From: TSS (216-119-136-80.ipset16.wt.net)
Subject: Re: Docket No. 01-068-1 -- (200,000 USA DOWNERS ANNUALLY)
Date: December 4, 2003 at 1:41 pm PST
In Reply to: Re: Docket No. 01-068-1 -- (200,000 USA DOWNERS ANNUALLY) posted by N. Facklam on September 10, 2003 at 9:53 am:
Hello N. Facklam,
sorry for any confusion on the BSE/TSE testing in the USA for
mad cow disease in cattle. I have supplied more figures below
to straighten any confusion out. The numbers speak for themselves;
© Defra 2003
2
BSE cases found from active surveillance
Great Britain
5. The total number of cattle tested for BSE in all testing categories from 1
July 2001 to 31 October 2003 was 716,606 of which 1,222 (~0.17%) cases were
confirmed as BSE positive. 155,172 of this total were fallen cattle aged over 24
months of which there have been 300 (~0.20%) positive cases. 252,500
casualties have been tested with 892 (~0.36%) positive cases.
6. 129,779 healthy cattle born between August 1996 and August 1997 (the
year following the introduction of the UK’s effective feed ban) were tested
between September 2001 and 31 October 2003 with 8 positive results. Please
note that due to OTMS data being reconciled sometime after the results are first
known, minor changes may occur in this test category.
7. Across all the surveys a total of 173,823 animals born during the August
1996 - August 1997 window have been tested with 27 (~0.02%) positive
results, one of which was from an imported animal.
8. The survey of 50,000 randomly selected OTMS animals which operated
from December 2001 has now largely been subsumed by a new requirement,
contained in Commission Regulation 1494/2002, that the UK test all cattle born
after August 1996 and aged over 42 months. There remains a requirement for
the UK to randomly select and test an annual 10,000 pre-August 1996 cattle.
19,473 of these random animals were tested between December 2001 and 31
October 2003, with 16 (0.09%) positive results.
9. A total of 155,806 healthy cattle aged over 42 months and born after
August 1997 were tested between December 2001 and 31 October 2003, with 6
positive results.
10. Between January 2002 and 31 October 2003, 95,922 sheep aged over 18
months and presented for slaughter at fresh meat abattoirs were tested for
scrapie with 68 positive results confirmed. 4,190 fallen (dead on farm) sheep
were tested during this period with 14 scrapie positive results.
11. As at 31 October 2003, 171 goats had been tested under an abattoir
survey of 240 animals aged over 18 months with none testing positive for
scrapie. 44 fallen (dead on farm) goats were also tested during this period with
no positive results.
Northern Ireland
12. By 31 October 2003, test results confirmed BSE in 41 animals tested
under the cattle testing programme. 36 of the confirmed cases were casualty
animals, 3 were fallen stock, 1 was a random OTMS animal and 1 was an antemortem
failure. Further information is included in Annex A.
snip...
http://www.defra.gov.uk/animalh/bse/bse-publications/monrep/monrep67.pdf
The following figures are for BSE in Great Britain (excluding the Channel Islands and Isle of Man) unless otherwise indicated.
Weekly Statistics
* Passive surveillance figures - 14 November 2003
http://www.defra.gov.uk/animalh/bse/bse-statistics/level-4-weekly-stats.html#pass
* Active surveillance figures - 14 November 2003
http://www.defra.gov.uk/animalh/bse/bse-statistics/level-4-weekly-stats.html#act
BSE TESTING Cumulative table from January to August 2003
http://europa.eu.int/comm/food/fs/bse/testing/bse_cumul_08-03_en.pdf
As of September 30, 2003, a TOTAL (since inception of BSE surveillance
program began, some 13 years ago) ONLY 57,000+ brains have ever been
examined for BSE or another form of a TSE in cattle in the United States.
http://www.aphis.usda.gov/lpa/issues/bse/bse-surveillance.html
PAST figures in the USA infamous BSE/TSE testing program are not
much more reassuring;
From: Lisa.A.Ferguson@netlink.co.nz
To: tse-conference@netlink.co.nz
Subject: TSE Conference: BSE SURVEILLANCE IN THE UNITED STATES
Sender: owner-tse-conference@netlink.co.nz
BSE SURVEILLANCE IN THE UNITED STATES
Lisa A. Ferguson, DVM
USDA, APHIS, VS
Import/Export Staff
BSE does not occur in the United States, and USDA has
worked aggressively and proactively since 1989 to keep it
that way. The measures APHIS has taken in this regard
include prohibitions and/or restrictions on certain animal and
product imports; ongoing surveillance for signs of the
disease in the United States; preparation of an emergency
response plan in the unlikely event an introduction were to
occur; and ongoing educational efforts. APHIS actively
shares information and coordinates closely with other Federal
agencies, as well as the States, livestock and affiliated
industries, veterinary and research communities, and
consumer groups, in order to ensure that the US has a
uniform approach to transmissible spongiform
encephalopathies which is based on sound scientific
information.
