Animals > Animal Diseases > Bovine Spongiform Encephalopathy > Safeguards

Canada: a minimal BSE risk country

December 2003

With the recent detection of BSE in Canada (May 20, 2003)¹, Canada’s status has changed. In light of this event, there are a number of compelling reasons to conclude that the incidence of BSE in Canada is equivalent to that of a minimal risk country as defined by the OIE’s Terrestrial Animal Health Code² based on the primary criteria that there has been less than one in a million cases of BSE in each of the last four consecutive 12-month periods within the cattle population over 24 months of age. This statement provides an overview of the OIE criteria for BSE and a comparison with the BSE situation in Canada. Together with the extensive risk mitigation measures that have been implemented over the last two decades, Canada can justifiably be considered as a minimal risk country for BSE. Accordingly, the appropriate sanitary measures for Canadian animals and products of animal origin are those contained in the OIE Code for a minimal BSE risk country.

OIE Code criteria to determine the BSE status of a country

Each country interprets these criteria in the context of their animal health situation, domestic policies and programs for disease control; veterinary infrastructure; and environmental conditions. OIE recommendations can thus be applied with flexibility, to allow for each country’s individual circumstances and still provide for the achievement of health safeguards that are consistent with societal expectations, governmental goals and international obligations. International guidelines are dynamic and are modified from time to time in response to changes in the global disease situation and advances in scientific knowledge.

According to Article 2.3.13.2 of the OIE’s Terrestrial Animal Health Code² the BSE status of the cattle population of a country or zone can only be determined on the basis of the following criteria:

1)	the outcome of a risk assessment identifying all potential factors for BSE occurrence and their historic perspective, in particular:
		a)	the potential for introduction and recycling of the BSE agent through consumption by cattle of meat-and-bone meal or greaves of ruminant origin;
		b)	importation of meat-and-bone meal or greaves potentially contaminated with a transmissible spongiform encephalopathy (TSE) or feedstuffs containing either;
		c)	importation of animals or embryos/oocytes (other than cattle embryos described in Article 2.3.13.8.) potentially infected with a TSE;
		d)	epidemiological situation concerning all animal TSE in the country or zone;
		e)	extent of knowledge of the population structure of cattle, sheep and goats in the country or zone;
		f)	the origin and use of ruminant carcasses (including fallen stock), by-products and slaughterhouse waste, the parameters of the rendering processes and the methods of animal feed manufacture;
2)	on-going awareness programme for veterinarians, farmers, and workers involved in transportation, marketing and slaughter of cattle to encourage reporting of all cases of neurological disease in adult cattle;
3)	compulsory notification and investigation of all cattle showing clinical signs compatible with BSE;
4)	a BSE surveillance and monitoring system with emphasis on risks identified in point 1) above, taking into account the guidelines in Appendix 3.8.4.; records of the number and results of investigations should be maintained for at least 7 years;
5)	examination in an approved laboratory of brain or other tissues collected within the framework of the aforementioned surveillance system.

OIE Code criteria for a country with a minimal BSE risk

To enable countries to select those measures applicable to commodities such as cattle, meat and meat products that will protect human and animal life and health without imposing unjustified health barriers, the OIE Code² defines five categories of BSE risk ranging from free to provisionally free, minimal, moderate or high. While the OIE has provisions for recognizing a country as free or provisionally free, no countries have been assessed to date. As a result discussions on BSE status are undertaken on a bilateral basis between trading partners.

Article 2.3.13.5 of the OIE Codea² outlines the requirements for the cattle population of a country to be considered as presenting a minimal BSE risk. The country should comply with the following requirements:

