Chickenpox

Caused by the varicella zoster virus

Chickenpox is a common childhood illness that causes an itchy, blistering rash. Chickenpox is easily spread by an infected person sneezing and coughing, or by contact with weeping blisters when the sores are present. Children with chickenpox need to stay home from school and daycare. Chickenpox is infectious 2 days before the rash is present until all the blisters have dried up. This usually takes 5 to 7 days.

infant with chickenpox

Key points

  1. Even though chicken pox is mainly a childhood illness, adults who are exposed to the virus can still get chickenpox if you have not chickenpox previously or have not been vaccinated against it.
  2. Most cases of chickenpox are mild, but it can cause more serious illness in adults, during pregnancy and in people with a weakened immune system.
  3. Vaccination for chickenpox is free for children turning 15 months of age and children turning 11 years of age who have never been infected with or previously vaccinated for chickenpox. Read more about the chickenpox vaccine.

What causes chickenpox?

Chickenpox is caused by the human herpes virus type 3, more commonly known as varicella zoster virus. It is the same virus that can cause shingles, which usually occurs later in life. 

How contagious is chickenpox?

This chickenpox virus is highly contagious, meaning it is very easy to catch. It is spread by sneezing and coughing, or by contact with weeping blisters when the sores are present. You can even catch the chickenpox virus from touching clothing or other objects that have fluid from the blister on them.

How long will it take to get chickenpox after being in contact with it?

Generally, the time from infection to appearance of the rash (incubation period) for chickenpox is usually 14 to 16 days but can range from 10 to 21 days. A few days before the first spots appear, you or your child may have a fever, with a sore throat and headache.

You are infectious 2 days before getting the rash until all the blisters have dried up. This usually takes 5 to 7 days.

Who is at risk of getting chickenpox?

You are at risk of getting chickenpox if you are exposed to the chickenpox virus and have never had chickenpox or haven’t had the chickenpox vaccine. In New Zealand about 90% of those who are not vaccinated get chickenpox when they are children. If one child in your family gets chickenpox, it is highly likely that other children (or anyone in your household who hasn’t had it before) will get it also.

What are the symptoms of chickenpox?

It takes 2 to 3 weeks for symptoms to appear after infection with the virus. At first, a person with chickenpox may have cold-like symptoms, mild headache and a moderate fever.

A few days later, a red and pimply rash follows:

  • The rash normally starts on your face and scalp, and later spreads to other parts of  your body – including on your eyelids, the mouth, up the nose and in your genital region.
  • The rash continues to spread for 3 or 4 days.
  • A few hours after each 'pimple' develops, it turns into clear-fluid-filled, blister-like sore.
  • These sores usually become very itchy. 
  • After a day or so, the blisters burst, releasing the virus-containing fluid.
  • Crusts or scabs form and take 1 to 2 weeks to fall off. 
  • The spots heal at different stages, some faster than others, so your child may have the rash in several different stages at once.

Some people have mild chickenpox with under 50 spots; others have a miserable time with hundreds of spots.

Chickenpox is most infectious from 2 days before the rash is present until after scabs have formed on all the sores and no new sores develop – this takes about 7 days. Children with chickenpox need to stay home from school and daycare during this time.

Can there be complications from having chickenpox?

In most children, chickenpox is a mild disease that doesn't cause any lasting problems. Sometimes scarring can occur where the spots have been. Around 1 in 20 healthy children develop a bacterial skin infection from chickenpox. This may need to be treated with antibiotic medicine. Untreated bacterial skin infections can sometimes lead to more serious infections in the lungs or blood stream infection (septicaemia). Other complications of chickenpox are rare and include encephalitis (brain inflammation) and inflammation of your joints and kidneys.
Chickenpox tends to be more severe in adolescents and adults, pregnant women and their unborn babies and people of any age with weakened immune systems.

Contact your doctor if the person with chickenpox develops any worrying symptoms, such as:
  • very high fever
  • nausea and vomiting
  • sensitivity to light
  • stiff neck
  • confusion
  • severe headache
  • any difficulty breathing
  • drowsy and hard to wake
  • has fits (seizures)
  • unable to drink due to severe rash in the mouth
  • severe rash that looks infected or a rash that bruises or bleeds into the skin
  • becoming generally more and more unwell.

If you are concerned call Healthline on freephone 0800 611 116 for advice, or contact your doctor.

