A new study suggests a novel use of genetic contact tracing to identify the source of a bovine TB outbreak could signal a new approach in managing the disease.
The research comes in response to a rise in TB rates among wildlife in an area of East Cumbria with no previous infections.
Experts examined the DNA of the bacteria that causes the disease taken from cows and badgers that had tested positive.
They found all bacteria to be closely related, pointing to a single purchase of cattle as the “most likely” source of infection.
The BBSRC and Defra-funded study is published in the Journal of Applied Ecology.
Scientists claim routine monitoring of both cows and badgers could help to manage early outbreaks of the disease.
In England alone, control measures cost £100 million each year.
Bovine TB outbreak
In a statement, researchers said:
“Bovine TB is an infectious respiratory disease of cattle that is mainly spread through inhaling virulent particles in the air.”
“The bacterium Mycobacterium Bovis causes it. It can also infect and cause disease in other mammals. These include humans, deer, wild boar, goats, pigs, cats and dogs.”
Those involved in the study included:
- Universities of Edinburgh and York;
- University College Dublin;
- UK Animal and Plant Health Agency.
They developed a method of tracking the outbreak by integrating genetic data with spatial locations and contact tracing.
This enables them to compare small changes in the DNA as it spreads from one animal to the next.
According to research, the outbreak began with an infected cow brought to a farm in the region from Northern Ireland.
The disease passed among cattle, infecting an increasing number of cows. It then spread throughout the local badger population, before passing back to cows in a cycle of infection.
Experts suggest that their approach is an effective way to model the spread of infectious diseases. They may apply it to understand the complex spread patterns of other diseases.
Professor Rowland Kao, chair of Veterinary Epidemiology and Data Science at the Roslin Institute and lead investigator of the project, 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.”
“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.”
“Finally, our findings are very useful for understanding transmission of TB and infection spread, in general.”