Environment, Food and Rural Affairs CommitteeWritten evidence submitted by the Humane Society
1. This submission represents the views of Humane Society International/UK (HSI UK) on the subject of vaccination of badgers and cattle against bovine tuberculosis.
2. Background
Bovine tuberculosis, caused by infection with Mycobacterium bovis, is a notifiable disease of cattle. All UK cattle herds are subjected to compulsory testing, with animals which test positive for infection subject to compulsory slaughter and infected herds subject to movement restrictions. According to DEFRA figures,i 11.5% of cattle herds in England were under movement restriction during 2011, and 27,145 positive tested cattle had been slaughtered in 2012 to the end of September. The total cost to the public purse of the bovine tuberculosis control policy over the past 10 years is estimated at £500 million.
3. As well as infecting cattle, bovine tuberculosis is known to infect various other species, including badgers. Badger populations are thought to constitute a wildlife reservoir of Mycobacterium bovis.
4. In December 2011 the government published its Policy on Bovine TB and Badger Control in England,ii in which it described plans to license the culling of badgers in order to reduce populations by at least 70% for a period of four years in two pilot zones each of at least 150km2, and subsequently in up to 40 additional bovine TB affected areas. If fully rolled out, Natural England estimates that this could result in the killing of up to 130,000 badgers, and the reduction of England’s badger population by a third.iii Based on the results of the Randomised Badger Culling Trial,iv the government estimates that this could reduce the incidence of TB in cattle herds by an average of 12–16% within the culling zones nine years after culling commences.
5. Vaccination as a mechanism for the control of infection in populations is widely practised in domestic animals, wildlife and human populations.
6. Badger Vaccination
In March 2012 the Welsh Assembly Government, using the same scientific evidence, rejected badger culling and opted instead for a badger vaccination programmev in the west Wales Intensive Action Area using the injectable BCG badger vaccine which was licensed in 2010. By the end of the first vaccination “season” more than 1400 badgers were reported to have been vaccinated.vi
7. A number of groups and private individuals have also been vaccinating badgers in parts of England. The largest such project is the Badger Vaccine Deployment Project area in Gloucestershire operated by the Food and Environment Research Agency,vii which reported to have vaccinated 998 badgers during 2012. Indeed this is the last remaining project from 6, following the closure of five similar projects made early in the term of the current government as a cost-saving measure.
8. While it is as yet too early to measure any impact of badger vaccination on the incidence and prevalence of bovine TB in cattle in Wales, the Welsh experience, and the experience of groups in England where badger vaccines have been deployed, have shown that large scale vaccination of badgers is possible.
9. The results of the Randomised Badger Culling Trial showed that reactive badger culling increased, rather than reduced, the incidence of TB in cattle; and that while proactive culling reduced TB incidence in cattle in culled areas, this beneficial effect on cattle breakdowns was offset by an increased incidence of the disease in surrounding un-culled areas. The Independent Scientific Group responsible for the evaluation of the data concluded that this effect resulted from culling-induced changes in badger ecology and behaviour known as the perturbation effect.
10. A recent scientific field study conducted using free-living badgers over four years by Carter et al and published in the scientific journal PlosOneviii concluded that vaccination with BCG not only resulted in a direct protective effect on individual vaccinated badgers reducing by 76% the risk of free-living vaccinated badgers testing positive for progressive infection; but also in an indirect protective effect on unvaccinated badger cubs, with the risk of positive tests in unvaccinated cubs being reduced by 79% when more than a third of the adults in their social group had been vaccinated.
11. Vaccination of badgers using the current injectable vaccine therefore markedly reduces the prevalence and progression of infection in vaccinated badgers and their unvaccinated cubs, as well as eliminating the risks to cattle from badger perturbation that results from badger culling. Badger vaccination is therefore likely to prove a more effective long-term strategy for reducing the incidence and prevalence of bovine TB in badgers, and therefore for reducing the risk of transmission of bovine TB from badgers to cattle, than is culling.
12. The government should therefore adopt badger vaccination as a more effective long-term strategy to controlling bovine TB in badger populations than culling. Greater investment in the development of orally administered vaccines which could be fed to badgers in food bait should be given a high priority by government, since this will greatly facilitate the widespread use of vaccines with which to protect badgers from bovine TB and reduce the need for badgers to be trapped, and the associated costs. Research into orally-administered TB vaccines designed for use in wildlife has already shown promise in terms of controlling the spread of disease in Spanish wild boar,ix x and in brush-tail possums in New Zealand. In the meantime, government should encourage innovative programmes, including volunteer projects, to increase the deployment of injectable badger vaccines in areas of high risk for bovine TB.
