Tuberculosis (TB) is a disease which, in its various forms, can infect a wide variety of animal species. The most important “human” form of TB affects people in very poor areas of the world (such as parts of Africa and elsewhere), affecting people live in very poor living conditions or those with compromised immune systems. Financially, the most damaging form for farmers and taxpayers is “cattle” or bovine TB (bTB), as this affects dairy and beef cattle, and other species – very occasionally humans. Although there is a small risk of infection, bTB does not pass into the food chain because milk from cows is pasteurised to kill any bugs and meat is inspected at the slaughterhouse. The vast majority of the few people diagnosed with btb each year have caught it from drinking unpasteurised milk as a child.
Minimizing the Risks
To minimise he risk of bTB transferring into the human food chain, and to reduce the risk of it spreading to other animals, DEFRA have a testing program for cattle. In the past, DEFRA and farmers organisations believed that a very limited cattle testing regime was good enough to locate infected cattle, so they could be slaughtered before they could spread the disease. However, most cattle were never tested in their lifetimes, and this meant that bTB could spread around as cattle were moved through livestock markets and into different areas of the countryside. The horrors of the Foot and Mouth disease in 2001 made the bTB situation much worse – this was because all the cattle were killed in huge areas of the countryside, meaning that those areas had to be re-stocked with cattle bought in from outside the area. This often meant that areas which were “clean” from bTB, became infected as infected cattle were shipped in in large numbers.
This cattle testing scheme has come under criticism as the skin test used is estimated to be only between 60-80% accurate. For more information on this and badger culling see the following blog articles;
Recently it was discovered that infection with liver fluke can mask a bTB infection during testing, potentially affecting up to a third of cattle tests.
Other ways in which the likelihood of a bTB infection can be reduced is to adopt better farming practices. These recommendations usually involve maintaining good land-management practices (such as thick hedgerows and fresh running water supplies for animals); as well as using fencing to keep cattle separated from other farms and from wildlife species. Studies on farm practices with regard to conservation and improving herd access to trace elements in their diet seems to suggest that such cattle do not succumb to bTB infections as easily. It has also been found that certain breeds are more susceptible to the disease.
Studies have also shown that it is possible to keep badgers out of farm buildings and feed stores. This is extremely effective if done properly.
The disease can also pass from cattle into other common species, such as cats, rats, deer, badgers, earthworms and others. It is believed that bTB passes from cattle to wildlife species when wildlife forage on pastures recently grazed by infected livestock. The bTB infection may be present in body tissue and fluids from infected cattle – this including saliva/sputum, milk, urine and excrement. It is likely that badgers become infected from infected cattle, because badgers use their noses to flip over infected cowpats to get to the earthworms which live underneath; or because they eat earthworms which get infected by passing through the cow pats.
DEFRA and NFU
DEFRA and the NFU state that infected badgers represent a significant source of re-infection to cattle in some areas. However it is not clear what percentage of the infection level is due to wildlife and scientific estimates vary widely.
DEFRA (and previously MAFF) used cyanide gas to exterminate badgers on infected farms, but it was discovered that it was ineffective and caused unnecessary suffering.
The badger is a protected species due to persecution (badger baiting) and it is illegal to harm, kill or capture them without a licence. However, DEFRA undertook a “controlled” badger culling program (known as the Krebs trial) of badgers to control bTB on farms in designated parts of the country. It took 10 years and killed over 11,000 badgers, at a cost of approximately £50 million.
What Krebs trial found was that killing badgers appears to provide a very slight reduction in cattle TB where badgers are killed, but just outside the killing zones, the amount of TB goes up; cancelling out the beneficial effect. The Krebs experiment suggests that badgers at least 70% of badgers would have to be killed across large areas of Cornwall, Devon, Dorset, Somerset, Avon, Gloucestershire and the Midlands to have a significant positive effect. In addition, the only ‘safe’ and humane way to do this is to follow very closely the methods used in the original trial.
Importantly, the reduction in bTB in cattle would be far less than if cattle testing measures were improved. The government believes they can achieve a reduction in the new incidence of herd breakdowns of 16% using a different culling method which is untested, but even if it works, this would leave 84% of the problem still there. Many wildlife groups and experts are extremely concerned about the humaneness of the new method (free shooting at night).
Badger groups, many scientists and other conservation and wildlife groups believe that the solution to bTB infections in cattle is predominantly in improved cattle testing, better animal husbandry, fewer cattle movements, having closed cattle herds (where potentially infected cattle are not brought in or allowed to visit for breeding purposes) and eventually vaccination of both badgers (now possible and carried out in 2011 by Gloucestershire Wildlife Trust) and cattle. Vaccination of cattle is not allowed under EU rules, but our government is slow to push for a change, even though a vaccine and associated test is close to being a reality.
Importantly, we are not aware that any badger has tested positive for tb in Lancashire.
For more information
Please see our press release section for updates and information on the cull. The Badger Trust is challenging the legality of the decision (taken by Caroline Spelman) to cull badgers. The Judicial Review will be held on 25th and 26th June 2012.
Other useful links: