Microbiology · Human herpesviruses
Varicella-zoster virus !
- Virus
- Enveloped
- Contact
- Airborne
- Exam priority: high
The virus of childhood chickenpox that, years later, can reactivate as shingles (herpes zoster) in one dermatome.
Updated 2026-11-01
Also called: VZV, chickenpox virus, shingles
At a glance
- Shape
- Icosahedral with tegument and envelope
- Genome
- Linear double-stranded DNA
- Envelope
- Enveloped
- Family
- Herpesviridae (alphaherpesvirus)
- Size
- About 150 to 200 nm
Morphology
- Typical herpesvirus structure
- Multinucleated giant cells at the base of vesicles, as with HSV
Transmission
- Aerosols from skin lesions and probably respiratory secretions
- Direct contact with vesicle fluid
- Contagious from 1 to 2 days before the rash until all lesions have crusted
- Zoster can cause chickenpox in people without immunity
Reservoir: Humans
Isolation precautions
What the care team adds to standard precautions.
- Contact
- Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.
- Airborne
- N95 respirator and a negative-pressure room.
Virulence factors
- Latency in sensory dorsal root and cranial nerve ganglia
- Reactivates when cell-mediated immunity falls with age or immunosuppression
- Highly contagious: most susceptible household contacts become infected
Diseases it causes
- Varicella (chickenpox) Varicella (chickenpox) →
- Herpes zoster and postherpetic neuralgia Herpes zoster (shingles) →
- Varicella pneumonia, encephalitis, congenital varicella syndrome and herpes zoster ophthalmicus
Clinical picture
- Chickenpox: itchy rash moving from macule to papule, vesicle and crust, with lesions at different stages at once
- Zoster: pain and vesicles in one or two neighbouring dermatomes, not crossing the midline, often on the chest or face
- Complications: bacterial skin infection in children, pneumonia in adults, severe disease in pregnancy and immunosuppression
- Zoster ophthalmicus (V1 branch) can threaten sight; Ramsay Hunt syndrome affects the facial nerve and ear
Diagnosis
- Clinical diagnosis in most cases
- PCR of lesion fluid or crust to confirm
- IgG serology to check immunity in staff or pregnant women
Treatment
Acyclovir or valacyclovir, used mainly for adults, immunocompromised patients, zoster and severe cases, ideally early. Foscarnet for resistance. Aspirin is avoided in children because of the risk of Reye syndrome.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Live attenuated varicella vaccine
- Recombinant zoster vaccine for older and immunocompromised adults
- Varicella-zoster immune globulin after exposure for high-risk people without immunity
- Airborne (negative-pressure room) and contact precautions until all lesions have crusted; only immune staff care for the patient
Vaccine: The varicella vaccine (live attenuated) is in Colombia's PAI for early childhood, with a booster. The recombinant zoster vaccine is not part of the free schedule.
Test yourself
Think of the answer, then tap the question to see it.
Which transmission-based precautions does a child admitted with chickenpox need?
Standard plus airborne (negative-pressure room) and contact precautions, until all lesions are dry and crusted.
How does the chickenpox rash differ from the smallpox rash?
In chickenpox lesions of different stages coexist; in smallpox all lesions in one area are at the same stage.
Why does varicella-zoster virus reactivate in older adults?
Because the specific cell-mediated immunity that keeps it latent in the sensory ganglia declines with age.
Related
Related conditions
← Back to the group: Human herpesviruses
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Clinical Overview of Chickenpox (Varicella) (CDC, 2024); Clinical Overview of Shingles (Herpes Zoster) (CDC, 2024); Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions (CDC, 2024).
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Representative model, for educational purposes only.