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From: TSS ()
Subject: Re: SEAC 93rd MEETING ON THURSDAY 6TH JULY 2006 'AGENDA' (cwd)
Date: July 11, 2006 at 8:52 am PST

11 July 2006 - A Summary (84 KB) of the 93rd SEAC meeting held on the 6th July 2006 has been published.

The final minutes (94 KB) of the 92nd SEAC meeting held on 28th April 2006 have also been published.


The Spongiform Encephalopathy Advisory Committee held its 93rd meeting in London on 6th July 2006 and discussed the following matters: CURRENT ISSUES SEAC was informed about the following issues: • Publication of the Defra response to the independent review of the origins of BSE cases born after the reinforced feed ban (BARB cases) by Professor William Hill1. • A consultation on draft guidance on how to best manage the risks of transmission of CJD and vCJD via surgical procedures produced by the CJD Advisory Committee of the National Institute for Health and Clinical Excellence2. • The first meeting of the Clinical Governance Advisory Group, an independent group recently convened to advise DH on the appropriate counselling and care for individuals defined as ‘at risk from vCJD for public health purposes’. • An update from the Health Protection Agency on convening an expert group to consider post mortem testing as a means of obtaining better data on the prevalence, age and genotype distribution of vCJD in the UK population, as recommended by SEAC3. The committee urged that this group be set up
1 http://defraweb/animalh/bse/pdf/hill-response_annex1.pdf2
© SEAC 2006
without delay as it is of utmost importance that better estimates of the prevalence of vCJD infection be obtained. • The SEAC Chair and Deputy Chair had briefed the FSA Board in relation to its recent discussions on atypical scrapie and BSE in sheep4. As the human health implications of atypical scrapie are unknown, SEAC suggested it would be timely for the National CJD Surveillance Unit to remind neurologists to remain vigilant and refer unusual neurological cases to the Unit. • Reports that TSE tests on a small number of predominantly older cattle in Europe and the USA suggest that other forms of spongiform encephalopathy may occur in some cattle. CHRONIC WASTING DISEASE IN UK DEER SEAC considered new research published since its position statement, published in November 2004, on the possible public and animal health implications of chronic wasting disease (CWD) in UK deer. Although the geographical distribution of CWD in North America was apparently expanding and the natural host range had widened, this may just reflect expansion of surveillance programmes. There was however, no evidence of CWD being present in deer in the UK or elsewhere in Europe. As surveillance data are limited, EU plans for further TSE testing of deer were welcomed. New data on transmission of the TSE agent when bound to soil strengthened the evidence for environmental transmission of CWD. Although cattle intracerebrally (ic) inoculated with CWD showed clinical signs, no transmissions had been observed after more than 7 years in an ongoing study of cattle orally inoculated with CWD, suggesting a barrier exists to transmission to cattle by natural means. Although CWD has been transmitted to non-human primates by ic inoculation, it was not transmitted to humanised mice via this route, suggesting some barrier for transmission to humans may exist. Infectivity has been detected at low levels in muscle of deer infected with CWD.
© SEAC 2006
In light of the new information, SEAC amended its position statement but agreed that CWD currently poses relatively little risk to human health, or to the health of cattle, sheep or goats in the UK. Nevertheless, as a risk cannot be excluded, a watching brief should be maintained. ASSESSMENT OF FEED SUPPLY ROUTES At SEAC 87, SEAC endorsed a recommendation from the SEAC ad hoc Epidemiology Subgroup on UK BARB5 BSE cases that Defra perform an evaluation of current and recent animal feed use and supply routes. Defra presented its evaluation of the animal feed use and supply network for comment. SEAC welcomed the comprehensive report noting that feed assurance schemes, surveillance and controls in place substantially reduce the risk of contamination of feed with mammalian meat and bone meal (MMBM). SEAC emphasised the need to maintain awareness, to continue effective enforcement of the controls and to refine the specificity of tests for MMBM in feed. EU TSE ROADMAP Defra and FSA asked SEAC to comment on their proposals to seek the committee’s advice on issues arising from the European Commission TSE Roadmap6 setting out possible changes to TSE control and surveillance measures. SEAC generally agreed with the proposals but considered that it would be important for the departments to review their proposals and seek advice from SEAC in light of emerging data. As the European Food Standards Authority (EFSA) will consider a number of the issues, opportunities may arise for SEAC to feed into these deliberations. METHODS TO EVALUATE NEW SURGICAL INSTRUMENT DECONTAMINATION TECHNOLOGIES The Engineering and Science Advisory Committee into the decontamination of surgical instruments including prion removal
5 Born after the reinforced feed ban of July 1996 6 3
© SEAC 2006
asked SEAC to advise on scientific principles to consider in relation to the evaluation of new TSE decontamination technologies. SEAC endorsed the need for independent evaluation of the efficiency and reliability of new decontamination technologies prior to implementation. It emphasised that evaluation methods should allow reductions in decontamination to be quantified and the efficacy of different decontamination methods to be compared. It is essential that the effect of decontamination treatments on TSE infectivity, not just prion or other protein levels, be evaluated. As the resistance of TSE strains to decontamination treatments is likely to differ, the effect on human or closely related TSE strains should be assessed. The committee agreed to produce a statement on its consideration. AOB - TSE NOMENCLATURE SEAC noted that use of the terms “atypical scrapie” in sheep, and more recently, “atypical BSE” in cattle to describe emerging conditions in sheep and cattle causes confusion over the nature disease agent involved, and the risk to consumers. The committee agreed that reclassification of atypical scrapie may cause more confusion as the term had been in use for some time. However, it is important to clarify that, in contrast to classical scrapie, which appears benign, the human health implications of atypical scrapie are unknown. The committee agreed that the use of the term “atypical BSE” in cattle should be discouraged. BSE STUDIES IN CATTLE SEAC considered the findings of three studies to examine (i) the relationship between the oral dose of BSE and the incubation period and attack rate in cattle, (ii) the relationship between the time of first detection of PrPSc in the central nervous system (CNS) and the incubation period following oral challenge of cattle with BSE and (iii) the distribution of abnormal prion protein (PrPSc) in certain peripheral nervous system (PNS) tissues of cattle at the preclinical and clinical stage of BSE infection. The item was discussed in a reserved business session in accordance with the
© SEAC 2006
SEAC Code of Practice as it involved consideration of unpublished research. SEAC noted that there was no evidence from the studies of a threshold dose of BSE at which the probability of infection becomes virtually negligible. Data suggested that reliable detection of PrPSc in the CNS was only possible in the few months prior to, and during, the clinical stage of infection. Low levels of PrPSc in PNS tissues could be detected at the same time, or after, PrPSc was detected in the CNS. The data from these studies will be submitted to EFSA for future discussions on BSE testing and controls.


