Stories and News Our campaigns Measles FAQ How do you get encephalitis from measles Encephalitis can occur either during or after a measles infection. This can happen as a result of the brain becoming infected with the virus during the rash phase of the illness or by an immune-mediated brain inflammation subsequent to measles infection. (1) There are different types of measles encephalitis depending on the stage of the rash. (2) Primary measles encephalitis when encephalitis is concurrent with measles infection (the brain becomes infected during the rash phase of the infection). Acute post-measle encephalitis when encephalitis is caused by immune-mediated brain inflammation subsequent to measles infection (occurs 2–30 days after infection). Measles inclusion body encephalitis most commonly occurs in immunodeficient children (within 1 year of measles infection). It leads to death in 75% of cases. Subacute sclerosing panencephalitis (SSPE) is a progressive and fatal central nervous system disease occurring following reactivation of the measles virus (6-15 years after measles infection).