Exposure and Shedding in Milk of Mycobacterium bovis in Dairy Herds Using One-Step Anigen® Rapid Bovine Tuberculosis Antibodies Test and Ziehl-Neelsen Stain
This study was carried out to detect exposure to Mycobacterium bovis (M. bovis) in four dairy herds consisting of a total of 200 cows, aged between 21/2-10 years. The cows were of various breeds, namely: white Fulani (Bunaji), crosses of white Fulani and sokoto gudali, white Fulani and Friesian, semi-intensively managed and producing milk for yoghourt production in Kaduna and environs. Anigen® Rapid Bovine Tuberculosis Antibody Test (IQRT) specific for M. bovis antibodies in sera of cows were used in this study. The result showed 17.5% (35/200) positive for antibodies to M. bovis. Fresh milk from cows positive to the IQRT and also packed yoghourts made from milk obtained from those positive and negative cows in the sampled dairy herds were collected and subjected to Ziehl-Neelsen Stain (ZNS) in order to detect bacilli in fresh milk and packed yoghourts. The result obtained 17.1% (6/35) of these cows were shedding the bacilli in fresh milk while no bacillus detected in the packed yoghourts. The result showed that IQRT was sensitive in detecting M. bovis before they start shedding in milk while ZNS technique was found to be potentially useful in detecting M. bovis infected lactating cows that are shedding the bacilli in milk. This study has shown that apparently healthy lactating cows may shed viable M. bovis in milk there by posing a serious public health problem where unpasteurized milk is consumed. This calls for the need to ensure that only non-positive milking cows are milked for human consumption and the IQRT is the best of choice to determine that.