Canada cattle confined after suspect feed case
Fri Dec 8, 2006 1:40 PM EST
WINNIPEG, Manitoba (Reuters) - More than 10,000 Canadian cattle remained confined on Friday to farms that received suspect feed last month, although Canada's chief veterinarian said it was extremely unlikely the feed could cause mad cow disease.
The cattle are on 113 farms in Ontario and Quebec that received feed with an ingredient that may have contained trace amounts of meat and bone meal made from cattle.
Since 1997, Canada has banned meat and bone meal from feed for cattle and other ruminant livestock because of the risk of spreading bovine spongiform encephalopathy, or mad cow disease.
Canada's detailed investigation into the feed ban infraction is now being reviewed by scientific experts in Europe and Asia, said Brian Evans, chief veterinarian at the Canadian Food Inspection Agency.
"The potential that these animals could develop BSE over time is remote. One cannot say zero, and that's the reason by which precautionary measures have been taken," Evans said in an interview.
Canada has had eight cases of mad cow disease in its domestic herd since May 2003, and hopes to eliminate the disease within a decade by tightening its feed rules.
Humans can develop a rare form of the fatal disease from eating contaminated meat, and 200 people have died from it, mainly in Britain, which experienced an outbreak of BSE in the 1980s.
Last month, Cargill Ltd. notified the CFIA that it had shipped a feed ingredient in a rail car that had not been completely cleaned out after previously containing meat and bone meal.
"The material of meat and bone meal that might have been present there was measurable in a matter of pounds: it wasn't a significant level of contamination," Evans said.
The CFIA's investigation found the meat and bone meal came from a slaughter plant that handled only young, healthy cattle unlikely to have developed mad cow disease, which takes an average of four to seven years to incubate.
The feed ingredient shipped in the rail car was added to the top of a feed mill's storage silo, and may not actually have been added to any feed rations before the mistake was uncovered, Evans said.
Cargill quickly recalled and destroyed the feed, he said.
About 80 percent of the livestock on the farms that received the feed were dairy cattle, and about 70 percent of the livestock were older animals, which are less susceptible to BSE, Evans said.
All the livestock have been permanently identified using Canada's national tracing system so that the CFIA can track them over their life spans, he said.
The livestock can be slaughtered and consumed in Canada, where food safety rules ban all brains, spines and other material that can harbor mad cow disease.
The meat might not be eligible for export, Evans said, depending on the technical requirements of importers.
In the short term, farmers are not allowed to otherwise sell or move the animals from their farms, Evans said.
"We're now starting to look at what are the other options that can be applied in segregating animals based on potential risk," he said.
Farmers have been patient, although they have some concern that their livestock may have a "stigma" because of the investigation, he said.
A spokesman for Cargill said the company has informed farmer-customers that it will help them through the process.
"We will ensure that our customers are not unfairly harmed by this, economically or otherwise," Rob Meijer said.
Cargill's suppliers have voluntarily started to use dedicated rail cars for shipping feed ingredients, he said.
The CFIA continues to review Cargill's procedures.
© Reuters 2006. All Rights Reserved.
http://ca.today.reuters.com/news/newsAr ... ived=False
http://ca.today.reuters.com/news/NewsAr ... =1&summit=
##################### Bovine Spongiform Encephalopathy #####################
Subject: POTENTIAL CJD CLUSTER IN 3 MANITOBANS, another coincidence of more spontaneous BSe
Date: December 8, 2006 at 7:29 am PST
Curler among 3 Manitobans suspected of having CJD
Last Updated: Friday, December 8, 2006 | 9:05 AM ET
CBC News
Three Manitobans — including a prominent men's curler — are suspected of having the brain-wasting disease Creutzfeldt-Jakob.
Doctors from the Brandon Regional Health Authority have referred three suspected cases of CJD for further testing. They include Neil Andrews, 58, a two-time senior provincial curling champion from Brandon.
Dr. Charles Penner said he doesn't believe the cases are linked, but added that a cluster of cases is even rarer than CJD itself.
As of Nov. 1, six cases of CJD have been reported in Canada this year, says the Public Health Agency of Canada. Since 1997, 720 cases of the degenerative and fatal disease have been referred to the agency.
