I know I can just make something up, but I would much rather at least start with something rooted in reality. Hence my turning to you, good comm members.
I found a tremendously useful Wikipedia article on prions so I know how they function and spread in an infected person. I also know from my good friend Mayoclinic.com that Creutzfeldt-Jakob Disease ('Mad Cow' in humans) can be diagnosed by spinal fluid taps and at least occasionally a biopsy of the tissue of the tonsils, because both will show the presence of the proteins (prions) responsible for the disease.
So here's the question: Is it plausible to have a prion-caused disease specifically engineered to not be discoverable from spinal fluid or tissue? I need a way to 'hide' them somehow from the above tests.
I have no problem with the infected person showing symptoms of brain damage (the story depends on it), but I need what the heck's specifically wrong with the guy to be a mystery long enough to make curing the disease questionable. And again, I don't feel comfortable just winging it with technobabble, so suggestions would be great.
Thank you very much. :D