Submitted to: International Congress on Anthrax, Brucellosis, CBPP, Mycobacterial Disease
Publication Type: Proceedings
Publication Acceptance Date: May 1, 1998
Publication Date: N/A
Technical Abstract: Tuberculosis caused by Mycobacterium bovis has recently been detected in free-ranging white-tailed deer in Michigan, USA. Presence of a wild reservoir of tuberculosis is a serious threat to the bovine TB eradication effort. Eradication of TB in white-tailed deer will require a better understanding of disease pathogenesis, diagnosis, and transmission. We developed a model of natural infection using intratonsilar inoculation of white-tailed deer with M. bovis. Routes of transmission were evaluated by culture of nasal, oral, tonsilar, and rectal swabs. M. bovis was isolated from tonsilar swabs from 8 of 9 deer at various times 14 to 87 days after inoculation. M. bovis was isolated from saliva 63 and 80 days after inoculation from 1 of 9 deer. Similarly, M. bovis was isolated from nasal secretions 63 days after inoculation from 1 of 9 deer. Deer were euthanatized and examined 87 days after inoculation. Tuberculous lesions were seen most commonly in medial retropharyngeal lymph nodes and lung, bu also involved distant lymphoid and nonlymphoid organs. Comparative cervical skin testing (CCT) positively identified all M. bovis-inoculated animals, however, one saline control was also identified as positive for M. bovis exposure by the CCT. A mycobacterial species other than M. bovis was isolated from this control deer. Intratonsilar inoculation with M. bovis results in lesions similar to those seen in natural infection. Shedding of M. bovis in saliva and nasal secretions represents a likely route of transmission of disease from deer to deer, as well as to other animals, including humans.