Comment: Bovine TB and badgers
(Microbiology Today Aug 07 by Chris Cheese
man)
The culling of badgers to control the spread of bovine tuberculosis has been going on for over 30 years. Chris Cheeseman reviews the effectiveness of this strategy, in the light of a new study.
The study of wildlife ecology is a fascinating subject, where processes in one part of the natural system can have profound effects on other, apparently unconnected components. Ecological processes impact on pathogen dynamics, particularly in wild animal populations, and their understanding can be of crucial importance in developing effective disease management strategies. Bovine tuberculosis (bTB) is a case in point; this is a serious disease problem which costs taxpayers and farmers a great deal of money. While the human health risks are minimal, there is a potential for human infection and the impact on the farming industry is significant. . Badgers were first implicated in the spread of bTB to cattle herds in southern England in the 1970s: since then further evidence has emerged to support the contention that badgers are indeed involved. The extent of their involvement, however has always been unclear. Nevertheless, badger culling has often been part of historical strategies to control the potential for spread to cattle, first by gassing setts and later by various strategies involved trapping and shooting. There is currently a debate as to whether badger culling should once again form part of the control strategy for this disease.
Back in the early 1980s a handful of ecologists ventured to suggest that it was possible that the impact of culling itself on the behaviour of badgers could potentially increase the risk of spreading disease. In 1996 an independent review by Sir John Krebs recommended a field trial, and a study was designed whereby two potential culling policy options – ‘proactive’ and ‘reactive’ culling of badgers – could be scientifically assessed. Implementation of what has been one of the largest field experiments ever undertaken, at a cost to taxpayers of £50 million, was the responsibility of the Independent Scientific Group on CattleTB chaired by Professor John Bourne. After nearly 10 years of work, involving meticulous attention to scientific rigour, the ISG’s report, Bovine TB: The Scientific Evidence, has now been published. In summary, the ISG conclude that neither the proactive or reactive culling of badgers can be recommended as a means of controlling bTB in cattle. Reactive culling, where badgers were trapped on and around farms where TB outbreaks had occurred, led to an overall increase in cattle TB of approximately 26%. Proactive culling, where the strategy was to trap as many badgers as possible annually in cattle TB hot-spots, resulted in a 23% reduction in cattle TB in the core of the culled area, while there was an increase of similar magnitude on the edge, thus negating any potential benefits over the time and scale of the study. These somewhat counter-intuitive negative effects of culling were explained by what has been termed the ‘perturbation effect’ , which is simply the disruption of the stable social structure typically found in undisturbed badger populations, leading to increased movement and enhanced contact, both between badgers and cattle. Indeed, it is entirely plausible that past culling policies have exacerbated the spread of bTB.
As the ISG’s results have emerged, they have been challenged, mostly from the farming and veterinary communities. Some of the criticism claimed that the trial was scientifically compromised. In response the ISG have made clear that the trial design, field activities , data collection and management, data analysis and other aspects of their work have been subjected to ongoing independent audit. The results of the trial have been subjected to the rigours of peer review, prior to being published in some of the most prestigious and demanding international scientific journals. Another criticism has centred on the charge that not enough badgers were killed, and that if badgers were gassed in their setts, for example, the positive effects of culling would increase and the negative effects would diminish. Trapping efficiency in the trial was high and consistent with design expectations, and even if more badgers could have been killed, there is no evidence to suggest that this would have resulted in additional benefits in terms of decreased cattle breakdowns. The existing control strategy for this disease includes regular herd testing to identify infection in cattle, combined with the slaughter of reactors. In addition, new pre-movement testing requirements for cattle have been introduced, reflecting the scientific evidence that more rigorous application of cattle-based measures plays a central role in the control of this disease. Other work is underway to examine vaccines and improved farm husbandry to reduce disease transmission risks from wildlife. Even putting aside arguments about wildlife conservation in a country where our indigenous fauna is under ever increasing pressure, the conclusion from the recent badger culling trial is profoundly simple: we cannot disrupt badger populations by culling without potentially making the cattle TB problem worse.
Chris Cheeseman
Central Science Laboratory (c.cheeseman@csl.gov.uk)
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Quotes from the Independent Scientific Groups final report
Chairman’s Overview (Professor John Bourne CBE MRCVS):-
Point 9: “After careful consideration of all the RBCT ( Random Badger Control Trials) and other data presented in this report, including an economic assessment, we conclude that badger culling cannot meaningfully contribute to the future control of cattle TB in Britain.”
Point 13: “ The ISG recognises the difficulties faced by Government in implementing control strategies without full industry cooperation. It is unfortunate that agricultural and veterinary leaders continue to believe, in spite of overwhelming scientific evidence to the contrary, that the main approach to cattle TB control must involve some form of badger population control. It is our hope that Defra will embrace new scientific findings, and communicate these to these stakeholders in ways that encourage acceptance and participation.”
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Article for Mammal News
Badgers and TB (by Warren Cresswell )
There can be few wildlife disease management issues in Britain that have persisted for longer, or followed a more circuitous path, than the badger TB saga. It is now 36 years since badgers were first implicated in this zoonotic disease (i.e. affecting both man and animals), and despite a variety of strategies to control the problem by culling badgers, the number of cattle herds affected is higher now than at any time since Britain was declared “attested” nearly 50 years ago.
That the badger is implicated in the complex epidemiological picture is beyond doubt. The real conundrum centres around what to do about their involvement. At the Cranbrook Lecture given during the Mammal Society AGM in April this year, Chris Cheeseman gave members a clear and comprehensive summary of the information collected during many years of scientific endeavour. Indeed, I should declare my own contribution to the badger TB research programme, which included my postdoc study of badger reproductive biology from carcasses taken during culling operations in the early 1990s. There has been a massive scientific research programme over the years, including the work of a succession of PhD students (several of whom are Mammal Society members and personal friends). This culminated in the Randomised Badger Culling Trial (RBCT), which led to the publication of a report by the Independent Scientific Group, appointed by Defra to design, oversee and direct the RBCT, in June 2007. During the course of the RBCT, I was employed in a professional capacity as an auditor of the field work programme. This included assessment of the procedures of surveying, trapping, and badger social group delineation.
This audit highlighted some discrepancies with regard to sett classification and the finding/recording of smaller setts, but found that, broadly, the RBCT was founded on relatively sound survey data. The audit report also presented recommendations to help improve the interpretation of the relationship between badger density, social group density and the various epidemiological elements of the Trail analyses.
The main findings of the RBCT had already been published in the scientific literature, so the report of the Trial itself contained no surprises. As Chris Cheeseman elaborated in his Cranbrook Lecture, badger culling led to both positive and negative effects. Before proceeding to explain further the scientific results and conclusions, it is important to remember that this huge and expensive trial (costing at least £50 million) was scientifically designed. The results have been subjected to independent audit, peer review, and have been published in high quality, international journals.
Essentially, reactive culling, carried out on and around farms after TB outbreaks had occurred, led to a 27% increase in the incidence of TB in cattle. Proactive culling, where annual culling was carried out over the entire treatment area irrespective of the occurrence of TB in cattle, resulted in an overall 23.2% reduction in cattle TB incidence in the core of the culled area. However, this improvement in the core of the treatment area was accompanied by an increase of 24.5% in the incidence of cattle TB on the periphery of the culled area.
A large number of scientific papers have now been published which present convincing evidence that this negative edge effect was due to the ‘perturbation’ of badger populations caused by culling. Culling leads to disruption of the badgers normally stable social structure and the remaining animals move around more. In fact it has been shown that not only can badger culling cause TB to spread and lead to an increase in incidence in cattle, it leads to a rise in prevalence in the residual badger population. Moreover, these findings have now been corroborated by molecular genetic analysis of the badgers culled during the proactive treatment of the RBCT (adopted as a realistic basis for possible future policy). These genetic studies revealed that infected badgers move more than uninfected individuals. It all adds up: the findings of the RBCT were not only statistically valid and consistent but they make biological sense, and it is this totality of data that is so convincing. It is pretty clear now that DEFRA’s approach to badger culling prior to the RBCT made the situation worse, and for someone who sat through innumerable (and interminable) meetings of the Government’s old Consultative Panel on Badgers, Cattle and Bovine TB, suggesting this very thing, this is both particularly galling and in no way a surprise. More than this, though, badger culling, in any form, certainly as it has been performed in the RBCT, is likely also to actually make matters worse.
