Bad Science

Introduction- The major reason for the Government’s failure to control bovine tuberculosis (bTB) has been the focus on badger culling at the expense of taking a more holistic approach to the management of cattle health. The culling of badgers to control bTB has been going on since the 1970s when a dead badger was found to be infected with the disease. Over the last 33 years thousands of badgers have been killed, whilst the spread of bTB has continued to spiral out of control. There has been a small amount of evidence that badgers may play some part in the spread, but the extent of their involvement has not become clear. Badgers are just one of many species of wildlife known to be a carrier of the disease, yet they appear to have become the main focus of efforts to control it.


Successive Governments have commissioned ‘independent scientific reviews’ of the bTB problem (Zuckerman, 1980; Dunnet et al, 1986; Krebs et al 1997; King 2007). However, the terms of reference have forced the reviews to focus on badgers at the expense of addressing more likely causes. Meanwhile, the only other recognised control strategy for TB has been the largely inadequate cattle testing programme. Cattle testing has, at best been sporadic, and many herds have avoided testing altogether. The test itself is frequently inaccurate in that around 5% of infected cattle are not detected. Similarly, cattle tested positive are often later found, upon post mortem, not to be suffering from the disease at all.


In 1997, after an independent review by Sir John Krebs, one of the largest field experiments ever undertaken was designed and implemented. Over the next decade, at a cost of £35 million, the Randomised Badger Culling Trial (RBCT) was carried out under direction of the Independent Scientific Group on Cattle TB (ISG), chaired by Professor John Bourne. The RBCT consisted of 10 trial areas in the UK, chosen for their high levels of bTB. Each trial area consisted of two cull zones (a proactive and a reactive) and a control (or no cull) zone. In the proactive areas the aim was to wipe out as much of the badger population as possible over an area of approximately 100km2. In reactive areas, of approximately the same size, badgers were culled only around farms where bTB outbreaks had occurred.


During the trial DEFRA operatives trapped and shot around 11,000 badgers, orphaning hundreds more which would have starved to death, underground and uncounted. The results from the different trial areas were mixed, in some areas bTB incidences increased; in other areas there was a reduction in the number of outbreaks. Midway though the experiment, the dramatic decision was made to halt the reactive culling with immediate effect after interim results showed an overall increase of 27% in bTB in these areas.


After 10 years of killing, the ISG published its findings in ‘Bovine TB: The Scientific Evidence’. This report concluded that “after careful consideration of all the RBCT 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.” (ISG Final Report, June 2007)


Although there were decreases in disease outbreaks in the centres of some of the proactive culling areas, the culling itself was responsible for the disruption of badgers’ normally stable social groups, leading to increased movement in the remaining badgers and causing them to come into contact with badger and cattle populations they may not otherwise have had contact with. It is suggested that this ‘perturbation effect’ may have been responsible for increased outbreaks in surrounding areas. This argument has since been given more weight with the discovery that infected badgers may move around more than uninfected badgers and it further emphasises why culling cannot be used as an effective control measure. It also shows that DEFRA (and formally MAFF) have almost certainly exacerbated the situation through various programmes of badger extermination during the years leading up to the RBCT.


Instead the ISG listed a number of cattle-based control measures that it believed would be effective in reducing the number of infections, these included more thorough controls on cattle movements, strategic use of the gamma interferon blood test in routine and pre-movement testing, more frequent routine testing of herds, quarantine of purchased cattle and whole herd slaughter for chronically infected herds. The ISG report highlighted the weaknesses in existing testing regimes and the significant contribution of cattle-to-cattle transmission in all areas where TB occurs, acknowledging it to be the main source of infection in some areas. The ISG even went as far as to say “scientific findings indicate that the rising incidence of disease can be reversed, and geographical spread contained, by the rigid application of cattle-based control measures alone.”


Unsurprisingly the results of this latest 10 year study have come under criticism from the farming community and other groups and individuals determined to scapegoat badgers in the battle against TB. It has been claimed the trial was scientifically compromised, yet the ISG stand firm in their methods and have made assurances that the trial design, surveying, data collection and analysis and many other aspects of their work were subject to continual independent audit. Additionally, the findings of the trial underwent rigorous peer review prior to publication in highly regarded, international scientific journals.


In October 2007, Sir David King, the Government’s Chief Scientific Advisor at the time, produced his own report on the TB situation, entitled “Bovine Tuberculosis in Cattle and Badgers”. This report, which was not subject to peer review and did not get published in the scientific literature, claimed to have used the data from the RBCT and the ISG report, yet came out with a significantly different set of recommendations. King’s conclusions greatly inflated the potential contribution of badger culling, recommending the removal of badgers over vast areas contained within hard geographical boundaries such as rivers or motorways. He also failed to recognise the major problems surrounding cattle testing, and made no consideration of the practicalities or costs of culling, deemed by the ISG to make a large scale badger cull unfeasible. His work was heavily criticised as being ‘unbalanced’, ‘inexpert’, ‘superficial’, ‘selective’ and ‘pervaded by errors’ by a number of leading scientists and national organisations.


One final concern, which has been given little consideration throughout the RBCT, is the possible impact of a large scale badger cull on the wider environment and particularly in relation to other wildlife species. DEFRA refused to carry out an independent environmental impact study before commencing the trial and pressed on regardless. A cull of this size and nature would directly counter the Government’s “shared sustainability principles”, one of which is to “use sound science responsibly” by ensuring “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”.