NR AWCE
AU Birch,C.P.D.; del Rio Vilas,V.J.; McDonald,R.; Chikukwa,A.
TI The distribution of sheep sampled for scrapie in Great Britain
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Poster sessions EPI-01
PT Konferenz-Poster
AB Estimates of the prevalence of scrapie in Europe depended until recently on mandatory reports of clinical cases in adult animals. This method of surveillance was suspected of underestimating the true prevalence, because the denominator population was unknown. Therefore the denominator populations of the active surveillance methods established since 2002 in Great Britain should be identified. Sheep in the abattoir, fallen stock and dead in transit surveys are sampled after being transported to a limited number of locations. Therefore geospatial biases can be expected in these surveys. Holdings providing sheep to the fallen stock survey were identified and located from County-Parish-Holding (CPH) numbers. The holdings providing sheep to the abattoir and dead in transit surveys were identified from the flock tags recorded from sampled sheep, by tracing back to source premises recorded in the Animal Movement Licensing Scheme (AMLS) database. Over 90% of the holdings associated with sampled sheep could be traced (c. 2000 out of 2160 holdings in the fallen stock survey 2005, c. 5500 out of 6047 in the abattoir survey). All the surveys sampled Great Britain unevenly, with different regional biases. The abattoir survey sampled western regions most intensely, especially Wales, whereas the fallen stock survey was most intense to the east. Both surveys sampled the Highlands and Islands of Scotland and the south-east of England sparsely. Differences between the geospatial distributions of samples in the surveys were associated with differences in the characteristics of holdings sampled, including numbers of sheep. The impact of these uneven spatial distributions on surveillance will depend on the relationship between the pattern of sampling and the distributions of scrapie infection and PrP genotypes.
AD Centre for Epidemiology and Risk Analysis, Veterinary Laboratories Agency, Weybridge, UK. E-mail: c.birch@vla.defra.gsi.gov.uk
SP englisch
PO Italien