Chickenpox is an infection caused by the varicella-zoster virus. Most children have chickenpox at some stage. Most commonly, children get chickenpox before the age of 10. 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.
- High temperature (fever), aches and headache often start a day or so before a rash appears.
- Spots (rash). Spots appear in crops. They develop into small blisters and are itchy. They can be anywhere on the body. Some children may be covered in spots; others have only a few or even none. The rash starts off looking like red spots, which then blister, and then scab over.
- Loss of appetite or feeding problems.
- chickenpox scabbing
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.
- If badly scratched the spots may cause scarring
- Some spots become infected with germs (bacteria) in some cases. This is the most common complication in children. If this occurs, the surrounding skin becomes red and sore. Antibiotics in the form of creams or medicine may then be needed.
- Inflammation of the lung (pneumonia) and inflammation of the brain (encephalitis) are rare complications.
Although serious complications are rare, it is best to be watchful. A doctor should be consulted if a child develops any worrying symptoms such as:
- Breathing problems.
- Weakness such as a child becoming wobbly on his/her feet.
- Fits (convulsions).
- 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 is a much 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 local band-like 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 having had chickenpox. Some virus particles remain inactive in the nerve roots next to the 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.
Note: Chickenpox can be caught by people who have not had chicken pox before if they are exposed to a person with shingles. However, shingles cannot be caught from a person with chickenpox or shingles.
Treatment for chickenpox
For most children
Treatment is mainly aimed at easing symptoms and trying to make the child as comfortable as possible whilst the immune system deals with the virus:
- A fever commonly occurs with chickenpox, and may make the child feel uncomfortable and irritable. The following are things may bring the temperature down and make the child feel more comfortable:
- Paracetamol to lower a temperature. Note: paracetamol does not treat the cause of the fever. It merely helps to ease discomfort. It also eases headaches, and aches and pains. Paracetamol is not required if the child is comfortable and not distressed by the fever, aches or pains.
- If the child is still distressed by a fever despite paracetamol, ibuprofen may also be used. BUT only if really needed and if paracetamol has not worked. Ibuprofen should not be used for children known to be allergic to ibuprofen or children with asthma.
- Any extra layers of clothes should be taken off the child if the room is normal room temperature. It is wrong to wrap up a feverish child. The aim is to prevent overheating or shivering.
- The child should be given lots to drink. This helps to prevent a lack of fluid in the body (dehydration). You might find that a child is more willing to have a good drink if they are not so irritable. So, if they are not keen to drink, it may help to give some paracetamol first. Then, try the child with drinks half an hour or so later when his/her temperature is likely to have come down.
- 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.
- Dress children comfortably so they are not cold or overheated. Use cool smooth fabrics such as cotton.
- A soothing cream (emollient) may help the itch. Calamine lotion is the one most used, although it is not known how effective it is.
- A sedating antihistamine (in a tablet or liquid medicine) may help with sleep if itch is a problem. This can be used in children over 1 year old. The dose should be given at bedtime. Chlorphenamine (Piriton®) is the one most used.
- Fingernails should be cut short to stop deep scratching.
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 vaccination. If a child has not already had chickenpox and is in one in the following groups, a doctor should be seen urgently if they have contact with chickenpox, or have symptoms of it:
- Children (babies) less than 1 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 1 month and under 12 years who develop chickenpox.
A person with chickenpox is very infectious. The virus spreads in the air from person to person. Nine in ten people who have not had chickenpox would catch it after being in the same room as someone with chickenpox for more than 15 minutes; or having any face-to-face conversation with someone with chickenpox.
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 spots first appear until they have all crusted over (commonly about five days after onset of the rash). A child with chickenpox should stay off school for five days from the onset of the rash. Also, whilst infectious, they should keep away from at-risk people who may develop 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 having 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 all the spots have crusted over.
Vaccination against chickenpox
A vaccine that protects against the virus that causes chickenpox is available.