Synopsis
Differentiate viral meningitis from bacterial, encephalitic and chronic infection, interpret cerebrospinal-fluid PCR with timing and immune status, use antivirals selectively, and stop unnecessary antibiotics only after safe reassessment.
- Viral meningitis usually causes fever, headache, neck stiffness, photophobia and nausea while cognition remains relatively preserved.
- Enteroviruses are common; HSV-2, varicella zoster, acute HIV, mumps and other viruses are selected by lesions, vaccination, season, exposure and immune status.
- Perform lumbar puncture promptly when safe, sending cells, paired glucose, protein, bacterial studies and exposure-directed viral PCR.
Key red flags
Altered behaviour, focal seizure or focal deficit suggests encephalitis rather than isolated meningitis and needs intravenous aciclovir.
Genital lesions, sacral symptoms or recurrent episodes can accompany HSV-2 lymphocytic meningitis, but lesions may be absent.
Investigation priorities
Separate bacterial, viral and chronic meningeal patterns and identify a viral target.
Management branches
A patient presents with a possible aseptic meningitis syndrome.
- Stabilise physiology and examine cognition, focal neurology, skin, eyes and immune status before attributing symptoms to a benign virus.
- Take blood cultures and perform lumbar puncture promptly when safe; start bacterial treatment whenever danger or CSF uncertainty persists.
Key medicines
Supportive analgesiaGive paracetamol 500 mg to 1 g orally up to four times daily, at least 4 hours apart, maximum 4 g daily in a suitable adult.
Intravenous aciclovir for severe HSV or VZV diseaseGive aciclovir 10 mg/kg intravenously every 8 hours using protocol weight and renal adjustment when encephalitis or severe high-risk disease is suspected.