New test can identify TB in badger droppings, say scientists

Scientists have claimed a “breakthrough” in the fight against bovine TB following the development of a test to identify diseased badgers through their droppings.

The badger (Meles meles) is a reservoir of Mycobacterium bovis – the bacteria which causes bovine TB – and exposure to infected badger faeces may be a route of transmission to cattle.

However, researchers at the University of Warwick, led by Professor Liz Wellington, revealed they have developed an M bovis test that can be used on badger faeces.

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They said the test is able to tell farmers if badgers on their land are infected with TB and pose a threat to cattle.

Dr Hayley King, part of the “WarwickPCR” research team, said: “We now have a test that can detect infection in badger populations without trapping a badger at all.

“The test allows us to see if there is M bovis bacterium infection in a badger population just by looking at faecal samples in badger latrines.

“It could potentially be a way for farmers to monitor biosecurity in cattle, slurry, the feed, water and pasture.”

“It could potentially be a way for farmers to monitor biosecurity in cattle, slurry, the feed, water and pasture”
Dr Hayley King

The test works by detecting bits of DNA in badger droppings and monitors how many copies of M bovis bacterium are present.

The researchers say blanket badger control methods are “too costly and logistically challenging” to roll out on a large scale, limiting TB control interventions.

However, they believe they can use the test to identify potential TB hotspots by detecting M bovis in badger droppings.

Identifying TB hotspots could help design more effective, targeted ways to remove only diseased badger and spare healthy ones, rather than a “blanket” culling approach.

During the project, the group found more M bovis infection in badger faeces in summer than in any other season, suggesting the risk of disease transmission may vary throughout the year.

The researchers suggest a summer sampling programme could be used around the edges of the known TB infection hotspots, such as the South West, to monitor the spread of infection.

Because the test is much cheaper than trapping and testing badgers, they believe the take-up of this method would allow large populations of badgers to be monitored and many hotspots to be identified.

The 18-month project, funded by Defra, ended in January 2014.

But the results were published only last month in the Journal of Clinical Microbiology (PDF).

Defra is reviewing the results of the project and the research team hopes that funding will be extended.

The spread of bovine TB is a major economic burden on the cattle industry in the UK.

According to Defra, almost 33,000 cattle were slaughtered in the UK last year because of TB, costing the taxpayer an estimated £100m in compensation payments to farmers.