April 14th, 2023
TB, Badgers and CHeCS
This veterinary webinar was presented with members of the British Cattle Veterinary Association (BCVA) members in mind. A captive audience therefore, and the webinar provides a very up to date summary of the problem of TB and how to control it. There can be fewer more contentious veterinary debates than the one surrounding badgers and TB. Brexit perhaps, Homeopathy, dropout rates from the profession, and most recently student selection. It is many years since I was a cattle vet-my first foray into the profession. This was a rosy time when TB was virtually eliminated from the country. However even if you are not involved in cattle practice it is almost impossible to avoid the controversy surrounding TB control. There are plenty of people from our profession opposing badger control, even though they are and always have been exclusively small animal practitioners, not to mention the pop stars, politicians and charities. As a vet you simply can’t ignore the subject, whatever your field of work. I have to admit to being confused and therefore I was very much looking forward to having some light thrown on the subject by this webinar from Keith Cutler.
Keith begins by outlining the UK Government policy for the eradication of bovine tuberculosis by 2038 based on:
We are reminded that Mycobacterium bovis can survive for long periods in the environment, has a slow progression to disease following infection, with treatment being difficult. Furthermore vaccinal treatment is poor and diagnostic tests lack sensitivity. Plenty of challenges then!
Control nonetheless is as for any infectious disease and comprises three essentials:
Identify and remove reservoirs of infection
Break transmission pathways
Prevent reintroduction of disease
A consideration of enhanced cattle controls follows including the selective use of gamma testing of all breakdown herds and increased skin testing in edge areas. Allied to this are rules regarding post movement skin testing of cattle.
There is an interesting and insightful discussion on the terms sensitivity, specificity and predictive value and a discussion of the merits of the single intradermal tuberculin test, gamma interferon testing and finally phage testing. This latter detects live Mycobacteria which are then identified by PCR testing. Reportedly it has a very high sensitivity and PCR adds specificity. The question is asked -‘Would these be better options than the skin test for post-movement testing?’
Vaccination is dealt with in one slide and it does not look promising. Stated to be ‘ten years way and has been for the past thirty years’-the time Keith has been in large animal practice. And ‘ with the millions of pounds spent on TB vaccine research in human medicine what chance do we have with cows?’
The question of badger controls comes to the conclusion that initial evidence suggests an increasing reduction of TB breakdowns in cattle herds as the cull proceeds. In other words culling needs to be on going. However the effects of perturbation are explained allied with the weakness of cattle testing contributing to the problem. There is still a lot of controversy and badger culling on its own is not the sole answer to the problem of TB transmission.
For me as a non-expert with little experience, although very interested in the subject, the next part was the more compelling. It dealt comprehensively with badger biosecurity. It would be very interesting to know how compliant farmers are with the following recommendations, which are aimed to reduce cow-badger interactions.
Use of sheeted gates
Badger proof feed and water troughs
Fencing off badger latrines
Not over grazing pastures and therby forcing cattle to graze the higher risk field margins more
There is a lot of practical information in this section with illustrations of the various possible interventions mentioned above. Badgers can urinate millions of bacteria into feed troughs-there is also an illustration with the caption ‘Don’t attract badgers with free dinners!’
CHeCS has an important role in helping farmers manage and possibly eradicate diseases such as BVD, IBR Leptospirosis and Johne’s disease. It is an organisation established in 1999 by the British cattle industry and is jointly owned by: –
The remainder of the webinar summaries the many ways that CHeCS can advise on strategies to eliminate various diseases including TB. The advantage of following through with the recommendations is that there is a greater recognition of efforts that have been made to reduce the risk of TB, and other specific diseases in a herd. In the case of TB this results in annual rather than monthly testing in the edge and high risk areas. Furthermore there is a reassurance about the TB status of animals due to be sold adding economic value to the enterprise.
This is a very practical account of the problems associated with TB control from a well-qualified cattle vet of 30 years experience. It seems obvious to me that the solutions are multi-faceted and that badger controls are just ‘one of the tools in the tool box’, to quote a well-known saying. Questions remain though and I would like to know just how good the compliance on biosecurity is because it seems much more likely to be effective than vaccination. Also 2038 seems a long way off-I am very unlikely to see the disease eliminated if this is true, though like the rest of us I live in hope!
I would like this webinar to be universally available. It is excellent and spells out some of the myths and explains very clearly the pros and cons of current measures in the control of bovine TB. The next few years are going to be very interesting, and hopefully less miserable for affected farmers. .