Chickenpox

About chickenpox#

Chickenpox (also known as varicella) is a highly infectious viral infection caused by the varicella-zoster virus. It usually causes mild illness, but it can reappear later in life as shingles.

Some people are at increased risk of serious illness, including newborn babies, pregnant women and people with a weakened immune system. Anyone who has not had chickenpox or been vaccinated against it can become infected.

Symptoms#

Symptoms of chickenpox usually appear within 2 to 3 weeks after exposure to the virus. They can include:

• A skin rash
• Low-grade fever
• Headache
• Runny nose
• Sore throat
• Feeling generally unwell

The rash usually begins with small lumps that turn into blisters, which burst and eventually scab over after about 5 days. It can affect the body, limbs and head, including the mouth, eyelids or genital area. The rash is usually itchy and can lead to scarring.

Most people with chickenpox have a mild, self-limiting illness, especially those who have been vaccinated. Chickenpox tends to be more severe in adults than in children. Some people develop serious illness with complications such as:

• Cellulitis – infection and inflammation of the skin
• Pneumonia – infection and inflammation of the lungs
• Hepatitis – inflammation of the liver
• Encephalitis – inflammation of the brain

Very rarely, chickenpox can be fatal.

Chickenpox and shingles#

People who have previously had chickenpox can develop shingles later in life. After causing chickenpox, the virus becomes inactive in the nerve cells of the body, and when it reactivates it can cause shingles.

Symptoms of shingles include a painful rash that blisters. Antiviral medication and pain relief may be needed for treatment. Around one in three adults who have had chickenpox will develop shingles in their lifetime, and the frequency and severity of shingles increase with age.

People with shingles should avoid contact with others, especially those at increased risk of serious illness from chickenpox. Someone who is not immune to chickenpox can become infected with chickenpox (not shingles) if they come into contact with the fluid in the blisters of a person who has shingles.

How chickenpox spreads#

Chickenpox is spread from person to person by:

• Breathing in tiny droplets containing the virus that an infected person breathes out, for example when coughing or sneezing
• Touching the fluid in the blisters of an infected person

Blisters that have scabbed over do not spread infection. People with chickenpox are infectious from 2 days before the rash appears until all the blisters have scabbed over.

Chickenpox in pregnancy#

Most pregnant women are immune to chickenpox. However, some can become infected and develop serious illness, with complications that can include pneumonia, hepatitis and encephalitis.

Chickenpox during pregnancy can lead to abnormalities in the baby, including those affecting the skin, arms and legs, eyes, brain and potentially other parts of the body. The risk is highest during the first 20 weeks of pregnancy. There is also a risk of the newborn baby developing chickenpox and other complications.

If you are planning a pregnancy, speak to your doctor to review your vaccination status and check your immunity with a blood test. If you are not immune and not pregnant, you should be vaccinated before becoming pregnant. Two doses of chickenpox vaccine are recommended, given at least 4 weeks apart.

Pregnant women cannot receive the chickenpox vaccine. If you are pregnant and not immune, avoid contact with people who have chickenpox. If you are exposed, contact your doctor, midwife or hospital as soon as possible, as an injection of varicella-zoster immunoglobulin (VZIG) may be recommended.

Diagnosis#

Chickenpox is usually diagnosed by a doctor. Laboratory testing of a sample of blister fluid can help confirm the diagnosis, and a blood test can be done to check for immunity.

Treatment#

For most people, chickenpox causes a mild illness that gets better without specific treatment. You can relieve symptoms and help prevent complications by:

• Resting
• Drinking plenty of fluids to prevent dehydration
• Using paracetamol (acetaminophen) to bring down fever
• Using creams or lotions such as calamine to reduce itching
• Having colloidal oatmeal baths, which may also help reduce itching
• Wearing mittens to prevent scratching – these can be worn by babies and young children

If you have a skin condition such as eczema, ask your doctor or pharmacist about other suitable creams. People with serious illness may need antiviral medication and hospital admission.

People with chickenpox should avoid contact with others, particularly those at increased risk of serious illness, such as newborn babies, pregnant women and people with a weakened immune system. Parents, guardians or carers should inform the school, kindergarten or childcare center, as testing and treatment may be recommended for staff and other children.

Prevention through vaccination#

Chickenpox can be prevented through vaccination, which helps protect against infection and serious illness. In many countries, the chickenpox (varicella-containing) vaccine is part of routine childhood immunization, often given as a combination MMRV (measles, mumps, rubella and varicella) vaccine. The MMRV vaccine can be given safely to children who have already had chickenpox.

Two doses of vaccine are recommended, given at least 4 weeks apart. Immunized children who still catch chickenpox (known as breakthrough chickenpox) generally have a much milder illness, with fewer skin lesions, a lower fever and a quicker recovery.

Adolescents and adults are also recommended to have two doses given at least 4 weeks apart. The combination MMRV vaccine is generally not recommended for older adolescents and adults. People who have previously had chickenpox or whose blood tests show evidence of immunity may not need vaccination.

People who work in healthcare, childhood education and childcare, or long-term care facilities are strongly recommended to have two doses of chickenpox vaccine if they are not immune. For further information, see your doctor or immunization provider.

Protecting our community#

High levels of vaccination in the community can prevent the spread of chickenpox and protect people who cannot be vaccinated, such as those who are too young or too unwell. This is called herd immunity.

Children with chickenpox must not go to school, kindergarten or childcare until all the blisters have dried and scabbed over. You can look after your own family and protect vulnerable people in your community by:

• Keeping children with chickenpox home from school, kindergarten or childcare until all blisters have scabbed over
• Making sure you and your family are fully vaccinated
• Avoiding contact with others if you or a family member has chickenpox or shingles, particularly those at increased risk of serious illness

People who are exposed to chickenpox and are not immune may be offered treatment to reduce their risk of infection and serious illness, such as:

• Vaccination within 5 days of exposure
• An injection of varicella-zoster immunoglobulin (VZIG) for people at increased risk of serious illness, usually within 4 days (96 hours) of exposure, but sometimes given as late as 10 days afterwards

Key points#

• Chickenpox (also known as varicella) is a highly infectious viral infection caused by the varicella-zoster virus.
• Newborn babies, pregnant women and people with a weakened immune system are at increased risk of serious illness.
• Anyone who has not had chickenpox or been vaccinated against it is at risk of infection.
• Symptoms of chickenpox can appear within 2 to 3 weeks after exposure to the virus.
• The main symptom is an itchy skin rash, often with fever and feeling generally unwell.

Where to get help#