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From: TSS ()
Date: June 16, 2006 at 1:26 pm PST

OTTAWA, June 16, 2006 - The Canadian Food Inspection Agency has concluded its investigation of the case of bovine spongiform encephalopathy (BSE) confirmed on April 16, 2006, in a cow from British Columbia.

The investigation, conducted in line with international guidelines, identified 148 animals, including the affected animal’s herdmates and recent offspring. From this group, 22 live animals were located and all tested negative for BSE. One additional animal, which is currently pregnant, has been placed under quarantine and will be tested once it has calved. Of the remaining animals investigated, 77 had died or been slaughtered, 15 were exported to the United States and 33 were untraceable. Because BSE investigations typically involve older animals, it is common for a portion of the herdmates to go untraceable due to lack of records.

The Agency examined feed to which the affected animal would have been exposed early in its life, when cattle are most likely to develop BSE. Efforts to identify potential routes of transmission included reviews of records and procedures at the farm, retail and production levels. While a specific source of infection was not found, investigators determined that vehicles and equipment used to ship and receive a variety of ingredients likely contaminated cattle feed with the BSE agent.

Investigators also identified a feed ingredient supplier common to this case and Canada’s fourth BSE animal, confirmed on January 22, 2006. This potential link suggests that all of Canada’s BSE cases fall within the same geographic cluster, which is reflective of feed sourcing, production and distribution patterns. The clustering theory is explained in the epidemiological report Canada’s Assessment of the North American BSE Cases Diagnosed From 2003 to 2005, which is available on the Canadian Food Inspection Agency’s website.

The investigation noted high compliance with the requirements of Canada’s feed ban. Such findings—which have been observed during other investigations and regular inspections of feed mills, renderers and retailers across the country—confirm the presence of limited opportunities for contamination during feed manufacture, transportation, storage and use. With an eye to eliminating these risks, the Agency continues its progress toward enhancing Canada’s feed ban. Proposed changes would prohibit the use of potentially harmful cattle tissues as ingredients in any animal feeds.

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For more information:

Canadian Food Inspection Agency
Media Relations
(613) 228-6682

On April 8, 2006 a Holstein cow on a dairy farm in the Fraser Valley area of British Columbia was euthanized and sampled under Canada’s National BSE Surveillance Program. The carcass was placed under detention and held pending testing results. Brain samples from this animal were sent to a British Columbia provincial laboratory where they were screened for BSE using a Prionics rapid test. The sample produced an inconclusive reaction on April 11, 2006. In accordance with the prescribed testing protocol, the test was repeated on April 12 and produced a reaction a second time. Brain samples were then sent to the National BSE Reference Laboratory at the Canadian Science Centre for Human and Animal Health in Winnipeg where BSE was confirmed by the immunohistochemistry procedure on April 16, 2006. The carcass was secured from the sampling site and, after additional tissues were taken for research purposes, transferred to the Canadian Food Inspection Agency (CFIA) Lethbridge laboratory and subsequently incinerated. No part of the carcass entered the human food supply or animal feed chain.

The CFIA immediately initiated an epidemiological investigation along three lines of enquiry, based on the World Organization for Animal Health (OIE) BSE recommended guidelines, namely:

calves born to the affected cow during the two years prior to the onset of clinical signs;
the birth and feed cohort (cattle born on the farm of origin within the twelve months before and the twelve months after the birth of the affected animal or animals purchased and present on the farm during this period which were also in their first year of life); and
feed to which the animal may have been exposed early in its life.
Animal Investigation
The affected Holstein cow was born on April 29, 2000, and was 71 months, or circa six years old at the time of death. It had been moved from its farm of birth, to the index premises, just over one year prior to the onset of clinical signs of disease. The producer reported the duration of illness was approximately one month, during which the animal displayed progressive signs of impaired locomotion, culminating in the animal becoming non-ambulatory (downer). At that time a decision was made to euthanize the animal and, because it met the inclusion criteria of Canada’s National BSE Surveillance Program, arrangements were made to forward appropriate samples for laboratory evaluation.

The investigation revealed that the affected cow had two male calves born during the two years prior to the onset of clinical signs (born March 27, 2005 and April 7, 2004). CFIA investigators determined that the 2005 calf was either euthanized shortly after birth or entered the fattening/slaughter stream at a young age and subsequently died or was slaughtered. The 2004 calf was determined to have entered the fattening / slaughter stream and subsequently died or was slaughtered.

