Viral Infections in the Fetus and Neonate

Neonates, like older children and adults, are subject to viral infections acquired by horizontal routes, such as those due to influenza, rotavirus, and enteroviruses. They also are at risk for acquisition of viruses through routes that are unique to the perinatal setting where mother-to-child transmission (MTCT) occurs transplacentally, during birth, or from breast milk. The ability of certain viruses to establish chronic infection in the mother with persistence of infectious virus in blood, mucosa, or milk (herpesviruses, human immunodeficiency virus (HIV), human T-lymphotropic virus 1 (HTLV-1), hepatitis B and C) accounts for the key role vertical transmission plays in their epidemiology and clinical significance. Whether viruses that produce acute, selflimited infections in the mother, such as rubella, varicella-zoster virus (VZV), enteroviruses, and parvovirus B19, are transmitted to the fetus or newborn and produce disease depends on the timing of maternal infection in relation to gestation and parturition. Thus the clinical settings in which fetal and neonatal viral infections must be considered include pregnancy, the newborn nursery, and the evaluation of an ill newborn. This chapter provides an overview of the viral infections that occur in these settings. Detailed discussions of epidemiology, diagnosis, treatment, and prevention are presented in the chapters focused on specific viruses. PATHOGENESIS