Andrews was diagnosed with a suspected case of CJD in September, after he had trouble keeping his balance while curling. Doctors at the Mayo Clinic in Rochester, Minn., later told him he likely had CJD.
Earlier this week, a hospital in London, Ont., suspended surgeries for two days when one neurosurgery patient was suspected of having CJD. Preliminary test results came back negative on Tuesday.
About 30 cases of "classical" CJD are diagnosed in Canada every year.
It's the more common, sporadic of two types of CJD, which occurs spontaneously, sometimes because the disease is hereditary. Less than one per cent of the time, it is contracted through hospital or medical procedures.
The second type, variant CJD, is associated with mad-cow disease.
With files from the Canadian Press
http://www.cbc.ca/sports/story/2006/12/08/mba-cjd.html
Human version of mad cow hits Manitoba
Three cases suspected from same area in province
The Canadian Press
Published: Friday, December 08, 2006
BRANDON, Man. - Three people in Manitoba, including prominent provincial curler Neil Andrews, are suspected of being infected with a degenerative and fatal brain disease, health officials confirmed Thursday.
Doctors from the Brandon Health Region said they have referred three suspected cases of Creutzfeld-Jakob disease, or CJD, for further testing.
CJD infects about one person in every million.
The facts on CJD
Q&A about mad cow and CJD
Mad cow protein may play role in diabetes
More Body & Health news
Dr. Charles Penner, vice-president of medical services for the Brandon Regional Health Authority, doesn't believe the cases are linked, although a cluster of cases is even rarer than the disease.
"For the province to have three cases in one corner of the province, I suppose that would be unusual," he said.
Andrews, a two-time senior provincial men's curling champion, was actually diagnosed with a suspected case of CJD in September. Andrews, 58, noticed something was wrong when he had trouble keeping his balance during his curling delivery.
After a weeklong stay at the Mayo Clinic in Rochester, Minn., doctors told him he likely had CJD.
"(The curlers) knew I couldn't curl and some of them thought that before," he said, laughing, while at a curling club in Brandon in October. "And almost every guy took the time and stopped and talked to me and talked to me openly about the disease and that was good.
"They tried to understand. I'm one of the unfortunate ones who's going to die but they considered themselves lucky."
Typically, one in three suspected cases turns out to be classical CJD, which can lead to rapid brain deterioration, dementia and mobility trouble.
Unlike variant CJD, which has been linked to beef contaminated by mad cow disease, classical CJD cases most often appear sporadically and affect people between 45 and 75. A total of 14 confirmed cases has been reported in Manitoba in the last decade.
Doctors use MRI scans and spinal taps to test for the presence of an abnormal protein to help diagnose a suspected case. But physicians can't confirm anything until an autopsy on brain tissue is performed.
Most people infected with CJD die within a year of the onset of symptoms.
Dr. Michael Coulthard, director of host genetics and prion disease at the National Microbiology Lab in Winnipeg, said the results of the suspected case are still pending. He said there has only been one cluster of cases reported worldwide -- in Switzerland -- in the last five years.
© The Edmonton Journal 2006
http://www.canada.com/vancouversun/news ... 5a&k=66922
Volume 12, Number 12–December 2006
PERSPECTIVE
On the Question of Sporadic
or Atypical Bovine SpongiformEncephalopathy and
Creutzfeldt-Jakob Disease
Paul Brown,* Lisa M. McShane,† Gianluigi Zanusso,‡ and Linda Detwiler§
Strategies to investigate the possible existence of sporadic
bovine spongiform encephalopathy (BSE) require
systematic testing programs to identify cases in countries
considered to have little or no risk for orally acquired disease,
or to detect a stable occurrence of atypical cases in
countries in which orally acquired disease is disappearing.
To achieve 95% statistical confidence that the prevalence
of sporadic BSE is no greater than 1 per million (i.e., the
annual incidence of sporadic Creutzfeldt-Jakob disease
[CJD] in humans) would require negative tests in 3 million
randomly selected older cattle. A link between BSE and
sporadic CJD has been suggested on the basis of laboratory
studies but is unsupported by epidemiologic observation.
Such a link might yet be established by the discovery
of a specific molecular marker or of particular combinations
of trends over time of typical and atypical BSE and various
subtypes of sporadic CJD, as their numbers are influenced
by a continuation of current public health measures that
exclude high-risk bovine tissues from the animal and
human food chains.