It was entirely predictable then that the Independent Scientific Group concluded in their report that ‘badger culling is unlikely to contribute usefully to the control of cattle TB in Britain’.
So, it seems we now have one possible explanation as to why the disease in cattle has got steadily worse over the years: the small-scale, piece-meal culling operations carried out by MAFF/DEFRA in the past actually exacerbated the problem. Another contributory factor is the apparent inadequacy of the cattle TB testing programme.
Consider these statistics: In Britain as a whole, over 80% of cattle are never tested; 11%-23% of cattle in multiple reactor herds (three or more tuberculin skin test reactors) are infected but evade diagnosis by the skin test (the majority of these animals remain undiagnosed at follow-up testing by which time other animals also show-up positive); multiple reactor herds constitute 40% of breakdowns herds in the South West region (Bourne et al, 2007). There is also overwhelming evidence for disease spread into new areas by the movement of infected cattle (Bourne et al, 2007), adding, in several parts of the country, to the tragedy of the previous FAM outbreak. The ISG clearly believed this highlights the fundamental importance of cattle to cattle transmission and therefore the priority should be to gain better control of the disease in cattle. Their report concluded that ‘substantial reductions in cattle TB incidence could be achieved by improving cattle-based control measures’.
Since the ISG’s report was published in June, things went relatively quiet over the summer, save for occasional somewhat strident, non-scientifically based criticism of the report from the farming and veterinary communities. They, it seems, still think the answer lies in culling badgers, regardless of the independent scientific evidence. It has to be said that many of the proponents of culling are individuals who held office in MAFF/DEFRA, and were involved in, if not responsible for, the failed culling policies of the past. Their argument centres around the claim that insufficient numbers of badgers were killed (10,979 were trapped in total during the RBCT) in the areas trapped.
In fact, despite the constraints on land access, capture methods being restricted to cage trapping and the vagaries of the weather, the overall culling efficiency averaged 68% after just the initial proactive culls, and culling was repeated for an average of five years across the RBCT triplets. Trial data indicate that about 75% of badgers are removed allowing for immigration into culled areas and population re-growth - this is consistent with about an 80% badger culling efficiency, which met with trial design expectations. The one thing upon which everyone seems to agree is that if badgers were eliminated over large areas, preferably bounded by the sea and effectively covering the entire south west land mass, then the badger contribution to the cattle TB problem will also be substantially reduced. However, as the overall contribution by badgers is unlikely to exceed 30-40%, even in the centre of TB hot-spots, there will still be a huge problem after large chunks of Britain have been denuded of a ‘key’ indigenous wildlife species. In reality it is unlikely that any proposed culling areas will be isolated by the sea, with the inevitable result that there will be winners and losers amongst farmers.
And the cost? To quote again from the ISG’s report: ‘if a proactive culling strategy along the lines of the RBCT were to be adopted it would cost over £1 million for every £27,000 saved in breakdowns, clearly economically indefensible’. Remember too that this would be taxpayers’ money, the farming unions having made it clear that the farming community does not wish to pick up the tab. No doubt there were many taxpayers among the 47,000 individuals (an all-time record) who responded to the Government’s consultation on badger culling in 2006. No less than 96% of respondents were opposed to culling. Similarly, a wide range of informed organisations, the Mammal Society among them, responded to this consultation, indicating their opposition to culling.
So you would think that the way forward was crystal clear to our politicians. Not so.
A significant recent development was the latest in a series of hearings on the TB issue by the House of Commons Environment, Food and Rural Affairs Select Committee. Two days before the meeting on the 24th October, Sir David King, the Government’s Chief Scientific Adviser, published his own report on “Bovine Tuberculosis in Cattle and Badgers” (King, D., 2007). This made headline news on the BBC and in the media, with the typical headline ‘Chief Scientist Urges Badger Cull’.
Now you have to ask, firstly, why was it necessary for the Chief Scientist to write a report, when the Government had commissioned an enormously expensive scientific trial and appointed a group of eminent, independent scientists to direct the science and advise on the results? Secondly, why was the King report published just two days before the Select Committee hearing in October, when it was in the hands of the Government back in July? Finally, after a mere 10 hours in preparation by group of ‘experts’ (by Sir David King’s own admission), why did the report fail to recognise the major problem that still remains in cattle TB testing, and why did they take the diametrically opposed view that ‘the removal of badgers could make a significant contribution to the control of cattle TB’? I will leave you, fellow mammalogists, to reach your own conclusion.
Fortunately there is still a glimmer of hope that common sense and good science will prevail. DEFRA have said that they will not be making any decision on culling soon. As I write there is considerable debate going on around the report by Sir David King, with a number of leading scientists, including the RBCT’s Chief Auditor appointed by DEFRA, heavily criticising its scientific validity: ‘unbalanced’, ‘inexpert’, ‘superficial’, ‘selective’, ‘pervaded by errors’ are some of the descriptive terms used. Hard on the heals of the King report came an editorial in the Journal ‘Nature’, which I commend to you as particularly insightful comment on this issue. The essence of the editorial is summarised by the statement: ‘the mishandling of the issue by David King, the UK government’s chief scientific adviser, is an example to governments of how not deal with independent scientific advice, once it has been solicited and received. (Nature 2007)
Sir David King’s alternative view, which of course has not been subjected to peer review nor published in the scientific literature, is meat and drink to the farming organisations who are reiterating their siren calls for culling. One very obvious impasse is that while farmers do not want to pay for a cull, neither does DEFRA. It would be as well for all involved to consider the immense practical difficulties of a culling policy: the economics; the necessary co-ordination of effort; the very real threat of direct action against culling operations; and the issue of landowner compliance (will the National Trust and Wildlife Trusts for example sign-up? I have a badger main sett on my own land in Gloucestershire and I can assure you no culling will ever take place there!).
Furthermore, it is necessary to consider the environmental impacts of culling (will there be more foxes and fewer hares, for example, as a result of badger removal?), it is in this context that to proceed with culling would also run directly counter to the UK Government’s “Shared sustainability principles”, one of which is to “use sound science responsibly”. In detail, this principle explains that the Government is committed to “ensure that policy is developed and implemented on the basis of strong scientific evidence, whilst taking into account scientific uncertainty (through the Precautionary Principle) as well as public attitudes and values”. How the Government would be seen to be adhering to this principle and yet ignore the ISG’s conclusions is beyond me. Finally seeking to implement a culling policy would generate inevitable, overwhelming opposition from the public to one of Britain’s most loved indigenous creatures being eradicated from whole areas without good scientific reason. It would undoubtedly be hugely unpopular.
Surely the Government will not set the clock back 30 years and resume badger culling, merely, it seems, to appease farmers? To be seen to be doing something, even though this could actually make the problem worse. There is a research project funded by DEFRA to develop a badger vaccine, and sound advice on improved farm husbandry and biosecurity is emerging from on-going research, giving realistic long-term prospects for dealing with the risk of infection of cattle by badgers. As we proceed towards that goal, and hopefully crack down hard on the cattle side of the problem, the case for any further badger culling is non-existent.
Warren Cresswell
12th November 2007
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M. Jack M.P.
Chairman, the Select Committee on the Environment
The 1997 Krebs Report concluded that, despite 15 or more years of badger culling in Great Britain, it was still uncertain whether this was effective because no proper scientific experiment had been conducted. As a result, the government, in the form then of MAFF (now DEFRA ) commissioned an extensive, rigorous 10 year experiment ( the RBCT – the Random Badger Culling Trial). Ten triplets, each one containing a control area ( no culling), a proactive area ( culling as many badgers as possible) and a reactive area ( culling badgers only in response to cases of TB in cattle local to the badger setts), each of roughly 100 km2, were investigated over a rolling 5 year period between 1998 and 2004. Professional trappers were employed to survey each area, set cage traps and kill the badgers. A team of research scientists, the ISG (Independent Science Group), including ecologists, veterinarians and statisticians, oversaw the project, independent of the team actually carrying out the project. Their work has been published as the experiment has proceeded to completion, in an important series of highly rated scientific papers, peer-reviewed and published in leading journals. They demonstrate very clearly how many badgers were killed, how many cases of tuberculosis there were in badgers and cattle in those areas, how many badgers were culled in all three sorts of area ( control, reactive, proactive). They also investigated the efficiency of the programme, in the terms of culling badgers, reducing cases in cattle and the costs of achieving that reduction. They reach the very clear conclusion that badger culling cannot meaningfully contribute to the long-term control of bovine TB in Britain. Sir David King, as Chief Scientist, has reached a different conclusion, on the basis of the same evidence, and claims to offer the Government better, different, scientific advice on how it should be done.
The Mammal Society comprises a free assembly of members, amateur and professional, whose interests cover the full range of academic and practical mammalogy. Many are ecologists, but that encompass a full range from conservationists at one end to pest controllers at the other. We are anxious, as a Society, to see the fullest possible range of British mammals thriving in the country, but are not in principle opposed to culling where it can be shown to be effective ( for example mink on Lewis to protect ground-nesting birds, or elsewhere to protect water voles). We boast that we try to offer the best scientific advice in contentious cases. Clearly, what we have in the case of badgers, bovine TB and culling is a conflict of scientific advice. In these circumstances, we clearly should offer our advice.
At the heart of Sir David’s case is his contention that thinning out the number of badgers would reduce the chances of them passing TB to cattle. Yes, of course. The intention of the RBCT was to find out by how much, Sir David himself quotes the answer: averaged over a ten trial areas, and at the heart of the proactive control areas, about 30%. Put another way, he advocates a substantial cull of badgers in order to achieve, if he is lucky, only 30% reduction of the cases of TB in cattle. So how is it proposed that the other 70% of the cases, the considerable majority, be controlled?
He is himself aware in part of the other major contribution to new cases of TB in cattle – cattle movements. Referring to the important paper in Nature on this topic, ( Gilbert et. Al. 2006), he acknowledges that new cases of TB in cattle at a long distance from the known hot spots in SW Britain are probably the consequence of livestock transport. He then makes the extraordinary assertion that the other main pattern of increase in cattle TB cases, the expansion in intensity and extent of cases around those hot spots, is entirely due to badgers. Has he evidence that there are no local movements of cattle contributing to these increases ? He must be aware that with TB in Ireland, as indeed during the recent and earlier foot and mouth outbreaks, farms that occupy multiple sites ( split holdings ) are considered a major risk. He also seems to be unaware, certainly fails to acknowledge, that the routine TB testing of cattle is not 100% reliable. About 5% of cattle which test negative are actually carrying TB and therefore, since they are not culled, survive to re-infect the herd or reveal themselves as positive, at a later date. ( The converse also applies; some cattle that test positive, and are culled, turn out on post mortem not to be infected). Clearly, this unreliability, combined with local and more distant cattle movements, has a part to play in maintaining and spreading TB in cattle. How much was not part of the subject of the RBCT, nor the ISG’s remit. Clearly, controlling these movements must play a large role in controlling the incidence of TB in cattle. There must be a suspicion that extra movements following BSE and foot-and-mouth as farms restocked played a large part in precipitating the recent upsurge, but we acknowledge that this is speculation, not scientific fact.
Sit David speculates that is the areas of badger control were expanded to perhaps 300 km2, culling might be more efficient, because peripheral area, where cases of TB in cattle apparently increased in reaction to badger culling ( the accepted perturbation effect ) would be proportionately smaller. He provides absolutely no evidence that this would in fact be possible or practicable. If the trapping were to be less effective, because it would be spread more thinly over a larger area, its effectiveness would be much reduced. Sir David has no more evidence for his case than we would have for this last speculation. There is simply none available. Whistling in the dark is a poor basis for offering the government scientific advice.
