Coordinated control of sheep scab across the four nations of the UK

Sheep scab is caused by infestation with the ectoparasitic mite, Psoroptes ovis. The disease is highly contagious, resulting in intense pruritus and represents a significant welfare and economic concern. Recent estimates of the financial impact of sheep scab on the UK sheep industry indicate that the cost of scab is between £80-200m per annum. Scab was previously eradicated from the UK but was, unfortunately, re-introduced with imported animals in 1973. Since then, scab has become endemic in the UK, with estimated 8-10k cases yearly and is particularly prevalent in hill and upland areas and especially in areas of common grazing. Control of scab is through macrocyclic lactone (ML) injectables and organophosphate (OP) plunge dipping. However, mites resistant to the MLs have been identified in the UK, highlighting the importance of using the remaining chemicals in a sustainable manner in the future to preserve their efficacy. As scab can spread very easily between farms, especially those sharing common grazing, coordinating control efforts is crucial to ensure that outbreaks are dealt with effectively. The development of a blood test (ELISA) for the specific and sensitive diagnosis of sheep scab, before the appearance of clinical signs provides a significant boost to the control of scab. Moredun has been leading control efforts in this area over the last 2-3 years, with control programmes utilising the blood test in all four nations of the UK currently underway, including schemes in England, Scotland, Northern Ireland & Wales. These schemes have demonstrated that coordinated efforts can achieve lasting control of sheep scab, providing important exemplars of how future control of sheep scab and other endemic diseases of sheep may look in the future.