How is herpes zoster transmitted?

Transmission of Herpes Zoster (Shingles)

Herpes zoster (shingles) is primarily transmitted through direct contact with the fluid from shingles rash vesicles, not through casual contact or airborne routes. 1

Transmission Mechanism

Varicella-zoster virus (VZV), which causes both chickenpox (varicella) and shingles (herpes zoster), has specific transmission patterns:

• Primary transmission route: Direct contact with fluid from active shingles lesions 1
• Secondary routes:
  • Respiratory secretions may contain the virus 1
  • Aerosolized droplets from vesicular fluid 1

A person with shingles is contagious from the time the rash appears until all lesions have crusted over, typically 4-7 days after rash onset 1.

Important Distinction

• Shingles itself is not transmitted from person to person
• What transmits is the varicella-zoster virus, which causes:
  • Chickenpox in susceptible individuals who have never had chickenpox or vaccination
  • NOT shingles directly (shingles occurs only through reactivation of latent virus)

Risk to Susceptible Individuals

Exposure to a person with active shingles poses significant risk to:

• Individuals who have never had chickenpox or varicella vaccination 1
• Immunocompromised individuals 2
• Pregnant women without immunity to VZV 1
• Newborns whose mothers develop varicella around delivery 2

Prevention Strategies

1. For people with active shingles:

   • Cover rash completely until all lesions have crusted over
   • Avoid contact with high-risk individuals
   • Practice good hand hygiene after touching lesions

2. For susceptible individuals exposed to shingles:

   • Varicella-zoster immune globulin (VZIG) should be administered within 96 hours of exposure for high-risk individuals 1
   • Post-exposure vaccination may be appropriate for eligible individuals 2

3. Preventive vaccination:

   • Recombinant zoster vaccine (RZV) is recommended for adults 50 years and older to prevent shingles 1
   • Varicella vaccination for susceptible household contacts of immunocompromised individuals 1

Clinical Implications

Healthcare providers should:

• Recognize that patients with shingles can transmit VZV to susceptible individuals
• Advise patients with shingles to avoid contact with pregnant women, infants, and immunocompromised individuals
• Consider post-exposure prophylaxis for high-risk contacts
• Recommend appropriate vaccination for prevention

Common Misconceptions

• Misconception: Shingles is directly contagious and causes shingles in others
• Reality: Exposure to shingles can only cause chickenpox in susceptible individuals, not shingles
• Misconception: Casual contact with someone who has shingles is risky
• Reality: Transmission requires contact with vesicle fluid or possibly respiratory secretions

The best prevention strategy is vaccination, with the recombinant zoster vaccine (RZV) being strongly recommended for adults 50 years and older due to its high effectiveness (90-97%) in preventing shingles 3.