Investigation of the Transmission of Mycobacterium bovis from Deer to Cattle Through Indirect Contact

Authors

Mitchell V. Palmer, Bacterial Diseases of Livestock Research Unit, National Animal Disease Center, Agricultural Research Service, USDAFollow
W. Ray Waters, Bacterial Diseases of Livestock Research Unit, National Animal Disease Center, Agricultural Research Service, USDA
Diana L. Whipple, Bacterial Diseases of Livestock Research Unit, National Animal Disease Center, Agricultural Research Service, USDA

Date of this Version

11-2004

Comments

Published in AJVR, Vol 65, No. 11, November 2004.

Abstract

Objective—To investigate the infection of calves with Mycobacterium bovis through oral exposure and transmission of M bovis from experimentally infected white-tailed deer to uninfected cattle through indirect contact.

Animals—24 11-month-old, white-tailed deer and 28 6-month-old, crossbred calves.

Procedure—In the oral exposure experiment, doses of 4.3 X 10⁶ CFUs (high dose) or 5 X 10³ CFUs (low dose) of M bovis were each administered orally to 4 calves; as positive controls, 2 calves received M bovis (1.7 X 10⁵ CFUs) via tonsillar instillation. Calves were euthanatized and examined 133 days after exposure. Deer-to-cattle transmission was assessed in 2 phases (involving 9 uninfected calves and 12 deer each); deer were inoculated with 4 X 10⁵ CFUs (phase I) or 7 X 10⁵ CFUs (phase II) of M Bovis. Calves and deer exchanged pens (phase I; 90 days’ duration) or calves received uneaten feed from deer pens (phase II; 140 days’ duration) daily. At completion, animals were euthanatized and tissues were collected for bacteriologic culture and histologic examination.

Results—In the low- and high-dose groups, 3 of 4 calves and 1 of 4 calves developed tuberculosis, respectively. In phases I and II, 9 of 9 calves and 4 of 9 calves developed tuberculosis, respectively.

Conclusions and Clinical Relevance—Results indicated that experimentally infected deer can transmit M bovis to cattle through sharing of feed. In areas where tuberculosis is endemic in free-ranging white-tailed deer, management practices to prevent access of wildlife to feed intended for livestock should be implemented.