There are a number of diseases that may be caused by MAP including (Blau syndrome, type 1 diabetes, Hashimoto thyroiditis, and multiple sclerosis), but more research is needed:
Was doing some research on MS for a friend and I discovered this interesting link, which posits chlamydia and a number of other pathogens (to MS) as possibilities. davidwheldon.co.uk/ms-treatment1.html
On MAP, I have just tested positive for it. I am waiting on seeing if my GI will prescribe the anti-map abx. I strongly believe it is no coincidence I have crohns that is resistant to treatment and MAP ... MAP doesn't just take advantage of inflammation, it creates inflammation where there was none in cows. And according to Borody" "Its causality has been proven by the standard Koch’s postulates which have been fulfilled by culturing the pathogen from patients with Crohn’s Disease, causing the disease to be reproduced in experimental animals, and then culturing back the bacterium from the experimental animals. Hence, a subset of patients with Crohn’s Disease – estimated to be around 50% - are suffering from this chronic inflammation caused by infection with MAP which is found in milk, water and foods generally. "
Given it is so widespread it may well be in patients with other diseases too, but whether or not it causes the specific neurological etc symptoms of something like MS, I'm not sure. I think from what I've read you need both a certain genetic susceptibility and a MAP infection otherwise it doesn't cause the disease, though I don't know if that is just hypothesis or not.