Bovine tuberculosis (TB) in cervids remains a significant problem affecting farmed herds and wild populations. Traditional skin testing has serious limitations in certain species, whereas emerging serological assays showed promising diagnostic performance. The recently developed immunochromatographic dual-path platform (DPP) VetTB assay has two antigen bands, T1 (MPB83 protein) and T2 (CFP10/ESAT-6 fusion protein), for antibody detection. We evaluated the diagnostic accuracy of this test by using serum samples collected from groups of white-tailed deer experimentally inoculated with Mycobacterium bovis, M. avium subsp. paratuberculosis, or M. bovis BCG Pasteur. In addition, we used serum samples from farmed white-tailed deer in herds with no history of TB, as well as from free-ranging white-tailed deer culled during field surveillance studies performed in Michigan known to have bovine TB in the wild deer population. The DPP VetTB assay detected antibody responses in 58.1% of experimentally infected animals within 8 to 16 weeks postinoculation and in 71.9% of naturally infected deer, resulting in an estimated test sensitivity of 65.1% and a specificity of 97.8%. The higher seroreactivity found in deer with naturally acquired M. bovis infection was associated with an increased frequency of antibody responses to the ESAT-6 and CFP10 proteins, resulting in a greater contribution of these antigens, in addition to MPB83, to the detection of seropositive animals, compared with experimental M. bovis infection. Deer experimentally inoculated with either M. avium subsp. paratuberculosis or M. bovis BCG Pasteur did not produce cross-reactive antibodies that could be detected by the DPP VetTB assay. The present findings demonstrate the relatively high diagnostic accuracy of the DPP VetTB test for white-tailed deer, especially in the detection of naturally infected animals.
Mycobacterium bovis, the cause of tuberculosis (TB) in cattle, can also infect a broad range of other mammalian host species, including cervids. Free-ranging deer are known to play a role as wildlife reservoirs of M. bovis infection (1, 2), whereas farmed deer are reportedly involved in disease transmission to cattle (3, 4) and to humans (5, 6). In the last decade, M. bovis outbreaks in captive cervids have been increasingly found in the United States, including multiple herds of white-tailed deer (Odocoileus virginianus) in Michigan, elk (Cervus canadensis) in Indiana, a mixed herd of red deer (Cervus elaphus) and fallow deer (Dama dama) in New York, and a farm of elk and fallow deer in Nebraska (7-9).In captive cervids, bovine TB control relies primarily on intradermal tuberculin testing and more rarely on slaughter surveillance. Skin test procedures, however, have not been fully validated for use in various cervid species. These limitations were clearly demonstrated in the recent M. bovis outbreak in farmed elk and fallow deer in Nebraska, where only 3/28 animals that had gross lesions and produced positive culture results were reactors in the single c...