1)	a risk assessment, as described in point 1) of Article 2.3.13.2., has been conducted and it has been demonstrated that appropriate measures have been taken for the relevant period of time to manage any risk identified;
2)	EITHER:
		a)	the last indigenous case of BSE was reported more than 7 years ago, the criteria in points 2) to 5) of Article 2.3.13.2. are complied with and the ban on feeding ruminants with meat-and-bone meal and greaves derived from ruminants is effectively enforced, but:
			i)	the criteria in points 2) to 5) of Article 2.3.13.2. have not been complied with for 7 years; or
			ii)	the ban on feeding ruminants with meat-and-bone meal and greaves derived from ruminants has not been effectively enforced for 8 years;
	OR
		b)	the last indigenous case of BSE has been reported less than 7 years ago, and the BSE incidence rate, calculated on the basis of indigenous cases, has been less than one case per million during each of the last four consecutive 12-month periods within the cattle population over 24 months of age in the country or zone (Note: For countries with a population of less than one million adult cattle, the maximum allowed incidence should be expressed in cattle-years.), and:
			i)	the ban on feeding ruminants with meat-and-bone meal and greaves derived from ruminants has been effectively enforced for at least 8 years;
			ii)	the criteria in points 2) to 5) of Article 2.3.13.2. have been complied with for at least 7 years;
			iii)	the affected cattle as well as: if these are females, all their progeny born within 2 years prior to, and after, clinical onset of the disease, if alive in the country or zone, when slaughtered or at death, are completely destroyed, and all cattle which, during their first year of life, were reared with the affected cattle during their first year of life, and, which investigation showed consumed the same potentially contaminated feed during that period, or where the results of an investigation are inconclusive, all cattle born in the same herd as, and within 12 months of the birth of, the affected cattle if alive in the country or zone, when slaughtered or at death, are completely destroyed.

Evidence supporting Canada as a country with minimal BSE risk

In order for the cattle population of Canada to be considered as presenting a minimal BSE risk Article 2.3.13.5 of the OIE Code² requires that:

a risk assessment as described in point 1) of Article 2.3.13.2., has been conducted and it has been demonstrated that appropriate measures have been taken for the relevant period of time to manage any risk identified;

In 2002 Canada completed a BSE Risk Assessment³,⁴ which concluded that the likelihood of BSE being introduced into the animal feed chain as a result of importing cattle from the UK or Europe from 1979 to 1993 and spreading to at least one other bovine animal prior to the introduction of the feed ban in 1997 was 7.3 x 10^–3, which was considered to be negligible. Although BSE has now been detected in Canada, confirming that at least one animal became infected, the model’s results nevertheless indicate that only one or a few animals could have become infected.

The findings of the Canadian Risk Assessment are consistent with the European Commission’s Assessment of the Geographical BSE-Risk (GBR) of Canada⁵ undertaken in 2000. It concluded that "it is unlikely but cannot be excluded that domestic cattle are (clinically or pre-clinically) infected with the BSE-agent". In reaching its decision the Commission noted that "the Canadian system was exposed to a very low or low challenge by cattle imports from the UK " and "it cannot be excluded that BSE-infectivity entered the country by this route". Furthermore, the Commission went on to state that while "a low-level domestic prevalence cannot therefore be fully excluded to exist since the early 90s ... the level must be below the detection level of the rather good passive surveillance in place."

In the Canadian Risk Assessment all the criteria specified point 1) of Article 2.3.13.2 were addressed:

the potential for introduction and recycling of the BSE agent through consumption by cattle of meat-and-bone meal (MBM) or greaves of ruminant origin

A mammalian to ruminant feed ban (with the exception of pure porcine and equine meal; and milk, blood, gelatin and rendered animal fat from all species) was introduced in 1997³. Prior to this rendering and feeding practices would have allowed BSE to cycle through cattle.
Compliance with the feed ban has been high as verified by routine inspections of both renderers and feed mills³ so it is extremely unlikely that animals would have been exposed to the BSE agent after the feed ban.
The feed ban would have resulted in a dramatic reduction in exposure, effectively eliminating further spread and amplification of the BSE agent. Given the impact of the feed ban and the incubation period of BSE, the number of BSE cases would be expected to peak six years later, that is 2003.
The potential number of BSE cases remaining in the cattle population in 2003 would be extremely small as only a few animals are likely to have become infected prior to the feed ban and the majority of these would have already been culled, slaughtered or died.

ii)

importation of MBM or greaves potentially contaminated with TSE or feedstuffs containing either

MBM or greaves for livestock feed have not been imported from the United Kingdom or any other countries subsequently affected by BSE since 1978. All MBM imported for livestock feed has come from Australia, New Zealand or the United States of America (USA)³. It is important to note that both Australia and New Zealand were assessed by the European Commission’s Assessment of the Geographical BSE-Risk as GBR level 1 (presence of BSE highly unlikely) ^6

7 and the USA as a GBR level II (presence of BSE unlikely but not excluded)⁸. In addition, the United States Department of Agriculture’s own BSE risk assessment⁹ concluded that there was only a small chance that BSE was introduced and spread to cattle and that, even if it were, the course of the disease has been arrested and destined for eradication by the measures currently in place. BSE has not been reported in any of these countries¹⁰.

iii)

importation of animals or embryos/oocytes potentially infected with a TSE

Historically, the vast majority of cattle imported into Canada originated from countries where BSE has not been reported:
	Most of these cattle came from the USA¹ which has not reported BSE to date¹⁰. The GBR level II (presence of BSE unlikely but not excluded) rating⁸assigned to the USA by the European Commission is supported by the United States Department of Agriculture’s own BSE risk assessment⁹ , which concluded that there was only a small chance that BSE was introduced and spread to cattle and that, even if it were, the course of the disease has been arrested and destined for eradication by the measures currently in place. Small numbers of breeding cattle have been imported into Canada from New Zealand and Australia^5, ¹¹, both of which, as noted already, have not reported BSE to date¹⁰ and have been assessed by the European Commission as GBR level 1 (presence of BSE highly unlikely)^6, 7.
While small numbers of cattle have been imported from several countries affected by BSE, considering that:
	Canada has not imported cattle from the UK since 1990. From 1994 an import ban was imposed on all countries where BSE had been detected in native cattle. From 1996 live cattle could only be imported from countries that Canada designated as free from BSE following a comprehensive risk assessment³ Although 182 cattle were imported from the United Kingdom between 1982 and 1990, tissues from only 68 of these animals were potentially rendered after they were slaughtered (59) or died (9) and entered the animal feed system prior to 1993³. Only 11 of these 68 animals were imported in 1988 to 1989, the period of greatest risk identified by the European Commission’s Assessment of the Geographical BSE-Risk of Canada⁵. This report concluded that the challenge posed by these animals was low and for that the challenge associated with animals imported prior to 1988 was very low. From 1990 a ban was placed on further cattle imports from the UK and all remaining cattle were placed under surveillance. Following the detection of BSE in one of these imported animals in 1993 all other animals were slaughtered and incinerated³. Although 405 cattle were imported from several mainland European countries between 1979 and 1985 that subsequently reported cases of BSE, the information in Canada’s Risk Assessment³ concerning the year in which animals were imported and the number of animals imported, together with the updated GBR opinion of 2002⁹ , indicates that likelihood of BSE being introduced into Canada from these animals was negligible. Of nine cattle imported from Denmark in 1993 inedible tissues from seven of these animals may have been potentially rendered³. However, the updated GBR opinion of 2002¹² indicates that likelihood of BSE being introduced into Canada from these animals was negligible. Nineteen water buffalo were imported from Denmark in 2000. One animal died in quarantine from non-BSE related causes and was incinerated. Following the detection of BSE in Denmark that same year all remaining animals were destroyed³. Twenty-two animals were imported from Japan in the 1990’s before BSE was detected in that country. Four were re-exported to the USA. Inedible tissue from four of the remaining eighteen animals may have been rendered after they were culled due to reproductive failure. It is important to note that these animals were culled after the feed ban was introduced in 1997. All fourteen remaining animals were destroyed³.
The most likely source of BSE for Canada is associated with a limited number of live cattle imported from the UK in the 1980s that may have subsequently entered the animal feed chain. From 1990 a ban was placed on further cattle imports from the UK . Only one or a few of these animals would have been potentially infected with BSE and introduced infectivity into the animal feed chain in the 1980s after they were slaughtered or died. Although the rendering and feeding practices at that time would have allowed BSE to cycle through cattle, considering the prolonged incubation period of BSE (average of 6 years), the amplification and spread of BSE would have been extremely slow reaching a peak in 1996-97, just prior to the introduction of the feed ban in 1997.

iv)

epidemiological situation concerning all animal TSE in Canada

Both Scrapie, affecting sheep and goats, and Chronic Wasting Disease, affecting deer and elk, occur in Canada. They are both reportable diseases. The epidemiological situation and control programmes are extensively described in appendices of the Canadian BSE Risk Assessment³, by Kellar and Lees¹¹ and on the Government of Canada Web site^{13, 14}.

extent of knowledge of the population structure of cattle, sheep and goats in Canada

The Government of Canada has an excellent understanding of the population structure of cattle, sheep and goats. This information is extensively described in the Canadian BSE Risk Assessment³

vi)

the origin and use of ruminant carcasses (including fallen stock), by-products and slaughterhouse waste, the parameters of the rendering processes and the method of animals feed manufacture

These factors are all extensively described in the Canadian BSE Risk Assessment³.

