Definitive Serological Diagnosis of Ocular Toxoplasmosis

Abstract

The role of<i>Toxoplasma</i>in causing uveitis, especially retinochoroiditis, is now well accepted. It was established by statistical analysis of the high frequency of positive toxoplasmin reactions and serologic (dye) tests in patients with ocular lesions,^1-3by the discovery of parasites morphologically identical with<i>Toxoplasma</i>in sections of enucleated eyes,^4,5and by isolation of the organism from ocular tissues.^6-8 The diagnosis of each patient with retinochoroiditis remains difficult, however, as tests based on serum antibody only do not provide definitive answers for the following reasons: Asymptomatic infections are frequent in the normal population; in France the dye test is positive in 85% of adults, and in the United States, between 20% and 60%, depending on location. Retinal lesions, toxoplasmic or otherwise, may appear in a patient who has a low antibody titer. Proven ocular toxoplasmosis may progress for months in the presence of a stable,