Technical Abstract: Complex and dynamic interactions involving domestic animals, wildlife and humans create environments favorable to the emergence of new diseases, or re-emergence of diseases in new host species. Today, reservoirs of Mycobacterium bovis, the causative agent of tuberculosis in animals and a serious zoonosis, exist in a range of countries and wild animal populations, for example, free-ranging populations of white-tailed deer in the US, brushtail possum in New Zealand, badger in the Republic of Ireland and the United Kingdom, and wild boar in Spain. The establishment of these reservoirs is the direct result of factors including spillover from domestic livestock, translocation of wildlife, supplemental feeding of wildlife, and wildlife populations reaching densities beyond normal habitat carrying capacities due to human intervention. As many countries attempt to eradicate M. bovis from domestic livestock, efforts are impeded by spillback from wildlife reservoirs. It will not be possible to eradicate this important zoonosis from livestock unless transmission between wildlife and domestic animals is halted. Such an endeavor will require a collaborative effort between agricultural, wildlife, environmental and political interests.