Herpes zoster or shingles results from reactivation of latent varicella zoster virus (VZV) from sensory nerve root ganglia, where it has remained dormant following varicella or chickenpox earlier in life.
- It occurs more frequently in people over the age of fifty and in those with compromised immunity.
- It presents as a unilateral vesicular rash in a dermatomal distribution. It occurs most commonly in the thoracic region and on the face and neck. Pain in a dermatomal distribution can precede the appearance of the rash by one or two days.
- It is associated with pain (acute herpetic neuralgia) that can be severe, leading to the description 'a belt of roses from Hell'.
- The rash normally dries and crusts in 7 to 10 days but may take a month to heal; resolution may be slower in patients with lowered immunity.
- Herpes zoster of the face involves the ophthalmic divisions of the trigeminal nerve and can be complicated by keratitis and uveitis. Prophylactic therapy for the eye needs to be given and assessment by an ophthalmologist is advisable.
- It may progress and cause disseminated infection. Cutaneous dissemination causes a rash similar to varicella or chickenpox; the presence of a few skin lesions outside the primary or adjacent dermatomes is not unusual or important.
- Visceral dissemination can manifest as encephalitis, transverse myelitis, hepatitis or pneumonitis.
- Patients with herpes zoster are infective to persons who have not had varicella or chickenpox, until such time as all the lesions have dried.

Treatment is with antiviral therapy (e.g. aciclovir, valaciclovir, famciclovir), which should be started within 48-72 hours of the onset of the rash. This will improve the rate of healing and reduce the severity of acute pain; it may also reduce the incidence and duration of postherpetic neuralgia (PHN).

Woodruff R. Palliative medicine evidence-based symptomatic and supportive care for patients with advanced cancer. Fourth edition. Oxford University Press, 2004. (p. 353)