Herpes Zoster, more commonly known as shingles, is a viral rash caused by reactivation of the Varicella Zoster virus (VZV). This is the same virus that causes chickenpox or Varicella. After the primary chickenpox infection, VZV remains dormant in the dorsal root ganglia cells. When reactivated it migrates down along a nerve root causing the typical rash seen in herpes zoster. It is not clear what specifically triggers a reactivation of VZV, but shingles is more common in individuals who are immunocompromised, and those over the age of 65.
Affected individuals commonly present with severe pain along the affected nerve, most commonly involving Cervical, Thoracic and Lumbosacral nerves. The patient will also develop a vesicular rash in a dermatomal distribution, with onset of the rash usually occurring between day 1 -3 of infection. This type of rash is pathognomonic of Herpes Zoster. Patients may also report fever, myalgia, arthralgia, headaches, and lymphadenopathy. The rash usually heals over 2-4 weeks.
Herpes Zoster is most often a clinical diagnosis. If there is any uncertainty a viral swab can be taken, however this should not delay treatment. You cannot catch shingles or develop shingles without having had a primary chickenpox infection. However, individuals who have not had chickenpox can develop chickenpox following contact with a Herpes Zoster rash while is it discharging fluid (i.e., before the lesions have dried up). Individuals who develop shingles should avoid contact with pregnant women who have not had chickenpox, anyone who is immunocompromised, and babies less than 1 month old.
Treatment is with Valacyclovir. Doses and duration of therapy will vary according to whether or not the patient is immunocompromised. A shingles vaccine is available (vaccination programme varies between countries) which can reduce the risk of developing shingles and reduce severity of symptoms if you do develop it.
Potential complications include:
- Post herpetic Neuralgia
This is characterised by the persistence of pain along the nerve 1 month after symptom onset. This is particularly common along facial nerves and patients will often report a burning or itching sensation along the distribution of the nerve. Increasing age is a risk factor for developing post herpetic neuralgia. Early treatment with Valacyclovir is thought to reduce the instance of post herpetic neuralgia.
- Ramsay Hunt Syndrome
This is characterised by unilateral facial weakness and a rash on the ipsilateral side. The rash can often be found inside the mouth or onside the ear.
- Ophthalmic Complications
If someone presents with shingles in a peri-orbital distribution an urgent ophthalmology opinion should be sought.