Infants with any of these infections share certain common features, such as low birth weight, prematurity, congenital heart disease, purpura, jaundice, anemia, microcephaly or hydrocephaly, cerebral calcifications, chorioretinitis, cataracts, microphthalmia, and pneumonitis; as a corollary, if any combination of these features is manifest, one should suspect one of these infectious agents and take measures to identify it. However, all these clinical manifestations are unlikely to be present in any one infant, and in the cases of rubella and CMV, only a small percentage of infected infants will show major systemic signs or symptoms. Nevertheless, on clinical grounds alone, certain infections can be identified and others excluded. For example, cerebral calcifications are present mainly in toxoplasmosis and CMV encephalopathy, being rare in rubella and absent in herpes simplex virus (HSV) encephalitis; the calcifications are widely disseminated in toxoplasmosis (Fig. 37-16) and have a periventricular distribution in CMV infection. Cardiac lesions are present only with rubella, and deafness occurs only with CMV and rubella. Thus, there are clinical signposts to guide the clinician in selecting the appropriate diagnostic tests. And importantly, in considering neonatal infections, one must also search for other, less-common infectious types (see Chaps. 31 and 32).
Added difficulty in the diagnosis of embryonal and fetal infections arises when the mother has been entirely asymptomatic. Isolation of the organism from fetal and neonatal tissues is possible, but usually they are inaccessible, and it may be impossible to demonstrate antibodies or other immune responses because of the early stage of the infection or limitations of the infant’s immune response.
Gregg, in 1941, first reported the association of maternal rubella and congenital cataracts in the neonate. His observations were quickly verified, and soon it became widely known that cataracts, deafness, congenital heart disease, and developmental delay constituted a kind of tetrad diagnostic of this disease. That a virus could affect so many tissues, causing in essence a noninflammatory developmental disorder of multiple organs, was a novel concept, and it raised the interesting prospect that other viruses might have similar effects. Surprisingly, however, only CMV and possibly HSV have been incriminated in embryonal-developmental neuropathology. A large number of other viruses (e.g., influenza, Epstein-Barr, hepatitis) have been implicated in human teratogenesis, but in none is the relationship beyond doubt.
It is now well established that most instances of congenital rubella infection occur in the first 10 weeks of gestation and that the earlier the infection occurs, the greater the risk to the fetus. However, there may be some risk beyond the first trimester, up to the twenty-fourth week, according to Hardy.
Following the experience of the massive rubella epidemics of 1964 and 1965, the congenital rubella syndrome has been expanded to include low birth weight; sensorineural deafness, sometimes unilateral (the most common complication); microphthalmia; pigmentary degeneration of the retina (salt-and-pepper chorioretinitis); glaucoma, cloudy corneas, and cataracts of special type (the latter two abnormalities usually cause visual impairment); hepatosplenomegaly, jaundice, and thrombocytopenic purpura; and patent ductus arteriosus or interventricular septal defect. There may be one, a few, or many of these abnormalities, in various combinations. The developmental delay is severe and may be accompanied by seizures and motor defects such as hemiplegia or spastic diplegia and rarely by seizures. Psychiatric symptoms, some resembling autism, are said to occur.