SCOTLAND REMAINS the envy of its UK counterparts in its efforts to eradicate bovine Tuberculosis (bTB), however, a post-EU era presents a new farming landscape and farmers have been urged not to get complacent in their efforts to control the disease.

Scotland was officially granted bovine TB free status (OTF) from the EU in 2009 and with the exception of a few isolated incidents in the south-west and north-east parts of the country, this has stood strong for over a decade.

Currently, Scotland operates a herd testing regime of once every four years, but some herds identified as ‘low risk’ will be exempt from this. There is also the addition of carcase surveillance in abattoirs, which can be used as an alternative disease management tool for some beef suckler units.

With Scotland renowned worldwide for its high health and welfare status, the pressure is on to ensure this is not compromised as new trade deals are struck and livestock trade continues across its borders.

The SF caught up with representatives of the British Veterinary Association to hear how Scotland has maintained its OTF status thus far, the challenges with the current testing regime, new vaccine trials which are underway, and why a more joined up approach between farmers, the government and vets could empower farmers to control the disease.

BACKGROUND

Historically, there were high levels of bovine TB across the UK until accreditation in the 1930’s, then levels began to decline until the 1970’s where there was a rise in cases primarily in England and Wales. Cattle vet and representative of the BVA Scottish branch, Gareth Hateley, attributed this spike in part due to changes in farming practices as silage came on the scene.

“Farmers started to move away from hay-based systems to grass and then maize based silage, which attracts badgers who are known to be a reservoir of the disease,” said Mr Hateley. “Badgers are of course only one part of the problem, but here in Scotland there isn’t that intimacy between badgers and Scottish farms and maize doesn’t grow as well past Carlisle."

Read more - Study reveals TB transmission between cattle and badgers

Badger ecology expert from the University of Exeter, Dr Andy Robertson, gave some insight in to why this might be the case: "Badger density is strongly driven by habitat, with badger numbers generally higher in lowland areas where there is good cattle grazing and arable fields to provide foraging opportunities. Essentially where the habitat is good for cattle, it’s good for badgers. However, even in areas of Scotland with more suitable badger habitat (southern/eastern Scotland) surveys estimate that badger densities are less than half those recorded in South-west England.

“A lower badger density may be one (of many) reasons why bTB is so much lower in Scotland than England, as this reduces the likelihood that the disease will become established and spread in wildlife,” he explained. “Although, it should be noted that in some localised areas of Scotland badger densities may be similar to parts of the edge area in England, where bTB is currently increasing. The recent TB hotspot (and corresponding badger cull) in Cumbria also shows that cattle movements can infect badger populations in new areas where badger densities are typically low. Scottish farmers should still take precautions to reduce the risk of importing disease in cattle, and limit opportunities for transmission to badgers (e.g in feed stores and yards) to maintain a healthy badger population,” he urged.

The Scottish Farmer:

Badgers are known to be a reservoir of the disease, however this has mainly been an issue for farmers south of the Border (PC: Ben Birchall/PA Wire)

Scotland has the advantage of having its farms further spaced apart and with less intensive farming units. This has made it much easier to curb the spread of disease between farms and regions and was a huge factor in helping Scotland achieve its OTF status in 2009.

Mr Hateley pointed out that this doesn’t mean Scotland has had no incidences of the disease in the past decade.

“There have been a few explosive outbreaks of bovine TB in Scotland, but in all situations, it could be demonstrated that the disease had not spread to neighbours and had been contained and dealt with,” assured Mr Hateley. “This in turn has ensured that the country remains as a whole disease free.

“Bovine TB is hardest to eradicate in areas which have been strong with dairy – the south west is one area. When we have had cases up in Aberdeen it has been from animals brought in from south of the border.”

Junior vice-president of the BVA, James Russell, explained that there can be incidences where false positives can occur in testing. “A test with 99.8% specificity will identify the very occasional false positive animal in a negative national herd.”

In Scotland there is also a reliance on slaughterhouse surveillance, where carcasses are checked for lesions. If a herd slaughters more than 40% of its stock a year, then they are exempt from herd tests as the slaughterhouse surveillance covers them.

Mr Hateley added that by maintaining OTF status, Scotland has been able to focus its efforts on tackling the likes of Bovine Viral Diarrhoea (BVD).

TESTING

The Tuberculin skin test is the primary test for bovine TB in the UK and is supplemented by the interferon-gamma blood test. The skin test involves injecting two different types of Tuberculin into the skin of the neck at two adjacent sites to trigger a localised allergic reaction and three days later animals are checked to see if a swelling or lump has appeared.

Where the skin test identifies an infected herd, the gamma test – which involves a blood test - can be used to identify individual animals with greater certainty. It is often used in conjunction with the skin test but does have some false positives, so it is only used in herds where disease has been confirmed by the skin test.

The disease is slow-burning and well adapted to living with the host for a long time in areas where an animal can’t produce an immune response until the disease is well established.

Early failure to detect the disease has called in to question the efficiency of the skin test. Test sensitivity ranges between 50 - 80% which means that between 20 and 50% of infected cattle could be missed by the test.

The Scottish Farmer:

Following a Tuberculin skin test, animals are checked to see if a lump or swelling has appeared

The BVA has urged the Government to explore whether the skin test is the best way to strip disease out of our herds and to consider other tests which could replace it.

“The Welsh recognised where herds have been under restrictions for 18 months when they went through two short interval tests and got clear, that 25% would break down again with the same strain of TB within a year to 18 months later,” explained James Russell. “The conclusion they drew is the herds were never clear in the first place.

“The skin test doesn’t pick up on infection early in the disease process, and in larger herds with circulating infection it may be difficult to identify reactors more quickly than they are able to spread disease within their population. This begs questions as to whether it is the best tool we could be using to eradicate disease from known infected herds. We know there are tests out there that claim to have better early detection rates, and some are accredited by the World Health Organisation. What we are saying is, let’s try to understand how they might fit in to the testing landscape here.”

Bovine TB is most common in dairy cattle. This is suspected to be due to the nature of how these cattle live together in large numbers, often under one roof, sharing the same space and access to feed and water. In parts of the south west of England - which is home to a lot of dairy cattle and has suffered from chronic TB over the years - the current test can’t keep up with the rate of spread of disease in big herds.

“Disease knows no boundaries,” added Gareth Hateley. “We must consider the UK as a single epidemiological unit, there is always potential for it to come into Scotland through the movement of livestock across the Border.

“Recognising diseases like bovine TB is everybody’s responsibility, we need to continue to work collaboratively between the devolved nations to improve our TB strategy. There is no silver bullet to eradicate the disease, but work is beginning on the vaccine trials and a DIVA test which will give us more tools in our box to work with.”

BVA POLICY POSITION

In recent weeks, the BVA launched their updated policy position on controlling and eradicating bovine TB and Gareth Hateley was part of the group who designed it.

Read more - Bovine TB eradication plan: Vets set out new position

Some of the new policy recommendations include rewarding good biosecurity practices, simplifying and prioritising research priorities and introducing systems to allow greater data sharing between government, vets and private vets.

“All the things that are included in our policy statement in terms of biosecurity and good farm behaviour in terms of buying and trading practices are all extremely relevant to Scotland,” said Mr Hateley.

“In some sense, there is slightly increased risk in Scotland as testing only takes place every four years and a lot could happen in that time period. This means that Scottish farms have to be double as vigilant about biosecurity and that their trading practices are secure and well thought out. I urge farmers to check what people say, not to make assumptions and don’t rely just on post-movement testing.

“Because disease is relatively infrequent in Scotland, there is the tendency to become complacent. The same principles and intensity of biosecurity applies wherever you are – there is no room to relax,” he warned.

TRACEABILITY

Improving the traceability of our livestock is a key priority as the UK looks to leave the EU and enter in to new trade deals, where world-leading standards of livestock traceability could deliver a competitive advantage and make the UK more resilient and responsive to animal disease.

There is currently a real drive between devolved nations to work more collaboratively on recording livestock movements between countries, which would mean linking the likes of ScotEID – Scotland’s livestock traceability system – with its UK counterparts.

In England, the development of a Livestock Information Programme (LIS) looks to pull together a central database of information, tracking the movements and medical records of all UK livestock and could, long- term, allow more cooperation between government, vets and farmers as the history of an animal would be available at the click of a button.

James Russell explained what this tracking system could mean in terms of bTB regulation: “This new programme will be a step change in terms of traceability of stock. It will be introduced steadily and in a deliverable way but in the fullness of time, we hope to be able to access the full bTB history of an animal and any herd which that animal has belonged to, which will help people make decisions on appropriate testing and purchasing of stock,” he explained.

“One of the first things being looked at is an E-medicine hub which would mean any medicine that has been given to an animal is automatically on record and is attached to their ear tag. This is still often done manually and can mean vets don’t have the full information at their disposal when checking a herd.”

