Evaluation of the cold complement fixation test for diagnosis of ovine brucellosis.

A cold complement fixation test for ovine brucellosis in which fixation of complement occurs for 16 h at 4 degrees C was compared with the conventional warm complement fixation test in which fixation takes place for 40 minutes at 37 degrees C. The cold complement fixation test detected experimentally infected animals up to one week sooner than the warm complement fixation test and the titres were approximately one twofold dilution higher. Similar results were obtained when the 2 tests were compared using 11,922 serum samples collected from 700 ram flocks over a 2-year period. False positive reactions were observed in less than 0.1% of cases.