Incidence of multiple sclerosis in the urban area of Erfurt, Thuringia, Germany

European data on the epidemiology of multiple sclerosis (MS) reveal a continuous increase in the incidence of MS, which does not as yet seem to have reached a plateau at any point in time. No epidemiological data are available from Thuringia, which belonged to the former German Democratic Republic and which was politically separated from the neighbouring epidemiologically well-known areas of Hesse and Lower Saxony. We determined the incidence of MS in the urban area of Erfurt in Thuringia, by prospective identification of patients, with a diagnosis of definite or probable MS between 1998 and 2002. The crude annual incidence was 8.0:100,000, which is the highest rate ever reported for Germany. Our data, showing a high proportion of females with a late disease onset, suggests an increase in female cases with a benign form of MS resulting in an increase in MS incidence. An impact of changing diagnostic procedures inflating the rate has still to be taken into account. Until now it is partly up to speculation whether the observed increase in incidence may be related to emerging new cases, possibly from the pool of prior subclinical MS cases.