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From: TSS ()
Subject: 27 September 2005 - The summary (86 KB) of the 89th SEAC meeting held on 22nd September
Date: September 27, 2005 at 2:45 pm PST

27 September 2005 - The summary (86 KB) of the 89th SEAC meeting held on 22nd September has been published.


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EIGHTY-NINTH MEETING OF THE SPONGIFORM

ENCEPHALOPATHY ADVISORY COMMITTEE

The Spongiform Encephalopathy Advisory Committee held its 89th

meeting in London on 22nd September 2005, and discussed the

following matters:

CURRENT ISSUES

SEAC was informed about the following issues:

• The Chair will meet the Executive Director of the European

Food Safety Authority (EFSA) to develop a closer working

relationship between SEAC and EFSA.

• DH had issued draft regulations on implementation of the

Human Tissue Act for consultation. It was agreed SEAC will

provide a formal response.

• The Over Thirty Months Rule would be replaced by a BSE

testing regime, expected to take effect from 7 November

2005.

• A Medical Research Council proposal to monitor the clinical

effect of vCJD treatment with pentosan polysulphate had

recently received ethical approval.

• The Cabinet Office Public Appointments Newsletter is

planning a feature on SEAC. Members were encouraged to

participate.

• Following advice from the CJD Incidents Panel (CJDIP) DH

had notified around 100 people, identified as blood donors to

three people who later developed vCJD, that they may have a

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greater chance of being infected than the general population.

The blood donors had been asked not to donate more blood

or organs and to inform their medical practitioners before

undergoing dental or surgical treatment. The CJDIP was

currently reviewing the risk to other recipients of blood from

these donors.

• A TSE Joint Funders Group workshop, organised by the FSA,

on the research potential for ante-mortem TSE diagnostic

tests will be held on 13 – 14th December, the Chair will attend.

• Following the discussion at SEAC 88 on atypical cases of

scrapie and the possible implications for the National Scrapie

Plan, the Chair will meet Defra policy officials and Veterinary

Laboratories Agency (VLA) researchers in early November.

• A report1 of preliminary findings of natural transmission of

BSE between sheep in an experimental flock. This research

was discussed further in the reserved business session.

• A report2 describing the use of automated protein misfolding

cyclic amplification to increase the amount of abnormal prion

protein in the blood of scrapie-affected hamsters to detectable

levels. SEAC considered the method was potentially

applicable to detection of abnormal prion protein in the blood

of live animals or humans in preclinical stages of infection.

However, it would require significant further development and

evaluation. SEAC recommended that the method be

considered at the TSE Joint Funders workshop (see above).

• A very short report3 and a full report4 about the detection of

abnormal prion protein and infectivity, respectively, in parts of

the peripheral and central nervous systems (PNS and CNS) of

1 Bellworthy et al. (2005) Natural transmission of BSE between sheep within

an experimental flock. Vet. Rec. 157, 206.

2 Castilla et al. (2005) Detection of prions in blood. Nature Medicine published

online 28/08/05.

3 Iwamaru et al. (2005) PrPSc distribution of a natural case of bovine

spongiform encephalopathy. In Prions. Food and Drug Safety. Springer-

Verlag, Tokyo, 2005.

4 Buschmann & Groschup (2005) Highly Bovine Spongiform Encephalopathysensitive

transgenic mice confirm the essential restriction of infectivity to the

nervous system in clinically disease cattle. J. Infect. Dis. 192, 934-942.

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BSE cases. SEAC noted the findings were both in single

animals at the clinical stage of disease. The level of infectivity

detected in PNS tissues was considerably lower than in CNS

tissues. Further related research was discussed in the

reserved session.

EUROPEAN COMMISSION TSE ROADMAP

Defra and the FSA asked SEAC to consider a report5 describing

broad, strategic goals in relation to EU TSE policy, control and

surveillance measures. SEAC welcomed the TSE Roadmap and

made a number of recommendations, including:

• Specified risk material (SRM) controls were an important

TSE-related public health protection measure.

Amendments to SRM controls should only be reviewed in

light of emerging scientific findings.

• Appropriate feed controls are fundamental to prevent

recycling of potentially infectious material in animal feed

and prevent re-emergence of an epidemic. Any potential

changes to feed controls must therefore be considered in

this light.

