What is shingles (herpes zoster)?

What is Shingles?

Shingles (herpes zoster) is a painful, blistering rash caused by reactivation of the varicella-zoster virus (VZV) that remains dormant in nerve ganglia after an initial chickenpox infection. 1

Pathophysiology

After primary varicella infection (chickenpox), VZV remains latent in the dorsal root ganglia or sensory ganglia of cranial nerves. When cellular immunity fails to control this dormant virus—typically in adults, elderly, or immunocompromised individuals—the virus reactivates and travels down the nerve to the skin, producing the characteristic manifestations of herpes zoster. 1, 2

Clinical Presentation

The disease manifests as:

• Painful, vesicular (blistering) rash with a dermatomal distribution (following a single nerve pathway)
• Unilateral presentation affecting one side of the body
• Typically involves a single strip of skin corresponding to the affected nerve
• May affect nerves in the head, face, or body 3, 4

Important caveat: While pain is the hallmark symptom, atypical painless presentations can occur, particularly in elderly patients, which may delay diagnosis. 4

Epidemiology and Risk

• Lifetime risk: 20-30% in the general population 1
• Risk increases to 50% in those aged >85 years 1
• Incidence: 1.2 to 4.8 cases per 1,000 person-years in Europe/US; 4.97 per 1,000 person-years in Taiwan 1
• Women have higher risk than men 1, 5

High-Risk Populations

Significantly elevated risk occurs in:

• Elderly patients (age ≥50 years)
• Immunocompromised individuals including those with:
  • HIV/AIDS (RR 1.53)
  • Cancer/lymphoma/leukemia (RR 1.91)
  • Diabetes mellitus (RR 1.52)
  • Systemic lupus erythematosus (RR 2.08-2.12)
  • Rheumatoid arthritis (RR 1.51)
  • Inflammatory bowel disease
  • Organ transplant recipients
  • Those on immunosuppressive therapy 1, 6

Complications

Herpes zoster can lead to potentially debilitating complications that significantly impact quality of life:

• Postherpetic neuralgia (PHN): Most common complication occurring in 10-18% of cases—persistent dermatomal pain lasting >90 days after symptom onset 3
• Herpes zoster ophthalmicus: Can lead to vision loss
• Bacterial superinfections
• Cranial and peripheral nerve palsies
• Visceral involvement
• Neurological complications 1, 3, 2

Prevention

The most effective strategy to prevent herpes zoster and its complications is vaccination. 1 Two vaccines are available:

1. Recombinant zoster vaccine (RZV/Shingrix) - preferred, inactivated vaccine

   • Two-dose series
   • Recommended for adults ≥50 years
   • Safe for immunocompromised adults ≥18 years 1, 6

2. Zoster vaccine live (ZVL/Zostavax) - live attenuated vaccine

   • Single dose
   • Contraindicated in immunocompromised patients due to risk of disease from live virus 1

The recombinant vaccine demonstrates high efficacy and robust immune responses across various immunocompromising conditions with an acceptable safety profile. 6