Multiple sclerosis in the Faroe Islands.

In this century, 41 Faroese with MS were ascertained. One subset, after living in Denmark for 2 years between ages 11 and 31, had MS onset an average of 6 years later. In the Faroes, MS occurred as three separate and decreasing epidemics beginning in 1943 and ending in 1973. We believe that asymptomatic British troops introduced the first epidemic during 1941 to 1942, with the later epidemics resulting from transmission by affected but asymptomatic Faroese. We conclude that "MS" is a widespread, systemic, specific infectious disease only rarely causing neurologic symptoms and transmissible at most from ages 13 to 26.