Chickenpox and pregnancy

There are potential risks for the mother and unborn baby if chickenpox occurs during pregnancy. The highest risk period is during the first 20 weeks of pregnancy. Infants exposed to chickenpox before birth are at risk of congenital varicella syndrome and may have skin scarring, eye, limb and brain abnormalities and developmental delay. Newborn babies who get chickenpox may develop severe disease that can result in death. If you’re pregnant and think you have been exposed to chickenpox, call your GP or lead maternity carer as soon as possible.

Vaccination

Pregnant women should not be given the chickenpox vaccine. The vaccine’s safety in the unborn baby has not yet been demonstrated, although no harmful effects have been described following women getting vaccinated when they didn’t realise they were pregnant.
When you get vaccinated, you should avoid getting pregnant for at least 1 month afterwards. If you are planning a pregnancy, check in early with your midwife or doctor to see whether you need to be vaccinated against  chickenpox.

How is chickenpox treated?

For some people, the rash may be no more than a passing inconvenience, but for others, it can be very unpleasant. Treatment is aimed at controlling the symptoms and supporting your body's immune system to do the rest.

The itch caused by chickenpox can be very irritating and asking your child not to scratch their itch will probably fall on deaf ears. However, it is worth trying to distract them as best you can. Scratching at spots can lead to infection, which in turn can cause scarring. 

What self-care can I do if child has chickenpox? 

  • Applying a soothing cream (emollient) such as Alpha Keri or fatty cream may help soothe the itch. Calamine lotion may be used but it can dry out the skin too much.
  • To prevent dehydration, make sure your child has plenty of clear fluids (water, thin soup or ice blocks). Don't worry if they don't eat much while they are sick – this will be fine for a day or two. 
  • Trim their fingernails as short as possible and make sure that their hands and fingernails are kept clean. 
  • Use mittens or clean socks on their hands to decrease the risk of infection from scratching, especially overnight.
  • Dress your child in loose-fitting clothing and change the bed linen daily.
  • Try giving your child a cool or luke-warm bath. Do not use soap as this will irritate their skin. Add 2 cups ground oatmeal or half a cup of baking soda to make the bath even more soothing. Pat skin dry, do not rub, after bathing. 

If you get chickenpox, you can take care of yourself by following these steps as well.

Medications 

  • Paracetamol – this can be given to help reduce the fever and ease any headaches. Make sure you measure children's doses accurately and follow the directions given on the bottle or product packaging.
  • Antihistamines – if you or your child is unable to sleep because of the itch, an antihistamine (anti-itch) medication may help. Discuss the best option with your doctor or pharmacist. 
  • Antibiotics – since chickenpox is caused by a virus, antibiotics are not used to treat it. However, if the spots look ‘angry’, red and inflamed they may have become infected, and your doctor may prescribe an antibiotic ointment to treat the infection. To prevent infection, it is important not to scratch the sores. 
  • Antiviral medicine – this may be considered in some adolescents and adults, to reduce the severity of the infection. It should be started within 24 hours of the rash appearing.

How can I prevent the spread of chickenpox? 

Chickenpox is spread through the air, when an infected person coughs or sneezes, or through contact with the fluid in the blisters. Chickenpox is infectious 2 days before the rash is present until all the blisters have dried up. This usually takes 5 to 7 days.

If my child has chickenpox 

Do not send your child to school or preschool until all the blisters have dried up. This usually takes 5 to 7 days. Wash your hands often and after tending to your child and keep coughs and sneezes covered.

For children who have not really been all that sick with chickenpox, staying at home can be a bit annoying. Remember, however, that for some children and adults, chickenpox can be a very serious illness, so it's best to do all you can to stop it spreading.
If you get chickenpox as an adult, it’s also important that you stay at home during the infectious period.

Vaccination

Vaccination for chickenpox is free for children turning 15 months of age or children turning 11 years of age who have never been infected with or previously vaccinated against chickenpox.

People with a weakened immune system are at high risk, but may not be able to have the vaccination themselves, so close contacts of these people are recommended to be vaccinated. The vaccine is funded for certain high-risk individuals and/or their close contacts. Read more about the chickenpox vaccine.

Learn more

The following links provide more information on chickenpox.

Chicken pox Ministry of Health, NZ
Immunise against chickenpox HealthEd, NZ
Chickenpox Ministry of Health, NZ
Chickenpox (varicella) The Immunisation Advisory Centre, NZ

References

  1. Varicella (chickenpox) Immunisation Handbook, 2017 NZ
  2. Chickenpox DermNet New Zealand
Credits: Editorial team. Last reviewed: 22 Nov 2017