CENTERS FOR DISEASE CONTROL AND PREVENTION Date Last Rev'd: March 9, 1995
CHICKEN POX (VARICELLA) DISEASE INFO
Chickenpox is a common, highly contagious disease of childhood. Most Americans will have been infected by the virus by age 15, and it is estimated that approximately 4 million cases occur each year. Children between 5 and 9 years of age account for the majority of all cases, with more cases occurring during the winter and spring than during other times of the year.
Chickenpox is easily transmitted between household members or classmates at schools or day-care centers through the drainage from the open sores, respiratory droplets, or airborne particles. The virus can also be transmitted indirectly through contact with articles containing fresh drainage from the sores. Persons are most contagious from 1 to 2 days before the rash appears through the first 5 to 6 days after the rash. Generally, patients are no longer contagious after the sores have crusted over.
Persons exposed to chickenpox are most likely to develop symptoms 14 to 16 days after exposure. However, for normal individuals, symptoms may appear any time after 10 days and up to 21 days.
Chickenpox is characterized by 1 to 2 days of fever up to 102 degrees, general body weakness, and a rash, which in many children is the first sign of the disease. Only rarely will a person have chickenpox without a rash. Often, the rash begins on the scalp, moves to the trunk, and then to the arms and legs.
The chickenpox rash usually is generalized, itchy, and progresses to blisters, which become open sores before crusting. The blisters contain a clear fluid that can transmit the virus to others. Successive crops of blisters appear over several days.
In normal children, chickenpox is generally a mild disease although the following complications do occur. Sometimes bacterial skin infections will develop from the open sores associated with chickenpox. Other complications that are more rare but serious include pneumonia, infection of the brain (encephalitis), infections of the covering of the brain (meningitis), Reye syndrome, and death.
Serious chickenpox disease and complications are more likely to occur in the following types of patients:
- Those whose immune systems are not functioning normally, such as persons with certain leukemias or cancers, persons with AIDS, or persons taking drugs, including steroids, which suppress their immune systems;
- Newborn infants whose mother developed the chickenpox rash close to the time of delivery; and
- To a lesser degree, normal adults.
After a chickenpox infection, persons generally have lifelong immunity to chickenpox and do not have a second episode of chickenpox. However, the virus can reactivate later in life as a different problem - zoster or shingles. This is particularly likely to happen if a person has a problem with their immune system such as can occur with older age, disease, or drugs.
CHICKEN POX (VARICELLA) - PREGNANCY AND INFANTS
More than 90% of the adult U.S. population is immune to chickenpox because of an infection during childhood. Therefore, for the vast majority of pregnant women, being exposed to chickenpox should pose little concern to either the pregnant woman or the unborn child.
Pregnant women who are not immune to chickenpox, and who have been significantly exposed may be at increased risk. Both the pregnant woman and the unborn child have risks including:
- A pregnant woman has an increased risk of complications associated with a chickenpox illness. However, remember that while chickenpox is usually a mild infection with few complications for normal children, for normal adults the infection can be more severe, and complications are a little more frequent. Therefore, normal adults, including pregnant women, may have an infection with symptoms somewhat more severe than children, and these adults are also at increased risk of complications.
Pregnant women who are not immune to chickenpox and who have significant exposure to a person with chickenpox can be evaluated by their doctor for possible treatment with Varicella-Zoster Immune Globulin, also known as VZIG. Treatment with VZIG, if given within 96 hours of exposure, can prevent or moderate a chickenpox infection in the pregnant women. There is, however, no evidence that VZIG can prevent or moderate a chickenpox infection in the unborn child. A treatment dose of VZIG costs between $400 and $500 and physicians can obtain VZIG from The American Red Cross.
2. The unborn child is at a low risk of birth defects if the pregnant woman
is infected with chickenpox during the first 16 weeks of pregnancy. Infants whose mother was infected with chickenpox during the first 16 weeks of pregnancy rarely develop congenital varicella syndrome, which can include eye, skin, or limb defects in the child. The risk of having congenital varicella is low (around 2 to 3 percent), and is similar to the risk of developing birth defects in general. Unborn children whose mother is infected with chickenpox after the first 16 weeks do not appear to develop congenital varicella syndrome.
