Clinical manifestations
Patients with varicella usually have prodromal symptoms and signs that include malaise, fatigue, arthralgias, myalgias, and a low-grade fever. Varicella’s pathognomonic manifestation is a pruritic, macular rash that starts on the face and trunk and then spreads centripetally to the extremities. The lesions typically appear in “crops” and evolve through several distinct phases: macule, papule, vesicle, pustule, ulcer, and crust.5
In children, varicella is manifest almost entirely by mucocutaneous lesions. In adults, however, 2 serious and potentially life-threatening complications can occur. Approximately 1% of infected adults develop encephalitis and about 20% develop viral pneumonia, often accompanied by a severe superimposed bacterial pneumonia.5
When maternal infection develops in the first half of pregnancy, approximately 2% of fetuses will have evidence of congenital infection, usually manifested by circular, constricting scars on the extremities. These lesions typically occur in a dermatomal distribution. Spontaneous abortion and fetal death in utero also have been reported, but fortunately they are quite rare. When maternal infection occurs beyond 20 weeks of gestation, fetal injury is very uncommon.7
Interestingly, when maternal infection occurs at the time of delivery or shortly thereafter (from 5 days before until 2 days after delivery), neonatal varicella may develop. This infection may take 3 forms: disseminated mucocutaneous lesions, a deep-seated visceral infection, or severe pneumonia. In the era before the ready availability of antiviral agents, the case fatality rate from neonatal varicella was approximately 30%.5
Diagnosis is clinical
The diagnosis of varicella usually is established on the basis of clinical examination. It can be confirmed by identification of anti–varicella-zoster IgM.
Management includes assessing immunity
If a patient is seen for a preconception appointment, ask her whether she has ever had varicella or been vaccinated for this disease. If she is uncertain, a varicella-zoster immunoglobulin G (IgG) titer should be ordered. If the IgG titer is negative, denoting susceptibility to infection, the patient should be vaccinated before she tries to conceive (see below).8
If a patient has not had a preconception appointment and now presents for her first prenatal appointment, she should be asked about immunity to varicella. If she is uncertain, a varicella-zoster IgG assay should be obtained. Approximately 75% of patients who are uncertain about immunity will, in fact, be immune. Those who are not immune should be counseled to avoid exposure to individuals who may have varicella, and they should be targeted for vaccination immediately postpartum.5,9
If a susceptible pregnant patient has been exposed to an individual with varicella, she should receive 1 of 2 regimens within 72 to 96 hours to minimize the risk of maternal infection.5,9,10 One option is intramuscular varicella-zoster immune globulin (VariZIG), 125 U/10 kg body weight, with a maximum dose of 625 U (5 vials). The distributor of this agent is FFF Enterprises in Temucula, California (telephone: 800-843-7477). A company representative will assess the patient’s eligibility and deliver the drug within 24 hours if the patient is considered eligible. An alternative prophylactic regimen is oral acyclovir, 800 mg 5 times daily for 7 days, or oral valacyclovir, 1,000 mg 3 times daily for 7 days.
If, despite prophylaxis, the pregnant woman becomes infected, she should immediately be treated with 1 of the oral antiviral regimens described above. If she has evidence of encephalitis, pneumonia, or severe disseminated mucocutaneous infection, or if she is immunosuppressed, she should be hospitalized and treated with intravenous acyclovir, 10 mg/kg infused over 1 hour every 8 hours for 10 days.
Ultrasonography is the most valuable test to identify fetal infection. Key findings that suggest congenital varicella are fetal growth restriction, microcephaly, ventriculomegaly, echogenic foci in the liver, and limb abnormalities. There is no proven therapy for congenital varicella.
When a patient has varicella at the time of delivery, she should be isolated from her infant until all lesions have crusted over. In addition, the neonate should be treated with either VariZIG or an antiviral agent.5,9
Prevention with varicella vaccine
The varicella vaccine (Varivax) is a live-virus vaccine that is highly immunogenic. The vaccine is now part of the routine childhood immunization sequence. Children ages 1 to 12 years require only a single dose of the vaccine. Individuals older than 12 years of age require 2 doses, administered 4 to 6 weeks apart. The vaccine should not be administered during pregnancy. It also should not be administered to individuals who are severely immunocompromised, are receiving high-dose systemic steroids, have untreated tuberculosis, or have an allergy to neomycin, which is a component of the vaccine. The vaccine does not pose a risk to the breastfeeding infant.11
CASE #2 Hospitalization is recommended for this patient
The patient in this case developed acute varicella pneumonia as a result of her exposure to the neighbor’s child. The diagnosis can be confirmed by demonstrating a positive varicella-zoster IgM and by obtaining a chest x-ray that identifies the diffuse patchy infiltrates characteristic of viral pneumonia. Because this is such a potentially serious illness, the patient should be hospitalized and treated with intravenous acyclovir or valacyclovir. Antibiotics such as ceftriaxone and azithromycin may be indicated to treat superimposed bacterial pneumonia. Given the later gestational age, the fetus is at low risk for serious injury. ●