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Shedding of Mycobacterium bovis in the nasal mucus of cattle infected experimentally with tuberculosis by the intranasal and intratracheal routes
  1. T. McCorry, PhD, BSc1,
  2. A. O. Whelan, PhD, BSc2,
  3. M. D. Welsh, PhD, BSc3,
  4. J. McNair, PhD, BSc3,
  5. E. Walton, HNC3,
  6. D. G. Bryson, PhD, BVM, MRCVS3,
  7. R. G. Hewinson, DPhil, BSc2,
  8. H. M. Vordermeier, PhD, BSc2 and
  9. J. M. Pollock, PhD, BVM&S, MRCVS3
  1. 1Department of Veterinary Science, Queen’s University of Belfast, Stoney Road, Stormont, Belfast BT4 3SD
  2. 2TB Research Group, Veterinary Laboratories Agency – Weybridge, New Haw, Addlestone, Surrey KT15 3NB
  3. 3Veterinary Sciences Division, Department of Agriculture and Rural Development, Stoney Road, Stormont, Belfast BT4 3SD
  1. Correspondence to Dr Welsh


Four groups of six calves were infected experimentally with either a low dose of approximately 104 colony-forming units (cfu) or a high dose of approximately 106 cfu of Mycobacterium bovis. Each dose was delivered by the intranasal and intratracheal routes. More severe disease was observed in the groups inoculated with the high dose. Visible lesions were identified in 21 of the 24 animals, all of which also gave positive skin tests and interferon-γ (IFN-γ) responses. Nasal shedding was detected in 15 of the 24 animals and the frequency of shedding was influenced by both the route and the dose of infection; no shedding was observed in the group infected intratracheally with the low dose. Two of the 15 confirmed shedders had no visible lesions at postmortem examination; both of these calves gave IFN-γ responses but only one was skin test positive.

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