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Efficacy of oral BCG vaccination in protecting free-ranging cattle from natural infection by Mycobacterium bovis

journal contribution
posted on 2023-05-03, 09:52 authored by Graham Nugent, Ivor Yockney, Jackie Whitford, Frank Aldwell, Bryce BuddleBryce Buddle
Vaccination of cattle against bovine tuberculosis could be a valuable control strategy, particularly in countries faced with intractable ongoing infection from a disease reservoir in wildlife. A field vaccination trial was undertaken in New Zealand. The trial included 1286 effectively free-ranging cattle stocked at low densities in a remote 7600 ha area, with 55% of them vaccinated using Mycobacterium bovis BCG (Danish strain 1311). Vaccine was administered orally in all but 34 cases (where it was injected). After inclusion, cattle were exposed to natural sources of M. bovis infection in cattle and wildlife, most notably the brushtail possum (Trichosurus vulpecula). Cattle were slaughtered at 3–5 years of age and were inspected for tuberculous lesions, with mycobacteriological culture of key tissues from almost all animals. The prevalence of M. bovis infection was 4.8% among oral BCG vaccinates, significantly lower than the 11.9% in non-vaccinates. Vaccination appeared to both reduce the incidence of detectable infection, and to slow disease progression. Based on apparent annual incidence, the protective efficacy of oral BCG vaccine was 67.4% for preventing infection, and was higher in cattle slaughtered soon after vaccination. Skin-test reactivity to tuberculin was high in vaccinates re-tested 70 days after vaccination but not in non-vaccinates, although reactor animals had minimal response in gamma-interferon blood tests. In re- tests conducted more than 12 months after vaccination, skin-test reactivity among vaccinates was much lower. These results indicate that oral BCG vaccination could be an effective tool for greatly reducing detectable infection in cattle.

History

Rights statement

© 2017 Elsevier B.V. All rights reserved.

Language

  • English

Does this contain Māori information or data?

  • No

Publisher

Elsevier

Journal title

Veterinary Microbology

ISSN

0378-1135

Citation

Nugent, G., Yockney, I. J., Whitford, J., Aldwell, F. E., & Buddle, B. M. (2017). Efficacy of oral BCG vaccination in protecting free-ranging cattle from natural infection by Mycobacterium bovis. Veterinary Microbology, 208, 181–189. doi:10.1016/j.vetmic.2017.07.029

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