What is Bovine Spongiform Encephalopathy (BSE)?
Bovine Spongiform Encephalopathy, or BSE, is a progressive, fatal disease of the nervous system of cattle. It is one member of a family of diseases known as transmissible spongiform encephalopathies (TSEs). Other TSEs include scrapie in sheep, Chronic Wasting Disease (CWD) in deer and elk, and Creutzfeldt-Jakob Disease (CJD) in humans.
What causes BSE?
Although the exact cause of BSE is unknown, it is associated with the accumulation of abnormal proteins, or BSE prions, in the brain. There is no treatment or vaccine currently available for the disease.
What are the symptoms of BSE?
Cattle with BSE may not show any signs of the disease for up to three to six years after they have been exposed to BSE prions. Symptoms are variable but always progressive and may include, nervous or aggressive behavior, abnormal posture, incoordination, difficulty standing, decreased milk production, and weight loss. These symptoms may progress for up to six months until the animal dies.
How is BSE transmitted?
BSE is not a contagious disease. Research indicates that the only risk factor for the spread of BSE is through feeding cattle meat and bone meal (MBM) derived from BSE-infected cattle. BSE prions are resistant to normal inactivation procedures, such as disinfectants and heat. BSE prions are not completely destroyed by the rendering process.
BSE is not contagious and cannot be transmitted animal-to-animal contact. Nor are BSE prions present in milk or dairy products.
How is BSE diagnosed?
BSE is a federally reportable disease in Canada, under the authority of the Health of Animals Act. Suspected cases of BSE must be reported to the Canadian Food Inspection Agency (CFIA).
There is no test to diagnose BSE in live animals. The disease can only be confirmed by testing the animal's brain after death. Immunohistochemistry (IHC) is the international gold standard for confirmatory testing. This procedure takes up to five days before results are available. The CFIA has approved a number of rapid tests for BSE, which decrease the testing time by half. Alberta Agriculture, Food and Rural Development (AAFRD) has chosen to use the Bio-Rad TeSeE ELISA kit as a rapid screening test for BSE. This test is being conducted in an enhanced Biosecurity Level II facility. All tests producing a reaction will be confirmed by IHC at CFIA's National Centre for Foreign Animal Disease (NCFAD) in Winnipeg.
Do we have BSE in Canada?
BSE has been diagnosed in Canada five times. The first case, in 1993, was found in a purebred beef cow imported from Great Britain in 1987. The second case was detected in May 2003 in a beef cow from northern Alberta. This animal was condemned at slaughter and tested for BSE as part of Alberta's BSE surveillance program. The CFIA conducted an extensive investigation and depopulated over 2,700 head of cattle. Approximately 2000 animals were tested for BSE and all were negative. The CFIA investigation was able to pinpoint the farm of origin and found evidence that the index cow may have been exposed to MBM very early in its life.
Two cases of BSE were confirmed in January 2005, one in an eight-year old Holstein cow from north central Alberta and another in an approximately seven-year old beef cow from central Alberta. No part of either animal entered the human food or animal feed system. Both of these animals were sampled by veterinarians and submitted for testing under the Canada-Alberta BSE Surveillance Program (CABSESP). CFIA conducted extensive investigations into each animal's history, including the feed they may have been exposed to during their lives. CFIA concluded that both animals were most likely exposed to low levels of BSE infectivity through consumption of feed containing ruminant meat and bone meal during their first years of life. All animals tested as part of CFIA's traceout investigations were negative.
In January 2006, BSE was detected in a six-year old crossbred cow in north central Alberta. The animal was sampled and tested under the CABSESP. No part of the animal entered the food or feed system. CFIA located and tested 91 animals from the infected animal's birth cohort (those born within 12 months of the infected animal), as well as one calf born in 2005. All animals have tested negative. CFIA's feed investigation is ongoing.
A dairy cow diagnosed with BSE in the United States in December 2003 originated from a farm in Alberta. It was born prior to the implementation of the ruminant-to-ruminant feed ban in August 1997. The CFIA investigation determined that this animal had also been exposed to MBM early in its life. The CFIA depopulated 12 birth cohorts and all tested negative for BSE.
