Posted 4/2/2015 4:12 AM (GMT 0)
95% of the world's population has EBV. If you ever had mono you will have high IgG titers indefinitely. Reactivation is usually determined by an IgM titer response. Some doctors, such as Jose Montoya at Standfords CFS clinic, believe a high IgG can be an indicator of an active infection, but I don't believe this is any evidence to support this.
FWIW, I was given a CFS diagnosis before I found out I had Lyme. Based on my elevated IgG they treated me with acyclovir and I stopped after a month because I saw no improvement and it was tearing up my stomach.