Comparison of three immunological tests for seroepidemiological purposes in human echinococcosis

Abstract

The comparative sensitivity and specificity of 3 immunodiagnostic tests for hydatid [Echinococcus granulosus] disease, the latex agglutination (LA) test, the indirect hemagglutination (IHA) test and the counterimmunoelectrophoresis (CIEP) test, were studied. The results of the IHA test were evaluated using 3 positivity criteria. Antigen from the same source (hydatid cyst fluid pool of ovine origin) was utilized for the 3 tests. A total of 123 sera were studied; 30 preoperative sera from patients with other parasitic and infectious diseases, 30 sera from patients with non-parasitic diseases and 30 sera from normal blood donors. The results of the 3 tests were correlated to the immunoelectrophoresis (IEP) test based on the presence of arc 5. The same sensitivity (86.7%) and specificity (99%) was obtained in LA, CIEP and IHA tests when the minimum cross-reactivity titer criterion was employed for the latter. Non-specificity was relatively high (13%) in the IHA test when only serological reactivity was considered. The sensitivity of the IHA test decreased (83.3%) using the diagnostic titer criterion and non-specific reactions were eliminated. All 3 tests correlated well with the IEP test.