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

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 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 percent to 80 percent chance of getting the disease.

After infection, the virus stays in the body for life. Although people cannot get chickenpox twice, the same virus can reactivate and cause shingles, a local infection of the skin than occurs along nerve pathways.

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 outbreak of itchy blisters on the scalp, face, and torso.

The blisters dry and become scabs in four to five days. The blisters occur in successive crops that can produce hundreds of scabs.

An infected person is contagious from one to two days before the rash appears and until all blisters have formed scabs.

How soon after exposure to the virus do symptoms appear?

Symptoms usually occur within two to three weeks after contact with an infected person.

How is chickenpox diagnosed?

Chickenpox is usually diagnosed by the characteristic signs and symptoms of the disease. A blood test is available to confirm the diagnosis if necessary.

Who is at risk for chickenpox?

Anyone who has not had chickenpox or has not been immunized against 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 of people have serious complications. Each year in the United States, 4,000 to 9,000 people are hospitalized with chickenpox, and up to 100 people die.

Those at highest risk for complications are:

• Newborns
• Persons with weakened immune systems
• Adults

Although adults make up fewer than five percent of chickenpox cases in the United States, they account for half of all deaths from the disease.

Complications of chickenpox include:

• Skin infections
• Pneumonia
• Encephalitis (inflammation of the brain)
• Chickenpox can also lead to severe problems in pregnant women, causing:
  • Stillbirths
  • Birth defects
  • 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. Keeping blisters clean and not scratching them can prevent skin infections.

How common is chickenpox?

Almost everyone gets chickenpox by adulthood. In the United States, chickenpox affects about 4 million people per year, mostly children. In temperate climates, most cases occur in the late winter and spring.

How can chickenpox be prevented?

• Those infected with chickenpox should avoid exposing others who might be at risk of getting the disease.
• People with symptoms should stay home until one week after the skin blisters appear or until the blisters become dry.
• A vaccine to protect children against chickenpox was licensed in 1995.
  • Two doses of vaccine are recommended for all children. The first dose should be given at 12 months of age and the second dose at four years of age.
  • Older children who have not had chickenpox should receive the vaccine.
  • Adults who have not had the disease should also be vaccinated.
  • The vaccine prevents chickenpox in 70 percent to 90 percent of those who receive it.
  • People who have been immunized but develop the disease usually experience milder symptoms than people who have not been vaccinated.

As is the case with all immunizations, there are important exceptions and special circumstances. Health care providers should have the most current information from the Centers for Disease Control and Prevention about the chickenpox vaccination.

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.

Where can I get more information?

Contact your doctor or the Southern Nevada Health District, Office of Epidemiology at (702) 759-1300.