Herpes Zoster

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Introduction

  • A second infection with varicella-zoster virus (VZV), usually in adults and limited to a dermatome

Synonyms: 

  • Zoster, from the Greek "zostrix", meaning belt
  • Shingles, from the Latin "cingulus", also meaning belt

Clinical features

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

Differential diagnosis

  • Chicken pox

Complications

  • Pain may persist long after rash has healed (post-herpetic neuralgia)
  • Dissemination of infection in the immunocompromised
  • Hemorrhagic and necrotic lesions
  • Ramsay-Hunt syndrome (Herpes zoster of the ear resulting in severe ear pain, hearing loss and vertigo)
  • 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 goals

  • Provide symptomatic relief
  • Treat secondary infection
  • 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

Hepatic neuralgia

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

Or:

  • Pregabalin: start with 75 mg twice or thrice daily, gradually increase dose depending on efficacy and tolerability to a maximum of 600 mg per day individed doses

Notable adverse drug reactions, contraindications, and 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 oedema