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What is Chickenpox (Varicella)?

Chickenpox is an infection caused by the varicella-zoster virus. It is most common in children. When adults get it, they can be very sick.

  • Infection with chickenpox may begin with a mild fever, followed in a day or two by a rash which may be very itchy.
  • The rash starts with red spots that soon turn into fluid-filled blisters. In a few days, crusts form over the blisters.
  • The chickenpox rash usually appears 10 to 21 days after exposure to the virus.
  • Chickenpox can be a mild disease, but can cause serious health problems, such as pneumonia, or an infection in the brain.

How is Chickenpox Spread?

The chickenpox virus spreads very easily through the air or through direct contact with the fluid from a chickenpox blister. It is highly contagious among people who are not immune and can spread within childcare facilities, schools and families. Chickenpox is contagious one to possibly five days before the rash starts. A person can continue to spread it to others for up to five days from when the rash begins or until all the blisters have crusted over, whichever comes first.

When can Children with Chickenpox Return to Childcare or School?

Children can return as soon as they feel well enough to participate in all regular activities, regardless of the state of the rash.

How is Chickenpox Treated?

  • People with chickenpox usually get better on their own, usually with no medical treatment.
  • Never give aspirin (acetylsalicylic acid), or any products that contain aspirin, to a person with chickenpox. Aspirin can increase the risk of a severe illness called Reye’s syndrome in people with chickenpox and other viral infections. To control fever, use acetaminophen such as Tylenol, and Tempra.
  • For people with a high risk of complications, health care providers sometimes prescribe medications to shorten the duration of the infection. If complications do develop, the health care providers will determine the appropriate treatment.
  • Calamine lotion may help with the itching. Keep fingernails short to prevent scratching and scarring.

How can Chickenpox be Prevented?

The best way to prevent chickenpox is by being immunized with the varicella vaccine. Vaccine efficacy in children is estimated to be 94% after one dose and 98% after a second dose. Two doses of chickenpox vaccine protects most individuals or reduces the severity of the disease.

Varicella vaccine is recommended for healthy children ages 12 months to 12 years of age. In Ontario, routine childhood immunization for chickenpox is at 15 months and four to six years of age. Children born on or after January 1st, 2010, need to show proof of immunization against chickenpox to attend school.

Children who were born on or after January 1st, 2000 are eligible to get two doses of the publicly funded free vaccine.

Adults 18 to 49 years of age who have never had the chickenpox disease, should get two doses of the vaccine, three months apart, although it is only publicly-funded free for persons with certain risk factors.

Women who have not had chickenpox and are considering a future pregnancy may receive the vaccines. Women should not become pregnant for one month after receiving the chickenpox vaccine. Chickenpox vaccine should not be used in pregnancy.

Chickenpox and Pregnancy

Pregnant women who become infected with chickenpox, can develop severe disease. Infection during pregnancy may lead to problems for the baby.

  • If you are pregnant, have been in contact with someone who has chickenpox, and are unsure if you have had chickenpox, consult your health care provider as soon as possible after the exposure.
  • A blood test is available to determine if you have enough antibodies to protect you from the virus. Depending on the blood test result, there may be further follow-up with your health care provider.
  • Women should be tested for immunity before they become pregnant.

Where can I get more information?

Call the Perth District Health Unit’s Health Line at 519-271-7600 or toll-free at 1-877-271-7348 extension 267.

November 2017