Herpes zoster is a reactivation of latent varicella-zoster virus (VZV) in sensory ganglia, producing a unilateral, dermatomal vesicular eruption with neuropathic pain. Complications include postherpetic neuralgia (PHN), ophthalmic zoster with vision-threatening keratitis/uveitis, and neurologic sequelae. Prompt antiviral therapy within 72 hours of rash onset shortens disease and reduces complications; vaccination (recombinant zoster vaccine, RZV) is highly effective for prevention, including in immunocompromised adults.
Epidemiology and Risk Factors
- Lifetime risk ~30%; incidence increases with age and immunosuppression.
- Risk factors: older age, hematologic malignancy, HIV, immunosuppressive therapies (e.g., JAK inhibitors, anti-TNF, chemo), stress/trauma to dermatome.
Clinical Features
- Prodrome: localized dermatomal burning/tingling, malaise, headache.
- Rash: grouped vesicles on erythematous base in 1–3 adjacent dermatomes, strictly unilateral; evolves to pustules/crusts over 7–10 days.
- Zoster ophthalmicus (V1 trigeminal): forehead/upper eyelid; Hutchinson sign (tip of nose) predicts ocular involvement.
- Zoster oticus (Ramsay Hunt): ear vesicles with facial palsy, hearing loss, vertigo.
- Disseminated zoster: >20 lesions outside primary dermatome or visceral involvement (immunocompromised).
Differential Diagnosis
- HSV (recurrent, non-dermatomal; positive Tzanck/NAAT), contact dermatitis, impetigo, insect bites, dermatitis herpetiformis, bullous pemphigoid in elderly.
Diagnosis
- Clinical; confirm with VZV PCR from vesicle fluid or swab of lesion base when needed (atypical cases, immunocompromised, ocular/visceral disease).
Management
- Antiviral therapy (ideally within 72 hours of rash onset; still treat beyond if new lesions, severe pain, or complications)
- Acyclovir 800 mg five times daily × 7 days.
- Valacyclovir 1000 mg three times daily × 7 days (preferred for convenience).
- Famciclovir 500 mg three times daily × 7 days.
- IV acyclovir for disseminated, ophthalmic with severe involvement, neurologic complications, or in immunocompromised hosts.
- Pain control
- NSAIDs/acetaminophen; short-course opioids for severe acute pain.
- Neuropathic agents for acute pain or PHN: gabapentin/pregabalin; TCAs (nortriptyline) as appropriate.
- Topicals for PHN: lidocaine 5% patches, capsaicin 8% patch in specialized settings.
- Special scenarios
- Zoster ophthalmicus: urgent ophthalmology referral; oral antivirals promptly; topical ophthalmic therapy per ophthalmology; consider IV in severe disease.
- Ramsay Hunt: antivirals plus systemic corticosteroids within 72 hours may improve facial nerve recovery; ENT/neurotology referral.
- Immunocompromised/disseminated: hospitalize for IV acyclovir; airborne/contact precautions until all lesions crusted.
- Prevention: Vaccination
- Recombinant zoster vaccine (RZV, Shingrix): two doses 2–6 months apart; recommended for adults ≥50 years and immunocompromised adults ≥19 years. High efficacy for preventing zoster and PHN.
- Can vaccinate after zoster episode once acute illness resolves; no minimum interval required by many guidelines, though some clinicians wait ~6 months.
- Counseling
- Contagious via vesicle fluid to VZV-naïve contacts (causes varicella, not zoster); cover lesions, avoid contact with pregnant, neonates, and immunocompromised until crusted.
- PHN risk increases with age; early antivirals and pain control may reduce risk.
References (recent guidelines and reviews)
- CDC/ACIP and IDSA guidance on zoster management and vaccination, 2022–2024.
- RCTs comparing valacyclovir/famciclovir vs acyclovir for acute zoster and PHN reduction, 2021–2024.
- Ophthalmic zoster management statements, 2022–2024.