Is there a link between mad cow's disease (bovine spongiform encephalopathy) and the virus Creutzfeldt Jakob disease (CJD), which causes the brain to degenerate?

Britain is in the middle of a national panic over mad cow's disease, with beef and hamburgers being boycotted in restaurants and butchers. Recently, two cases of CJD were reported in teenagers, adding to only four cases ever before affecting such a young age group, while four farmers have died from CJD, which some doctors put down to an occupational hazard.

Evidence already points to a link between CJD and scrapie, a common disease in sheep.

Prof Heino Diringer, from the Robert Koch Institut in Berlin, Germany, believes a link can be made, as mad cow's disease and scrapie are similar in their make up. He proposes that CJD is always transmitted from an infected animal to humans, with early onset of severe dementia as the predominant characteristic (The Lancet, November 4, 1995).

In a separate article, Prof Jeffrey Almond from the University of Reading in England concludes that mad cow's disease is not the cause of CJD in humans. Although he accepts that farmers are at higher risk from developing CJD, this is not because of the disease in animals.

Farmers are also at risk in other countries where mad cow's disease is non-existent. He also believes more research needs to be carried out to determine if mad cow's disease can be transmitted to humans (BMJ, November 25, 1995).