The question at Quora was:
My answer was:
A leading hypothesis for the cause of multiple sclerosis is that it’s an autoimmune disease that starts with a genetic predisposition, that’s triggered by a viral infection. It may be a specific virus, but it’s more likely that it can be triggered by any of a wide range of viruses, which may be innocuous on their own and require other genetic and environmental factors to cause MS.
The timing of MS on the Faroe Islands shows a dramatic increase starting in 1943, and waxing and waning over multi-year periods, consistent with a role for an infectious agent:
Multiple sclerosis: variation of incidence of onset over time in the Faroe Islands.
It’s been suggested that British troops spread a very mild virus among the inhabitants that led to the disease among the inhabitants:
Epidemiology in multiple sclerosis: a pilgrim’s progress.
The hypothesis is controversial, and other researchers raise evidence opposing it and supporting a genetic role:
Multiple sclerosis in a family on the Faroe Islands.
However, neither hypothesis seems to fully account for the possibility that both genetics and infectious diseases could be critical factors simultaneously.
In any case, I don’t think that “immune system and the testicles and ovaries” are proposed to be primary targets. I think the model, such as it is, suggests that the primary infection damages nervous tissue and leads to an immune response against the nervous tissue components when people have a certain set of genetic tendencies.
