Treatment of Herpes Simplex Virus (HSV) Infections and Herpes Simplex Encephalitis (HSE)
For HSV encephalitis, intravenous aciclovir 10 mg/kg every 8 hours for 14-21 days is the recommended first-line treatment, with treatment initiated immediately upon clinical suspicion to reduce mortality from over 70% to less than 20-30%. 1
HSV Encephalitis Treatment
Dosing and Administration
- Adults and children >12 years: 10 mg/kg IV every 8 hours 1, 2
- Children 3 months-12 years: 500 mg/m² IV every 8 hours 1
- Neonates: 20 mg/kg IV every 8 hours 1
- Duration: 14-21 days, with minimum 21 days for children 3 months-12 years due to higher relapse rates 1
Critical Treatment Considerations
- Treatment should begin immediately upon clinical suspicion of HSE, without waiting for diagnostic confirmation 1, 3
- Early initiation significantly improves outcomes, with mortality decreasing to 8% if therapy starts within 4 days of symptom onset 1
- Dose adjustment required in patients with renal impairment 1, 2
- Maintain adequate hydration to prevent crystalluria and nephrotoxicity 1
Monitoring During Treatment
- Regular assessment of renal function, neurological status, and fluid balance 1
- Repeat lumbar puncture with HSV PCR testing at the end of treatment to confirm resolution 1
- CSF PCR remains positive for 7-10 days after starting aciclovir 1
Other HSV Infections Treatment
HSV Meningitis
- IV aciclovir 10 mg/kg every 8 hours for 10-14 days 1
- Shorter courses sometimes used for recurrent HSV-2 meningitis 1
Mucocutaneous HSV in Immunocompetent Patients
- Standard oral aciclovir therapy: 200 mg orally, five times a day for 3-5 days 4
- For poor response, increase to 800 mg five times a day 4
Mucocutaneous HSV in Immunocompromised Patients
- Initial therapy: aciclovir 250 mg/m² every 8 hours (750 mg/m²/day) for 7 days 2
- For genital herpes: IV aciclovir 5 mg/kg every 8 hours for 5 days 2
Varicella-Zoster Virus (VZV) Infections
VZV Encephalitis
- IV aciclovir 10-15 mg/kg three times daily, with or without corticosteroids 5
- Stronger case for corticosteroids if vasculitic component present 5
VZV Cerebellitis
- No specific antiviral treatment needed as disease is usually self-limiting 5
Immunocompromised Patients with Zoster
- Aciclovir 500 mg/m² every 8 hours for 7 days 2
Management of Aciclovir-Resistant HSV
For Poor Response to Standard Therapy:
- Increase oral aciclovir to 800 mg five times daily 4
- If no response after 5-7 days:
- Obtain cultures for viral, fungal, and bacterial pathogens
- Order aciclovir susceptibility studies if available
- For accessible lesions: apply trifluridine ophthalmic solution 3-4 times daily
- For inaccessible lesions or poor response: IV foscarnet 40 mg/kg three times daily or 60 mg/kg twice daily for 10 days 4
- Consider IV cidofovir or topical cidofovir ointment (1-3%) if foscarnet fails 4
Common Pitfalls to Avoid
- Delaying treatment while waiting for diagnostic confirmation - treatment should begin immediately upon clinical suspicion 1, 3
- Incorrect aciclovir dosage - ensure proper weight-based dosing 1
- Stopping treatment based on a single negative CSF PCR - follow complete treatment course 1
- Using oral instead of IV aciclovir for encephalitis - IV formulation is essential for CNS penetration 1
- Inadequate hydration leading to renal toxicity 1
- Routine use of corticosteroids in HSV encephalitis - only consider for marked cerebral edema under specialist supervision 1
ICU Considerations
- Patients with falling consciousness require urgent ICU assessment for:
Early diagnosis and prompt treatment with appropriate doses of aciclovir remain the cornerstone of HSV/HSE management, with treatment modifications based on clinical response and specific patient factors.