Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: PREVENTION AND CONTROL STRATEGIES FOR TUBERCULOSIS IN CATTLE AND WILDLIFE RESERVOIRS Title: Persistence of Mycobacterium bovis bacillus Calmette-Guerin (BCG) Danish in White-tailed deer (Odocoileus virginianus) vaccinated with a lipid-formulated oral vaccine

Authors
item Palmer, Mitchell
item Thacker, Tyler
item Waters, Wade
item Robbe-Austerman, S -
item Aldwell, F -

Submitted to: Transboundary and Emerging Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 23, 2012
Publication Date: November 23, 2012
Citation: Palmer, M.V., Thacker, T.C., Waters, W.R., Robbe-Austerman, S., Aldwell, F.E. 2012. Persistence of Mycobacterium bovis bacillus Calmette-Guerin (BCG) Danish in White-tailed deer (Odocoileus virginianus) vaccinated with a lipid-formulated oral vaccine. Transboundary and Emerging Diseases. DOI.org/10.1111/tbed.12032.

Interpretive Summary: The bacterium known as Mycobacterium bovis (M. bovis) is the causative agent of tuberculosis in many animals, including humans. Historically, public health concerns prompted programs to eliminate tuberculosis from cattle in many nations. Many of these efforts successfully decreased the number of M. bovis-infected cattle; nevertheless, some countries encountered significant obstacles, not the least of which, was a wildlife reservoir of M. bovis. In the U.S. wild white-tailed deer represent such a reservoir. Efforts to decrease the deer population have neither eliminated disease nor eliminated transmission to cattle. Consequently, the use of a vaccine is being explored. The vaccine most studied for use is M. bovis BCG, a weakened, but live vaccine, first developed 100 years ago. The most efficient and effective means of vaccinating wild deer will be an oral vaccine. White-tailed deer are a popular game species, and as such, represent a food animal to many hunters. BCG persistence in deer tissues could result in human exposure to BCG. Although not disease causing, BCG exposure could induce false positive skin test results, confounding the use skin testing, a crucial part of public health surveillance for TB. It was found that BCG given in higher doses remained in the deer tissues for up to 1 yr after vaccination. Persistence of BCG was limited to tissues not normally consumed by hunters and was never found in samples of muscle (meat) collected at each time point. Although the risk of exposure to hunters is low, BCG persistence should be considered prior to field use in white-tailed deer.

Technical Abstract: Mycobacterium bovis, the causative agent of tuberculosis in animals has a broad host range, including humans. Historically, public health concerns prompted programs to eradicate tuberculosis from cattle in many nations. Eradication efforts decreased the prevalence of bovine tuberculosis; nevertheless, some countries encountered significant obstacles, not the least of which, was a wildlife reservoir of M. bovis. Efforts to decrease the size of the wildlife population have neither eliminated disease nor eliminated transmission to cattle. Consequently, the use of a wildlife vaccine is being explored. The vaccine most studied is M. bovis BCG, an attenuated live vaccine, first developed 100 years ago. The most efficient and effective means of vaccinating wildlife will be an oral vaccine. White-tailed deer in Michigan, USA constitute a reservoir of M. bovis. White-tailed deer are a popular game species, and as such, represent a food animal to many hunters. BCG persistence in deer tissues could result in human exposure to BCG. Although non-pathogenic, BCG exposure could induce false positive skin test results, confounding the central component of public health surveillance for TB. The objective of the present study in white-tailed deer was to evaluate persistence of lipid encapsulated BCG after oral administration at 2 different dosages. Vaccine was not recovered at any time after oral consumption of a bait containing a single dose (1 x 10**8 CFU) of lipid encapsulated BCG. However, persistence was consistent in deer consuming 10 lipid encapsulated baits (1 x 10**9 CFU), with BCG recovered from at least one deer at 1, 3, 6, 9, and 12 months after consumption. Persistence of BCG was limited to lymphoid tissue and never found in samples of muscle collected at each time point. Although the risk of exposure to hunters is low, BCG persistence should be considered prior to field use in white-tailed deer.

Last Modified: 10/25/2014