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Infectious Diseases
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EMERGENCY

Varicella Zoster Virus (Chickenpox & Shingles)

High EvidenceUpdated: 2025-12-24

On This Page

Red Flags

  • Hutchinson's Sign (vesicles on tip of nose - ophthalmology emergency)
  • Varicella Pneumonitis (cough/dyspnoea in adults/pregnant)
  • Ramsay Hunt Syndrome (Facial palsy + ear pain/vesicles)
  • Meningoencephalitis (Drowsiness/Seizures)
  • Disseminated Zoster (immunocompromised)
Overview

Varicella Zoster Virus (Chickenpox & Shingles)

1. Clinical Overview

Summary

Varicella Zoster Virus (VZV / HHV-3) causes two distinct clinical syndromes. Varicella (Chickenpox) is the primary infection, usually in childhood, causing a widespread vesicular exanthem. Herpes Zoster (Shingles) is the reactivation of latent virus from dorsal root ganglia, causing a painful, unilateral dermatomal rash. While chickenpox is generally benign in children, it can be severe in adults, pregnant women (pneumonitis), and the immunocompromised. Shingles is a disease of aging/immunosuppression, with Post-Herpetic Neuralgia (PHN) being the major debilitating complication. [1,2]

Key Facts

  • Infectivity: Highly contagious (R₀ 10-12). Airborne and contact spread. Infectious from 48h before rash until all lesions crusted.
  • Chickenpox Rash: "Starry sky" appearance (macules, papules, pustules, and crusts all present simultaneously).
  • Shingles Rash: Strictly dermatomal. Does not cross midline.
  • Severe Complications: Varicella Pneumonitis (high mortality in adults), Encephalitis, Necrotising Fasciitis (secondary bacterial infection).
  • Ophthalmic Zoster: Involvement of V1 (trigeminal) nerve requires urgent ophthalmology review to prevent blindness.

Clinical Pearls

Hutchinson's Sign: Vesicles on the tip or side of the nose indicate nasociliary nerve involvement (branch of V1). This strongly predicts ocular involvement (uveitis/keratitis). Refer to Eye Casualty.

Ramsay Hunt Syndrome: Herpes Zoster Oticus. Triad of: 1) Ipsilateral facial palsy (LMN), 2) Ear pain, 3) Vesicles in auditory canal/auricle. Prognosis for facial nerve recovery is worse than Bell's palsy.

Pregnancy Exposure: If a non-immune pregnant woman is exposed to chickenpox, she needs VZIG (Varicella Zoster Immunoglobulin) or Aciclovir prophylaxis immediately to prevent maternal pneumonitis and Fetal Varicella Syndrome.

Shingles Infection Risk: You cannot catch Shingles from someone with Shingles. You generally catch Chickenpox from someone with Shingles (if you are naive).

2. Epidemiology

Varicella (Chickenpox)

  • Age: >90% cases in children less than 10 years (in non-vaccinated populations).
  • Seasonality: Winter/Spring peak.
  • Prevalence: Near universal by adulthood in temperate climates.

Herpes Zoster (Shingles)

  • Risk: Lifetime risk ~30%.
  • Age: Incidence increases sharply after age 50 (immunosenescence).
  • Recurrence: Occurs in ~5% of patients.

Risk Factors for Severe Disease

  • Adults: Pneumonia risk 25x higher than children.
  • Pregnancy: High risk of pneumonitis.
  • Immunocompromised: Disseminated disease.
  • Smokers: Increased pneumonia risk.
3. Pathophysiology

Primary Infection (Varicella)

  1. Entry: Inhalation of droplets or contact with fluid.
  2. Replication: In regional lymph nodes (Day 2-4).
  3. Viraemia: Primary viraemia (Day 4-6) → Liver/Spleen. Secondary viraemia (Day 10-14) → Skin (Rash).
  4. Latency: Virus travels up sensory nerves to Dorsal Root Ganglia (DRG) and becomes latent.

Reactivation (Zoster)

  1. Trigger: Decline in T-cell immunity (Age, Stress, HIV, Chemo).
  2. Reactivation: Virus travels down the sensory nerve axon to the skin.
  3. Dermatome: inflammation and vesiculation restricted to the dermatome supplied by that nerve.
  4. Pain: Neuritis causes severe neuropathic pain (often precedes rash).
4. Clinical Presentation

A. Chickenpox (Varicella)

B. Shingles (Herpes Zoster)

Red Flags

  1. Respiratory symptoms: Varicella Pneumonitis (dyspnoea, cough, haemoptysis).
  2. Confusion/Drowsiness: Encephalitis.
  3. Visual symptoms: Herpes Zoster Ophthalmicus.
  4. Severe secondary bacterial infection: Sepsis/Necrotising Fasciitis (Group A Strep).
Prodrome
Fever, malaise, headache (1-2 days before rash).
Rash
Starts on head/trunk → Spreads to limbs (Centripetal). Itchy (pruritic). Evolution: Macule → Papule → Fluid-filled Vesicle ("Dew drop on rose petal") → Pustule → Crust. Polymorphic: Lesions in all different stages seen at once.
Mucosal
Ulcers in mouth, conjunctiva, genitals.
5. Clinical Examination

Chickenpox

  • Widespread vesicles.
  • Check chest (pneumonitis).
  • Check neurological status (cerebellar ataxia - a common benign complication in kids).

Shingles

  • Define dermatome (e.g., T4 nipple line, V1 forehead).
  • Hutchinson's Sign: Nose tip vesicles.
  • Eye: Red eye, photophobia (Uveitis).
  • Ear: Vesicles in conchal bowl (Ramsay Hunt).
6. Investigations

Diagnosis

  • Usually Clinical. Testing rarely needed for classic presentation.
  • PCR: Swab of vesicle fluid (Gold standard if diagnosis uncertain). more sensitive than culture.
  • Tzanck Smear: Historical (multinucleated giant cells).

Serology (IgG)

  • Used to determine immune status in exposed pregnant women or healthcare workers.

Systemic Assessment (Severe Cases)

  • CXR: Diffuse interstitial nodules (Pneumonitis).
  • LP: If encephalitis suspected (Lymphocytic pleocytosis, PCR).
7. Management

Management Algorithm

           VZV PRESENTATION
                  ↓
      ┌───────────┴───────────┐
      ↓                       ↓
  CHICKENPOX              SHINGLES
      ↓                       ↓
- RISK ASSESSMENT       - RISK ASSESSMENT
 (Age, Pregnancy,        (Eye involved? Age?
  Immune status)          Immunocompromised?)
      ↓                       ↓
┌─────────────┐         ┌────────────────────┐
│CHILD:       │         │UNCOMPLICATED:      │
│Supportive   │         │Oral Aciclovir 800mg│
│(Calamine)   │         │5x/day for 7 days   │
│             │         │(Start less than 72 hours)   │
│ADULT:       │         │                    │
│Aciclovir    │         │OPHTHALMIC:         │
│(if less than 24h)    │         │+Urgent Eye Referral│
└─────────────┘         └────────────────────┘

1. Management of Chickenpox

  • Children: Minimal intervention. Calamine lotion, Antihistamines (Chlorphenamine). Avoid Ibuprofen (link to necrotising fasciitis). Paracetamol ok.

  • Adults (>14 years): Oral Aciclovir 800mg 5 times/day for 7 days. (Reduces duration/severity if started less than 24h).

  • Severe/Immunocompromised: IV Aciclovir.

  • School Exclusion: Until all vesicles have crusted over (usually 5 days from onset).

2. Management of Shingles

  • Antivirals: Aciclovir (800mg 5x/day), Valaciclovir (1g TDS), or Famciclovir.
    • Start within 72 hours of rash onset to reduce severity and risk of PHN.
    • Start >72h if new vesicles still forming or ophthalmic zoster.
  • Analgesia:
    • Acute: Paracetamol, NSAIDs, weak opioids.
    • Neuropathic: Amitriptyline, Gabapentin, Pregabalin (for PHN).
  • Steroids: Oral prednisolone sometimes added for Ramsay Hunt or severe pain (controversial evidence).

3. Pregnancy Exposure

Non-immune pregnant woman significantly exposed to VZV.

  • less than 20 weeks: Risk of Fetal Varicella Syndrome.
  • Near term: Risk of severe neonatal varicella.
  • Management:
    • Check IgG.
    • If negative: Give VZIG (Varicella Zoster Immunoglobulin) or Aciclovir Prophylaxis (days 7-14 post exposure).
8. Complications

Chickenpox Complications

  1. Secondary Bacterial Infection: Staph/Strep infection of scratch marks including Necrotising Fasciitis.
  2. Varicella Pneumonitis: 10-20% of adults. High mortality (10-30%) if untreated.
  3. Cerebellar Ataxia: Common childhood complication (1/4000). Self-limiting gait disturbance ~1 week after rash.
  4. Encephalitis: Rare, serious.
  5. Fetal Varicella Syndrome: Skin scarring, limb hypoplasia, microcephaly (risk 2% if infection less than 20 weeks).

Shingles Complications

  1. Post-Herpetic Neuralgia (PHN): Pain persisting >3 or >6 months after rash.
    • Risk increases with age (>60).
    • Can be severe and suicidal.
  2. Herpes Zoster Ophthalmicus (HZO): Keratitis, Uveitis, Acute Retinal Necrosis.
  3. Ramsay Hunt Syndrome: Facial nerve palsy.
  4. Disseminated Zoster: Rash crossing dermatomes/midline. Suggests HIV/Lymphoma.
9. Prognosis and Outcomes

Post-Herpetic Neuralgia

  • Affects 20% of Shingles patients >50 years.
  • Can last years.
  • Treatment: Topical lidocaine, Capsaicin, Amitriptyline, Gabapentinoids.

Vaccines

  1. Varicella Vaccine: Live attenuated. Routine in US/Aus, selective in UK (healthcare workers/contacts).
  2. Shingles Vaccine:
    • Zostavax: Live attenuated. (Being replaced).
    • Shingrix: Recombinant subunit (adjuvanted). >90% efficacy. Recommended for over 50s/60s.
10. Evidence and Guidelines

Key Guidelines

GuidelineOrganisationKey Recommendations
Shingles ManagementNICE CKSTreat if >50yrs, or ophthalmic, or immunocompromised.
Varicella in PregnancyRCOG Green-topVZIG/Aciclovir prophylaxis timing.
HZOOphthalmological SocietiesOral antiviral dosing is sufficient; IV rarely needed unless retinal necrosis.

Landmark Studies

1. Shingrix Vaccine Trials (ZOE-50/70)

  • Result: Efficacy >90% against shingles and PHN, sustained for at least 4 years.
  • Impact: Superior to Zostavax (~50%). Now preferred vaccine globally.

2. NSAIDs and Necrotising Fasciitis

  • Observation: Case-control studies link ibuprofen use during chickenpox to severe Group A Strep soft tissue infections.
  • Recommendation: Avoid NSAIDs in chickenpox.
11. Patient and Layperson Explanation

What is the difference between Chickenpox and Shingles?

They are caused by the same virus. You usually catch Chickenpox as a child (lots of itchy spots all over). The virus then goes to sleep in your nerves. Decades later, it wakes up as Shingles (painful rash in one strip of skin).

Can I catch Shingles?

You cannot "catch" shingles from someone. Shingles comes from the virus already inside you. HOWEVER, if you have shingles, the fluid in the blisters contains the virus. If someone who has never had chickenpox touches it, they can catch Chickenpox.

How to manage Chickenpox at home

  • Keep cool (heat makes itching worse).
  • Cut fingernails short to prevent scratching/scarring.
  • Calamine lotion or cooling gels for itch.
  • Paracetamol for fever.
  • DO NOT use Ibuprofen/Nurofen (can cause serious skin infections).

What is Post-Herpetic Neuralgia?

This is pain that stays in the area of shingles long after the rash has healed. It happens because the nerves were damaged. It can feel burning, shooting, or sensitive to touch. Medicines like amitriptyline help calm the nerves.

12. References

Primary Sources

  1. Gershon AA, et al. Varicella zoster virus infection. Nat Rev Dis Primers. 2015;1:15016. PMID: 27188665.
  2. Cohen JI. Herpes Zoster. N Engl J Med. 2013;369:255-263. PMID: 23863052.
  3. NICE CKS. Shingles. https://cks.nice.org.uk/topics/shingles/. Accessed 2025.
  4. RCOG Green-top Guideline No. 13. Chickenpox in Pregnancy. 2015.
13. Examination Focus

Common Exam Questions

  1. Dermatology: "Unilateral vesicular rash on forehead and tip of nose. Action?"
    • Answer: Herpes Zoster Ophthalmicus with Hutchinson's sign. Urgent Ophthalmology referral.
  2. Paediatrics: "Child with chickenpox, high fever, and very red swollen leg. Diagnosis?"
    • Answer: Secondary bacterial cellulitis/Necrotising fasciitis (Group A Strep).
  3. General Practice: "70-year-old with shingles rash for 2 days. Treatment?"
    • Answer: Oral Aciclovir 800mg 5x daily for 7 days.
  4. Neurology: "Ramsay Hunt Syndrome triad?"
    • Answer: Facial palsy, Ear pain, Auricular vesicles.

Viva Points

  • R₀: Chickenpox is one of the most contagious diseases (comparable to Measles).
  • Mechanism of Latency: Virus resides in satellite cells of dorsal root ganglia, evading immune surveillance until T-cell immunity drops.
  • Aspirin in Kids: Avoid due to Reye's syndrome (applies to Varicella and Influenza).

Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.

Last updated: 2025-12-24

At a Glance

EvidenceHigh
Last Updated2025-12-24
Emergency Protocol

Red Flags

  • Hutchinson's Sign (vesicles on tip of nose - ophthalmology emergency)
  • Varicella Pneumonitis (cough/dyspnoea in adults/pregnant)
  • Ramsay Hunt Syndrome (Facial palsy + ear pain/vesicles)
  • Meningoencephalitis (Drowsiness/Seizures)
  • Disseminated Zoster (immunocompromised)

Clinical Pearls

  • **Shingles Infection Risk**: You cannot catch Shingles from someone with Shingles. You generally catch *Chickenpox* from someone with Shingles (if you are naive).

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines