What is chickenpox?
Chickenpox is an infection caused by the varicella-zoster virus. Most children have chickenpox at some stage. The immune system makes antibodies during the infection. These fight the virus and then provide lifelong immunity. Therefore, it is rare to have more than one bout of chickenpox in your lifetime.
What are the symptoms of chickenpox?
- Fever (temperature), aches and headache often start a day or so before a rash appears.
- Rash. Spots appear in crops. They develop into small blisters and are itchy. They can be anywhere on the body. Several crops may develop over several days. Some children may be covered in spots; others have only a few or even none.
- Dry cough and sore throat are common.
Some children feel quite unwell for a few days. Others appear only mildly ill. Most are much better within a week. The blisters dry up and scab. They gradually fade, but may take up to two weeks to go completely.
What are the possible complications?
- The spots do not usually scar unless they are badly scratched.
- Some spots become infected with bacteria in about 1 in 10 cases. If this occurs, the surrounding skin becomes red and sore. Antibiotics may then be needed.
- An ear infection develops in about 1 in 20 cases.
- Pneumonia and inflammation of the brain (encephalitis) are rare complications.
- Vary rarely, other serious complications develop. For example:
- Reye’s syndrome.
- Myocarditis (inflammation of the heart muscle).
- Glomerulonephritis (kidney inflammation).
- Hepatitis (inflammation of the liver).
- Pancreatitis (inflammation of the pancreas).
- Henoch-Schönlein purpura (a condition that can affect the kidneys).
- Orchitis (inflammation of the testes).
- Inflammation of various parts of the eye.
Therefore, although serious complications are rare, it is best to be vigilant. See a doctor if your child develops any worrying symptoms that you are unsure about such as:
- Breathing problems.
- Pains or headaches which become worse despite paracetamol.
- Being unable to take fluids, due to a severe rash in the mouth.
- A severe rash, or a rash which bruises or bleeds into the skin (haemorrhagic rash).
- Becoming generally more and more unwell.
Shingles is caused by the same virus that causes chickenpox and so is like a complication of chickenpox. Anyone who has had chickenpox in the past may develop shingles. Shingles is an infection of a nerve and the area of skin supplied by the nerve. It causes a rash and pain in a local band-like area along the affected nerve. About 1 in 5 people has shingles at some time in their life. It can occur at any age, but it is most common in people over the age of 50.
The reason why shingles may occur is because the virus does not completely go after you have chickenpox. Some virus particles remain inactive in the nerve roots next to your spinal cord. They do no harm there, and cause no symptoms. For reasons that are not clear, the virus may begin to multiply again (reactivate). This is often years later. The reactivated virus travels along the nerve to the skin to cause shingles. See separate leaflet called ‘Shingles’ for details.
What is the treatment for chickenpox?
For most children
Treatment is mainly aimed at easing symptoms and trying to make your child as comfortable as possible whilst the immune system deals with the virus:
- Advice on dealing with a fever is detailed below.
- Calamine lotion put on the spots may ease itching.
- Antihistamine tablets or liquid medicine for children over one year old may help with sleep if itch is a problem. Give a dose at bedtime. You can buy these at pharmacies or get them on prescription.
- Keep fingernails cut short to stop deep scratching.
Dealing with a fever
A fever that commonly occurs with chickenpox can make your child feel uncomfortable and irritable. The following are things that you can do that may bring the temperature down and make your child feel more comfortable:
Do not cold-sponge a child who has a fever. This used to be popular, but it is now not advised. This is because the blood vessels under the skin become narrower (constrict) if the water is too cold. This reduces heat loss and can trap heat in deeper parts of the body. The child may then get worse. Many children also find cold-sponging uncomfortable.
Some people use a fan to cool a child. Again, this may not be a good idea if the fanned air is too cold. However, a gentle flow of air in a room which is room temperature may be helpful. Perhaps just open the window or use a fan on the other side of the room to keep the air circulating.
