How can prion diseases be prevented?

Not much: There's not much we can do at present as some forms of prion diseases have to do with genetic mutations. Prion diseases can be transmitted by exposure to prion-contaminated tissues during a medical procedure. Another type of prion disease in humans, vcjd, is acquired by eating beef products obtained from cattle with prion disease. So stay away from beef from places with endemic prion disease.

There are many forms: of Prion disease from Fatal Familial Insomnia to Kuru. Generally speaking I would avoid eating brains form any source (see my editorial in the British Medical Journal Lancet ) also avoid blood products from potentially contaminated sources where there have been cases of Variant CJD (Mad cow disease). Some cases occur through spontaneous mutations, corneal transplants and contaminated allographs.