WISCONSIN DIVISION OF PUBLIC HEALTH
Department of Health and Family Services
Chickenpox
(Varicella zoster)
Disease Fact Sheet Series

What is chickenpox?
Chickenpox is a highly communicable disease caused by the Varicella virus, a member of the herpes virus family.

Who gets chickenpox?
Almost everyone gets chickenpox. In metropolitan communities, about 75 percent of the population has had chickenpox by age 15 and at least 90 percent by young adulthood. In temperate climates, chickenpox occurs most frequently in winter and early spring.

How is chickenpox spread?
Chickenpox is highly contagious. Chickenpox is transmitted to others by direct person-to-person contact, by droplet or airborne spread of discharges from an infected person's nose and throat or indirectly through articles freshly soiled by discharges from the infected person's lesions. The scabs themselves are not considered infectious.

What are the symptoms of chickenpox?
Initial symptoms include sudden onset of slight fever and feeling tired and weak. An itchy blister-like rash soon follows. The blisters (vesicles) eventually dry, crust over and form scabs. The blisters tend to be more common on covered than on exposed parts of the body. They may appear on the scalp, armpits, trunk, and even on the eyelids and in the mouth. Mild or inapparent infections occasionally occur in children. The disease is usually more serious in adults than in children.

How soon do symptoms appear?
Symptoms commonly appear 13-17 days after exposure with a range of 11-21 days after exposure.

When and for how long is a person able to spread chickenpox?
A person is usually able to transmit chickenpox from 1 to 2 days before the onset of the rash to six days after the appearance of the first lesion. Contagiousness may be prolonged in people with altered immunity.

Does past infection with chickenpox make a person immune?
Chickenpox generally results in lifelong immunity. However, this infection may remain hidden and recur years later as herpes zoster (shingles) in a proportion of older adults and sometimes in children.

What are the complications associated with chickenpox?
Reye syndrome has been a potentially serious complication associated with clinical chickenpox. For this reason, children with chicken pox should not be treated with aspirin, which may increase the risk of Reye syndrome. Newborn children (less than one month old) whose mothers are not immune and patients with leukemia may suffer severe, prolonged or fatal chickenpox.

Is there a vaccine for chickenpox?*
Yes, a chickenpox vaccine (varicella vaccine) was licensed in the U.S. in 1995.  At first one dose was recommended for children 12 to 18 months and two doses were recommended for children age 13 and older who never came down with chickenpox. 

In August 2006 the recommendations changed as follows:

• Routine: Children who have never had chickenpox should get 2 doses of chickenpox vaccine at these ages:  1st Dose – 12 to 15 months of age and 2nd Dose – 4 to 6 years of age (may be given earlier if at least 3 months after the 1st dose)
• People 13 years of age and older (who have never had chickenpox or received chickenpox vaccine) should get two shots at least 28 days apart
• Catch-up: Children or adolescents who are not fully vaccinated should receive one or two doses of chickenpox vaccine.  The timing of these doses depends on the person's age.  Ask your health care provider

What can a person or community do to prevent the spread of chickenpox?*
The best method to prevent further spread of chickenpox is for people infected with the disease to remain home and avoid exposing others who are susceptible. Persons with chickenpox should remain home (not go to day care, school, or work) until one week after the skin eruption began or until the rash is dry and crusted over.
It is important that those who are sick with chickenpox avoid contact with non-immune newborns and persons with weakened immune systems. These people can have serious complications from chickenpox.

DEVELOPED BY THE DIVISION OF PUBLIC HEALTH, BUREAU OF COMMUNICABLE DISEASE
COMMUNICABLE DISEASE EPIDEMIOLOGY SECTION
PPH 42035 (Rev. 05/04)

*REVISED BY THE WAUKESHA COUNTY PUBLIC HEALTH DIVISION
JANUARY 2007

For More Information Please Call
262-896-8430

PH-OPEN\CD\Fact sheets\chickenpox disease fact sheet revised 1-07.doc