Background: The aim of this study was to assess the performance of Antigen B (AgB) isolated from different Echinococcus granulosus intermediate hosts and from different cyst locations for immunodiagnosis of human cystic echinococcosis (CE).Methods: Hydatid cyst fluids were collected from lung and liver cysts of sheep, liver cysts of goats, lung cysts of camels and cattle, and liver cysts of human. AgB was purified from each of these hydatid cysts fluids. Serum samples obtained from 47 pathologically confirmed cases of CE along with 30 sera samples from non-CE patients and 40 sera from healthy individuals were tested by ELISA using AgB prepared from different hosts or cyst locations.Results: The highest sensitivity (97.8%) for diagnosis of CE was seen with AgB prepared from human liver cysts. This maximal sensitivity was followed by AgB isolated from those of sheep liver and lung cysts. The least sensitivity was found with AgB prepared from bovine lung cysts. The highest specificities (97.1%) were observed with AgB isolated from human liver cysts followed by those of sheep and goat liver cysts while the lowest specificity was seen with AgB isolated from bovine lung cysts. In view of the specificities and sensitivities of the different AgB, the best validity was found for AgB prepared from human liver cysts while the least validity was found with AgB prepared from bovine lung cysts. Conclusion: For any AgB-based tests, obtaining of the antigen from one of these sources will significantly increase the diagnostic sensitivity and specificity of the assay
