Occurrence of Mycobacterium bovis infection in cattle in Kaduna metropolis and its environs

The tedious nature of tuberculin tests in Nigeria, warrants the need for an alternative rapid animal-side means of diagnosis. The aim of this study was to provide information on the epidemiology of Mycobacterium bovis infection in cattle. An experiment was conducted to evaluate the occurrence of M. bovis infection in cattle in Kaduna metropolis and it's environ. A total 239 heads of cattle from 8 herds were randomly selected and tuberculin tested, two herds being from each of the four local government areas involved and pooled milk samples from the eight herds were tested for acid fastness. Also, all heads of cattle totaling 2978 slaughtered at the 2 abattoirs during the month of May, 2012 were examined at postmortem and tissues with lesions compatible with lesions of were collected and tested for acid fastness. The results of the experiment showed that only 23 (9.6%) of the animals tested were classified as reactors and these came from only one of the eight herds studied. A clear swelling was seen in each of the positive cases. Out of the eight herds tested, 6 (75%) were settled and the remaining 2 (25%) were semi- settled. Similarly, 6 (75%) of the herds were for mixed production system and 2(25%) were kept solely as dairy herds. Positive tuberculin test was only observed from among one of the six settled herds 1(17%) while cattle in the remaining 5(83%} settled herds all tested negative. All the two semi-settled herds (100%) tested negative. The tuberculin reaction among different production systems showed that only 1 (50%) of the dairy herds tested positive and all the 6 (100%) mixed herds tested negative. Atuberculin positive reaction of 19 (7.9%) was observed among the females and 4 (1.67%) among the males. The chi-square test of significance between the tuberculin reaction and sex of the animals showed no significant effect (P > 0.05). Hence, it can be concluded that, Mycobacterium bovis was neither cultured nor isolated and therefore, could not be confirmed responsible for the observed reactions. However, its involvement is strongly suggested by both its higher values compared to those for Mycobacterium avium in the single intradermal comparative tuberculin test and the observed in the stained smears of both the milk samples collected and the bovine tissues from the abattoirs.