SNIP...
Sporadic CJD
The possibility that at least some cases of apparently sporadic CJD might be due to infection by sporadic cases of BSE cannot be dismissed outright. Screening programs needed to identify sporadic BSE have yet to be implemented, and we know from already extant testing programs that at least a proportion of infected animals have no symptoms and thus would never be identified in the absence of systematic testing. Thus, sporadic BSE (or for that matter, sporadic disease in any mammalian species) might be occurring on a regular basis at perhaps the same annual frequency as sporadic CJD in humans, that is, in the range of 1 case per million animals.
Whether humans might be more susceptible to atypical forms of BSE cannot be answered at this time. Experimentally transmitted BASE shows shorter incubation periods than BSE in at least 1 breed of cattle, bovinized transgenic mice, and Cynomolgus monkeys (12,13). In humanized transgenic mice, BASE transmitted, whereas typical BSE did not transmit (13). Paradoxically, the other major phenotype (H) showed an unusually long incubation period in bovinized transgenic mice (12).
The limited experimental evidence bearing on a possible relationship between BSE and sporadic CJD is difficult to interpret. The original atypical BASE strain of BSE had a molecular protein signature very similar to that of 1 subtype (type 2 M/V) of sporadic CJD in humans (5). In another study, a strain of typical BSE injected into humanized mice encoding valine at codon 129 showed a glycopattern indistinguishable from the same subtype of sporadic CJD (15). In a third study, the glycopatterns of both the H and L strains of atypical BSE evidently did not resemble any of the known sporadic CJD subtypes (12).
To these molecular biology observations can be added the epidemiologic data accumulated during the past 30 years. The hypothesis that at least some cases of apparently sporadic CJD are due to unrecognized BSE infections cannot be formally refuted, but if correct, we might expect by now to have some epidemiologic evidence linking BSE to at least 1 cluster of apparently sporadic cases of CJD. Although only a few clusters have been found (and still fewer published), every proposed cluster that has been investigated has failed to show any common exposure to bovines. For that matter, no common exposure has been shown to any environmental vehicles of infection, including the consumption of foodstuffs from bovine, ovine, and porcine sources, the 3 livestock species known to be susceptible to transmissible spongiform encephalopathies. Additional negative evidence comes from several large case-control studies in which no statistically significant dietary differences were observed between patients with sporadic CJD and controls (16,17).
On the other hand, the difficulty of establishing a link between BSE and CJD may be compounded by our ignorance of the infectious parameters of a sporadic form of BSE (e.g., host range, tissue distribution of infectivity, route of transmission, minimum infectious dose for humans, whether single or multiple). Presumably, these parameters would resemble those of variant CJD; that is, high infectivity central nervous system and lymphoreticular tissues of an infected cow find their way into products consumed by humans. Transmissions that might have occurred in the past would be difficult to detect because meat products are generally not distributed in a way that results in detectable geographic clusters.
Barring the discovery of a specific molecular signature (as in variant CJD), the most convincing clue to an association will come from the observation of trends over time of the incidence of typical and atypical BSE and of sporadic and variant CJD. With 4 diseases, each of which could have increasing, unchanging, or decreasing trends, there could be 81 (34) possible different combinations. However, it is highly likely that the trends for typical BSE and variant CJD will both decrease in parallel as feed bans continue to interrupt recycled contamination. The remaining combinations are thus reduced to 9 (32), and some of them could be highly informative.
For example, if the incidence of atypical BSE declines in parallel with that of typical BSE, its candidacy as a sporadic form of disease would be eliminated (because sporadic disease would not be influenced by current measures to prevent oral infection). If, on the other hand, atypical BSE continues to occur as typical BSE disappears, this would be a strong indication that it is indeed sporadic, and if in addition at least 1 form of what is presently considered as sporadic CJD (such as the type 2 M/V subtype shown to have a Western blot signature like BASE) were to increase, this would suggest (although not prove) a causal relationship (Figure 5).
