Contents
Overview
Shingles is a usually temporary, self-limiting illness characterised by a painful rash which is caused by the herpes zoster (aka varicella zoster) virus – more specifically human herpesvirus-3 – (HHV-3).
Primary infection with HHV-3 causes chickenpox which is most commonly acquired in childhood but can be acquired at any time in life. The initial infection may be subclinical, especially in those with previous vaccination.
After the primary infection, the virus lies dormant in the central nervous system, in the root ganglia – either the dorsal root ganglia (of the spinal cord), the trigeminal ganglion, or the geniculate (facial nerve) ganglion. An episode of shingles occurs when the virus “reactivates” and travels down the nerve. This causes inflammation along the nerve itself, resulting in pain, and usually a rash – in the dermatome associated with the nerve root in which the virus has reactivated.
- Reactivation is more likely with age – thought to be due to declining cell-mediated immunity
- Other factors include physical or psychological stress (e.g. trauma, depression) and other immunosuppressive illnesses
Common locations include the thoracic region and the ophthalmic division of the trigeminal nerve – which can involve the eye.
- Shingles can occur in almost any location
- Clinically, ophthalmic shingles can be associated with significant consequences, including permanent loss of vision, if not promptly and appropriately treated.
- Facial nerve involvement can result in skin lesion in the ear, hearing and vestibular symptoms and facial paralysis – collectively known as Ramsay-Hunt Syndrome.
The use of antiviral medication (e.g. valaciclovir or aciclovir) can reduce the duration and severity of symptoms when started within 72 hours of the onset of the rash. The earlier the treatment is started, the more likely it is to be of benefit. Any suspicion or evidence of ophthalmic involvement requires urgent ophthalmology referral.
- Mild cases diagnosed after 72 hours of the onset of the rash may not benefit from antivirals
- Always given antivirals to any patient with V1 (ophthalmic) shingles
Most patients recover without any long-term consequences. Pregnant women and immunocompromised patients are at greatest risk, and older patients are at higher risk of complications.
Death is rare but can occur in severely immunocompromised patients, as a result of disseminated disease. For an immunocompromised patient with disseminated disease, the risk of death is 5-15% – usually as the result of pneumonia.
Epidemiology
Primary HHV-3 infection causes chicken-pox. Without vaccination against this disease, it is endemic. 90% of UK adults have been exposed during childhood – therefore 90% of the UK population is at risk of shingles.
- Shingles is typically seen as a disease of older people but can occur at any age
- Risk increases with age
- Affects about 8 per 1000 people aged 70-79 annually in the UK
It is possible to transmit HHV-3 from the vesicular fluid of the rash caused by shingles – therefore it is possible to catch chickenpox from shingles in patients who are not immune. However this is rare, and the risk is much lower than transmitting HHV-3 from a patient with a primary infection. It is NOT possible to ‘catch’ shingles.
Presentation
The critical feature of a shingles rash is the dermatomal distribution (usually only affects a single dermatome) and therefore it also never crosses the midline.
