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CHICKENPOX (Varicella Virus)

Environmental Health & Prevention Services

This page was reviewed or revised on Thursday, August 13, 2009.

PDF of Fact Sheet

What is Chickenpox?

Chickenpox is a contagious viral illness caused by the varicella zoster virus. Chickenpox is a common childhood infection. The virus usually causes a mild fever followed by raised red spots which then become fluid filled blisters. Within a few days, crusts form over the blisters scabbing over within 5 to 7 days. The chickenpox rash may be very itchy.

What are some Complications of Chickenpox?

Complication of chickenpox include pneumonia, secondary bacterial infection of the pox rash, dehydration, and encephalitis (inflammation of the brain). These complications rarely occur.

What do Chickenpox and Shingles have in Common?

The varicella virus may lie dormant in the body for many years after the chickenpox infection. If the virus becomes active late in life, it may cause a painful rash known as ‘shingles’. Since the same virus causes both chickenpox and shingles, a person who has never had chickenpox may get the chickenpox from being exposed to someone with shingles.

How is Chickenpox Spread?

The virus is spread from person to person through contact with nose and throat secretions, or contact with vesicle fluid.  Generally it takes 14-21 days for symptoms to occur.

How long is Chickenpox Contagious?

Chickenpox is most contagious 1-2 days prior to onset of rash, until lesions are crusted and fever has subsided. There is no cure for chickenpox and it is possible to get the illness more than once. However, prevention is your best protection.

How can I Prevent Chickenpox?

There is a vaccine called Varivax II, licensed in Canada in 1998 to prevent chickenpox. Children over 12 months of age can receive the free vaccine on the same day as the MMR vaccine or at least one month apart.

Vaccination in adult females must be completed at least one month before becoming pregnant. There is a cost to adults for the vaccine so adults and older children should have a blood test to determine whether they are already immune to varicella. Children over 13 years of age need 2 doses of the vaccine spaced one month apart.

The vaccine may be effective in preventing chickenpox if given within 72 hours of exposure to a chickenpox case. Call your family physician and/or local health unit.

What is the Concern with Chickenpox and Pregnancy?

Infections within the first three months of pregnancy may lead to malformation and damage to the fetus. If a pregnant mother is exposed to chickenpox it is important to determine her immune status. Varicella Zoster Immune Globulin may be given in emergency situations and must be prescribed by a physician. Pregnant females should contact their family physician as soon as possible if they have not had chickenpox in the past and are exposed to someone with chickenpox.

What is the Treatment?

Infections within the first three months of pregnancy may lead to malformation and damage to the fetus. 

• Control the fever but do not use aspirin (acetylsalic acid, A.S.A.) or any products that contain aspirin if a child gets chickenpox. Aspirin increases the risk of severe illness called Reye’s Syndrome in children with chickenpox and other viral infections. Reye’s Syndrome can damage the liver and brain. However, it is safe to use acetaminophen (Tylenol, Tempra, and others) to control fever.
  
  

• Encourage good personal hygiene in the child with chickenpox. This is important because the sores can easily become infected by bacteria, and cause secondary bacterial infections.
  
  

• Signs of bacterial infection:

• Redness

• Swelling

• Area warm to touch

• Any discharge which is greenish in colour.
  

Related Link:  Chickenpox (Varicella Vaccine)

For further information, please contact the Community Health Services Department at 519-383-8331 or 1-800-667-1839.

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