The Changing Frequency of Multiple Sclerosis in Israel

A country-wide survey of multiple sclerosis (MS) in Israel showed that the disease was common among immigrants from Europe and rare among immigrants from Afro-Asian countries. Native-born Israelis of either European or Afro-Asian origin had prevalence rates of MS as high as the European immigrants. These findings suggest that the causal factors, which are responsible for the geographic distribution of MS, are environmental rather than genetic, and socioeconomic rather than geoclimatic. The Israeli study suggests that the frequency of MS may change with changing socioeconomic conditions. The study of MS in countries undergoing rapid economic development and in migrant populations may provide clues to the role of specific environmental factors in the cause of MS.