As badger culls begin, could one pioneering vet’s bovine TB test end the slaughter?
Patrick Barkham. The Observer. Sun 15 Oct 2017.
Research at a secret location in Devon may help eradicate bovine tuberculosis without a single badger being killed, says leading vet
A pretty stone farmhouse sits in a bucolic green valley, surrounded by airy cowsheds. It looks like a timeless West Country scene but is actually a pioneering farm, where cutting-edge science is helping to solve the hugely controversial, multimillion-pound problem of bovine tuberculosis (bTB).
As an expanded badger cull gets under way this autumn, in which 33,500 animals will be killed to help stop the spread of the disease, a leading vet, Dick Sibley, believes this Devon farm demonstrates a way to eradicate the disease in cattle – without slaughtering any badgers.
Sibley’s trial, at a secret location, was halted earlier this year when two new tests to better identify bTB in cattle were deemed illegal. But government regulators have now given the vet permission to continue. His work is backed by rock star-turned-activist Brian May, whose Save Me Trust last week began a four-year programme of vaccinating badgers at the farm against bTB.
The family that owns the farm, which has 300 milking cows, turned to Sibley in despair after being virtually shut down with bTB for five years. Because of the disease, their cattle cannot be sold on the open market.
“We had nothing to lose,” said the fourth-generation farmer, who asked to remain anonymous out of fear of interference from extremists on both sides of the argument. “We want to get rid of TB, it’s costing us a lot. Any technology would be better than the old bTB test.”
Despite four years of badger culling, bTB continues to rise in England, and 30,980 cows were slaughtered in the year up to June in attempts to control it, an increase of 4%. Farmers, as well as wildlife campaigners, are increasingly critical of the cattle test for bTB, which misses many cases, leaving undiagnosed cows to spread the disease within herds. In 2015, 16% of English bTB “breakdowns” were only detected in abattoirs, after supposedly healthy cows had been slaughtered.
Sibley is pioneering two new tests. The phage test, developed by microbiologist Cath Rees of Nottingham University, uses a bTB-invading virus to “hunt” for the live bacterium. It is detecting bTB in cows on the Devon farm months before they test positive with the traditional “skin test”: 85 cows have tested positive with the phage test despite all being found disease-free by the conventional test.
Farmers then need to know if infected cows are infectious. For this, Sibley uses a second test, qPCR, developed by Liz Wellington, life sciences professor at Warwick University. It detects bTB in dung, showing if a cow is “shedding” – spreading – the disease. If it is, the cow is slaughtered even though the conventional test suggests it is healthy.
Both professors have given Sibley free use of their new technologies, and the tests have shown that supposedly healthy cows are the “hidden reservoir” of bTB on the farm. But Sibley said what farms need as well as better testing is better risk management and more resilient cows. “I’ve never cured a cow with a test,” he said.
The farm is an intensive dairy operation that keeps its cattle indoors once they are fully grown and milks them robotically – some cows produce 15,000 litres of milk each year. “If you don’t give that cow everything she needs, and keep the disease away from her, she will crash and burn,” said Sibley. “It’s just like athletes: if there’s a bit of E coli in the Olympic village, they all go down.”
TB – in cows as well as humans – is traditionally a disease of bad living conditions, so the farm’s barns are airy. There are fewer cows in each barn compared with a typical dairy farm, walkways are cleaned three times a day, and regularly changed drinking water is held in “tipping troughs” that are kept scrubbed clean. Dung falling into troughs is likely to be a key transmitter of the disease.
After studying each cow’s history, Sibley believes mothers often spread the disease to their calves at birth. The farm is combatting this by building a new maternity unit with rubber floors that will be disinfected after every delivery. Colostrum – the crucial first milk that boosts a calf’s immune system – is harvested from each mother but pasteurised before it is fed to each calf, so it won’t spread disease.
Leading vet Dick Sibley is trialling new testing methods for bTB that will detect the disease much earlier in cattle. Photograph: Jim Wileman for the Observer
After being “shut down” for five years, the farm had its first clear test last year. It hopes to be clear of all restrictions within 12 months. But Sibley says that removing the disease from cows without tackling diseased badgers is like “crossing the road and only looking one way”.
Farm CCTV reveals that no badgers come close to the cattle sheds, but Wellington’s qPCR technology tested badger latrines and found local badgers were shedding the disease: 30% of 273 faecal samples contained the bacterium. Young grazing cows are potentially exposed to the disease.
“We have to accept that the badgers are a risk,” said Sibley. “We either kill them, fence them out or, more constructively, vaccinate them to reduce the risk of infection in the environment.”
May’s ‘Save Me Trust’ is funding badger vaccination around the farm. The Queen guitarist became a hate-figure for some farmers when he suggested that if bTB was such a problem they should stop rearing cattle. But he has been working behind the scenes for several years to support farmers.
“I’m very, very hopeful that Dick Sibley has the answer,” said May. “I hope it works out, not just for this farm but for the whole of Britain. That would take away this awful polarisation between farmers and the public and animal welfare groups.”
A global shortage of BCG vaccine stopped May vaccinating badgers last year and he points out that the farm has virtually banished the disease without touching a single badger. “If badgers are running around with bTB and the herd has been cleaned up with advanced testing, that really makes you wonder whether badgers are contributing to the disease,” said May.
While some epidemiologists have privately expressed frustration that the government has not yet adopted new cattle-testing technologies, Sibley said the regulators move slowly. “The authorities must have rock-solid evidence in case they end up in court. I predict that in five years time phage and qPCR will be in the toolbox for farmers.”
Other bTB-hit farms are interested in Sibley’s approach and May’s charity has pledged to help meet veterinary costs. In Wales, farms with chronic bTB are receiving special support from the Welsh government and could be among the first to adopt the new techniques. Christianne Glossop, Wales’ chief vet, said: “I have known Dick for many years and have great respect for his work. I am also well aware of his current trials and will be keeping a close eye on the results of his pilot in Devon exploring innovative new testing methods.”
The Devon farmer admits he has been surprised by his success. “This test is showing the light at the end of the tunnel. I’m excited that it could help us get clear of the disease and help other farmers in the future.”
THE CULLING DEBATE.
A zoonotic disease – one that can jump from animals to humans – bovine tuberculosis (bTB) caused thousands of human deaths until the pasteurisation of milk began in the 1920s. It was then almost eradicated from British cows with the widespread slaughter of herds in the 1950s.
However, in 1971 it was discovered that cows had passed the disease to badgers after a dead badger was found on a farm in Gloucestershire. The find led to five decades of debate and scientific uncertainty, and it is still not known what proportion – if any – of cattle TB cases are caused by badgers. The scientific consensus is that cows and badgers pass the disease between them but the precise method of transmission is also not known. Epidemiologists believe it is most likely via animal faeces.
Cattle TB has risen steadily since the 1980s and cost £500m in compensation to farmers in the decade up to 2013. That year, badger culling began in two “zones” in Gloucestershire and Somerset. It has since expanded to 21 zones in England. Ireland, the only other country with a bTB problem, also culls badgers.
Pro-cull farmers argue that reducing badger numbers will reduce bTB in the environment. No data has been published on the impact of four years of badger culling on cattle TB, but many scientists question the cull’s effectiveness.