TUBERCULOSIS IN THE BRUSHTAIL POSSUM (TRICHOSURUS-VULPECULA) AFTER INTRATRACHEAL INOCULATION WITH A LOW-DOSE OF MYCOBACTERIUM-BOVIS

Six possums were each inoculated with approximately 125 colony-forming units of Mycobacterium bovis via a cannula inserted per os into the t rachea. Five other possums were sham inoculated and housed separately. At postmortem examination 55 to 57 days after inoculation, all six in fected possums showed extensive macroscopical lesions of tuberculosis in the lungs and bronchial lymph nodes and some also had lesions in th e liver, kidney, spleen and hepatic lymph nodes. Mycobacterium bovis w as isolated from all of these possums. No evidence of M. bovis infecti on was detected in the five control animals. In the M. bovis-infected possums, microscopical examination of organs and lymph nodes demonstra ted a much wider distribution of lesions than did macroscopical examin ation. The location of early lesions indicated that the paracortical r egion of the lymph nodes, the marginal zone and periphery of lymphoid follicles in the spleen, and the cortex of the kidney were predilectio n sites for lesions resulting from haematogenous spread of infection. This method for reproducing bovine tuberculosis in the possum was more suitable for experimental studies than previously published methods.