Recognition of the different forms of BSE and CJD depends upon continuing systematic testing for both bovines and humans, but bovine testing will be vulnerable to heavy pressure from industry to dismantle the program as the commercial impact of declining BSE cases ceases to be an issue. Industry should be aware, however, of the implications of sporadic BSE. Its occurrence would necessitate the indefinite retention of all of the public health measures that exclude high-risk bovine tissues from the animal and human food chains, whereas its nonoccurrence would permit tissues that are now destroyed to be used as before, once orally acquired BSE has disappeared.
SNIP...
PLEASE READ FULL TEXT ;
http://www.cdc.gov/ncidod/EID/vol12no12 ... d06_0965_e
3:00 Afternoon Refreshment Break, Poster and Exhibit Viewing in the Exhibit
Hall
3:30 Transmission of the Italian Atypical BSE (BASE) in Humanized Mouse
Models Qingzhong Kong, Ph.D., Assistant Professor, Pathology, Case Western Reserve
University
Bovine Amyloid Spongiform Encephalopathy (BASE) is an atypical BSE strain
discovered recently in Italy, and similar or different atypical BSE cases
were also reported in other countries. The infectivity and phenotypes of
these atypical BSE strains in humans are unknown. In collaboration with
Pierluigi Gambetti, as well as Maria Caramelli and her co-workers, we have
inoculated transgenic mice expressing human prion protein with brain
homogenates from BASE or BSE infected cattle. Our data shows that about half
of the BASE-inoculated mice became infected with an average incubation time
of about 19 months; in contrast, none of the BSE-inoculated mice appear to
be infected after more than 2 years. ***These results indicate that BASE is
transmissible to humans and suggest that BASE is more virulent than
classical BSE in humans.
6:30 Close of Day One
http://www.healthtech.com/2007/tse/day1.asp
SEE STEADY INCREASE IN SPORADIC CJD IN THE USA FROM
1997 TO 2006. SPORADIC CJD CASES TRIPLED, with phenotype
of 'UNKNOWN' strain growing. ...
http://www.cjdsurveillance.com/resource ... eport.html
There is a growing number of human CJD cases, and they were presented last
week in San Francisco by Luigi Gambatti(?) from his CJD surveillance
collection.
He estimates that it may be up to 14 or 15 persons which display selectively
SPRPSC and practically no detected RPRPSC proteins.
http://www.fda.gov/ohrms/dockets/ac/06/ ... 4240t1.htm
http://www.fda.gov/ohrms/dockets/ac/06/ ... 4240t1.pdf
JOURNAL OF NEUROLOGY
MARCH 26, 2003
RE-Monitoring the occurrence of emerging forms of Creutzfeldt-Jakob
disease in the United States
Email Terry S. Singeltary:
[email protected]
I lost my mother to hvCJD (Heidenhain Variant CJD). I would like to
comment on the CDC's attempts to monitor the occurrence of emerging
forms of CJD. Asante, Collinge et al [1] have reported that BSE
transmission to the 129-methionine genotype can lead to an alternate
phenotype that is indistinguishable from type 2 PrPSc, the commonest
sporadic CJD. However, CJD and all human TSEs are not reportable
nationally. CJD and all human TSEs must be made reportable in every
state and internationally. I hope that the CDC does not continue to
expect us to still believe that the 85%+ of all CJD cases which are
sporadic are all spontaneous, without route/source. We have many TSEs in
the USA in both animal and man. CWD in deer/elk is spreading rapidly and
CWD does transmit to mink, ferret, cattle, and squirrel monkey by
intracerebral inoculation. With the known incubation periods in other
TSEs, oral transmission studies of CWD may take much longer. Every
victim/family of CJD/TSEs should be asked about route and source of this
agent. To prolong this will only spread the agent and needlessly expose
others. In light of the findings of Asante and Collinge et al, there
should be drastic measures to safeguard the medical and surgical arena
from sporadic CJDs and all human TSEs. I only ponder how many sporadic
CJDs in the USA are type 2 PrPSc?
http://www.neurology.org/cgi/eletters/60/2/176#535
Diagnosis and Reporting of Creutzfeldt-Jakob Disease
Singeltary, Sr et al. JAMA.2001; 285: 733-734.
http://jama.ama-assn.org/cgi/content/fu ... lcode=jama
BRITISH MEDICAL JOURNAL
BMJ
http://www.bmj.com/cgi/eletters/319/7220/1312/b#EL2
BMJ
http://www.bmj.com/cgi/eletters/320/7226/8/b#EL1
TSS
Fri Dec 8, 2006 1:40 PM EST
WINNIPEG, Manitoba (Reuters) - More than 10,000 Canadian cattle remained confined on Friday to farms that received suspect feed last month, although Canada's chief veterinarian said it was extremely unlikely the feed could cause mad cow disease.
