Correspondence

Bovine tuberculosis: Badger-cull targets unlikely to reduce TB

Two months ago, the government-advice body Natural England approved further licensed badger culls in parts of the United Kingdom in 2015. The aim is to reduce local badger densities by at least 70% to prevent the spread of tuberculosis (TB) to cattle (see go.nature.com/iiutvj). On the basis of the government's badger-population estimates, we calculate that these culls are unlikely to achieve the necessary reduction.

The latest minimum cull numbers derive from the lower 95% confidence bounds on population size estimates. For example, licensees in Dorset are required to kill at least 615 badgers in a population estimated at 879–1,547 animals (95% confidence interval). Killing this number would give an estimated population reduction of between 39.8% and 70% (95% confidence interval).

Equivalent confidence intervals for the 2015 (third annual) Somerset and Gloucestershire culls are, respectively, 50.8–70% and 54–70% relative to the baseline population estimates. It is therefore unlikely that a 70% or greater reduction can be attained by these minimum cull numbers, assuming that the population estimates are accurate.

Evidence from a randomized controlled trial shows that better prospects for the control of cattle TB are offered by badger populations that are either reduced by more than 70% or left undisturbed — and potentially vaccinated (C. A. Donnelly et al. Nature 439, 843–846; 2006). The choice depends on a range of epidemiological, economic, social and ecological factors.

Notes

Author information

Affiliations

  1. Imperial College London, UK.

    • Christl A. Donnelly
  2. Institute of Zoology, London, UK.

    • Rosie Woodroffe

Authors

  1. Search for Christl A. Donnelly in:

  2. Search for Rosie Woodroffe in:

Competing interests

C.A.D. and R.W. were members of the Independent Scientific Group on Cattle TB that designed, oversaw and analysed the Randomised Badger Culling Trial. C.A.D. is a consultant on the Defra-funded project ‘Developing a surveillance system to report TB in cattle herds exposed to badger control in England - SE3131’. R.W. is a principal investigator, and C.A.D. is co-investigator, on the Defra-funded project ‘A study to examine the interactions between cattle and badgers - SE3046’.

Corresponding author

Correspondence to Christl A. Donnelly.

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.