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Chickenpox (also known as varicella) is an acute viral illness. It is a common childhood infection that can be prevented by vaccination. It is highly contagious, but rarely serious for most children.

Cause

Varicella-zoster virus, a member of the herpesvirus family.

Symptoms

Mild fever and generalized skin rash that begins on the chest, back, underarms, neck, and face. It starts out as red bumps. Within several hours, the bumps turn into small blisters (fluid-filled bumps), and then scabs after a few days. The sores commonly occur in batches with different stages (bumps, blisters, and sores) present at the same time.

Chickenpox can be severe in newborns, adults, those with weakened immune systems, and susceptible pregnant women (those who have not had chickenpox in the past or varicella vaccine). Complications that commonly lead to hospitalization and can lead to death include severe skin and soft tissue infections, pneumonia, encephalitis, and dehydration.

Spread

From person to person by touching the blister fluid or secretions from the nose or mouth of a person with chickenpox, and by inhalation of aerosols from the blister fluid of skin lesions. Varicella-zoster virus can also spread through the air, when a person with chickenpox coughs or sneezes, tiny droplets with virus and another person breathes them in (airborne spread). Can be spread by contact with the lesions of someone with uncovered shingles (see shingles fact sheet).

Incubation

It takes from 10 to 21 days, usually 14 to 16 days, after being exposed until symptoms develop.

Contagious Period

From 1 to 2 days before the rash begins until all blisters have become scabs (generally within 5 days with a range of 4 to 7 days after the appearance of the first blisters in an otherwise healthy child). Persons who have progressive varicella (development of new lesions greater than 7 days) and persons with altered immunity might be contagious longer.

Diagnosis

Breakthrough disease is a varicella infection that develops more than 42 days after vaccination, which typically is mild with less than 50 skin lesions, low or no fever, and shorter (4 to 6 days) duration of illness. People with breakthrough varicella are just as contagious as unvaccinated people with the disease.

Treatment

Based on typical symptoms and the characteristic rash. Occasionally lab tests are done to confirm chickenpox.

Exclusion

Recommend parents/guardians call their healthcare provider.

Do not give aspirin or other salicylate-containing medications to any child or adolescent under 18 years of age.

Child Care and School: Until all the blisters have dried into scabs; usually by day 6 after the rash began.

It takes 10 to 14 days after receiving vaccine to develop immunity. Vaccine failures occasionally occur. The incubation period is 10 to 21 days. Therefore, exclude children who:

• Appear to have chickenpox regardless of whether or not they have received varicella vaccine, or
• Develop blisters within 10 to 21 days after vaccination.

Chickenpox can occur even if someone has had the varicella vaccine. These are referred to as “breakthrough infections” and are usually less severe and have an atypical presentation. Bumps rather than blisters may be present; therefore, scabs may not be present. These cases should be excluded until all bumps/blisters/scabs (sores) have faded and no new sores have occurred within a 24-hour period, whichever is later. Sores do not need to be completely resolved.

Although extremely rare, the vaccine virus has been transmitted to susceptible contacts by vaccine recipients who develop a rash following vaccination.

Therefore, exclude vaccine recipients who develop a rash after receiving varicella vaccine, using the above criteria.

Exposed children without symptoms do not need to stay home unless chickenpox develops.

Prevention/Control

• All children should be routinely vaccinated with two doses of varicella vaccine; with the first dose at age 12 to15 months and the second dose typically at 4 to 6 years of age.
• If you think a child has chickenpox, have the parent/guardian call their healthcare provider before taking the child into a healthcare facility.
• Cover nose and mouth with a tissue when coughing or sneezing or cough/sneeze into your sleeve. Dispose of used tissues.
• Regular and thorough handwashing is the best way to prevent the spread of communicable diseases. Wash hands thoroughly with soap and warm running water after contact with secretions from the nose or mouth or blister fluid.
• Clean and sanitize mouthed objects and surfaces. Clean and disinfect objects and surfaces contaminated with secretions from the nose or mouth and/or blister fluid at least daily and when soiled. 
• Susceptible persons (those who have not had chickenpox or varicella vaccine in the past) who have been exposed to someone with chickenpox should call their healthcare provider immediately. This is especially important for pregnant women and persons with a weakened immune system. A health care provider may recommend post-exposure prophylaxis based on the timeframe for exposure and other factors. Getting varicella vaccine within 3 days, and possibly up to 5 days, of exposure may prevent disease in these people. Antiviral medicine may also be prescribed.

For more information, call the Missouri Department of Health and Senior Services (MDHSS) Bureau of Communicable Disease Control and Prevention at 573-751-6113 or 800-392-0272 (24/7), or call your local health department.

Chickenpox Parent Fact Sheet

Your child may have been exposed to:

Chickenpox

Chickenpox is a viral illness. It is common for children to get chickenpox. It may be prevented by vaccination.

If you think your child has Chickenpox:

• Tell your child care provider or call the school.
• Need to stay home?
  • Child Care and School:
    Yes, until all the blisters have dried into scabs (this is usually by day 6 after the rash began) or, in vaccinated children who have a mild infection with no crusts, once no new lesions have appeared for at least 24 hours.

DO NOT give aspirin or salicylate-containing medicines to anyone under 18 years of age.

Symptoms

Your child will have a rash that begins as red bumps and may have a fever.

If your child is infected, it may take 10 to 21 days for symptoms to begin.

Spread

• By touching the blister fluid or secretions from the nose or mouth of a person with chickenpox.
• By coughing or sneezing.

Contagious Period

From 1 to 2 days before the rash begins until all blisters have become scabs. Scabs usually form within 6 days.

Call your Healthcare Provider

If someone in your home:

• develops a rash with fever. Your doctor will decide if treatment is needed. DO NOT go to a healthcare facility without calling first. You will be separated from others to prevent spread of illness.
• has been exposed to chickenpox and they have not had chickenpox disease or chickenpox (varicella) vaccine in the past or are pregnant.

Prevention

• In Missouri, all children 12 months and older attending child care or school must be vaccinated with varicella vaccine, have a history of disease, or have an exemption.
• Cover nose and mouth when sneezing or coughing. Use a tissue or your sleeve. Dispose of used tissues.
• Wash hands after touching anything that could be contaminated with secretions from the nose and mouth. Your child may need help with handwashing.
• Clean and disinfect any objects or surfaces that come in contact with secretions from the nose or mouth. Use a product that kills viruses.

For more information, call the Missouri Department of Health and Senior Services (MDHSS) Bureau of Communicable Disease Control and Prevention at 573-751-6113 or 800-392-0272 (24/7), or call your local health department.