THE human cost of the mad cow disease epidemic in the UK a decade ago remains uncertain. At one time it was feared millions might be at risk after eating beef from cattle with the disease, but so far fewer than 200 people have developed vCJD, the human form of BSE. Now tests on 13,000 preserved tonsil samples suggest the toll could rise to around 4000.
But the estimate is little more than a guess, based on just three samples that tested positive for the prion protein that causes vCJD. Of the three positives, two were doubtful. And even if people鈥檚 tonsils contain prions, they might not necessarily develop vCJD.
鈥淚 don鈥檛 think too much should be read into our findings, but they should be investigated further,鈥� says David Hilton of the Derriford Hospital in Plymouth, who led the study (Journal of Pathology, DOI: 10.1002/path.1580)
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A government agency already plans to test 100,000 fresh tonsil samples over the next three years or so. But critics point out that many of the samples will come from people too young to have eaten contaminated beef.
This study will also look at gene variations in those who test positive. All victims so far have the so-called M/M genotype, found in 37 per cent of the general population. Some researchers speculate that vCJD might take longer to emerge in people with other variations, leading to new waves of cases.