In the early 1990s BSE - bovine spongiform encephalopathy - ravaged the UK beef industry with 37,000 clinical cases of BSE and about 60,000 of the highest risk animals entering the food supply, compared with less than one a year today.
In late December 2003, for the first time the US identified a BSE infected cow in the state of Washington, leading to a ban from more than 20 countries on imports of US beef.
The European Food Safety Authority (EFSA) said on Friday that the risk assessment for US and Canada were both raised from 'unlikely' to 'likely but not confirmed or confirmed at a lower level.'
But the long-standing EU ban on growth-promoting hormones for cattle means it imports very little North American beef.
Norway's reclassification from 'highly unlikely' to 'unlikely but not excluded' means its exporters will have to remove a more of the 'significant risk material' before shipping beef into the EU.
BSE, a transmissible, neurodegenerative, fatal brain disease of cattle, has been linked to the human disease variant Creutzfeldt-Jakob disease (vCJD). According to the World Health Organisation (WHO), from October 1996 to November 2002, 129 cases of vCJD were reported in the UK, six in France and one each in Canada, Ireland, Italy and the US.
First identified in 1986, 180,000 cases of BSE have been diagnosed in the UK alone and only four out of the 25 EU member states have not yet declared any cases. BSE has affected the entire beef food chain, from producer to consumer. A recent report from the European Association of Animal Production has estimated the cost of BSE to EU15 (prior to accession) member states at more than €90 billion. In addition, the BSE crisis has had a significant impact on public trust in government and governmental scientific advice.