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Chickenpox and Herpes Zoster (Varicella virus)


Tell me more about chickenpox and zoster.

Both chickenpox and zoster (shingles) are caused by the varicella virus. Chickenpox is typically an infection of childhood, marked by an outbreak of pus-filled vesicles all over the body. While most cases pass without complication, chickenpox was the cause of thousands of hospitalizations and hundreds of deaths before the routine use of the varicella vaccine.

Zoster is the re-emergence of the varicella virus that has lived dormant in the nerve endings for years, causing a localized rash and blistering. It is most common in persons over 50, and it is speculated that the waning immunity of older persons to a childhood varicella infection is what allows the virus to replicate and cause disease again.

How are chickenpox and zoster transmitted?

Although chickenpox is characterized by a systemic rash, the varicella virus primarily infects the respiratory tract. Therefore, chickenpox is usually transmitted when an infected person coughs or sneezes, although direct contact with the chickenpox lesions themselves can also cause an infection.

For persons with zoster, direct contact with the rash and/or blisters is sufficient to transmit varicella and cause a case of chickenpox. Zoster itself is not contagious because it is the reemergence of a dormant infection and not a new case of disease. It is thought that zoster may be an important source of chickenpox disease in young children, especially as more and more children are vaccinated.

Varicella is extremely contagious: it is estimated that up to 90% of susceptible persons will contract chickenpox from an infectious person.

What are the symptoms of chickenpox and zoster?

Approximately 10 to 21 days after a person has been infected with the varicella virus, they will begin to show symptoms of chickenpox. These include fever, tiredness, and a rash that begins on the face and trunk. A person with chickenpox is considered contagious for 1-2 days before the rash until the blisters scab over.

Zoster presents as a red, itchy, painful rash that may also blister. The rash is localized to a small patch on one side of the body, the exact location of which is determined by which nerve the varicella virus inhabits. While the rash typically heals on its own, the pain can persist for months or years after the rash disappears.

How are chickenpox and zoster treated?

Treatment for uncomplicated cases of varicella disease is mainly supportive. If complications occur, then they may be treated with antibiotics or antivirals as necessary.

It is important never to give a child under the age of 18 aspirin if they are infected with varicella, as this has been linked with a liver disease called Reye's Syndrome.

How can I prevent chickenpox and zoster?

The most important thing you can do is to have your child vaccinated, as well as any other susceptible adults in your household. If a person in your household contracts chickenpox, and you are susceptible, it may be possible to prevent disease if you receive the varicella vaccine right away.

"Pink Book on Immunization" chapter on varicella:


CDC Info on varicella: