Family doctor

Overview:

• Chickenpox is highly contagious and 90 percent of children will get it
• It is usually a mild illness in children but can be severe in adults
• The illness is spread by direct contact or coughing and sneezing
• The incubation period is between 10 to 21 days
• A person will be contagious two days before the itchy sores appear
• The sores look like pimples at first but then blister and eventually crust over and heal
• Chickenpox is contagious until the blisters have scabbed about a week later
• A vaccine is available for children to prevent the illness
• Chickenpox will lie dormant in the body after recovery and cause shingles later in life

What is it?

Chickenpox is caused by a virus (same family as herpes) and almost everyone gets the illness before they become adults.

It is highly contagious but is usually a mild illness. However, it can be severe in babies, adults and those with weak immune systems.

The virus is spread by direct contact, or coughing and sneezing from an infected person.

Chickenpox epidemics usually occur in late winter or early spring. Millions of people catch chickenpox each year, and 90 percent of sufferers will be under 15 years.

The incubation period is 10 to 21 days after contact with a carrier. A person is contagious two days before the chickenpox rash appears.

After recovery from chickenpox the virus remains dormant in nerve cells and can be reactivated during adulthood, causing a painful illness called shingles or herpes zoster.

Babies born to women who got chickenpox within five days before and 48 hours after delivery could develop complications from the infection, however, this is rare.

What are the symptoms?

A chickenpox rash is generally the first sign of illness. The rash is characterised by itchy round or oval sores which at first look like pimples but will later blister and then crust over and heal.

The sores are normally found on the back, chest, stomach and face, but can cover the whole body.

The illness may cause a fever, particularly in adults who are more likely to feel a lot sicker than children.

Other symptoms include tiredness and loss of appetite.

The illness lasts for about a week to 10 days and patients are contagious for about one week after the rash breaks out. Sufferers will need to be isolated during that period.

Possible complications include bacterial skin infections, scarring, pneumonia and in rare cases meningitis and brain inflammation (encephalitis).

Seek medical advice if the patient runs a high fever, experiences dizziness, a rapid heart beat, breathlessness, tremors, vomiting or a stiff neck.

What can be done to help?

Children are normally not treated but need to be kept home from day care and school until their sores have crusted over.

They should rest in bed until they feel better. Children should be urged not to scratch the sores because that could cause scarring.

Cut children's fingernails to help prevent a skin infection.

Anti-itch medicine available from pharmacies may be helpful (e.g. an antihistamine). A warm bath with half a cup of sodium bicarbonate may also relieve the itch.

Fever can be treated with paracetamol. Avoid aspirin because in rare cases this can cause a severe reaction.

The drug treatment, acycolvir, is available in some countries to treat people at high risk of complications, such as those with a weak immune system. The medicine will shorten the illness and prevent new spots from forming.

A form of immune globulin, Varicella zoster immune globulin, can be given to people who have been in contact with the virus and who are at high-risk of developing complications, like pregnant women, premature infants and those with a weak immune system.

How can it be prevented?

A person who has had chickenpox is immune for life, however, they can develop shingles later in life.

A vaccine has been available since 1995 and is recommended for healthy children over nine months.

The Varilrix vaccine is effective in protecting children against a severe chickenpox attack. Only 3.6 percent of vaccinated children will get a mild case of chickenpox.

A blood test will confirm whether a child is already immune and does not need to be vaccinated.

It takes about two weeks after an injection of Varilrix for a child to become fully immunised against chickenpox. The vaccine is believed to be effective for at least 20 years.

Future trends

Researchers are also studying the virus to establish why it can lie dormant for decades and then be reactivated in the shingles form.

Scientists are also studying how long the Varilrix vaccine protects against the illness.

Getting help

Your doctor, practice nurse, or pharmacist will be able to help.