Epidemiology of subacute sclerosing panencephalitis in Okinawa, Japan (1977-2005)

Abstract

The epidemiology of subacute sclerosing panencephalitis (SSPE) has changed since the introduction of measles immunization in 1970's. We studied the incidence of SSPE in Okinawa. There were 22 cases (16 males and 6 females) of SSPE from 1977 to 2005 in Okinawa. The incidence was 0.63 per million population per year from 1977 to 1986, 0 from 1987 to 1993, 1.17 from 1994 to 1999 and 0.75 from 2000 to 2005. Twenty-one SSPE patients had a history of non-immunized measles and 19 of them (90%) had measles infection under 2 years of age. There were measles epidemic every 2-5 years in Okinawa. Ten of 21 cases contracted measles in 1990-1991. The percentage of patients with measles infection under 2 years of age during measles epidemics ranged from 46% to 56%. Early measles infection (under 2 years of age) is a risk factor for SSPE. Routine measles immunization to prevent measles infection is very important for the prevention of SSPE.