[rare chronic progressive encephalitis caused by the measles virus and occurring primarily in children and young adults; death usually occurs within three years; characterized by primary measles infection before the age of two years. ( CSP )] (UMLS (CSP) C0038522) =Disease or Syndrome ; =ELGORRIA; Slow Virus Diseases; Paramyxoviridae disease; Encephalitis, Viral; infectious encephalitis; viral myelinopathy; latent virus infection;