An evaluation of colostral immunity and the acquired immune response to bovine babesiosis using the complement fixation and the indirect fluorescent antibody tests

Abstract

The complement fixation (CF) and indirect fluorescent antibody (IFA) tests for Babesia biqemina and Babesia argentina were applied to serums collected from 3 experiments. Experiment 1 involved 6 calves infected once with Babesia argentina and 6 calves infected once with Babesia biqemina. In the Babesia arqentina infected calves, the CF and IFA titers were positive at the end of one year, and there was only a low level heterologous titer to Babesia biqemina which persisted for 2 to 4 months. In the Babesia biqemina infected calves, homologous CF titers were low and did not persist over 4 months, but heterologous titers to Babesia arqentina were higher and persisted for over 7 months. Homologous IFA reactions were of high titer to Babesia biqemina and persisted the entire year; heterologous reactions were of low titer and persisted for only 3 months. In experiment 2, six calves born in an endemic zone of Colombia were continually exposed to natural tick-transmitted infections of Babesia arqentina and Babesia biqemina for one year, but they did not develop clinical babesiosis. Serologic titers were positive for both organisms during the first week of life, and protection from the clinical effects of Babesia infections was considered due to protective antibodies in the colostrum. Repeated natural exposure caused fluctuating positive titers during the first year of life. In experiment 3, serums were collected from 5 noninfected calves before ingestion of colostrum from cows with antibody titers to babesiosis, and weekly for 6 months thereafter..