[Epidemiological aspects of SSPE].

SSPE is neurodegenerative complication of slow measles infection in young children. In developing countries, SSPE has become rare disease because of widespread immunization for measles. However, in under developing countries, it is not rare disease. In Japan, widespread measles vaccination started in 1978. From 1981 SSPE cases declined to about 5 patients per year. We studied 114 cases with SSPE who were still alive in 2003. Incidence of SSPE elevated to near 10 cases per year in 1993-1998 coincident with decline of the rate of immunization for measles. After 1999, the incidence is under 5 cases per year. The immunization rate of young children increased to over 90%, SSPE will become rare disease near future. Future problem will be adult or infant onset of SSPE because of decreasing of anti measles virus titer, SSPE in immunosuppressive state including AIDS or post measles vaccination SSPE.