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From: TSS ()
Date: April 16, 2008 at 2:15 pm PST



On December 9, 2007 a cow located on a commercial beef farm in East Central
Alberta was destroyed following an illness of approximately three and a half
months duration. A private practitioner sampled the animal on December 9,
2007 under Canada's National BSE Surveillance Program. On December 11, 2007,
brain samples were received by the National BSE Reference Laboratory in
Lethbridge, AB, where they were screened for BSE using a Prionics-check
priostrip test. The result of this preliminary test did not rule out BSE. In
accordance with the prescribed testing protocol, the test was repeated and
produced a second reaction that day. Additional rapid screening tests
(Prionics-Check Western, Bio-Rad Elisa and Hybrid Western Blot) conducted at
the National BSE Reference Laboratory, were positive on December 12, 2007
and December 13, 2007, respectively. The Scrapie Associated Fibril
Immunoblot was positive on December 14, 2007 and on December 17, 2007, the
immunohistochemistry procedure was positive. The carcass was secured at the
sampling site, and was subsequently transferred to the CFIA Laboratory in
Lethbridge for incineration. No part of the carcass entered the human food
supply or animal feed chain.

The CFIA immediately initiated an epidemiological investigation based on the
most recent recommended BSE guidelines of the World Organisation for Animal
Health, referred to as OIE. Specifically, the CFIA followed the recommended
guidelines for a country with controlled BSE risk status and investigated:

the feed cohort, comprising all cattle which, during their first year of
life, were reared with the BSE cases during their first year of life, and
which investigation showed consumed the same potentially contaminated feed
during that period, or
the birth cohort, comprising all cattle born in the same herd as, and within
12 months of the birth of, the BSE cases, if the above cannot be identified.
Animal Investigation
The positive animal was an unregistered Hereford cow born on March 15, 1994
and was 165 months of age at the time of death. The age of the animal
complicated the investigation because it exceeded the normal information
retention period of the commercial enterprises involved (for example,
auction records are normally kept for seven years). However, farm records
were extensive and indicated the case animal was born, raised and had spent
its entire life on the same farm. The producer reported that the cow had
been ill for approximately three and a half months and that prior to death
was lame and had an abnormal posture. The producer determined that the
animal should be destroyed, and a private veterinary practitioner attended
the premises to determine if the animal met the inclusion criteria of
Canada's National BSE Surveillance Program. Since the inclusion criteria of
Canada?s National BSE Surveillance Program were met, arrangements were made
to forward appropriate samples for laboratory evaluation. A post-mortem
examination was conducted, abdominal adhesions were observed, and a
presumptive diagnosis of peritonitis was made by the submitting

The case premises is a beef cow-calf operation. The operation has both a
purebred and commercial component. The birth cohort was determined to
comprise 357 animals, which, along with the case animal, were born on the
birth farm. This includes male and female animals born from March 15, 1993
to March 15, 1995. Both sexes were included as they had access to the same
commercially prepared feeds and may have been exposed to the same
potentially contaminated feed as the case animal. During the time period of
interest, no animals one year of age or less were purchased. All
replacements were sourced from the producer?s own calf crop. Therefore,
there were no additional feed cohorts.

The trace-out investigation of the cohort located eight live animals on the
premises and in one other herd. The eight animals have been humanely
destroyed, and their carcasses were disposed of along with the case animal?s
by incineration, in accordance with OIE recommendations.

Because the cohort cattle would now be 13-15 years of age, most had
previously been slaughtered or died of natural causes. The following is the
disposition of the remaining 349 animals:

81 animals were traced and confirmed to have died or been slaughtered,
254 animals were traced and presumed to have died or been slaughtered,
14 animals were determined to be untraceable due to incomplete records.
The investigation revealed that the case animal had two calves born within
the previous two years. The CFIA no longer requires the destruction of
calves of BSE positive cows born within 24 months of the development of
clinical signs, in accordance with the current Bovine Spongiform
Encephalopathy Chapter of the OIE Terrestrial Animal Health Code (2007).
However, the CFIA continues to trace calves born to a positive female in
respect of the current export certification requirements of some importing
countries. The 2006 progeny was confirmed to have been slaughtered and the
2007 progeny was located on the case farm and was humanely destroyed to
ensure Canada?s continued compliance with current export certification
requirements. Its carcass was incinerated at the CFIA Lethbridge Laboratory.

