A 20-year-old female presents with seizures. She is fit and he | Neurology collections 2020

A 20-year-old female presents with seizures.
She is fit and healthy but had been unwell for three days prior to admission with flu-like symptoms.
The patient's friends tell you that prior to the seizure she had become confused and her behaviour had been
out of character.
On examination the patient is post-ictal, with a fever of 39.1°C. She has a pulse of 100 bpm and a blood
pressure of 130/71 mmHg. A CT head shows no abnormalities.
CSF examination shows no organisms, with a white cell count of 353/mm (<5) mostly lymphocytes with a
protein concentration of 2.3 g/l (0.29-1.98) and glucose of 3.2 mmol/l (3.0-6.0mmol/l).
What is the likely diagnosis?