Figure 1 :Global distribution of multiple sclerosis and migrations The five continents are depicted, showing areas of medium prevalence of multiple sclerosis (orange), areas of exceptionally high frequency (red), and areas with low rates (grey-blue). Some regions are largely uncharted so these colors are only intended to provide an impression of the geographical trends. Major routes of migration studied from high-risk zone of northern Europe are shown as dotted arrows. Studies involving migrants from low-risk to high-risk zones are shown as solid arrows. Reprinted from The Lancet, Vol. 372, Compston and Coles, Multiple sclerosis, 1502-1517, Copyright (2008), with permission from Elsevier.