Researchers make bTB genetic contact tracing breakthrough

Researchers at a Scottish university have revealed that genetic contact tracing to identify the source of bovine TB (bTB) outbreaks could be significant in managing the disease.

In response to a rise in TB rates among wildlife in an area of east Cumbria with no previous infections, experts from The University of Edinburgh examined the DNA of the bacteria that causes the disease taken from cows and badgers that had tested positive.

Joined by the University of York, University College Dublin and the APHA, they found that all bacteria taken from the samples were closely related to each other, pointing to a single purchase of cattle as the most likely source of infection.

Routine monitoring

Researchers say routine monitoring of both cows and badgers could help to manage early outbreaks of the disease, for which control measures cost £100 million each year in England alone.

The newly developed method involves tracking the outbreak by integrating genetic data with spatial locations and contact tracing. This allowed them to compare small changes in the DNA as it spread from one animal to the next.

‘Smoking gun’

Rowland Kao, chairman of veterinary epidemiology and data science at The University of Edinburgh’s Roslin Institute, said: “This was an unusual outbreak in that we were able to trace the infection to a single source – as close to a smoking gun as you can get.

“Badgers are becoming more populous, and farms are becoming bigger and more complex, so the risk of disease spreading from livestock to wild animals will probably persist and even increase as these trends are likely to continue into the future.

“Our findings are very useful for understanding transmission of TB and infection spread in general.”

The study was funded by the Biotechnology and Biological Sciences Research Council and Defra, and is published in the Journal of Applied Ecology.