Latex agglutination and indirect immunofluorescence tests in the diagnosis of Toxoplasma gondii in Saudi Arabia.

Commercial latex agglutination (LA) was assessed for Toxoplasma antibody screening. The sensitivity and specificity were compared with the reference standard indirect immunofluorescence (IFA). A total of 186 sera were collected from May 2008-October 2008 for Toxoplasma antibody by LA & IFA. Antibody to T. gondii 51/186 (27.4%) were LA-positive and 42/186 (22.6%) were IFA-positive. The sensitivity, specificity and positive predictive value of LA were 100%, 93.7% & 82.3% respectively. The nine LA-false positive sera were examined for rheumatoid factor and antinuclear antibodies, but were negative and none exhibited nonspecific polar staining as a cause for the false positivity.