Scientific Opinion on BSE/TSE infectivity in small ruminant tissues

Abstract

The objectives addressed were i) to provide an update on TSE (Transmissible Spongiform Encephalopathy) infectivity distribution in small ruminant tissues; and ii) to indicate based on the current epidemiological situation as regards to BSE (Bovine Spongiform Encephalopathy) in the small ruminant population in the EU (European Union), whether a review of the existing SRM (Specified Risk Materials) list for small ruminants should be envisaged with regard to the potential exposure to the BSE agent. The appraisal was addressed by reviewing for Classical scrapie, BSE and Atypical scrapie in small ruminants aspects related to: i) tissue infectivity distribution according to the age and the genotype of sheep and goats; and ii) the infectious load in the different tissues. In order to perform the assessment all the currently available scientific results were reviewed, and data on TSE monitoring in small ruminants in the EU and on small ruminants slaughtered by species and age category in each EU Member State were considered. The reduction of the infectivity associated to the carcass of an infected individual achieved by the current SRM policy in small ruminants for Classical scrapie and BSE was estimated. The total number of Classical scrapie infected sheep and goats that could enter yearly into the food chain was provided. Moreover, considerations about Atypical scrapie were given. A set of simulations allowing estimating the impact of different policy options on the BSE infectious load potentially present in an infected sheep was provided.