SPONGIFORM ENCEPHALOPATHY ADVISORY COMMITTEE Minutes of the open session of the 92nd meeting held on 28th April 2006 Royal Horticultural Halls and Conference Centre Greycoat Street London SW1P 2QD Members: Professor C. Higgins (Chair) Mr. J. Bassett Professor D. Brown Professor N. Hooper Mr. P. Jinman (Deputy Chair) Professor C. Lasmézas Professor J. Manson Professor G. Medley Dr. P. Rudge Professor A. Williams Assessors: Dr. P. Christie (SE) Dr. A. Douglas (DARDNI) Dr. A. Gleadle (FSA) Mrs. E. Lawrence (DH) Dr. M. Simmons (NAW) Technical Experts: Dr. P. Barrowman (Defra) Dr. P. Bennett (DH) Mr. P. Burke (Defra) Professor N. Gill (HPA) Dr. I. Hill (FSA) Dr. D. Matthews (VLA) Dr. J. Stephenson (DH) SEAC Secretary: Miss K. Richards Secretariat: Dr. T. Barlow Dr. D. Cutts Dr. N. Ebenezer Dr. P. Keep
© SEAC 2006
Dr. C. Ravirajan
© SEAC 2006
ITEM 1 – CHAIR’S INTRODUCTION 1. The Chair welcomed everyone to the 92nd meeting of SEAC. 2. The Chair announced that Professor Alun Williams had joined SEAC to replace Professor McConnell who left the committee last year. Professor Williams is Head of Department of Veterinary Pathology and Infectious Diseases at the Royal Veterinary College and leads the European Union (EU) STOPPrions project. Mr Peter Jinman has been reappointed to SEAC following an open recruitment exercise and has also been reappointed Deputy Chair. 3. The SEAC Secretary explained that open meetings allow the public an opportunity to observe the committee at work and provide an insight into how an advisory committee provides independent scientific advice to Government. Government officials responsible for transmissible spongiform encephalopathy (TSE) policy are present and may be invited to contribute to discussions. 4. The committee will hold a reserved business session in the afternoon to allow discussion of unpublished scientific data relating to TSE infectivity in blood. This is in accordance with the SEAC Code of Practice. Short summaries of the open and reserved business discussions will be posted on the SEAC website next week. A list of website addresses of recently published reports relevant to TSEs has been tabled. 5. The next meeting will be held on Thursday 6th July 2006 at the Royal Horticultural Halls and Conference Centre in Westminster, London. 6. Apologies for absence have been received from Dr Jackie Chambers, Ms Diane McCrea, Professors James Nicoll and Margaret Stanley. 7. Members were reminded that they are obliged to declare any commercial or other interests they may have at the start of the relevant agenda items. They were also reminded of the obligation to notify the Secretariat of any changes to the register of members’ interests as soon as they occur. 3
© SEAC 2006
ITEM 2 – APPROVAL OF MINUTES FROM SEAC 91 (SEAC 92/1) AND MATTERS ARISING 8. The minutes were agreed as a correct record1. ITEM 3 - CURRENT ISSUES 9. SEAC was informed about the following issues: • Publication of a paper by Ironside et al.2 reporting the valine homozygous genotype of two of the three appendix samples found to be positive for the presence of abnormal prion protein (PrPSc) by Hilton et al. (2004)3. The third appendix could not be genotyped. The finding that both samples which could be genotyped were valine homozygous has implications for the predicted prevalence of vCJD infectivity in the UK population. SEAC had considered these data at SEAC 84. • Publication of a paper by Andreoletti et al.4 reporting that PrPSc was found in the spleen of an ARR homozygous sheep ten months after oral challenge with BSE. Dr Danny Matthews (Veterinary Laboratories Agency [VLA]) noted that the animals had been challenged with a very high dose of BSE at less than a week old in this study. • Following the agreement of the Chief Medical Officer, the Department of Health (DH) had requested that the Health Protection Agency (HPA) convene an expert group to consider the SEAC recommendation5 for testing of post mortem tissues to ascertain better the prevalence of vCJD infection in the UK. Professor Noel Gill (HPA) explained that the HPA is actively engaged in convening this group. SEAC would be asked to comment on the remit and membership of the group, probably by the end of May 2006. It was noted that DH has agreed to continue funding the tissue collection phase
1 Note added after SEAC 92. In paragraph 9, third bullet point “A paper on the case is being prepared by the Transfusion Medicine Epidemiology Review.” was changed to “A paper on the case is being prepared by the National Prion Clinic.” and in paragraph 25 “…sonicated microsomal fractions. Biochemical assays and hamster bioassay.” was changed to “…sonicated microsomal fractions by biochemical assays and hamster bioassay.” 2 Ironside et al. (2006) Variant Creutzfeldt-Jakob disease: prion protein genotype analysis of positive appendix tissue samples from a retrospective prevalence study. BMJ Online. 3 Hilton et al. Prevalence of lymphoreticular prion protein accumulation in UK tissue samples. J Pathol. 2004 203, 733-739. 4 Andreoletti et al. (2006) Bovine spongiform encephalopathy agent in spleen from an ARR/ARR orally exposed sheep. J. Gen. Virol. 87, 1043-1046. 5
© SEAC 2006
of the HPA National Anonymous Tonsil Archive that is collecting tonsils for vCJD infection prevalence estimation. • Defra and FSA tabled plans for studies to address recommendations made by the SEAC Sheep Subgroup for research on atypical scrapie6. It was noted that material for this research is in very short supply. Dr Peter Barrowman (Department of Environment, Food and Rural Affairs [Defra]) explained that Defra was looking to accumulate as much material as possible from the few atypical scrapie cases identified from TSE surveillance. Material would also be generated from challenge studies. Defra, the Food Standards Agency (FSA) and VLA are convening a group to consider priorities for use of the available material. A member suggested that whole heads could be collected at abattoir to increase the amount of available material. Dr Matthews explained that it was impracticable to collect whole heads. However, should sheep inoculated with atypical scrapie become diseased these animals would provide appreciable amounts of material for research. Inoculations of sheep with mouse atypical scrapie were under consideration as an additional method to generate more material but this approach may be inappropriate if phenotypic changes in strain occurred from passage in mice. • Unusual TSE test results obtained during routine surveillance from two French and one Cypriot sheep. Dr Matthews explained that the EU Expert Group on Strain Typing concluded that ring trial results of these samples were incompatible with the presence of experimental BSE in sheep. However, the unusual nature of the samples warranted further study so strain typing bioassays will be conducted. It is not yet possible to predict when results will be available. 6
© SEAC 2006
• Preliminary results from bioassays of one UK sheep TSE case identified in 2004 had given unusual results in biochemical tests. Dr Matthews explained that initial western blot of these samples was consistent with experimental BSE in sheep but that ring trial tests did not support this diagnosis. Strain typing bioassays had been conducted. One of the inocula had given an incubation period for clinical disease of 100 days in tg338 mice, which is inconsistent with BSE. Results of brain examinations were outstanding. • The SEAC Chair had attended a recent FSA stakeholder meeting in England and the SEAC Secretary attended equivalent meetings in Wales, Scotland and Northern Ireland to present and discuss the SEAC Sheep Subgroup statement. These workshops sought stakeholder views on options for possible additional precautionary measures in relation to atypical scrapie. The FSA Board would be returning to this issue in June 2006. The SEAC Chair had also attended the FSA Board meeting on 6th April 2006 when the Government’s contingency policy for BSE in sheep was discussed. • The study on transmission of BSE and vCJD in humanised mice7, considered in reserved business at SEAC 90, had been published. The minutes of the discussion have now been placed on the SEAC website. • Progress on recommendations made at SEAC 91 in relation to disposal of manure, crops and livestock at VLA Drayton. Mr Patrick Burke (Defra) explained that Defra would permit material from unchallenged animals and animals inoculated by the intracranial route to be composted and spread on arable land. Dr Matthews indicated that material from orally-challenged animals would continue to be composted and then used for coppice by VLA. It was likely that material from intracerebrally challenged animals would be treated in the same way. • The Creutzfeldt-Jakob Disease (CJD) Incidents Panel had been provided with the SEAC advice from SEAC 91 on the assessment of potential risks from medical implants containing bovine material. 7 Bishop et al. (2006) Predicting susceptibility and incubation time of human-to-human transmission of vCJD. Lancet Neurology. On line. 6
© SEAC 2006
• Sir William Stewart has agreed to chair a vCJD Patient Advisory Group being convened by DH to advise on the appropriate counselling and care for individuals defined as ‘at risk from vCJD for public health purposes’. Mrs Eileen Lawrence (DH) explained that the SEAC Chair and the Chair of CJD Incidents Panel had been invited to sit on this group. Requests for nominations to sit on this group had been submitted to relevant professional bodies and representatives from the National Prion Clinic and National CJD Surveillance Unit would be invited as special advisors. It was envisaged that the group would convene during the summer. ITEM 4 - AOB 10. There was no other business. ........


