What is chickenpox?

Chickenpox is an infection which ais caused by the herpes varicella virus. When you have chickenpox, your immune system makes antibodies. You are then immune from further chickenpox infection for the rest of your life.

However, the virus remains dormant in your body. It can, in some people, reappear later in life to cause a localised rash called shingles.

Most people have chickenpox as a child. However, it occurs in a small number of adults who missed it as a child. If you get chickenpox as an adult, the infection is usually more severe than in children, and complications are more common, particularly if you are pregnant.

What does 'contact with chickenpox or shingles' mean?

The virus which causes chickenpox and shingles is very infectious. It spreads in the air from person to person. If you are not immune to this virus, you stand a good chance of catching it if:

• you are in the same room as someone with these infections for more than 15 minutes, or
• you have any 'face to face' contact, such as a conversation.

Chickenpox is infectious from 2-4 days before, until 7 days after the rash starts. So, for example, if you talked to someone yesterday who developed the chickenpox rash today, you are at risk of developing chickenpox if you are not immune. Generally speaking patients are not given fit to fly certificates during that period.

Shingles is infectious from the onset of the rash until all the scabs have crusted.

What can I do if I am pregnant and been in contact with chickenpox or shingles?

• If you have had chickenpox in the past, you are immune. You are not at risk, and you do not need to do anything. (About 17 in 20 pregnant women have already had chickenpox as a child and are immune.)
• If you have not had chickenpox, or you are not sure, see a doctor as soon as possible. A blood test may be advised which can detect antibodies. (About 3 in 20 pregnant women have not previously had chickenpox.)

Why is is important to avoid chickenpox during pregnancy?

• For the mother
• Chickenpox can be a severe and unpleasant illness when you are pregnant, even without complications.
• In addition, about 1 in 10 pregnant women who have chickenpox develop inflamed lungs (pneumonia or pneumonitis). This is sometimes serious.
• Inflammation of the brain (encephalitis) is an uncommon but serious complication.
• For the unborn child
• If you have chickenpox within the first 20 weeks of pregnancy there is about a 1 in 50 chance of the baby having an abnormality. The risk is highest if you have chickenpox between the 13th and 20th week.
• If you have chickenpox after the 20th week of pregnancy, there does not appear to be any risk of abnormality to the baby. However, if you have chickenpox in the 4 weeks before giving birth, or within a week after giving birth, your new-born baby may develop a severe form of chickenpox.