The rogue protein is thought to have two different shapes: a healthy shape which has an unknown function, and a malign shape which causes the disease. Simply by folding in a different way, the unhealthy form of the protein acts as a template for other healthy proteins and makes them fold in this dangerous way too. So ingesting one of these tiny molecules, or inheriting a faulty gene which causes the protein to be folded in the the wrong way or having just one molecule fold the wrong way by chance causes other healthy proteins to fold the wrong way too.
However not everyone believes this and the two main scientists involved - Stanley Prusiner and Carleton Gajdusek - are controversial figures. Both, the book says, are egoists. Gajdusek, who won the Nobel Prize for medicine for his work on Kuru in New Guinea, is a maverick character who spurns western philosophy and has been jailed for pedophilia (after importing and caring for 56 Melanesian and Micronesian preteens); while Prusiner seems to be intensely competitive and when 'asked by the New England Journal of Medicine to judge a paper submitted by Paul Brown. Prusiner recommended that the NEJM reject it and then submitted a similar one based on his lab's work...'. The book later points out that in today's age it is necessary for the researcher to be entrepreneurial and form alliances to keep his work going - which seems to go some way towards a justification for this behaviour.
In fact it is to the credit of the author of this book that he presents these unsavory characteristics of the scientists involved and yet never makes them out to be villains. His approach is balanced - because he shows that both of these men also have hugely admirable qualities - and these weaknesses of character make them somehow endearing and human, at least to me.
Chapter 9 goes back to the unfortunate Italian family and the members that died just fifteen years ago. At each stage the mystery unravels a little more according to the advances in medical knowledge and equipment available. The EEGs of the patients show that their quality of the 'sleep' that they have it strange; it goes from wakefulness to REM and during this REM sleep there is none of the usual paralysis - the patients remain mobile and restless. The EEGs also show a ressemblance to the EEGs of people with CJD and hence there is the first indication that this might be a prion disease too.