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From: TSS ()
Date: April 12, 2008 at 7:26 pm PST



SEAC Annual Report 2007

The continued decline in the incidence of Bovine Spongiform Encephalopathy
(BSE) in the United Kingdom (UK) and elsewhere in Europe is very welcome. As
a result, the European Union (EU) has been able to relax some of the control
measures introduced to protect human and animal health, and is considering
further relaxations. Whilst there are clear economic benefits to relaxing
controls, the associated risks may be less well understood. During 2007,
SEAC provided advice on the risks that may be associated with changes to
specific controls, and advice on how these risks can be assessed. As the
effectiveness of one control may be related to that of others, it is
important that regulators consider the impact of specific changes, and
combinations of changes, on the effectiveness of the control regime as a
whole. Furthermore, it is vital that surveillance of animals and humans is
in place that is capable of detecting any major adverse consequences of
changes to the control regime should these arise. The recent identification
of different, albeit apparently rare, forms of BSE, which were discussed by
SEAC during the year, emphasises the need for continued vigilance.

It is highly likely that sheep were exposed to BSE during the BSE epidemic
in cattle. However, despite extensive Transmissible Spongiform
Encephalopathy (TSE) surveillance in sheep there is no evidence that BSE is
present in the UK sheep flock now. *{The relatively recent identification of
atypical scrapie and paucity of experimental data about its transmissibility
either between sheep or to humans have raised concerns about the possible
animal and public health implications of this disease}*. Although atypical
scrapie has been identified in a number of EU Member States, no clusters of
cases have been found. It is, therefore, considered that this disease may
have a low rate of transmission between sheep. It is possible, therefore,
that atypical scrapie, like classical scrapie, may have existed for some
considerable time without any apparent association with human TSEs.
Nevertheless, the human health implications need to be clarified. SEAC will
continue to monitor closely the results from research underway to assess the
human and animal health implications of atypical scrapie. Encouragingly
there was only one new diagnosed case of variant Creutzfeldt-Jakob Disease
(vCJD) in 2007. However, uncertainty remains about the number of individuals
that may be infected with vCJD but who are not showing clinical signs of the
disease (subclinical infections). It is critical to ascertain better the
prevalence of subclinical infections. This is because the assumed presence
of these infections is the reason costly interventions have been introduced
(depletion of white blood cells from blood donations, deferral of blood
recipients from donating blood and single-use instruments for certain types
of surgery and dentistry) to minimise the potential risk of human-to-human
transmission of vCJD. During 2007, SEAC reviewed the analysis of the first
tranche of results from the National Anonymous Tonsil Archive (NATA). None
of the tonsils tested to date (more than 45 000) has been found to be
positive for abnormal prion protein.

SEAC Annual Report 2007

Thus, NATA provides no evidence to suggest that a large epidemic of
subclinical infections exists. However, there is still uncertainty about how
early during the preclinical phase abnormal prion protein accumulates in
tonsil tissue and therefore, how reliably tonsil testing is able to detect
subclinical infections. It is also the case that, a large proportion of
tonsils removed comes from young people with little or no likelihood of
dietary exposure to BSE. For these reasons, SEAC continues to stress the
need for a post mortem tissue archive to complement the data from NATA.
Together NATA and a post mortem tissue archive would allow the wide range of
estimated prevalence of subclinical vCJD infections to be narrowed,
facilitating better risk assessments of potential human to human
transmission of the disease, and analyses to justify costly current and
future interventions. New risk assessments considered by SEAC during 2007
suggest that, under certain circumstances, dentistry, like blood transfusion
and surgery, may provide a route for vCJD infection to be passed between
people. Following advice from SEAC, the Department of Health issued guidance
to dentists in 2007 about making certain types of dental instruments single
use as a precautionary measure to prevent possible vCJD transmission via
certain dental procedures. SEAC strongly encourages the work already
underway to improve the decontamination of dental and surgical instruments
and to develop blood tests that will allow the risks of vCJD transmission to
be reduced. I was pleased to welcome Professors John Collinge and Azra Ghani
and Drs Richard Knight and Roland Salmon onto the committee in 2007. I was
also pleased to accept my reappointment for a second term as Chair. The
committee is very appreciative of the researchers that have shared important
unpublished data to allow SEAC and its Subgroups early consideration of
important findings. I would like to thank Kate Richards, who moved to a new
post during the year, Dr Tom Barlow who stood in as Acting SEAC Secretary,
and welcome Dr Peter Grimley as Kate?s successor as SEAC Secretary. I would
also like to thank the members of SEAC and its Subgroups for their
commitment and the expertise they bring to SEAC and the Secretariat for the
support it provides the committee.