3. The newborn child is at increased risk of serious infection if the
pregnant woman is infected with chickenpox close to the time of delivery. If the mother develops chickenpox between 5 days before delivery and 48 hours after delivery, the newborn infant may develop serious infection. Infants whose mothers develop chickenpox outside the "5 days before to 48 hours after delivery" window do not appear to be at increased risk of serious illness.
4. Premature infants who have significant exposure after birth may be at
increased risk for serious illness, especially those infants born before 28 weeks of gestation, or whose mothers are not immune to chickenpox.
If there is concern that a pregnant woman has been exposed to chicken pox, there are 3 ways to figure out if she ia already immune to chickenpox: 1. By asking her parents or relatives if they remember whether she had
chickenpox.
2. Check the medical records of her family or pediatric physician.
3. Have a laboratory test performed that would indicate whether she was
already infected and thus is immune.
If the pregnant woman is not known to be immune to chickenpox, it is important to figure out whether she was significantly exposed to a person with chickenpox. Significant exposure means being in the presence or having prolonged contact with someone who is developing or currently has a chickenpox infection. For example, significant exposure to chickenpox can include:
(a)continuous household contact.
(b)playmate contact of greater than one hour.
(c)hospital contact involving the same bedroom, or adjacent beds in a
large ward, or
(d)prolonged face-to-face contact.
If a woman is pregnant and had a significant exposure to chickenpox, she should consult with her physician about the risk to herself and her unborn child.
CHICKEN POX (VARICELLA) - EXPOSED
Since 3 to 4 million cases of chickenpox occur each year, exposure is very difficult to prevent, especially in children. More than 90% of the adult U.S. population are already immune to chickenpox because they were infected during childhood. Therefore, for the vast majority of normal adults, being exposed to chickenpox should pose little or no concern.
For a person to become infected with chickenpox, they must be both susceptible to infection (that is, not immune) and have significant exposure to an infected person.
Individuals who want to know if they have had chickenpox can do one of the following:
- Ask relatives if anyone remembers them having chickenpox.
- Check the medical records of their family or pediatric physician.
- Have a laboratory test performed that would indicate whether they have been infected previously and therefore are immune.
Significant exposure to chickenpox can include:
(a)continuous household contact.
(b)playmate contact of greater than one hour.
(c)hospital contact involving the same bedroom, or adjacent beds in a
large ward or
(d) prolonged face-to-face contact.
Remember that chickenpox is a mild infection with few complications in normal children. However, certain groups of people are at greater risk for more serious infection and complications. These groups include the following: highrisk newborn infants, which are those newborn infants whose mother developed chickenpox between 5 days before delivery to 48 hours after delivery, and persons with a defective immune system, such as cancer and leukemia patients, persons with AIDS, or persons taking drugs, including steroids, which suppress their immune system. Normal adults are at a greater risk of developing serious illness or complications, than children, but most do not have serious illness.
Complications of chickenpox include skin infections, pneumonia, brain inflammations, infections of other body organs, Reye syndrome, and death. Because Reye syndrome, a serious brain and liver disease, may occur after using aspirin during an episode of chicken pox or flu, aspirin is not recommended for treatment of symptoms of chickenpox or flu. In fact, never give aspirin to children without first consulting a physician.
There is currently no licensed vaccine for chickenpox in the United States. Persons at high risk of serious chickenpox illness who are not immune to chickenpox should be evaluated by their doctor for treatment with VaricellaZoster Immune Globulin, also known as VZIG, if they have significant exposure to infection. In some cases, treatment with VZIG, if given within 96 hours of exposure, can prevent or moderate a chickenpox infection. A treatment dose of VZIG costs between $400 and $500 and physicians can obtain VZIG from The American Red Cross. There is no evidence that VZIG can prevent or moderate a chickenpox infection in an unborn child.
