What is chickenpox?
Chickenpox, caused by the varicella-zoster virus (VZV) is a highly contagious disease occurring in adolescents and adults, but most commonly in children. It is a member of the herpes family of viruses. After the illness, the chickenpox virus remains in the body and may reactivate in later years as shingles.
What are the symptoms?
A person with chickenpox usually develops a fever over 37.7°C and feels tired and unwell. Red spots appear that turn into blister-like sores and then scab over. The rash can be very itchy and may appear in one or more successive “crops”.
How is chickenpox spread?
Chickenpox is spread from person to person by:
- droplet, airborne spread or direct contact with secretions from the mouth and nose of a person with chickenpox or from the sores of someone with chickenpox or shingles
- indirect contact with articles freshly soiled with secretions from the mouth and nose of a person with chickenpox , or with secretions from the sores of someone with chickenpox or shingles.
The only way to stop the spread of the virus from person to person is to stop infected people from sharing the same room, which may not be practical.
What is the incubation period?
Two to three weeks after exposure, commonly 14 to 16 days.
What is the period of communicability?
As long as 5 days, but usually 1 to 2 days before the onset of the rash, continuing until all the lesions are crusted. Usually, this is about 5 days after the rash develops.
Who is likely to get the disease?
Anyone who has not had chickenpox is susceptible. Usually, once a person has had chickenpox, he or she will become immune. Very rarely does a second attack occur.
Who is at risk for complications?
Newborns, and people whose immunity is suppressed for any reason (e.g. disease, medication, or cancer treatment), can become very ill with chickenpox. A pregnant woman who is not immune, and her unborn baby, are at risk for complications if the mother contracts chickenpox during her pregnancy.
How do I know if I am immune?
The disease is very common, so most adults have had it. Any person who has a definite history of chickenpox may be considered immune. When there is no such history, contact your family physician.
Chickenpox Vaccine
A vaccine against chickenpox is available in Canada. Contact your doctor, or Public Health, if you need information about chickenpox vaccination. The best way to prevent chickenpox in children is vaccination.
What else should I do?
If you and/or your child are/is ill with chickenpox:
- Avoid contact with pregnant women or people whose immunity is suppressed.
- Notify your child’s school or daycare. Chickenpox is a reportable disease and Public Health must be notified.
- Keep your child home from school or daycare until he or she is well and able to participate normally in all activities. Chickenpox is contagious from 2 days before the rash appears, and is most infectious from 12 to 24 hours before the rash appears, so it is easy to spread it to others without realizing it. It spreads through the air, not just by direct contact with the rash. Children need time to recover. Children with chickenpox may get pneumonia, skin infections or infections of the brain (encephalitis). Because of the open areas in the skin, individuals with chickenpox have a higher risk of developing severe bacterial infections such as flesh-eating disease, a severe form of group A streptococci.
- Do not give medications containing acetylsalicylic acid (ASA). It is safe to use medications containing acetaminophen to control fever. Check with the pharmacist when buying over-the-counter medication.
- Separating a child who is ill with chickenpox from other children within the household will usually not prevent infection.
- Applying calamine lotion to the rash may help reduce itching.
If you and/or your child are/is exposed to chickenpox and have/has not had chickenpox in the past:
- Contact you doctor if anyone in the household has reduced immunity due to disease, medication, or cancer treatment.
- Contact your doctor if you are pregnant.
What are shingles?
After infection with chickenpox, the virus remains in the body. If the chickenpox virus reactivates the person may develop shingles. This occurs more commonly in the elderly and in people whose immunity is compromised. You can catch chickenpox from someone with shingles through contact with their saliva or their skin rash. People who have shingles remain infectious to people who have not had chickenpox for up to a week after the appearance of their sores. You cannot get shingles from someone with chickenpox.
References
- Canadian Pediatric Society of Canada, Chickenpox, July 2008.
- Durham Region Health Department, Chickenpox, October 2006.
- Heymann, D. L., (2008). Control of Communicable Diseases Manual (19th Ed.). Washington, DC: American Public Health Association.
- Ministry of Health & Long-Term Care, Infectious Disease Protocol, 2009.
