Research article
A descriptive study of the prevalence of atypical and classical scrapie in sheep in 20 European countries
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* Corresponding author: Alexandre Fediaevsky a.fediaevsky@lyon.afssa.fr
1 AFSSA-Lyon, Unité Epidémiologie, 31 Avenue Tony Garnier, 69364 Lyon Cedex 07, France
2 INRA, UR 346 Epidémiologie animale, 63 122 Saint Genès Champanelle, France
3 CERA, VLA Weybridge, Woodham Lane, New Haw, Addlestone, Surrey, UK. KT15 3NB
4 SVA, National Veterinary Institute, 751 89 Uppsala, Sweden
5 CEA-Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Italy
6 National Veterinary Institute, P.O. Box 750 Sentrum, 0106 Oslo, Norway
BMC Veterinary Research 2008, 4:19 doi:10.1186/1746-6148-4-19
Published: 10 June 2008Abstract
Background
The development of active surveillance programmes for transmissible spongiform encephalopathies of small ruminants across Europe has led to the recent identification of a previously undetected form of ovine prion disease, 'atypical' scrapie. Knowledge of the epidemiology of this disease is still limited, as is whether it represents a risk for animal and/or public health.
The detection of atypical scrapie has been related to the use of only some of the EU agreed rapid tests. Information about the rapid tests used is not, as yet, available from public reports on the surveillance of transmissible spongiform encephalopathies in small ruminants. We collected detailed results of active surveillance from European countries to estimate and to compare the prevalence of atypical scrapie and classical scrapie in sheep for each country stratified by each surveillance stream; healthy slaughtered and found dead adult sheep.
Results
From the 20 participating countries, it appeared that atypical scrapie was detected in Europe wherever the conditions necessary for its diagnosis were present. In most countries, atypical scrapie and classical scrapie occurred at low prevalence level. The classical scrapie prevalence estimates were more variable than those for atypical scrapie, which appeared remarkably homogeneous across countries, surveillance streams and calendar years of surveillance. Differences were observed in the age and genotype of atypical scrapie and classical scrapie cases that are consistent with previous published findings.
Conclusion
This work suggests that atypical scrapie is not rare compared to classical scrapie. The homogeneity of its prevalence, whatever the country, stream of surveillance or year of detection, contrasts with the epidemiological pattern of classical scrapie. This suggests that the aetiology of atypical scrapie differs from that of classical scrapie.