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From: TSS ()
Subject: SEAC 90th meeting held on the 24th Nov $ THE vCJD EPIDEMIC
Date: December 2, 2005 at 8:51 am PST

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

TSS
SEAC 90th meeting held on the 24th Nov $ THE vCJD EPIDEMIC
Thu Dec 1, 2005 10:23
70.110.89.187


1

© SEAC 2005

NINETIETH MEETING OF THE SPONGIFORM

ENCEPHALOPATHY ADVISORY COMMITTEE

The Spongiform Encephalopathy Advisory Committee held its 90th

meeting in Edinburgh on 24th November 2005, and discussed the

following matters:

CURRENT ISSUES

SEAC was informed about the following issues:

• The SEAC Sheep Subgroup will meet on 24th January 2006

to consider emerging scientific developments on atypical

scrapie and possible implications for the National Scrapie

Plan (NSP) and EU TSE roadmap.

• A recent article1 reporting detection of relatively low levels of

abnormal prion in the mammary glands of five Italian farmed

sheep with coincident clinical signs of natural scrapie and

mastitis. Abnormal prion protein was absent in the

mammary gland of sheep free of mastitis or scrapie. SEAC

agreed that the study provided further evidence that

inflammatory diseases can alter the distribution of abnormal

prion protein in infected animals. However, the particular

form of mastitis was rare in the UK and the sheep breed

studied is prone to particular diseases. SEAC considered

the study to be important. However, it would be premature to

come to firm conclusions about the possible implications of

the findings for UK flocks and further investigations should

be undertaken. It was noted that regulations restrict milk

from animals with clinical mastitis from entering the food

chain.

1 Ligios et al. (2005) PrPSc in mammary glands of sheep affected by scrapie

and mastitis. Nature Medicine, 11 published online 04/11/05.

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© SEAC 2005

• The European Food Safety Authority recently published

scientific opinions on the evaluation of rapid post mortem

TSE tests for small ruminants and on classification of

atypical TSE cases in small ruminants.

• The European Commission recently published a report of the

Food and Veterinary Office recent inspection of BSE control

and surveillance measures in Great Britain in June 2005.

• Defra had issued consultations (i) to seek views on the

application of a breeding programme to reduce scrapie

susceptibility in rare sheep breeds and (ii) on possible

amendments to legislation to lift the EU ban on export of

cattle and cattle products from the UK and on the

harmonisation of UK and EU specified risk material controls.

• The Chairs of committees concerned with CJD met recently

with officials from the Department of Health (DH) and Health

Protection Agency (HPA) to discuss issues of mutual interest

and to ensure a joined up approach was taken by the

committees.

• Mr Peter Jinman (Deputy Chair of SEAC) participated in a

Food Standards Agency (FSA) workshop to allow the FSA’s

new Chair, Dame Deirdre Hutton, to learn more about the

committees that provide advice to the FSA.

• The Chair participated in a joint FSA/Royal Society workshop

to discuss the possible input of social sciences into the risk

assessments conducted by independent advisory

committees.

• The SEAC Secretariat has begun an exercise to recruit two

new specialist members to SEAC: one member with

veterinary clinical expertise and one member with veterinary

molecular and biochemical expertise.

vCJD UPDATE

SEAC was updated on the latest figures on sCJD and vCJD cases

from the National CJD Surveillance Unit. Between May 1990 and

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© SEAC 2005

August 2005, 788 cases of sCJD had been identified with a mean

age at death of 66 (range 20-95) years. The genotype distribution

of these cases was 65% MM, 17% MV and 18% VV at codon 129

of the prion protein gene. Up to October 2005, 158 vCJD cases

have been reported in the UK with mean age of death of 30 (range

14-74) years. There has been no significant shift in the mean age

of death of vCJD cases since the start of the epidemic; the reason

for this is uncertain. All of the 134 UK vCJD cases tested to date

are of the MM genotype. Elsewhere in the world, 27 vCJD cases

have been reported: 15 in France, 3 in the Republic of Ireland, 2 in

the USA and single cases in Italy, Canada, Saudi Arabia, Japan,

Netherlands, Spain and Portugal. For one Irish case, the

Japanese, Canadian and both USA cases, infection was likely to

have occurred in the UK.

Statistical analysis of the UK incidence of vCJD deaths indicates

the epidemic reached a peak at about 6 deaths per quarter in mid-

2000 and has been in decline since then. However, a small

increase in the number of onsets of vCJD had been noted in 2004

but it was unclear whether this increase was meaningful. These

cases appear similar to previous cases in terms of genotype and

clinical symptoms.

The committee was informed about investigations into the

biochemical signature of the prion protein in samples from sCJD

and vCJD cases. These analyses suggest that more than one

form of abnormal prion protein might be present in the same

sample. These findings suggest that the relationship between

abnormal prion protein form and TSE strain is more complex than

previously thought.