Professor Chris Higgins Chair of SEAC

*{The relatively recent identification of atypical scrapie and paucity of
experimental data about its transmissibility either between sheep or to
humans have raised concerns about the possible animal and public health
implications of this disease}*.



Tissue distribution. For atypical scrapie, what is PrPres and
infectivity distribution within sheep of different genotypes,
particularly with respect to SRM removal? For classical
scrapie and experimental BSE in sheep, tissue distribution of
infectivity is widespread. Thus, even with SRM controls in
place, an infected sheep poses around 1000 times the risk to
human health than does an infected cow22. Does the
distribution depend on whether infection is by the oral or
21 Gubbins S. Prevalence of BSE in sheep: interpreting the results of
retrospective and
prospective testing of sheep TSE cases. SEAC 84 open meeting
22 paper presented to Food Standards Agency board on 9 December 2004.
Also see paper SEAC/84/2 Annex 2: McLean, A.
Page 13
© SEAC 27 February 2006
intracerebral route? Are some VRQ sheep carriers with no
neurological symptoms?



Aspects of the Cerebellar Neuropathology in Nor98

Gavier-Widén, D1; Benestad, SL2; Ottander, L1; Westergren, E1
1National Veterinary Insitute, Sweden; 2National Veterinary Institute,

Nor98 is a prion disease of old sheep and goats. This atypical form of
scrapie was first
described in Norway in 1998. Several features of Nor98 were shown to be
from classical scrapie including the distribution of disease associated
prion protein
(PrPd) accumulation in the brain. The cerebellum is generally the most
affected brain
area in Nor98. The study here presented aimed at adding information on the
neuropathology in the cerebellum of Nor98 naturally affected sheep of
genotypes in Sweden and Norway. A panel of histochemical and
(IHC) stainings such as IHC for PrPd, synaptophysin, glial fibrillary acidic
amyloid, and cell markers for phagocytic cells were conducted. The type of
lesions and tissue reactions were evaluated. The types of PrPd deposition
characterized. The cerebellar cortex was regularly affected, even though
there was a
variation in the severity of the lesions from case to case. Neuropil
vacuolation was
more marked in the molecular layer, but affected also the granular cell
layer. There was
a loss of granule cells. Punctate deposition of PrPd was characteristic. It
morphologically and in distribution identical with that of synaptophysin,
that PrPd accumulates in the synaptic structures. PrPd was also observed in
the granule cell layer and in the white matter. ***The pathology features of
in the cerebellum of the affected sheep showed similarities with those of
sporadic Creutzfeldt-Jakob disease in humans.

Published online before print October 20, 2005

Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0502296102
Medical Sciences

A newly identified type of scrapie agent can naturally infect sheep with
resistant PrP genotypes

( sheep prion | transgenic mice )

Annick Le Dur *, Vincent Béringue *, Olivier Andréoletti , Fabienne Reine *,
Thanh Lan Laï *, Thierry Baron , Bjørn Bratberg ¶, Jean-Luc Vilotte ||,
Pierre Sarradin **, Sylvie L. Benestad ¶, and Hubert Laude *
*Virologie Immunologie Moléculaires and ||Génétique Biochimique et
Cytogénétique, Institut National de la Recherche Agronomique, 78350
Jouy-en-Josas, France; Unité Mixte de Recherche, Institut National de la
Recherche Agronomique-Ecole Nationale Vétérinaire de Toulouse, Interactions
Hôte Agent Pathogène, 31066 Toulouse, France; Agence Française de Sécurité
Sanitaire des Aliments, Unité Agents Transmissibles Non Conventionnels,
69364 Lyon, France; **Pathologie Infectieuse et Immunologie, Institut
National de la Recherche Agronomique, 37380 Nouzilly, France; and
¶Department of Pathology, National Veterinary Institute, 0033 Oslo, Norway

