Congenital infections, historically referred to as TORCH infections, comprise a group of diseases that affect the fetus and newborn. Classically, the acronym TORCH represented toxoplasmosis, other (traditionally syphilis), rubella, cytomegalovirus (CMV), and herpes simplex virus (HSV). The “other” category has expanded to include human immunodeficiency virus (HIV), enterovirus, parvovirus, varicella, and most recently, Zika virus. These congenital infections share many clinical manifestations. Consequently, the differential diagnosis of one congenital infection includes the others (Table 53-1). The prevalence of various congenital infections is variable. Infection due to rubella and toxoplasmosis is rarely seen in the United States, while CMV is common, representing a significant public health concern. Although HIV can be a congenital infection, it is more commonly acquired perinatally.
Viral infections in pregnancy can be associated with poor pregnancy outcomes and birth defects through three mechanisms: (1) infection of the fetus through the placenta; (2) infection of the cells at the maternal–fetal interface, resulting in placental insufficiency; and (3) infection of the cells at the maternal–fetal interface resulting in the production of immune factors that then affect the fetus.1 This chapter discusses the epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, and management strategies for infants affected with congenital infections. HSV is addressed in additional detail in Chapter 54 (on perinatal infections); while HSV may occur as a congenital infection, perinatal acquisition is more common.
DEFINITIONS AND EPIDEMIOLOGY
Cytomegalovirus is the most common cause of congenital viral infections.2 It is a double-stranded, species-specific DNA virus of the herpesvirus family.3 Infection in the immunoincompetent, vulnerable fetus can have devastating effects. Congenital CMV infection is a leading cause of acquired sensorineural hearing loss (SNHL) and neurodevelopmental disturbances resulting from central nervous system (CNS) involvement.3,4
The incidence of primary CMV infection in pregnancies is estimated to range from 0.7% to 4%, with vertical transmission rates as high as 40%.2 CMV IgG seroprevalence, which indicates history of CMV infection, is associated with older age, female sex, foreign birthplace, and low socioeconomic status.5 Testing of specimens from the Third National Health and Nutrition Examination Survey showed seroprevalence of 36% in persons aged 6–11 years and 88.8% in those aged 70–79 years.6 The seroconversion rate in pregnancy in the United States is approximately 2%.6,7 The ...