Review for disease of the year: differential diagnosis of ocular toxoplasmosis.

The diagnosis of ocular toxoplasmosis is mainly clinical, based in the presence of focal necrotizing retinochoroiditis often associated with a preexistent chorioretinal scar, and variable involvement of the vitreous, retinal blood vessels, optic nerve, and anterior segment of the eye. Recognition of this clinical spectrum of toxoplasmic retinochoroiditis is crucial, but other infectious, noninfectious, and neoplastic entities should also be considered in the differential diagnosis. Investigations such as serological tests, polymerase chain reaction of ocular fluids, and assessment of intraocular antibody synthesis are helpful in uncertain cases. This article provides an overview of the differential diagnosis of ocular toxoplasmosis, focusing on the most important entities to be considered and emphasizing distinctive features of each one of them in the clinical setting. Ocular toxoplasmosis has multiple clinical manifestations, which partially overlap with those of other entities and these should be carefully considered when making the differential diagnosis, particularly in less typical cases.

Necrotizing retinitis induced by Angiostrongylus cantonensis.

PURPOSE: To describe a case of bilateral necrotizing retinitis induced by Angiostrongylus cantonensis. DESIGN: Interventional case report. METHODS: A 52-year-old Asian woman developed eosinophilic meningitis after eating several undercooked snails. One week later, sudden onset of vision loss was noted in both eyes. Widespread yellow retinal exudates were accompanied by bullous retinal detachment in both eyes. RESULTS: Angiostrongylus cantonensis infection was confirmed by positive enzyme-linked immunosorbent assay of the serum and cerebrospinal fluid, and a positive Western blot test of the subretinal fluid. After treatment with mebendazole, levamisole, and corticosteroid, these necrotizing patches regressed gradually. However, the final visual acuity was no light perception. CONCLUSIONS: Angiostrongylus cantonensis infection should be considered as one of the causes of necrotizing retinitis.

Toxoplasmosis transmitted to a newborn from the mother infected 20 years earlier.

PURPOSE: To present a case of congenital toxoplasmosis in a newborn whose mother had a 20-year history of a chorioretinal macular scar and positive serology for toxoplasmosis. DESIGN/METHODS: Case report. SETTING/RESULTS: A 38-year-old woman who had been treated for ocular toxoplasmosis 20 years earlier delivered a newborn who presented with a focal necrotizing retinochoroiditis characteristic of toxoplasmosis, as well as positive immunoglobulin (Ig) G and M serology for toxoplasmosis. The workup was negative for other entities. CONCLUSION: This case suggests that women with old retinal scars due to toxoplasmosis and long-standing IgG antibodies to toxoplasmosis are also at risk of transmitting this disease to the fetus.

Presumed acquired ocular toxoplasmosis in deer hunters.

PURPOSE: To describe acquired ocular toxoplasmosis in deer hunters. METHODS AND RESULTS: The authors describe five young men presenting with flu-like symptoms followed by visual loss due to a unilateral, focal necrotizing retinitis. All five men gave a history of ingesting undercooked or uncooked venison. All five had elevated toxoplasma serology, and all five improved clinically with an antitoxoplasma regimen. CONCLUSION: In previously healthy young men, flu-like symptoms associated with visual loss and retinitis should prompt questioning about hunting and raw game meat ingestion, especially when toxoplasmosis is suspected.

Histopathological features of ocular toxoplasmosis in the fetus and infant.

BACKGROUND: Ocular disease is a frequent manifestation of congenital Toxoplasma gondii infection. There are only limited data available in the literature concerning early stages of this disease in fetuses and infants. The purpose of our study was to characterize histopathological features in the eyes 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 examined by light microscopy. Immunohistochemical analysis to identify inflammatory cells and T gondii antigens was performed. The findings in infected eyes 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 and congestion (15/18 eyes) were characteristic findings. Optic neuritis was present in 5 of 8 fetal eyes with associated optic nerve available for evaluation. 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. Parasites 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 contribute to ocular damage. These findings have important implications for serological screening programs and in utero therapy.

Interpretation of intraocular and serum antibody levels in necrotizing retinitis.

BACKGROUND: Intraocular antibodies have been measured as a diagnostic aid in necrotizing retinitis but interpretation of results may be difficult. METHODS: Vitreous or aqueous and serum immunoglobulin G antibodies to toxoplasmosis, cytomegalovirus, herpes simplex virus I and II, and varicella zoster virus were subjected to enzyme-linked immunosorbent assay in 27 patients with necrotizing retinitis and 15 control patients. A quotient was derived quantitating the amount of excess antibody in the eye compared to serum. Different interpretative rules were analyzed to determine which yielded the highest sensitivity and specificity. RESULTS: The highest intraocular antibody relative to serum among the 4 antibodies correctly predicted the final clinical diagnosis in 21 of 27 patients, for a sensitivity of 78% and a specificity of 90%. Interpretive rules that relied on a high numeric value of the antibody quotient or did not consider the relative ranking of the four antibody quotients were less sensitive and specific because multiple antibodies were detected in most eyes. The technique was safe and rapid. CONCLUSION: Interpretation of antibody titers in intraocular fluids is facilitated by testing several relevant antibodies and comparing the results. The technique may be helpful to diagnose necrotizing retinitis and to ascertain viral cause in acute retinal necrosis.

Aggressive toxoplasma retinitis.

Toxoplasma infection is a common cause of infectious uveitis. It usually produces a characteristic fundal appearance, with evidence of previous inflammation. However, it may occur in an atypical and aggressive form. Steroids administered to salvage vision may then worsen the clinical course. Retinal biopsy may be diagnostic in cases where doubt exists. We illustrate these points with two cases.