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Shingles (also known as herpes zoster) occurs when the varicella-zoster virus (which causes chickenpox) is reactivated from latency in the central nervous system. Diagnosis is usually made on clinical grounds. There is normally a prodromal phase occurring about 1 – 4 days before the rash appears where patient may complain of burning, tingling, numbness, or pruritus in the affected skin. A painful maculopapular rash then develops which evolves into vesicular lesions in a dermatomal distribution (doesn’t cross the midline), most commonly on the thorax. These then burst, releasing the varicella-zoster virus. The rash usually lasts about 7 – 10 days before the lesions crust over and the rash heals.
Individuals who have not had chickenpox or the varicella vaccine can catch chickenpox from the rash – the person is infectious until the lesions have dried (usually 5 – 7 days after onset). Therefore, patients with shingles should be advised to avoid direct skin contact (involving the affected area) with pregnant women, immunocompromised people, and babies younger than 1 month of age (unless it is their own baby, who will have maternally-derived antibodies against the virus). Unlike chickenpox, it is NOT possible to catch shingles through direct skin contact.
An oral antiviral drug (e.g. aciclovir) should be started within 72 hours of rash onset, to reduce pain and severity for:
- Anyone aged 50 years and over.
- People aged less than 50 years with any of the following criteria:
- Ophthalmic involvement (seek immediate specialist advice, or refer immediately).
- Immunocompromised (consider treating in primary care if the rash is localised and they are not
- systemically unwell; seek immediate specialist advice or refer immediately if the rash is severe,
widespread, or multiple dermatomes are involved, they are systemically unwell, or there is severe
- Non-truncal involvement (such as shingles affecting the neck, limbs, or perineum).
- Moderate or severe pain.
- Moderate or severe rash.
If it is not possible to initiate treatment within 72 hours, an antiviral drug should be considered up to one week after rash onset, especially if the person is at higher risk of severe shingles or complications (for example continued vesicle formation, older age, immunocompromised, or in severe pain). Pain should be managed with suitable analgesia and in some cases, corticosteroids. Some patients may require referral e.g. if complications are evident, if there is ocular involvement, if the patient is immunocompromised or pregnant, if the rash is progressive, if symptoms are not adequately controlled.
Reported complications include:
- Skin changes: secondary infection, scarring, changes in pigmentation
- Post-herpetic neuralgia (common in adults, rare in children)
- Ocular complications (when shingles reactivates in the ophthalmic division of the trigeminal nerve –
ulceration with scarring, keratitis, scleritis, retinal inammation, permanent visual loss)
- Ramsay Hunt syndrome (lesions in the ear, facial paralysis, and associated hearing and vestibular symptoms)
- Rarer – encephalitis, myelitis, retinitis, and hemiparesis.