Chickenpox

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Introduction

Chickenpox or varicella (var-ee-sell-ah) is a viral infection caused by the varicella-zoster virus that causes fevers and a blistering rash, usually in children. It is extremely easy to catch from one child to another.

Toddler with crusted haemorrhagic vesicles and papules on back and face from chicken pox (varicella) virus

Who gets it?

Any person can get chickenpox - it affects people of any race, age, or gender. Most often it affects children under 10 years old. For every 10 children who are not immune to the virus (who either has not had the vaccine, or has not had chickenpox infection before), 7 or 8 of them will become infected if they come across someone with the virus in the early stages of the illness. This means chickenpox is extremely easy to catch. People who have a weakened immune system because of medications or a medical illness, pregnant women, and babies under three months old should see a doctor if exposed to the virus because there are medications that can prevent the infection from developing.

Vaccination is the best prevention against chickenpox and complications caused by the illness. In some cases, children who are immunised can still get chickenpox but it is usually a mild version of the infection, with a low fever and few blisters, and it tends to last a shorter time. In Australia, as part of the immunisation schedule, children 18 months old will get the chickenpox vaccine. Vaccination is safe and the most effective way to protect your child from a serious case of the disease. The chickenpox vaccine also protects your child from getting shingles later in their life.

What causes it?

Chickenpox is caused by the varicella-zoster virus. It can be spread by contact with a person who has an active chickenpox infection or shingles, especially by touching the liquid from the blisters, or from the fluid droplets in the air when an infected person coughs or sneezes. A person with chickenpox is most infectious one to two days before the rash appears and up until the last blisters dry up. The rash usually appears 10-21 days after being exposed to someone who had chickenpox. This is called the ‘incubation period’.

What does it look and feel like?

Looks like…

The rash can start on the chest, back, or face and then move to other parts of the body including inside the mouth. The rash appears as a group of small red bumps. These bumps usually get bigger and become blisters filled with fluid. Eventually the blisters pop, and the rash dries up and forms a scab. New bumps can appear at various times over several days. The rash usually lasts about a week.

Feels like…

The chickenpox rash is usually quite itchy and uncomfortable. Your child may also experience other symptoms such as high fever, headache, flu-like symptoms, reduced appetite, vomiting and diarrhoea. Chickenpox is usually more severe in adults, but some children may expereince rare complications such as:

Infection and inflammation of the lung
Inflammation of the brain
Bleeding disorders

What tests might be needed?

The diagnosis can usually be made based on the appearance of the rash and the history. A swab of the fluid from the blister can confirm the diagnosis. If there are more serious complications from the illness, x-rays and blood tests may be done.

What treatments are available?

What can I do?

Most healthy children do not require any specific treatment for chickenpox. Treatment for these children is aimed at reducing the symptoms and discomfort associated with the viral illness, for example:

Paracetamol or ibuprofen can be used to help with fever and irritability.

IMPORTANT: Do NOT use aspirin in children with chickenpox

Calamine lotion, antihistamine tablets, warm baths, and fragrance-free moisturiser can help reduce itch.
Trim your child’s fingernails to reduce scratching and prevent secondary bacterial infections.
For children, it can be difficult to keep hydrated when unwell with a viral illness. To prevent this, give your child small frequent sips of fluids (preferably water), jelly, icy poles, and soup.

Children with chickenpox are highly infectious and so should not go to childcare, kindergarten, or school until the last blister has dried up. Avoid contact with people at risk of chickenpox complications such as pregnant women, babies, or people with a weakened immune system. You should also inform the school if your child gets chickenpox.

Medical therapies

An antiviral medication such as aciclovir (which can be taken as a tablet or an injection) can be used in specific cases, such as for:

Adults
Unvaccinated children older than 12
Children who have long-term lung problems or skin conditions
Children that must take long-term steroid medications or aspirin
Adults or children with a weakened immune system

What happens after treatment?

Most healthy children make a full recovery after chickenpox infection. The rash usually clears up in one to three weeks and scarring is rare. Scars are usually prominent if the rash gets infected with bacteria. After your child's chickenpox infection, the virus stays in their body. Most children who have had chickenpox do not develop chickenpox a second time. However, in some children the virus can resurge later in life causing a disease called ‘shingles’.