Bovine TB: Badgers and bTB

I am no expert on this subject - so I have here collected a number of documents & text for your information - my own opinion is that intensive farming is unfair on everything , esp. cattle - if farmers were willing to spend on badger proofing surely it would make a bigger impact than culling simply because the main spread of disease is thought to be urine & if cows & badgers do not come into direct contact with one another - (Im sure you can see my reasoning) badgers can be removed from the equasion . Anyway plenty of other animals have bTB , including such creatures as mink & ferrets . Movement of cattle seems to be another aspect .

ISG reports 1998 - 2007

• Final report (PDF 2.5 MB) - June 2007
• Fifth Report (PDF 48 KB) - January 2006
• Fourth report (PDF 715 KB) - February 2005
• Third report (PDF 535 KB) - August 2001
• Second report - (PDF 540 KB) - December 1999
• First report (PDF 200 KB) - July 1998

In 1971 a dead badger infected with bovine TB (bTB) was discovered on a farm that had suffered a bTB outbreak in its cattle herd and this seemed to give backing to the theory that badgers are a cause of TB in cattle.

Over the intervening years, a number of different measures have been tried to control the disease in cattle by culling badgers. None of these was entirely successful. This is why we have now developed a much broader strategy to control cattle TB. This includes, among other things, research into how the disease is spread, development of a vaccine, and possible improvements to the testing and slaughter programme, but also trying to find out, in a scientific way, how badgers affect the disease in cattle.

This page concentrates on what has been tried in the past in relation to controlling the reservoir of bTB in the GB badger population.

The Badger Act of 1973 protected badgers from being persecuted but also allowed the Minister of Agriculture, Fisheries and Food to issue licences to individuals to kill badgers to prevent the spread of disease.

Gassing

By 1975 there were concerns about the lack of controls on who could kill badgers, so MAFF decided that only its own staff, or people under its control, would be able to cull badgers to stop the spread of TB. Gassing was the method used. This was permitted under The Conservation of Wild Creatures and Wild Plants Act 1975.

Zuckerman review

Many people were not convinced that badgers spread the disease and felt that gassing was an inhumane way of controlling badgers, so, in 1980, Lord Zuckerman was asked to review the problem. Gassing operations stopped at the start of the review.

Zuckerman concluded that badgers were probably a significant source of bTB infection and that the high density and close proximity of cattle and badgers in parts of south west England made spread of the disease easy. Because the disease seemed to have spread since controls stopped at the start of the review, he advised that control measures should start again. As gassing was considered inhumane, cage trapping, followed by shooting, became the method of killing badgers.

Clean ring strategy

Zuckerman advised that areas should be cleared of infected badgers and kept clear, so from 1982 to 1985 a ‘clean ring’ strategy applied. Under this strategy, social groups of badgers on and around the breakdown farm were identified, trapped and a sample of carcases from these groups were examined. Where infection was found, all badgers in the social group were removed. The ring extended out until groups with uninfected badgers were found. Trapping took place in the cleared area for a further six months to keep the area clean.

Dunnet review

Zuckerman had recommended a further review in 3 years time. This was conducted by Professor Dunnet in 1986, who concluded that some form of badger control was unavoidable. He recommended the use of an Interim Strategy until there was:

a) sufficient data from research and badger removal operations for a further substantive review, and

b) development of a reliable live diagnostic test for bTB in badgers.

Interim strategy

This policy was introduced in 1986 and involved the removal and culling of badgers only from farms where a TB incident had been confirmed and where, following investigation, it was thought that badgers were the most likely cause of the disease.

During the operation of the interim strategy, the annual incidence of bTB has increased in South-West England and has occurred in other areas with no recent history of infection, including the West Midlands and South Wales.

Meanwhile a trial of a live badger diagnostic test was conducted between 1994 and 1996 but was stopped because of the poor sensitivity of the test and problems with the trial.

Because of the continued increase in TB in cattle, it was clear by 1996 that the interim strategy was not working so the government asked Professor John Krebs to carry out a further review.

Reports

All the documents below are in PDF format.

• Overview of research into carbon monoxide fumigation as a method of culling badgers to prevent the spread of Bovine Tuberculosis (20 KB)
• A Computational Fluid Dynamics Assessment of Factors which will Effect Carbon Monoxide Dispersion within a Simplified Badger Sett (1.5 MB)
• Fumigation of a Y-shaped tunnel using a de-tuned petrol vehicle engine (500 KB).
• Computational Fluid Dynamics (CFD) Modelling of Carbon Monoxide Dispersion within a Badger Sett (800 KB)
• A Comparison of a Computational Fluid Dynamics (CFD) Model with Experimental Results of Carbon Monoxide Dispersion within a Purpose Built Tunnel System (500 KB)

• Fumigation of a Y-shaped tunnel using a portable CO generator (700 KB)
• An investigation of the ability of computational fluid dynamics (CFD)
  to predict the dispersion of carbon monoxide in soil and other porous media (1 MB)
• An improved model for simulating the movement of carbon monoxide in a dry soil tunnel (200 KB)
• Review of effectiveness, environmental impact, humaneness and feasibility of lethal methods for badger control (400 KB)
• Further development and validation of a CFD model of gas diffusion within a soil tunnel (1 MB)
• Humane despatch of badgers captured in cage traps – the feasibility of using frangible ammunition (1.3 MB)
• Trials of a body snare designed to catch and hold badgers (300 KB)
• Shooting as a potential tool in badger population control. Report to Defra by The Game Conservancy Trust (PDF 650 KB).

Bovine TB: The tuberculin skin test

The primary screening test for TB in cattle in Great Britain is the single intradermal comparative cervical tuberculin (SICCT) test, which is commonly known as the tuberculin “skin test”. The tuberculin skin test, which is used throughout the world to screen cattle, other animals and people for TB, is the internationally accepted standard for detection of infection with Mycobacterium bovis (M. bovis), and is considered the best test currently available for detecting TB in live animals. Many countries have eradicated bTB through the systematic application of the tuberculin skin test alone and the slaughter of all test reactors.

The test involves injecting a small amount of tuberculin (a sterile antigenic extract obtained from a culture of M. bovis or other organisms of the same family of bacteria) into the skin of the animal. In most cattle infected with M. bovis, this will cause the animal's immune system to react to the tuberculin and cause a localised allergic reaction (swelling) of the skin a few days after the injection.

Cattle are sometimes infected with other types of mycobacteria which may cause the animal to react to the test. So that we can distinguish between animals infected with M. bovis and those infected by other mycobacteria, we also inject the animal with tuberculin produced from Mycobacterium avium, an organism that can cause TB in birds. The size and nature of the reactions to both tuberculins (‘avian’ and ‘bovine’) is compared (hence the term single intradermal comparative cervical tuberculin test) to determine whether the test result is considered positive, negative or inconclusive.

The Veterinary Laboratories Agency (VLA) has produced a report analysing the comparative field performance of tuberculins (164 KB) produced by VLA Weybridge and by Dutch manufacturer ID Lelystad between 1 January 2005 and 31 March 2007.

Further information on the diagnostic accuracy of the skin test can be found in Defra’s online booklet ‘Dealing With TB In Your Herd’ (643 KB).

 

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