An interesting question.
The HERV etiology diagnosis is rather recent. Scientific American magazine did an article on it. There is, apparently, a very recent test that defines the infection. And the possibility of a drug treatment. I don't have the issue handy, but I believe it was in one of the specials on the brain. A patient of a doctor friend was recently diagnosed with this curious infection after being told he had Parkinson's.
Many people have these HERV creatures within them, and it appears that there is a co-factor, apparently herpes, that activates them. Once activated, they methodically destroy neurological tissue. They are nasty creatures. Once such way of making a diagnosis is to provide a prednisone challenge. If the body returns to normal, this suggests such an infection.
Would that infection be detectable with blood labs? I've been tested for every infection under the sun, multiple blood cultures, even a gold TB test.
Yes.
My thoughts are, if you are having neurological problems, exclusive of spinal compression. and prednisone provides significant relief, I would suspect an HERV infection. Such an infection causes the immune system to become super-active and attack nerve cells.
Such an infection can lead to eventual paralysis, dementia and Parkinson's like symptoms.