If you would like to know about chicken pox symptoms and diagnosis, and the implications of contact with chicken pox, the following information will interest you.
What are chickenpox and shingles?
Chickenpox and shingles are infections which are caused by the varicella-zoster virus. (Other pages give details about these two conditions.) 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. It occurs in a small number of adults who missed it as a child. If you get chickenpox as an adult, the illness 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?
Chickenpox
A person with chickenpox is very infectious. The virus spreads in the air from person to person. If you have not already had chickenpox, you stand a good chance of catching it if:
- you are in the same room as someone with chickenpox for more than 15 minutes, or
- you have any 'face to face' contact with someone with chickenpox, such as a conversation.
Chickenpox is infectious from 2-4 days before the rash first appears until all the spots have crusted over (commonly about 5-6 days after the onset of the illness). 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 already immune.
Shingles
Shingles is caused by the same virus as chickenpox. It is infectious from the onset of the rash until all the scabs have crusted. However, unlike chickenpox, a person with shingles does not cough the virus out. The virus is just shed from the rash on the skin. Most people with shingles have a rash on their chest or abdomen and it is usually covered by clothes or dressings.
So, you are not likely to catch chickenpox from someone with shingles if their rash is covered. Some people have shingles on exposed skin such as the face which will be more infectious than if the rash is covered. Therefore, it is difficult to give definite rules about contact with someone with shingles. If in doubt, discuss any contact with your doctor.
What can I do if I am pregnant and been in contact with chickenpox or shingles?
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If you have had chickenpox in the past, you will be immune. You are not at risk, and you do not need to do anything. (About 9 in 10 pregnant women have already had chickenpox as a child and are immune.)
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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 1 in 10 pregnant women have not previously had chickenpox.)
What is the blood test?
The blood test checks for antibodies to the chickenpox virus.
- If you have antibodies in your blood, this means you have had chickenpox in the past. No further action is then needed.
- If you do not have any antibodies then you are at risk of developing chickenpox.
What can I do if I have no antibodies?
You can be given an injection of immunoglobulin which may stop chickenpox from developing. The immunoglobulin contains antibodies to the chickenpox virus. It is best given within four days of coming into contact with the virus. However, there may be some protection even if you are given immunoglobulin up to 10 days after contact with the virus. (It takes between 11 and 20 days for the chickenpox illness to develop after coming in contact with an infected person. This is the 'incubation period'.)
Why is it important to avoid chickenpox during pregnancy?
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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.
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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 within seven days before or after giving birth, your new-born baby may develop a severe form of chickenpox.
What if I develop chickenpox when I am pregnant?
Most pregnant women who have chickenpox recover fully and their baby is fine. However, as discussed above, the illness tends to be unpleasant and there is some risk of complications. Another page called 'Chickenpox in Adults' gives details of the infection.
See a doctor urgently if you suspect that you have chickenpox when you are pregnant, or within seven days of giving birth. Antiviral medication is an option to treat it, but it must be started within 24 hours of the rash appearing to be of benefit. It is normally only advised if you are more than 20 weeks pregnant. It does not cure the illness, but tends to make it less severe. (Also, a newborn baby at risk of severe chickenpox can be given immunoglobulin.)
In summary - when you are pregnant:
- If you have not had chickenpox in the past (or are not sure) then see a doctor urgently if you come into contact with a person with chickenpox or shingles.
- Avoid people with chickenpox or shingles.
- If you do get chickenpox, you are likely to make a full recovery, but complications occur in some cases.
©EMIS and PIP 2006
