Investigation of the transmission of Mycobacterium bovis from deer to cattle through indirect contact.
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.


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


METHODS
In the oral exposure experiment, doses of 4.3 x 10(6) CFUs (high dose) or 5 x 10(3) CFUs (low dose) of M. bovis were each administered orally to 4 calves; as positive controls, 2 calves received M. bovis (1.7 x 10(5) 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 10(5) CFUs (phase I) or 7 x 10(5) 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
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.
Palmer
Mitchell V
MV
Bacterial Diseases of Livestock Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, 2300 Dayton Ave, Ames, IA 50010, USA.
Waters
W Ray
WR
Whipple
Diana L
DL
D000821:Animal Feed / Q000382:microbiology; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology* / Q000635:transmission; D003670:Deer / Q000382:microbiology*; D006799:Housing, Animal; D007371:Interferon-gamma / Q000276:immunology; D009163:Mycobacterium bovis; D014374:Tuberculin Test; D014376:Tuberculosis / Q000635:transmission* / Q000662:veterinary*
D007371:Interferon-gamma