Histopathological features of ocular toxoplasmosis in the fetus and infant

Background: Ocular disease is a frequent manifestation of congenital Toxopl asma gondii infection. There are only limited data available in the literat ure concerning early stages of this disease in fetuses and infants. The pur pose of our study was to characterize histopathological features in the eye s of 10 fetuses and 2 infants with congenital toxoplasmosis. Methods: Fifteen eyes from 10 fetuses, 3 eyes from 2 premature infants, and both eyes from a 2-year-old child with congenital toxoplasmosis were exami ned by light microscopy. Immunohistochemical analysis to identify inflammat ory cells and T gondii antigens was performed. The findings in infected eye s were compared with those of age-matched control eyes. Results: Retinitis(10/18 eyes), retinal necrosis (4/18 eyes), disruption of the retinal pigment epithelium (12/18 eyes), and choroidal inflammation an d congestion (15/18 eyes) were characteristic findings. Optic neuritis was present in 5 of 8 fetal eyes with associated optic nerve available for eval uation. An eye obtained from a 32-week-old fetus showed retinal rosettes at the edge of a scar. T cells predominated in retinal lesions and choroid. P arasites were identified by immunohistochemical analysis in 10 of 18 eyes. Conclusions: Ocular toxoplasmosis causes irreversible damage to the retina in utero. The fetus and infant mount inflammatory responses that may contri bute to ocular damage. These findings have important implications for serol ogical screening programs and in utero therapy.