“A big thrust of our own policy is about empowering farmers and vets, so they have control over what happens on their own unit; how they test; what they test and what they do with results, over and above the statutory requirements. We want to give people all the knowledge, so they then have confidence to make informed decisions when it comes to things like purchasing livestock.”

The Scottish Farmer:

Scotland operates a herd testing regime of once every 48 months, but some herds identified as ‘low risk’ will be exempt from this

VACCINE TRIALS

A major breakthrough in bTB research of recent is the news that vaccination trials are set to get underway in England and Wales.

Read more - TB vaccination breakthrough

The BVA has said that a viable cattle vaccine could be a ‘game changer’ in the control and eradication of the disease, used in combination with a validated DIVA test – Differentiating Infected and Infected Animals.

Trials are to be conducted over the next four years and if successful, there is hope for the deployment of a cattle vaccine by 2025.

“If this test delivers, what we would have for the first time is the ability to differentiate between infected and vaccinated animals which would be a really useful tool,” said Mr Russell.

“The vaccine itself is nothing desperately new, it is based on the BCG vaccine but what we need to know is how that works with cattle. We have never had cause nor opportunity to do this in the past. Initial trials will look at safety and if the vaccine generates an immune response in the animal, then there will be trials on its effectiveness of stopping animals catching TB.

“This is something we have been really excited about for a long time; it could even be proved that the DIVA test is more successful than the existing skin test because of the nature of the Tuberculin to be used.”

POST-BREXIT POLICY

As the UK prepares for its departure from the EU, questions regarding Scotland’s high health and welfare status and maintaining future standards remains top of the agenda for the BVA,

“The EU was and will remain our single biggest block trading partners and therefore it would be foolish if our bTB policy wasn’t in-line with that,” stressed Gareth Hateley.

“One of the UK’s strongest selling points is its animal health and welfare standards and my message to the UK Government would be ‘dispense with those at your peril’.

He did point out, that as Scotland looks to develop its unique system of funding support for agriculture that there could potentially be rewards for delivering on high animal welfare.

James Russell reiterated a similar sentiment: “It was a manifesto pledge of the UK government to ensure animal welfare standards were not compromised in any trade deal. We are engaged in conversations with both Defra and the Department for International Trade alongside their new Trade and Agriculture Commission. We have been given reassurances that farming and veterinary representation will be considered in its working groups.

“Beyond that, we remain concerned that animal sentience is still not enshrined in legislation. What we recognise is that it is possible to produce food more cheaply by compromising on welfare standards.

“If we do not secure protections from importing food produced to lower welfare standards then this risks pricing our higher welfare food out of the market. The consequence of this for animal welfare is bad. Either we have to reduce our production standards to compete, or see

farmers cease production altogether.

"The important strategies we are pursuing in terms of traceability and eradication of endemic disease will not be able to be maintained. These do form some part of the cost of production for our farmers.”

The Scottish Farmer:

Bovine TB is most common in dairy cattle and in parts of the south west of England, the current skin test can’t keep up with the rate of spread of disease in big herds

CLIMATE CHANGE

With rising temperatures brought about by climate change, disease threats to the UK have heightened and with warmer climates could bring new challenges to Scotland’s OTF status.

“Diseases which previously would never have been recorded in northern Europe, such as Bluetongue, we are now seeing,” stressed Gareth Hateley. “This is a sub-tropical disease but now we have it in northern Europe.

“This is a combination of climate change leading to changes in the vector midges’ distribution and globalisation (the increased movement of animals across borders) enabling this to happen.

“There is also something to be said for the agents which carry disease such as midges with Bluetongue, others are vector borne which could easily come into our country,” he warned.

“Most governments are recognising the severity of disease threats and the strong likelihood that some diseases will be zoonotic - meaning they could spread to humans.”

CONCLUSION

As Scotland looks to maintain its OTF status in the future, there will need to be a joined-up approach to bTB policy post-Brexit and information available on individual farm statuses not just regions of the UK.

James Russell concluded: “Part of the BVA’s mission is to give confidence to farmers to make informed decisions on purchasing cattle, including being able to choose to purchase from areas which for many years have sent a warning sign to buyers due to bTB being endemic in the area.

“If there is more data sharing between farmers, vets and the government, this will encourage secure informed purchasing between individual farms who can feel empowered and confident in making good business and health decisions.”