Varicella

Basics

Description

  • Varicella is in the family of herpesviruses
  • Also called varicella-zoster virus (VZV)
  • Causes two distinct clinical diseases: varicella (chickenpox) and herpes zoster (shingles)
  • Primary VZV is commonly known as chicken pox, which is a diffuse vesicular rash of varicella
  • Latent VZV can recur as shingles (herpes zoster), which is usually a localized skin reaction
  • Most common in late winter and early spring
  • Vaccine developed in 1995 has reduced incidence by 85%
  • Adults have a 15 times greater risk for death from varicella as compared to children

Etiology

  • Double-stranded DNA virus:
    • Localized replication after entry into the body in nerve ganglia and lymph nodes
    • Primary viremic phase follows
    • Incubation is 10–21 d
    • Patients are infective from 48 hr before the rash presents until skin vesicles are crusted over
    • May present as herpes zoster or shingles decades after primary infection
    • Transmission is by aerosolized droplets from infected host to the respiratory mucosa of susceptible patient
    • Also transmitted by direct contact with skin lesions
    • Reinfection was thought to be rare, but has been found to be relatively common

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