2.1.1 Varicella and Herpes Zoster

1E90 

Chickenpox; shingles.

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

Chickenpox is a highly contagious disease (by respiratory or direct contact). Usually affects children between 2 and 10 years of age. Endemic outbreaks in spring and autumn. The incubation period for varicella is between 10-21 days and it is highly contagious, via direct skin contact, or contact with aerosolized particles from the vesicles or respiratory secretions. It is a highly prevalent disease (90% of adults have suffered) and gives permanent immunity.

The incidence of herpes zoster ranges between 1.3 and 4 cases per 1000 individuals / year. More than two thirds of cases occur in individuals over 50 years. 10% of cases of shingles occur in individuals with risk factors (cancer, previous trauma, etc.). Its incidence in immunosuppressed subjects is much higher than the general population.

None. 

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.

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.  

According to dermatome. 

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. 

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

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. 

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.

Usually clinical. 

• 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 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.

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