What is the infectious agent that causes
Chickenpox is caused by the varicella-zoster virus.
The same virus causes both chickenpox (varicella)
and shingles (zoster).
Varicella-zoster virus is a
member of the herpes virus family.
How do people get chickenpox?
Chickenpox spreads from person to person by direct
contact with fluid from broken chickenpox blisters or
through the air by coughing or sneezing.
Chickenpox is so contagious in its early stages that
an exposed person who has not had chickenpox has
a 70 percent to 80 percent chance of getting the disease.
After infection, the virus stays in the body for life.
Although people cannot get chickenpox twice, the
same virus can reactivate and cause shingles, a local
infection of the skin than occurs along nerve
A person with shingles can spread the
virus to an adult or child who has not had
chickenpox, and that person can develop
What are the signs and symptoms of
Chickenpox typically produces a mild fever and an
outbreak of itchy blisters on the scalp, face, and
The blisters dry and become scabs in four to
five days. The blisters occur in successive crops that
can produce hundreds of scabs.
An infected person
is contagious from one to two days before the rash
appears and until all blisters have formed scabs.
How soon after exposure to the virus do
Symptoms usually occur within two to three weeks
after contact with an infected person.
How is chickenpox diagnosed?
Chickenpox is usually diagnosed by the
characteristic signs and symptoms of the disease. A
blood test is available to confirm the diagnosis if
Who is at risk for chickenpox?
Anyone who has not had chickenpox or has not been
immunized against chickenpox is at risk after
exposure to an infected person.
What complications can result from
Although most people recover from chickenpox
uneventfully or with a few minor scars, a small
percentage of people have serious complications.
Each year in the United States, 4,000 to 9,000 people
are hospitalized with chickenpox, and up to 100
Those at highest risk for complications are:
Persons with weakened immune
Although adults make up fewer
than five percent of chickenpox cases in the United
States, they account for half of all deaths from the
Complications of chickenpox include:
Encephalitis (inflammation of the
Chickenpox can also lead to severe problems
in pregnant women, causing:
Infection of the newborn during childbirth
What is the treatment for chickenpox?
Anti-virus medicine is available for treatment, but it
is used mostly in adults and others who are at risk
for developing more serious disease. Keeping blisters clean and not scratching them can prevent
How common is chickenpox?
Almost everyone gets chickenpox by adulthood. In
the United States, chickenpox affects about 4 million
people per year, mostly children. In temperate
climates, most cases occur in the late winter and
How can chickenpox be prevented?
Those infected with chickenpox should avoid
exposing others who might be at risk of getting the
People with symptoms should stay home
until one week after the skin blisters appear or until
the blisters become dry.
A vaccine to protect children against chickenpox was
licensed in 1995.
Two doses of vaccine are recommended for all
children. The first dose should be given at 12 months of age and the second dose at four years of age.
Older children who
have not had chickenpox should receive the vaccine.
Adults who have not had the disease should also be
The vaccine prevents chickenpox in
70 percent to 90 percent of those who receive it.
People who have been immunized but develop the
disease usually experience milder symptoms than
people who have not been vaccinated.
As is the case with all immunizations, there are
important exceptions and special circumstances.
Health care providers should have the most current
information from the Centers for Disease Control
and Prevention about the chickenpox vaccination.
you have any questions about the disease described
above or think that you or a family member might
have chickenpox, consult a health care provider.
Where can I get more information?
Contact your doctor or the Southern Nevada Health District, Office of Epidemiology at (702) 759-1300.