APHIS has a comprehensive surveillance program in place in
the United States to ensure timely detection and swift
response in the unlikely event that an introduction of BSE
were to occur. This surveillance program incorporates both
the location of imports from the United Kingdom and targeted
active and passive surveillance for either BSE or any other
TSE in cattle.
APHIS has conducted a traceback effort to locate each of the
496 British cattle that were imported into this country
between January 1, 1981 and July 1989. In July 1989, the
U.S. prohibited the importation of ruminants from countries
affected with BSE. Only 25 of these animals are known to
be alive in the United States, and these animals are being
carefully monitored by APHIS personnel on an ongoing basis.
APHIS continues to purchase these animals for diagnostic
purposes. No evidence of BSE has been found in any of
these imported animals.
The United States has had an aggressive and active
surveillance program for BSE in place since May 1990.
BSE is a notifiable disease, and there are more than 250
federal and state regulatory veterinarians specially trained to
diagnose foreign animals diseases, including BSE. There
are several agencies involved in the surveillance program,
including the Food Safety Inspection Service (FSIS) and the
Centers for Disease Control (CDC), and APHIS leads this
interagency effort. The surveillance samples include field
cases of cattle exhibiting signs of neurological disease,
cattle condemned at slaughter for neurological reasons,
rabies-negative cattle submitted to public health laboratories,
neurological cases submitted to veterinary diagnostic
laboratories and teaching hospitals, and random sampling of
cattle which are non-ambulatory at slaughter.
As of March 31, 1997, a total of 5,552 brains had been
examined for BSE or another form of a transmissible
spongiform encephalopathy in cattle. Eight hundred and
ninety-eight of these were non-ambulatory. No evidence of
either condition has been found.
Targeted active surveillance:
Initial risk analyses were performed in 1991 to assess the
risk factors associated with BSE. These risk factor analyses
have been updated as necessary based on additional
scientific findings that have been released, and have
continued to demonstrate that the overall risk of BSE in the
US is extremely low and is decreasing. These risk analyses
have also been used to identify the portion of the cattle
industry which would be at the highest risk of contracting
BSE, and this population is where the majority of the active
surveillance (brain submission and examination) has
occurred. Specifically, this surveillance has been targeted
at adult animals which demonstrated neurological
abnormalities or animals which were non-ambulatory at
slaughter.
No evidence of BSE has been found in this sampling from the
highest risk population, either through histological
examination or immunohistochemistry.
The following calculations can be used to define the
maximum incidence of BSE in the US at current surveillance
levels. These calculations are based on assumptions
explained as follows:
(1) The cattle population of the US is as listed in the
attached table. Dairy cow inventory is 9.4 million, beef cow
inventory is 35.6 million, and the total number of adult cows
and bulls is 47.4 million.
(2) An estimate of cows exhibiting central nervous
system abnormalities can be extrapolated from the NAHMS
Dairy 96 Study. This study asked producers to answer a
question about the number of 'cows that died on farm due to
lack of coordination or severe depression.' This estimate is
0.1%.
(3) The NAHMS April 96 BSE Implications update
calculated that an average of 645 brains had been sampled
annually over the previous two years. Sampling has
increased over the past year, so for the purposes of this
calculation we are assuming that the current sampling rate is
750-1,000 annually.
The fact that no evidence of BSE has been found in the 5,552
brains examined to date provides the basis for an estimate of
the maximum potential incidence of BSE in the US.
Assume that we sample from the population of adult dairy
cows with CNS signs and we expect that the disease occurs
only in this population. The size of the population from
which we are sampling would be 9,400 (0.1% of 9.4 million).
If 750 animals are sampled annually, the maximum number
of diseased animals would be 37. If we then divide this figure
by the total population of all adult cows and bulls, the
maximum incidence would be 0.7 per 1 million. This figure
is at 95% confidence. If we sample from the population of
adult beef and dairy cows with CNS signs, the maximum
incidence would be 3 per million. The risk of disease in the
beef cow population is lower than the dairy cow population,
due to differences in management practices, and therefore
this figure can be assumed to be slightly high.