The cattle are on 113 farms in Ontario and Quebec that received feed with an ingredient that may have contained trace amounts of meat and bone meal made from cattle.
Since 1997, Canada has banned meat and bone meal from feed for cattle and other ruminant livestock because of the risk of spreading bovine spongiform encephalopathy, or mad cow disease.
Canada's detailed investigation into the feed ban infraction is now being reviewed by scientific experts in Europe and Asia, said Brian Evans, chief veterinarian at the Canadian Food Inspection Agency.
"The potential that these animals could develop BSE over time is remote. One cannot say zero, and that's the reason by which precautionary measures have been taken," Evans said in an interview.
Canada has had eight cases of mad cow disease in its domestic herd since May 2003, and hopes to eliminate the disease within a decade by tightening its feed rules.
Humans can develop a rare form of the fatal disease from eating contaminated meat, and 200 people have died from it, mainly in Britain, which experienced an outbreak of BSE in the 1980s.
Last month, Cargill Ltd. notified the CFIA that it had shipped a feed ingredient in a rail car that had not been completely cleaned out after previously containing meat and bone meal.
"The material of meat and bone meal that might have been present there was measurable in a matter of pounds: it wasn't a significant level of contamination," Evans said.
The CFIA's investigation found the meat and bone meal came from a slaughter plant that handled only young, healthy cattle unlikely to have developed mad cow disease, which takes an average of four to seven years to incubate.
The feed ingredient shipped in the rail car was added to the top of a feed mill's storage silo, and may not actually have been added to any feed rations before the mistake was uncovered, Evans said.
Cargill quickly recalled and destroyed the feed, he said.
About 80 percent of the livestock on the farms that received the feed were dairy cattle, and about 70 percent of the livestock were older animals, which are less susceptible to BSE, Evans said.
All the livestock have been permanently identified using Canada's national tracing system so that the CFIA can track them over their life spans, he said.
The livestock can be slaughtered and consumed in Canada, where food safety rules ban all brains, spines and other material that can harbor mad cow disease.
The meat might not be eligible for export, Evans said, depending on the technical requirements of importers.
In the short term, farmers are not allowed to otherwise sell or move the animals from their farms, Evans said.
"We're now starting to look at what are the other options that can be applied in segregating animals based on potential risk," he said.
Farmers have been patient, although they have some concern that their livestock may have a "stigma" because of the investigation, he said.
A spokesman for Cargill said the company has informed farmer-customers that it will help them through the process.
"We will ensure that our customers are not unfairly harmed by this, economically or otherwise," Rob Meijer said.
Cargill's suppliers have voluntarily started to use dedicated rail cars for shipping feed ingredients, he said.
The CFIA continues to review Cargill's procedures.
© Reuters 2006. All Rights Reserved.
http://ca.today.reuters.com/news/newsAr ... ived=False
http://ca.today.reuters.com/news/NewsAr ... =1&summit=
##################### Bovine Spongiform Encephalopathy #####################
Subject: POTENTIAL CJD CLUSTER IN 3 MANITOBANS, another coincidence of more spontaneous BSe
Date: December 8, 2006 at 7:29 am PST
Curler among 3 Manitobans suspected of having CJD
Last Updated: Friday, December 8, 2006 | 9:05 AM ET
CBC News
Three Manitobans — including a prominent men's curler — are suspected of having the brain-wasting disease Creutzfeldt-Jakob.
Doctors from the Brandon Regional Health Authority have referred three suspected cases of CJD for further testing. They include Neil Andrews, 58, a two-time senior provincial curling champion from Brandon.
Dr. Charles Penner said he doesn't believe the cases are linked, but added that a cluster of cases is even rarer than CJD itself.
As of Nov. 1, six cases of CJD have been reported in Canada this year, says the Public Health Agency of Canada. Since 1997, 720 cases of the degenerative and fatal disease have been referred to the agency.
