Comparable Study of Immunological, Bacteriological, and Molecular Techniques for Detecting Brucellosis in Milk of Reproductively Problematic Cows

Document Type : Original Article


1 Biotechnology Department Animal Health Research Institute (AHRI), Agriculture Research Center (ARC), Egypt

2 Bacteriology Department Brucella unit, Animal Health Research Institute (AHRI), Agriculture Research Center (ARC), Egypt

3 4) Biotechnology Department, Animal Health Research Institute (AHRI), Agriculture Research Center (ARC), P.O. 12611, Giza, Egypt


Brucellosis, a serious animal infectious disease transmitted to human beings, is a major health risk for dairy consumers, especially in developing-countries resulting in dangerous economic and financial problems. Brucellosis diagnosis is critical in order to detect this infection and find a suitable treatment. Accordingly, this study aims to follow up on the accuracy and sensitivity of different diagnostic techniques used in detecting brucellosis in milk (immunological, bacteriological, and molecular techniques). Milk ring test (MRT) and indirect enzyme-linked immunosorbent assay (i-ELISA) are among the used techniques where positive brucellosis was detected in milk samples with total percentages of 34.91% and 33.96%, respectively. The recorded relative-sensitivity for MRT and i-ELISA were 93.55% and 96.77%, respectively, while their relative-specificities were 89.33% and 92%, respectively. i-ELISA was found to show both higher relative sensitivity and specificity than the MRT technique. The percentage of Brucella species detected in milk samples via bacteriological culture was 25.5% and all of them were reported to be B. melitensis biovar 3. On the other hand, 28.3% of samples were positively detected in both conventional and qPCR samples. The relative-sensitivities were 87.10%, 96.77%, and 96.77% for bacteriological culture, conventional-PCR, and qPCR techniques, respectively. All three techniques reported relative-specificities of 100%. The most predominant species detected in cows’ milk suffering from reproductive disorders is B. melitensis biovar 3. Both PCR techniques showed the highest relative-sensitivity and specificity in addition to being rapid and low-risk techniques making PCR the best diagnostic technique for brucellosis.


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