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Infectious Diseases

Chickenpox (Varicella)

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What is chickenpox?

Chickenpox is caused by the varicella-zoster virus and is a common, preventable childhood infection. It is usually mild in children; however some adults can be very sick. Chickenpox can be dangerous for people with a weak immune system. Once you have had chickenpox, you should not get it again. 

How do I know if I have chickenpox?

It is important that you see your health care provider if you think you have chickenpox. When making an appointment, let your health care provider’s office know that you may have chickenpox so they can take special care to prevent spreading it to other people. 

What are the symptoms?

Chickenpox begins with a fever, headache, sore throat or stomach ache. About two to three days later, itchy red bumps that look like pimples appear and become small fluid-filled blisters that typically heal within five days. Some people may only experience a few blisters; while others can have many blisters over their entire body. Blisters can become infected and in rare cases chickenpox can cause other complications like pneumonia and encephalitis.

How is it transmitted?

Chickenpox spreads easily through the air (coughing, sneezing) and contact with saliva or blister fluid. It is most contagious on the day before the rash appears and continues until all lesions are crusted over (usually about 5 days). Symptoms of chickenpox will appear two to three weeks after exposure.

Is there a chickenpox vaccine?

Yes. The vaccine is free for all Ontario children born after January 2000 and for people in certain high risk groups.

It is routinely given at 12-15 months of age.  A booster is given again between 4-6 years of age. 

What can parents do?

The best way to protect your children from chickenpox is to have them vaccinated.

Your child may still be protected if he comes into contact with chickenpox and is vaccinated within three to five days.

If your child has an immune system disorder, contact your health care provider. Your health care provider can give your child a special type of immune globulin which contains a large number of antibodies to help prevent infection, or they can provide early treatment with an antiviral drug.

If your child has a fever, 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, it is safe to use acetaminophen (Tylenol®, Tempra®, Panadol® and others)

Keep a child with chickenpox home if the illness is severe enough that the child cannot participate in regular activities or if the child has a fever. For mild cases, exclusion is not necessary as long as they feel well enough to take part in regular activities, even if they still have a rash

What if I’m pregnant?

Pregnant women can develop severe chickenpox. Most adult women already have protective antibodies to chickenpox in their blood. If you are pregnant, have not had chickenpox and have been around someone with chickenpox or shingles; contact your health care provider right away. Your health care provider may want to give you a special type of immune globulin to prevent severe infection.  

If a pregnant woman gets chickenpox during pregnancy, the fetus is at risk for birth defects. 

What is shingles?

Once you are infected with chickenpox, the virus stays in your body in an inactive form. Later in life the virus can become active again causing shingles (zoster). Shingles is a painful rash that can be serious if it occurs on the face or near the eyes.   You can get chickenpox from shingles, but you cannot get shingles from shingles.

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