Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Herpes simplex encephalitis ?
    ### Response:
    Herpes simplex encephalitis is a rare neurological condition that is characterized by inflammation of the brain (encephalitis). People affected by this condition may experience a headache and fever for up to 5 days, followed by personality and behavioral changes; seizures; hallucinations; and altered levels of consciousness.
    