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Chickenpox

• Chickenpox is a very contagious viral disease that causes an itchy outbreakof skin blisters.
• The chickenpox virus spreads from person to person by direct contact with fluid from broken chickenpox blisters. It also spreads through the air.
• Chickenpox is usually a mild disease. However, in adults and children with weakened immune systems, chickenpox can cause serious complications and even death.
• A vaccine is now available to prevent chickenpox.

What is chickenpox?

Chickenpox is a very contagious disease that causes an itchy outbreak of skin blisters.

What is the infectious agent that causes chickenpox?

Chickenpox is caused by the varicella zoster virus. The same virus causes both chickenpox (varicella) and shingles (zoster). Varicella zoster virus is a member of the herpes virus family.

How do people get chickenpox?

Chickenpox spreads from person to person by direct contact with fluid from broken chickenpox blisters or through the air by coughing or sneezing. Chickenpox is so contagious in its early stages that an exposed person who has not had chickenpox has a 70% to 80% chance of getting the disease.

After infection, the virus stays in the body for life. Although people cannot get chickenpox twice, the same virus causes shingles. A person with shingles can spread the virus to an adult or child who has not had chickenpox, and that person can develop chickenpox.

What are the signs and symptoms of chickenpox?

Chickenpox typically produces a mild fever and an itchy outbreak of blisters on the scalp, face, and torso. The blisters dry and become scabs in 4 to 5 days. The blisters occur in successive crops that can produce hundreds of scabs. An infected person is contagious from 1 to 2 days before the rash appears and until all blisters have formed scabs.

 How soon after exposure do symptoms appear?

Symptoms usually start within 2 to 3 weeks after contact with an infected person.

How is chickenpox diagnosed?

Chickenpox can usually be diagnosed by symptoms. A blood test is available to confirm the diagnosis if necessary.

Who is at risk for chickenpox?

Anyone who has not had chickenpox is at risk after exposure to an infected person.

What complications can result from chickenpox?

Although most people recover from chickenpox uneventfully or with a few minor scars, a small percentage suffer more serious complications. Each year in the United States, 4,000 to 9,000 persons are hospitalized with chickenpox, and up to 100 persons die. Those at highest risk for complications are newborns, persons with weakened immune systems, and adults. Although adults make up fewer than 5% of chickenpox cases in the United States, they account for half of the deaths from the disease.

The most common complications of chickenpox are skin infections and pneumonia. Other complications are encephalitis (inflammation of the brain) and hepatitis. Chickenpox can also lead to severe problems in pregnant women, causing stillbirths, birth defects, or infection of the newborn during childbirth.

What is the treatment for chickenpox?

Anti-virus medicine is available for treatment, but it is used mostly in adults and others who are at risk for developing more serious disease. Skin infections, a common complication of chickenpox, can be prevented by keeping blisters clean and not scratching them.

How common is chickenpox?

Almost everyone gets chickenpox by adulthood. In the United States, chickenpox affects about

4 million persons per year, mostly children. In temperate climates, most cases occur in the late winter and spring.

Although most people think that chickenpox is always a mild disease, deaths from chickenpox continue to occur in the United States. In 1997, three young adults died from complications of chickenpox. All three were infected by unvaccinated pre-schoolers.

How can chickenpox be prevented?

Persons infected with chickenpox should avoid exposing others who might be at risk of getting the disease. People with symptoms should stay home until 1 week after the skin blisters appear or until the blisters become dry.

A vaccine to protect children against chickenpox was licensed in 1995. The vaccine is recommended for all children at 12-18 months of age. Older children who have not had chickenpox should receive the vaccine before their 13th birthday. Adults who have not had the disease should also be vaccinated, as should anyone who is a close relative or contact of those who are at high risk for complications. The vaccine prevents chickenpox in 70% to 90% of those who receive it. People who develop the disease after the shot have milder symptoms.

As is the case with all immunizations, there are important exceptions and special circumstances. Health-care providers should have the most current information on recommendations about the chickenpox vaccination.

This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health-care provider. If you have any questions about the disease described above or think that you or a family member might have chickenpox, consult a health-care provider.

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