What are the trade implications of BSE?
The Office International des Epizooties (OIE), the world animal health organization, has developed criteria to classify each country, based upon their risk for BSE. Canada is classified as a "controlled" risk for BSE. The OIE BSE Code provides guidelines for other countries to use in determining their import policies.
As a result of the first Canadian-born case of BSE reported in May 2003, over 30 countries, including the United States (US), placed trading restrictions on beef exports from Canada. In August 2003, the US began allowing whole-muscle cuts from Canadian cattle less than 30 months of age into their country. On July 13, 2005, the US border opened to Canadian ruminants under 30 months of age. The cost of BSE to the Canadian cattle industry is estimated to be $7 billion.
What other countries have BSE?
Other countries known to have native cases of BSE include, the United Kingdom, Germany, France, Portugal, Denmark, Spain, Italy, Switzerland, the Netherlands, Finland, Greece, Belgium, Austria, Czech Republic, Ireland, Israel, Liechtenstein, Slovakia, Slovenia, Luxembourg and Japan.
What is being done to prevent BSE from becoming established in Canada?
Canada has implemented a number of precautions to prevent the spread of BSE and to protect public health. These measures include the following:
- In 1990, Canada made BSE a reportable disease. Any suspect cases of BSE must be reported to the CFIA, who is responsible for control and eradication of the disease, under the authority of the Health of Animals Act.
- Canada only allows importation of live ruminants, their meat and meat products from countries that Canada considers to be free of BSE. Additional controls have also been placed on animal products and by-products from countries that have confirmed BSE in native animals.
- Canada has not imported European ruminant-derived MBM for use in livestock feeds for more than a decade. In December 2000, Canada banned the import of rendered animal material from any species from any country that Canada does not recognize as free of BSE.
- In August 1997, Canada introduced a ruminant-to-ruminant feed ban, meaning that rendered protein products from ruminant animals (cattle, sheep, goats, bison, elk or deer) cannot be fed to other ruminants.
- In July 2003, Canada implemented the removal of specified risk material (SRM) from the human food chain. SRMs are tissues that, in BSE-infected cattle, contain more than 99% of BSE infectivity, and include brain, spinal cord, trigeminal and dorsal root ganglia, eyes, tonsils in animals over 30 months of age and the intestine in cattle of all ages. Alberta immediately implemented this SRM ban at all provincially licensed abattoirs and meat processing facilities in July 2003.
- In December 2004, the CFIA announced amendments to certain federal regulations regarding the prohibition of SRMs from being used in all animal feed, including pet food and fertilizers. These changes are still under consideration.
- The implementation of the Canadian Cattle Identification Program (CCIP) makes it possible to trace individual animal movements from the herd of origin to slaughter. In 2004, the program was expanded to include bison and sheep.
Canada is continually assessing international scientific information as it becomes available and modifying policies, as required.
What is the purpose of testing cattle for BSE?
There are two primary reasons why Canada must conduct surveillance for BSE. First, BSE surveillance is a measure of the effectiveness of the precautionary processes Canada has implemented since 1990 to prevent the spread of BSE if it existed in our cattle herd. For example, the ruminant-to-ruminant feed ban implemented in 1997.
BSE surveillance also facilitates an estimate the prevalence of BSE in Canada's adult cattle herd. This is important because it allows Canada to improve or maintain its status with the OIE and the international community. If Canada's BSE status becomes undetermined, it will be impossible to ever regain market access for cattle and beef products.
Canada has conducted surveillance for BSE since 1993. Alberta Agriculture, Food and Rural Development (AAFRD) has participated in the national BSE surveillance program since 1996. Alberta enhanced its BSE surveillance in 2002 by targeting cattle over 18 months of age that exhibited neurological signs, were downers or were condemned at a provincially licensed abattoir, were presented for emergency slaughter or died for no apparent reason. AAFRD submits a report every month to the CFIA. Alberta and Canada have consistently tested more animals than recommended by the OIE.