This argument highlights the weakest point of Sir David’s report. He says that he will not discuss the economic basis of his proposed advice. That is to ignore a major segment, and a critical one, of the I.S.G.’s report. Just as was found by the Dunnet report over 20 years ago, the economics of culling badgers makes no sense. It would cost far more to cull each badger that the value of any cattle saved. Even more economically efficient methods of culling badgers ( a return to , for instance, to gassing ) are not thought likely to overturn the economic arguments, and certainly Sir David does not address this aspect at all.
Sir David’s report was also extremely weak in considering the practicality of any proposed cull. Again, the RBCT provided much relevant information, though he appears not to acknowledge its relevance. He is dismissive of some of this, reporting that the reduction of badgers in the proactive areas was only was only determined by indirect evidence ( signs; presumably he meant rates of occupation of setts). In fact, the densities of badgers in culled and controlled areas were compared by using road transects at night, and the numbers culled precisely. They were used to estimate trapping efficiency by comparing the numbers trapped on the first occasion with those trapped in total over the five years of culling in each triplet. For 7 out of the 10 trials, proactive culling removed about 70% of the badgers present. However, in 3 of the trials, the trapping was left effective, around 30 - 35%. Why? In some cases because trapping in winter was less effective than trapping when badgers are more active, but in one, at least, because if interference from people opposed to the culling programme. This possibility is not even mentioned.
One might have expected dispassionate scientific advice to draw on evidence from elsewhere. Sir David acknowledges that the Irish 4 areas trial also demonstrate some reduction in the incidence of TB in cattle in four areas where badgers have been culled ( more severely than in Great Britain, and using snares which we would consider illegal). He does not quote their scientific team’s conclusion that badger culling has no worthwhile long-term role to play in the control of the disease in cattle. Nor does he draw on the experience of Northern Ireland, where no culling has taken place, but where TB in cattle is if anything under rather better control than in Great Britain.
In short, there seems to the Mammal Society to be no serious comparison in the value of the scientific advice offered, on the one hand by the ISG, and on the other, by Sir David King. He adduces few serious arguments, no evidence, no improved analysis, that in any way casts serious doubts on the conclusions reached by the ISG. Unless he can do this, his weak advice should be ignored.
Yours sincerely,
D.W. Yalden, President, The Mammal Society
c.c. Rt. Hon. Hilary Benn, Secretary of State for the Environment. Food and Rural Affairs.
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The badger extermination or culling programme under consideration by the UK Government has no scientific justification, but is the result of relentless pressure from lobbying groups from the farming industry.
The Government is considering licensed and targeted culling of badgers despite the research findings of the Government-appointed Independent Scientific Group on Cattle (ISG). A scientific experiment undertaken by the ISG has shown that badger culling actually increases Bovine TB in cattle. Licensing farmers to remove badgers will result in erratic and sporadic killing of badgers.
It is not possible to determine whether a badger is infected with Bovine TB by visual examination, or whether a sett is inhabited by infected badgers. Therefore existing plans put forward by the National Farmers' Union (NFU) for killing by lethal gas will inevitably lead to the death of thousands of healthy badgers and other non target species such as rabbits, polecats, foxes and even otters.
One option the Government is proposing is for individuals to be able to kill the badgers on their own land. This could lead to thousands of healthy wildlife being subjected to cruelty. Without laboratory testing it is impossible to tell whether a badger is Bovine TB positive. Bacteria found in latrines outside setts do not relate to infected animals underground. Yet, all too often farmers claim they 'know' which badgers or setts are infected with TB.
It will be impossible to identify who holds licenses for culling. The protection of the badger species will collapse and persecution by digging and baiting will return.