For special at-risk groups
Some children have a higher risk of developing complications from chickenpox. In addition to the above treatments, they may need extra treatment such as aciclovir (an antiviral medicine) or immunoglobulin. If your child has not already had chickenpox and is in one in the following groups, you should see a doctor urgently if they have contact with chickenpox, or have symptoms of it:
- Children (babies) less than one month old.
- Children with a poor immune system. For example, children with leukaemia, immune diseases or HIV/AIDS.
- Children taking certain medication such as steroids, immune suppressing medication or chemotherapy.
- Children with severe heart or lung disease.
- Children with severe skin conditions.
Antiviral medication is also used for adults and teenagers who develop chickenpox, as they too have a higher risk of complications. However, antiviral medication is not normally advised for healthy children aged over one month and under 12 years who develop chickenpox.
Is chickenpox infectious?
A person with chickenpox is very infectious. The virus spreads in the air from person to person. For example, 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.
It takes between 7 and 21 days (most commonly 10-14 days) to develop symptoms after catching the virus (the incubation period).
A person with chickenpox is infectious from two days before the rash first appears until all the spots have crusted over (commonly about five days after onset of the rash). A child with chickenpox should stay off school or nursery for five days from the onset of the rash. Also, whilst infectious, they should keep away from at-risk people who may get a severe illness if they get chickenpox. These include:
- Pregnant women who have not had chickenpox in the past. Chickenpox can be severe and cause complications during pregnancy.
- People with a poorly functioning immune system. For example, people with leukaemia, with HIV/AIDS, on steroid medication, or who are taking chemotherapy.
- The at-risk children listed earlier.
Healthy adults who have not had chickenpox may also want to avoid catching it, as the illness tends to be worse in adults.
Note: people with chickenpox should not travel by air until six days after the last spot appeared.
Are you a healthcare worker?
Healthcare workers come into contact with people with poor immune systems, pregnant women and newborn babies. They should be aware that if they catch chickenpox, they can be infectious for two days before a rash or illness appears, and be a risk to patients. So, if you are a healthcare worker and come into contact with someone who has chickenpox (or who develops it within the next two days), then:
- If you have been immunised against chickenpox, or have definitely had chickenpox in the past, you are likely to be immune. You should continue working, but contact your occupational health department if you feel unwell or develop a rash.
- If you are uncertain about whether you have had chickenpox or been immunised, you should have a test to see if you are immune. If you are not immune you should:
- Avoid contact with high-risk patients for 8-21 days after the contact.
- Report to occupational health before patient contact if you feel unwell or develop a fever or rash.
- Get immunised against the varicella-zoster virus (chickenpox virus).
Is there a vaccine against chickenpox?
Yes, there is a vaccine that protects against the virus that causes chickenpox. It is part of the routine childhood immunisation programme in certain countries such as the USA, Canada and Australia. Currently, there are no plans to make immunisation against chickenpox routine for children in the UK. In the UK, the vaccine is offered by the NHS to certain groups. For example, healthcare workers who are not immune to chickenpox. Also, to people who are not immune to chickenpox and who are in close contact with people with a poor immune system. For example, brothers and sisters of children on chemotherapy.
Should I let my child catch chickenpox?
Some parents encourage their children to mix with others who have chickenpox in order to catch it.
Some arguments for this:
- Chickenpox is usually a milder illness in a child than in an adult.
- The risk of serious complications is higher in adults. In particular, chickenpox during pregnancy can cause serious complications to both mother and baby.
- Most people get chickenpox at some stage. As the risks are fewer if you have it as a child, it may be better to get it over with.
Some arguments against this:
- “I could not willingly let my child develop an illness.”
- Although rare, some children do have serious complications.
Different parents have different views on this issue. And remember, children who develop a chickenpox rash today will have been just as infectious over the previous two days when they were well, but were incubating the virus.
Also note: if someone in the family or home is temporarily at high risk of complications (listed earlier – pregnant women, etc) then it is best to put off deliberately catching it.
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