Herpes zoster (shingles) - Viral skin infections

Herpes zoster (shingles)

Definition

Herpes zoster or shingles is an acute self-limiting dermatomal vesicular eruption occurring in a dermatomal distribution.

Incidence

Affects 10–20% of the population at some time in their lives.

Age

Incidence increases progressively with age.

Sex

M = F

Aetiology/pathophysiology

Primary infection with the varicella-zoster virus (VZV) causes chickenpox. Like other herpes virus infections, it then remains as a latent infection in the sensory dorsal root ganglia. It is thought that gradual loss of immunity underlies reactivation explaining the increased incidence with age and the association with immunocompromise including HIV.

Clinical features

Pain, tenderness or paraesthesia develops in the distribution of a single dermatome 3–5 days prior to the onset of the rash. Erythema and crops of vesicles then develop in the same dermatomal distribution. Additional discrete non-dermatomal lesions are also commonly found. The vesicles become pustular and then form crusts. They heal over 2–3 weeks leaving scars.

Complications

Corneal ulcers and corneal scarring may result from trigeminal infection with ocular involvement. Dissemination is seen in immunosuppressed individuals. Pos-therpetic neuralgia is found in 5–10% of patients presenting as a continued burning pain.

Investigations

The virus can be isolated from vesicular fluid and identified on electron microscopy.

Management

Adequate analgesia is essential. Aciclovir is effective in shortening the duration of pain when started within 48 hours of the onset of the rash. It should be given parenterally in the immunocompromised.