Orf, or vuilbek as it is commonly known, is a highly contagious disease that occurs in sheep and goats. According to Dr Lindsay Parvess, CCS veterinarian with the Gauteng Department of Agriculture, the disease is caused by the parapox virus and mainly affects young animals. “Also take note that orf can be spread to humans. Therefore, care must be taken when working with affected animals. Wear gloves and wash your hands thoroughly after working with such an animal.”
Animals affected by orf will usually have blisters that will develop into crusty scabs on their nose or lips. These lesions extend into the mouth, affecting the dental pad and preventing proper mastication (chewing). “The blisters go on to burst and will then form the crusty scab. Orf is very painful for the animal and the pain will often prevent it from eating properly.” An animal that cannot eat will lose weight, will cease to produce wool and milk, and will eventually waste away if not supported. Severe cases lead to secondary skin and lung infections that have high treatment costs and can lead to the animal’s death, in spite of treatment. Lesions can also be found around the feet, around the udder where infected offspring are implicated, or even around the vulva of ewes who are mated by infected rams.
If the virus is present, the disease is easily spread in overcrowded situations. The disease is spread through injuries from thorns, wires and other sharp objects, and by damage from ticks and lice. “Considering how rapidly and easily the disease can spread, it is important to immediately separate any animals exhibiting signs of orf, to prevent it from spreading.”
When treating the separated animal, one must remember that it will experience pain and should therefore be carefully nursed. “Clean the affected regions with salt water. Make sure that the animals take in enough fluids and food. You can give teff or lucerne soaked in water or make use of pelleted feed. And don’t forget the clean drinking water!” With very severe cases, you must consult your local veterinarian. “If the animal is very sick and depressed and you see pus around the scabs, secondary infection may be present, and you will need to call in the vet.”
Remember that as a virus, orf cannot be treated with antibiotics, although the latter are often prescribed in cases of secondary bacterial infection. The most important part of treating infected animals, is symptomatic support through supplementary feeding and ensuring easy access to food and water. Vitamins can also be used to improve the immune system. The stronger the animal is when infected, the faster it will recover.
Currently, there is no stock of the commercial vaccine available, but an autogenous vaccine can be made by your veterinarian. This involves making use of the viral strain present on the farm. This vaccination is applied by scarification rather than the conventional injection, which should be done by someone who is familiar with the procedure, like a vet.
Proper herd management
Of course, prevention always remains better than cure. “Orf can be bestprevented by following good management practices,” says Dr Parvess. “This includesvaccination, not overstocking, making sure the camp and feed trough are free from sharp objects, and practising proper tick control.”
The virus is almost always brought in by a newly purchased infected animal, or exposure to one. Newly purchased animals should be isolated for at least two weeks before being introduced into the herd. If they show any signs of disease, they should be kept isolated and treated before joining the herd. The same applies to sick animals already introduced.
For more information, contact your MSD Animal Health representative or phone 011 923 9300.
Thank you for the support of several role-players in creating this series: the Gauteng Department of Agriculture and Rural Development, Dr Gillian Declercq and the CCS veterinarians (Dr Lindsay Parvess and Dr Heidi Kuhn), MSD Animal Health, as well as Kenneth Ndlovu and the Amogelang team for their assistance and animals for demonstration.