Answer
Answer 17-20. The most common causes of chronic encephalitis are viral - HIV, myxovirus (progressive multifocal leukoencephalopathy) or subacute sclerosing panencephalitis (the measles virus). Creutzfeldt-Jacob disease is a subacute infectious disease in which a prion is infectious particle. This usually produces a subacute dementia with minimal signs of infection and no meningeal signs.