It's very difficult to diagnose usually they have to do a tissue biopsy of the affected area and you have to catch it in its active state. It goes in phases of active and passive that's why some people have good days and very bad days I can attest to that. I don't believe the pcr assay of the blood is a good indicator because its only in trace amounts in the blood therefore it goes undetected. I'm sure a saliva or stool sample might detect it but it has to be specifically tested for it because if not it will continue to go undetected.