Chicken pox (Varicella Zoster) is a virus which belongs to the herpes virus family. It is highly contagious and transmitted by respiratory droplets and close personal contact to those who are already infected. The incubation period of chicken pox is 10-20 days from the day of exposure. While the fact that you have been exposed to chicken pox does not absolutely mean that you will get it, it is serious enough if you are pregnant to see your doctor and let him or her know about the exposure AS SOON AS POSSIBLE.
The initial infection with chicken pox is characterized by fever (101 to 103), tiredness and fatigue and a characteristic rash which is very itchy. This characteristic rash develops as a series of red spots which soon become vesicular (blister-like) and finally scab and crust over before healing. The incubation period is 7-21 days and the disease is infectious 1 to 2 days before the rash appears and lasts until all of the vesicles crust over. Characteristically the vesicles form in several waves (or crops) of lesions at 3 to 5 day intervals for up[ to 14 days.
Chickenpox is a common disease of childhood where it causes a mild infection. Over 80% of all adult's are already immune hence will not get chicken pox again. When exposure to chicken pox occurs during pregnancy it can be a great cause of worry. Fortunately, however chicken pox infection is uncommon in pregnant woman occurring in only one out of every 2000 pregnancies. Yet, when it does happen the results can be disastrous.
Chicken pox infection during pregnancy can be associated with three possible outcomes:
1. Maternal Infection: Chicken pox can be more severe in adults and particularly during pregnancy. Varicella Pneumonia can occurs in approximately 10% of cases when it occurs during pregnancy. This pneumonia can become severe enough to end up requiring assisted breathing and up to 6% of women die.
2. Congenital Varicella Syndrome: This condition is secondary to initial chicken pox infection. It occurs primarily in women who are 24 weeks of pregnancy or less. This syndrome affects the developing fetus causing one or more of the following skin scarring; eye defects (smaller than normal eyes, blindness and/or cataracts), deformities of the child's limbs; and neurological abnormalities (microcephaly, cortical atrophy, mental retardation and malfunction of ability to maintain contests of the bowel and bladder).
There may be an increased risk of spontaneous miscarriage The intrauterine diagnosis of congenital Varicella Syndrome can be made by ultrasound. An increased amount of amniotic fluid with increased echos in the area of the liver and problems with the heart, enlargement of spleen and liver and respiratory problems may be seen, when the ultrasound is performed as little as five weeks after the chicken pox infection. There is virtually no congenital abnormalities created if infection occurs after 20 weeks of pregnancy
3. Varicella Infection of the Newborn: The passage of the virus to the fetus appears to increase as the pregnancy advances. At least 50% of all fetuses are infected when maternal infection occurs one to four weeks before delivery and one third of these babies develop clinical chicken pox despite high levels of passive antibody formed by the mother. It takes at least a week for the mother to pass the protective antibodies to her baby, if the baby is born before that time, the baby is at risk of overwhelming infection after birth. In such situations the baby may demonstrate no clinical evidence of chicken pox infections at birth, but then can develop chicken pox during the first three to four weeks of its life. Twenty to thirty percent of all infants will die if the mother's infection occurs between 5 to 7 days before delivery and up to one month days after delivery.
Immunization
Women who are planning to become pregnant and who have not had chicken pox or are at risk. These women should consider immunization with live attenuated chicken pox vaccine which has been shown to be safe and effective in preventing chickenpox prior to pregnancy. If chicken pox vaccine is not available and the mother to be has not had chicken pox, strict avoidance of anyone with chicken, children or adult's, or anyone who have been exposed to chicken pox over one week earlier or less than 21 days, or who experience any unknown rash or open vesicles is strongly recommended.
If You Are Pregnant and You Believe That You Have Been Exposed to Chicken Pox:
It is very important to determine the certainty of your exposure, the stage of infectiousness (vesicular rash or development of rash within 48 hours of contact) and the degree of exposure (household member, face-to-face contact for five minutes or more, or indoors contact for more than one hour).
If you have a previous history of chicken pox it is reasonable to believe that you have some form of immunity to a chicken pox infection. However, if there is any doubt have your doctor determine your Varicella IgG levels to find out whether you are protected or not.
If you have had a significant contact (see #1 above) and you have no history of having had chicken pox, then Varicella IgG level should be checked immediately. At least 85% of women will be positive and can be reassured. You can also save time by asking your doctor to do a varicella titer as part of your prenatal work up.
If you are not immune to varicella and the infection occurs before 24 weeks' gestation, then you should be given Varicella-Zoster Immune Globulin (dosage given is based on age, size and weight) as soon as possible after contact.
Detection of Varicella IgM in your blood indicates a primary chicken pox infection. If you develop primary chicken pox or you show serologic evidence of conversion in the first 24 weeks of pregnancy, then you will likely have a 2% risk of Congenital Varicella Infection and will need to be aware of the implications.
