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Dermatology (Skin Conditions)

Herpes Zoster (Shingles)

Reactivation of the Varicella Zoster Virus (VZV), the virus that causes chickenpox, which remains latent in dorsal root or cranial nerve ganglia. Characterized by a painful, unilateral vesicular eruption along a specific dermatome.

Also known as: Shingles

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Referral and warning signs

When to refer

Urgent Ophthalmology Referral: ANY zoster involving the tip/side of the nose (Hutchinson's sign), forehead, or eye itself (suspect HZO). Refer to Hospital/Specialist: Severe/disseminated zoster, Immunocompromised patient, Motor complications (facial palsy), Suspected CNS involvement, Severe pain unresponsive to standard analgesia, Need for IV antivirals.

Red flags

  • Lesions on tip/side of nose, eyelid, or eye itself.
  • Facial drooping.
  • Severe headache, neck stiffness, confusion.
  • Motor weakness in affected dermatome.
  • Widespread (disseminated) lesions.
  • Signs of severe secondary bacterial infection/sepsis.

Signs and symptoms

  • Prodrome (Pre-eruptive): Pain (burning, aching, shooting), itching, tingling, or hyperesthesia along the affected dermatome, lasting 1-5 days (sometimes longer). May have fever, malaise, headache.
  • Eruptive Phase:
  • - Erythematous macules and papules appear along a single dermatome (or adjacent dermatomes).
  • - Vesicles (blisters) develop on the erythematous base within 12-24 hours, often grouped.
  • - Vesicles may become pustular, then rupture and crust over 7-10 days.
  • - Rash is typically unilateral and does not cross the midline.
  • - Associated pain is often significant.
  • Common Locations: Thoracic dermatomes most frequent, followed by cranial (especially ophthalmic division of trigeminal nerve - V1) and lumbar/sacral dermatomes.
  • Post-Herpetic Neuralgia (PHN): Persistent pain (>90 days) after rash heals.

Risk factors

  • Increasing age (>50-60 years).
  • Immunosuppression (HIV/AIDS, malignancy, chemotherapy, transplant, chronic steroids).
  • Physical trauma or stress (possible triggers).
  • Having had chickenpox (required for reactivation).

Diagnosis

Clinical assessment

Diagnosis is usually clinical based on the characteristic unilateral, dermatomal vesicular eruption, often preceded by prodromal pain.

Differential diagnosis

  • Herpes Simplex (can sometimes appear zosteriform, but usually recurs in same non-dermatomal location).
  • Contact Dermatitis (itchy, pattern of contact, may blister but not typically dermatomal).
  • Insect bites (grouped but not dermatomal).
  • Impetigo.
  • Cellulitis (more diffuse redness/swelling).

Investigations

  • Usually clinical diagnosis sufficient.
  • Viral Swab: PCR or Direct Fluorescent Antibody (DFA) test from vesicle fluid can confirm VZV (useful in atypical cases or immunocompromised).
  • Consider HIV testing if zoster occurs in young (<50 yrs) or is severe/disseminated.

Diagnostic criteria

Clinical presentation of unilateral vesicular eruption confined to a dermatome.

Management

Non-pharmacological management

  • Keep lesions clean and dry to prevent secondary bacterial infection (clean with antiseptic like Chlorhexidine 0.05% or dilute H2O2).
  • Apply cool compresses or Calamine lotion for symptomatic relief. (LOC: HC2)
  • Wear loose-fitting clothing over affected area.

Pharmacological treatment

  • Antiviral Therapy: Most effective if started within 72 hours of rash onset. Reduces acute pain duration, speeds healing, may reduce risk/severity of PHN.
  • - Acyclovir: 800mg PO 5 times daily for 7 days. (LOC: HC2/3)
  • - Valacyclovir: 1g PO TID for 7 days (more convenient dosing).
  • - Famciclovir: 500mg PO TID for 7 days.
  • - IV Acyclovir: For severe/disseminated zoster or immunocompromised patients (hospital).
  • Analgesia:
  • - Simple Analgesics: Paracetamol, NSAIDs.
  • - Neuropathic Pain Agents (for acute zoster pain AND PHN):
  • - Amitriptyline: Start 10-25mg PO nocte, titrate up slowly. (LOC: HC2/3)
  • - Gabapentin or Pregabalin.
  • - Carbamazepine (as per UCG).
  • - Opioids (may be needed for severe acute pain).
  • Topical Agents: Calamine lotion. Topical Lidocaine patches/cream (for PHN). Capsaicin cream (for PHN - can cause initial burning).
  • Antibiotics: Only if secondary bacterial infection develops.
  • Herpes Zoster Ophthalmicus (V1 involvement): URGENT OPHTHALMOLOGY REFERRAL + Systemic Antivirals needed. (See OPH chapter).

Monitoring

Monitor lesion healing. Assess pain control. Monitor for complications (secondary infection, eye involvement, PHN).

Complications

  • Post-Herpetic Neuralgia (PHN) - persistent neuropathic pain.
  • Secondary bacterial skin infection.
  • Herpes Zoster Ophthalmicus (involvement of eye -> keratitis, uveitis, glaucoma, vision loss).
  • Ramsay Hunt Syndrome (Facial nerve palsy + zoster in ear canal/auricle).
  • Motor neuropathy (rare).
  • Meningoencephalitis (rare).
  • Disseminated zoster (widespread skin lesions, visceral involvement - mainly immunocompromised).

Prevention

  • Varicella (Chickenpox) Vaccination: Prevents primary infection.
  • Zoster Vaccination (Shingrix preferred, Zostavax older): Recommended for older adults (>50-60 yrs) to reduce risk of zoster and PHN.

Patient education

  • Explanation of shingles as reactivation of chickenpox virus.
  • Antiviral medication purpose (if given <72h) and importance of full course.
  • Pain management options.
  • Lesion care (keeping clean/dry).
  • Contagiousness: Virus can spread to cause chickenpox in non-immune individuals (cover lesions).
  • Symptoms of complications (eye involvement, worsening pain, secondary infection) needing review.
  • Information about Post-Herpetic Neuralgia.
  • Consider Zoster vaccination in future if eligible.

Uganda-specific notes

Herpes zoster is frequently seen, often associated with HIV immunosuppression (may be severe/multidermatomal). Acyclovir is usually the available antiviral. Amitriptyline commonly used for neuropathic pain/PHN. HZO requires urgent eye referral.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 22, Section 22.2.2

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