The birth farm was also a dairy operation. The feed cohort was determined to comprise 146 animals which, along with the affected animal, were raised on the birth farm. This cohort included Holstein females and males raised as breeding stock. Males sold at less than two weeks of age for fattening and subsequent slaughter without having access to any commercially prepared feeds were excluded from the investigation because they were not exposed to the same potentially contaminated feed as the index case. The trace-out investigation of the cohort located 23 live animals on the index premise and in other herds to which they had been sold. Twenty-two of these animals have been euthanized, sampled and tested negative for BSE. Disposal of the carcasses was by incineration. The remaining animal (under CFIA quarantine) is very near to calving, and for this reason its destruction and testing has been postponed. Because the cohort cattle would now be five to seven years of age, many had previously been slaughtered or died of causes unrelated to BSE. The following is the disposition of the remaining 123 animals in the cohort:

The index premises comprised a dairy herd and a cow-calf beef operation. The birth and feed cohort was determined to comprise 156 animals which, along with the affected animal, were born on the index premises in the dairy operation. The cohort included purebred Holsteins destined for the dairy herd or for sale and cross bred offspring removed to the beef herd at approximately one year of age or sold at an earlier age. The trace-out investigation of the birth and feed cohort located 38 live animals on the index premises and in other herds to which they had been sold. These animals were subsequently euthanized, sampled and tested negative for BSE. Because the birth cohort cattle would now be five to seven years of age, most had previously been slaughtered or died of natural causes. The disposition of the remaining 118 animals in the cohort was determined to be:

67 animals were traced and confirmed to have died or been slaughtered (one animal had previously been tested under Canada’s National BSE Surveillance Program with negative results);
8 animals were traced and presumed to have died or been slaughtered at other locations
15 were exported to the USA for breeding purposes (this information has been forwarded to US authorities for follow up)
33 animals were determined to be untraceable because of inadequate records
Feed Investigation
A thorough and detailed feed investigation was conducted at the birth farm to identify all of the feed materials used, the suppliers and sources of these products, and the feeding and feed storage management practices. Investigators focussed on all potential avenues of direct exposure to prohibited material, as well as potential areas of cross-contamination. Compliance with regulatory requirements of the feed ban was assessed throughout the investigation.

Investigation at the birth farm revealed it to be a dedicated dairy operation with no other livestock species present. All feed products to which the index animal had access were intended for feeding to ruminants and consisted of farm-grown or purchased forages (hay and silage) as well as commercially prepared feed. Pets on the farm (cats and one dog) were fed pet food that was stored and fed away from the dairy operation, thus eliminating these rations as a potential source of prohibited material to the BSE positive animal. Consistent with this farm’s practices, the index animal was housed in a series of indoor pens and did not have access to fertilizers, compost or other potential sources of prohibited material.

A review of feed storage and feeding practices identified the use of bagged, block and bulk commercially-prepared products. The only on-farm mixing equipment was a mixer wagon used to combine forages and commercially prepared lactation rations for the milking herd which was never shared or loaned off-farm.

All commercially prepared rations were purchased from a single supplier. Five products (representing the largest quantities the animal consumed) were manufactured by the supplier, in its own facility. A further six products (specialty products such as milk replacer and mineral/salt blocks) were manufactured in facilities owned by other companies.

Three of four facilities supplying specialty products (milk replacer, salt and mineral blocks) were dedicated free of all ingredients prohibited from use in ruminant feeds. The fourth facility (a supplier of mineral blocks to the birth farm) did handle prohibited material. Examination of the mixing records at this facility, for products to which the index animal may have been exposed, revealed improper sequencing between the manufacture of one lot of mineral blocks and a previous product that contained prohibited material. However, the nature of the product and the age of potential exposure (beginning at 6 months) make this an unlikely source of exposure of the affected animal as consumption would be extremely low.

The five major products manufactured in-house by the primary supplier, representing the largest quantities of feed the animal accessed (calf starter, calf grower, 2 different lactation rations and a dry cow ration), were formulated in a facility dedicated free of ingredients prohibited from use in ruminant feeds. The investigation confirmed the integrity of the procedures and equipment dedicated to all aspects of ingredient storage, processing, mixing, pelleting and feed storage, ruling out the possibility of cross-contamination occurring within the facility. However, the investigation also revealed that the facility shared an ingredient receiving system and bulk feed delivery trucks with another facility that did use prohibited materials in the manufacture of feeds for non-ruminant species. Under these circumstances, cross-contamination of feeds manufactured by the primary supplier could have occurred as a result of either the shared ingredient receiving system or during the delivery of bulk feed.

Interviews with staff at the latter facility identified that flushing procedures were used to prevent cross-contamination of ingredients and feeds at these points. However, written procedures in place at the time did not identify these requirements, and it was also not the practice at the time of production to document when flushing procedures were applied.

The risk of exposure of the index animal to a potentially contaminated feed cannot be ascribed to any specific product. In the absence of written records of procedures used to prevent cross-contamination, and lack of documentation to demonstrate these procedures were followed, it is not possible to verify actual production practices in place or to assess occurrence of possible failures. The effect of this is to identify all bagged feeds manufactured by this facility as representing a similar risk (due to shared ingredient receiving) and all bulk feeds as posing a similar risk (due to shared ingredient receiving and shared bulk delivery).

