Detecting Mad Cow Disease; July 2004; Scientific American Magazine; by Stanley B. Prusiner; 8 Page(s)

Last December mad cow disease made its U.S. debut when federal officials announced that a holstein from Mabton, Wash., had been stricken with what is formally known as bovine spongiform encephalopathy (BSE). The news kept scientists, government officials, the cattle industry and the media scrambling for information well past New Year's. Yet the discovery of the sick animal came as no surprise to many of us who study mad cow disease and related fatal disorders that devastate the brain. The strange nature of the prion - the pathogen at the root of these conditions - made us realize long ago that controlling these illnesses and ensuring the safety of the food supply would be difficult.

As researchers learn more about the challenges posed by prions - which can incubate without symptoms for years, even decades - they uncover strategies that could better forestall epidemics. Key among these tools are highly sensitive tests, some available and some under development, that can detect prions even in asymptomatic individuals; currently BSE is diagnosed only after an animal has died naturally or been slaughtered. Researchers have also made some headway in treating a human prion disorder called Creutzfeldt-Jakob disease (CJD), which today is uniformly fatal.