Scrapie surveillance in Great Britain: results of an abattoir survey, 1997/98

Abstract

A randomised sample of 2,809 apparently healthy sheep, 55 per cent of them less than 15 months of age, which were slaughtered for human consumption at abattoirs in Great Britain in 1997/98, was taken to establish the prevalence of scrapie infection. The medulla oblongata of each sheep was examined histopathologically at the level of the obex, and fresh brain tissue was examined for scrapie-associated fibrils (SAF) to establish whether there was evidence of scrapie. In addition, histological sections of the medulla from 500 of the sheep were immunostained with an antiserum to PrP, and the same technique was also applied to any animal found positive or inconclusive by the histological or SAF examinations. Any sheep which was positive by any of these diagnostic methods was also examined by Western immunoblotting, for the detection of the disease-specific protein PrP(Sc). A total of 2,798 sheep (99.6 per cent) were negative by all the methods applied. Ten animals were SAF-positive but negative by all the other methods, and in one animal there was immunohistochemical staining which could not be interpreted unequivocally as disease-specific. A mathematical model was used to estimate the prevalence of scrapie infection in the national slaughtered sheep population which would be consistent with these results. By this model, the absence of unequivocally substantiated cases of scrapie in the sample was consistent with a prevalence of infection in the slaughter population of up to 11 per cent.

A descriptive study of the prevalence of atypical and classical scrapie in sheep in 20 European countries

“…This extends previous studies on scrapie prevalence in Europe which have either been limited to one region or country [36-39] or have not discriminated between CS and AS [40,41]. …”

Prevalence of scrapie infection in Great Britain: interpreting the results of the 1997–1998 abattoir survey

“…The prevalence of infection in on October 14, 2014 rspb.royalsocietypublishing.org Downloaded from (table 1) is also computed using equation (3.3), which assumes that the ages of the animals sampled are uniformly distributed within the age class. This is reasonable because animals were sampled throughout the year (Simmons et al 2000;cf. Webb et al 2001).…”

Prevalence of sheep infected with classical scrapie in Great Britain, 1993–2007

“…Although scrapie surveillance data have been collected from multiple sources and over a number of years, most previous estimates of scrapie prevalence have been based on data collected during a single year, often utilizing only a single source of surveillance data [3][4][5][6][7][8]. However, there are problems associated with estimating prevalence from a single source of data.…”