Varicella-Zoster Virus - VZV

Varicella-Zoster Virus - VZV

 

Varicella-zoster virus (VZV) is the cause of chickenpox in children and shingles in adults.

Epidemiology

  • Incidence – estimated 1 million new cases annually in the U.S.
  • Age
    • Varicella – children
    • Herpes zoster – >60 years
  • Gender – equal distribution

Risk Factors

  • For non-immune individuals, direct contact with large-particle droplets
  • Risk factors include immune deficiency conditions, psychological stress and localized physical trauma

Organism

  • DNA virus
  • Member of the Herpesviridae family
  • Adult infection usually the result of reactivated latent infection of sensory ganglia

Clinical Presentation

  • Varicella
    • Fever and generalized exanthem
  • Herpes zoster
    • Characterized by:
      • Skin eruption
        • Unilateral maculopapular lesions followed by vesicular eruptions with dermatomal distribution
      • Facial nerve (7th cranial nerve) involvement (Ramsey-Hunt syndrome)
      • Pain from inflammation of sensory nerve ganglia
      • May mimic other serious medical conditions such as myocardial infarction, appendicitis, acute cholecystitis, renal colic, pulmonary embolism or glaucoma
      • Lesson common manifestations include pneumonitis, acute retinal necrosis, myelitis, vasculopathy, hepatitis and meningoencephalitis
      • Complications
        • Postherpetic neuralgia
        • Secondary skin infection from Streptococcus pyogenes or S. aureas
      • Congenital infection  – congenital VZV transmission may cause severe disseminated neonatal infection with:
        • Pneumonia
        • Skin lesions
        • Hemorrhages
        • Death 

Diagnosis

  • Based on typical appearance of skin lesions
    • Chickenpox – skin lesions are in different stages of development (papule, vesicle, pustule, umbilication, and crusting)
    • Shingles – vesicles along a dermatonal distribution
  • In VZV-CNS syndromes where viral recovery from CSF is poor, PCR is recommended

Differential Diagnosis

  • Cutaneous (chickenpox) – HSV, smallpox, rickettsial pox and bullous impetigo
  • Cutaneous (Zoster) – HSV, contact dermatitis, poison ivy, poison oak and bullous impetigo
  • Viral encephalitis and meningitis

Treatment

  • Early treatment of zoster accelerates resolution and perhaps lessens post-herpetic pain

Prevention

  • Childhood vaccination preventive for VZV in most cases
  • Universal vaccination has decreased outbreaks and severity of secondary complications
  • New vaccine recently approved for adults >60 years to prevent herpes zoster
    • Vaccine shown to reduce the incidence of PHN by 66.5%

See Also