Not all farmers wish to gas. snare or shoot badgers on their land and would probably invite others to carry out these tasks. This would open the door for diggers and baiters that, even now, carry out illegal activities involving great cruelty and suffering as a result of stabbing, shooting of badgers or baiting with dogs. |
Badgers. who have been persecuted for many years are now protected by law in the British Isles. Yet large scale, blanket killing being considered would lead to local extinction of badgers, contrary to the provisions of the Bern Convention, which Britain has signed.
Following the Kreb's Report, the Randomised Badger Culling Trial (RCBT) was implemented in 1998 to evaluate different ways of culling badgers to see their effect on TB outbreaks. Ten sets of three test areas each measuring 100 km sq (triplets) were selected as part of an experimental trial to research the effect of different treatments. Each triplet set contained an area where badgers were left alone (No Cull), an area where badgers were killed only once an outbreak of TB in cattle had been detected (Re-active Cull), and an area whereas many badgers as possible were killed (Proactive Cull).
Research has shown that badger culling is not an effective TB control measure unless badgers are exterminated from areas that exceed 300 squared kilometres. This is equal to twice the size of Greater London or 50. 000 football pitches. A mass slaughter of this magnitude is neither practical nor cost effective andwould be unethical and unsustainable.
Badgers have been implicated in the spread of Bovine TB for the past 25 years. Despite badger culls on land where Bovine TB outbreaks have occurred - known as re-active culling - the incidence of Bovine TB has increased dramatically.
Scientific research has shown that this results in a 27% increase in cattle breakdowns (cattle diagnosed with Bovine TB). This is caused by disturbance within the badger population, manifest as increased movement and contact between individual badgers that have not been caught.
Pro-active culling creates a 20% reduction in cattle breakdowns in the areas where culling is carried out. However, badger movement on the perimeter of the culling areas increases the incidence of Bovine TB by 30%, thus exacerbating the disease problem considerably in the long term. Even with a 20% reduction in TB breakdowns in culling areas attributed to badger transmission, there still remains 80% transmission predominately attributed to cattle to cattle infection.
The third option of eradicating badgers over larger areas would be unworkable as it is impossible to gain access to more than 70% of land due to refusal of admission - who is going to go into school playing fields, private gardens and nature reserves to kill the badgers? Even if it were possible, over a long period of time, to exterminate all badgers from an area, it would eventually be repopulated. If immigrants are very susceptible to Bovine TB, disease outbreaks would increase dramatically. Furthermore, Bovine TB is also evident in other wildlife species, such as deer, foxes, rats and moles.
We appreciate that the farming industry is experiencing a very serious problem. However, wasting even more money to satisfy the demands of a minority seemingly determined to ignore scientific facts is not a viable solution. Millions of pounds have already been spent on badger culls. It is time to put funding towards research that will deliver lasting benefits, namely the development of a cattle vaccine, movement controls and support for farmers, who may incur additional costs through stricter safeguards.
Indiscriminate wholesale killing of badgers across large areas will also bring death to many healthy individuals. Those with natural immunity will also be removed from the population, rendering it more vulnerable.
Furthermore, the methods used to kill badgers over large areas can cause immense suffering and are therefore inhumane. They include snaring, shooting and gassing. Gassing was discontinued in 1982 by the Government when it was found to be inhumane as it is impossible to get lethal concentrations of gas into all parts of the sett leaving animals only partially poisoned and suffering. Gassing will also affect other species, as it is impossible to tell which animals are in a sett at a given time. Rabbits, foxes, polecats and even otters could all become innocent victims of a poison gas campaign.
Professor Bourne. Chairman of the ISG. has publicly stated that the Government's consultation paper contains inaccuracies in important respects. In particular. the ISG say. "there is solid scientific evidence that two of the culling strategies proposed will increase rather than decrease cattle breakdown rates and the consultation paper fails to make this finding clear. " |
Cattle to cattle transmission is the main route of infection for Bovine TB. As a matter of priority, measure sto address this primary disease risk must therefore be taken before a blanket kill of badgers should even be considered.
The remaining 80% of TB outbreaks is attributed mainly to cattle to cattle infection.
In line with other countries that attended the 4th International Conference on Mycobacterium Bovis in Ireland in August 2005 we should therefore:
