, or stubble. Young lambs and kids are the most susceptible, but adults can also be affected.
Transmission occurs through:
1. Direct contact with infected animals
2. Contaminated equipment, feeding bottles, bedding, or fence posts
3. Skin abrasions, which provide the virus with an entry route
Once established, Orf can rapidly circulate through a group, especially among orphan lambs sharing feeding equipment.
Recognising Orf in Sheep and Goats
In animals, Orf typically appears as:
Crusts and scabs around the mouth, lips, muzzle, and occasionally the teats or feet
- Wart-like proliferative lesions that may bleed when disturbed
- Reduced suckling in young animals, leading to weight loss and poor growth
- Painful teat lesions in ewes, which may lead to mastitis or refusal to feed young
Orf in Humans: What to Expect
Because Orf is zoonotic, humans can become infected—most often farmers, veterinarians, shearers, butchers, or anyone handling sheep or goats. If you contract orf it is important that you keep the area clean, dry and covered with antiseptic dressing to stop the spread.
Typical human symptoms include:
- A single red nodule on the hands or fingers
- Development of a pustule-like lesion, 2–5 cm in size
- Tenderness, swelling, and possible mild fever or lymph node enlargement
Complications
While most cases resolve naturally, complications can occur:
- Secondary bacterial infections
- Mastitis in ewes
- Failure to thrive in young animals due to painful lesions
- Rarely, more extensive lesions reaching internal tissues
Prevention: Reducing Orf on the Farm
Preventing Orf requires good hygiene, careful handling, and appropriate flock management techniques.
Key steps include:
- Regular cleaning of feeding equipment
- Managing pastures to reduce skin trauma
- Avoiding mixing of infected and clean groups
- Wearing protective gloves when handling affected animals
- Vaccinate against orf
Scabigard® – The Orf Vaccine
Scabigard is the only licensed Orf vaccine in the UK, designed to reduce clinical signs in flocks where Orf is already present. As a live vaccine, it must only be used in flocks with confirmed Orf, otherwise it can introduce the virus into a naive flock.
How Scabigard Works
Scabigard is administered via skin scarification—a scratch along the skin that deposits 0.02 ml of vaccine. This creates a controlled, mild local infection, producing a characteristic line of pustules known as the “vaccine take”. The scabs later fall off as immunity develops. This visible reaction is expected and confirms successful vaccination.
When to Vaccinate
Lambs: Can be vaccinated at any age from birth in at‑risk flocks.
Pregnant ewes: Vaccinate 7–8 weeks before lambing. Do not vaccinate less than 7 weeks pre‑lambing.
New stock: Any animals introduced into a flock with known Orf should be vaccinated before turnout.
Important Safety & Biosecurity Notes
- Scabs shed after vaccination contain live virus, so avoid contaminating the lambing area or housing.
- Always wear protective gloves, as the vaccine can infect humans.
- Check a small group of vaccinated sheep 7–10 days later to confirm “takes.”
Orf is a common but manageable condition. With good flock management, hygiene, and appropriate use of Scabigard farms can dramatically reduce the impact of this painful and economically costly disease. The use of an anti-microbial barrier gel such as Ambugreen by NoBACZ is a great way to prevent the spread once infection has already taken hold. Read our lates article on Ambugeen HERE. Awareness, prevention, and early recognition remain key to protecting both animals and farm workers.
If you have any questions or would like to discuss your flock health with us, please do not hesitate to give us a call on 01746 713911 or pop into our practice.