----- Original Message -----
From: "Terry S. Singeltary Sr."
Sent: Thursday, June 29, 2006 11:48 AM

##################### Bovine Spongiform Encephalopathy #####################

Date: June 29, 2006 at 9:12 am PST

Draft minutes of the open session of the 92nd meeting held on 28th April




1. At SEAC 85, SEAC reviewed the possible public and animal

health implications of chronic wasting disease (CWD) in UK deer

and produced a position statement. The committee concluded

that CWD currently poses relatively little risk to human health, or

to the health of cattle, sheep or goats in the UK. Nevertheless, as

a risk cannot be excluded a watching brief should be maintained.

In response to the recommendation that a watching brief be

maintained, the SEAC secretariat have produced a review of the

research on CWD published since 2004.


2. CWD is the only known transmissible spongiform encephalopathy

(TSE) to occur naturally in cervids. The disease is endemic in a

number of captive and free-ranging cervid species (mule deer,

white-tailed deer, Rocky Mountain elk and moose) in many areas

of North America. With the exception of deer imported into South

Korea, CWD has not been detected elsewhere in the world.

CWD is naturally transmissible from infected to susceptible

cervids and although the primary route(s) of infection remain

unclear it is possible that it may be transmitted via contaminated

environments. The origins of the disease are unknown.

