Burgess, S., Innocent, G.T., Nunn, F., Frew, D., Kenyon, F., Nisbet, A.J. and Huntley, J.F.
||Sheep scab is a highly contagious disease of sheep caused by the ectoparasitic mite Psoroptes ovis. The disease is endemic in the UK and has significant economic impact through its effects on animal performance and welfare. Successful treatment relies on chemical intervention however concerns over the sustainability of these treatments due to their environmental and health implications, combined with an increase in drug resistance shows a clear need for alternative methods of disease control. Diagnosis of sheep scab is achieved through the observation of clinical signs e.g. itching, pruritis and wool loss and ultimately through the detection of mites in skin scrapings. Early stages of infestation are often difficult to diagnose and sub-clinical animals can be a major factor in the spread of disease. The development of a diagnostic assay would enable farmers and veterinarians to detect disease at an early stage, reducing the risk of developing clinical disease and of spreading to other flocks. This paper describes the further validation of a sheep scab specific diagnostic ELISA based on a single recombinant antigen. Sera samples were obtained from an outbreak of sheep scab within an experimental flock, which allowed the assessment of sheep scab specific antibody prior to infestation, mid-outbreak (combined with clinical assessment of all animals) and post-treatment. The results further demonstrate that the ELISA can effectively diagnose sheep scab in a natural outbreak of disease and more importantly highlight its ability to detect sub-clinically infested animals. This ELISA, employing a single recombinant antigen, represents a major step forward in the diagnosis of sheep scab and will prove to be critical in any future control or eradication program.