In the Footsteps of Alchemists

摘要

Both the United States and Canada recently reported their first confirmed cases of bovine spongifbrm en-cephalopathy (BSE) in cattle reared within their borders (1). These cases raise the specter of a spread to North America of variant Creutzfeldt-Jakob disease (vCJD), the human analog of "mad cow disease" that has afflicted Europe, particularly the United Kingdom, since the late 1980s. This devastating disease is widely believed to result from the consumption of beef contaminated with a pathogenic form of a normal cellular protein called the prion protein. Although there are grounds to hope that the severity of the European outbreak will be much less than was once feared, its ultimate magnitude is still a subject of intense speculation, as the mechanism of transmission is still unclear and the incubation period of the disease could be many decades (2).