The international framework for the evaluation of the BSE risk of countries has continuously evolved over the past several years in response to advancements in the understanding of the disease and the demonstrated effectiveness of measures over time.

Initially, in the absence of an agreed international standard and assessment criteria, BSE risk assessments varied by country and were conducted through bilateral and multilateral arrangements. These ranged from the European Union’s Geographic Based Risk (commonly referred to as the GBR), to the harmonized questionnaire and shared assessment undertaken by Canada, the United States and Mexico (NAFTA Protocol), to the Australian-New Zealand Food Safety Assessment.

In 1999, the World Organization for Animal Health (referred to by its historical acronym, the OIE), recognized by the World Trade Organization as the international standard setting body for animal health and diseases, developed a five level system that would categorize BSE risk in countries as free, provisionally free, minimum, moderate and high risk.

In 2003, due to advancements in the International Terrestrial Animal Health Code and improved surveillance standards the OIE began developing a revised, simplified categorization system which was more reflective of the science of the day.

Under the previous five level system of categorization, one of the determining factors for categorization of a country had been the number of cases detected within a twelve month period. However it was demonstrated not to be a scientifically sound indicator of a country's true BSE status. For example, the detection of ten cases in a twelve month period where the animals found were all nine years of age or older is not indicative of the BSE status of the country at present but rather is reflective of events some nine to ten years previous due to the long incubation period of the disease.

Furthermore the system, as it was, did not objectively take into account the evolving science with respect to the impact on incubation of the age of animal at exposure or the level of exposure to BSE, nor did the system adequately recognize and reward investments countries had made to effectively mitigate the further spread of the disease.

In May 2005, during the 73^rd General Session of the International Committee of the OIE, the member countries formally adopted a simplified 3 tiered categorization system for evaluating the BSE risk.

The revised categorization system was designed to reflect the current knowledge and understanding of BSE and to demonstrate the effectiveness of investments countries have made to mitigate the spread and eventually eradicate the disease. The categories are: Negligible, Controlled and Undetermined risk.

In applications for BSE risk assessment, countries must demonstrate compliance with the following recommended safeguards: BSE surveillance has been conducted in accordance with the OIE’s BSE guidelines; an appropriate feed ban is in place; awareness, education and reporting programs exist; diagnostic competency is demonstrated and a risk assessment has been undertaken to guide the design of policies to protect animal and human health.

Under the OIE criteria, a country can be categorized as negligible risk if it can demonstrate compliance with the recommended safeguards and it has either never had a case of BSE in a domestic animal or any infected domestic animals were born more than 11 years ago. Canada was categorized as a controlled risk country because, while it has demonstrated compliance with the recommended safeguards, it has had BSE cases in domestic animals born in the previous 11 years. Countries which are not able to demonstrate they meet, or have not been assessed against, the requirements for negligible risk or controlled risk are placed in the undetermined category.

To determine a country’s BSE risk, country submissions and supporting evidence are reviewed by a team of international subject matter experts. Based on their evaluation, a recommendation is made to the Scientific Commission for Animal Diseases. The Commission reviews the recommendation and, if accepted and endorsed, a proposal is made for the country as either a Negligible or Controlled BSE risk. The proposal is then circulated to the Delegates of all OIE member countries. Member countries then have sixty days in which to register an objection in writing with supporting scientific or technical grounds. Official recognition is achieved through adoption of a resolution by the International Committee during the General Session comment.

Countries which have been assessed as negligible or controlled risk must also notify the OIE in writing during the month of November of each year that the epidemiological situation in respect of BSE has remained unchanged and document their the continued observance of OIE standards. Failure to comply provides grounds for the OIE to revoke the given status.