Attempt to improve the diagnostic efficacy of enzyme-linked immunosorbent technique for the serodiagnosis of cystic echinococcosis

ABSTRACT

ELISA with crude hydatid fluid antigen [CHF] is widely used in the immunodiagnosis of cystic echinococcosis, but cross-reactivity with other helminths, overestimating the true prevalence, represents a great limitation. The present study was carried out to comparatively assess the diagnostic performance of three different ELISA techniques; cystatin capture ELISA, sodium metaperiodate treated antigen ELISA [SMP-ELISA] and conventional ELISA, using CHF antigen to detect lgG antibodies in the serum, aiming to increase the diagnostic efficacy of ELISA technique in detection of hydatid disease. The individuals under study were categorized into 3 groups. Hydatidosis group included 30 hydatidosis patients confirmed by IHAT and abdominal ultrasonograpy, computerized tomography or surgical removal with aspiration and cytological examination. Other parasitic diseases group included 10 sera from patients with; amoebiasis [2], fascioliasis [2], toxoplasmosis [3] and schistosomiasis [3]. Control group included 10 healthy individuals. Sera of all groups under study were examined for the detection of E. granulosus IgG by three different EL1SA techniques; cystatin capture ELISA, SMP-ELISA and conventional ELISA. The diagnostic performance of the three tests was statistically compared. The best diagnostic results were obtained with cystatin capture ELISA. with 96.7% sensitivity. 100% specificity, high positive predictive value [PPV] [100%] and negative predictive value [NPV] [95.2%], 98% diagnostic accuracy [DA], and AUC [0.999] with Cl [95%] [0.99-1.0], followed by SMPELISA, with 90% sensitivity, 95% specificity, PPV [96.4%], NPV [86.4%], DA [92%] and AUC [0.995] with CI [95%] [0.97-0.99], then, the conventional ELISA, with 90% sensitivity, 75% specificity. PPV [84.4%], NPV [83.3%], DA [86%], and AUC [0.962] with Cl [95%] [0.88-0.98]. Both cystatin capture ELISA and SMP-ELISA gave equivalent results for the immunodiagnosis of cystic echinococcosis with AUC1-AUC2 < 0.05. Cystatin capture ELISA and SMP-ELISA are valuable tests for serodiagnosis of human cystic echinococcosis as they improved the diagnostic performance of conventional ELISA