Varicella zoster

Chickenpox is caused by primary infection with varicella zoster virus (VZV and is also known as human herpes virus 3 or HHV3). Shingles is reactivation of dormant virus in dorsal root ganglion

Chickenpox infection

• Highly infectious
• Spread via droplets primarily via the respiratory route
• Can be caught from someone with shingles
• Infectivity = 4 days before rash, until 5 days after the rash first appeared*
• incubation period = 10-21 days

Clinical features

• Typically mild & self limiting
• Symptoms tend to be more severe in older children/adults
• Fever initially
• Itchy, rash starting on head/trunk before spreading. Initially macular then papular then vesicular
• Systemic upset is usually mild

Management

• Typically supportive
• keep cool, trim nails
• Calamine lotion
• School exclusion: People with chickenpox should avoid contact with other people for at least 5 days from the onset of the rash and until all blisters have crusted over
• Immunocompromised patients and newborns with peripartum exposure should receive varicella zoster immunoglobulin (VZIG). If chickenpox develops then IV aciclovir should be considered

Complications

Common:

• Secondary bacterial infection of the lesions.

Rare:

• pneumonia
• encephalitis (cerebellar involvement may be seen)
• disseminated haemorrhagic chickenpox
• arthritis, nephritis and pancreatitis may very rarely be seen

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Shingles

Following primary infection with varicella zoster (Chickenpox) the virus remains dormant in the geniculate, trigeminal or dorsal root ganglia of the nervous system. Reactivation of the virus, often in response to a decline in immune function, results in the virus travelling down the affected nerve and producing shingles.

Clinically shingles typically presents with signs of nerve irritation (patients may describe this as burning, itching or paraesthesia) for several days before eruption of the shingles rash within the dermatomal distribution of the affected nerve. The patient may feel unwell with malaise, myalgia, headache and fever prior to the rash presenting.

The rash typically appears as erythema with small vesicles. New vesicle clusters may keep forming for up to 7 days. Vesicles will usually dry out and crust over within 10 days of their appearance. Resolution usually takes 2-3 weeks.



Management
The majority of patients with shingles are not seriously ill but the clinician should admit or seek urgent specialist advise for patients with shingles who have the following:

• Suspected serious complications such as meningitis, encephalitis, or myelitis
• Ophthalmic shingles
• Patient is severely immunocompromised
• Immunocompromised patient who is systemically unwell or severe/widespread rash
• New vesicles are forming after 7 days of antiviral treatment, or healing is delayed.
• Pregnant or breastfeeding woman

For most patients management will consist of:

• Keep vesicles covered & dry to prevent secondary bacterial infection
• Advise people may catch chickenpox from exposure to vesicle fluid if not already immune
• Pain relief: initially paracetamol alone or in combination with codeine or NSAID. Neuropathic painkillers such as amitriptyline should be considered if above ineffective or pain severe.
• Consider antiviral treatment (see box below) with aciclovir, valaciclovir or famciclovir
• Steroids may be used in the first 2 weeks following rash onset in immunocompetent adults with localized shingles if pain is severe, but only in combination with antiviral treatment.