Feed Investigation
The feed investigation yielded limited records specific to the animal?s
first year of life. A probable feeding regime was identified through
recollection of standard feeding practices and an index of feed products
used was developed based on invoices available for the period when the
animal was 10 - 20 months of age. These records provided the basis for
determining the types of products used and the feed suppliers with which a
business relationship existed.

Review of the information identified feeding practices consistent with an
operation of this type. The case animal was reported to have remained with
its dam from time of birth through to weaning at approximately eight months
of age. Prior to weaning, the animal was kept on community pasture and had
access to mineral feed products. At the time of weaning, the animal was
removed from pasture and fed farm-harvested forage as well as a farm-mixed
ration comprised of farm-grown grains, commercial protein supplement, and/or
mineral feed products. Feeding of this type of product continued through to
approximately 13 months of age.

Other feed products identified on the farm but not directly linked to the
subject animal included milk replacer and commercially prepared complete
feed. Commercial feed products (minerals, milk replacers, protein
supplements, complete rations) were purchased from a variety of suppliers
and represented all identified businesses within the trading area.

The period of interest of this feed investigation, pre-dates the
implementation of Canada?s initial ruminant feed ban in August of 1997. The
age of the animal further limited the investigation as the time period
exceeded normal information retention periods. As a result trace back
inspections at the suppliers and manufacturers of commercial feeds
distributed to the birth farm did not yield specific distribution records or
mixing formulas for the time frame of interest. Three of four possible
manufacturers supplying a protein supplement likely fed to the animal could
have included meat and bone meal (MBM) as an ingredient in its formulation.
One of these manufacturers was able to confirm usage of meat and bone meal
in supplements and confirm a source of MBM to be one common to previous BSE
investigations. This information is consistent with the commercial feed
industry?s practice of using of meat and bone meal as a source of protein in
livestock feeds at the time (prior to the 1997 Feed Ban).

A review of the common feeding and manufacturing practices indicates
probable exposure to infectious material through a commercial feed
supplement containing meat and bone meal.

Investigation Overview
Canada?s eleventh case of BSE has been attributed to a less prevalent,
atypical strain of BSE which has also been reported in Europe. This is the
second case of BSE in Canada that has involved an atypical strain. A common
feature of atypical BSE cases is that the affected animals are of an
advanced age at the time of diagnosis (for example, both of Canada?s
atypical cases involved cattle that were over 13 years of age at the time
BSE was confirmed). This is in contrast to Canada?s classical BSE cases
where the average age has been approximately 6 years.

The identification of these atypical strains of BSE is a reflection of an
increased global awareness of the potential for multiple strains of the BSE
agent to exist, continuous advancements in diagnostic test methods and is a
direct result of the enhanced BSE surveillance activities occurring

Since the confirmation of BSE in a native-born animal in May 2003, Canada
has significantly increased its targeted testing of cattle in high-risk
categories advocated by the OIE. This effort is directed at determining the
level of BSE in Canada, while monitoring the effectiveness of the suite of
risk-mitigating measures in place. Canada?s National BSE Surveillance
Program continues to demonstrate an extremely low level of BSE in Canada,
with 11 positive animals detected.

With respect to BSE, the safety of beef produced in Canada is assured by
public health measures enacted in 2003, following the first detection of BSE
in a native-born animal in Canada. The removal of specified risk material
(SRM)-those tissues that have been demonstrated to have the potential to
harbour BSE infectivity-from all animals slaughtered for human consumption
is the most effective single measure to protect consumers in Canada and
importing countries from exposure to BSE infectivity in meat products.

As demonstrated by the surveillance system, the feed ban implemented in 1997
is effectively preventing the amplification of BSE in Canada?s feed system.
Additional regulations to enhance Canada?s feed ban were enacted on July 12,
2007. The most important change is the removal of SRM from all animal feeds,
pet food and fertilizer. The enhancement will significantly accelerate
progress toward eradicating BSE from the national cattle herd by preventing
more than 99 per cent of potential BSE infectivity from entering the
Canadian feed system. These measures are effectively minimizing the risk of
transmitting BSE.

On May 22, 2007, Canada was officially categorized under the OIE?s
science-based system as a controlled BSE risk country. This status clearly
recognizes the effectiveness of Canada?s surveillance, mitigation and
eradication measures, and acknowledges the work done by all levels of
government, the cattle industry, veterinarians and ranchers to effectively
manage and eventually eradicate BSE in Canada.

Sunday, March 16, 2008

MAD COW DISEASE terminology UK c-BSE (typical), atypical BSE H or L, and or
Italian L-BASE


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