Andrews was diagnosed with a suspected case of CJD in September, after he had trouble keeping his balance while curling. Doctors at the Mayo Clinic in Rochester, Minn., later told him he likely had CJD.
Earlier this week, a hospital in London, Ont., suspended surgeries for two days when one neurosurgery patient was suspected of having CJD. Preliminary test results came back negative on Tuesday.
About 30 cases of "classical" CJD are diagnosed in Canada every year.
It's the more common, sporadic of two types of CJD, which occurs spontaneously, sometimes because the disease is hereditary. Less than one per cent of the time, it is contracted through hospital or medical procedures.
The second type, variant CJD, is associated with mad-cow disease.
With files from the Canadian Press
http://www.cbc.ca/sports/story/2006/12/08/mba-cjd.html
Human version of mad cow hits Manitoba
Three cases suspected from same area in province
The Canadian Press
Published: Friday, December 08, 2006
BRANDON, Man. - Three people in Manitoba, including prominent provincial curler Neil Andrews, are suspected of being infected with a degenerative and fatal brain disease, health officials confirmed Thursday.
Doctors from the Brandon Health Region said they have referred three suspected cases of Creutzfeld-Jakob disease, or CJD, for further testing.
CJD infects about one person in every million.
The facts on CJD
Q&A about mad cow and CJD
Mad cow protein may play role in diabetes
More Body & Health news
Dr. Charles Penner, vice-president of medical services for the Brandon Regional Health Authority, doesn't believe the cases are linked, although a cluster of cases is even rarer than the disease.
"For the province to have three cases in one corner of the province, I suppose that would be unusual," he said.
Andrews, a two-time senior provincial men's curling champion, was actually diagnosed with a suspected case of CJD in September. Andrews, 58, noticed something was wrong when he had trouble keeping his balance during his curling delivery.
After a weeklong stay at the Mayo Clinic in Rochester, Minn., doctors told him he likely had CJD.
"(The curlers) knew I couldn't curl and some of them thought that before," he said, laughing, while at a curling club in Brandon in October. "And almost every guy took the time and stopped and talked to me and talked to me openly about the disease and that was good.
"They tried to understand. I'm one of the unfortunate ones who's going to die but they considered themselves lucky."
Typically, one in three suspected cases turns out to be classical CJD, which can lead to rapid brain deterioration, dementia and mobility trouble.
Unlike variant CJD, which has been linked to beef contaminated by mad cow disease, classical CJD cases most often appear sporadically and affect people between 45 and 75. A total of 14 confirmed cases has been reported in Manitoba in the last decade.
Doctors use MRI scans and spinal taps to test for the presence of an abnormal protein to help diagnose a suspected case. But physicians can't confirm anything until an autopsy on brain tissue is performed.
Most people infected with CJD die within a year of the onset of symptoms.
Dr. Michael Coulthard, director of host genetics and prion disease at the National Microbiology Lab in Winnipeg, said the results of the suspected case are still pending. He said there has only been one cluster of cases reported worldwide -- in Switzerland -- in the last five years.
© The Edmonton Journal 2006
http://www.canada.com/vancouversun/news ... 5a&k=66922
Volume 12, Number 12–December 2006
PERSPECTIVE
On the Question of Sporadic
or Atypical Bovine SpongiformEncephalopathy and
Creutzfeldt-Jakob Disease
Paul Brown,* Lisa M. McShane,† Gianluigi Zanusso,‡ and Linda Detwiler§
Strategies to investigate the possible existence of sporadic
bovine spongiform encephalopathy (BSE) require
systematic testing programs to identify cases in countries
considered to have little or no risk for orally acquired disease,
or to detect a stable occurrence of atypical cases in
countries in which orally acquired disease is disappearing.
To achieve 95% statistical confidence that the prevalence
of sporadic BSE is no greater than 1 per million (i.e., the
annual incidence of sporadic Creutzfeldt-Jakob disease
[CJD] in humans) would require negative tests in 3 million
randomly selected older cattle. A link between BSE and
sporadic CJD has been suggested on the basis of laboratory
studies but is unsupported by epidemiologic observation.
Such a link might yet be established by the discovery
of a specific molecular marker or of particular combinations
of trends over time of typical and atypical BSE and various
subtypes of sporadic CJD, as their numbers are influenced
by a continuation of current public health measures that
exclude high-risk bovine tissues from the animal and
human food chains.
