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From: TSS ()
Subject: UPDATE ON CHRONIC WASTING DISEASE (SEAC 93/2)
Date: October 4, 2006 at 9:09 am PST

4 October 2006 - The final minutes (154 KB) of the 93rd SEAC meeting held
on 6 July 2006 have been published.


SNIP...

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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