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 unapparent 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 was licensed in the U.S. in 1995 and is recommended for children 12 to 18 months of age and older children who have not had chickenpox. Recipients of the vaccine should not receive aspirin for 6 weeks after the vaccination.

To protect high-risk newborns and persons with weakened immune systems following exposure, a shot of varicella zoster immune globulin (VZIG) is effective in modifying or preventing disease if given within 96 hours after exposure to a case of chickenpox.

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. If they develop symptoms, they should remain home until one week after the skin eruption began or until the lesions become dry.

Avoiding exposure of non-immune newborns and patients with weakened immune systems to chickenpox is important.

Last Revised: June 22, 2011