Shared feed as a means of deer-to-deer transmission of Mycobacterium bovis

To determine the ability of experimentally inoculated white-tailed deer (Odocoileus virginianus) to transmit Mycobacterium bovis to naïve deer through the sharing of feed, four deer were intratonsillarly inoculated with 4 x 10(5) colony-forming units of M. bovis. On a daily basis, feed not consumed by inoculated deer after approximately 8 hr was offered to four naïve deer maintained in a separate pen, where direct contact, aerosol transmission, or transmission through personnel were prevented. After 150 days, naïve deer were euthanized and examined. All naïve deer had lesions consistent with tuberculosis and M. bovis was isolated from various tissues. The most commonly affected tissues were lung, tracheobronchial lymph nodes, and mediastinal lymph nodes. This study demonstrates the potential for indirect transmission of M. bovis through the sharing of feed. Intentional or unintentional feeding of deer by wildlife or agricultural interests in regions where M. bovis infection is endemic should be avoided because both direct and indirect transmission through sharing of feed are enhanced.