SNIP...
Sporadic CJD
The possibility that at least some cases of apparently sporadic CJD might be due to infection by sporadic cases of BSE cannot be dismissed outright. Screening programs needed to identify sporadic BSE have yet to be implemented, and we know from already extant testing programs that at least a proportion of infected animals have no symptoms and thus would never be identified in the absence of systematic testing. Thus, sporadic BSE (or for that matter, sporadic disease in any mammalian species) might be occurring on a regular basis at perhaps the same annual frequency as sporadic CJD in humans, that is, in the range of 1 case per million animals.
Whether humans might be more susceptible to atypical forms of BSE cannot be answered at this time. Experimentally transmitted BASE shows shorter incubation periods than BSE in at least 1 breed of cattle, bovinized transgenic mice, and Cynomolgus monkeys (12,13). In humanized transgenic mice, BASE transmitted, whereas typical BSE did not transmit (13). Paradoxically, the other major phenotype (H) showed an unusually long incubation period in bovinized transgenic mice (12).
The limited experimental evidence bearing on a possible relationship between BSE and sporadic CJD is difficult to interpret. The original atypical BASE strain of BSE had a molecular protein signature very similar to that of 1 subtype (type 2 M/V) of sporadic CJD in humans (5). In another study, a strain of typical BSE injected into humanized mice encoding valine at codon 129 showed a glycopattern indistinguishable from the same subtype of sporadic CJD (15). In a third study, the glycopatterns of both the H and L strains of atypical BSE evidently did not resemble any of the known sporadic CJD subtypes (12).
To these molecular biology observations can be added the epidemiologic data accumulated during the past 30 years. The hypothesis that at least some cases of apparently sporadic CJD are due to unrecognized BSE infections cannot be formally refuted, but if correct, we might expect by now to have some epidemiologic evidence linking BSE to at least 1 cluster of apparently sporadic cases of CJD. Although only a few clusters have been found (and still fewer published), every proposed cluster that has been investigated has failed to show any common exposure to bovines. For that matter, no common exposure has been shown to any environmental vehicles of infection, including the consumption of foodstuffs from bovine, ovine, and porcine sources, the 3 livestock species known to be susceptible to transmissible spongiform encephalopathies. Additional negative evidence comes from several large case-control studies in which no statistically significant dietary differences were observed between patients with sporadic CJD and controls (16,17).
On the other hand, the difficulty of establishing a link between BSE and CJD may be compounded by our ignorance of the infectious parameters of a sporadic form of BSE (e.g., host range, tissue distribution of infectivity, route of transmission, minimum infectious dose for humans, whether single or multiple). Presumably, these parameters would resemble those of variant CJD; that is, high infectivity central nervous system and lymphoreticular tissues of an infected cow find their way into products consumed by humans. Transmissions that might have occurred in the past would be difficult to detect because meat products are generally not distributed in a way that results in detectable geographic clusters.
Barring the discovery of a specific molecular signature (as in variant CJD), the most convincing clue to an association will come from the observation of trends over time of the incidence of typical and atypical BSE and of sporadic and variant CJD. With 4 diseases, each of which could have increasing, unchanging, or decreasing trends, there could be 81 (34) possible different combinations. However, it is highly likely that the trends for typical BSE and variant CJD will both decrease in parallel as feed bans continue to interrupt recycled contamination. The remaining combinations are thus reduced to 9 (32), and some of them could be highly informative.
For example, if the incidence of atypical BSE declines in parallel with that of typical BSE, its candidacy as a sporadic form of disease would be eliminated (because sporadic disease would not be influenced by current measures to prevent oral infection). If, on the other hand, atypical BSE continues to occur as typical BSE disappears, this would be a strong indication that it is indeed sporadic, and if in addition at least 1 form of what is presently considered as sporadic CJD (such as the type 2 M/V subtype shown to have a Western blot signature like BASE) were to increase, this would suggest (although not prove) a causal relationship (Figure 5).
Recognition of the different forms of BSE and CJD depends upon continuing systematic testing for both bovines and humans, but bovine testing will be vulnerable to heavy pressure from industry to dismantle the program as the commercial impact of declining BSE cases ceases to be an issue. Industry should be aware, however, of the implications of sporadic BSE. Its occurrence would necessitate the indefinite retention of all of the public health measures that exclude high-risk bovine tissues from the animal and human food chains, whereas its nonoccurrence would permit tissues that are now destroyed to be used as before, once orally acquired BSE has disappeared.
