Epidemiological investigation of swine tuberculosis in Arizona

Swine tuberculosis occurred in thirteen herds of swine in Arizona. Mycobacterium avium serotypes 1, 2, 4, 5 and 8 were isolated from tissues of affected animals. These serotypes are responsible for approximately 85% of the mycobacterial infections found in swine in the United States. Based on tuberculin skin test responses and examinations of tissues collected at slaughter, the source of infection in at least one of these herds, Herd A, was found to be infected sawdust and wood shavings used as bedding. This finding concurs with the reports of others. Tuberculin skin tests performed on slaughter pigs in Herd A showed a 97.1% correlation between the number of pigs responding to tuberculin and the number found to have tuberculous lesions at slaughter. No correlation of skin test response and presence of lesions was possible for individual pigs, but these results imply that the test may have value when used to determine prevalence of the disease in a herd of pigs.