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From: TSS ()
4 October 2006 - The final minutes (154 KB) of the 93rd SEAC meeting held ITEM 4 – UPDATE ON CHRONIC WASTING DISEASE (SEAC 93/2) 11. The Chair reminded members that at SEAC 85 (November 2004) the committee had discussed the human and animal health implications of Chronic Wasting Disease (CWD) in the UK and Europe. The main conclusions were that: • there was no evidence that CWD or BSE is present in the UK cervid population, however a low prevalence could not be ruled out. • there was no evidence that CWD is transmissible to humans from consumption of venison or to cattle, sheep or goats through non-experimental means. • CWD poses relatively little risk to human health but as a risk cannot be entirely excluded a watching brief should be maintained. 3 Baron et al. (2006) Transmission of new bovine prion to mice. Emerging. Infect. Diseases. 12, 1125-1128. 7 © SEAC 2006 12. As part of the watching brief, the SEAC secretariat had produced a review of the new information on CWD published since October 2004. The new data suggest that: • more than one strain of CWD may exist. • the geographic distribution of CWD in cervids in North America may be increasing, although CWD has not been identified in surveys carried out elsewhere in the world. • the natural host range of CWD has broadened to include the moose. • although CWD has been transmitted to cattle after ic inoculation, cattle orally inoculated with CWD have shown no signs of infection after seven years. • CWD has been transmitted to non human primates but not to humanised mice by ic inoculation. • CWD may be transmitted through contaminated soils. • CWD infectivity has been found in the muscle of mule deer. 13. Mr Patrick Burke (Defra) explained that a European Union (EU) wide surveillance programme for TSEs in red deer and white tailed deer was intended to commence in Autumn 2006. The survey will include deer over 18 months old from five groups (i) animals that show clinical signs of disease, (ii) animals involved in road traffic accidents, (iii) fallen stock, (iv) culled deer and (v) healthy farmed/wild deer shot for human consumption. Male wild deer will be targeted as North American data suggest an increased prevalence of infection in male animals. Older farmed deer will also be targeted due to the increased probability of exposure to contaminated feed. Areas with a high historic or present incidence of BSE or scrapie or a high potential for historic consumption of BSE contaminated feed will also be targeted. Areas that received imports of deer from North America will also be targeted, although this does not apply to the UK. UK surveillance will be conducted over an 18 month period and will include 598 wild and 598 farmed deer. The committee asked how the numbers for the surveillance study were derived. Professor John Wilesmith (Defra) stated that the numbers were derived by the European Food Safety Authority (EFSA) expert group to enable detection of a certain prevalence of TSE infection4. 14. Members asked if experiments had been conducted to mimic natural transmission of CWD by continuously feeding cattle infectious material. Nobody was aware of such a study which 4 Information provided by Defra after SEAC 93: the numbers of deer selected enable detection of a prevalence of TSE infection in deer of ≥��� 0.5%. 8 © SEAC 2006 could be useful. It was noted that a study of cattle grazing in CWD endemic areas was ongoing but no transmissions had been observed. 15. A member asked if experiments have examined the susceptibility of European red deer to CWD. Dr Matthews stated that a study in the USA was examining the transmissibility of CWD to red deer but was of low priority as it is a minority species in North America. No such study is being conducted in the UK. 16. The committee noted that deer killed in road traffic accidents (RTA) may be a good source of material for TSE surveys as evidence from North America suggests such animals are more likely to be diseased. In addition, the annual culling of elderly sick deer in the Scottish Highlands may also be a good source of animals for TSE surveys. Research into the logistics of taking samples from deer in remote areas had been conducted that would aid the design of a survey. Dr Matthews noted that use of deer killed in RTAs is being considered but many animals would only be found several days after death reducing the quality of the samples that could be obtained. A member noted that much of the North American surveillance data was based on hunter killed asymptomatic animals. 17. A committee member asked about the age of the animals at the time of inoculation of CWD in the study using non-human primates. Dr Darren Cutts (SEAC secretariat) stated that the authors described the animals as adult when inoculated but a precise age of inoculation had not been stated. 18. The committee agreed with all the suggested changes made to the position statement in light of the new information as outlined in Annex 3 of SEAC paper 93/2 with minor grammatical changes. In addition, it was agreed the statement should include comments that distinct differences in the neuropathological phenotype had been found between the appearance of CWD and BSE in cattle and to clarify the number of humanised mouse strains inoculated with CWD in the transmission study cited. 19. The Chair commented that, although there was no evidence that CWD was a human health risk, a watching brief should be maintained. The Chair thanked Dr Cutts for surveying the literature and producing the paper. The updated statement would be placed on the SEAC website. snip... http://www.seac.gov.uk/minutes/final93.pdf TSS
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