Herpes Zoster

Shingles — reactivation of Varicella-Zoster Virus (VZV), which remains latent in cranial nerve or dorsal root ganglia after a primary varicella infection.

Aetiology

• Reactivation of latent VZV (HHV-3).

• Triggered when immunity decreases, such as:
• Older age (>50 years)
• Immunosuppression (HIV, malignancy, steroids)
• Stress, trauma, chronic illness

Pathophysiology

• Latent VZV in sensory ganglia reactivates.

• Virus travels along sensory nerves to the skin.

• Causes neuritis + dermatomal rash.

• May lead to postherpetic neuralgia due to nerve damage.

Clinical Presentation

• Burning, tingling, hyperesthesia, severe neuralgic pain

• Fever, malaise (less common)

• Unilateral dermatomal vesicles, not crossing midline

• Vesicles → pustules → crusts within 7–10 days

• Most commonly thoracic dermatomes (T3–L3), followed by trigeminal nerve (V1 ophthalmic)

• Herpes Zoster Ophthalmicus (HZO): involvement of V1 branch → risk of vision loss
Hutchinson's sign: vesicles on the tip of nose (nasociliary nerve involvement)

• Herpes Zoster Oticus (Ramsay Hunt Syndrome):
• Facial paralysis
• Ear pain
• Vesicles in auditory canal

• Zoster Sine Herpete:
• Neuropathic pain without rash

Investigations

• Tzanck smear: multinucleated giant cells (not specific).

• PCR from vesicle fluid (most sensitive)

• Serology (IgM for acute infection, IgG for past immunity)

Management

Supportive Therapy

• Antipyretics (avoid aspirin)

• Antihistamines for pruritus

• Skin hygiene to prevent secondary infection

• Neuropathic pain agents for moderate-severe pain:
• Gabapentin 100 mg 3x1
• Tricyclic antidepressants (amitriptyline) 10 mg
• Opioids (if necessary) — tramadol 50 mg 1x1

First-line Antiviral Therapy

• Acyclovir 800 mg 5x1 (Pediatrics → 10-20 mg/kg 4x1, max 800 mg/day)

• Valacyclovir 1000 mg 3x1

• Famciclovir 250 mg 3x1