SNIP...
PLEASE READ FULL TEXT ;
http://www.cdc.gov/ncidod/EID/vol12no12 ... d06_0965_e
3:00 Afternoon Refreshment Break, Poster and Exhibit Viewing in the Exhibit
Hall
3:30 Transmission of the Italian Atypical BSE (BASE) in Humanized Mouse
Models Qingzhong Kong, Ph.D., Assistant Professor, Pathology, Case Western Reserve
University
Bovine Amyloid Spongiform Encephalopathy (BASE) is an atypical BSE strain
discovered recently in Italy, and similar or different atypical BSE cases
were also reported in other countries. The infectivity and phenotypes of
these atypical BSE strains in humans are unknown. In collaboration with
Pierluigi Gambetti, as well as Maria Caramelli and her co-workers, we have
inoculated transgenic mice expressing human prion protein with brain
homogenates from BASE or BSE infected cattle. Our data shows that about half
of the BASE-inoculated mice became infected with an average incubation time
of about 19 months; in contrast, none of the BSE-inoculated mice appear to
be infected after more than 2 years. ***These results indicate that BASE is
transmissible to humans and suggest that BASE is more virulent than
classical BSE in humans.
6:30 Close of Day One
http://www.healthtech.com/2007/tse/day1.asp
SEE STEADY INCREASE IN SPORADIC CJD IN THE USA FROM
1997 TO 2006. SPORADIC CJD CASES TRIPLED, with phenotype
of 'UNKNOWN' strain growing. ...
http://www.cjdsurveillance.com/resource ... eport.html
There is a growing number of human CJD cases, and they were presented last
week in San Francisco by Luigi Gambatti(?) from his CJD surveillance
collection.
He estimates that it may be up to 14 or 15 persons which display selectively
SPRPSC and practically no detected RPRPSC proteins.
http://www.fda.gov/ohrms/dockets/ac/06/ ... 4240t1.htm
http://www.fda.gov/ohrms/dockets/ac/06/ ... 4240t1.pdf
JOURNAL OF NEUROLOGY
MARCH 26, 2003
RE-Monitoring the occurrence of emerging forms of Creutzfeldt-Jakob
disease in the United States
Email Terry S. Singeltary:
[email protected]
I lost my mother to hvCJD (Heidenhain Variant CJD). I would like to
comment on the CDC's attempts to monitor the occurrence of emerging
forms of CJD. Asante, Collinge et al [1] have reported that BSE
transmission to the 129-methionine genotype can lead to an alternate
phenotype that is indistinguishable from type 2 PrPSc, the commonest
sporadic CJD. However, CJD and all human TSEs are not reportable
nationally. CJD and all human TSEs must be made reportable in every
state and internationally. I hope that the CDC does not continue to
expect us to still believe that the 85%+ of all CJD cases which are
sporadic are all spontaneous, without route/source. We have many TSEs in
the USA in both animal and man. CWD in deer/elk is spreading rapidly and
CWD does transmit to mink, ferret, cattle, and squirrel monkey by
intracerebral inoculation. With the known incubation periods in other
TSEs, oral transmission studies of CWD may take much longer. Every
victim/family of CJD/TSEs should be asked about route and source of this
agent. To prolong this will only spread the agent and needlessly expose
others. In light of the findings of Asante and Collinge et al, there
should be drastic measures to safeguard the medical and surgical arena
from sporadic CJDs and all human TSEs. I only ponder how many sporadic
CJDs in the USA are type 2 PrPSc?
http://www.neurology.org/cgi/eletters/60/2/176#535
Diagnosis and Reporting of Creutzfeldt-Jakob Disease
Singeltary, Sr et al. JAMA.2001; 285: 733-734.
http://jama.ama-assn.org/cgi/content/fu ... lcode=jama
BRITISH MEDICAL JOURNAL
BMJ
http://www.bmj.com/cgi/eletters/319/7220/1312/b#EL2
BMJ
http://www.bmj.com/cgi/eletters/320/7226/8/b#EL1
TSS
