Epidemiology of mycobacterial lymphadenitis in an Idaho swine herd

A study of Mycobacterium avium infected swine in an Idaho herd was made to obtain information on morbidity and to evaluate some control measures. Of 867 pigs slaughtered during a 30-day period in May and June, 1974, 100 carcasses were condemned or passed for cooking and 406 carcasses had lesions in one lymph node and were passed without restriction. Mycobacteriologic examinations were made on 33 pigs which were tuberculin tested. Mycobacterium avium was isolated from 21 of 26 tuberculin positive pigs and from 4 to 7 tuberculin negative pigs. Lymphocyte stimulation tests were completed for 12 pigs. Positive results were observed in 11 and M. avium was isolated from 7. Mycobacterium avium serotypes 1,2,4,8, and 9 were identified.