Varicella Zoster Virus

Snapshot

A 60-year-old man presents to an urgent care clinic for a rash on his right arm. He reports that this rash suddenly occurred about 1 day ago. He has been in 10/10 pain from this rash. He reports that he had chickenpox during his childhood and that his physician had recommended that he receive a shingles vaccine; however, he had not had a chance to do so. He has not been sleeping well, as he is currently going through a divorce. On physical exam, there is a vesicular rash in a dermatomal distribution on his right upper arm. He is sent home with the appropriate treatment.

Introduction

Classification
- varicella-zoster virus (VZV)
  - an enveloped, linear, double-stranded DNA virus
  - also known as human herpesvirus-3
  - transmitted via
    - respiratory secretions
    - direct contact with skin lesions
  - causes chickenpox, herpes zoster (shingles), encephalitis, meningitis, and pneumonia
Epidemiology
- demographics
  - herpes zoster in elderly population
  - chicken pox in children
  - encephalitis and pneumonia in the immunocompromised
  - men > women
- risk factors
  - immunosuppression
  - advanced age
  - previous infection with VZV
Pathogenesis
- the virus infects T-cells
- the virus is often latent in the dorsal root ganglia or trigeminal ganglia
- reactivation of the latent virus causes herpes zoster
  - often precipitated by immunocompromise or stress
Prevention
- herpes zoster
  - recombinant vaccine
    - adults > 50 years of age
  - live vaccine
    - adults > 60 years of age
- chickenpox
  - live vaccine
    - adults and children 1 year or older
Prognosis
- complete healing may take more > 1 month
chickenpox is often self-resolving in children

Presentation

Herpes zoster
- painful unilateral vesicular/pustular skin eruption along a single dermatome
  - does not cross midline
- preceded by prodrome of itchiness or tingling at the site
- may involve the eye
  - herpes zoster opthalmicus
  - distribution of cranial nerve V
- may involve the ear
  - Ramsay-Hunt syndrome or herpes zoster oticus
  - distribution of cranial nerve VII
Chicken pox
- asynchronous vesicular rash
  - very itchy but not painful
  - starts on the head and trunk and spreads to the extremities
  - eventually develops a crust
fever and malaise

Studies

Labs
- Tzanck smear
  - positive if multinucleated giant cells are seen
- polymerase chain reaction
- direct fluorescent antibody staining
Making the diagnosis
- most cases are clinically diagnosed
in atypical cases, laboratory examination may be useful

Differential

Herpes simplex virus
- distinguishing factor
  - typically does not present in a dermatomal fashion
Contact dermatitis
- distinguishing factor
typically is more itchy than painful

Treatment

Management approach
- for herpes zoster, antivirals are first-line therapy
- for chickenpox, treatment is centered around symptomatic relief
Conservative
- soothing creams
  - indication
    - immunocompetent patients with chickenpox
Medical
- oral antivirals
  - indications
    - all patients with shingles
    - immunocompromised patients with chickenpox
  - drugs
    - valacyclovir
    - famciclovir
    - acyclovir
- intravenous antivirals
  - indication
    - patients with visceral or central nervous system disease
  - drugs
    - acyclovir
- analgesics
  - indication
    - all patients
  - drugs
do not give aspirin for risk of Reye syndrome

Complications

Disseminated disease
- in immunocompromised patients
- often involves the viscera
Post-herpetic neuralgia
- incidence
  - very common
Fetal complications
- blindness
- scarring
- limb hypoplasia
Vision loss or keratitis
- from herpes zoster opthalmicus