3. CWD is experimentally transmissible to non-cervid species by

intracerebral inoculation. However, oral transmission of CWD

has only been successful to North American cervid species. It is

unclear whether CWD could be naturally transmitted to other

cervid and non-cervid species.

4. There have been no reported cases of transmission of CWD to

humans through the consumption of infected venison. There is

however limited epidemiological data on possible transmission of

CWD to humans through this route.

5. It is probable that captive and free-ranging deer species in the UK

were exposed to contaminated mammalian meat and bone meal


© SEAC 2006

prior to its ban in 1996. Studies investigating experimental

transmission of BSE to cervids are ongoing. Although no TSEs

have been detected in deer populations in the UK or elsewhere in

Europe, surveillance data are limited. As such it remains possible

that BSE may have been transmitted to UK deer which could

present a risk to consumers of venison.


6. At SEAC 85, SEAC considered the possible public and animal

health implications of CWD in UK deer based on a review of

published, and some unpublished, research on CWD, together

with surveillance data on TSEs in European cervids and

information on UK cervid populations. The committee also

considered the possibility that BSE may be present in UK deer. A

position statement summarising SEAC's consideration was



7. To address a recommendation made in the SEAC position

statement on CWD to keep a watching brief on emerging research

on CWD, a review of the published scientific literature from

October 2004 to May 2006 on CWD has been prepared by the

SEAC Secretariat (see Annex 1). The original literature review is

also provided at Annex 4 for ease of reference.

Summary of new research

8. In summary the new information shows that:

• to date, only one strain of CWD has been identified

conclusively however, limited research had shown the

possible presence of a further strain.

• the geographical distribution of CWD in cervids continues to

widen in North America. No cases of TSE infection have

been identified in surveys elsewhere in Europe or elsewhere

in the world with the exception of an imported case of CWD in

South Korea, although the surveys in deer have been limited.

• the host range broadened with confirmation of a first case of

CWD in free ranging moose in September 2005.

1 SEAC (2004) Chronic wasting disease in UK deer.


© SEAC 2006

• it is possible that TSEs may be transmitted via contaminated

soils lending support to existing evidence on the possibility of

environmental transmission of the CWD.

• the susceptibility to, and incubation period of, CWD in elk is

influenced by polymorphisms in codon 132 of the elk prion

protein gene.

• after more than 7 years following oral inoculation of cattle with

CWD-infected brain tissue, cattle show no clinical signs of


• cattle intracerebrally (ic) inoculated with CWD infected brain

tissue develop neuropathological patterns distinct from those

of BSE infection.

• PrPCWD can be detected in the skeletal muscles of CWD

infected cervids by bioassays using transgenic mice

expressing the cervid PrP.

• CWD has been transmitted to non-human primates but not to

humanised mice after ic inoculation of brain material from

CWD infected cervids.


9. A FSA funded study continues to investigate whether UK red deer

are susceptible to BSE infection by oral or ic challenge (Annex 2).

The study is set for completion in 2007. To determine the

preclinical status of deer a rectal biopsy method has been

employed with samples taken every 6 months from all remaining

animals in the study. To date, there are no clinical or pathological

signs of BSE in orally or ic challenged animals at 26 and 20

months respectively. Please note that Annex 2 has not been

circulated outside the committee as it contains new scientific data

that has not yet been published in a scientific journal.


snip...full text ;

Opinion of the European Food Safety Authority on a surveillance

programme for Chronic Wasting Disease in the European Union

Question N° EFSA-Q-2003-088

Adopted on 3rd June 2004

Annex to the EFSA Journal (2004) 70 On the opinion on a surveillance

programme for Chronic Wasting Disease in the EU

1 of 32


Report of the EFSA working group on a surveillance program for

Chronic Wasting Disease (CWD) in the EU


1 Preamble..........................................................................................................................1

2 Introduction.....................................................................................................................2

3 Diagnosis..........................................................................................................................4

4 Review Of The Different Screening Tests Used For The Diagnosis Of CWD............7

5 Surveillance of TSE in European cervid......................................................................10

6 Conclusions....................................................................................................................11

7 Recommendations..........................................................................................................13

8 Documentation provided to EFSA ...............................................................................14

9 Scientific Panel members ..............................................................................................14

10 Acknowledgement..........................................................................................................14

11 References......................................................................................................................15


Review of research published since November 2004

June 2006, SEAC Secretariat


15. Thirteen cattle calves were ic inoculated with a suspension of brain material

from CWD-infected mule deer with three calves kept as controls (Hamir et al,

2005). After six years, two of the inoculated animals showed clinical signs of

infection. PrPres was found in the CNS of five inoculated animals however,

the microscopic lesions expected in spongiform encephalopathy (SE) were

subtle in three cases and absent in two cases. The eight remaining

inoculated animals and three controls all tested negative for signs of infection.

The study suggests that CWD may be weakly transmissible to cattle after ic


16. In a follow-up study, six calves were inoculated ic with brain tissue derived

from the PrPCWD positive cattle described in paragraph 15 (Hamir et al,

2006a). At 16.5 months, all six inoculated cattle showed acute clinical signs

of disease resulting in the termination of the experiment. Although

microscopical SE-type lesions were not observed in any of the cattle, PrPres

was detected in CNS tissues. The authors noted that these findings were

similar to those in a study of cattle inoculated with the scrapie agent where, in

the absence of SE lesions, cattle showed clinical signs of infection and PrPres

was found in CNS tissues. The authors suggest that distinct differences exist

between CWD and BSE in cattle enabling clear identification of both diseases

if natural transmission of CWD to cattle were to occur.


It seems most

likely that CWD arose from a spontaneous change of endogenous

PrP resulting in a disease-associated and laterally-transmissible

form of PrP, although direct data to support this hypothesis

___are lacking___.

Host range

6. The known natural hosts for CWD are mule deer (Odocoileus

hemionus hemionus), black-tailed deer (Odocoileus hemionus

columbianus), white-tailed deer (Odocoileus virginianus), Rocky

Mountain elk (Cervus elaphus nelsoni) and moose (Alces alces).

The prevalence and geographical distribution of CWD in these

species appears to be increasing in North America in a manner

which is unlikely to be due simply to increased surveillance.


Human health implications

14. Epidemiological data on possible CWD infection of humans are

very limited. The possibility that clinical symptoms of CWD in

humans differ from those of Creutzfeldt-Jakob Disease (CJD)

cannot be excluded. There is no significant difference between the

prevalence of CJD in CWD endemic areas and other areas of the

world. However, because CJD surveillance in the USA is relatively

recent, not all CJD cases may have been identified. Additionally,

detection of a small increase in prevalence of such a rare disease

is very difficult. Investigation of six cases of prion disease in young

people (< 30 years of age) in the USA found no definite causal link

with consumption of venison from known CWD endemic areas.

The disease characteristics in these cases were indistinguishable

from sporadic CJD or Gerstmann-Sträussler-Scheinker syndrome.

Likewise, in a study of three hunters (> 54 years of age) diagnosed

with sporadic CJD, no link with consumption of venison from CWD

endemic areas was found. No causal link was found in an

investigation of three men with neurological illnesses who were

known to partake in “wild game feasts”. Only one of these subjects

was found to have a prion disease and this was also

indistinguishable from sporadic CJD.



Written by Dr Debra Bourne, Wildlife Information Network, October 2004, for SEAC


Potential risk to domestic cattle & sheep

211. To date, no transmission of CWD has been reported in domestic species living in

CWD endemic areas or in research facilities with CWD. Monitoring is ongoing (Gould et al.,

2003; Williams & Miller 2002; Belay et al., 2004). It has been possible to infect domestic

cattle, goats and sheep by intracerebral inoculation, although not in all inoculated individuals

(Hamir et al., 2003a; Hamir et al., 2004a); see paragraphs 66-67. Data from intracerebral

inoculation experiments show that diagnostic methods currently in use for BSE surveillance

would detect the CWD agent in cattle and sheep if it were present (Hamir et al., 2003a).

212. Data from in vitro experiments suggests that there may be a considerable “species

barrier” limiting transmission of CWD from cervids to domestic cattle and, to a lesser extent,

to domestic sheep. In a cell-free conversion system, PrPCWD from elk, mule deer or whitetailed

deer showed 5-to-12-fold lower conversion efficiency of bovine PrP-sen than for intercervid

conversion reactions; conversion efficiency of ovine PrP-sen (ovine PrP-AQ) was also

less than half as efficient as for homologous cervid reactions (Raymond et al., 2000).

213. There is a theoretical risk than CWD could be transmitted to cattle via incorporation of

infected tissue from Cervidae into meat and bone meal. The risk for this occurring in the USA

was considered [in 1992] to be small “because CWD is believed to be rare and localized, and

the proportion of harvested Cervidae whose offal is rendered is probably small” [in the USA]

(Saunders, 1994). The feeding of ruminant-derived protein to ruminants has been banned in

Canada and the USA since 1997 (Kahn et al., 2004). The US Food and Drug Administration

(FDA) has, since November 2002, banned the use of “material from Chronic Wasting Disease

(CWD)-positive animals, or animals at high risk for CWD, to be used as an ingredient in feed

for any animal species.” Animals considered to be at high risk for CWD were stated to

include animals from CWD-positive captive herds, free-ranging animals from the CWDendemic

area in Colorado and Wyoming, deer from the CWD eradication zone in Wisconsin

and also “deer from any areas designated around any new foci of CWD infection that might

be identified through surveillance or hunter harvest testing” (FDA, 2002). Such policies

should minimise the potential oral exposure of domestic ruminants to CWD-agent in feed.

Potential risk to other species

214. Since BSE appears to have been transmitted orally to various Felidae (Kirkwood et

al., 1995; Bourne, 2004b), the possibility of CWD being transmitted to carnivores must be


215. Experimentally, CWD has been successfully transmitted by intracerebral inoculation

to domestic ferrets (Mustela putorius fero) and to American mink (Mustela vison), but not to

common raccoons (Procyon lotor) (Williams, Young & Marsh 1982; Williams & Young,

1992; Williams et al., 1992; Hamir et al., 2003c; Sigurdson et al., 2003). Since raccoons are

highly adaptable carnivores which may include carrion in their diet (Hamir et al., 2003c), the

lack of success in transmission of CWD to raccoons even by intracerebral inoculation is


216. There is no published data on transmission or attempted transmission of CWD to

felids or canids.


217. To date there are no known cases of human prion disease attributable to CWD

transmitted to humans (Belay et al., 2004). While limited epidemiological investigations to

date have not shown any links between CWD and humans with spongiform encephalopathies

CWD Review / Dr Debra Bourne / October 2004 / For SEAC / Page 45 of 66

this data must be considered along with a caveat: “because CWD is a relatively new TSE, it is

unlikely that enough people have consumed enough CWD-affected cervids to result in a

clinically or pathologically recognizable disease attributable to CWD, especially considering

the very long incubation periods characteristic of TSE diseases.” (Race et al., 2002)

Epidemiological investigations

218. Epidemiological investigations have failed to show any links between cases of prion

disease in unusually young people or in hunters in the USA and CWD (CDC, 2003). Two

major epidemiological investigations have been carried out, one on cases of CJD in unusually

young individuals in the USA, the second on a group of men from Wisconsin who developed

neurological diseases.

