Chickenpox | Mate koroputa hei

What causes chickenpox?

Chickenpox is caused by varicella-zoster virus, a type of herpes virus. It is the same virus that can cause shingles later in life. 

How contagious is chickenpox?

This chickenpox virus is very contagious, which means it is very easy to catch. It's spread by sneezing and coughing, or by contact with weeping blisters from chickenpox sores. You can catch chickenpox from touching clothing or objects that have fluid from blisters on them.

Generally, the time from catching the infection to seeing the rash (incubation period) for chickenpox is usually 14 to 16 days but it 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 the rash appears until all the blisters have dried up — when the spots are all scabbed over and dry. This usually takes 5 to 7 days.

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 people who are not vaccinated get chickenpox when they are children. If one child in your family gets chickenpox, it is very likely that other children (or anyone in your household who hasn’t had it before) will get it also.

It takes 2 to 3 weeks for symptoms to appear after infection with the virus. At first, a person with chickenpox may have a sore throat, headache and a fever.

A few days later, a red rash will appear:

• The rash normally starts on your face and scalp and spreads to other parts of your body. It may also cover your eyelids and mouth, and be up your nose and in your genital area.
• The rash spreads for 3 or 4 days.
• A few hours after each spot appears, it turns into a clear-fluid-filled, blister-like sore.
• These sores are usually 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, so your child may have the rash in several different stages at once.

Some people have mild chickenpox with under 50 spots; others have hundreds of spots and are very miserable.

Image: Tuomas Lehtinen - FreeDigitalPhotos.net

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, usually from scratching the spots. This may need to be treated with antibiotic medicine. Untreated bacterial skin infections can sometimes lead to more serious infections in your lungs or bloodstream 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, with pneumonia (lung infection) the most common complication. It is also more severe in pregnant women and their unborn babies and people of any age with weakened immune systems.

There are risks for the mother and unborn baby if chickenpox occurs during pregnancy. The highest risk is in 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 problems and developmental delay. Maternal chickenpox around the time of delivery can infect your newborn baby. Newborn babies who get chickenpox may have 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 because its safety in the unborn baby has not yet been proven. However, no harmful effects have been reported when pregnant women have been vaccinated before they knew they were pregnant.

When you are vaccinated, you should avoid getting pregnant for at least 1 month afterwards. If you are planning a pregnancy, ask your midwife or doctor whether you need to be vaccinated against chickenpox first.

For some people, the rash may not be too bad, but for others, it can be extremely itchy and uncomfortable. Treatment is to lessen the symptoms and support your body's immune system to do the rest.

Chickenpox can be very itchy so do try to distract your children from scratching as best you can. Scratching can cause infection and scarring.

• Applying a soothing cream (emollient) such as Alpha Keri or fatty cream may help soothe the itch. Calamine lotion can dry the skin too much.
• To prevent dehydration, make sure your child has plenty of clear fluids (water, thin soup or ice blocks; avoid fruit juice). 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 and make sure that their hands and fingernails are kept clean.
• Use mittens or clean socks on their hands to decrease scratching, especially overnight.
• Dress your child in loose-fitting clothing and change sheets daily.
• Try giving your child a lukewarm bath. Don't use soap as this will irritate their skin. Add 2 cups ground oatmeal or half a cup of baking soda to make the bath 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 help reduce pain and headaches. Make sure you measure children's doses accurately and follow the directions given on the bottle or packaging.
• Antihistamines – if you or your child cannot sleep because of the itch, an antihistamine medication may help. Ask your doctor or pharmacist to help you choose. 
• Antibiotics – chickenpox is caused by a virus, so 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 given to some adolescents and adults to reduce the severity of chickenpox. It should be started within 24 hours of the rash appearing.

You should avoid the following medications

• Aspirin – never give your child or young person aspirin as this may increase the risk of Reye syndrome, which is a rare and serious illness.
• Ibuprofen (Nurofen, Brufen, Fenpaed) – the use of ibuprofen may be associated with more severe skin and soft tissue infections after chickenpox (particularly necrotising fasciitis, a rare infection of the deeper layers of skin).

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 appears 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 very sick with chickenpox, staying at home can be difficult. But 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 against chickenpox is free for children at 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 of catching the virus, but may not be able to have the vaccination themselves, so it's recommended that close contacts of these people be vaccinated. The vaccine is funded for certain high-risk people and/or their close contacts. Read more about the chickenpox vaccine.

Images of chickenpox.

Chickenpox images

Chickenpox rash on a boy's forehead Image credit: Tuomas Lehtinen at FreeDigitalPhotos.net	Chickenpox rash with sores at different stages Image credit: Healthify NZ
Chickenpox rash on a boy's back Image credit: Tuomas Lehtinen at FreeDigitalPhotos.net	Infant with chickenpox. Image credit: 123rf

More images

Chickenpox images(external link)(external link) Dermnet NZ