Standardization of a dot immunoperoxidase assay for field diagnosis of Fasciola hepatica infected cattle.

A dot immunoperoxidase assay was developed for the detection of bovine specific antibodies to Fasciola hepatica. The standardization of the assay was done with 298 bovine sera, from seven different groups, previously studied by the reference enzyme-linked immunosorbent assay (ELISA). F. hepatica surface antigens purified by negative affinity against epitopes shared with Paramphistomum spp. and Echinococcus granulosus were used. Starting with sensitized and blocked nitrocellulose strips, the dot immunoperoxidase (DI) assay requires 2 h 15 min at room temperature. The development of a distinct brown dot indicated a positive reaction. The DI test showed a sensitivity of 82%, a specificity of 90%, with a 95% confidence level (CL), good repeatability (kappa 0.741, CL 95%), as well as a significant association with the reference ELISA (kappa 0.618, CL 95%). The DI assay is fast, simple and has a low cost - all convenient characteristics for a screening test to be used in the field.