AKT · Infections/Viral infectionslow yield

Varicella zoster (chickenpox & shingles)

Varicella-zoster virus — primary infection (chickenpox) then latency → reactivation (shingles)

Overview

Primary VZV infection is chickenpox (varicella) — a vesicular rash in crops; the virus then lies latent in dorsal-root ganglia and can reactivate as shingles (herpes zoster) — a painful dermatomal vesicular rash. The high-yield concerns are chickenpox in pregnancy/the immunocompromised/neonates, the contagious period, ophthalmic and Ramsay Hunt zoster, and post-herpetic neuralgia. Aciclovir is used for at-risk/zoster; VZIG protects vulnerable exposed contacts.

Recognise

Chickenpox: fever then an itchy vesicular rash in CROPS (macule→papule→vesicle→crust) at different stages; contagious from ~2 days before the rash until lesions crust
Shingles: prodromal pain then a painful vesicular rash in a single DERMATOME (does not cross the midline); post-herpetic neuralgia is the common sequela
Danger groups: pregnancy (maternal pneumonia/varicella; congenital varicella; neonatal varicella), immunocompromised (disseminated/severe), neonates

Red flags

Chickenpox in pregnancy, immunocompromised, or a neonate → severe/disseminated → aciclovir; exposed susceptible pregnant/immunocompromised contacts → VZIG
Herpes zoster OPHTHALMICUS (V1, Hutchinson's sign — nose-tip lesion) → ophthalmology; Ramsay Hunt (facial palsy + ear vesicles) → prompt treatment

Differentials & how to tell them apart

Other vesicular rasheshand-foot-and-mouth, disseminated HSV, eczema herpeticum — distribution/PCR

Other causes of dermatomal painpre-eruptive zoster can mimic cardiac/abdominal pain until the rash appears

Disseminated zosterimmunocompromised — multidermatomal/widespread → systemic aciclovir

Investigations

Usually clinical; PCR of vesicle fluid if uncertain/severe; VZV serology for immunity status in exposed pregnant women; assess for complications (pneumonia, encephalitis, secondary bacterial infection, ophthalmic involvement).

Management

Supportive for healthy chickenpox; aciclovir for shingles/at-risk varicella; VZIG for vulnerable contacts

1Recognise chickenpox (vesicles in crops at different stages) vs shingles (painful single dermatome). Healthy children → supportive care (avoid NSAIDs); keep off school until lesions crust.Gate: Chickenpox in pregnancy/immunocompromised/neonates is dangerous → aciclovir, and give VZIG to susceptible exposed vulnerable contacts; herpes zoster ophthalmicus (Hutchinson's sign) → ophthalmology.
2Aciclovir for shingles (older/ophthalmic/within 72 h) and at-risk varicella; manage post-herpetic neuralgia and ophthalmic/Ramsay Hunt zoster; shingles vaccine for prevention. (Shingles also carded on dermatology.)

Healthy child with chickenpox: supportive (calamine, antihistamine, antipyretic — paracetamol not ibuprofen) — avoid NSAIDs (necrotising soft-tissue infection risk); keep off school until crusted

Aciclovir for at-risk/severe chickenpox and for shingles — oral aciclovir for shingles (esp. >50/ophthalmic/within 72 h) and for adults/at-risk varicella; IV for severe/immunocompromised/disseminated

VZIG (or aciclovir) for vulnerable exposed contacts — susceptible pregnant women, immunocompromised, neonates exposed to chickenpox

Manage complications + zoster vaccine (prevention) — post-herpetic neuralgia (amitriptyline/gabapentin), ophthalmic zoster (ophthalmology); shingles vaccine for older adults

Key points

VZV: chickenpox = vesicles in CROPS at different stages (contagious until crusted; avoid NSAIDs); shingles = painful single DERMATOME. Danger groups: pregnancy/immunocompromised/neonates → aciclovir + VZIG for vulnerable exposed contacts. Zoster ophthalmicus (Hutchinson's sign) → ophthalmology; post-herpetic neuralgia common.

Monitor & prognosis

Lesion crusting/contagion, complications (pneumonia/encephalitis/ophthalmic), post-herpetic neuralgia.

Self-limiting in healthy children; severe in at-risk groups; shingles often leaves post-herpetic neuralgia.

Source: NICE CKS (chickenpox/shingles); cross-ref dermatology, O&G (pregnancy), ophthalmology (HZO)