As if it weren't bad enough that deadly prions can survive boiling and radiation, now comes word that aerosolized forms of the pathogen can enter the nose and find their way to the brain, with fatal consequences. Prions, you may recall, were the reason you avoided beef in Europe in the 1990s. They triggered the infamous mad cow disease epidemic in the U.K., which spread to the rest of Europe and other parts of the world. Prions are proteins that all animals produce, but sometimes, toxic mutant versions are made. These malformed versions can cause ..."