Bovine TB: Fact, Fantasy & Politics

Bovine TB

  • Author: Badgergate
  • Published: 07-02-2013 at 12:15:50

"Bovine TB is the most pressing animal health problem in the UK."

Owen Paterson, Oxford Farming Conference, January 2013
Bovine tuberculosis or bovine TB (bTB) is an infectious disease of cattle caused by Mycobacterium bovis, which can also infect a wide range of other mammals including humans. The threat to human beings from bTB became negligible after the advent of routine pasteurisation of milk and is now a relatively rare occurrence in developed countries.  Bovine TB is considered a low public health risk in the UK. The closely related Mycobacterium tuberculosis causes most TB in humans.

The management of bovine TB in the UK has a long and convoluted history. Bovine TB was a major problem in the UK cattle population in the 1930s. It was brought under control successfully through the introduction of a nationwide TB eradication scheme in the 1950s that involved strict cattle movement controls and compulsory testing and removal of all reactors, sometimes resulting in the removal of entire herds. The incidence of bovine TB fell steadily throughout the 1960s and reached an all-time national low in the late 1970s and early 1980s, although there were still some areas, for example, in the Southwest of England and the Southwest of Wales, where the incidence of bTB remained higher than the national average. In the Southwest of England, TB incidence in cattle herds is reported to have remained three times higher than in the rest of Great Britain. (Defra 2010, Annex A, Para 15).

The discovery of a dead badger infected with TB on a cattle farm in Gloucestershire in 1971 ignited the debate about the role of badgers in transmitting bovine TB to cattle and being a ‘wildlife reservoir’ of the disease. This in turn led to the first official badger culling programmes in Britain, which initially involved gassing of badger setts. When scientific experiments revealed that gassing did not result in a quick and relatively painless death, culling methods were replaced with trapping and shooting. Periodic policy reviews were conducted and new approaches tried until an independent review of bovine TB management policy in 1996, chaired by Professor (now Lord) John Krebs, recommended that the Government undertake a proper scientific trial to establish whether badgers were indeed responsible for the spread of bovine TB in cattle and whether culling badgers was actually helping to reduce the incidence of TB in cattle.

And so the Randomised Badger Culling Trial (RBCT) came into being. Conducted over nine years from 1998 to 2007 at a cost of nearly £50 million pounds, this was the longest and most expensive experimental study of the effects of badger culling on TB incidence in cattle in the world. The RBCT remains the gold standard of research on the effects of badger culling on bovine TB incidence in badgers and cattle and is acknowledged to provide “the best scientific evidence available from which to predict the effects of a future culling policy.” (Defra 2011, Para 3).

The overriding conclusions of the Independent Scientific Group (ISG) on Cattle TB that was set up to conduct the RBCT were simple and to the point:

“Our overall conclusion is that after careful consideration of all the RBCT and other data presented in this report, including an economic assessment, that badger culling cannot meaningfully contribute to the control of cattle TB in Britain.

We further conclude from the scientific evidence available, that the rigorous application of heightened control measures directly targeting cattle will reverse the year- on-year increase in the incidence of cattle TB and halt the geographical spread of the disease.” 

(ISG 2007, Paras 10.92 & 10.93, respectively)

One would have thought that after nine years research, 50 million pounds of taxpayers’ money and some 11,000 dead badgers that would have been the end of all further discussions on badger control as a strategy for bovine TB management in Britain. But sadly not.

Government data suggest that bovine TB incidence in cattle herds in England is continuing to rise slowly, although some of these data are difficult to interpret because of the manner in which they are collected and reported. The reasons for the apparent on-going spread and increasing incidence of bovine TB are also hotly disputed; some even question whether this rising trend in the incidence of bTB is actually the result of more rigorous cattle testing and better diagnosis, which means more TB cases are being detected in recent years, compared to earlier years. Furthermore, in 2001, during the nation-wide epidemic of foot-and-mouth disease (FMD), the majority of routine cattle testing for TB was suspended (ISG 2007, Para 4.45).

While the Welsh Assembly Government finally opted for a badger vaccination programme and other cattle-based measures for bovine TB eradication, in England, the Coalition Government has concluded that it will not be possible to eliminate TB in cattle without also addressing the disease in badgers as it is argued that the badgers will simply re-infect the cattle (Bovine TB Eradication Programme for England Section 3.3, p.42,  Para 96). This seems to be directly at odds with the main conclusion of the ISG report on the RBCT.

So who is right? What is the fresh evidence that has come to light since the RBCT that has persuaded the Government to decide that badger culling can after all contribute meaningfully to bovine TB control in England?

In this section of Badgergate, we look at the evidence cited by the Government to support badger culling as well as other facts and figures about bovine TB and its management, including the key areas of disagreement over the usefulness of badger culling as a ‘tool’ for bTB control. We also review past and present policies on bTB management and provide some background on the key players involved in designing and implementing these policies. While our focus is on the current badger cull policy and the pilot culls that are to be implemented in West Gloucestershire and West Somerset in the summer of 2013, we believe that an understanding of history can help us better understand not only the present situation, but also contribute to making more informed choices.

This is perhaps the most complex and time-consuming area of Badgergate's work. We have a lot of information at various stages of preparation that we will upload periodically.