We can also calculate the number of animals needed to
sample to be 90% (95%) certain that the incidence is no
greater than 1 in 1,000,000. If the incidence in the population
of all adult cows and bulls is 1 per million, then we would
expect 47 diseased animals per year. If we assume
that these 47 animals can only come from the population of
adult dairy cows with CNS signs, then 450 cows would need
to be sampled annually to be 90% certain that the incidence
in the population of all adult cows and bulls is no greater than
1 per million. A total of 580 cows would need to be
sampled to achieve a 95% confidence level. If we assume
that the 47 diseased animals can come from the entire
population of all adult cows and bulls, then 2.25 million
animals would need to be sampled annually for a 90%
confidence level, and 2.9 million would be necessary for a
95% confidence level. These figures, based on the entire
population, are unrealistic to obtain, so the active surveillance
program has been targeted at the highest risk population -
specifically, the adult cattle population with CNS signs.
These brain submissions are examined using both
histological examination and immunohistochemistry.
Laboratories began using immunohistochemistry in 1994,
and have increased the percentage of samples tested with
this method since then. Currently we are attempting to
evaluate all of the samples submitted utilizing both
histopathology and immunohistochemistry.
General surveillance:
In addition to this active surveillance as described, general
surveillance takes advantage of existing data sources.
These sources include a database maintained at Purdue
University with diagnoses submitted from 27 U.S. veterinary
schools, CNS antemortem condemnation data from FSIS,
necropsies performed at zoos on various species, and a
veterinary diagnostic lab reporting system. Also, referrals of
unusual cases by private practitioners to veterinary schools
and diagnostic laboratories provides additional surveillance.
Through all of these sources, there has been no reported
appearance of a new neurologic disease in cattle, nor does
there appear to be an increase in the number of neurologic
diagnoses or referrals.
Other risk factors:
Import controls:
APHIS has restricted the importation of live ruminants from
countries where BSE is known to exist in native cattle since
1989. Other products derived from ruminants, such as fetal
bovine serum, bone meal, meat and bone meal, blood meal,
offal, fats, and glands, also are restricted from entry, except
under special permit for scientific or research purposes or
under special conditions to be used in cosmetics.
APHIS regulations allow for the entry of beef, under certain
conditions, from countries where BSE is known to exist.
This meat must be deboned, with visible lymphatic and
nervous tissue removed; it must be obtained from ruminants
which have undergone veterinary examination prior to
slaughter; and it must be obtained from ruminant that have
not been in any country in which BSE has been reported
during the period of time when that country permitted the use
of ruminant protein in ruminant feed. Even with these
regulations in place, there have been no beef imports from
the United Kingdom since 1985.
Feeding and management practices:
The initial risk analyses done by APHIS in 1991 described
significant differences in feeding and management practices
between the United States and the United Kingdom which
are believed to be important in decreasing the risk of BSE.
The United States feeds more concentrates and has an
abundance of plant-based proteins such as soybean meal
and cottonseed meal. Therefore, the portion of animal
proteins used as a percent of all other major feed proteins
has been significantly less in the United States. Another
critical difference was the inclusion of meat and bone meal
as a protein source in calf starter feeds in the UK, prior to the
feeding bans. Comparable feeds in the US contain plant
based proteins.
The United States has an abundance of cattle and relatively
few sheep - approximately 8.5 million sheep to 100 million
cattle. This is in contrast to the situation in the United
Kingdom, where the ratio of sheep to cattle is 32 times
greater. Sheep make up approximately 1.5 percent of
ruminant meat production in the U.S., with mature sheep
accounting for about 6 percent of sheep slaughter in the
U.S.. The amount of sheep offal is approximately 0.6
percent of all U.S. rendered product, compared to an
estimate of 14 percent of U.K. rendered product. The amount
of mature sheep offal is approximately 0.1 percent of all U.S.
rendered product. To measure potential risk from sheep
meat and bone meal, the ratio of diary concentrate fed to
mature sheep meat and bone meal produced must be
considered. A larger ratio means a greater dilution and
therefore less potential risk. In the United States, the ratio is
34,760:1, or over 17 tons of dairy concentrate fed to each
pound of sheep meat and bone meal produced. This is in
contrast to the figures in the United Kingdom, where the ratio
was 778:1. As an additional note, the incidence of scrapie
in the United States is relatively low, and some form of a
scrapie control or eradication program has been in place in
the U.S. since 1952.
