Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Abstract Only
Publication Acceptance Date: 10/7/1999
Publication Date: N/A
Technical Abstract: In 1997 tuberculosis 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 was operated as a private hunting establishment. The decision to depopulate the herd was made by the owner, the MI Dept. of Ag., and the USDA. During the depopulation effort, postmortem examinations were done on 116 deer. Various tissues, feces, and swabs of the nasal, oral, 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 tuberculosis. Tuberculous lesions were seen in 9 of 116 deer. Mycobacterium bovis was isolated from 1 deer that had 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 had the examination been limited to the head and associated cranial lymph nodes. Swabs of the tonsilar crypt from 1 of 116 deer contained M. bovis. All other swabs and fecal samples were negative for the presence of M. bovis. 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. M. bovis was not isolated from any feed, hay, soil, or water samples. Some surveys for TB in white-tailed deer involve examination of the head and cranial lymph nodes only. These results suggest that examination of the head alone, will underestimate the prevalence of disease in a naturally infected population. These results further suggest that environmental survival of M. bovis in feed, soil, or water may not play an important role in the transmission of the disease.