• Effective surveillance to ascertain infection prevalence and

to monitor the potential effect of changes to control

measures should be maintained. Surveillance programmes

should be capable of monitoring potential changes to, or

new, TSEs, or other diseases.

• Changes to regulations in any one of the strategic areas

might impact on others, and therefore no single strategic

area should be considered in isolation.

• It would be important to communicate the reasons for any

changes to TSE legislation to consumers effectively.

Defra and FSA would seek advice from SEAC on specific

proposals as EU discussions develop.

HYPOTHESIS ON ORIGINS OF BSE

5 European Commission TSE Roadmap (15 July 2005).

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SEAC considered a paper6 presenting a hypothesis that BSE

arose from cattle feed contaminated with human remains derived

from people infected with CJD.

SEAC considered it unlikely that the origins of BSE could ever be

determined conclusively. Since human remains might have been

included in animal feed in the past, the hypothesis was plausible.

However, current EU and UK feed controls prevent such material

entering animal feed now. It is not possible to determine from

current knowledge of the characteristics of prion strains whether

BSE originated from CJD or other known prion strains. Since

much larger quantities of cattle and sheep remains had entered

animal feed historically, and there is likely to be a species barrier

between man and cattle, it seemed more likely that the origins of

BSE may be related to a TSE in these species. The committee

agreed to issue a statement about the hypothesis based on its

discussions.

SEAC EPIDEMIOLOGY SUBGROUP MEETING

The Chair of the SEAC Epidemiology Subgroup updated the

committee on the Subgroup’s second meeting. Discussions had

continued on the profile of the vCJD epidemic and the potential for

secondary transmission of vCJD. The Subgroup had reviewed

data on the prevalence of primary infection and modelling studies,

exploring possible influences of age and genotype on infection.

The Subgroup concluded that further data were required before

the outputs of the modelling work could be verified. New potential

data sources to better understand the profile of the epidemic were

considered. Approaches to assessment of possible interactions

between routes of secondary transmission were also discussed.

The Subgroup agreed to produce a position statement based on its

considerations so far and to meet next year when further modelling

work on secondary routes of transmission was completed.

BSE DVD

SEAC was shown a DVD used to train veterinary surgeons in the

clinical diagnosis of BSE. The committee welcomed this

6 Colchester & Colchester (2005) The origin of bovine spongiform

encephalopathy: the human prion disease hypothesis. Lancet. 366, 856-861.

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development and noted it would be useful to maintain knowledge

of the clinical symptoms of BSE, particularly amongst individuals

who had not had practical experience of the disease at the height

of the epidemic.

BSE IN SHEEP

Defra and FSA asked SEAC to consider preliminary findings from

a current study, set up to investigate whether BSE could spread

naturally and persist within a sheep flock, and to provide material

for other studies. The item was discussed in the reserved

business session as it involved consideration of unpublished

research.

In the study, 2 out of 15 lambs born to ewes that had been orally

dosed with BSE, had succumbed to BSE. SEAC noted that

although these preliminary findings showed that BSE had

transmitted by natural means, this had occurred in an experimental

flock under circumstances when opportunities for transmission had

been maximised. It was not possible to determine from the

information available the precise route of transmission. No change

in the BSE signature, as a result of transmission between mother

and offspring, was evident from biochemical tests.

SEAC concluded that, as the experiment was on going, it was

premature to determine the possible transmission efficiency of

BSE within a flock or whether it was sufficient to sustain an

epidemic. It was noted that BSE had not been found in on going

surveillance for scrapie, and therefore there is no evidence that

BSE currently exists in the national sheep flock. SEAC would

consider further findings from the study as they became available.

VLA RESEARCH UPDATE

SEAC was updated on current research at VLA, in particular

collaborative work with Japanese researchers to examine the

distribution of abnormal prion protein in the peripheral nervous

system of cattle with BSE. SEAC considered the data so far did

not warrant re-examination of the risk under the current SRM

regulations, but welcomed proposed experiments particularly in

animals at preclinical stages of infection. The item was discussed

in the reserved business session as it involved consideration of

unpublished research.

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http://www.seac.gov.uk/minutes/summary89.pdf

26 September 2005 - The final minutes (88 KB) of the 88th SEAC meeting held on 30th June

http://www.seac.gov.uk/whtsnew.htm

TSS



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