Submitted to: Emerging Diseases Veterinary Medicine Agriculture Human Health Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/13/1999
Publication Date: N/A
Technical Abstract: In 1997, tuberculosis (TB) was diagnosed in a captive herd of white-tailed deer in NE Michigan. The herd was composed of approximately 350 deer on 1500 acres, and operated as a private hunting establishment. The decision to depopulate the herd was made by the owner, the Michigan Dept. of Agriculture, and the USDA. During the depopulation effort, postmortem exams swere done on 116 deer. Various tissues, feces, and swabs of the nasal, oral, tracheal, and tonsilar crypt regions were collected for bacteriologic culture from all 116 deer. Tissues were collected for microscopic examination from deer with gross lesions suggestive of TB. Tuberculous lesions were seen in 9 of 116 deer. Mycobacterium bovis was isolated from tissues of 1 deer with no gross lesions of TB. The most common sites to contain gross lesions were the medial retropharyngeal lymph nodes (6 of 9), and the lung (4 of 9). Three of ten tuberculous deer would have been missed dhad the examination been limited to the head and associated cranial lymph nodes. M. bovis was isolated from swabs of the nasal, oral, tracheal, and tonsilar regions of infected deer as well as some deer with no gross lesions. Pelleted feed, corn, hay, and soil were collected for bacteriologic culture from feeding sites on the 1500-acre premise. Water was collected for bacteriologic culture from ponds used as watering sites. Mycobacterium bovis was not isolated from any feed, hay, soil, or water samples. Some surveys of deer for TB involve examination of the head and cranial lymph nodes only. These results suggest that examination of only the head, will underestimate the prevalence of disease in a naturally infected population. These results further suggest that deer with no gross lesions of TB may be capable of transmitting the organism.