Herpes Zoster (Shingles)

Introduction

Herpes Zoster also known as shingles is a second infection with varicella-zoster virus (VZV), usually in adults and limited to a dermatome. It occurs with reactivation of the varicella-zoster virus, a chickenpox virus.

Symptoms and Clinical features shingles

  1. Vesicles arranged in one or more dermatomes unilaterally
  2. Initial pruritus, pain and paraesthesia
  3. Multidermatomal and disseminated forms may occur in immuno-compromised states especially HIV infection
  4. The whole episode may last 2 weeks
  5. The early rash is vesicular, later becomes pustular and then ulcerates

Differential diagnosis

  • Chicken pox

Complications of shingles

  1. Pain may persist long after rash has healed (post-herpetic neuralgia)
  2. Dissemination of infection in the immunocompromised
  3. Hemorrhagic and necrotic lesions
  4. Ramsay-Hunt syndrome (Herpes zoster of the ear resulting in severe ear pain, hearing loss and vertigo)
  5. Visual impairment due to corneal ulcers (Zoster ophthalmicus-V1)

Investigations

  • HIV screening for all patients
  • Full Blood Count with differentials
  • ESR
  • Exclude Hodgkin’s disease and leukaemia

Treatment for shingles

Treatment objectives

  1. Provide symptomatic relief
  2. Treat secondary infection
  3. Treat any identified predisposing factor

Drug treatment

Drying agents e.g. zinc oxide 5% (calamine) lotion

  • Apply twice daily

Aciclovir

  • Adult: 800 mg orally five times daily for 5-7 days
  • Continue for at least 3 days after complete healing
  • Child: 12-18 years: 5 mg/kg orally every 8 hours usually for 5 days

Or:

Aciclovir cream 5%

  • Adult apply five times daily for 5-10 days
  • Child: not listed for this indication in children

Oral antibiotics to treat or prevent secondary bacterial infection

Herpetic neuralgia

  • Amitriptyline 10-25 mg orally initially, gradually increased to 75 mg daily

Or

  • Pregabalin: Start with 75mg bid or tid, gradually increase dose depending on efficacy and tolerabilty to a maximum of 600mg per day in divided doses

Notable adverse drug reactions, caution

Aciclovir

  • Ensure adequate hydration
  • Caution in pregnancy and breastfeeding
  • May cause nausea, vomiting, dizziness
  • Fatigue pruritus and photosensitivity

Pregabalin

  • Hypersensitivity reactions
  • Ataxia, dizziness
  • Suicidal tendencies
  • Blurred vision
  • Muscle spasms
  • Peripheral edema