Treatment of Varicella-Zoster Virus (VZV) Infection
For VZV encephalitis, treat with intravenous acyclovir 10-15 mg/kg three times daily for up to 14 days, with consideration of corticosteroids if there is vasculopathy or stroke. 1, 2
Clinical Presentation Determines Treatment Approach
VZV causes distinct CNS manifestations that require different management strategies:
VZV Cerebellitis
- No antiviral treatment needed 1, 2
- Self-limiting condition resolving in 1-3 weeks
- Primary pathogenic process is immune-mediated demyelination rather than direct viral cytopathology
- Supportive care is sufficient
VZV Encephalitis (Primary or Reactivation)
Intravenous acyclovir is the cornerstone of treatment:
Dosing: 10-15 mg/kg three times daily 1, 2
- In children aged 3 months-12 years: standard weight-based dosing
- In children >12 years and adults: 10-15 mg/kg three times daily
- Most clinicians use 10 mg/kg dose despite VZV being less sensitive to acyclovir than HSV 2
- The 15 mg/kg dose is suggested only if renal function is normal, but requires frequent renal monitoring 2
Duration: Up to 14 days, especially if started within a few days of symptom onset 1, 2
Renal adjustment: Mandatory for patients with impaired renal function 2
Corticosteroid Use
Add corticosteroids in specific circumstances:
- Strongest indication: VZV vasculopathy presenting with stroke-like episodes 1
- Consider for: Encephalitis with inflammatory lesions 1, 2
- Typical regimen: Prednisolone 60-80 mg daily for 3-5 days 1
- The evidence supporting corticosteroids is limited but they are routinely used due to the inflammatory nature of VZV vasculopathy 1
Special Populations
Immunocompromised Patients
- May require prolonged courses of intravenous acyclovir 1, 2
- Higher risk of disseminated disease and mortality 3
- Early diagnosis and treatment are critical for survival 3
Ocular VZV (Conjunctivitis)
- Topical antivirals alone are not helpful for VZV conjunctivitis 4, 5
- For persistent/recalcitrant disease in immunocompetent patients:
Important Clinical Caveats
Acute Kidney Injury Risk
Recent data shows that 37% of patients receiving intravenous acyclovir for VZV CNS infection develop acute kidney injury 6. This underscores the importance of:
- Careful renal function monitoring
- Appropriate dose adjustment
- Adequate hydration
Acyclovir Resistance
While rare, acyclovir-resistant VZV can emerge, particularly with prolonged use in immunocompromised patients 7, 8. In such cases:
- Famciclovir may still be effective in early resistant phases 8
- Alternative agents targeting different mechanisms (e.g., helicase-primase inhibitors like amenamevir) are emerging 7
When NOT to Treat
Intravenous acyclovir is widely overprescribed when VZV DNA is detected in CSF 6. Consider withholding treatment in:
- Isolated VZV meningitis without encephalitis features
- Patients with VZV DNA in CSF but no definite CNS involvement
- However, this remains controversial and requires careful clinical judgment
Transfer Criteria
Transfer to a specialist neuroscience unit is recommended when:
- Diagnosis is not rapidly established
- Patient fails to improve with therapy
- Transfer should occur within 24 hours of being requested 1