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Disease Definition

Def. !Meningitis not caused by typical pyogenic bacteria.

• The term “aseptic” means no bacteria are found on standard cultures, although other pathogens or causes may be responsible. </aside>

Infectious (Meningitis → Encephalitis)

• Enteroviruses (e.g., Coxsackievirus, Echovirus) – most frequent in children
• HSV 1/2 (HSV-2) – especially in adults
• VZV (HHV3)
• EBV (HHV 4)
• Arboviruses (e.g., West nile virus )
• Traveller or East Asian South Asian : suspect…
  • Rabies
  • JEV
• Other
  • HIV Infection (especially during seroconversion)
  • Mumps virus (in unvaccinated individuals)
  • Lyme Disease

Non-infectious (less common)

• Medications (e.g., NSAIDs, IVIG , antibiotics like TMP-SMX (Septra) )
• Systemic autoimmune diseases (e.g., SLE - Lupus )
• Malignancy-related (carcinomatous meningitis)

Symptoms

Same as typical meningitis, but often milder:

• +/- Altered mental status (less common than in bacterial meningitis)

Diagnosis

• Viral PCR and Serologies

• Brain MRI if suspect viral

  Virus	Pattern of enhancement	Note
  HSV 1/2	Temporal lobe	High Sensitivity
  VZV (HHV3)	Frontal lobe
  EBV (HHV 4)	Cerebellum
  West nile virus	Thalamus

Treatment

• Supportive care for most viral causes
• Antivirals (e.g., acyclovir) if HSV or VZV is suspected
• Discontinue offending drugs if drug-induced

Prognosis