Scientists and vets at Moredun Research Institute and Biobest Laboratories Ltd have developed and evaluated a diagnostic test on nasal swabs from thin ewes that could be used to screen flocks for Ovine Pulmonary Adenocarcinoma (OPA). The study was funded by the Agriculture and Horticulture Development Board (AHDB), Hybu Cig Cymru (HCC), Northern Ireland Agricultural Research and Development Council (AgriSearch) and Biobest Laboratories Ltd, with some support from the Animal and Plant Health Agency (APHA).
Ovine Pulmonary Adenocarcinoma, also known as Jaagsiekte, is an infectious lung tumour caused by a virus that affects sheep. There is no treatment or vaccine and once clinical signs appear the disease is invariably fatal. Affected flocks may lose as many as 20 per cent of stock in the first few years that OPA is seen, and the disease may continue to account for the loss of a few per cent of sheep every year for many years thereafter. The disease appears to be increasingly common throughout the UK and the ability to identify flocks carrying OPA is required, however currently there is no means to do this.
A test that would allow producers to determine whether their flock is infected would be advantageous in two ways. It would enable farmers to identify if the infection is present in their flock and take control measures to minimise losses. Perhaps more importantly, the 70 – 90% of flocks that are estimated to be free of the disease would be able to buy replacement breeding stock from flocks deemed to have a low risk of being infected with OPA.
In this pilot study the new test on nasal swabs from thin ewes was evaluated in a small number of flocks and was shown to detect the virus only in flocks that were affected. The virus was not detected in any of the flocks that were free of disease.
As a flock test based on sampling thin ewes, this could be used to identify low-risk flocks and facilitate an OPA assurance scheme.
Further validation of the test is planned, in addition to engagement with stakeholders to determine how a robust and cost-effective assurance scheme can be developed.