Eleven things you should know about chickenpox (varicella)
Chickenpox, also called varicella, is a common childhood disease—in developed countries over 90 per cent of people have been exposed to it. It is usually a mild disease, although in adults it can be more serious. A vaccine is available and is now part of the standard immunisation program for Australian children.
1 Chickenpox is caused by the Varicella Zoster Virus.
The varicella zoster virus (VZV) is a member of the herpes virus family. It causes chickenpox (varicella) and shingles (herpes zoster).
Like other herpes viruses, VZV affects both skin and nerves. After an attack of chickenpox, the virus usually lies dormant for the rest of the person’s life, but sometimes becomes active again, causing outbreaks of shingles.
2 Chickenpox is a common childhood disease.
In developed countries, 90 per cent of people have been in contact with the varicella zoster virus. Ninety per cent of chickenpox cases occur in children less than 10 years old.
3 The incubation period of chickenpox is two weeks.
The time between infection and appearance of the rash is about 15 days.
Infected people are contagious before the rash appears, which makes the exact time of contact difficult to identify. For this reason, sometimes the incubation period appears shorter than 15 days.
4 Chickenpox can cause a general illness.
In some cases, the first sign of chickenpox is a general illness with fever and swollen glands. This pre-rash illness is called the prodrome. In young children, it may pass unnoticed. In older children and adults, it is usually more significant. The prodrome usually lasts one to three days before a rash appears.
5 Chickenpox causes a rash.
The rash of chickenpox starts on the trunk, then spreads to the face, arms and legs. The spots go through a series of stages over about a week. They start as pink dots or lumps, turn into small blisters which then become pimple-like, and finally develop crusts or scabs.
The spots usually occur in batches over a few days, so that 3-4 days into the rash, there will be blisters, pustules and crusts all present at the same time.
Chickenpox blisters can develop in the mouth or vagina, where they usually rupture to form ulcers soon after they form.
It usually takes 7-14 days for the rash to heal.
Second attacks are uncommon.
6 The aim of treatment is to relieve symptoms.
Because the condition usually heals by itself without problems, the purpose of treatment is to relieve the symptoms. The recommended treatments are:
- Bed rest
- Paracetamol for fever
- Calamine lotion and lukewarm baths with baking soda to relieve the itchiness of the rash.
- Young children may need to wear mittens to prevent scratching.
- Anti viral drugs may be required in more serious cases (more likely in adults or people with low immune function).
7 The chickenpox rash can cause scars.
Scarring often occurs after chickenpox, especially in older children and adults. The scars are round and “punched-out” in appearance, and are commonly called pock marks. Most pock marks come from spots that were not picked or scratched, and mild cases of chickenpox cause pock marks as often as more severe cases..
8 Chickenpox is highly contagious.
The varicella zoster virus can be passed very easily from one person to another. It is passed on in the air by coughing or sneezing. People with chickenpox are contagious from a couple of days before the rash appears until all the spots have crusted over.
9 Most complications are mild.
Scratching the rash can lead to infection by bacteria, also called secondary infection. This can cause painful areas of raw, moist skin. The treatment is with antibiotics.
Adults with chickenpox sometimes develop a lung inflammation called pneumonitis. This is usually mild but in some cases can cause a cough or difficulty in breathing.
10 Chickenpox during pregnancy can cause serious problems.
If a pregnant woman who has never had chickenpox comes into contact with the varicella zoster virus for the first time, there may be serious complications:
- In early pregnancy (the first three months), the foetus may die, or there may be abnormalities of the limbs, brain, eyes and skin when the baby is born.
- If the woman contracts VZV around the time of birth, the baby may contract varicella, which is especially severe in newborn babies. Even with treatment, there is a high death rate
11 Chickenpox can be prevented by vaccination.
Vaccination against chickenpox is effective and recommended for children from 12 months to 12 years.
Adults who are not immune (i.e. never had chickenpox) should consider vaccination if they are in one of the following groups:
- Workers in high-risk occupations (e.g. health workers, child care workers)
- Women intending to become pregnant
- Contacts of people with damaged immune systems
The vaccination is given in a single dose for children and two doses for adults. It is part of the standard immunisation schedule for Australian children and is available free of charge for children born after 1 May 2004.
