Chickenpox (Varicella) Disease

Fact Sheet Adobe Portable Document Format (PDF)59KB

What is chickenpox disease?

  • Chickenpox, or varicella, is a very common childhood infection that can also affect adults.
  • It is caused by the varicella-zoster virus, which only infects people.
  • Most cases occur in the late winter and spring.
  • About 95% of Canadians catch chickenpox in childhood. In Canada, there are about 350,000 new cases each year in children and teens under 15 years of age.
  • While chickenpox is a mild to moderate illness in the majority of children, it can be much more severe in teens and adults.

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How can I get chickenpox?

  • The virus spreads easily:
    • from person to person through the air when an infected person sneezes or coughs.
    • through direct contact with the saliva of a person who has chickenpox.
    • by contact with the fluid from chickenpox blisters.
  • Chickenpox is most contagious 1 - 2 days before the rash appears.

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Are some people more at risk for serious chickenpox illness?

  • Chickenpox disease can cause serious complications (problems) in:
    • People who have not had chickenpox and are not vaccinated .
    • Newborn babies.
    • People with a weak immune system.
    • Pregnant women as they can pass the disease to their unborn baby (possibly causing birth defects).
    • Teens and adults.
  • People from the tropics may not be immune to the illness as chickenpox is less common in tropical countries.

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Can I get chickenpox more than once?

  • Immunity to chickenpox disease is generally life long.
  • However, the body does not get rid of the virus. Instead, the chickenpox virus lies dormant (asleep) in nerve cells in the body. Years later, the virus may become active again and cause a painful condition known as shingles.
  • This will happen in 10% - 15% of all people who had chickenpox.

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How do I know if I have chickenpox?

  • The first symptoms of chickenpox are similar to those of the common cold - mild fever, aches and pains, a headache and loss of appetite. This lasts for 1 - 2 days. People with chickenpox are highly infectious at this time.
  • 1 - 2 days later, a rash develops. Itchy red spots appear first on the face and scalp, and then spread quickly down the body and to the arms and legs. The spots may even be painful.
  • Small blisters appear, filled with a clear fluid. The fluid in these blisters becomes cloudy. The blisters break and then a crust or scab forms while the skin heals. New "crops" of spots continue to appear over a 3 - 4 day period.
  • Some people will only have a few blisters while others will have many blisters over their entire body. The illness is usually mild but may be accompanied by a high fever and severe rash.

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If I have contact with chickenpox, how long does it take to become ill?

  • The chickenpox rash can appear from 10 - 21 days after contact with someone who is infected with chickenpox.
  • Usually the symptoms appear in 14 - 16 days.

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How is chickenpox diagnosed?

  • The rash of chickenpox is very typical.
  • Chickenpox can usually be diagnosed without laboratory tests.

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What can happen if I get chickenpox?

  • Between 5% - 10% of all healthy children who get chickenpox will develop complications such as:
    • skin infections. These are a common problem. Most are mild, but chickenpox has been linked to a life-threatening infection called necrotizing fasciitis or flesh-eating disease (also known as Group A Streptococcal Disease, Invasive  or G.A.S.).
    • pneumonia (infection of the lungs).
    • encephalitis (severe inflammation of the brain).
    • a sudden loss of muscle co-ordination and difficulty in walking.
  • Complications of chickenpox are much more frequent and severe in adults. The death rate from chickenpox in adults is 25 times higher than in children – mainly due to pneumonia and encephalitis.
  • Chickenpox may cause damage to the unborn child if a pregnant woman becomes infected during the early part of her pregnancy. If the mother develops chickenpox around the time of delivery, her baby can develop very severe chickenpox which can be life-threatening.
  • Every year, more than 1,800 people are hospitalized for complications of chickenpox. It is estimated that one person in 33,000 will die from chickenpox. Over 90% of these deaths occur in previously healthy persons.

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Can chickenpox be treated?

  • There is no cure for chickenpox. However, there are medications that can make chickenpox illness less severe in people who are at higher risk.
  • Encourage children with chickenpox to practise good hand-washing and keep their fingernails short. This is very important because germs on the hands and skin can infect the sores. Ask your doctor or your pharmacist about things you can do to help reduce the itching and to relieve fever.
  • If fever does occur, do not use products that contain salicylates, such as aspirin, ASA, 222’s, 292’s or willow bark. Taking aspirin increases the risk of getting Reye's syndrome. This is a severe illness that can damage the liver and brain, especially in children.
  • Contact a physician as soon as possible if the ill person:
    • has a fever over 38.5°C that lasts more than 2 days or comes back.
    • develops redness swelling and severe pain around any of the spots.
    • has a severe headache, constant vomiting, sensitivity to bright light or unusual sleepiness or confusion.

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What should I do if I think I have chickenpox?

  • If you think you have chickenpox, call your doctor’s office.
  • Tell them about your symptoms.
  • Do not go to your doctor without calling ahead. The office needs to arrange appropriate infection control  measures for your appointment so that the infection is not passed to others.

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How long should I stay at home?

  • There are no exclusion requirements for chickenpox disease.
  • Someone who has chickenpox disease may go to daycare, preschool, school, or work if he or she does not have a fever and he or she is capable of completing a full day of normal activity.
  • Chickenpox is a reportable communicable disease ( Adobe Portable Document Format (PDF) 48KB). Please advise your daycare, preschool or school if your child has chickenpox.

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What can I do to prevent chickenpox?

  • Get vaccinated! Most people who get the vaccine do not get chickenpox. If they do, it is usually mild, with a minor rash. If given within 3 days of exposure, the vaccine can prevent chickenpox or reduce its severity. Chickenpox vaccine is routinely offered to toddlers at 15 months of age and to children entering school for the first time.
  • Older children, teens and adults can also receive the chickenpox vaccine. It may not be publicly-funded for people in these age groups.
  • Get more information about Chickenpox Vaccine (Varilrix® or Varivax®).

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Who can I call for more information?

For more information about chickenpox or immunization against chickenpox, talk to your health care provider or call the Health Department.

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