Subacute sclerosing panencephalitis (SSPE) is a rare complication of measles infection[2][3][7]. It is a slow inflammation of the brain caused by a persistent infection with the measles virus, which the immune system has not been able to handle[2][3]. It occurs in approximately 5-10 cases per million diseases[2]. Other sources report an incidence of 1 per 100,000 measles cases[7]. SSPE is a fatal degenerative disease of the central nervous system[7]. It is one of the late consequences of measles along with encephalitis[3][4]. The article is published in the New England Journal of Medicine as a preprint version[1].