Bovine Tuberculosis and Badgers: Should we kill them all?

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“Human and livestock diseases can be difficult to control where infection persists in wildlife populations. Control of bovine tuberculosis (bTB) in British cattle is complicated by the maintenance of Mycobacterium bovis (the causative agent of bTB) in badgers, acting as reservoirs of infection. Although over 20 000 badgers were culled to control bTB between 1975 and 1997, the incidence of bTB in cattle has substantially increased in parts of Great Britain in recent decades. Our case-control study, involving 1208 cattle herds, provides further evidence of the detrimental effect of localized reactive badger culling in response to the disclosure of a confirmed bTB herd breakdown in cattle. The presence of any reactive badger culling activity and increased numbers of badgers culled in the vicinity of a herd were associated with significantly increased bTB risk, even after adjusting for other important local risk factors. Such findings may partly explain why some earlier localized approaches to bTB control were ineffective.” [1]

The abstract above, from a recent study carried out by Imperial College London’s MRC Centre for Outbreak Analysis and Modelling, is but one part to an ever expanding criticism of the Government’s plans to cull badgers.

The Conservative Secretary of State for Environment, Food and Rural Affairs – Mrs Caroline Spelman – has revealed that the licensed culling of Badgers will be piloted next spring, with wider implementation in 2013 [2] so long as consultation of the methodology does not throw up major obstacles.

Last year about 25,000 individual cattle had to be slaughtered after they were found to have developed Bovine Tuberculosis, at the cost of £90,000,000 to the tax payer. Bovine Tuberculosis affects cattle across the country, but the West and South West of England are particularly prone to the disease – last year up to 23% of herds in these areas had limitations placed on their movement because of Bovine TB [3] .

The severity of the disease, and the proven link between Badgers and its spread has caused concerned farmers to call for this culling for years It is perhaps this pressure which is convincing the government to go ahead with plans for the cull next year, despite questions being asked as to the effectiveness of these measures.

In the 1990’s, professor Lord John Kerbs was the government advisor and supervised the scientific review which found that the link between Badgers and Bovine TB; this was the original proponent of trial culls. The trail he called for was implemented and the results of the 10-year “randomised badger culling trials” showed that widespread, highly coordinated culls requiring the destruction of many thousands of badgers resulted in a reduction in new infections in local cattle herds of about 12 – 16%. This proves that culls would reduce the spread of Bovine TB and has further fuelled farmers calls for the implementation of the culls.

However, Lord Krebs says this trial evidence should be interpreted as an argument against culling. “You cull intensively for at least four years, you will have a net benefit of reducing TB in cattle of 12% to 16%. So you leave 85% of the problem still there, having gone to a huge amount of trouble to kill a huge number of badgers. It doesn’t seem to be an effective way of controlling the disease.” [4]

The author of the research paper cited above, Christl A. Donnelly, spoke today on BBC Radio 4’s Material World explaining the findings of the paper. Whilst it found that wide spread repeated culling reduced the spread of TB within the culling area, it had a detrimental effect on farms up to 2 km outside of the culling area. This is because Badgers are a territorial and social species that will defend the territory of the Badger society. Once the majority of a Badger society is destroyed the survivors abandon that territory and ‘scatter’, wonder far and wide, indirectly spreading the disease as they go. The only way to truly ensure culling reduces Bovine TB would be almost reduce the entire badger population in the culling area so to prevent this spread outside of the culling zone, known as ‘perturbation’.

This presents a three way tension between the potential benefit to the herds inside the culling area, the detrimental effects outside, and the cost effectiveness of culling to the potential benefit of reduced TB for cattle herds. On top of this many animal welfare groups are morally strongly against the extermination of thousands of wild badgers to potentially help domesticated cattle, and this type of extreme environmental engineering. Furthermore, when one type of wild animal is removed from an eco system on such a large scale it often has unforeseen and sometimes immense ramifications for that eco system – upsetting the natural balance.

The ‘culling’ in the trial was conducted by cage trapping the badgers and then shooting them through the head to minimise animal welfare concerns by ensuring they died as quickly and painlessly as possible. Due to the huge cost of these methods, the government instead plans to use an, as of yet, untested method of “controlled shooting” by trained marksmen as the badgers roam free at night [5]. Farming groups that desire a badger cull in their area would have to pay for these marksmen themselves, causing no additional cost for the government and hopefully reducing TB and the expense it causes the tax payer each year.

The other option, which has been rejected by the government due to the expense, would be vaccinating Badgers; currently the vaccination would have to be administered by cage trapping the Badgers, injecting them, and letting them go – at considerable cost. The hunt is on to develop both a vaccination for the cattle, something that is currently unavailable, or an orally active vaccination for badgers that could be introduced into their food allowing them to eat it and become vaccinated at their own leisure (a cheap solution).

Due to the fact that both scientists and animal welfare campaigners are against the policy of Conservative minister Caroline Spelman, it will be interesting to see if the government continues with its plans and if they manage to pass outside consultation.

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[1] Flavie Vial and Christl A. Donnelly ‘Localized reactive badger culling increases risk of bovine tuberculosis in nearby cattle herds’, Biol Lett 2011 : rsbl.2011.0554v1-rsbl20110554. – Prof Christl Donnelly was deputy chair of the Independent Scientific Group on Cattle TB (1998 to 2007), through which she was jointly responsible for the design and analysis of the randomized study of badger culling strategies, a field trial conducted over 3,000km2 costing roughly £7million per annum.

[2] http://www.bbc.co.uk/news/uk-14204236

[3] Information supplied by Christl A. Donnelly in an interview with BBC radio 4’s Material World

[4]http://www.guardian.co.uk/environment/2011/jul/11/badger-culling-ineffective-krebs?INTCMP=SRCH

[5]http://www.bbc.co.uk/news/uk-14204236

  • http://twitter.com/Whquick William Henry Quick

    Would this article not be better suited the the category health and education as it’s about the health of cattle and government plans to attempt to reduce the risk of food becoming infected with Bovine TB?