Persistence of Mycobacterium bovis Bacillus Calmette-Guerin (BCG) in White-tailed Deer (Odocoileus virginianus) After Oral or Parenteral Vaccination

Authors: Palmer, Mitchell; Thacker, Tyler; Waters, Wade; ROBBE-AUSTERMAN, SUELEE - Animal And Plant Health Inspection Service (APHIS); SEMAKALENG, LEBEPE-MAZUR - Animal And Plant Health Inspection Service (APHIS); HARRIS, N - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Zoonoses and Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2010
Publication Date: 12/1/2010
Citation: Palmer, M.V., Thacker, T.C., Waters, W.R., Robbe-Austerman, S., Semakaleng, L., Harris, N.B. 2010. Persistence of Mycobacterium bovis Bacillus Calmette-Guerin (BCG) in White-tailed Deer (Odocoileus virginianus) after oral or parenteral vaccination. Zoonoses and Public Health. 57(7-8):e206-e212.

Interpretive Summary: Mycobacterium bovis is the cause of tuberculosis in cattle and a serious human pathogen, most commonly contracted through consumption of unpasteurized dairy products. To control this disease, many countries have developed bovine tuberculosis control programs. Although relatively successful, efforts are hindered in some regions by spillover of M. bovis from infected wildlife to cattle. Such is the case in the United States where spillover of M.bovis from free-ranging white-tailed deer to cattle occurs. One approach to control such interspecies transmission is vaccination of wildlife. The human vaccine M.bovis BCG has been shown to reduce disease severity in white-tailed deer; however, vaccine persisted within tissues longer than expected. Consumption of venison containing BCG by hunters may present a public health concern as BCG exposure, although unlikely to cause disease, could cause false positive tuberculin skin test results. To further examine BCG persistence, forty-two white-tailed deer were vaccinated orally or subcutaneously (SC) with BCG. Three deer from each group were euthanized and examined at time periods ranging from 2 weeks to 11 months after vaccination. BCG was recovered from orally vaccinated deer as late as 3 months after vaccination, while BCG persisted in SC vaccinated deer for as long as 9 months. Prolonged persistence of BCG was seen only in lymph nodes and at no time was BCG isolated from meat. Although vaccine persistence was noted, especially in SC vaccinated deer, the distribution of culture positive tissues makes human exposure through consumption unlikely.

Technical Abstract: Mycobacterium bovis is the cause of tuberculosis in cattle and a serious zoonotic pathogen, most commonly contracted through consumption of unpasteurized dairy products. To control this zoonosis, many countries have developed bovine tuberculosis eradication programs. Although relatively successful, efforts are hindered in some regions by spillover from wildlife reservoirs of M.bovis to cattle. Such is the case in the United States where spillover of M.bovis from free-ranging white-tailed deer to cattle occurs. One approach to control such interspecies transmission is vaccination of wildlife. The human vaccine M.bovis BCG has been shown to reduce disease severity in white-tailed deer; however, vaccine persistence within tissues has also been noted. Consumption of venison containing BCG by hunters may present a public health concern as BCG exposure, although unlikely to cause disease, could cause false positive tuberculin skin test results. To further examine BCG persistence, forty-two white-tailed deer were vaccinated orally or subcutaneously with BCG. Three deer from each group were euthanized and examined at time periods ranging from 2 weeks to 11 months after vaccination. BCG was recovered from orally vaccinated deer as late as 3 months after vaccination, while BCG persisted in SC vaccinated deer for as long as 9 months. Prolonged persistence of BCG was seen only in lymphoid organs and at no time was BCG isolated from meat. Although vaccine persistence was noted, especially in SC vaccinated deer, the distribution of culture positive tissues makes human exposure through consumption unlikely.