Badgers and bovineTB: Why the Government’s policy needs to change
Monday 10th February 2014
Badger culling should be dropped from Government plans and priority given to a strategic vaccination programme.
Our work on nature reserves and in partnership with farmers, vets and other landowners has demonstrated that vaccination is a practical, cost-effective option
The Wildlife Trusts are urging the Government to drop culling from its bTB strategy and commission an independent expert review to examine how badger vaccination - alongside a comprehensive package of cattle measures: better biosecurity, stricter movement controls, improved TB testing and development of a cattle vaccine - can better tackle bovine TB.
Badger vaccination is a viable option and a strategic programme could make a real contribution to reducing levels of bTB infection: vaccinating a third of adult badgers reduces the risk to unvaccinated cubs by 79%; ‘herd immunity’ is achieved in five years, as infected animals die and the proportion of vaccinated individuals increases; it offers 54-76% reduction in risk of badgers testing positive for bTB. The injectable vaccine has been available since March 2010.
Paul Wilkinson, Head of Living Landscape for The Wildlife Trusts, said:
“Organisations, including The Wildlife Trusts, are already running badger vaccination programmes, with more than 180 trained and certified lay vaccinators in England and Wales. Our work on nature reserves and in partnership with farmers, vets and other landowners has demonstrated that vaccination is a practical, cost-effective option.
“The problem which must be addressed is bovineTB not badgers. We strongly opposed the pilot badger culls and will continue to oppose any proposals for more. The scale of culling of a native mammal, which is a valuable part of the ecosystem, is simply not justified by the small potential reduction in bovine TB incidence in cattle.”
Most badgers are not infected. Just 5.7% of bTB outbreaks are caused by badgers. These initial infections are amplified by cattle to cattle transmission. 83% of badgers culled during the RBCT were bTB free. None of the badgers culled in 2013 were tested for bTB.
The pilot badger culls in Somerset and Gloucestershire both failed to meet the key test of ‘effectiveness’. The removal of at least 70% of the estimated badger population in the six-week licence period was not achieved. Despite a three week extension in Somerset and five weeks in Gloucestershire, the percentages achieved were 65% and 39% respectively. It is possible for the bovine TB problem to have been made worse, due to the ‘perturbation effect’. This causes individuals to range beyond their usual territory and come into contact with neighbouring animals, increasing the risk of disease transmission.
Notes for editors:
For more information and to see what action you can take, see www.wildlifetrusts.org/badgers-and-bovineTB
Find out about badger vaccination and donate to a Wildlife Trust vaccination project at www.wildlifetrusts.org/appeals/badgers
The following list of references is online at www.wildlifetrusts.org/badger-refs
Most badgers aren’t infected
The Randomised Badger Culling Trial (RBCT) is the largest study of bTB in badgers ever undertaken. Of almost 8,900 badgers culled in TB hotspots between 1998 and 2005, just 16.6% were found to be TB positive - meaning that 83.4% were TB free. The RBCT was designed, overseen and analysed by the Independent Scientific Group on Cattle TB, whose Final Report states: “4.21 The overall prevalence of M. bovis infection in road-killed badgers (15%) was similar to that recorded in proactively culled badgers during the same time period (16.6%; data in Table 4.8). There was substantial variation in prevalence between counties and between years.” Final Report of the Independent Scientific Group on Cattle TB
How many TB outbreaks are caused by badgers?
Further analysis and modelling of data from the RBCT indicated that “...only 5.7% of the transmission [of bTB] to cattle herds is badger-to-cattle with the remainder of the average overall contribution from badgers being in the form of onward cattle-to-cattle transmission.”
Donnelly, C.A. & Nouvellet, P. (2013) The contribution of badgers to confirmed tuberculosis in cattle in high-incidence areas in England. PLOS Currents Outbreaks. 2013 Oct 10. Edition 1
The badger BCG vaccine is effective
“Intramuscular injection of BCG reduced by 76% the risk of free-living vaccinated individuals testing positive to a diagnostic test combination to detect progressive [bTB] infection. A more sensitive panel of tests for the detection of infection per se identified a reduction of 54% in the risk of a positive result following vaccination.”
Carter et al. (2012) BCG Vaccination Reduces Risk of Tuberculosis Infection
in Vaccinated Badgers and Unvaccinated Badger Cubs. PLoS ONE 7(12): e49833
“In a clinical field study, BCG vaccination of free-living badgers reduced the incidence of positive serological [bTB] test results by 73.8 per cent. In common with other species, BCG did not appear to prevent infection of badgers subjected to experimental challenge, but did significantly reduce the overall disease burden. BCG vaccination of badgers could comprise an important component of a comprehensive programme of measures to control bovine TB in cattle.” Chambers et al. (2010) Bacillus Calmette-Guérin vaccination reduces the severity and progression of tuberculosis in badgers Proc. R. Soc. B 2011 278
Vaccination reduces risk to unvaccinated cubs
“...the risk of unvaccinated badger cubs, but not adults, testing positive to an even more sensitive panel of diagnostic tests decreased significantly as the proportion of vaccinated individuals in their social group increased. When more than a third of their social group had been vaccinated, the risk to unvaccinated cubs was reduced by 79%.” Carter et al. (2012) BCG Vaccination Reduces Risk of Tuberculosis Infection in Vaccinated Badgers and Unvaccinated Badger Cubs. PLoS ONE 7(12): e49833
Vaccination leads to herd immunity
“Most badgers have a lifespan of just 3 to 5 years and the annual population turnover of the UK badger population is estimated to be 30%, therefore we expect that it will take 5 years to vaccinate a sufficient number of naive badgers to achieve herd immunity and reduce TB incidence within a badger population.” AHVLA vaccination FAQs
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