CHICKEN POX (VARICELLA) - VZIG (Varicella-Zoster Immune Globulin)
Varicella-Zoster Immune Globulin, also know as VZIG, can be used to modify or prevent chickenpox in susceptible individuals who have had recent significant exposure to the disease. To be effective, VZIG should be administered within 96 hours of exposure. Treatment with VZIG may lengthen the incubation period of chickenpox to as long as 28 days.
VZIG is normally used to treat individuals who have a high risk of serious disease or complications, including immunocompromised children, high risk newborn children, premature infants with significant exposure, and immunocompromised adults. Normal adults, including pregnant women, should be evaluated on a case by case basis. Because there is no evidence that VZIG can prevent or modify a chickenpox infection in the unborn child, the decision to administer VZIG to a pregnant woman is based on the benefits to the woman alone.
The duration of protection after VZIG administration is unknown, but VZIG is probably effective for at lease three weeks. VZIG is not known to be useful in treating clinical chickenpox or shingles after the infection has developed, or in preventing disseminated shingles, and VZIG is not recommended for these uses.
VZIG costs between $400 and $500 for an adult dose. It is available from the American Red Cross through its regional offices.
CHICKEN POX (VARICELLA) - PREVENTION
Because chickenpox is highly contagious even before symptoms appear, prevention is difficult. Susceptible persons who have been exposed to chickenpox and may be developing the disease should be kept from contact with persons at high risk for serious chickenpox infection, such as patients with defective immune systems, from 10 days until 21 days after exposure. Isolating infected persons for 1 week after eruption of sores is prudent and somewhat effective in limiting the spread of chickenpox.
Varicella-Zoster Immune Globulin, also know as VZIG, can be used to prevent or modify chickenpox in susceptible individuals with significant exposure to the disease. Ordinarily, VZIG is reserved for use with persons who are at high risk for serious chickenpox disease or complications. To be effective VZIG should be administered within 96 hours of exposure. Persons who develop mild chickenpox after receipt of VZIG may still be infectious.
A vaccine to prevent chickenpox has been developed by Merck Sharp Dohme Research Laboratories and is being tested for use in normal children and adults; it may become available within a couple of years.
TREATMENT
Once a person develops chickenpox, treatment may include bedrest and medication for fever, headache, and itching. Your local physician familiar with your child is best suited to recommend treatment for chickenpox. In all cases, contact your physician before using any treatment because some preparations are harmful if not used in the correct dose, especially in children. Remember that aspirin should not be given to children to control fever, pain, or headache associated with chickenpox. In fact, never give aspirin to children without first consulting a physician. Instead, acetaminophen products (like Tylenol), may be used to treat mild complaints. Also, do not use skin treatments containing diphenhydramine without first consulting a physician.
Acyclovir and Arabinoside-A are antiviral drugs used to treat individuals with serious chickenpox disease and complications. These drugs are sometimes used to treat patients with defective immune systems and high-risk newborn infants. These drugs are not usually used to treat chickenpox in normal healthy children with a routine chickenpox illness.
CHICKEN POX (VARICELLA) - STATISTICS
Chickenpox is a common, highly contagious disease of childhood that occurs usually during late winter and early spring. Most Americans will have been infected by the virus by age 15, and it is estimated that approximately 3.5 to 4 million cases occur each year. Not all states require that health care workers report chickenpox cases. Some cases of chickenpox are so mild that medical attention is never sought. Therefore, only an average of 225,000 cases of chickenpox are reported to the CDC annually. Even though most cases of chickenpox are mild with few complications, between 40 and 90 chickenpoxrelated deaths occur annually. About half these deaths occur in normal individuals, and half in persons whose immune systems are not functioning normally. A few other deaths are from Reye Syndrome, which can occur in children following the use of aspirin during an episode of chickenpox. During the past few years, the deaths due to chickenpox have been decreasing. The decrease in the death rate may be due to both improved treatment and to a decrease in Reye Syndrome.