- Pain
- Usually the first symptom
- May be associated with paraesthesia (pins and needles or tingling sensation in the skin)
- Rash
- A vesicular “herpetic” rash
- Fluid-filled vesicles, typically in clusters
- Typically appears 1-3 days after onset of the pain – but can be up to 10 days later
- A vesicular “herpetic” rash
- Duration
- 2-3 weeks in younger patients
- Longer in older patients
- Post-herpetic neuralgia (pain) is a common complication and can last for several months
Differential Diagnosis
- Pain
- Any other cause of chest or abdominal pain – especially during the prodromal phase where pain is the only symptom
- Rash
- Herpes simplex virus and eczema herpeticum – which can affect any part of the body – not just the face and genitals
- Impegito
- Dermatitis herpetiformis – a skin manifestation of coeliac disease – typically affecting the shins – which presents with a herpetic type rash
- Bell’s Palsy may be confused with Ramsay-Hunt syndrome
Investigation
- Diagnosis is usually clinical
- Investigations are not routinely required
- If there is doubt about the diagnosis, then a viral or PCR swab can be sent of any skin lesions to confirm the diagnosis
- Renal function (U+Es) may be considered before starting anti-viral treatment as dose-reduction is required in renal failure
Management
- Keep the rash clean and dry
- Try to keep the rash covered – but avoid adhesive dressings
- If the rash can be effectively covered, then the risk of transmission of HHV-3 is extremely low (compared to primary HHV-3 infection) and school or work exclusion is not required
- Once all the lesions have dried, the rash is no longer infectious
- Topical therapies are not recommended
- Oral antiviral therapy
- Is the mainstay of treatment
- Valaciclovir may be more effective than aciclovir or famciclovir
- Valaciclovir 1000mg TDS for 7 days
- Aciclovir 800mg 5x a day for 7 days
- Famciclovir 500mg TDS for 7 days
- Treatment should be started within 72 hours of onset of the rash
- If this is not possible, treatment may still be effective for certain high-risk groups, even after this time
- Older age
- Severe pain
- Immunocompromised
- Ophthalmic involvement
- In pregnancy – seek specialist advice
- Zoster immunoglobulin-VF can be given if indicated
- Children may not require treatment unless immunocompromised
Complications
Post-herpetic neuralgia
- Pain at the site of the rash. Can persist for several months – long after the resolution of the rash
- The most common complication
- Is not dangerous but can be a significant casue of morbidity
- Can be treated with drugs for neuropathic pain – such as pregabalin (Lyrica®) or amitriptyline
Herpes Zoster Ophthalmicus
- Involvement of the eye in an episode of shingles
- Caused by shingles which affects the ophthalmic branch (V1) of the trigeminal nerve
- Can be serious and sight-threatening and typically requires urgent ophthalmology assessment
- Can affect almost all parts of the eye, eyelid and orbit
- Despite the risk – in most patients it is mild, and may only cause a conjunctivitis
- Iritis and keratitis are significant complications and can be sight-threatening. Signs of these may include:
- Reduced visual acuity
- Photophobia
- White opacities on the cornea
- Corneal swelling causing loss of detail of the iris
- Small pupil
- Marked redness of the eye
- Associated with vesicles on the tip of the nose
- Symptoms typically occur about 10-14 days after the onset of the rash
- Ophthalmic symptoms are also associated with a high risk of postherpetic neuralgia
- Management
- All patients with V1 shingles should be treated with antivirals
- Valaciclovir is thought to be more effective than aciclovir
- Treat for 7-10 days with antivirals
- Topical antibiotics may prevent secondary infection and are often used
- Analgesia
- Consider urgent ophthalmology review (same day or next day) if any signs of iritis or keratitis
- Safetynet for any worsening eye symptoms to seek urgent medical review
Prognosis
Prevention
A vaccination for shingles (Zostavax®) is recommended for everyone over 70 (in the UK and Australia). Given that the risk of shingles increases with age, the vaccine has been proven to reduce the incidence of shingles in those to whom it is given, presumably by boosting the immune response to HHV-3.
Generally, the vaccine is safe and well-tolerated. However, it is a live-vaccine. Care should be taken to ensure patients are not immunocompromised at the time of administration. There are case reports of deaths attributed to the vaccine when it was given to immunocompromised patients.
There are now also vaccination programs for HHV-3 in children to prevent primary infection (chicken-pox). This is now routinely given in the USA and Australia (but NOT in the UK as of August 2020) as part of routine childhood immunisations (in Australia – usually at the age of 18 months).
- In Australia the vaccine used in children is a combination vaccination of varicella, measles, mumps and rubella, known as Priorix® or Proquad®
References
- Shingles – Patient.info
- Shingles – Health Pathways ACT
- Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
- Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
- Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy