Varicella and Herpes Zoster

ICD-11

1E90

Synonyms

Chickenpox; shingles.

Definition

Varicella-zoster virus (VZV) causes a primary infection usually in childhood (varicella, chickenpox) and may later reactivate in a nerve (herpes zoster, shingles).

Aetiology & Pathogenesis

None.

Signs & Symptoms

Varicella: Incubation period: 1-2 weeks, highly contagious. Clinical features: papulo-vesiculo-pustular exanthem with lesions in varying stages of development.

Herpes zoster: Pathogenesis: viruses persist in the spinal and cranial ganglia (Gasserian ganglion, geniculate ganglion). Exacerbating factors: immunosuppression, trauma, sunlight, severe illnesses.

Clinical features: segmental lesion not crossing the midline with burning, pain, erythema, blisters, necrosis, scars, post-herpetic neuralgia. Herpes zoster haemorrhagicus, gangrenosus- more severe forms; generalised- widespread, resembles varicella with aberrant blisters.

Localisation

Varicella: head and mouth (gums) are often involved but palms and soles are usually spared.

Zoster: in affected dermatome.

Variants: Ophthalmic herpes zoster: 1st trigeminal branch (V1 nerve) sometimes with nasociliary branch; be aware of need for urgent opthalmology review, keratitis. Herpes zoster 2nd or 3rd trigeminal branch. Aural herpes zoster (VIIIth nerve); acoustic nerve and potential facial paralysis.

Classification

According to dermatome.

Laboratory & other workups

Only required if severe involvement or other relevant clinical question. Viral swabs may confirm the diagnosis days later. Immediate confirmation when required via Tzanck smear, PCR of vesicle fluid or antigen test.

Dermatopathology

Not usually required. Intraepithelial blisters and destruction of sebaceous glands are indistinguishable from other viral infections.

Course

Usually a self-limiting disease. Varicella is commonly mild in young children but may be disseminated and severe in adults (especially in pregnancy), rarely leading to multi-organ failure.

Complications

Varicella: fever, malaise, pneumonia, scarring -especially when lesions display secondary infection. Fetal malformations may occur after infection in the 1st trimester; neonatal varicella when infection occurs in the 3rd trimester.

Herpes zoster: dissemination, superadded infection, keratitis and postherpetic neuralgia.

Diagnosis

Usually clinical.

Differential diagnosis

Varicella: insect bites, Coxsackie virus infection, generalized herpes zoster, eczema herpeticum, and other viral exanthems.
Herpes zoster: insect bites; herpes simplex; pain from other causes.

Prevention & Therapy

Prevention of herpes zoster reactivation: immunization.

Topical: antiseptics (e.g. chlorhexidine 1% lotion).

Systemic: antiviral agents (e.g. aciclovir). Indications for systemic treatment: patients> 50 years, disease present less than 3 days, tendency towards generalization, eye involvement (1st branch of trigeminal nerve), immunodeficiency. Analgesics as required (NSAIDs, but acetyl salicylic acid contraindicated re Reyes syndrome) and, in special cases, corticosteroids.

Special

Ask about contacts of the index patient (pregnant individuals, children, immunocompromised).

2.1.1 Varicella and Herpes Zoster