Yes, so it seems that just having EBV infection was a risk factor for MS, rather than having persistence of infection and symptoms. That suggests some genetic factor that causes those people’s immune system to respond in a particular way that can lead to MS.

By the way, at one point my son had a very thorough virology panel done at Stanford, looking for antibodies and viral antigen (using PCR), and they found evidence for exposure to dozens of viruses, some of them potentially quite nasty. The point is, we are exposed to so many viruses, some of which can contribute to serious diseases later in life, and yet we know so little about these interactions. It makes me think of Covid and how, yes, it’s a nasty virus and long Covid can be a horrible outcome, but we act like that’s a unique thing. It’s just the one we are paying attention to now.