Multiple Sclerosis

Abstract

(Second of Two Parts)EpidemiologyApproximately 200 studies of the geographic distribution of multiple sclerosis have been conducted.⁶⁰ They have shown regions of high prevalence (30 to 80 cases per 100,000 population) in northern Europe between 65 and 45° north latitude and in the northern United States and southern Canada, as well as in southern Australia and New Zealand. In contrast, regions of low risk, including most of Asia and Africa, have a prevalence of 5 or fewer cases per 100,000. In both Europe and North America, where the disease has been thoroughly evaluated, a clear north—south geographic gradient has . . .