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Chickenpox

What is chickenpox?

Chickenpox is a highly contagious disease caused by the varicella-zoster virus, a member of the herpes virus family. It is the most commonly reported childhood disease. As of 1995, chickenpox is no longer required to be reported to the New York City Department of Health.

Who gets chickenpox?

Before the availability of the chickenpox vaccine, almost everyone got chickenpox. In metropolitan communities, about 75% of the population had chickenpox by age 15 and at least 90 percent by young adulthood.

The incidence of chickenpox, as well as chickenpox-related hospitalizations, has decreased significantly since implementation of the national vaccination program in 1995. In temperate climates, chickenpox occurs most frequently in the winter and early spring.

How is chickenpox spread?

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 an 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. These are soon followed by an itchy blister-like rash. The blisters 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 month. Mild or inapparent infections occasionally occur in children. The disease is usually more serious in adults than in children.

How soon after infection do symptoms appear?

The average incubation period for chickenpox is 14 to 16 days after exposure, with a range of 10 to 21 days.

When and for how long is a person able to spread chickenpox?

A person is able to transmit chickenpox1 to 2 days before the onset of rashes until all the chickenpox lesion have crusted (scabbed). Contagiousness may be prolonged in people with impaired 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 older adults and sometimes in children.

What are the complications associated with chickenpox?

Reye's Syndrome is a potentially serious complication associated with chickenpox. Newborn children (less than one month old) whose mothers are not immune, and patients with leukemia may suffer severe, prolonged or fatal chickenpox. Immunodeficient patients and those on immunosuppressive drugs may have an increased risk of developing a severe form of shingles.

Is there a treatment for chickenpox?

In 1992, acyclovir was approved by the U.S. Food and Drug Administration for treatment of chickenpox in healthy children. However, because chickenpox tends to be mild in healthy children, most physicians do not feel that it is necessary to prescribe acyclovir.

Is there a vaccine for chickenpox?

A vaccine to protect children against chickenpox was first licensed in March 1995. It has been recommended for children aged 12 months or older. Older children and adults who have previously had chickenpox do not need to be vaccinated. Contact your doctor for further information about the chickenpox vaccine.

What can be done 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. Persons with chickenpox should avoid unnecessary exposure of non-immune newborns and immunodeficient patients. If high-risk newborns and immunodeficient patients are exposed to chickenpox, a dose of varicella zoster immune globulin (VZIG) is effective in modifying or preventing the disease as long as it is given within 96 hours after exposure.

CDC's chickenpox web page