I think this is a very interesting finding, EBV is clearly not mostly benign anymore and ME/CFS has some interesting similarities to MS and doctors often struggle to rule it out early on in the disease.
They used two decades of blood samples from more than 10 million young adults on active duty in the U.S. military (the samples were taken for routine HIV testing). About 5 percent of those individuals (several hundred thousand people) were negative for Epstein-Barr when they started military service, and 955 eventually developed MS. The researchers were able to compare the outcomes of those who were subsequently infected and those who were not.
These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS,
The bottom line is almost: if you’re not infected with EBV, you don’t get MS. It’s rare to get such black-and-white results.
After infection, Epstein-Barr lives on in some B cells of the immune system and the antibodies developed to fight it remain in the blood.
Ascherio and his colleagues also measured antibodies against cytomegalovirus, another herpesvirus, and found no difference in levels in those who developed MS and those who did not