13. Cattle Vaccination
While badger vaccines offer a more palatable and effective method of reducing the prevalence of bovine TB in badger populations, the main source of bovine TB in cattle remains other cows. Therefore safe, humane and effective methods of reducing the risk of transmission of bovine TB between cattle must be sought as a matter of urgency. The elimination of the disease in cattle will depend on the development and use of effective vaccines and sensitive, specific diagnostic tests that allow differentiation between vaccinated and infected animals.
14. These developments were recommended in the Krebs Report of 1997.
15. The BCG vaccine has reportedly shown a 56–68% protective efficacy in neonatally vaccinated calves,xi in small-scale trials conducted in Ethiopia. Larger-scale trials are needed to determine the impact that such levels of efficacy would have at a herd or population level. However, while the development of cattle vaccines with greater levels of efficacy and longevity should be a priority, there is every reason to suppose that the carefully planned, widespread use of the current BCG vaccine in cattle would significantly reduce the risk of transmission between cattle, and therefore the incidence and prevalence of infection in the national herd.
16. Vaccination of cattle against TB is currently prohibited by EU Directive 78/52/EEC, because the use of the BCG vaccine can interfere with the tuberculin skin test, which is recognised as the primary diagnostic test for TB in cattle. Vaccination with BCG produces a reaction to the tuberculin skin tests which subsides after approx. one year in >90% of vaccinated cattle according to DEFRA,xii following which the vaccinated animal will test negative.
17. In January 2012, the Animal Health Veterinary Laboratories Agency (AHVLA) submitted a dossier to the Veterinary Medicines Directorate (VMD)xiii for approval in principal of a Marketing Authorisation for the BCG-based cattle vaccine. According to the DEFRA website feedback was expected from the VMD “within a year”.
18. The AHVLA has developed a test for Differentiating Infected from Vaccinated Animals (DIVA test) which identifies a reaction to specific Mycobacterium bovis antigens not present in the BCG vaccine.xiv A positive test therefore indicates an infected animal; uninfected vaccinated animals should test negative.
19. In order to get EU acceptance the DIVA test will need to be accredited by the OIE (The World Organisation for Animal Health), this will also facilitate the trade in products from vaccinated cattle outside the EU.
20. There is a validation process to which the DIVA test must be subjected before an OIE application can be submitted. Once the application is submitted the approval process takes around four—five months.
21. The government should be doing all it can to ensure that the necessary permissions are obtained in order to allow for the DIVA test to be field-tested, and the validation process with OIE expedited. In parallel, the government should be working with its EU partners to ensure that the use of the BCG vaccine, alongside the DIVA test, will enable products from vaccinated, disease-free animals to be traded within the EU.
22. Public Acceptance
Vaccination programmes, for both cattle and badgers, will undoubtedly meet with far greater levels of public approval and acceptance than badger culling.
23. Instead of investing large amounts of public and private money in a controversial and unpopular badger culling policy, which will at best result in a marginal reduction in the incidence of bovine TB in cattle over the long term, government should instead focus its investment in biosecurity measures designed to reduce the risk of TB spreading among cattle and between cattle and badgers, and in the development of practical, safe and efficacious vaccination protocols for both cattle and badgers and the political environment which makes their use acceptable.
References
i http://www.defra.gov.uk/animal-diseases/a-z/bovine-tb/
ii http://www.defra.gov.uk/publications/files/pb13691-bovinetb-policy-statement.pdf
iii The impact of culling on badger (Meles meles) populations in England and measures to prevent their “local disappearance” from culled areas: Supplementary advice provided under the Protection of Badgers Act 1992
and Wildlife & Countryside Act 1981 (as amended). Natural England, July 2011.
iv http://archive.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/tb/isg/report/final_report.pdf
v http://wales.gov.uk/newsroom/environmentandcountryside/2012/120320vaccination/?lang=en
vi http://www.bbc.co.uk/news/uk-wales-20534842
vii http://www.fera.defra.gov.uk/wildlife/ecologyManagement/bvdp/
viii http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0049833
ix http://www.hindawi.com/journals/vmi/2012/978501/
x Beltran-Beck et al. (2012) Progress in Oral Vaccination against Tuberculosis in Its Main Wildlife Reservoir in Iberia, the Eurasian Wild Boar. Veterinary Medicine International. Article ID 978501, 11 pages, 2012. doi:10.1155/2012/978501
xi http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953002/
xii http://archive.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/tb/documents/vaccine_cattle.pdf
xiii http://animalhealth.defra.gov.uk/about/publications/ov/ov-newsletter/OV_newsletter_11.pdf
xiv Whelan A O, Clifford D, Upadhyay B, Breadon E L, McNair J, Hewinson G R, Vordermeier H M 2010. Development of a skin test for bovine tuberculosis for differentiating infected from vaccinated animals. J Clin. Micro. 48, 3716-3181.
January 2013