Evaluation of crude hydatid cyst fluid antigens for the serological diagnosis of hydatidosis in cattle.

Echinococcosis is a zoonotic infection caused by adult or larval (metacestode) stages of cestodes belonging to the genus Echinococcus. The purpose of this study was to evaluate the antigenic ability of hydatid cyst fluid antigen for the diagnosis of hydatidosis in cattle using enzyme-linked immunosorbent assay (ELISA) and indirect haemagglutination test (IHA). The source of the antigens for the serological tests was fertile crude cyst fluids collected from naturally infected sheep at the Addis Ababa abattoir. A total of 502 sera were collected from 329 uninfected cattle and 173 hydatid-infected cattle which were confirmed by post-mortem examination. Most cysts were sterile and multiple organ infection predominated. Of 173 infected cattle, 166 (96.0%; confidence interval (CI) 91.8-98.4) were positive using ELISA while 7 (4.0%) were negative. Of 329 sera from uninfected cattle, 274 (83.3%; CI 78.8-87.2) were found to be negative and the remaining 55 (16.7%) were positive by ELISA. Of 173 infected cattle, 151 (87.3%; CI 81.4-91.9) were positive and 22 (12.7%) were negative by IHA. Of 329 negative sera tested using IHA, 266 (80.9%; CI 76.2-85.0) were negative and the remaining 63 (19.1%) were positive. The false positive and negative values of ELISA were 4.0 and 16.7%, respectively, and the corresponding values of IHA were 12.7 and 19.1%. The sensitivity and diagnostic efficiency of IHA were 87.2 and 83.6%, respectively. Crude hydatid cyst fluid antigen seems to have reasonable antigenic properties and hence could be employed for epidemiological surveillance of cattle hydatidosis.