Few recent influences in neurology are as poorly appreciated as epidemiology. This discipline is concerned with the determinants of disease in populations rather than individuals. Application of its principles established the nature of kuru and the crucial role of hypertension in most cases of stroke.
Though begun 50 years ago, such inquiry into the pathogenesis and etiology of multiple sclerosis has borne fruit only in the past two decades. It has been shown that the disease is geographically distributed and its highest incidence is in those parts of Europe and America north of the 40th parallel.
Uri Leibowitz and Milton Alter extended the quest for an explanation of the factors underlying the distribution of multiple sclerosis into Israel where the diverse origins of the Jewish population of that compact country permitted simultaneous study of natives, Sephardim from Africa and Asia, regions of low incidence, and Ashkenazim from central Europe, where