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Chickenpox (varicella)

Chickenpox (varicella) is a highly contagious disease caused by the varicella-zoster virus. Chickenpox can affect people at any age although children usually have a mild illness and recover quickly.

Signs and Symptoms: 

Chickenpox usually begins with cold-like symptoms such as a mild fever, headache, runny nose, and cough. A day or 2 later a rash appears as small pink blotches that change to itchy fluid-filled blisters lasting 3 to 4 days before drying out and turning into scabs. Children who are otherwise healthy can develop between 200 and 500 skin lesions.

Treatment: 

No specific treatment is recommended or required for otherwise healthy children and adults with chickenpox. A person with chickenpox can usually be managed at home and will not need to see a doctor. Sick children may not want to drink fluids, but it is important to encourage small sips of water, icy poles, soup, and other fluids often to prevent dehydration.

It is also important to try to prevent scratching the rash as this can result in permanent scarring or secondary skin infection. You can relieve symptoms by:

  • resting while unwell
  • having lukewarm baths with baking soda, oatmeal or an anti-itch solution (e.g. pinetarsol) added to the water
  • applying creams or lotions such as calamine lotion to reduce the itching
  • taking paracetamol to reduce fever or discomfort.

Aspirin must not be given to young children and adolescents due to the risk of developing a severe condition called Reyes Syndrome. This is particularly important for children who have or who may be developing chickenpox.

Transmission: 

Chickenpox is spread person to person through coughing, sneezing and direct contact with the fluid in the blisters of the rash. Since shingles blisters also contain the virus, a person who has never had chickenpox can become infected with chickenpox from someone who has shingles.

An individual with chickenpox is infectious for about 1 to 2 days before the onset of the rash and until all of the blisters have scabbed over, usually 4 to 5 days. The usual time between contact with the virus and developing the illness is about 14 to 16 days, although sometimes it can take longer.

Prevention: 

Immunisation

Immunisation is the best way to protect against chickenpox and a safe and effective vaccine is available in Australia. The vaccine almost always prevents severe infection. However, it is also important to maintain good hygiene practices, such as regular hand washing, particularly after contact with a sick person.

If a person has already had chickenpox, they are immune to the disease and do not need to be vaccinated. If there is uncertainty whether a person has had chickenpox, it is safe to have the vaccine.

Like all medications, vaccines may have side effects. Most side effects are minor, last a short time, and do not lead to any long-term problems. There may be some swelling, redness, and soreness where the injection was given and fever. A mild chickenpox-like rash may develop at the injection site or on the body. If this occurs, the rash usually appears about 8 days after vaccination (but can appear any time between 5 to 26 days). People with this rash should avoid contact with people with weakened immune systems. More serious side effects are extremely rare. Contact your immunisation provider if you or your child has a reaction following vaccination which you consider serious or unexpected.

Some vaccinated children will still get chickenpox (‘breakthrough varicella’) however they will generally have a much milder form of the disease (with less than 50 skin lesions in about 70% of cases) and recover more quickly. The fluid in the skin lesions in breakthrough varicella can be contagious. The National Immunisation Program (NIP) Schedule provides a combined measles, mumps, rubella and varicella (MMRV) vaccine free of charge to all children aged 18 months. Prior chickenpox infection is not a contraindication to this vaccine, and such children with a history of chickenpox infection should still receive MMRV vaccine.

It is preferable that children receive 2 doses of the vaccine. A second dose is not included on the NIP Schedule. Parents can discuss this and any costs with their general practitioner.

Queensland Health provides funded varicella vaccination to non-immune individuals less than 20 years of age if no previous varicella vaccinations have been recorded. For over 14-year-olds, this requires 2 doses given at least 4 weeks apart to achieve adequate protection from chickenpox.

Vaccination is also recommended (but not funded) for non-immune people in the following groups:

  • high-risk occupations where exposure to chickenpox is likely (eg. healthcare workers, teachers, childcare staff)
  • women planning a pregnancy (chickenpox vaccine should not be given during pregnancy and women are advised to avoid becoming pregnant for 28 days after vaccination)
  • women immediately after delivery of a baby
  • parents of young children
  • household contacts of people with lowered immunity.

Post exposure

Varicella vaccine has been shown to reduce the likelihood of chickenpox in previously unvaccinated people if given within 3 days, and possibly up to 5 days, after contact with an infected person, with earlier administration preferable. An injection of zoster immune globulin (ZIG) given within 96 hours of exposure to chickenpox provides immediate but temporary protection against chickenpox and may be recommended if exposure has occurred for individuals at high risk of severe disease or pregnant women who are not immune to chickenpox. ZIG is not recommended for otherwise healthy children or adults. ZIG will not treat established chickenpox. 

Women who are pregnant or breastfeeding

If a woman develops chickenpox during pregnancy, there is a small but serious chance of damage to her unborn baby. If she develops chickenpox late in pregnancy or very soon after birth, the infection can be serious and cause severe chickenpox in the newborn baby or damage to their eyes, limbs, or nervous system. Pregnant women and those with newborn infants in their first month of life, who have had household or face to face contact with a person with chickenpox, should seek urgent medical attention. Breastfeeding women can receive the varicella vaccine. Most live vaccines are not secreted in breast milk. Women who received the varicella vaccine while breastfeeding showed no evidence of varicella-zoster virus DNA in breast milk samples and no effects on breastfed infants have been reported.

Health outcome: 

For the majority of children, chickenpox is a mild illness of short duration with complete recovery, however it can be more severe in newborn babies and adults, particularly in people who are immunocompromised. Infections in pregnancy can pose a risk to the unborn child.

Complications from chickenpox infection occur in approximately 1% of cases with the most common being secondary bacterial infections caused by scratching skin lesions. People who are immunocompromised may develop other complications including pneumonia, encephalitis (inflammation of the brain), thrombocytopaenia (very low platelet levels in the blood) and hepatitis (inflammation of the liver).

Chickenpox can also cause shingles (herpes zoster) in later life.

Control

If you have chickenpox you can help stop the spread by washing your hands often and covering your cough or sneeze. In Queensland, chickenpox is listed as a contagious condition under the Public Health Act 2005. To prevent the spread of chickenpox among children at school or in childcare, parents and caregivers must not send their child to school or childcare if they suspect they have a contagious condition. People with chickenpox should avoid going to childcare, schools or work for at least five days after the rash first appears and until dry scabs have replaced all blisters. Any contacts with lowered immunity, such as those with leukaemia, should be immediately excluded and referred to their GP or specialist for further advice.

Help and assistance: 

Get qualified health advice 24/7 for the cost of a local call. 13 HEALTH (13 43 25 84)

You should take your child to see a doctor if they become increasingly unwell, have a persistent fever, are drowsy, or are not taking fluids.

If you are in an emergency situation, call 000

For further assistance, please contact your local doctor, community health centre, or nearest public health unit.

References

Heymann, D., ed.2015. Control of Communicable Diseases Manual, 20th edition. Washington, DC: American Public Health Association, pp669-675.

Australian Immunisation Handbook. (2022). Australian Government Department of Health: https://immunisationhandbook.health.gov.au/

Clinical Practice Guidelines. Retrieved from The Royal Children's Hospital Melbourne:
https://www.rch.org.au/clinicalguide/guideline_index/Chickenpox_varicella/