Identification of suppliers to the facility with shared ingredient receiving and bulk delivery trucks revealed five different sources of prohibited material. One of the major suppliers of prohibited material to this facility was the sole supplier to the facility servicing the birth farm of the BSE-affected cow diagnosed on January 23, 2006. These two most recent cases share the same susceptibility period as a result of their similar birth dates.

The findings of this investigation indicate that compliance with the1997 feed ban regulations was largely achieved through adoption of dedicated manufacturing facilities. Despite this, it is evident that opportunities for cross-contamination remained where conveyances and equipment were cross-utilized.

Investigation Overview
Given current knowledge about the epidemiology of BSE, it is reasonable to presume that this animal was exposed to feed containing a low level of infectivity during its first year of life. The investigation into the current case identified a number of possibilities but it was impossible to determine the exact source of exposure with a high degree of certainty. However, the findings suggest that the major rations could have become contaminated during manufacture or distribution.

For an analysis of the temporal and spatial distribution of BSE in North America, refer to Canada's Assessment of the North American BSE Cases Diagnosed From 2003 to 2005 - Part II published February 2006. It is available at:'eval2005/evale.shtml

The occurrence of this fifth case of BSE in Canada is consistent with the geographical and temporal clusters proposed therein.

The location of the index case’s birth farm may suggest yet an additional geographic cluster. However, given its possible relationship with a previously identified source of prohibited material, this occurrence similarly suggests that the feed distribution area associated with the existing geographic cluster may not be confined to Alberta, but may include additional Western provinces. The timing of the presumed exposure of Cases 4 and 5, born in the same year and month, suggests an insult to the feed system separate and apart from the one associated with the previous cases born in 1996 - 1997. Cases 4 and 5 suggest that the previously acknowledged and undetected first generation indigenous BSE cluster contained a minimum of two animals.

The detection of BSE affected animals born after the introduction of a feed ban is not unique to Canada, and does not signal failure of the measures in place to reduce and eventually eradicate BSE. Measures equivalent to Canada’s feed ban have been demonstrated to curtail the amplification and spread of BSE in cattle and be likely to eliminate the disease over time. Additional measures are currently being considered to further reduce the potential for contamination of ruminant feed, and hasten eradication.

The safety of meat currently being produced in Canada is assured by public health measures enacted in 2003, following the first detection of BSE in Canada. The removal of specified risk materials (SRM) from all animals slaughtered for human consumption in Canada is the most effective single measure to protect consumers in Canada and importing countries from exposure to BSE infectivity in meat products.

CFIA significantly increased the frequency of inspection of the animal feed system beginning in 2000. Since that time there has been an increasing level of compliance with the requirements of the feed ban.

Since the detection of BSE in Canada in May 2003, the increased testing of animals from the high risk categories (including this downer animal) was directed at determining the level of BSE in Canada, while monitoring the effectiveness of the suite of mitigating measures in place. It is reassuring that, among over 105,000 targeted tests conducted since 2003, this is only the fifth positive animal detected, indicating an extremely low level of BSE in Canada. Such detections demonstrate the integrity of Canada’s surveillance system, the level of awareness which exists at all levels of the animal and food production system and the commitment of Canadian producers and veterinarians to the elimination of this disease.

EFSA Scientific Report on the Assessment of the Geographical BSE-Risk (GBR) of Canada

Adopted July 2004 (Question N° EFSA-Q-2003-083)

[Last updated 08 September 2004]

Infected feed likely cause of Canada mad cow case
Fri Jun 16, 2006 7:43 PM BST

VANCOUVER, British Columbia (Reuters) - The investigation into Canada's most recent case of mad cow disease has found that contaminated feed was the likely source of the infection and might provide a link to an earlier case, officials said on Friday.

The Canadian Food Inspection Agency said the specific source of the infection, reported in April, was not found, but it said there was a feed ingredient supplier in common with a case of bovine spongiform encephalopathy that was discovered in a Canadian cow in January.

"This potential link suggests that all of Canada's BSE cases fall within the same geographic cluster, which is reflective of feed sourcing, production and distribution patterns," the inspection agency said in a press release.

The April case, Canada's fifth native-born BSE case, involved a nearly six-year-old pure-bred Holstein dairy cow in southwest British Columbia.

The January case involved a Holstein-Hereford dairy cow in Alberta. Alberta is a source of feed for the British Columbia livestock industry.

"While a specific source of infection was not found, investigators determined that vehicles and equipment used to ship and receive a variety of ingredients likely contaminated cattle feed with the BSE agent," the agency said in its final report on the investigation.

The investigation identified 148 herd mates and offspring of the diseased animal that was detected in April. Of this group, 22 live animals tested negative for BSE and 33 were untraceable. One live cow is pregnant and will be tested once it has calved.

Officials have said that no part of the infected animal entered the food chain.

Canada and the United States banned the inclusion of protein from cows and other ruminant animals such as goats and sheep in cattle feed in 1997, following Britain's mad cow outbreak. Scientists believe the ban helps stop the spread of the disease.

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