This excellent paper lends weight to the idea that pathogens cause many insidious diseases, in this case Multiple Sclerosis. We recommend you read the whole paper, but if you are short on time, John Kurtzke’s conclusion is as follows:
Is there any way to consolidate in some sensible fashion this mass of material I have gleaned over the last 60 years? How could primary multiple sclerosis affection be the cause of multiple sclerosis? One possible formulation that supports my hypothesis at this point follows as a series of arbitrary and dogmatic statements, each of which could well be presented as questions, but all of which together explain to me this illness:
- Primary multiple sclerosis affection is a specific, persistent gastrointestinal infection, presumably viral, and is the initial stage of clinical multiple sclerosis in a few of those infected;
- Susceptibility to primary multiple sclerosis affection is mostly limited to ∼11–45 years of age, but transmissibility ends after ∼25–30 years of age;
- In natives of high risk multiple sclerosis areas, primary multiple sclerosis affection acquisition requires ∼4 years of exposure from the age of 11 and is likely to be asymptomatic;
- Immigrants from lower to high risk areas require ∼3 years of exposure from age 11 for acquisition, also likely asymptomatic;
- In virgin populations, primary multiple sclerosis affection infection begins as an acute illness acquired by persons of all ages (cf. measles), but persistent primary multiple sclerosis affection requires ∼2 years of exposure, also from the age of ∼11–45;
- Early after acquisition the primary multiple sclerosis affection agent in some of the affected patients starts to cross the gut wall into regional lymph nodes, from which a further fraction then begins a lifelong invasion of the CNS through the blood stream and CSF (cf. acute poliomyelitis); and
- This is a testable hypothesis.
https://academic.oup.com/brain/article/136/9/2904/293020/Epidemiology-in-multiple-sclerosis-a-pilgrim-s