Since tuberculosis was first reported in possums in New Zealand in 1970 field surveys and experimental work have contributed significantly to our understanding of the epidemiology and pathology of the disease.

Infected possum communities have been discovered in 23 general localities throughout New Zealand. There is compelling evidence linking tuberculosis in possums to high and persistent reactor rates in cattle in the same environment.

The possum is very susceptible to the effect of infection with Mycobacterium bovis and will develop a progressive and fatal disease with wide dissemination of lesions. The lesions are characterised by a limited cellular response, extensive tissue necrosis and a high rate of multiplication of the bacilli.

It is highly probable that tuberculosis can maintain itself in a population of possums and serve as a continuing source of re-infection for cattle and as a risk to people handling possum carcases.