Chickenpox Fact Sheet

Chickenpox is caused by a virus called varicella-zoster

Chickenpox is a highly contagious disease that is spread from person to person by touching the blisters, saliva, or mucus of an infected person, or from virus spread through the air. A person can spread chickenpox from 1 to 2 days before the rash appears until all the blisters have formed crusts (usually about 5 days).

Symptoms start 10 to 21 days after exposure to the virus and include fever, tiredness, and an itchy rash with small blisters that dry up and form scabs within 5 days. More severe but rare problems that could occur are pneumonia (especially in adults), skin infection, blood infection, or brain involvement (encephalitis). If there are any signs of infection such as redness, warmth, swelling on the skin, or if a fever persists or comes back after it has gone away, check with your doctor. Always call your doctor's office before visiting so that other patients can be protected if necessary.

Most people get chickenpox when they are young

Approximately 90% of chickenpox cases occur in children 1 to 14 years of age, and 90% of people have had chickenpox by their early 20's. The disease is usually mild, and not life threatening in otherwise healthy children, but can be more serious in newborn babies and in adults.

Some people are at risk of serious complications from chickenpox

The unborn fetus of a pregnant woman who develops chickenpox
A newborn baby whose mother had an onset of chickenpox 5 days before to 2 days after delivery
Any person with a weakened immune system, including people with cancer, organ transplant patients, and HIV
Any person who acquires chickenpox as an adult

Children under 18 with chickenpox should not take salicylates (aspirin) or aspirin-containing products because of the risk of Reye syndrome. Instead, use medication which contains acetaminophen (for example, Tylenol or Tempra) to treat fever.

Prevent chickenpox infection with varicella vaccine. Vaccine is recommended for:

All healthy children 12 to 18 months of age (one dose of vaccine)
Children 19 months to 12 years of age who have not had chickenpox (one dose of vaccine)
Persons 13 years of age and older who have not had chickenpox and are at high risk for exposure (for example, living in a household with children; teachers; institutional residents and staff; college students; or international travelers); or persons who have close contact with persons at high risk for complications from chickenpox (2 doses of vaccine, 4 to 8 weeks apart)

Prevent the spread

If you have chickenpox, stay away from others until the blisters are dry and crusted. Persons with chickenpox should not attend school or child care until the blisters are dry and crusted. In 6 to 10% of children who receive the varicella vaccine, a mild rash may develop within 5 to 26 days after immunization; these children may still attend school or child care.
Premature infants, immunocompromised persons, or pregnant women may need a shot of VZIG (varicella-zoster immune globulin) to prevent chickenpox after exposure. Check with your doctor for further details.
Persons of any age who have never had chickenpox should receive varicella vaccine within 3 to 5 days of exposure to reduce the risk of developing chickenpox.

Pregnant women exposed to chickenpox need to be individually evaluated by a doctor

Pregnant women who have not had chickenpox should inform their doctors if they have symptoms of chickenpox and/or of any contact with a person who has chickenpox.

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Maryland Department of Health & Mental Hygiene — Epidemiology & Disease Control Program
May 2002