EITHER:

the last indigenous case of BSE was reported more than 7 years ago …… (Not applicable as the indigenous case was reported in 2003)

the last indigenous case of BSE has been reported less than 7 years ago, and the BSE incidence rate, calculated on the basis of indigenous cases, has been less than one case per million during each of the last four consecutive 12-month periods within the cattle population over 24 months of age in Canada, and:

There are approximately 5.5 million cattle in this age class in Canada³. Considering that a surveillance program for BSE was introduced in 1992, that OIE surveillance targets have been achieved since 1996³ and that only one case of BSE has been detected in the last 12-month period, the incidence of BSE cases in Canada remains below one in a million.

the ban on feeding ruminants with meat-and-bone meal and greaves derived from ruminants has been effectively enforced for at least 8 years;

Following the introduction of an effectively enforced feed ban in which exposure to BSE is eliminated, it can be expected that the number of BSE cases remaining in the cattle population after 8 years would be extremely low. Although it has only been six years since the introduction of a feed ban in 1997, an equivalent level of assurance to that provided by the eight year period stipulated in the OIE Code can be provided by considering that:
	Canada introduced a surveillance for program for BSE in 1992 and OIE surveillance targets have been achieved for each of the last seven years³. Meat and bone meal (MBM) for livestock feed has not been imported from the United Kingdom or any other countries subsequently affected by BSE since 1978³. The most likely source of BSE would have been cattle imported from the UK in the 1980s. Only one or a few of these animals would have been potentially infected with BSE and introduced infectivity into the animal feed chain in the 1980s after they were slaughtered or died³. Although the rendering and feeding practices at that time would have allowed BSE to cycle through cattle, considering the prolonged incubation period of BSE, the amplification and spread of BSE would have been extremely slow reaching a peak in 1996-97, just prior to the introduction of a feed ban in 1997. The feed ban would have resulted in a dramatic reduction in exposure, effectively eliminating further spread and amplification of BSE. Given the impact of the feed ban and the incubation period of BSE, the number of BSE cases would be expected to peak approximately six years later, that is 2003. Compliance with the Canadian feed ban has been high as verified by routine inspections of both renderers and feed mills³ so it is extremely unlikely that animals would have been exposed to BSE infectivity after the feed ban.
As a result the potential number of BSE cases remaining in the cattle population in 2003 would be extremely small as only a few animals are likely to have become infected prior to the feed ban and the majority of these would have already been culled, slaughtered or died.

ii)

the criteria in points 2) to 5) of Article 2.3.13.2. have been complied with for at least 7 years;

An ongoing education and awareness program targeting veterinarians, producers and workers in the cattle industry has been in place since 1989³,¹¹.
Compulsory notification and investigation of all cattle showing clinical signs compatible with BSE has been in place since 1990³, 11.
Following the introduction of a surveillance program for BSE in 1992, Canada has met or exceeded OIE surveillance targets aimed at determining whether BSE is present in a country for each of the last seven years³. The incidence targeted by the OIE in setting this standard is one in a million amongst cattle older than 24 months of age.
All samples collected as part of the surveillance program are examined in a Government of Canada approved laboratory. The tests and standards employed conform with the OIE’s Manual of Standards for Diagnostic Tests and Vaccines¹⁵.

