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 and 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% and 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