Babesia divergens: an ELISA with soluble parasite antigen for monitoring the epidemiology of bovine babesiosis.

An enzyme linked immunosorbent assay (ELISA) for bovine babesiosis caused by Babesia divergens was developed to analyse the evolution of the serological status of cattle living in an enzootic area. The antigen used was a soluble extract of B. divergens obtained from in vitro culture. Specificity, evaluated with negative sera, was 96.6%. The ELISA was compared to indirect immunofluorescence analysis (IFA) on naturally or experimentally infected animals. It appeared that IFA was positive for at least seven or eight weeks; on the contrary, B. divergens-specific antibodies were only transitorily detected by ELISA. Furthermore, the ELISA was more sensitive than the IFA for the detection of post-infection antibody increases, particularly when infection-pressure was low. These results suggest that IFA and ELISA could be complementary tools in epidemiological surveys; indeed, this ELISA could be the most efficient tool to detect new infections in cohort monitoring.