219. The first study (Belay et al., 2001) focused on three individuals, two 28 years of age

and the third 30 years old, diagnosed with CJD in the USA between 1st January 1997 and 31st

May 2000, and without any established risk factors for CJD (family history, receipt of human

growth hormone, receipt of grafts of dura mater or cornea, or previous neurological surgery)

and concluded that there was no strong evidence for a causal link with CWD. None of the

individuals had travelled to Europe (therefore a link with BSE was unlikely). Two of the

individuals were hunters who regularly consumed game meat while the third (case 1) had, as a

young child, regularly consumed venison from animals hunted by family members and on two

occasions from a family friend. Two of the individuals (cases 1 and 2) had undergone tonsillar

surgery as children; the third had never received any surgical treatment. One individual (case

1) had eaten venison mainly hunted in Maine, occasionally hunted in New Jersey, and, on two

occasions at about six years old, elk meat which had probably been harvested in Wyoming.

The second person (case 2) had hunted cervids mainly in Utah, but had harvested an elk in

southwestern Wyoming on one occasion (less than three years before onset of clinical signs)

and had hunted in British Columbia on one occasion nine years before onset of illness. The

third person (case 3) had hunted close to home and never in Colorado or Wyoming although

the plant where he took his carcasses for processing did also process some elk from Colorado

each year. The clinical signs, duration of illness and histopathological findings for the three

individuals showed no obvious similarities to one another. One individual was

methionine/methionine homozygous at codon 129 of the PRNP (case 1), one was

homozygous for valine at this gene (case 2) and the third (case 3) was heterozygous

methionine/valine. Immunohistochemistry revealed strong staining with a “synaptic” pattern

in the first individual and weak staining with a “synaptic” pattern in the second case; in case

3, based on a brain biopsy sample obtained at an early point in the illness, staining was

questionable and possibly showed a synaptic pattern. Cases 2 and 3 showed a “Type 1”

immunoblot pattern, this test had not been carried out for case 1. It was noted that none of

these three individuals had a definite history of consumption of venison from the geographical

areas in which CWD was known to be endemic in Colorado and Wyoming, and no CWD had

been identified in 299 deer and sampled from the area in which most of the venison consumed

by patient 1 had originated, nor in 404 deer and 196 elk sampled from the area in which most

of the venison consumed by patient 2 had originated, nor in 138 deer samples from the area in

which most of the venison consumed by patient 1 had originated. Additionally, there was no

homogeneity in phenotypic expression of the disease and all three possible options for coding

at codon 129 of the PRNP gene were represented. Since a survey had indicated that

approximately 40% of blood donors in the USA consumed venison from wild cervids, it was

considered most likely that coincidence explained why three of the four young (30 years old

or younger) individuals with sporadic CJD reported in the USA after March 1996 had

consumed such meat (Belay et al., 2001).

CWD Review / Dr Debra Bourne / October 2004 / For SEAC / Page 46 of 66

220. The second major epidemiological investigation centred around three men from

Wisconsin and Minnesota who had died from degenerative neurological illnesses and who

had participated in “wild game feasts” in northern Wisconsin. Full investigation including

examination of fixed brain tissue confirmed CJD in only one of the three individuals. Wild

game eaten during the feasts was harvested mainly in Wisconsin but also in areas of

Colorado, Wyoming and Montana; CWD was not known to be endemic in the areas where the

game was hunted at the time that the game was harvested. Further investigations of other

possible attendees of the feasts revealed 34 participants, all male, of whom a total of seven

were deceased, including the three individuals in the initial investigation. Causes of death in

the other four deceased individuals were not attributed to nor associated with any

degenerative neurological disorder and no signs or symptoms associated with a degenerative

neurological disorder were noted for any of the remaining living participants of the feasts. It

was noted that only one case of CJD had occurred among known participants at the feasts,

that this case was consistent with the commonest form of sporadic CJD, that this individual

had only participated in one feast and that it was unlikely that he had consumed CWDinfected

venison at the feasts “because venison and other game from outside Wisconsin that

was served at these feasts did not originate from known CWD-endemic areas.” Limitations of

the investigations were noted to include reliance on recall of events from up to 25 years

previously and the fact that not all participants in the feasts could be contacted and

interviewed. However, those who were interviewed agreed in their recall of events (CDC,


221. It is important to recognise that the limited epidemiological investigations that have

been carried out are not able to rule out the possibility that CWD might play a role in causing

illness in humans (CDC, 2003).

222. Three further cases of prion disease in young humans in the USA have been

investigated for possible links to CWD (Belay et al., 2004). The first case was a 25-year-old

man who died in 2001 after about 22 months of illness. Gerstmann-Sträussler-Scheinker

syndrome (GSS) was diagnosed by analysis of the prion gene, with a P102L mutation

together with valine at codon 129 in the mutant allele. It was noted that the disease had

occurred at an unusually young age, even for GSS, and the possibility that exposure to CWDinfected

venison contributed to early onset of the disease could not be ruled out; the patient’s

grandfather had regularly hunted in southeastern Wyoming, around the known CWD-endemic

area, and had given venison to the patient’s family. Two other cases of prion disease occurred

in individuals of 26 and 28 years of age, from adjacent counties, and with onset of illness only

months apart, therefore an environmental source of infection was investigated. However,

these two individuals were finally diagnosed with different prion diseases: sporadic CJD in

one case and GSS in the other, indicating that a common cause was unlikely. In the first case

CJD was confirmed from autopsy samples (by histopathology, immunohistochemistry and

immunoblotting); the individual had no history of hunting nor of regular consumption of

venison, and although he may have eaten venison originating from the Upper Peninsula of

Michigan while at college CWD has never been detected in deer from Michigan.

Phenotypically this individual fit the “MM2 sporadic CJD” phenotype described by Parchi et

al. (1999). In the other case post mortem immunohistochemistry revealed prion deposition

which was consistent with GSS and a GSS P102L mutation was detected in a blood sample

from one parent (appropriate samples were not available from the affected patient); this

individual may possibly have eaten venison from Michigan on one occasion at about two

years of age (Belay et al., 2004).

223. A further three cases of CJD in individuals of 54 to 66 years old who were deer and

elk hunters (two individuals) or ate wild-harvested venison (one individual) have been

CWD Review / Dr Debra Bourne / October 2004 / For SEAC / Page 47 of 66

investigated. There was no evidence that any of these individuals had hunted in known CWDendemic

areas; information available indicated hunting or eating venison from Washington

State and Pennsylvania. Two individuals were V/V at codon 129 the third was M/M; they

were considered to fit known subtypes of sporadic CJD (MM1, VV1 and VV2 subtypes as

described by Parchi et al. (1999)). Further investigations were also made on the only two

nonfamilial cases of CJD in individuals with a history of eating venison from the known

CWD-endemic areas. One was reported to have eaten venison from two deer harvested in an

area with endemic CWD, but both deer had been tested and not found to be CWD-positive;

the patient’s illness was consistent with the CJD subtype MM1. The other individual grew up

in a CWD-endemic area and ate locally-harvested venison; her disease fit the MM1 CJD

phenotype and no atypical neurological features were noted (Belay et al., 2004).

224. Additional epidemiological notes are that the incidence and age distribution of CJD in

Colorado and Wyoming, where CWD is thought to have been endemic for decades, are

similar to those found in other areas of the USA. In Wyoming, seven cases of CJD have been

reported between 1979 and 2000 with an average annual age-adjusted CJD death rate of 0.8

per million and no cases reported in humans less than 55 years old. In Colorado in the same

period 67 cases of CJD have been reported, with an average annual age-adjusted CJD death

rate of 1.2 per million (Belay et al., 2004).

225. In summary, there is no evidence of an increase in incidence of CJD in Colorado and

Wyoming, nor have epidemiological investigations carried out so far found any evidence of a

link between CWD and cases of CJD in persons in the USA (Belay et al., 2001; CDC, 2003;

Belay et al., 2004).

Laboratory studies

226. There is evidence from an in vitro cell-free system that there may be a considerable

“species barrier” reducing the probability that CWD will affect humans. It was shown that

PrPres associated with chronic wasting disease (PrPCWD) from elk, mule deer or white-tailed

deer was able to readily induce substantial conversion of recombinant cervid PrPsen

molecules form any of these three species to the protease-resistant state. In the same system,

CWD-associated PrPres was shown to convert human PrPsen but at a much lower efficiency:

more than 14-fold lower efficiency than inter-cervid conversion reactions and more than fivefold

lower than conversion of human PrPsen by PrPres from the brains of humans with CJD

(Raymond et al., 2000). While encouraging, interpretation of this study is complicated by the

fact that conversion of human PrPC by PrPBSE and PrPSc from sheep were of similar efficacy,

both being more than 10-fold less efficient compared with corresponding homologous

conversions) and one of these appears to be orally transmissible to humans (BSE) while the

other (scrapie) appears not to be (Raymond et al., 2000). In previous experiments PrPBSE had

showed 10-fold greater conversion efficacy for bovine PrPsen than for human codon 129-M

(methionine) PrPsen and 30-fold greater conversion efficacy than for human codon 129-V

(valine) PrPsen, while ovine PrPSc showed five-fold greater conversion efficacy for ovine

PrPsen than for human 129-M PrPsen and eight-fold greater conversion than for human 129-

V PrPsen (Raymond et al., 1997).

227. Results of recent work in transgenic mice expressing human PrP (see paragraph 71), in

which transmission of CWD from elk by intracerebral inoculation failed, was considered to

“strongly suggest” a species barrier to transmission of elk CWD to humans (Kong et al.,


CWD Review / Dr Debra Bourne / October 2004 / For SEAC / Page 48 of 66

Potential risk from consuming cervid products

Velvet antler

228. Limited studies to date indicate risk from this product may be very low. No CWDspecific

PrP accumulation was detected in a sample of velvet from an elk stag which

developed clinical CWD about three months later; there were severe brain lesions and

extensive CWD-specific PrP staining in both the brain and peripheral lymphoid tissue of the

stag (Kahn et al., 2004).

Consumption of venison and other parts of the animal

229. PrPCWD has not been detected in muscle tissue from infected cervids (Spraker et al.,

2002c). However, it has been recommended by the World Health Organisation that no parts or

products of any animal know to be CWD-positive should be consumed (WHO, 2000). Public

health authorities in the USA and Canada have indicated agreement with this (Canadian Food

Inspection Agency, 2003; Chronic Wasting Disease Alliance, 2004). It has been suggested

that if a harvested cervid is being tested for CWD, the test results should be awaited before

the meat is eaten (Wisconsin Department of Agriculture, Trade and Consumer Protection,

2002). Authorities in North America have widely advised that (a) tissues likely to contain the

greatest amount of CWD agent in infected cervids, including the brain, spinal cord, lymph

nodes, spleen, tonsils and eyes, should not be consumed from any harvested deer; (b) meat

should be boned out and fat and connective tissue removed (which would also remove lymph

nodes); and (c) hunters should avoid eating meat from deer or elk which look sick or which

test positive for CWD (Buege, 2002; Chronic Wasting Disease Alliance, 2004; Williams et

al., 2002; Wisconsin Department of Agriculture, Trade and Consumer Protection, 2002;

Belay et al., 2004).

