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What is chickenpox?

Chickenpox on an adult's back

© F malan, CC BY-SA 3.0, via Wikimedia Commons

The chickenpox infection is caused by the varicella-zoster virus (VZV). The immune system makes proteins called antibodies during the infection. These fight the virus and then provide lifelong protection against it (immunity). Therefore, it is uncommon to have more than one bout of chickenpox in a lifetime.

Most people have chickenpox as a child. Most children get chickenpox before the age of 10 years. About 9 in 10 people have had it by the age of 15 years. It is uncommon for adults to have chickenpox.

What are the symptoms of chickenpox in adults?

Chickenpox symptoms are usually more severe in adults than in children. Expect to have a few uncomfortable days.

High temperature (fever), aches and headache

This will often start a day or so before a rash starts.

Spots (a rash)

Spots appear in crops. The spots develop into small blisters and are itchy. They can be anywhere on the body and sometimes also in the mouth. Several crops may develop over several days. Some people are covered in spots; others have only a few.

Loss of appetite and tiredness

Feeling sick is common as well. The fever and generally feeling unwell can last several days. The blisters gradually dry up and scab. They slowly fade over a week or so, but may take 2-3 weeks to go completely.

How to treat chickenpox in adults

Treatments to help adult chickenpox symptoms

Adult chickenpox treatments that may ease symptoms whilst your immune system deals with the virus include the following:

• Having plenty to drink to avoid a lack of fluid in the body (dehydration).

• Taking paracetamol to ease high temperature (fever), headaches, and aches and pains. Ibuprofen and other non-steroidal anti-inflammatory drugs should be avoided unless advised by a doctor.

• Soothing creams (emollients) put on the spots (rash) may ease itching. Calamine lotion is the most used, although it is not known how effective it is.

• Antihistamine tablets taken at bedtime may help you to sleep if itch is a problem at night. You can buy these at pharmacies, or get them on prescription.

Antiviral medication for adult chickenpox

Antiviral pills such as aciclovir can limit the severity of chickenpox. These pills do not kill the virus, but stop the virus from multiplying. Adults or teenagers over the age of 14 with chickenpox may be advised to take an antiviral medicine - but only if it can be started within 24 hours of the rash first developing. If it is started after this time it is not likely to have much of an effect. So, if started on time, an antiviral medicine may help to reduce the severity of the illness.

Antiviral medication is especially useful in situations where chickenpox in adults can be more serious. For example, for people who have a poor immune system, for newborn babies and for pregnant women. (Notera: antiviral medication is not normally advised for healthy children who develop chickenpox.)

Is chickenpox dangerous in adults?

• Adults are more likely than children to have complications from chickenpox.

• The spots do not usually scar unless they are badly scratched.

• In some cases of chickenpox, some spots become infected with germs (bacteria). If this occurs, the surrounding skin becomes red and sore. Antibiotic medication may then be needed.

• Inflammation of the lung (pneumonia) is a complication affecting about 1 in 10 adults with chickenpox. People who smoke are more likely to get this.

• Inflammation of the brain (encephalitis) and ataxia (problems co-ordinating movements) are very rare complications.

• Vary rarely, other serious complications develop. For example:

  • Inflammation of heart muscle (myocarditis).

  • Inflammation of the kidneys (glomerulonephritis).

  • Appendicit.

  • Inflammation of the pancreas (pancreatitis).

  • Inflammation of the testes (orchitis).

  • Inflammation of joints (arthritis).

  • Inflammation of various parts of the eye.

Therefore, although serious complications are rare, it is best to be watchful. Seek medical advice if you develop any worrying symptoms that you are unsure about, such as:

• Breathing problems.

• Svaghet.

• Drowsiness.

• Convulsions.

• Pains or headaches which become worse despite paracetamol or ibuprofen.

• Being unable to take fluids, due to a severe rash in the mouth.

• A very severe rash, or a rash which bruises or bleeds into the skin ('haemorrhagic rash').

• Becoming generally more and more unwell.

In general, complications are uncommon. However, some people have a higher risk of developing complications from chickenpox in adults. Anyone in the following groups should see a doctor urgently if they have symptoms of adult chickenpox:

• Pregnant women.

• People with a poor immune system. For example, people with leukemi, with HIV/AIDS, taking steroid medication or having chemotherapy.

• People with heart or lung disease.

• People with severe skin conditions.

• Very young babies - especially those less than 1 month old (neonates).

How do you get shingles?

Shingles is caused by the same virus that causes chickenpox and so is a delayed 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 band-like local area along the affected nerve. About 1 in 5 people have shingles at some time in their lives. 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 the separate leaflet called Shingles (Herpes zoster) for details.

Notera: you can catch chickenpox from being exposed to a person with shingles if you have not had chickenpox yourself. However, you cannot catch shingles from a person with chickenpox, or catch shingles from a person with shingles.

Adult chickenpox and pregnancy

If you are pregnant and have not had chickenpox (or been immunised) and come into contact with a person with chickenpox - see your doctor urgently. Chickenpox can be more serious if you develop chickenpox whilst pregnant. However, a treatment with a product called human varicella-zoster immunoglobulin (VZIG) may prevent chickenpox from developing. See the separate leaflet that deals with this in more detail, called Chickenpox contact in pregnancy.

Is chickenpox in adults contagious?

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; eller

• You have any face-to-face contact with someone with chickenpox, such as a conversation.

Nine in ten people who have not had chickenpox would catch it after being exposed in this way.

It takes between 7 and 21 days (most commonly 10-14 days) to develop symptoms after catching the virus (the incubation period).

Protecting others from adult chickenpox

A person with adult chickenpox is infectious from two days before the rash and spots first appear until they have all crusted over (commonly about five days after the onset of the illness). You can usually return to work after this time if you feel well enough. (A child with chickenpox should stay off school for five days from the onset of the rash.) Whilst you are infectious, keep away from people who have an increased chance of having a severe illness if they get chickenpox. These people are listed above under 'Are there any complications?'.

Healthy people who have not had chickenpox as a child may also want to avoid catching it. So, friends and family who have not had chickenpox may wish avoid you whilst you are infectious. However, most adults and many children have already had chickenpox, and so are immune.

Notera: people with adult chickenpox should not travel by air until the spots have all crusted.

Treatment can also be provided to protect those at high risk of suffering from severe chickenpox and those who may pass on infection to those at high risk (for example, healthcare workers).

Aciclovir for recommended for those at high risk, except neonates, who may be given human varicella-zoster immunoglobulin (VZIG).

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 contact with chickenpox.

  • Report to occupational health before patient contact if you feel unwell or develop a high temperature (fever) or itchy rash.

  • Get immunised against the varicella-zoster virus (chickenpox virus).

Whether you have been exposed to chickenpox or not, if you are a healthcare worker and you have never had chickenpox you should have a test to see if you are immune. If you are not immune you may need to be immunised.

Is there a vaccine against chickenpox in adults?

Yes - there is an effective vaccine (sometimes known as the varicella vaccine) that protects against the virus that causes chickenpox. It has become part of the routine childhood immunisation programme in certain countries such as the United States, 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 special groups. For example, to 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 who are on chemotherapy. The vaccine is widely available privately in the UK.