AN expert on BSE has said it is still not clear if the disease can be eradicated by 2001, as a recent epidemiological survey from Oxford University suggested.
Speaking to journalists at a Commission briefing yesterday to outline its BSE research priorities, Prof Charles Weissman, of Zurich University, who heads a specialist EU committee on the issue, said there were still major gaps in the understanding of the disease and its transmission.
He cited the unexplained persistence of scrapie in sheep over hundreds of years to warns against over optimistic suggestions that BSE could be completely eliminated.
Prof Weissman said he was not convinced that some of the scientific premises of the Oxford study were valid. The study has been used by the British government to call into question the need for a selective cull of some 120,000 at risk animals.
Among the research priorities, he said, was the investigation of the possibility that many cattle may have the disease causing agent, prions, in their brains, without ever developing BSE.
Such a possibility would clearly affect the scale and approach of an eradication programme.
Although the transmission to humans of BSE was not completely proven, he was convinced of the fact, and the research programmes would be based on the probability that it does cross the species barrier. There would be an attempt to quantify the risk of transmission and to test if this could occur through repeated exposure to very small doses.
The ease of oral transmission would be tested in experiments on monkeys whose PRP gene sequences most closely matches the human version of the gene which is attacked by the prions.
It is still not dear, he said, if what appears to be "vertical" transmission from mother to calf occurs because of prions passing through the placenta or is simply the result of a statistical distortion due to the passing on of a higher genetic predisposition to the disease.
The Commission will also back research into the possibilities of transmission through feeding to other animals, although preliminary studies on pigs and chicken suggest this is not possible.
The Agriculture Commissioner, Mr Franz Fischler, welcomed the recommendations on research prioritisation.
