Definition Chicken pox is a disease caused by the varicella-zoster virus (VZV). It is characterised by a blistery rash.
What is going on in the body? Chicken pox is characterised by an itchy rash that looks like very small blisters on a red base. The blisters look like dewdrops on top of a red pimple. It is usually acquired in childhood by inhaling the virus from an infected person. It is also acquired by touching the blisters of the chicken pox rash when there is still fluid in them. The disease is usually more severe in adolescents and adults. It can be life threatening in people with autoimmune problems, pregnant women, and babies born to mothers who have chicken pox around the time of delivery. A foetus can sometimes acquire VZV in the first 6 months of pregnancy. If this happens, the baby can be born with:
scarring of the skin
malformed arms or legs
problems with the central nervous system
eye problems
VZV remains in the body forever. After recovery from chicken pox, the virus usually remains 'latent' or quiet. But sometimes the virus becomes active again causing shingles, which is a painful infection along nerves. The first sign is a rash, which evolves into blisters. After 2 to 3 weeks the blisters become scabs and disappear.
What are the signs and symptoms of the disease? Symptoms usually appear a little more than 2 weeks after exposure, although anywhere between 10 and 21 days is normal. They include:
blistery, itchy rash
rash is usually on all body surfaces, but usually starts on the head and back
fever
The most common complication of chicken pox is bacterial infection, such as cellulitis, of the skin. The virus can sometimes cause pneumonia, inflammation of the liver, and an infection of the central nervous system.
A doctor should be contacted if any of the following symptoms develop:
difficulty awaking
trouble walking
stiff neck
breathing difficulty
vomiting
red, tender skin
a child who looks or acts very sick
fever lasting over 4 days
scabs that become soft and drain a yellow pus
What are the causes and risks of the disease? This highly contagious disease is caused by the varicella-zoster virus. VZV is a member of the herpes virus family.
Chicken pox is a serious disease for adults, people with autoimmune problems, and newborns whose mothers had chicken pox right around the time of delivery.
What can be done to prevent the disease? A vaccine is available for children and adults who have not had chicken pox. The vaccine is routinely recommended for all children, except those with autoimmune problems. The vaccine is strongly recommended for adolescents and adults who have never had chicken pox. People at high risk for severe chicken pox should be given varicella-zoster immune globulin.
How is the disease diagnosed? Chicken pox is usually diagnosed based on the appearance of the rash. However, VZV can be detected and/or cultured from chicken pox blisters during the first few days of the rash. The person's blood can be tested to determine whether he has had chicken pox in the past.
What are the long-term effects of the disease? The most common long-term effect is scarring of the skin. Normal chicken pox can leave temporary marks on the skin that take 6-12 months to fade.
What are the risks to others? If a person has VZV it can be highly contagious to a person who has not had VZV. The contagious period begins about 2 days before the rash develops. The person is generally contagious as long as the blisters have fluid in them, or until the blisters crust over.
What are the treatments for the disease? Acyclovir is used to treat complicated or more severe cases of varicella. It is not routinely used to treat mild to moderate cases in healthy children.
Home care suggestions are designed to treat the symptoms. These include:
Paracetamol to treat fever over 38 degrees Celsius and discomfort. Aspirin should be avoided in a person with chicken pox because of a link between aspirin, chicken pox and a serious infection called Reyes syndrome.
Cool, tepid baths. A cool or lukewarm bath with 1/2 cup of baking soda or oatmeal added to it, will decrease itching from the rash. It may help to have a few baths a day for the first few days of the rash.
Calamine lotion may help reduce itching from the rash. Avoid Caladryl lotion as this may produce unwanted side effects.
Some doctors recommend oral diphenhydamine for itching. This is an antihistamine medication. Check with a doctor for any questions regarding diphenhydramine.
For chicken pox sores in the mouth offer a soft diet and cool fluids. Avoid salty or citrus foods.
For infants and young children it may be necessary to cover the hands with gloves or socks to avoid scratching. Scratching can cause secondary infection of the scabs.
What are the side effects of the treatments? Acyclovir has few side effects. When receiving high-dose acyclovir intravenously however, people can sometimes have kidney toxicity, or damage to the kidneys.
What happens after treatment for the disease? Most people recover without serious long-term effects. But the virus remains and may reactivate at any time to cause shingles.
How is the disease monitored? No further monitoring is needed once a person recovers from VZV. If VZV symptoms redevelop, such as shingles, a person should contact his or her doctor.
Author: Danielle Zerr, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 6/1/2005 Contributors Potential conflict of interest information for reviewers available on request
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