Bovine tuberculosis testing - we really need to talk

| 11th September 2017
Honey, in her sett, is just one of the potential beneficiaries, both human and animal, of a breakthrough test for bovine TB.
Honey, in her sett, is just one of the potential beneficiaries, both human and animal, of a breakthrough test for bovine TB.
Are the shortcoming of existing cattle TB tests soon to be exposed by a simple, clever blood test that has been waiting in the wings? The development may shine light on practical compromises in the extended, failing fight against TB in England - at huge tax-payers expense. Biologist TOM LANGTON looks at a growing dilemma in the world of bovine TB cattle testing
Is this at last the beginning of the end for bovine TB?

As bovine TB spreads across the UK, it is no secret that the new government, like the previous is in turmoil over its response.

Chief Scientist Ian Boyd and now Chief Vet Nigel Gibbons are both leaving their roles.

Not specifically because spread of a disease that they have been unable to stop, but their time is up and they can slip away from the deteriorating situation. Both made it plain at the March 2017 London bTB conference that industry behaviour is holding progress back.

The background is not hard to work out.  From the Great Recession of 2007 and the European debt crisis, a decision was made to try to force growth in the UK beef, dairy and leather industries.

After the ravages of the 2001 Foot and Mouth Disease on the National Herd, the plan was to attempt this without the necessary restraint and extreme caution on cattle movements that dealing with bovine TB (bTB) demands. 

Years of removing cows

Mission-impossible? It will not be the only area where around 2010, decision makers gambled heavily, knowing that judgement day on ‘hide-now-pay-later’ approach might somehow be avoided.

‘Save the economy at all cost’ may include ‘bankruptcy later’ with heavy collateral impacts on people’s lives, but hey, we live in a changing world and profit comes first.

In Wales, more sensitive testing using the gamma interferon bTB test has made useful progress, with a 47 percent reduction in Bovine TB herd breakdown since 2008.

Elsewhere, including the High bTB Risk Area of England, the use of the old tuberculin skin test alone has not. This is also because cattle farming practises have changed and cattle breeds and health have also altered since bTB eradication in the 1960s.

Is this at last the beginning of the end for bovine TB?

It may be that 50 more years of removing cows that react most strongly to the skin test has selected those that react less to it. Failure to give a positive result may also be due to small amounts of bTB bacteria that may rest dormant or in a latent state, hidden in healthy looking calves and cows.

This uncomfortable truth

These animals escape the skin test and sometimes a proportion of the gamma tests by simply not being active enough to be detectable, but they are capable of emerging and leading to a new breakdown at any time.

Whatever has changed, it is quite clear that gamma interferon testing has helped reveal that even if an infected herd passes two final 60-day skin tests and is declared TB-free, there is a chance that in over a quarter of them, bovine TB ‘carriers’ remain.

They then may go on to become infectious, particularly following the process of small numbers being frequently traded to new farms on a very regular basis. This is the behaviour that senior European veterinary experts have been repeating for the last 10 years or more that we are crazy to be doing. In fact the view is that we are a joke.

All this is known and not really contested. If the skin test does not weed-out 90 percent of infected animals but 80 percent or sometimes just 50 percent then the millions and billions of pounds spent on testing and compensation are effectively wasted and the epidemic creeps more slowly across England and into Scotland and Wales or the countries still foolish enough to import English cattle under present circumstances. 

This uncomfortable truth comes with the acceptance that the cows that react to the skin test but are not found to have visible lesions at the slaughterhouse were in fact all, or all but a few, infected after all with bovine TB.

Immune response in animals

However, recent findings indicate that that those animals reacting to the test but with bumps not big enough to send to slaughter (the so called inconclusive reactors) are also almost all TB carriers and potentially provide an ongoing source of disease outwards to the National Herd.

This is a shock to the system for bTB modellers too, who looking back on years of bald assumptions may also resist the implications, due to the pile of papers now needing a revisit. Modellers thrive on death and uncertainty. They may think bTB is slow to spread and to become contagious rather than quick to spread and good at hiding and passing on. 

But now there is a new kid on the block. No longer a baby, it is up and walking but not as steadily as it might be. Phage RPA or the ‘phage test’ is a clever method, adapted from human TB diagnostic test.

It uses a virus made harmless, that finds, invades and multiplies only in TB bacteria, to become a marker confirming the presence of the bacteria itself. Why is this new? Because in the past, the skin and gamma tests have detected an immune response in animals – signals that they may be diseased and that the body is recognising infection.

They do not however overcome the problem when an infected animal suggests it is not infected, which can happen for a very wide range of reasons. 

An encumbrance

With Phage testing, for the first time it is possible to detect tiny amount of TB bacteria in tissue, blood and even milk. What’s more it is far quicker than the skin test, with results available in 6 hours. Governments around the world are excited about Phage testing, as a new dawn if not a magic bullet.

What’s not to like? Well the USA and Canadian government are giving awards to Phage research and rolling out application programmes to address many issues, as Phage can be used for different types of bacteria, not only bovine TB. It can also be used for a wide range of animals. 

There has been a pilot project here in Devon. But last year, Defra seemed to more than turn their nose up on investigations trying to determine the value of this new technology. You would think that the potential and need in the face of the current bTB emergency was so great that they would be funding and accelerating the potential. All very strange?

There is also a feel that senior scientists in government agencies, shovelling large amounts of public money into cattle vaccination projects in university departments for which they sometimes have a rather close interest, is becoming an encumbrance.

However, cattle vaccination requires a holy-cow; the ever illusive Divergence or DIVA test to distinguish between infected and vaccinated individuals. Otherwise all vaccinated animals will appear to be infected as they give a positive immune response. Amazingly Phage testing test now provides that breakthrough too. So why-oh-why, the hold-back?

