Herpes Zoster

Overview – Herpes Zoster

Herpes zoster, also known as shingles, is a reactivation of latent varicella-zoster virus (VZV), which remains dormant in dorsal root ganglia following a primary varicella (chickenpox) infection. It presents as a painful, unilateral vesicular rash in a dermatomal distribution, typically in older adults or immunocompromised individuals. Early diagnosis and antiviral treatment are essential to reduce complications such as postherpetic neuralgia.

Definition

Herpes zoster (shingles) is a reactivation of latent VZV infection, resulting in a painful, vesicular rash affecting one or more dermatomes.

Aetiology

• Caused by reactivation of Varicella-Zoster Virus (VZV)
• Occurs when immunity wanes, especially:
  • In older adults
  • In immunocompromised states (e.g. HIV, chemotherapy)

Pathophysiology

• Following primary varicella infection, VZV enters a latent phase in the dorsal root ganglia
• Reactivation → viral replication and travel down peripheral sensory nerves
• Inflammation of the affected nerve and skin causes pain and dermatomal rash
• Incubation period: ~2 weeks from reactivation

Clinical Features

• Painful, unilateral vesicular rash in a dermatomal distribution (often thoracic)
• Prodromal symptoms:
  • Burning, tingling, or shooting pain
  • Fever, malaise, headache
• Vesicles evolve into pustules and crust over within 7–10 days
• Lymphadenopathy in the regional drainage area
• Possible complications:
  • Nerve palsies (e.g. facial nerve → Ramsay Hunt syndrome)
  • Postherpetic neuralgia (persistent pain >3 months)

Diagnosis

• Usually a clinical diagnosis based on rash and pain
• Confirmatory tests if needed:
  • VZV-specific serology (IgM or IgG)
  • Polymerase chain reaction (PCR) of vesicle fluid

Transmission

• Herpes zoster is infectious, but less so than chickenpox
• Transmission:
  • Through direct contact with vesicle fluid
  • Can cause chickenpox (not shingles) in non-immune individuals

Management

• Antiviral therapy (ideally within 72 hours of rash onset):
  • Oral aciclovir, valaciclovir, or famciclovir
• Analgesia:
  • NSAIDs, paracetamol
  • Neuropathic pain agents if postherpetic neuralgia develops
• Supportive care:
  • Rest, hydration
  • Cool compresses on affected skin
• Consider hospital admission for:
  • Immunocompromised patients
  • Disseminated zoster
  • Ophthalmic or facial involvement

Complications

• Postherpetic neuralgia
• Secondary bacterial infection of skin lesions
• Ocular involvement (Herpes zoster ophthalmicus)
• Cranial nerve involvement (e.g. Ramsay Hunt syndrome)
• Meningoencephalitis or vasculitis (rare)

Summary – Herpes Zoster

Herpes zoster, or shingles, is the result of varicella-zoster virus reactivation, causing a painful, dermatomal vesicular rash. Prompt antiviral therapy can reduce symptom severity and prevent complications such as postherpetic neuralgia. For broader dermatological context, see our Skin & Dermatology Overview page.