A 20 year old presents with a 72 hour history of headache, photophobia and fever. On examination he is alert and orientated and has mild neck stiffness. There are no focal neurological signs. He has no significant past medical history. He has no risk factors for HIV nor does he have any history of travel to tropical areas.
A CT scan of his head is normal.
A lumbar puncture is performed and a CSF sample is taken.
The initial CSF results are as follows:
- Clear and colourless macroscopically
- White cell count: 85 x 10^6/l, differential 99% lymphocytes
- Red cell count: 14 x 10^6/l
- Protein 0.7 g/l
- Glucose 4.2 mmol/l (serum glucose 6.5 mmol/l)
- Gram Stain: No organisms seen
The following morning he is feeling a bit better, with supportive and symptomatic treatment alone.
1) What is the likely cause of this young man’s illness?
2) What further testing should be undertaken on the CSF sample?
Click here for the answers and brief explanations.