Shingles (herpes zoster infection) is an acute, unilateral, painful blistering rash caused by reactivation of the varicella-zoster virus (VZV). Following primary infection with VZV (chickenpox), the virus lies dormant in the dorsal root or cranial nerve ganglia.

Risk factors

• increasing age
• HIV: strong risk factor, 15 times more common
• other immunosuppressive conditions (e.g. steroids, chemotherapy)

The most commonly affected dermatomes are T1-L2.

Features

• prodromal period
  • burning pain over the affected dermatome for 2-3 days
  • pain may be severe and interfere with sleep
  • around 20% of patients will experience fever, headache, lethargy
• rash
  • initially erythematous, macular rash over the affected dermatome
  • quickly becomes vesicular
  • characteristically is well demarcated by the dermatome and does not cross the midline. However, some 'bleeding' into adjacent areas may be seen

Herpes zoster in the T3 distribution

The diagnosis is usually clinical.

Management

• remind patients they are potentially infectious
  • may need to avoid pregnant women and the immunosuppressed
  • should be advised that they are infectious until the vesicles have crusted over, usually 5-7 days following onset
  • covering lesions reduces the risk
• analgesia
  • paracetamol and NSAIDs are first-line
  • if not responding then use of neuropathic agents (e.g. amitriptyline) can be considered
  • oral corticosteroids may be considered in the first 2 weeks in immunocompetent adults with localized shingles if the pain is severe and not responding to the above treatments
• antivirals
  • NICE makes recommendations on when to use antivirals
  • in practice, they recommend antivirals within 72 hours for the majority of patients, unless the patient is < 50 years and has a 'mild' truncal rash associated with mild pain and no underlying risk factors
  • one of the benefits of prescribing antivirals is a reduced incidence of post-herpetic neuralgia, particularly in older people
  • aciclovir, famciclovir, or valaciclovir are recommended

Complications

• post-herpetic neuralgia
  • the most common complications
  • more common in older patients
  • affects between 5%-30% of patients depending on age
  • most commonly resolves with 6 months but may last longer
• herpes zoster ophthalmicus (shingles affecting affecting the ocular division of the trigeminal nerve) is associated with a variety of ocular complications
• herpes zoster oticus (Ramsay Hunt syndrome): may result in ear lesions and facial paralysis