In 2004, the CFIA announced enhanced targets for BSE testing----8,000 cattle in 2004, increasing to 30,000 annually. Based upon Alberta's proportion of Canada's adult cattle population, nearly 40%, approximately 2,700 BSE tests must be performed on cattle originating in Alberta in 2004 and over 10,000 in 2005 and beyond.
In September 2004, the CFIA and AAFRD jointly announced the Canada-Alberta BSE Surveillance Program to increase submissions of high-risk cattle for BSE testing.
What is the Canada-Alberta BSE Surveillance Program?
The Canada-Alberta BSE Surveillance Program provides reimbursement to producers, veterinarians and provincial abattoirs for the costs associated with submitting testable samples from eligible cattle for BSE testing. AAFRD tops-up the $75 CFIA reimbursement to producers by $150, issuing producers a single cheque for $225. Veterinarians are reimbursed for all expenses associated with obtaining specimens on farm and shipping them to either the AAFRD laboratory in Edmonton or the CFIA laboratory in Lethbridge. AAFRD is issuing the funds in a single cheque, with the first $100 recovered from CFIA. Provincial abattoirs will be reimbursed $75 per testable sample to offset the expenses associated with holding the carcass and offal. Samples are harvested by provincial meat inspectors and submitted for testing.
Which cattle are eligible under the Program?
Eligible cattle include those which fall into one of the following categories (the 4Ds): 1) downers, 2) dead, 3) diseased or 4) distressed. Cattle eligibility must be determined by a veterinarian or a CFIA inspector. If a producer suspects he/she has a qualifying animal, they should contact their veterinarian or CFIA at 1-866-400-4244.
How many Alberta cattle have been tested under the Program?
Please go to the BSE Weekly and Cumulative Surveillance Results web page for up-to-date information.
Why don't we test all cattle for BSE?
OIE guidelines are based on science and recommend BSE surveillance be targeted to those groups of cattle most likely to test positive. It takes between two and eight years following exposure to BSE before cattle develop clinical disease. In the United Kingdom, of 180,000 cattle found to be positive for BSE, only 0.05% were 30 months of age or less and 0.006% were 24 months of age or less. Over 80% of cattle slaughtered in Alberta are less than 18 to 22 months of age and are, therefore, extremely unlikely to test positive. Public health is not protected by BSE surveillance; rather it is protected by the removal of SRMs from the human food chain.
Is Alberta's beef safe?
Yes, Alberta beef and dairy products are safe for consumption. Alberta's food safety system is among the best in the world. Detection of our BSE cases is proof of the effectiveness of our surveillance and monitoring systems. SRM removal eliminates more than 99% of the BSE infectivity in infected cattle. As well, infectivity has never been detected in skeletal muscles tissues, from which most quality meat is derived. BSE prions are concentrated in nervous tissues such as the brain, and spinal cord of affected cattle.
What are the responsibilities of beef and dairy producers?
- Anyone suspecting that an animal may have BSE should contact his or her veterinarian to diagnose the condition. Cattle suspected of having BSE must be reported to the CFIA, by law.
- Producers who believe they have an animal that is eligible under the Canada-Alberta BSE Surveillance Program should contact their local veterinarian or the CFIA at 1-866-400-4244. Failure by Canada to test an adequate number of these cattle may jeopardize market access of ruminant or ruminant products.
- Producers are responsible for checking feedbags carefully for the label Do not feed to cattle, sheep, deer or other ruminants. Such feed contains material that is prohibited for ruminants. If you mix feed on your farm, ensure that you follow directions and prevent cross contamination of ruminant feeds with that intended for non-ruminants (horses, hogs, poultry).
- All invoices for feed purchased must be kept for at least two years.
- When there is a confirmed case of a disease such as BSE, accurate records become vital for tracing animal movements, animal contacts and finding the herd of origin, offspring, past herd mates and any connection to other herds. The sooner these animals are identified, the sooner the investigation can be completed. The seriousness of one case of BSE is evident. Accurate records are essential to minimize the impact of detecting a case of BSE.
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