Loss of lucrative funding

Well the fact is that the measured use of vaccination could have been used for years to help strategically contain manage and reduce bTB, were it not for globalisation and the wish for the UK to maximise sale of beef and dairy exports at all costs despite the bTB crisis.

Also the Ministry always struggles with ‘strategic’ in its free market bubble and heavily cut-back offices. The constant pushing back of vaccination as the probable long term solution has gone from being almost forgotten, to suspicious, to yet another embarrassing research gravy train for friends and fence sitters.  

With Phage testing, however, vaccination is no longer a blind alley for UK and Ireland to sigh theatrically about, stating sadly with lowered voice that ‘it’s going to be another ten years at least you know’. The world has woken up to this even if most politicians have not.

Those in vaccination research might be eyeing Phage testing, with a ‘why didn’t we think if that first’ thought and realising that actually on its own, without vaccination, Phage-RPA may be the bigger part of the solution.

Is it the loss of lucrative funding by a small sector of the comfortable research bodies that has been holding back farmers rights to the best services they should have, to tackle the appalling TB crisis? Ruining farms, people’s lives and breeding stock? 

Financial-loss pendulum

As this becomes clearer and more widely known, Defra is enacting a slow volte-face in order to extract itself from its nasty risk profile. It knows all this and might be sweating about the implications.

It is quietly approving now, of the work in Devon on Phage testing and a few tentative further trials in Cornwall. Perhaps also some use in Wales that is stuck just using gamma (which in some countries is dogged by manufacturing glitches) and the skin test.

Wales is casting around for something else to make progress with, particularly the 65 TB persistent herds in and around Pembrokeshire. Adding badgers to a rather tired shopping list without the required ingredient.

But why still the slow-train on what Welsh Government officials describe as a war-zone? bTB is a massive eye-wateringly expensive countryside disease crisis.

And the financial-loss pendulum can swing back in favour of the public and farmers who, as in Ireland, have paid the billion pound bill for dud skin tests for decades and the hopeless, cruel badger decimation using snaring and shootings.  

Prevarication in the bTB war zone

No need to waste £100 million a year with a foolishly distant 2038 and (can you believe it?) 2065 strategy in Northern Ireland. Where are the National Audit Office and the Public Accounts Committee?

It seems crazy that government did not pick up Phage last year or this year and run with accelerated trials that might take just a few months. Who exactly is holding it back?

So where now is the political hold up – the grit in the Vaseline? Well it is this. Defra can huff and puff about rules and regulations and setting precedents from bringing new solutions forward but that is all prevarication in the bTB war zone.

With its absorbed old MAFF component it has long known that the English High Risk Area, especially Cornwall, Devon, Somerset and beyond is riddled with TB.

Even the Edge Area and beyond has growing hidden TB time bombs as this year our current cattle movements system releases bTB into Cumbria and Scotland.

Blaming badgers 

The main political problem is that any serious attempt to tackle bovine TB will shrink the UK cattle business because in any realistic effort there are simply not enough ‘clean’ cattle to re-stock . The trade ‘volume’ - that horrible term that applies to machined goods as much as cows - would shrink, including exported powdered milk to Asia etc. 

The hold-up is the need, when routing out TB, to remove perhaps up to a third or more of cattle to clear a UK herd. It is also the need for establishing strict long-term quarantine capacity for all farms and between adjoining farms.

That may be a logistical headache and short-term one-off cost, but could be done in months and years not decades. And it is a case of the sooner we start the more we can save and the fewer farms suffer.

This is why since 2010, even gamma testing which catches many but not all of those left behind by the skin test has not been funded or properly promoted for use in the HRA.

For some time now, the existence of TB carriers in clear-testing herds has been known. So blaming badgers became the name-game. The ‘carrot’ alongside full compensation to help keep the NFU quiet.

Improve farm biosecurity

This is also is well realised by the senior government officials, veterinarians and industry reps and thinkers pulling the strings. They would rather talk up a broad range of anti-TB measures that may slow the spread, but not deal with stopping a disease that has to be stopped. Now no one now wants to possess the problem and its sour origin. 

Equally, no one saw Phage coming. Gove has only recently been briefed. The past strategy has been to hoodwink most farmers and the public into thinking there is a viable solution in place when there is not, that approaches are working when they are getting worse and to use taxpayers money to subsidise commercial intensive livestock export businesses and producers on the back of the public, while farmers and cow herds suffer. Scandalous?

Well, we all know it is a wicked world and that stuff happens. But actually Phage testing has come along to peel away the delusion and deception. It is now possible with the clever, not so new but un-promoted test to clear out all of this nonsense at last.

And yes, we do need to maintain and improve farm biosecurity. We do need to monitor TB in wildlife when TB in cattle comes down, to see how long it remains and to study that properly.

We could start immediately by using Phage tests for compulsory pre-movement testing of all cattle to start breaking the cycle. No conflict with the day- to day skin test testing, if that is what is wanted. But the skin test has had its day. It is now about the hand-over. And until that starts current funds are being sprayed into wind and against wall.

Warts and all

Any losers? Farmers and vets who do the tuberculin skin testing will have a less demanding routine compared with that for skin testing. Vets will work hard to destroy that regular workload and farmers the compensation pay-cheques.

They must surely now be the first to get behind the use of Phage – why wouldn’t they?

The British Veterinary Association and British Cattle Veterinary Association also have something to get really, really excited about and to embrace surely? Oh yes, and the media might cover it in full detail too – warts and all?

This Author

Tom Langton has been a consulting ecologist to government, business and industry and a voluntary sector volunteer, more recently working on assisting small pressure groups in their legal opposition to destruction of species and habitats in Europe.



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