iii)

the affected cattle as well as:

if these are females, all their progeny born within 2 years prior to, and after, clinical onset of the disease, if alive in the country or zone, when slaughtered or at death, are completely destroyed, and
- The BSE case detected in Canada on 20 May 2003 was a six year old cow born in March 1997. It had two calves born within the 2 year period prior to the diagnosis of BSE. Both were male calves, one born in 2001 and subsequently slaughtered as a steer in 2002 while the other, born in 2002, was destroyed and tested as part of the investigation in 2003. The test result was negative ¹.
all cattle which, during their first year of life, were reared with the affected cattle during their first year of life, and, which investigation showed consumed the same potentially contaminated feed during that period, or
- Ninety-two calves were born in the calf crop of spring 1997 and reared in their first year of life with the BSE case. A calf starter ration, produced and purchased in advance of the ruminant feed ban, containing MBM was fed to these calves. At the time of the diagnosis of the BSE case in May 2003, 38 of these animals were still alive (35 cows and 3 bulls). All of these animals were destroyed and tested for BSE as part of the investigation. All test results were negative ¹.
where the results of an investigation are inconclusive, all cattle born in the same herd as, and within 12 months of the birth of, the affected cattle
- The results of the investigation were conclusive.

if alive in the country or zone, when slaughtered or at death, are completely destroyed.

Policy response

A team of internationally recognized BSE experts¹⁶ was invited to review Canada’s response to the detection BSE in an indigenous cow. The team acknowledged the comprehensive scope, thoroughness and transparency of the response and the competence, capacity and dedication of the Canadian Veterinary Administration. They also acknowledged that the measures already in place in Canada had achieved their designed outcome as the BSE case was identified and did not enter the human food chain. The team considered that the cow would have most likely been exposed to BSE through the consumption of contaminated MBM early in its life. They also considered that, while it is possible that other cattle may also have been similarly exposed to BSE, the various measures, including the feed ban, would have reduced the spread and amplification of BSE. The team recommended that a number of measures be adopted to enhance Canada’s approach to BSE:

1)	A prohibition on Specified Risk Materials (SRMs) from the human food and animal feed chain.
2)	The exclusion of raw materials containing potentially infectious tissues from Advanced Meat Recovery/Mechanically Recovered Meat processes.
3)	An increase in the number of animals tested in the existing surveillance program to obtain a more accurate picture of BSE.

Following the recommendations of the international team, the Government of Canada:

1)	Implemented an SRM ban, effective from 24 July 2003^{17, 19} SRMs are defined in regulations under both the Food and Drug Act¹⁷ and Health of Animals Act¹⁸ as skull, brain, trigeminal ganglia, eyes, tonsils, spinal cord and dorsal root ganglia of cattle aged 30 months or older, and the distal ileum of cattle of all ages. This list of SRMs actually exceeds the OIE Code recommendations for a minimal BSE risk country as it also classifies tonsils, trigeminal ganglia and the distal ileum as SRMs. Until such time as suitable techniques are developed to ensure that the dorsal root ganglia can be entirely removed from the vertebral column, the Government of Canada’s Meat Hygiene Directive¹⁹ issued under the Meat Inspection Regulations, mandates that the vertebral column from all cattle aged 30 months or older must be removed and disposed of as inedible product. The directive also stipulates that the vertebral column of these cattle cannot be used in the preparation of mechanically separated meat or finely textured meat. In addition, to ensure the complete removal of the distal ileum, the entire small intestine of all cattle regardless of their age must be removed and disposed of as inedible product.
2)	Initiated a review of the existing mammalian to ruminant (with exceptions) feed ban to determine if even more stringent measures are required.
3)	Initiated a review of the number of animals tested in the existing BSE surveillance program which already focuses on highest risk populations of adult cattle referred to by the international team: adult risk cattle demonstrating clinical signs compatible with BSE (neurological cases) animals found dead (dead stock) animals that are non-ambulatory (downers) animals presented for emergency slaughter (dying) animals sent to normal slaughter and are found to be sick at ante mortem inspection (diseased)
4)	Initiated a review of current import policies.

Conclusions

In conclusion, although BSE has recently been detected in an indigenous cow, Canada’s stringent approach to BSE over the last two decades and the results of the BSE surveillance program to date provide compelling evidence that the incidence of BSE in Canada is equivalent to that of a minimal risk country as defined in the OIE Code. Accordingly, the appropriate sanitary measures for Canadian animals and products of animal origin are those contained in the OIE Code for a minimal BSE risk country.

References

Revised: December 2003