Evaluation of the application of Sweden to be recognised as having a negligible risk of classical scrapie
Sweden submitted a request to the European Commission to be recognised as a Member State with negligible risk of classical scrapie. EFSA has been asked to assess if Sweden in its application has demonstrated for a period of at least seven years proposed/in the future, that a sufficient number of ovine and caprine animals over 18 months of age, representative of slaughtered, culled or found dead on farm animals, have been tested annually, to provide a 95% level of confidence of detecting classical scrapie if it is present in that population at a prevalence rate exceeding 0.1%. A risk-based approach using scenario-tree modelling with stochastic simulations was applied. There is lack of data on the actual performance of the approved tests in field conditions, especially in sheep. Alternative scenarios were explored extending the range from the sensitivity provided by the past European Union evaluations of screening diagnostic tests to a sensitivity of 50%, consistent with published data obtained under field conditions in infected goat populations. Using data provided by Sweden in its application, the estimated parameters of the scenario-tree model and the range of values of sensitivity, it is concluded that Sweden has tested annually a sufficient number of small ruminants to meet the requirement. Based on the expected number of samples to be tested in 2015 and future years, Sweden would test a sufficient number of animals to meet the requirement if the actual test sensitivity under field conditions was higher than 80%. It is recommended that specific analytical approaches should be agreed upon for use by other MS when preparing their applications for the recognition of the negligible risk of classical scrapie, and that data on the sensitivity of screening diagnostic tests in field conditions should be generated where possible.