Edited by Stanley B. Prusiner, University of California, San Francisco, CA,
and approved September 12, 2005 (received for review March 21, 2005)

Scrapie in small ruminants belongs to transmissible spongiform
encephalopathies (TSEs), or prion diseases, a family of fatal
neurodegenerative disorders that affect humans and animals and can transmit
within and between species by ingestion or inoculation. Conversion of the
host-encoded prion protein (PrP), normal cellular PrP (PrPc), into a
misfolded form, abnormal PrP (PrPSc), plays a key role in TSE transmission
and pathogenesis. The intensified surveillance of scrapie in the European
Union, together with the improvement of PrPSc detection techniques, has led
to the discovery of a growing number of so-called atypical scrapie cases.
These include clinical Nor98 cases first identified in Norwegian sheep on
the basis of unusual pathological and PrPSc molecular features and "cases"
that produced discordant responses in the rapid tests currently applied to
the large-scale random screening of slaughtered or fallen animals.
Worryingly, a substantial proportion of such cases involved sheep with PrP
genotypes known until now to confer natural resistance to conventional
scrapie. Here we report that both Nor98 and discordant cases, including
three sheep homozygous for the resistant PrPARR allele (A136R154R171),
efficiently transmitted the disease to transgenic mice expressing ovine PrP,
and that they shared unique biological and biochemical features upon
propagation in mice. These observations support the view that a truly
infectious TSE agent, unrecognized until recently, infects sheep and goat
flocks and may have important implications in terms of scrapie control and
public health.


Author contributions: H.L. designed research; A.L.D., V.B., O.A., F.R.,
T.L.L., J.-L.V., and H.L. performed research; T.B., B.B., P.S., and S.L.B.
contributed new reagents/analytic tools; V.B., O.A., and H.L. analyzed data;
and H.L. wrote the paper.

A.L.D. and V.B. contributed equally to this work.

To whom correspondence should be addressed.

Hubert Laude, E-mail:

Like lambs to the slaughter
31 March 2001
Debora MacKenzie
Magazine issue 2284
What if you can catch old-fashioned CJD by eating meat from a sheep infected
with scrapie?
FOUR years ago, Terry Singeltary watched his mother die horribly from a
degenerative brain disease. Doctors told him it was Alzheimer's, but
Singeltary was suspicious. The diagnosis didn't fit her violent symptoms,
and he demanded an autopsy. It showed she had died of sporadic
Creutzfeldt-Jakob disease.

Most doctors believe that sCJD is caused by a prion protein deforming by
chance into a killer. But Singeltary thinks otherwise. He is one of a number
of campaigners who say that some sCJD, like the variant CJD related to BSE,
is caused by eating meat from infected animals. Their suspicions have
focused on sheep carrying scrapie, a BSE-like disease that is widespread in
flocks across Europe and North America.

Now scientists in France have stumbled across new evidence that adds weight
to the campaigners' fears. To their complete surprise, the researchers found
that one strain of scrapie causes the same brain damage in ...

The complete article is 889 words long.

full text;

Adaptation of the bovine spongiform encephalopathy agent to primates and
comparison with Creutzfeldt- Jakob disease: Implications for human health
Corinne Ida Lasmézas*,, Jean-Guy Fournier*, Virginie Nouvel*, Hermann Boe*,
Domíníque Marcé*, François Lamoury*, Nicolas Kopp, Jean-Jacques Hauw§, James
Ironside¶, Moira Bruce, Dominique Dormont*, and Jean-Philippe Deslys*
* Commissariat à l'Energie Atomique, Service de Neurovirologie, Direction
des Sciences du Vivant/Département de Recherche Medicale, Centre de
Recherches du Service de Santé des Armées 60-68, Avenue du Général Leclerc,
BP 6, 92 265 Fontenay-aux-Roses Cedex, France; Hôpital Neurologique Pierre
Wertheimer, 59, Boulevard Pinel, 69003 Lyon, France; § Laboratoire de
Neuropathologie, Hôpital de la Salpêtrière, 83, Boulevard de l'Hôpital,
75013 Paris, France; ¶ Creutzfeldt-Jakob Disease Surveillance Unit, Western
General Hospital, Crewe Road, Edinburgh EH4 2XU, United Kingdom; and
Institute for Animal Health, Neuropathogenesis Unit, West Mains Road,
Edinburgh EH9 3JF, United Kingdom

Edited by D. Carleton Gajdusek, Centre National de la Recherche
Scientifique, Gif-sur-Yvette, France, and approved December 7, 2000
(received for review October 16, 2000)


There is substantial scientific evidence to support the notion that bovine
spongiform encephalopathy (BSE) has contaminated human beings, causing
variant Creutzfeldt-Jakob disease (vCJD). This disease has raised concerns
about the possibility of an iatrogenic secondary transmission to humans,
because the biological properties of the primate-adapted BSE agent are
unknown. We show that (i) BSE can be transmitted from primate to primate by
intravenous route in 25 months, and (ii) an iatrogenic transmission of vCJD
to humans could be readily recognized pathologically, whether it occurs by
the central or peripheral route. Strain typing in mice demonstrates that the
BSE agent adapts to macaques in the same way as it does to humans and
confirms that the BSE agent is responsible for vCJD not only in the United
Kingdom but also in France. The agent responsible for French iatrogenic
growth hormone-linked CJD taken as a control is very different from vCJD but
is similar to that found in one case of sporadic CJD and one sheep scrapie
isolate. These data will be key in identifying the origin of human cases of
prion disease, including accidental vCJD transmission, and could provide
bases for vCJD risk assessment.


typical scrapie transmits to primates by there NON-FORCED ORAL CONSUMPTION ;



This is provided by the statistically significant increase in the incidence
of sheep scrape from 1985, as determined from analyses of the submissions
made to VI Centres, and from individual case and flock incident studies.


prepared February 20, 2008

Infected and Source Flocks

There were 27 scrapie infected and source flocks with open statuses (Figure
3) as of January 31, 2008. Two new source flocks and one new infected flock
were reported in January (Figure 4) with a total of 22 reported for FY 2008
(Figure 5). ....


Positive Scrapie Cases

As of January 31, 2008, 58 new scrapie cases have been confirmed and
reported by the National Veterinary Services Laboratories (NVSL) in FY 2008
(Figure 7). Of these, 52 were field cases and 6* were Regulatory Scrapie
Slaughter Surveillance (RSSS) cases (collected in FY 2008 and reported by
February 20, 2008). There were 8 positive cases for January which are
depicted in Figure 8. Seventeen cases of scrapie in goats have been
confirmed by NVSL since implementation of the regulatory changes in FY 2002
(Figure 9). The most recent positive goat cases were from the SAME HERD and


Caprine Scrapie Prevalence Study (CSPS)

CSPS was initiated in May 2007 to estimate the national prevalance of
scrapie in adult goats at slaughter. If no scrapie is found we will be able
to conclude that the prevalence in goats is greater than zero and less than
0.1 percent. AS of January 31, 2008, 2,942 goats have been sampled for
scrapie testing (1,515 in FY 2007 and 1,427 in FY 2008). Collection numbers
by quarter in FY 2008 is shown in Chart 8. To date, no goats have tested
positive for scrapie as part of this surveillance program. HOWEVER, THREE
POSITIVE GOATS have been identified this fiscal year through field
investigations. One was a clinical suspect submitted for testing and THE


please see full text ;

full text ;


SEAC 99th meeting on Friday 14th December 2007

Friday, April 11, 2008


Friday, March 21, 2008

Association between Deposition of Beta-Amyloid and Pathological Prion
Protein in Sporadic Creutzfeldt-Jakob Disease


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