Using of competitive ELISA in detection of brucella antibodies in cattle sera

Competitive ELISA test was used in this study to identify brucella antibodies in cattle sera in Mosul, and assessing the results that are given by Rose-Bengal test. Results of testing 126 cattle sera revealed that the seroprevalence was 16.7% using C-ELISA and 18.3% using RBT. There were differences in seroprevalence according to sex of animals, females showed higher seroprevalence than males, it was 19.1% and 20.2% in females and 9.4% and 12.5% in males by C-ELISA and RBT respectively. Also there were differences in seroprevalence according to age of animals and pregnancy status of females. Kappa value revealed that there was little agreement between C-ELISA and RBT, (Kappa value was 0.229). RBT was not accurate in giving real seroprevalence, since there were 13 false-negative samples from 21 samples positive with C-ELISA, and there were 15 false-positive samples from 105 samples negative with C-ELISA. Results of tube agglutination test and 2-Mercaptoethanol test indicated a decline of titers from those of previous studies, lower titer of TAT was 1/10 (19.05%) and most of titers were lower than 1/40 (76.2%) in 2-Me test. This study concluded that the brucella antibodies in cattle sera in Mosul was increased from previous years and most of cases were acute.