Varicella in Pregnancy: Five Priorities for Clinicians

Editorial Acute varicella (chicken pox) is one of the most highly contagious viral illnesses. The infection occurs commonly in childhood, and approximately 95 % of individuals are immune by the time they reach childbearing age. Varicella occurs in fewer than 1:1,000 pregnancies each year. Although it is a relatively mild illness in children, varicella may cause severe complications in pregnant women and their fetuses. Accordingly, physicians and nurses who provide obstetric care must be aware of the following 5 priorities. First, at the time of the patient's first prenatal appointment, she should be questioned about a history of varicella. If she is certain she had chicken pox, she should be reassured that second infections are extremely unlikely and that she need not fear accidental exposure to a person with varicella. If the patient is uncertain about her history and a family member is unable to verify that infection occurred, a serologic test to determine immune status should be performed. 2 This test is particularly important in women who have frequent occupational exposure to children with viral illnesses, e.g., school teachers, day care workers, and health care workers. The appropriate serologic test for determining immune status is measurement of IgG antibody by an enzyme-linked immunosorbent assay (ELISA) or the fluorescent antibody test for membrane antigen (FAMA). Approximately 80% of patients with uncertain histories will, in fact, have evidence of immunity, and they can be reassured that they are not at risk during the present pregnancy. Susceptible women must be specifically counseled to avoid exposure to other individuals who may have varicella. The second priority is to promptly and correctly evaluate the obstetric patient who has been exposed to an individual with acute varicella and whose serologic status is either unknown or negative. In the former case a serologic test should immediately be performed. Laboratory personnel must be informed of the need for completion of the test within 24-48 h. If the patient is seronegative or if the laboratory test cannot be completed promptly, the patient should be offered vari-cella-zoster immune globulin (VZIG). This preparation contains high titer of antibody to the varicella-zoster virus, and, if it is given within 4 days of exposure, is of benefit in preventing or attenuating subsequent illness. The appropriate dose of VZIG is vial (125 units) per 10 kg body weight, administered intramuscu-larly, up to a maximum of 5 vials (625 units).