Sunday, May 23, 2004

Return of the mad cow

'Thousands carrying hidden CJD timebomb', says The Times (London), reporting a new study conducted by Plymouth's Derriford Hospital and the UK CJD Surveillance Unit into infection rates for variant-Creuzfeldt-Jakob disease (vCJD). Researchers tested 12,674 appendix and tonsil samples. Three were found to contain prion proteins that could lead to the development of vCJD, often called the human form of mad cow disease. Although this is a tiny percentage, extrapolated over the whole country it could mean that 3,800 people are infected. David Hilton, the lead researcher, told the BBC, 'Our findings need to be interpreted with caution, but cannot be discounted.' Reports of the study's findings have raised new fears about the possibility of passing on the infection through blood transfusions and contaminated surgical instruments.

Making this a major news story on television and in the press hardly constitutes 'caution' - but does reflect the lack of reality that has been associated with the mad cow panic.

It is almost impossible to draw any conclusion from these results because the number of positive results is tiny. If this study were repeated on another 12,674 samples, it is highly likely that a different number would come out. On top of this, a number of logical steps need to be taken to conclude that thousands are at risk. Firstly, it would need to be established that these positive tests really do represent vCJD, rather than some other prion protein that causes no harm. Secondly, even if these are vCJD samples, there is no way of knowing how many people would actually develop the disease. A genetic predisposition to develop vCJD may be required.

Even if these reports are accurate, the idea that 0.02 per cent of the population might, over a period of decades, develop this nasty condition suggests there are many more pressing problems that face us. To date, there have been 141 deaths from vCJD in roughly ten years - a far cry from the 'epidemic' of hundreds of thousands that was talked about in the past. Previous research has suggested that around 540 people may die in total from the condition.

This might not matter as a passing news story, except that the effect is to increase the anxiety of patients going into hospital for treatment for real, existing health problems. For one thing, there are likely to be even greater controls on blood stocks. For another, there have been calls to look again at using disposable surgical instruments - despite the fact that these have been withdrawn as unsafe. It's not just the cows that are mad.

Thousands may be harbouring vCJD, BBC News, 21 May 2004

First published on spiked's Don't panic page.

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