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Chickenpox

Chickenpox (varicella) is a common, preventable childhood infection caused by the varicella-zoster virus.  It’s most common in children and is usually mild, but can be very uncomfortable for your child. When adults get it they can be very sick.

Chickenpox is very dangerous for people with immune system problems like leukemia, or for people who are taking drugs that weaken the immune system (such as steroids).

What are the symptoms?

  • Chickenpox begins with a fever.
  • Within 1 to 2 days your child will get a rash that can be very itchy.
  • It starts with red spots that soon turn into fluid-filled blisters.
  • Some people have only a few blisters. Others can have as many as 500.
  • These blisters dry and form scabs in 4 or 5 days. 

How is it spread?

Chickenpox spreads easily. It can spread from 2 days before the rash appears but is most contagious 12 to 24 hours before the rash appears, so it’s easy to spread it without knowing. It usually develops 2 to 3 weeks after contact with an infected person.

  • It spreads from person to person through direct contact with the virus. You can get chickenpox if you touch a blister, or the liquid from a blister. You can also get chickenpox if you touch the spit of a person who has it.
  • The virus enters the body by the nose or mouth.
  • It can also spread through the air.
  • A pregnant woman with chickenpox can pass it on to her baby before birth.
  • Mothers with chickenpox can also give it to their newborn babies after birth.

The only way to stop the spread of the virus from person to person is to stop infected people from sharing the same room or house, which isn't practical.

Chickenpox doesn’t spread through indirect contact. That means it doesn’t live on objects like sheets, counters or toys.

Is there a vaccine against chickenpox?

Yes.

  • Children should get 2 shots for chickenpox: the first when they are 12 to 18 months old and a second “booster” shot when they are 4 to 6 years old.
  • Teens (13 years and older) who have never had chickenpox should get 2 shots, at least 4 weeks apart.

What is shingles?

Shingles happens in people who have already had chickenpox, usually many years later. It looks like chickenpox and is caused by the same virus. But it usually appears on only one part of the body. Shingles is contagious, but is less contagious than chickenpox because it doesn’t spread through the air.

  • You can catch chickenpox from someone with shingles through contact with their saliva or their skin rash.
  • You cannot get shingles from someone with chickenpox.

Can you have chickenpox twice?

In most cases, you can only get chickenpox once. This is called life-long immunity. But in rare cases, a person might get it again, especially if you were very young when you had it the first time.

What can I do to protect my child?

The best way to protect your child from chickenpox is vaccination.

If your child is not yet vaccinated and comes in contact with another child or family member who has chickenpox, he may still be protected if he is vaccinated right away.

If one of your children has chickenpox, it will probably spread to other members of the household who have not already had chickenpox or the vaccine.

How can I treat chickenpox?

  • If your child gets chickenpox, do not give aspirin [acetylsalicylic acid (ASA)] or any products that contain aspirin. Taking aspirin increases the risk of getting Reye's syndrome. This severe illness can damage the liver and brain. If you want to control your child's fever, use acetaminophen (Tylenol, Tempra, Panadol and others).
  • Encourage your child not to scratch. Scratching can cause infection from bacteria that get into the skin. Adding baking soda to the bathwater can be soothing. Your doctor may recommend a cream to help reduce the itch.

When should I call the doctor?

  • Your child’s fever lasts more than 2 days and is over 38.5°C.
  • A new fever develops after the first couple of days. That is, the fever goes away for a day or so and returns.
  • Your child develops a skin infection and looks ill, especially if he also has a high fever. Your doctor will decide if your child has developed a bacterial infection that needs antibiotics.
  • A chickenpox spot becomes enlarged, red or very sore.
  • Your child seems very ill.
  • Your child has an immune system disorder. The doctor can give a special type of immune globulin (VZIG) with a large number of antibodies to help prevent infection, or early treatment with an antiviral drug.

Can my child with chickenpox go to child care or school?

Many schools and daycare centres have policies that require children with chickenpox to stay home for five days after their rash appears. The goal is to protect other children from the disease. Unfortunately, this does not stop chickenpox from spreading.

Chickenpox is contagious from 2 days before the rash appears, and most infectious from 12 to 24 hours before the rash appears. It spreads through the air, not just by direct contact with the rash. Exclusion policies (policies that require that your child stay home for a period of time) don't work because by the time it's known that a child has chickenpox, it has already been passed on to other children.

If your child is too sick to take part in regular activities, or if he has a fever, he should stay home. Many children with mild chickenpox are otherwise well. For mild cases (low fever for a short period of time and only a little rash, less than 30 spots) children can go to child care or school as long as they feel well enough to take part in regular activities, even if they still have the rash.

What if I'm pregnant?

Pregnant women can develop severe chickenpox. Most adult women are already protected against chickenpox by antibodies in their blood. If you are thinking of getting pregnant and have not had chickenpox, ask your doctor about whether you can be vaccinated.

If you are pregnant and have not had chickenpox, or if you have not lived in the same house with someone who has had chickenpox or shingles, call your doctor right away if you are exposed to chickenpox. Your doctor may want to give you a special type of immune globulin (VZIG) injection to help prevent you from getting a severe infection. 

If you catch chickenpox early in your pregnancy, there is a very small chance of it harming your unborn baby. 

For complete information on vaccinations in Canada, read Your Child's Best Shot: A parent's guide to vaccination



Reviewed by the following CPS committees:
Infectious Diseases and Immunization Committee

Last Updated: September 2011

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