SEAC EPIDEMIOLOGY SUBGROUP STATEMENT

SEAC welcomed and endorsed a position statement produced by

the SEAC Epidemiology Subgroup in response to the committee’s

request for a consideration of the nature and future profile of the

vCJD epidemic. The committee agreed that better ascertainment

of the prevalence of infection was vital. Further consideration on

how this might be best progressed was very important, and would

be followed up with some urgency.

BARB CASE CLUSTERS

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© SEAC 2005

SEAC was informed that up to 20 November 2005, 114 BSE cases

born after the reinforced feed ban in August 1996 (BARB cases)

had been identified in GB. Analysis suggests there is a decline in

the risk of BSE infection for successive birth cohorts such that the

BARB epidemic is unlikely to be sustained by animals born after

31 July 2000. Clusters of BARB cases within herds had been

identified (4 pairs, 2 triplets and 1 quadruplet). Farm investigations

of these clusters suggested that the feed the animals may have

received when young could have been contaminated by old

residual feed in storage bins. SEAC noted that advice to farmers

is being formulated to remove this potential risk factor.

EVOLUTION OF THE PRION PROTEIN GENE

SEAC considered a recent report2 on a theoretical investigation of

the molecular evolution of the prion protein gene (PRNP) in

ruminants. This suggested that evolutionary selection pressures

may act to maintain variation in the sheep gene, in contrast to the

NSP, which is reducing variation in PRNP to select genotypes

more resistant to scrapie.

SEAC considered that, although the methodology used was

sound, the conclusions were not as robust as claimed. This would

be followed up by the SEAC Sheep Subgroup. It was noted that

Defra had commissioned a semen bank to preserve existing prion

protein gene variation as well as a project to examine the potential

relationship between PRNP genotype and fitness and production

traits.

HORIZON SCANNING

The committee was informed by representatives from DH, FSA

and Defra about issues that might require future consideration by

SEAC, including:

• estimation of the size of the vCJD epidemic, minimisation of

the risks of secondary transmission of vCJD (DH).

• development of in life diagnostic tests for TSEs (DH, Defra

and FSA).

2 Slate (2005) Molecular evolution of the sheep prion protein gene. Proc. R.

Soc. B. 272, 2337-2344.

5

© SEAC 2005

• relaxation of TSE control measures and the scope of TSE

surveillance (Defra and FSA).

PUBLIC QUESTION AND ANSWER SESSION

The Committee answered questions from the public relating to the

work of SEAC. These included questions about the implications of

the apparent decline in the number of suspected cases of CJD

reported in the UK in recent years, the potential of magnetic

resonance imaging to detect CJD before the onset of clinical

symptoms and the progress of the FatePride environmental study

on TSEs.

vCJD INFECTIVITY IN BLOOD

The National Blood Service asked SEAC to review, in light of new

information, the key underpinning assumptions made in an

assessment of transmission risks via blood transfusion that SEAC

had accepted in 2002. The item was discussed in the reserved

business session as it involved consideration of unpublished

research.

SEAC noted that new data supported assumptions made about the

potential for blood from infected but asymptomatic individuals to be

infectious and the susceptibility of non-MM PRNP codon 129

genotypes to infection. However, there were very few new data to

inform estimates of infectivity levels in blood, the possible change

in infectivity levels in blood over the course of the incubation period

and the distribution of infectivity in blood components. The

committee noted that robust research in these areas was lacking.

TSE STUDIES IN MOUSE MODELS

SEAC considered findings from studies using transgenic mice on

human to human vCJD transmission, and also the relationship

between infectivity levels and concentrations of abnormal prion

protein in the brain of animals with TSEs. These issues were

discussed in a reserved business session to allow consideration of

unpublished research.

SEAC agreed that the characteristics of transgenic models of TSE

infections must be carefully considered when assessing the

6

© SEAC 2005

implications of research using such models. The committee noted

that the new research suggests there is no clear correlation

between abnormal prion protein concentrations and the titre of

TSE infectivity in some animal models. Thus, abnormal prion

protein may not always be a good surrogate marker for infectivity.

The implication of this finding for rapid diagnostic TSE tests should

be considered. The committee considered that the precise role of

abnormal prion protein in relation to the infectious and

neurodegenerative properties of TSE agents remains unclear.

http://www.seac.gov.uk/summaries/seac89_summary.pdf

SEAC EPIDEMIOLOGY SUBGROUP POSITION STATEMENT ON

THE vCJD EPIDEMIC

http://www.seac.gov.uk/papers/90-8.pdf

REGISTER OF MEMBERS’ INTERESTS

(November 2005)

http://www.seac.gov.uk/committee/interest.pdf


http://neurology.thelancet.com Published online October 31, 2005


Coexistence of multiple PrPSc types in individuals with

Creutzfeldt-Jakob disease

Magdalini Polymenidou, Katharina Stoeck, Markus Glatzel, Martin Vey, Anne Bellon, and Adriano Aguzzi

Summary

Background The molecular typing of sporadic Creutzfeldt-Jakob disease (CJD) is based on the size and glycoform

ratio of protease-resistant prion protein (PrPSc), and on PRNP haplotype. On digestion with proteinase K, type 1 and

type 2 PrPSc display unglycosylated core fragments of 21 kDa and 19 kDa, resulting from cleavage around amino

acids 82 and 97, respectively.

Methods We generated anti-PrP monoclonal antibodies to epitopes immediately preceding the differential proteinase

K cleavage sites. These antibodies, which were designated POM2 and POM12, recognise type 1, but not type 2, PrPSc.

Findings We studied 114 brain samples from 70 patients with sporadic CJD and three patients with variant CJD.

Every patient classified as CJD type 2, and all variant CJD patients, showed POM2/POM12 reactivity in the

cerebellum and other PrPSc-rich brain areas, with a typical PrPSc type 1 migration pattern.

Interpretation The regular coexistence of multiple PrPSc types in patients with CJD casts doubts on the validity of

electrophoretic PrPSc mobilities as surrogates for prion strains, and questions the rational basis of current CJD

classifications.


snip...


The above results set the existing CJD classifications

into debate and introduce interesting questions about

human CJD types. For example, do human prion types

exist in a dynamic equilibrium in the brains of affected

individuals? Do they coexist in most or even all CJD

cases? Is the biochemically identified PrPSc type simply

the dominant type, and not the only PrPSc species?


http://neurology.thelancet.com Published online October 31, 2005


Animal Prion Diseases Relevant to Humans (unknown types?)
Thu Oct 27, 2005 12:05
71.248.128.109

About Human Prion Diseases /
Animal Prion Diseases Relevant to Humans

Bovine Spongiform Encephalopathy (BSE) is a prion disease of cattle. Since 1986, when BSE was recognized, over 180,000 cattle in the UK have developed the disease, and approximately one to three million are likely to have been infected with the BSE agent, most of which were slaughtered for human consumption before developing signs of the disease. The origin of the first case of BSE is unknown, but the epidemic was caused by the recycling of processed waste parts of cattle, some of which were infected with the BSE agent and given to other cattle in feed. Control measures have resulted in the consistent decline of the epidemic in the UK since 1992. Infected cattle and feed exported from the UK have resulted in smaller epidemics in other European countries, where control measures were applied later.

Compelling evidence indicates that BSE can be transmitted to humans through the consumption of prion contaminated meat. BSE-infected individuals eventually develop vCJD with an incubation time believed to be on average 10 years. As of November 2004, three cases of BSE have been reported in North America. One had been imported to Canada from the UK, one was grown in Canada, and one discovered in the USA but of Canadian origin. There has been only one case of vCJD reported in the USA, but the patient most likely acquired the disease in the United Kingdom. If current control measures intended to protect public and animal health are well enforced, the cattle epidemic should be largely under control and any remaining risk to humans through beef consumption should be very small. (For more details see Smith et al. British Medical Bulletin, 66: 185. 2003.)

Chronic Wasting Disease (CWD) is a prion disease of elk and deer, both free range and in captivity. CWD is endemic in areas of Colorado, Wyoming, and Nebraska, but new foci of this disease have been detected in Nebraska, South Dakota, New Mexico, Wisconsin, Mississippi Kansas, Oklahoma, Minnesota, Montana, and Canada. Since there are an estimated 22 million elk and deer in the USA and a large number of hunters who consume elk and deer meat, there is the possibility that CWD can be transmitted from elk and deer to humans. As of November 2004, the NPDPSC has examined 26 hunters with a suspected prion disease. However, all of them appeared to have either typical sporadic or familial forms of the disease. The NPDPSC coordinates with the Centers for Disease Control and state health departments to monitor cases from CWD-endemic areas. Furthermore, it is doing experimental research on CWD transmissibility using animal models. (For details see Sigurdson et al. British Medical Bulletin. 66: 199. 2003 and Belay et al. Emerging Infectious Diseases. 10(6): 977. 2004.)


http://www.cjdsurveillance.com/abouthpd-animal.html


SEE STEADY INCREASE IN SPORADIC CJD IN THE USA FROM 1997 TO 2004. SPORADIC CJD CASES TRIPLED, and that is with a human TSE surveillance system that is terrible flawed. in 1997 cases of the _reported_ cases of cjd were at 54, to 163 _reported_ cases in 2004. see stats here;

p.s. please note the 47 PENDING CASES to Sept. 2005

p.s. please note the 2005 Prion D. total 120(8) 8=includes 51 type pending, 1 TYPE UNKNOWN ???

p.s. please note sporadic CJD 2002(1) 1=3 TYPE UNKNOWN???

p.s. please note 2004 prion disease (6) 6=7 TYPE UNKNOWN???


http://www.cjdsurveillance.com/resources-casereport.html

THE infamous v/nv CJD epidemic is only a small part of a much larger problem in this political arena of human/animal TSEs. They are only kidding themselves. ...TSS


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