In 1989, the rendering industry in the US suggested a
voluntary ban on rendering adult sheep and selling the
rendered product for use in cattle feed. This industry ban
appeared to have a fairly high compliance rate. On January
3, 1997, the FDA published a proposed rule which would
prohibit the use of protein derived from ruminant and mink
tissues in ruminant feed. The comment period on this
proposal closed February 18, 1997. In April the FDA
published a proposal to prohibit the use of most mammalian
proteins in ruminant feeds.
Conclusion:
The combination of all of these factors, including both active
and general surveillance, has shown no evidence that BSE
exists in the United States. The targeted surveillance
especially, with a total number of 5,552 brains examined
since 1990 and an average of at least 650 brains examined
annually over the last 3 years, demonstrates the fact that
BSE is not known to exist in the United States.
Cattle and Calves: Number by Class and Calf Crop - 1996
(1,000 head)
Cattle and calves (total) 112,000
Cows that have calved 45,000
Beef 35,600
Dairy 9,400
Heifers 500 pounds and over 17,300
Steers 500 pounds and over 15,400
Bulls 500 pounds and over 2,400
Calves less than 500 pounds 31,900
Calf crop 39,800
Source: Cattle: July 1996; Agricultural Statistics Board,
NASS, USDA
********************************TEXT ENDS HERE*******
consider all the above to the following;
Gerald Wells: Report of the Visit to USA, April-May 1989
snip...
The general opinion of those present was that BSE, as an
overt disease phenomenon, _could exist in the USA, but if it did,
it was very rare. The need for improved and specific surveillance
methods to detect it as recognised...
snip...
It is clear that USDA have little information and _no_ regulatory
responsibility for rendering plants in the US...
snip...
3. Prof. A. Robertson gave a brief account of BSE. The US approach
was to accord it a _very low profile indeed_. Dr. A Thiermann showed
the picture in the ''Independent'' with cattle being incinerated and thought
this was a fanatical incident to be _avoided_ in the US _at all costs_...
snip...
http://www.bseinquiry.gov.uk/files/mb/m11b/tab01.pdf
To be published in the Proceedings of the
Fourth International Scientific Congress in
Fur Animal Production. Toronto, Canada,
August 21-28, 1988
Evidence That Transmissible Mink Encephalopathy
Results from Feeding Infected Cattle
R.F. Marsh* and G.R. Hartsough
•Department of Veterinary Science, University of Wisconsin-Madison, Madison,
Wisconsin 53706; and ^Emba/Creat Lakes Ranch Service, Thiensville, Wisconsin 53092
ABSTRACT
Epidemiologic investigation of a new incidence of
transmissible mink encephalopathy (TME) in Stetsonville, Wisconsin
suggests that the disease may have resulted from feeding infected
cattle to mink. This observation is supported by the transmission of
a TME-like disease to experimentally inoculated cattle, and by the
recent report of a new bovine spongiform encephalopathy in
England.
INTRODUCTION
Transmissible mink encephalopathy (TME) was first reported in 1965 by Hartsough
and Burger who demonstrated that the disease was transmissible with a long incubation
period, and that affected mink had a spongiform encephalopathy similar to that found in
scrapie-affecied sheep (Hartsough and Burger, 1965; Burger and Hartsough, 1965).
Because of the similarity between TME and scrapie, and the subsequent finding that the
two transmissible agents were indistinguishable (Marsh and Hanson, 1969), it was
concluded that TME most likely resulted from feeding mink scrapie-infecied sheep.
The experimental transmission of sheep scrapie to mink (Hanson et al., 1971)
confirmed the close association of TME and scrapie, but at the same time provided
evidence that they may be different. Epidemiologic studies on previous incidences of
TME indicated that the incubation periods in field cases were between six months and
one year in length (Harxsough and Burger, 1965). Experimentally, scrapie could not be
transmitted to mink in less than one year.
To investigate the possibility that TME may be caused by a (particular strain of
scrapie which might be highly pathogenic for mink, 21 different strains of the scrapie
agent, including their sheep or goat sources, were inoculated into a total of 61 mink.
Only one mink developed a progressive neurologic disease after an incubation period of
22 mon..s (Marsh and Hanson, 1979). These results indicated that TME was either caused
by a strain of sheep scrapie not yet tested, or was due to exposure to a scrapie-like agent
from an unidentified source.
OBSERVATIONS AND RESULTS
A New Incidence of TME. In April of 1985, a mink rancher in Stetsonville, Wisconsin
reported that many of his mink were "acting funny", and some had died. At this time, we
visited the farm and found that approximately 10% of all adult mink were showing
typical signs of TME: insidious onset characterized by subtle behavioral changes, loss of
normal habits of cleanliness, deposition of droppings throughout the pen rather than in a
single area, hyperexcitability, difficulty in chewing and swallowing, and tails arched over
their _backs like squirrels. These signs were followed by progressive deterioration of
neurologic function beginning with locomoior incoordination, long periods of somnolence
in which the affected mink would stand motionless with its head in the corner of the
cage, complete debilitation, and death. Over the next 8-10 weeks, approximately 40% of
all the adult mink on the farm died from TME.
