Chickenpox (also known as varicella) is usually a mild infection caused by a virus that most children will catch between 2 and 8 years of age. The antibodies produced by the child’s immune system to fight the infection usually provide life-long protection against the virus. It is extremely rare for a person to develop chickenpox more than once. For those few people who do not catch chickenpox as a young child but get it later in life as adolescents or adults, chickenpox can be far more severe and there is a risk of developing serious complications.
Chickenpox is a highly infectious disease caused by a virus called the varicella zoster virus. The virus is spread in tiny droplets of saliva or nasal secretions when a person infected with the virus coughs or sneezes. It takes between two to three weeks to develop the infection after being in contact with an infected person. The person who catches the disease will develop a red blistery rash and is himself or herself infectious for about 1 week, starting about 2 days before a rash develops and remaining infectious for a further 5 to 6 days until the last blister crusts over.
Chickenpox is particularly common in winter and spring, and most children will have caught the disease by the time they reach 8 years of age.
Symptoms of chickenpox tend to be more severe in adolescents than they are in younger children. Symptoms include a high temperature, headache, cough and/or sore throat. A rash, made up of red watery blisters or spots called vesicles, appears on the face and scalp, spreading to the trunk and abdomen of the body and eventually to the limbs, the mouth, vagina or penis. The number of spots varies. Some children have a few isolated spots, others develop crops of spots that are so numerous they can merge into one another so that almost the whole of the body is covered. Three or four days after the vesicles appear they dry and scab over, only to be followed by new vesicles. The chickenpox spots are very itchy, but the spots will not scar unless scratched and broken.
Some older children and adolescents may be at risk of developing complications. Those who are particularly ‘at-risk’ include:
- pregnant girls
- children with a weak immune system such as those with leukaemia, HIV or AIDS
- children taking corticosteroids or drugs called immunosuppressants to treat conditions such as rheumatoid arthritis
- children receiving cancer chemotherapy or radiotherapy
- children who have had an organ transplant or a bone marrow transplant
- children with heart and lung problems
These complications may include pneumonia, inflammation of the brain (encephalitis), inflammation of the kidneys (nephritis), the heart (myocarditis) or liver (hepatitis). Although these complications are rare they can be very serious. Anybody in the ‘at-risk’ group who has got chickenpox or who has been in contact with someone who has chickenpox should be seen by their doctor as soon as possible.
Medicines
Treatment is not usually necessary for chickenpox, but there are a number of ways to ease symptoms. Paracetamol can be used to lower temperature and ease pain. Aspirin must not be given to children under 16 years of age. Calamine lotion can be applied directly to the rash to reduce irritation, or an antihistamine can be taken in the form of tablets or a liquid if the itch is particularly severe. Bathing in cool water may also help ease discomfort.
Chickenpox vaccine
There is a chickenpox vaccine licensed in the UK but it is not part of the routine childhood vaccination programme. If the chickenpox vaccine was included in the childhood vaccination programme, it is feared that there would be a greater number of adults who would develop shingles later in life. This is because adults who have had chickenpox as a child are less likely to have shingles in later life if they have been exposed occasionally to the chickenpox virus. This is because the exposure acts to boost the person’s natural antibody levels. (See separate article on Shingles)
The chickenpox vaccine is not recommended for those whose immune system is not working properly. The vaccine contains the live chickenpox virus and there is a risk of it causing the disease if it is given to someone with an ineffective immune system. The vaccine is also not recommended in pregnancy, because the effects of the vaccine on the developing baby are unknown.
The chickenpox vaccine can though be used before a period of planned or possible future immunosuppression, for example for children awaiting organ transplantation and for children in remission from malignant disease if they have not had chickenpox before. The vaccine will cause the production of antibodies and will guard against the risk of catching chickenpox in the future.
The vaccine is also sometimes given to the healthy brothers and sisters of children with leukaemia or who have had an organ transplant or a bone marrow transplant to prevent them passing on the virus to their brother or sister who is ill.
Talk to your pharmacist if you think that your child may have chickenpox. Your pharmacist will be able to confirm the illness.
If your child has a fever or if the rash is painful, your pharmacist will be able to recommend medicines to reduce your child’s high temperature and ease pain. If the rash is causing a lot of discomfort the pharmacist will recommend calamine lotion to be applied directly to the rash or, depending on the age of your child, may recommend an antihistamine to take.
Always tell your pharmacist your child’s age, and if your child is taking any other medicines or has any other illnesses.
Chickenpox can be very dangerous for people with a lowered immune system as they may go on to develop pneumonia or encephalitis. If your child has recently received corticosteroids or chemotherapy, or has a disease of the immune system, such as leukaemia or HIV seek urgent medical advice if your child might have been in contact with someone with chickenpox or shingles.
Although it can be difficult to tell, if you think any of the chickenpox spots has become infected, see your doctor
