A Comparative Evaluation of Four Different Immunoassays in the Diagnosis of Cystic Echinococcosis Using a Crude and Purified Hydatid Cyst Fluid Antigen

Purpose Cystic echinococcosis (CE) is one of the most neglected tropical diseases as per WHO which has an immense public health significance. Diagnosis of CE is difficult as specific clinical signs are manifested only after the hydatid cyst attains a considerable size. Immunodiagnosis is a reliable method of diagnosing CE. Methods SDS-PAGE was performed for the hydatid cyst fluid antigens. The antigen purity was tested by Western blotting and four different immunoassays were evaluated using these two antigens in sheep and buffalo in diagnosis of CE. Results SDS-PAGE revealed four bands of 72, 64, 48 and 24 kDa for crude antigen and a single 72 kDa band for purified antigen. Among sheep sera, ELISA was most sensitive (70%) using crude antigen and also while using the purified antigen (80%). In case of buffaloes, ELISA, DID and CIEP were more sensitive (83.3%) using crude antigen, whereas DID and CIEP were more sensitive (83.3%) using purified antigen. Conclusion In sheep, while using the crude antigen ELISA was the most sensitive assay and IHA was the least sensitive assay. While using the purified antigen also, ELISA was the most sensitive and others were absolutely specific except for IHA being less sensitive. In buffaloes, using crude antigen, all the immunoassays CIEP, DID and ELISA were highly sensitive in diagnosing CE infection except IHA, whereas using the purified antigen, both CIEP and DID were more sensitive than ELISA and IHA which were comparatively less sensitive in detecting CE in buffalo sera.