https://www.ncbi.nlm.nih.gov/pubmed/29706237?dopt=Abstract The link above is to an abstract of an NIH-backed study that seems to bemoan the nature of patients who, for whatever reason, imagine they have chronic Lyme. Please note the mention of MUS. I find several aspects of this abstract concerning, but in particular the authors seem to readily concede some of this small cohort "declaring themselves to be affected by chronic Lyme disease" not only were in reality diagnosed as such by clinicians, but actually satisfy diagnostic criteria for Lyme. So, positive serology = MUS. This doesn't say much potentially for the 2 Tier or the C6, which together generate something around $500 Million annually, last I checked.