Makindo Medical Notes

Related Subjects: |Herpes Varicella-Zoster (Shingles) Infection |Chickenpox Varicella Infection |Varicella Cerebral Vasculopathy |Herpes Viruses |Herpes Zoster Ophthalmicus (HZO) Shingles

About 33% of the general population are colonised with Staphylococcus aureus (including MRSA) at any one time. By contrast, Varicella-Zoster Virus (VZV) infects almost everyone by adulthood, causing chickenpox as a primary infection and shingles when reactivated.

About

• Varicella-zoster virus (VZV) causes chickenpox in primary infection and shingles upon reactivation from dorsal root ganglia.
• Chickenpox is highly contagious, usually mild in children under 10, with seasonal peaks January–April in the UK.
• Adults experience more severe illness than children; complications are far more likely.
• Shingles only occurs in those who have had chickenpox; however, exposure to shingles can cause chickenpox in non-immune individuals.

Transmission

• Highly contagious: ~90% transmission among susceptible household contacts.
• Incubation: 10–21 days. Infectious from 1–2 days before rash until all vesicles have crusted.
• Spread: respiratory droplets, direct vesicle contact, or contaminated clothing/linen.

Clinical Presentation

• Prodrome: fever, malaise, headache, myalgia.
• Classic rash: intensely itchy vesicles on erythematous base (“dew drop on a rose petal”), starting on trunk then face/scalp, sparing palms/soles.
• Lesions appear in crops at different stages (papules, vesicles, crusts).
• Immunocompromised patients may have more severe and prolonged disease.

Complications

• Infants & adults: higher risk of severe disease.
• Bacterial superinfection of lesions, especially in children <5.
• Neurological: cerebellitis, encephalitis, meningitis.
• Pulmonary: varicella pneumonia, particularly in adults and smokers.
• Other rare: hepatitis, myocarditis, glomerulonephritis.

Varicella in Pregnancy

• Maternal infection: risk of pneumonia (10–14%), encephalitis, hepatitis. Mortality ~1%.
• Fetal Varicella Syndrome (FVS): if infection between 3–28 weeks → dermatomal scars, eye defects, limb hypoplasia, CNS abnormalities.
• Neonatal varicella: if maternal rash develops 7 days before to 7 days after delivery → severe disseminated infection risk.

Investigations

• Clinical diagnosis usually sufficient.
• Vesicle fluid microscopy (Tzanck smear) or PCR if uncertain.
• Serology can confirm immunity (VZV IgG).

Management

• Symptomatic: paracetamol for fever (avoid aspirin in children due to Reye’s syndrome); antihistamines, calamine or cooling gels for itch.
• Isolation until lesions crusted over.
• High-risk groups (immunocompromised, neonates, pregnant women): consider VZIG for post-exposure prophylaxis or Aciclovir treatment.

Chickenpox in Pregnancy

• Pregnant women with suspected chickenpox should seek urgent GP/maternity advice and avoid contact with susceptible individuals.
• Hospital assessment if respiratory or systemic symptoms.
• Isolation in hospital settings.
• Oral Aciclovir: 800 mg five times daily × 7 days if within 24 h of rash onset and ≥20 weeks’ gestation.
• IV Aciclovir: for severe disease (e.g. pneumonia, encephalitis).

References

• Royal Berkshire NHS – Varicella in Pregnancy Guidelines

Clinical Pearl: Chickenpox is usually benign in children, but serious in adults and pregnancy. Always ask about pregnancy status and immune history when a woman of childbearing age presents with rash or exposure.