IT IS widely accepted that diseases such as BSE can be contracted by eating brain tissue from an infected animal. Yet it remains a mystery how similar diseases such as scrapie can spread between sheep that eat nothing but grass, or how chronic wasting disease can spread between wild, free-roving animals like elk. Now, evidence has emerged suggesting that the infectious agents, called prions, could spread when animals lick one another during mutual grooming sessions.
Richard Bessen and his colleagues at Montana State University in Bozeman injected the brains of hamsters with a strain of prion disease that normally infects…
