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 trachea. Five other possums were sham inoculated and housed separately. At postmortem examination 55 to 57 days after inoculation, all six infected possums showed extensive macroscopical lesions of tuberculosis in the lungs and bronchial lymph nodes and some also had lesions in the liver, kidney, spleen and hepatic lymph nodes. Mycobacterium bovis was isolated from all of these possums. No evidence of M. bovis infection was detected in the five control animals. In the M. bovis-infected possums, microscopical examination of organs and lymph nodes demonstrated a much wider distribution of lesions than did macroscopical examination. The location of early lesions indicated that the paracortical region of the lymph nodes, the marginal zone and periphery of lymphoid follicles in the spleen, and the cortex of the kidney were predilection 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.