<prompt> Subacute Sclerosing Pan Encephalitis SSPE is a complication of:MeaslesMumpsRubellaChicken pox  <response>: Measles: Cause : RNA paramyxovirus. Incubation period: 10-14 days. Source of infection: Cases . Mode of transmission : Respiratory air droplets. Period of communicability : 4 days before 5 days after rash. Pathognomic clinical feature : Koplik spot . Clinical feature : Retro-auricular origin of rash. MC complication : Serous otitis media. Subacute sclerosing pan encephalitis is a rare,late complication of measles - Aka dawsons disease, Dawsons encephalitis. Vaccine : Live attenuated ; Edmonsten zagreb strain. 