Evaluation of enzyme linked immunosorbent assay, utilizing native antigen B for serodiagnosis of human hydatidosis

Abstract

Background: Hydatidosis is one of the cosmopolitan parasitic zoonoses caused by the larval stage of Echinococcus granulosus. Diagnosis of hydatidosis is still an unresolved problem. Serological tests using crude antigens for diagnosis of E. granulosus are sensitive, however their specificity are not satisfactory. Therefore, WHO recommended specific serological methods using specific antigens, specially native AgB for proper diagnosis.

Objectives: This study was designed to evaluate the ELISA and counter current immunoelectrophresis (CCIEP) method using native antigen B (Ag B) for serodiagnosis of human hydatidosis in Fars Province, Iran, an endemic area for this parasitic disease.

Methods: Native AgB was purified from sheep hydatid fluid. Serum samples obtained from 40 pathologically confirmed cases of hydatidosis along with samples from patients with fascioliasis, toxocariasis, taeniasis and cancer patients and sera from healthy individuals were tested by ELISA using native antigen B or tested by countercurrent immunoelectrophresis (CCIEP) using crude sheep hydatid cyst fluid.

Results: Sensitivity of the ELISA system was determined to be 92.5% and the specificity was found to be 97.3%. Positive and negative predictive values of the system were 92.5% and 97.3%, respectively. For countercurrent immunoelectrophresis the sensitivity of the assay was 97.5% and its specificity was 58.18%. This ELISA system is much more specific in detecting anti hydatid cyst antibody than CCIEP, while CCIEP is more sensitive in detecting anti hydatid cyst antibody.

Conclusion: The new ELISA system using native antigen B is a suitable method and preferable to CCIEP for immunodiagnosis of human hydatidosis.