EVALUATION OF A POTASSIUM-CHLORIDE EXTRACT OF BRUCELLA-ABORTUS IN AN ELISA FOR DETECTING BRUCELLA ANTIBODIES IN BULK TANK MILK SAMPLES FROMCOWS

An enzyme-linked immunosorbent assay (ELISA) was developed using as an tigen a potassium chloride extract of Brucella abortus strain 1119-3 f or detecting Brucella antibodies in bulk tank samples of cow's milk. T hree-hundred-thirty-four Milk Ring Test (MRT) suspicions milk samples originating from cattle herds in 13 states and 106 BRT negative milk s amples were analyzed. Fifty-four of 334 MRT suspicious milk samples we re positive on ELISA; bacteriologic examinations revealed B. abortus f ield strain was isolated from cows in 15 herds, B. abortus strain 19 w as isolated from cows in 16 herds and serologic suspects were reported in 6 of the other 23 herds. Two-hundred-fifty-eight (85.6%) of the 30 1 MRT suspicious samples were negative on ELISA; field investigations and/or serologic tests on cattle failed to disclose Brucella infection in these herds. Suspicious ELISA reactions were detected in 22 MRT su spicious bulk tank milk samples; serologic suspects were reported in 8 of the 22 herds. No false positive ELISA reactions were detected in t he 106 MRT negative bulk tank milk samples collected from dairy herds in 7 states.