Maternally transmitted congenital infections cause ocular damage through one or more of the following means: direct action of the infecting agent, which damages tissue; a teratogenic effect, which causes malformation; or delayed reactivation of the agent after birth, which damages developed tissue by direct action or inflammation.
Most perinatal disorders have a broad spectrum of clinical presentation, ranging from silent disease to life-threatening tissue and organ damage. Common, classic types of congenital infections are represented in the mnemonic TORCH: toxoplasmosis, rubella, cytomegalovirus, and herpesviruses.
Systemic infection in humans by the obligate intracellular parasite Toxoplasma gondii is common and usually goes undiagnosed. Felines are the definitive host. Signs and symptoms may include fever, lymphadenopathy, and sore throat. The percentage of antibody titer–positive persons in the United States increases with age (younger than 5 years, 5%; older than 80 years, 60%).
The incidence of congenital toxoplasmosis ranges from 1 to 10 per 10,000 live births. Toxoplasmosis can be acquired congenitally via transplacental transmission from an infected mother to the fetus. Congenital infection can result in retinitis, hepatosplenomegaly, intracranial calcifications, microcephaly, and developmental delay.
Ocular manifestations besides retinitis include choroiditis, iritis, and anterior uveitis (Fig 28-25). The area of active retinal inflammation is usually thickened and cream colored with an overlying vitritis, frequently in the macula. This area may be at the edge of an old, flat, atrophic scar (a so-called satellite lesion). Previously, apparently acquired Toxoplasma retinitis was thought to represent reactivation of a congenital infection; however, recent evidence suggests that most of these patients are infected postnatally. Diagnosis is primarily clinical.
Figure 28-25 Toxoplasmosis chorioretinitis, right eye.
Ocular toxoplasmosis does not require treatment unless it threatens vision. Systemic treatment involves the use of one or more antimicrobial drugs with or without oral corticosteroids. Commonly used antimicrobial agents are pyrimethamine and sulfadiazine. Corticosteroids should typically be used with antimicrobial coverage. Intravitreal injection of clindamycin and dexamethasone has been reported as a possible alternative treatment.
Further details regarding diagnosis and management can be found in BCSC Section 9, Uveitis and Ocular Inflammation.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.