[Multiple sclerosis: its prevalence and incidence in the population of western Poland]

In five provinces of Western Poland the incidence and prevalence of multiple sclerosis was analyzed in patients living at the place of birth and in patients who had changed their place of residence in these provinces. The results showed that the occurrence of multiple sclerosis in geographic foci is more evident if all patients living in a given area are considered, both those born there and those who had come from other localities.