Vetnews | Oktober 2024 36 « BACK TO CONTENTS Sheep scab is one of the oldest sheep diseases known to mankind. It was presumably introduced into South Africa by the Settlers and has been a known problem since the 17th century. It became a regulated disease in South Africa in 1693 when Simon van der Stel promulgated regulations to prevent its spread1. It is a highly contagious disease that can have detrimental effects on the health and well-being of affected sheep. It has a potentially significant economic impact on sheep farmers due to international trade implications, especially for the wool industry; loss of body condition and production losses; and the cost of treatment. Sheep control falls under the Animal Diseases Act2 and its Regulations. The basics of sheep scab Sheep scab is caused by Psorpotes ovis. The mites feed on the skin of the animals where they cause an intense inflammatory reaction with severe itching. This causes the sheep to scratch and bite themselves, leading to hair- and wool loss and self-trauma. Sheep typically present with matted, deranged or stringy wool. They often have yellow papules and develop coagulated exudation on the skin. In extreme cases, the disease can even lead to death of the animals. The mites have a life cycle of about two weeks from hatching to laying eggs again. They can survive off the host in the environment for up to three weeks. This is important to remember when treating infected sheep and managing the spread of the disease. Goats are also listed as a susceptible species. Although they do not usually develop clinical disease, the mites can survive on goats, and they can act as a reservoir for the disease. General Control Measures Sheep scab is a listed controlled disease in terms of the Animal Diseases Act. All the general control measures are applicable. This includes the owner’s duty to report it, to take measures to prevent the animal from becoming infected and to prevent the spread of the disease once animals have been infected. These duties are set out in Section 11 of the Animal Diseases Act. Veterinarians must note that Section 11(2) of the Animal Disease Act places a duty on them to report the incidence or suspected incidence of a controlled disease to the relevant State Veterinarian. The manner in which a controlled disease must be reported is set out in Regulation 12 of the Animal Diseases Regulations published in terms of the Animal Diseases Act. Failure to report could potentially result in criminal prosecution. Another general control measure that is very relevant in the case of a sheep scab outbreak, is the isolation of the infected and contact animals. For sheep scab, this generally means all the sheep and goats on the farm and may include the sheep and goats on other farms of the same owner. Specific Control Measure for Sheep Scab Routine preventative measures for susceptible animals: Table 2 of the Regulations stipulates that sheep moved to a farmer’s land must be treated twice with an effective remedy before they are allowed to mix with other sheep on the farm. The required interval between the two treatments is not stipulated in the Regulation. Based on the two-week life cycle of the mites, the second treatment should be between 7 to 10 days after the first treatment. This ensures that if there are still eggs that hatch after the first treatment, the mites will be killed before they lay eggs again. Suspected outbreaks: The responsible State Veterinarian must be notified as soon as possible of any suspected outbreak of sheep scab. It is important to note that the Regulations also make it compulsory to report Legal Mews SHEEP SCAB CONTROL: NAVIGATING VETERINARIANS’ RESPONSIBILITIES Trudie Prinsloo (Legalvet Services) This article is intended to provide information and educate veterinarians on relevant aspects of the law. It is not intended as personal legal advice. SAVA is not responsible or liable for any advice or other information provided herein.
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