Referral to a specialist for detailed ultrasound examination at 16-24 weeks' gestation or five weeks after infection, whichever is the sooner, should be considered.
Neonatal ophthalmic examination should be performed at birth.
If there is no previous history of chicken pox and the contact occurs after 24 weeks, there is no risk of Congenital Varicella Infection, but the risk of maternal varicella pneumonia remains. In these circumstances the administration of Varicella-Zoster Immune Globulin should be considered, although the evidence to support its use is not strong.
What Should You Do if You Are Already Pregnant and You Develop Chickenpox?
You should immediately isolate yourself from all other pregnant women and newborns.
If you are in the second half of your pregnancy call your doctor immediately...do not go to your doctor's office if you have chicken pox, this can expose other pregnant women and put them at similar risk ... If you can be seen within less than 24 hours after the chicken pox rash breaks out, then you can start the antiviral medication, acyclovir. This may reduce the severity and duration of the illness. There are some risks to your unborn baby when acyclovir is used in the first trimester, however, the risks of congenital deformities caused by chicken pox must also be considered.
If you chicken pox infection occurs five days before or two days after delivery there is a 20%-30% risk of you baby having chicken pox. If at all possible, your delivery should be delayed until 5-7 days after the onset of maternal illness to allow for passive transfer of antibodies from you to your baby.
If your delivery occurs within five days of maternal infection, or if you develop a chicken pox infection within two days of giving birth, then your baby should be given Varicella-Zoster Immune Globulin as soon as it is possible.
If your baby is infected with chicken pox he or she should be treated with acyclovir as soon as is possible.
If you develop any respiratory symptoms, if the lesions are dense and bleed, or if new lesions continue to develop six days or more after their onset, you should be hospitalized and an Infectious Diseases specialist should be consulted immediately.
Varicella pneumonia is an indication for treatment with intravenous acyclovir. In certain circumstances it may be necessary to consider mechanical ventilation. In the third trimester of pregnancy this may be facilitated by delivery, but elective delivery at this time will be associated with a high risk of your baby being exposed to and coming down with chicken pox without adequate immunity.
What Other Considerations Should I Be Concerned With?
On occasion an other child in the home may have chicken pox about the time you and your baby are to come home from the hospital. If you are immune to chicken pox the risk to your new baby is minimal. If you are not already immune, both you and your baby should be given Varicella-Zoster Immune Globulin.
You and your baby (and anyone else in the house who has not had chicken pox) should be isolated from the individual with chicken pox.
Anyone who is thought (or known by previous testing) to be "not immune" should avoid contact with individual who has chicken pox. Those who are exposed, should be tested for varicella antibodies, and if found to be susceptible should be warned they may develop chicken pox. They should be informed that the incubation period is between two and three weeks.
Antibiotics are never prescribed to treat chicken pox infection because it is caused by a virus. Antibiotics may be used, however, if you or your child develop a secondary infection caused by a bacteria.
Chicken pox is treated much the same way it is in children with Tylenol used for the control of any fever, calamine lotion, anesthetic creams and/or Benadryl for control of itching. Aspirin may be used by adults as they are not susceptible to Reye's Syndrom, but should not be used when treating children.
Chicken pox can last longer in adults and may be more problematic with the risk of pneumonia, skin infections with staphylococcus or streptococcus bacteria causing a cellulitis, pitted pox-like scars, and a rare complication (1 in 1000 cases of chicken pox) encephalitis.
Prevention of Varicella Infection with Varecella-Zoster Immune Globulin
If Varicella Immune Globulin (also called Varicella-Zoster Immune Globulin) is given immediately after exposure (and it must be given not later than 10 days after exposure), the risk of both mother and child coming down with chicken pox can be greatly reduced. While this may not entirely stop the occurrence of varicella or eliminate the risk of Congenital Varicella Syndrome, it can however, reduce the risk to both mother and baby. The use of Varicella-Zoster Immune Globulin should always be considered AS SOON AS exposure to the varicella virus is recognized.
All women who are either about to become pregnant or during early pregnancy should be tested for varicella antibodies and if negative and exposed to varicella should immediately be given Varicella Immune Globulin.
Any woman who comes down with varicella within one week of delivery to one month afterwards should also be given Varicella Immune Globulin.
Important: If you or your child have chicken pox do not just go to your doctor's office without first calling and talking to the doctor. You could expose a pregnant woman or other children waiting to be seen and this could be disastrous. Since you can easily make a diagnosis of Chicken Pox by the rash and symptoms, a trip to the doctors office can be dangerous to others and provide no advantage to you or your child. Please understand and respect this as you would want other s to be considerate of you and your family.
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