elk, or bison herds were in the vicinity and were considered likely sources of sporadic tubercular infections in the wild ungulates.

Recently, tuberculosis caused by M. bovis was diagnosed in an infected captive herd of elk near the northern border of YNP; the disease occurred near free-ranging northern YNP elk (Thoen et al. 1992). On the basis a single tuberculin skin test, the herd had 28 positive reactors; at necropsy, one animal had tuberculous lung lesions from which M. bovis was isolated. A followup disease survey of free-ranging, hunter-killed elk from three areas of YNP revealed no tubercular lung lesions in 289 elk collected between December 1991 and January 1993. Neither M. bovis nor M. paratuberculosis was cultured from specimens. Antibodies to B. abortus were found in serum samples from 0%, 1%, and 1% of elk from the three areas sampled (Rhyan et al. 1997).

If tuberculosis is suspect in bison or elk, the medial and lateral retropharyngeal, mediastinal, and tracheobronchial lymph nodes should be collected and examined bacteriologically and histologically. M. avium can cause tuberculosis in deer but is most often isolated from deer that have no lesions of tuberculosis (Rhyan et al. 1997).

Paratuberculosis

Paratuberculosis (Johne's disease), a chronic intestinal infection of cattle and other ruminants, is a progressive granulomatous enteritis that is seen clinically as severe diarrhea and wasting. Paratuberculosis has been reported in free-ranging ungulates, including bighorn sheep (Ovis canadensis), mountain goat (Oreamnos americanus), tule elk (Cervus elaphus nannodes), axis deer (Axis axis), and fallow deer (Dama dama). Paratuberculosis has been reported in red deer and has been reproduced experimentally in elk, mule deer, and white-tailed deer (Williams et al. 1983). The absence of clinical paratuberculosis and the negative culture results for M. paratuberculosis are consistent with the lack of reports on paratuberculosis in elk in national parks other than YNP (Rhyan et al. 1997). The risk of transmission of paratuberculosis in bison and elk appears to be low, although it does occur.

Leptospirosis

Leptospirosis affects the liver and kidney. Bacteria replicate in the renal



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement