The incidence and prevalence of multiple sclerosis in Newfoundland and Labrador, 1960-1984.

A study of the incidence and prevalence of multiple sclerosis on the island of Newfoundland between 1960 and 1984 has yielded a current overall prevalence rate of 55.2 per 100,000, but wide variation is noted in the rates for different parts of the island (range, 15.9 to 105.0 per 100,000). The annual incidence rates for St. John's and the Avalon region of Newfoundland show cyclical variation on an approximate five- or six-year cycle. Suggestive evidence for a temporal link between varying incidence rates in these areas and recurrent local outbreaks of canine distemper was obtained.