Potential risk from handling and processing cervids

230. In order to minimise any potential risk from exposure to the agent of CWD, hunters,

meat processors and taxidermists handling cervid carcasses are advised to wear latex or

rubber gloves when handling or dressing cervids from CWD-endemic areas, to minimise

handling of brain and spinal cord, and to thoroughly wash knives and other implements after

use on deer or elk carcasses (Belay, 2004; Williams et al., 2002). It has been suggested that

the risk of “build-up” of infectious CWD agent in a venison processing plant would be

unlikely (Buege, 2002).

Potential risk from disposal of carcasses and subsequent contamination of


231. In 2002, a risk analysis was produced on disposal of deer from Wisconsin in

municipal solid landfills. It was noted that it is not known how much infected material a

human (or animal) must consume or be exposed to in order to be infected with CWD. The

report took into account the probable species barrier for transmission to humans (Raymond et

al., 2000). It was noted that the CWD agent is hydrophobic and likely to adhere to organic

materials within a landfill, taking several months to move through the landfill, and that any

infectivity exiting the landfill would be captured in the landfill effluent. If effluent was

transferred to a wastewater plant (rather than recirculated in the landfill) the agent would be

expected to partition with the sludge fraction, which would be diluted greatly with other

solids and mixed with nine inches (22.5 cm) of topsoil, providing “an extremely large dilution

factor.” It was concluded that there was no significant risk to human health from disposing of

deer infected with CWD in properly constructed landfill sites (Olander, 2002).

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Version 1.0 Animal Feed Use & Supply Routes 07/06//2006

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© Defra 2006





M03024: Susceptibility of red deer (Cervus elaphus elaphus) to BSE
Thursday 09 October 2003

This research project aims to determine whether BSE can be transmitted to UK red deer by including infected material in their feed.

Study Duration: April 2003 to April 2010

Contractor: Veterinary Laboratories Agency

The major cause of the spread of the BSE epidemic was attributed to the feeding of contaminated meat and bonemeal (MBM) in the protein rations fed to cattle. The use of MBM in animal feed was not restricted to cattle rations and it is known that MBM was included in the concentrates fed to farmed deer. BSE has been shown to be naturally or experimentally transmissible to a wide range of different ungulate species and deer are known to be susceptible to an endemic TSE (chronic wasting disease, CWD) which is prevalent in North America. However, to date, no TSE infections of UK deer have been reported.
Should BSE infection have been transmitted into the UK red deer population, the CWD precedent would suggest that there is potential for both spread and maintenance of the disease in both free living and captive UK deer populations. The purpose of this study is to investigate the susceptibility of UK red deer to BSE infection and to determine the clinical and pathological phenotype.

Research Approach
The initial objective of the study is to determine whether orally infected UK red deer are susceptible to bovine BSE agent. Groups of orally dosed deer will be sacrificed at 6, 12 and 60 months post inoculation and necropsies carried out. A range of tissue samples will be retained for further analysis such as immunohistochemistry. All animals will also be monitored clinically throughout the experiment to define any clinical phenotype.

-------- Original Message --------
Subject: Susceptibility of red deer (Cervus elaphus elaphus) to BSE
Date: Mon, 8 Mar 2004 20:29:54 -0600
From: "Terry S. Singeltary Sr."
Reply-To: Bovine Spongiform Encephalopathy

TSE Project Details
Project Ref M03024
Theme Risk assessment of SEs
Sub Theme An evaluation of SEs transmission modalities from cattle to
man and other food animals, environment vectors
MRC Priority
Title Susceptibility of red deer (Cervus elaphus elaphus) to BSE
Principle Investigator Dr Hawkins PI Department Veterinary Laboratories
PI Location Weybridge PI Organisation Veterinary Laboratories Agency

Last Year Cost £ This Year Cost £
Start Date 01/04/2003 End Date 01/04/2010
Status Current Total Cost £ 1,485,458
Abstract The major cause of the spread of BSE was attributed to the
feeding of contaminated meat and bone meal (MBM) in the protein rations
fed to cattle. The use of MBM in animal feed was not restricted to
cattle rations and it is known that MBM was included in the concentrates
fed to farmed deer. BSE has been shown to be naturally or experimentally
transmissible to a wide range of different ungulate species and deer are
known to be susceptible to an endemic TSE (chronic wasting disease, CWD)
which is prevalent in North America. However, to date, no TSE infections
of UK deer have been reported. The initial objective of the study is to
determine whether orally infected UK red deer are susceptible to bovine
BSE agent. Groups of orally dosed deer will be sacrificed at 6, 12 and
60 months post inoculation and necropsies carried out. A range of tissue
samples will be retained for further analysis such as
immunohistochemistry. All animals will also be monitored clinically
throughout the experiment to define any clinical phenotype.

©2004 Medical Research Council

Susceptibility of Red Deer to BSE
Dagleish, M
FSA funded project in collaboration with VLA
No known cases of BSE have ever been reported in any species of deer. However, an EU directive has decreed that provision must be made for all ruminant species entering the human food chain to be screened for BSE and free living and captive deer may have been exposed to the BSE agent. BSE has affected a range of different hoof stock (domestic and exotic cattle, eland, nyala, greater kudu, gemsbok and Arabian and scimitar-horned oryx) and several species of cats (cheetah, puma, tiger, lion and domestic cats) by presumed ingestion of contaminated meat and bone meal in food. As both captive and free ranging UK deer enter the human food chain it is important to determine their susceptibility to transmission of the BSE agent, the nature of any possible resultant clinical disease and to develop methods of screening deer tissues for the BSE agent to maintain the high standards of food safety within the UK .

This study will determine in the first instance whether the BSE agent can actually be transmitted to red deer. If this is possible the study will also provide a description of any resultant clinical disease, pathological changes and positive control tissue material all of which would aid surveillance for BSE in deer within the UK .

Moredun Research Institute
Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZ, Scotland
Telephone - 0131 445 5111, International +44 131 445 5111,

Site last updated: 22 Jun 2006


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