Herpes Zoster (Shingles)

Herpes zoster (shingles) is a reactivation of latent Varicella-Zoster Virus (VZV), the same virus responsible for chickenpox (varicella).

• Following a primary varicella infection, VZV becomes dormant in sensory dorsal root ganglia.

• Reactivation occurs when cell-mediated immunity wanes, which may be due to aging, immunosuppression, stress, malignancy, or certain medications.

• The disease is characterized by painful, unilateral vesicular eruptions in a dermatomal distribution, rarely crossing the midline.

• Most commonly affects thoracic dermatomes, followed by trigeminal and cervical dermatomes.

• Complications can include post-herpetic neuralgia, secondary bacterial infections, ophthalmic involvement, and neurological sequelae.

Epidemiology:

• Incidence increases with age >50 years.

• Immunocompromised individuals, such as those with HIV/AIDS or undergoing chemotherapy, are at higher risk.

Signs & Symptoms

Prodromal phase (1–5 days before rash):

• Severe burning, tingling, or stabbing pain in the affected dermatome

• Malaise, fever, headache, and fatigue may occur

Acute eruptive phase:

• Grouped vesicles on erythematous base following a single dermatome

• Lesions typically do not cross the midline

• Vesicles may progress to pustules, crusts, and erosions

• Severe allodynia and hyperesthesia over the affected dermatome

• Involvement of trigeminal nerve ophthalmic branch can cause ocular complications including conjunctivitis, keratitis, and uveitis

Resolution phase:

• Vesicles crust over in 7–10 days

• Hyperpigmentation may persist for several weeks

• Pain may persist as post-herpetic neuralgia (PHN), especially in older adults

Diagnostic Criteria

Diagnosis is primarily clinical, based on:

• Acute onset of severe burning or shooting pain in a dermatomal pattern

• Grouped vesicular lesions on erythematous base

• Lesions confined to a single dermatome, typically not crossing midline

• History of prior varicella infection or VZV vaccination

• Prodromal symptoms: malaise, fever, or headache

Note: Laboratory confirmation (PCR for VZV DNA, direct fluorescent antibody test, or serology) is rarely required but can be used in atypical cases.

Investigation

• Primarily clinical diagnosis; investigations are usually not necessary

• PCR testing for VZV DNA if:

  • Atypical presentation

  • Immunocompromised patients

• Tzanck smear: may show multinucleated giant cells (less commonly used)

• Ophthalmologic evaluation for suspected herpes zoster ophthalmicus

• Blood work may be warranted in immunocompromised patients to rule out systemic infection

Treatment

Management involves antiviral therapy, symptom relief, wound care, and prevention of complications.

Non-Pharmacological Treatment

• Rest and supportive care

• Cool compresses to affected areas to relieve pain and inflammation

• Maintain skin hygiene to prevent secondary bacterial infection

• Patient education: Avoid scratching lesions; isolate if immunocompromised to reduce transmission risk

Pharmacological Treatment

• Antivirals (first-line): Initiate within 72 hours of rash onset

  • Acyclovir 800 mg PO five times daily for 7–10 days

  • Alternative antivirals: Valacyclovir, Famciclovir (for better compliance)

• Pain management:

  • Analgesics: Paracetamol, NSAIDs for mild pain

  • Neuropathic pain agents: Gabapentin or Amitriptyline if pain persists

Wound Care

• Potassium Permanganate soaks (1:4000, 12 hourly for 3–4 days) to dry lesions and prevent bacterial infection

• Topical antibiotics for secondary bacterial infection:

  • Gentamicin 1% ointment

  • Mupirocin 2% cream 12 hourly

Complications to Monitor

• Post-herpetic neuralgia

• Ocular involvement (herpes zoster ophthalmicus)

• Secondary bacterial infection

• Neurological complications: motor neuropathy, encephalitis, Ramsay Hunt syndrome

Prevention

• Zoster vaccine recommended for adults ≥50 years to reduce risk of shingles and PHN

• Early antiviral therapy during acute shingles reduces the risk of complications

• Prompt pain control to minimize nerve sensitization

Prognosis

• Rash typically resolves in 2–4 weeks

• Pain may persist as PHN, particularly in older adults

• Early antiviral therapy and pain management improve outcomes