How is toxoplasma retinochoroiditis in HIV infection diagnosed?

Updated: Jun 12, 2019
  • Author: Robert A Copeland, Jr, MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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In the workup, consider syphilis, tuberculosis, and toxocariasis as differential diagnoses. Perform a detailed history and ophthalmologic examination. Serologic detection of antibodies to T gondii is important. Current available testing assays include the indirect hemagglutination assay (IHA) and the immunofluorescent antibody (IFA) test. This test measures both the IgG and IgM antibodies to T gondii. Request that the laboratory perform a 1:1 dilution, as only a positive result is required.

Some less commonly used tests include the Sabin-Feldman dye and the enzyme-linked immunosorbent assay (ELISA) tests. PCR and cytologic demonstration of the organism in vitreous samples could be useful in some cases. Diagnosis of ocular toxoplasmosis requires the demonstration of a characteristic retinochoroiditic lesion and a positive serology at any titer. Fluorescein angiogram may be helpful when a choroidal neovascular membrane is suspected.

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