The distribution of Mycobacterium bovis in Queensland cattle herds with observations on the laboratory diagnosis of tuberculosis.

Of 1,791 tissues submitted from 1975 to 1978 for histological examination for tuberculosis, 78.5% were classified as tuberculosis, 8.1% as club-forming granulomas, 3.3% as hydatid cysts, 3.4% as other granulomas and 2.4% as squamous cell carcinomas. Cultural examination of 2,682 tissues for mycobacteria yielded Mycobacterium bovis from 42.88%, other mycobacteria from 7.64% and 0.89% Rhodococcus (Corynebacterium) equi. Of 1,478 tissues on which both examinations were performed, culture and histology results were in agreement on 94.1%. M. Bovis was isolated on one or more occasions from 564 herds with the highest herd prevalence being recorded in western areas of the state. Culture of 1,024 tissues from no visible lesion (NVL) reactors yielded 0.59% M. bovis, 15.04% other mycobacteria and 0.19% R. equi. Of 120 isolates of other mycobacteria from tissues of NVL reactors, 39 were Runyon Group III (20 M.avium complex) and 61 Runyon Group IV. Approximately half of the herds from which NVL tissues were collected were confirmed M. bovis infected properties.