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Updated: Mar 20 2022

Varicella Zoster Virus

Images
https://upload.medbullets.com/topic/104056/images/herpesviruses-15.jpg
https://upload.medbullets.com/topic/104056/images/varicella.jpg
https://upload.medbullets.com/topic/104056/images/chickenpox_adult_back.jpg
  • 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
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