##################### 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.
2
© 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
3
© 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
4
© 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
#################### https://lists.aegee.org/bse-l.html ####################
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.
2
© 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
3
© 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
4
© 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
#################### https://lists.aegee.org/bse-l.html ####################
