Most fatal complication of measles is

SUBACUTE SCLEROSING PANENCEPHALITIS It is a slowly progressive disease characterised by seizures and progressive deterioration of cognitive and motor function. SSPE belongs to group C slow virus infection, caused by a defective measles virus . Age: SSPE typically develops if the primary measles virus infection in childres less than 2 years of age SSPE usually develops after 7-13 years after primary measles infection. High titer antibody to measles virus in CSF is diagnostic Ref : essentials of Medical microbiology apurba sastry 1st edition page 468