What is the difference between shingles (herpes zoster) and chickenpox (varicella)?

Differences Between Shingles and Chickenpox

Shingles (herpes zoster) and chickenpox (varicella) are both caused by the same virus - varicella zoster virus (VZV) - but they represent different stages of infection and have distinct clinical presentations. 1

Primary Infection vs. Reactivation

• Chickenpox (Varicella):

  • Primary infection with VZV
  • Typically occurs in childhood
  • Results from first-time exposure to the virus
  • Characterized by widespread vesicular rash across the body 1, 2

• Shingles (Herpes Zoster):

  • Reactivation of latent VZV from sensory ganglia
  • Occurs when cellular immune response fails to control latent VZV
  • More common in adults, especially elderly and immunocompromised individuals
  • Lifetime risk of developing shingles is 15-20% 1, 3

Clinical Presentation

Chickenpox (Varicella)

• Rash characteristics:
  • Widespread distribution across the body (trunk, face, extremities)
  • Pruritic macules, papules, vesicles, pustules, and crusts in various stages
  • 250-500 skin lesions typically develop 4
  • Lesions often appear in the mouth, conjunctivae, or other mucosal sites
• Associated symptoms:
  • Fever lasting approximately 5 days
  • Malaise
  • Incubation period of 14-16 days (range: 10-21 days) 4

Shingles (Herpes Zoster)

• Rash characteristics:
  • Unilateral, confined to a single dermatome
  • Painful vesicular cutaneous eruption
  • Follows the distribution of a sensory nerve
  • Vesicles progress to pustules, then to crusts 2, 3
• Associated symptoms:
  • Prodromal pain often precedes rash by several days
  • Burning sensation in affected area
  • Neuralgia (nerve pain) that may persist after rash resolves 5

Complications

Chickenpox (Varicella)

• Generally mild in children with little morbidity
• More severe in adults
• Potential complications:
  • Bacterial superinfection of skin lesions
  • Pneumonia
  • Encephalitis
  • Hepatitis
  • Thrombocytopenia 1, 2

Shingles (Herpes Zoster)

• Primary complication is postherpetic neuralgia (occurs in about 20% of patients)
  • Defined as pain persisting for at least 90 days after acute herpes zoster
• Other complications:
  • Herpes zoster ophthalmicus (when affecting the ophthalmic branch of trigeminal nerve)
  • Bacterial superinfections
  • Cranial and peripheral nerve palsies
  • Scarring and changes in pigmentation 1, 5, 3

Risk Factors

Chickenpox (Varicella)

• Lack of previous VZV infection or vaccination
• Exposure to infected individuals
• Childhood (90% of cases occur in children under 15 years) 4, 1

Shingles (Herpes Zoster)

• Advanced age (incidence increases markedly after 50 years)
• Immunosuppression (20-100 times higher risk)
• Previous varicella infection
• Cellular immune dysfunction
• Stress
• Other infections 4, 1, 3

Prevention and Treatment

Prevention

• Chickenpox: Varivax (live attenuated vaccine) for children
• Shingles: Zostavax (live attenuated) or Shingrix (recombinant subunit) for adults 50+ years 1, 6

Treatment

• Both conditions can be treated with antiviral medications:
  • Acyclovir
  • Valacyclovir
  • Famciclovir 7, 5, 3
• Treatment is most effective when started within 72 hours of rash onset 5

Key Takeaway

The fundamental difference is that chickenpox is the primary infection with VZV that typically occurs in childhood, while shingles is the reactivation of the latent virus that has remained dormant in sensory ganglia since the initial chickenpox infection, usually occurring later in life when immunity wanes.