New research throws light on link between badgers and bovine TB


Badgers like foraging in cattle pasture but very rarely come into direct contact with the farm animals, a new study reveals.

Despite strong evidence badgers transmit bovine tuberculosis (bTB) to cattle, the new research suggests the disease is not being passed directly between them - but instead is finding its way between wild animals and herds through the environment.

The results help to explain why TB is so difficult to control, as badgers and cattle can transmit the disease through faeces, saliva while foraging in the pasture or in drinking water, with bacteria surviving for weeks or even months, researchers said.

But it is too early to advise changes to the plethora of "biosecurity" measures suggested for farmers to protect their cattle, such as fencing off badger latrines, raising water troughs and keeping badgers out of buildings, they said.

Professor Rosie Woodroffe of the Zoological Society of London (ZSL), who has raised concerns about the badger cull which is set to be rolled out nationwide to tackle the disease in cattle, said the results did not increase the case for culling.

And although cattle pasture could be a likely source of TB, the findings do not back housing livestock inside as problems with TB testing could mean infected animals remain in the herd and then are kept together inside - continuing the risk of disease. 

The researchers from ZSL and Imperial College London set out to establish how bTB might be transmitted by seeing how much badgers and livestock come into contact.

They fitted 54 badgers with GPS collars across 20 farms in four areas of Cornwall to map out their territory and see where they foraged, research which revealed they favoured the short grass and worm-rich habitat of cattle pasture.

The team also fitted 421 cattle with collars that measured their position, and 53 badgers with devices that registered when they came to within two metres of the livestock.

Despite there being 2,914 definite nocturnal opportunities for the cattle and badgers to meet, not a single contact was recorded, the study published in the journal Ecology Letters showed.

Using the GPS data from both badgers and cattle to assess where they were at 20 minute intervals, the researchers showed they covered the same ground, but did not do so at the same time - the badgers were staying away from the cattle.

Over 65,000 moments recorded in the study, there was not one occasion a badger and a cow, bull or bullock were within five metres of each other, and only one where the animals were less than 10 metres away from each other.

Prof Woodroffe said: "Do badgers avoid cattle? Yes, they do, they significantly prefer to be at least 50 metres away from cattle, so they love cattle pasture but they hate cattle."

There is strong evidence that badgers transmit bTB to cattle, she said, as well as for cattle to cattle transmission and for livestock to give the disease to badgers. 

"It's more likely this transmission is happening through the environment rather than direct contact," she said.

"We're not quite at the point of having to ask anybody to manage their farm differently at this stage," she said, adding that while they inferred transmission was in the environment, they did not know where.

New research under way will collect 18,000 samples from soil, slurry, drinking troughs and badger latrines - areas used to mark territory - to see where the bacteria is and if it originates from badgers or cattle, in a bid to track the disease round farms.