Herpes simplex virus infection of the fetus and newborn.

Although infrequent, untreated neonatal herpes results in death in half the cases and neurologic sequelae in three quarters of the survivors. Neonatal infection is usually acquired from maternal genital herpes, which is asymptomatic or unrecognized in 60% to 80% of women. The greatest risk of neonatal infection occurs when the mother has primary genital herpes involving the cervix at delivery, and the infant is premature and delivered with instrumentation (eg, scalp electrodes). More than 80% of neonates with herpes will have typical herpetic lesions of the skin, eye, or mouth, and most of the remainder will have either encephalitis or a sepsis syndrome with pneumonitis and hepatitis and negative bacterial cultures. Because herpes can mimic other neonatal infections, laboratory diagnosis is important, using cultures of the virus from lesions, peripheral blood white cells, or CSF. Treatment with intravenous acyclovir does reduce mortality and neurologic sequelae, but outcome is still guarded in babies with disseminated disease or encephalitis. Prevention focuses on caesarean section in women with active lesions at the time of impending delivery and avoidance of postnatal exposure. Further studies are needed to determine whether maternal screening (eg, HSV-2 type specific antibodies and vaginal cultures in selected women at delivery) will be cost effective in preventing neonatal herpes.