Tuberculosis is a disease which affects the lungs and causes breathing problems and general deterioration in health of an animal. Importantly, there are several forms of tuberculosis (TB), which can affect different animals to varying degrees.
Humans can get one form of TB (extremely rare unless you come into contact with another human with TB - usually in a third-world type country). TB in humans usually causes serious breathing difficulties; and is usually treated with powerful special anti-biotics. However, because of the general over-use of anti-biotics, some human forms of TB are now becoming resistant to some anti-biotics, with the expectation that in a number of years time, some human TB may become untreatable unless new anti-biotics (or other treatment) have been researched and developed.
Cattle can also suffer with TB (the form they get is known as Bovine TB or bTB). Cattle with TB can prove very infectious to other cattle (and certain other farm animals and wildlife species), with the result that the entire herd on a farm can be killed to try and eradicate the problem. However, the current "skin test" for TB is not reliable, and cows are often not tested very often or when they are sold or transported. The skin test gives rise to errors such as false-positives and false negatives:
Accordingly, it seems likely that some cows with undiagnosed TB will be moved from one farm to another passing on their infection as they go. The problem may then not be spotted until too late.
Many other animals can also get other forms of TB. Examples of these other animals include rats, mice, water voles, deer, domestic cats and dogs, pigs and wild boar, sheep, goats, ferrets, alpacas, llamas, foxes, badgers, etc. The risk here is that if cattle are pumping TB into wildlife species, there is a chance that this will adversely affect those species. If the problem gets serious enough in wildlife, it can be called a wildlife reservoir, where the TB infection can them be spread around other species and back into cattle.
Relatively little scientific research has been done on these risks, although Defra publish statistics of infected cattle numbers periodically. The essence of the problem though is that the overwhelming majority of the TB infections in animal species originate in the cattle populations; who spread it outwards. Whether we have reached the point that TB is self-sustaining in species other than cattle is not known with certainty. However, it is clear that if it is possible to solve the TB problem in cattle; the seriousness of TB infections in other species becomes of decreasing concern because you would no longer have this huge reservoir of farm-based infection infecting many other species.
In the wild, of course, some badgers are infected with TB, particularly in the south west of England, and west Wales. As at November 2000, these animals were the subject of a control experiment by the DEFRA. In this experiment (known as the Krebs experiment), large areas of countryside were marked out on a map. In some areas all badgers are killed, in other no badgers are killed and in other areas just those badgers where TB has occurred in cattle. This experiment was being done by the DEFRA, but the experiment was less than perfect due to outside interference by people other than DEFRA. Some farmers believe that as badgers can get TB, killing all badgers will remove TB from cattle; and they try to kill badgers, even in areas where they shouldn't. Some animal rights activists believe that no-one has the right to kill badgers (and especially not for the "political purposes" of keeping a few disgruntled farmers happy). These activists do all they can to disrupt the killing of badgers by DEFRA (this includes asking landowners not to allow DEFRA staff and contractors on their land, destroying traps set by DEFRA, and doing what they can to save badgers from being killed).
According to DEFRA, the Krebs experiment should have provided a definitive answer as to whether badgers give TB to cattle or not. However, many independent experts believe that the whole Krebs experiment has a number of scientific flaws and has not yielded results that all people agree on.
The numbers published by Krebs trial showed that killing badgers reduced bTB in cattle where the badgers were killed, but that it increased bTB in those areas outside the badger killing zones. It also strongly suggested that the action of killing badgers cause enormous disruption to badger society; and it is this disruption which makes things worse. The Krebs trial provided no proof that badgers and cattle infected one another with the bTB infection; and was silent on whether the numbers were a genuine causal link or simply a manifestation of the numbers; where very very few badgers were found to be infected with bTB.
Irrespective what the Krebs trial results purport to show; it is unlikely that such results would be accepted by ALL sides of the debating chamber.
No matter what the Krebs report points towards, there is a continuing debate about the role of badgers infecting cattle with TB - basically it is still unknown whether badgers give TB to cattle, or cattle give TB to badgers, or whether they give TB to each other.
However, there is a strong belief that it is actually very difficult for a badger to pass TB to a cow - even in the most extreme circumstances of close and intimate living. For a report on some research into close-living TB-positive badgers and TB-negative cows, read the article in the following link:
Some respectable scientists believe that cattle must meet several conditions before they can catch TB. The argument goes that rather than getting TB immediately they are first exposed to the TB bacteria, the cattle must have most of the following conditions: climate history, certain vitamin deficiencies, compromised immune system, intensive living conditions, high-stress lifestyle, lack of natural immunity to infection and disease, and multiple-exposure to the TB bacteria in a short space of time. In other words, cattle which are raised in natural field-based conditions, with minimum use of anti-biotics and other drugs, low-stress organics lifestyle are much less likely to succumb to TB infection. In organic terms, the higher incidence TB in cattle in the south-west of England is more likely to be due to more intensive cattle-rearing and animal husbandry, than the presence or otherwise of TB-infected badgers.
Another aspect is that TB can be passed from one individual to another by contact with infected breaths, coughs or sneezes, or infected urine or faeces. A very good place for badgers to catch earthworms and dung beetles, is in cow-pats. Perhaps, the argument goes, it is the cows who have TB, who pass it to badgers when the badgers snuffle through cow-pats looking for worms and beetles.
In financial terms, the problem with TB is an expensive one. Cattle found with TB, can cause the whole herd to be killed, and the government having to pay partial compensation to a distressed farmer. DEFRA seem content to conduct the Krebs experiment (to prove that badgers give TB to cattle - if true), and continue to pay out large sums of public money to farmers. However, precious little monies have been spent developing an accurate and reliable test for TB in cattle; or some sort of vaccination for cattle or other animals.
There is not any definitive scientific guidance as to whether badgers give TB to cattle or vice versa, there is a great deal of "politicking"; where one sides criticises the other side and no-one is very much the wiser.
In our view, DEFRA would be better spending the British public's money on better diagnostic tests in cattle and other animals, investigating vaccines for TB for cattle and other animals, and conducting small-scale laboratory experiments in controlled conditions to assess TB transmission between cattle and all other animals (such as rats, mice, deer, cats, foxes, badgers, etc).
Martin Hancox has been involved in expert committees for many years representing the case of the badger in the debate. In The Great Badgers and Bovine TB debate in the Biologist Journal (1995) volume 42 number 4 pages 159 to 161 he gives a summary of the situation, pointing out that research has not yet been implemented to determine whether badgers give tuberculosis to cattle or vice versa.
A lot has been written concerning this issue. If you want to look further into this debate, Nolan and Wilesmith have written a useful review Tuberculosis in Badgers (Meles meles) in the Journal of Veterinary Microbiology (1994) volume 40 number 1-2 pages 179 to 191.
Also, please look at the Tuberculosis section of our web site.
Badgerland are here to promote the protection of badgers (and other animal species) using the science as a solid basis on which to develop policy and proceed. The Krebs trial provided enough ammunition for us to be convinced that the culling of badgers will never make a meaningful contribution to the reduction of bTB in cattle. The skin-test (for bTB in cattle) is too unreliable to be justified in the modern world - especially in association with valuable herds, valuable animals as well as rare breeds and breeding lines which are genetically valuable.
There is now ample evidence that the use of a bTB vaccine would allow the bTB situation to be managed better, at lower cost and in a far more humane manner than repated rounds of killing animals.