The degree of overlap in diagnosis also depends on the diagnostic criteria that was used to make the CFS/ME diagnosis.
True. The same holds true for criteria for Lyme. Allen Steere's disease is tightly defined, with narrow criteria, but many believe this only applies to a strain or two of Bb, and there are literally hundreds of strains. Broaden the diagnostic net for Lyme just a bit, and contract that of ME/CFS and the two are virtually indistinguishable. For instance, what is the difference between ME and Lyme Encephalomyelitis?
Also the likelihood of catching Lyme depends where you live because Lyme ticks don't exists in certain regions like the Sahara desert, whereas with CFS/ME there seems to be no locations reported where the disease doesn't exist.
So, tighten up your definition of ME/CFS, exchange Borrelia for Lyme, and see how the geographies play out - remember, too, that wherever birds fly, Borrelia can be found.
@Mel9, there are a number of us on this forum that have been diagnosed with both Bb and ME/CFS. As for the immune system: Both corrupt it, one by effect, the other by definition (if you accept Lipkin and others). There is absolutely no reason, pragmatically, a person cannot have both.