Welcome to a website that poses difficult questions about current policy regarding Bovine TB and the impact that TB testing has on the farming and wider community.
On this website we consider current Bovine TB policy in England and Wales and its impact on the farming community. We then go on to propose alternative, more cost-effective and acceptable approaches to tackling the disease that would gain better support from the farming community and the wider society.
We have drawn our evidence from a variety of sources, but in particular from Defra (the Department for Environment Food and Rural Affairs) and from earlier work by Professor Paul Torgerson(1) and Professor David Torgerson (2) and from working farmers.
Where numerical or statistical arguments are necessary to show what is actually happening on farms, we have explained the argument as clearly as possible. We have also explained that some widely held views are supported only by statistical correlation (open to many alternative explanations), rather than any evidence of a physical link between effect and presumed cause.
1. Professor David Torgerson, Department of Health Sciences, University of York, England.
2: Professor Paul Torgerson, MRCVS. Division of Epidemiology, Vetsuisse Faculty, Univer-
sity of Zurich, Switzerland
We summarise the present situation in brief below:
- Health Concerns
- Current UK Policy
- What is the Solution?
In the UK, human infection with the bacterium responsible for Bovine TB, Mycobacterium bovis, is almost non-existent, principally because of the almost universal pasteurisation of milk and the cooking of meat. Most of the very few cases that have been recorded were, in fact, initially contracted in other countries or before the pasteurisation of milk became the norm.
Infected cattle have little probability of developing the disease and seldom show symptoms during their short economic lives. The principal animal welfare implication in all this is not the disease itself but the premature slaughter of healthy animals under the current ‘test and cull’ policy. The effect of the policy is worse than the disease.
The above chart was taken from a website about 'Thermal Processing Pasteurisation'
Defra’s stated reasons for the current policy, principally protection of human health, exports and animal welfare, do not stand examination.
The policy relies on a flawed diagnostic test that even Defra describes as ‘imperfect’. It leaves potentially infected animals in the herd, and falsely condemns large numbers of healthy animals.
The policy is causing widespread losses and distress to farmers, and is a burden on the taxpayer. After 60 years of cattle testing and culling, further decades of compulsory slaughter separate us from an uncertain chance of TB free status. Defra admits the policy is failing and that the reasons are not known.
According to Defra cattle vaccination will be licensed in 2012. Only the EU prevents us from using vaccination and from allowing farmers the freedom to choose the most suitable means of Bovine TB control for their circumstances. Cattle vaccination is a priority.
DEFRA confirms “BCG has been used in numerous vaccine studies since 1911 in cattle. Although studies are sometimes difficult to compare - as a variety of vaccine strains, challenge strains, vaccination and infection routes, and ways to measure protection have been applied - the results of the majority of these studies have demonstrated considerable protection. The results of controlled field studies are more variable but the overall majority also demonstrated protection, including recent studies conducted in Mexico (Lopez-Valencia et al., 2010) and Ethiopia (Ameni et al.,
For an update of the current DEFRA position regarding vaccination click here.
This discussions on this website will hopefully outline some solutions.
If you want to view or print the full Rethink Bovine TB discussion document then go straight here
Have your say on TB Eradication in England. Complete this questionaire today.
How current policy is delivered
Under the current UK ‘test and cull’ policy, cattle are tested at intervals determined by risk of infection. Those that fail the test are slaughtered and severe restrictions on cattle movement are placed on the farm. The farmer has no input to this procedure other than being forced to present their animals for testing when told. If a farmer has any objections to the procedure or the application of the test then he is threatened with withdrawal of farm support funding. Some farmers currently disagree with the current test and the way it is carried out.
In this test, a small amount of tuberculin (a sterile extract obtained from a culture of M. bovis) is injected into the animal. A swelling will occur if the animal has previously been challenged by, and the immune system has reacted to, tuberculosis bacteria. However, reactions of the animal’s immune system to other types of mycobacteria can also cause the swelling. To reduce the number of false diagnoses this would lead to, a preparation of M. avian, the avian form of tuberculosis, is injected nearby. M. avian is widely present in the environment. It is not harmful to cattle, although their immune system reacts to it.
The swellings are compared after 72 hours. Statistical studies, rather than an understanding of the underlying biological mechanism, have indicated that if the M. bovis swelling is significantly larger than the M. avian swelling, a reaction to M. bovis has occurred. The animal is then deemed to be a ‘reactor’ and killed.
This test is known as the ‘skin test’ (or more properly as the single intradermal comparative cervical tuberculin test).
A blood test, the gamma interferon test, is also used on some occasions as an ancillary test. It evaluates the same immune response but is conducted in the laboratory. There are documented cases of wildly differing results from using the two tests on the same herd.
If an animal fails either the skin or blood tests it is slaughtered.
Serious concerns (many of which we will explain on this website) exist among scientists, farmers and the wider society about the accuracy of the test. Even Defra admit the tests are ‘imperfect’.*
* See page 13 of this document