Chickenpox is a very common and highly contagious disease. Although
the symptoms can be annoying and uncomfortable and limit normal
activities, the disease is usually mild and rarely serious. In
otherwise healthy children, chickenpox lasts two weeks or less
and does not cause complications. In adults, newborn babies, and
children with weakened immune systems, however, it can be a serious,
Chickenpox is caused by a type of herpesvirus called varicella-zoster
virus (VZV). After the initial chickenpox infection, VZV hides
in nerve cells and is sometimes reactivated later in life. This
reactivated, often very painful, disease is called herpes zoster
or shingles. Researchers are trying to learn what causes the virus
to become active again after being dormant for such a long period
Chickenpox epidemics can occur anytime of the year, but usually
in late winter and early spring. Doctors estimate that each year
3.5 to 4 million people, mostly children, get chickenpox. Ninety
percent of cases are in people under 15 years of age.
Symptoms And Diagnosis
The signs and symptoms of chickenpox include a rash with round
or oval red sores, fever, tiredness, and loss of appetite. In
children, fever and rash usually occur at the same time. Fever
can range from 100°F
and last for three to five days. The rash may be mild and barely
noticeable or severe and accompanied by intense itching. Often,
the intensity and extent of the rash increase as the disease spreads
from child to child within a family. Although the rash can involve
the entire body, it typically is found on the back, chest, face,
A doctor can easily diagnose chickenpox by examining the characteristic
rash, with healed and unhealed sores on the body, and by noting
the presence of other symptoms mentioned above.
It is virtually impossible for a susceptible person to avoid getting
chickenpox. It is highly contagious and spreads quickly in settings
like day-care facilities and schools and within families. The
virus is transmitted by direct contact with the rash on an infected
person or by droplets dispersed into the air by coughing or sneezing.
The time between exposure to the virus and the development of
symptoms is usually about two weeks, but can range from 10 to
20 days. A person can transmit the disease for up to 48 hours
before the telltale rash of chickenpox appears. The period of
transmission lasts for four to five days after the rash begins
until the sores have crusted over. Therefore, staying away from
someone only after they have visible signs of chickenpox is probably
too late to prevent transmission.
Unless the infection is severe, children with chickenpox usually
are not treated.
Scratching can make the lesions harder to heal and cause scarring.
The doctor may recommend anti-itch drugs, such as over-the-counter
antihistamines, to control this troublesome symptom. Warm baths
with uncooked oatmeal or cornstarch added also can help relieve
Proper hygiene is the best way to prevent bacterial skin infections.
One way to prevent a child from getting a skin infection from
scratching is to keep the fingernails clean and cut short.
Fever can be reduced with acetaminophen. Aspirin should not
be taken by anyone with chickenpox because it can lead to a serious
disease called Reye syndrome. Cool baths also can help bring down
Acyclovir (Zovirax) is an antiviral drug that attacks the virus.
When treatment is started very soon after the first sores appear,
it shortens the duration of rash formation by about one day and
reduces the number of new sores. The American Academy of Pediatrics
recommends it for use in premature babies, adolescents, adults,
and other high-risk populations.
Recently, the Food and Drug Administration licensed a vaccine
to prevent chickenpox in people who have not been infected. The
American Academy of Pediatrics recommends that a single dose of
the vaccine be given routinely to children ages 12 to 18 months
and to children 18 months to 12 years old who have not had chickenpox.
They also recommend that adolescents and adults who have not had
chickenpox receive two injections of the vaccine.
Future studies of the vaccine will try to determine how long protection
from the vaccine lasts and if a booster will be needed.
Because chickenpox most often is an uncomplicated infection, it
ordinarily does not require a visit to the doctor.
It is wise, however, to visit a doctor if symptoms other than
the rash, low fever, and fatigue are present. Symptoms that require
immediate medical attention are fever of more than °F,
dizziness, rapid heartbeat, shortness of breath, tremors, loss
of muscle coordination, vomiting, and/or stiff neck.
If the lesions become infected with bacteria such as staphylococcus
or streptococcus, a doctor can prescribe an appropriate antibiotic.
In children and adults whose immune systems are impaired by disease
or suppressed by drugs (including steroids), chickenpox can affect
internal organs. Also, people with impaired immune systems are
more likely to develop bacterial skin infections, and their sores
take longer to heal. In children with leukemia, chickenpox can
be life threatening.
Infrequently, chickenpox can cause central nervous system complications
of which the most serious is encephalitis (inflammation of the
brain). Encephalitis can be life threatening in adults and usually
lasts for a minimum of two weeks. Of those patients who survive,
15 percent continue to have neurologic symptoms after the initial
infection has cleared. Other nervous system complications include
meningitis and Reye syndrome.
Another serious complication, which occurs mainly in adults, is
varicella pneumonitis (inflammation of the lungs). This complication
can be life threatening to women during the second or third trimester
If a pregnant woman develops chickenpox five days before or up
to 48 hours after delivery, the baby can be born with complications
from the infection. Serious disease in the newborn, however, is
uncommon. A pregnant woman who is not immune to chickenpox and
has a prolonged exposure to a person with the disease should consult
with her physician about the risk to herself and her unborn child.
For information about shingles (herpes zoster) contact:
National Institute of Neurological Disorders and Stroke
31 Center Drive, MSC 2540
Bethesda, MD 20892-2540
NIAID, a component of the National Institutes of
Health (NIH), supports research on AIDS, tuberculosis and other
infectious diseases as well as allergies and immunology. NIH is
an agency of the U.S. Public Health Service, U.S. Department of
Health and Human Services.
Office of Communications
National Institute of Allergy and Infectious Diseases
National Institutes of Health
Bethesda, MD 20892
Public Health Service
U.S. Department of Health and Human Services