How is shingles transmitted?

Transmission of Shingles (Herpes Zoster)

Shingles is not directly transmitted from person to person, but the varicella-zoster virus in the fluid from shingles blisters can transmit to susceptible individuals and cause chickenpox. 1

Mechanism of Transmission

Shingles (herpes zoster) is caused by the reactivation of the varicella-zoster virus (VZV) that has remained dormant in sensory nerve ganglia following a primary chickenpox infection. This reactivation typically occurs when a person's immune function declines due to aging or immunosuppression. 1

While shingles itself is not directly contagious, the virus within the shingles lesions can be transmitted to others through:

• Direct contact with fluid from shingles vesicles/blisters
• Inhalation of aerosols from vesicular fluid of skin lesions
• Contact with infected respiratory tract secretions that may be aerosolized 1

Contagious Period and Risk

The period of contagiousness for a person with shingles:

• Begins when the rash appears
• Continues until all lesions have crusted over (typically 4-7 days after rash onset) 1

Important points about transmission:

1. A person with shingles can only transmit VZV to individuals who have never had chickenpox or received the varicella vaccine
2. The transmitted virus causes chickenpox (varicella) in the newly infected person, not shingles
3. Persons with progressive shingles (development of new lesions for >7 days) may be contagious longer due to depressed immune response 1

Special Considerations

Immunocompromised Individuals

Susceptible immunocompromised individuals should avoid exposure to persons with shingles due to their higher risk of developing severe complications from varicella infection. 1

Household Contacts

Household contacts (especially children) of susceptible immunocompromised individuals should be vaccinated against VZV if they have no history of chickenpox and are seronegative for HIV, to prevent transmission to vulnerable individuals. 1

Healthcare Settings

Healthcare workers with shingles should take special precautions to avoid contact with susceptible patients, particularly those who are immunocompromised, pregnant women, or newborns.

Prevention Measures

For susceptible individuals exposed to someone with shingles:

• Varicella zoster immune globulin (VZIG) can be administered within 96 hours of exposure to prevent or modify chickenpox in susceptible immunocompromised individuals 1
• Avoid direct contact with the rash/blisters of someone with shingles
• Practice good hand hygiene after any potential contact

Key Facts to Remember

• Shingles occurs when the dormant varicella-zoster virus reactivates within a person's body - it is not acquired from external sources
• The virus in shingles lesions can cause chickenpox (not shingles) in susceptible individuals
• Transmission requires contact with the fluid from shingles blisters or respiratory secretions
• Once all lesions have crusted over, the person with shingles is no longer contagious
• Breakthrough varicella in vaccinated persons can also be contagious, though typically milder 1

Understanding these transmission dynamics is crucial for preventing the spread of VZV from individuals with shingles to susceptible contacts, particularly those at high risk for severe disease.