Detection of IgM antibodies against Babesia bovis in cattle

The diagnosis of acute babesiosis by direct examination of blood smears has some limitations and the indirect serological methods currently in use are designed for detection of IgG, which may not be detectable at an early sta ge of infection. There is a need, therefore, for rapid and reliable procedu res to diagnose acute infections. An ELISA system using a crude antigenic p reparation of Babesia bovis was standardized for the detection of IgM antib odies. Optimal dilutions of the antigen, using positive and negative refere nce sera, were determined by checkerboard titrations. Serum samples of catt le imported from tick-free areas collected before and during an immunizatio n process were used to validate the tests. The specificity was 94% and sens itivity 100%. Specific IgM antibodies against B. bovis first appeared on th e 11th day post-inoculation (p.i.) in animals infested with Boophilus micro plus ticks and on the 19th day p.i. in animals which had been inoculated wi th infected blood. Antibody titers decreased after Day 33; however, all ani mals remained positive until the end of the experiment (124 days). (C) 1999 Elsevier Science B.V. All rights reserved.