Scientists work with vets and farmers to introduce New Sheep Scab Diagnostic Test

Sheep scab is caused by the mite Psoroptes ovis, is one of the most important ectoparasitic diseases of sheep in the UK and is a notifiable disease in Scotland. During the early stages of sheep scab infections are not obvious and animals often appear clinically normal. This subclinical stage can last for several weeks during which animals can act as a vector of infection. For control or eradication programs to be successful it is crucial that all infected animals are identified, including subclinical cases.

Scientists at Moredun have developed a diagnostic blood test which accurately detects sheep scab infestation in sheep, providing an important tool to aid in the diagnosis of the disease. The new test detects host antibodies specific to a recombinant antigen found only in the sheep scab mite which means that the test can accurately detect that an infection is due to the scab mite and not another ectoparasite. Moreover, the test can detect infected animals at a much earlier stage and before the onset of clinical symptoms which will be important in the control of this parasite.

Scientists from Moredun and SAC are now seeking the co-operation of farmers and vets in Scotland in order to integrate the results of this new blood test with skin scrapings taken from animals with suspected sheep scab infection. 

SAC currently provides veterinary surgeons in Scotland, with free ectoparasitic examinations of skin scrapings taken from sheep. It is hoped that integrating the results of the skin scrapings with this new blood test will provide a more powerful and reliable diagnostic service for sheep scab.

For this enhanced diagnosis, veterinary surgeons are asked to submit clotted blood samples (Vacutainer^®, red top) along with skin scraping samples from the same sheep to their local SAC Veterinary Services Disease Surveillance Centre (DSC). The serum samples will be then be forwarded to Moredun who will perform diagnostic serology free of charge. SAC will report the results of the diagnostic tests to the veterinary surgeon.

Dr Alasdair Nisbet who is leading the sheep scab research group at Moredun commented: “The development of a sensitive and specific blood test provides an important tool to aid control strategies for sheep scab. We appreciate the support of farmers and vets in submitting blood samples during this introductory phase, prior to the launch of the test for routine use at veterinary disease surveillance and investigation centres throughout the UK.”

Brian Hosie, Group Manager at SAC Veterinary services said: “SAC support the Scottish Government sheep scab control programme through diagnosis and reporting of cases of the disease. We welcome new diagnostic developments such as the Moredun test which will provide an additional tool to support our diagnostic efforts.”

The Sheep Scab (Scotland) Order 2010 states that flock owners or their veterinary surgeons must notify the authorities of any affected or suspect cases. SAC receives funding for disease surveillance from the Scottish Government Veterinary and Advisory Services programme.

For further information on Sheep Scab, please visit the Sheep Scab section on the SAC website.

Published on 19 March 2012 in Sustainability and Communities