An enzyme-linked immunosorbent assay for diagnosis of Fasciola hepatica infection in cattle.

An enzyme-linked immunosorbent assay (ELISA) was investigated for the diagnosis of Fasciola hepatica infection in cattle. Studies included examination of 4 antigen preparations: freshly collected fluke antigen (FFA), dead fluke antigen (DFA), lyophilized fluke antigen (LFA), and partially purified antigen (PPA) for activity and use of an ELISA with FFA and LFA for diagnosis of experimentally and naturally occurring fascioliasis in cattle. The ELISA, using FFA, detected F hepatica antibody in calves as early as 4 weeks after exposure to this parasite. The DFA exhibited slightly less activity, and LFA did not have diagnostic value until 9 to 10 weeks after exposure. The PPA produced high background readings with noninfected control sera and was not considered sufficiently specific for further use. The long incubation and short incubation ELISA procedures can be used for diagnostic work. Both were equally sensitive, with optical density readings of known positive sera routinely 2.5 times those of sera from normal controls. The repeatability of these tests was also excellent, and only slight variation in optical density was observed in ELISA was performed on representative known positive and negative sera with similar reagents in replicate tests.