Since previous incidences of TME were associated with common or shared feeding
practices, we obtained a careful history of feed ingredients used over the past 12-18
months. The rancher was a "dead stock" feeder using mostly (>95%) downer or dead dairy
cattle and a few horses. Sheep had never been fed.
Experimental Transmission. The clinical diagnosis of TME was confirmed by
histopaihologic examination and by experimental transmission to mink after incubation
periods of four months. To investigate the possible involvement of cattle in this disease
cycle, two six-week old castrated Holstein bull calves were inoculated intracerebrally
with a brain suspension from affected mink. Each developed a fatal spongiform
encephalopathy after incubation periods of 18 and 19 months.
DISCUSSION
These findings suggest that TME may result from feeding mink infected cattle and
we have alerted bovine practitioners that there may exist an as yet unrecognized
scrapie-like disease of cattle in the United States (Marsh and Hartsough, 1986). A new
bovine spongiform encephalopathy has recently been reported in England (Wells et al.,
1987), and investigators are presently studying its transmissibility and possible
relationship to scrapie. Because this new bovine disease in England is characterized by
behavioral changes, hyperexcitability, and agressiveness, it is very likely it would be
confused with rabies in the United Stales and not be diagnosed. Presently, brains from
cattle in the United States which are suspected of rabies infection are only tested with
anti-rabies virus antibody and are not examined histopathologically for lesions of
spongiform encephalopathy.
We are presently pursuing additional studies to further examine the possible
involvement of cattle in the epidemiology of TME. One of these is the backpassage of
our experimental bovine encephalopathy to mink. Because (here are as yet no agent-
specific proteins or nucleic acids identified for these transmissible neuropathogens, one
means of distinguishing them is by animal passage and selection of the biotype which
grows best in a particular host. This procedure has been used to separate hamster-
adapted and mink-udapted TME agents (Marsh and Hanson, 1979). The intracerebral
backpassage of the experimental bovine agent resulted in incubations of only four months
indicating no de-adaptation of the Stetsonville agent for mink after bovine passage.
Mink fed infected bovine brain remain normal after six months. It will be essential to
demonstrate oral transmission fiom bovine to mink it this proposed epidemiologic
association is to be confirmed.
ACKNOWLEDGEMENTS
These studies were supported by the College of Agricultural and Life Sciences,
University of Wisconsin-Madison and by a grant (85-CRCR-1-1812) from the United
States Department of Agriculture. The authors also wish to acknowledge the help and
encouragement of Robert Hanson who died during the course of these investigations.
REFERENCES
Burger, D. and Hartsough, G.R. 1965. Encephalopathy of mink. II. Experimental and
natural transmission. J. Infec. Dis. 115:393-399.
Hanson, R.P., Eckroade, R.3., Marsh, R.F., ZuRhein, C.M., Kanitz, C.L. and Gustatson,
D.P. 1971. Susceptibility of mink to sheep scrapie. Science 172:859-861.
Hansough, G.R. and Burger, D. 1965. Encephalopathy of mink. I. Epizoociologic and
clinical observations. 3. Infec. Dis. 115:387-392.
Marsh, R.F. and Hanson, R.P. 1969. Physical and chemical properties of the
transmissible mink encephalopathy agent. 3. ViroL 3:176-180.
Marsh, R.F. and Hanson, R.P. 1979. On the origin of transmissible mink
encephalopathy. In Hadlow, W.J. and Prusiner, S.P. (eds.) Slow transmissible
diseases of the nervous system. Vol. 1, Academic Press, New York, pp 451-460.
Marsh, R.F. and Hartsough, G.R. 1986. Is there a scrapie-like disease in cattle?
Proceedings of the Seventh Annual Western Conference for Food Animal Veterinary
Medicine. University of Arizona, pp 20.
Wells, G.A.H., Scott, A.C., Johnson, C.T., Cunning, R.F., Hancock, R.D., Jeffrey, M.,
Dawson, M. and Bradley, R. 1987. A novel progressive spongiform encephalopathy
in cattle. Vet. Rec. 121:419-420.
MARSH
http://www.bseinquiry.gov.uk/files/mb/m09/tab05.pdf
TSS
