ABSTRACT
ELISA has become the mainstay for clinical serologic evaluation of toxoplasmosis. One of the major obstacles encountered in the evaluation of ELISA is the false-positive results due to immunological cross-reactions with other parasitic diseases that exhibit some lack of specificity. Evaluation of the diagnostic efficacy of two ELISA techniques: Cystatin capture ELISA and sodium metaperiodate treated antigen-ELISA [SMP-ELISA] compared to conventional ELISA, to detect IgG antibodies for crude T. gondii antigen in sera of toxoplasmosis patients. The study was carried out on 50 individuals categorized into three groups. Toxoplasmosis group included 30 patients confirmed by Sabin-Feldman dye test. Other parasitic diseases group included 10 sera from patients with amoebiasis [2], fascioliasis [2], hydatidosis [3] and schistosomiasis [3]. Control group included 10 healthy individuals. All sera under study were examined for the detection of T gondii IgG by three different ELISA techniques: Cystatin capture ELISA, SMP-ELISA amid conventional ELISA. The diagnostic performance of the three tests was statistically compared. Cystatin capture ELISA gave the best diagnostic results with 96.6% sensitivity, 95% specificity, 96.6% Positive Predictive Value [PPV], 95% Negative Predictive Value [NPV] and 96% diagnostic accuracy. In spite of the lower sensitivity and NPV of SMP-ELISA [86.6% and 82.6%, respectively] than the conventional ELISA, it had higher specificity [95%] and PPV [96.3%]. Cystatin capture ELISA improved the diagnostic performance of conventional ELISA in diagnosis of human toxoplasmosis