When Badgers Meet Cows - New Evidence for Bovine TB Debate
2009-04-29

Ground-breaking new research gives a much deeper insight into how TB could be passed from badgers to cattle and back again.

New opportunities for controlling TB in cattle

Through the novel use of electronic monitoring equipment, researchers from SAC and University of York have proved contacts between badgers and cattle happen more often than previously thought. It offers new opportunities for controlling a disease that has ravaged herds in the south and west of England and is costing tax payers £100m a year for testing and compensation to farmers.

TB, which had been virtually eradicated in British cattle, began to re-emerge among dairy herds in the south west of England during the 1990’s. A control programme was hampered by the FMD outbreak in 2001 which diverted veterinary effort. It is recognised that the disease is firmly established in the badger population, fuelling fierce debate about which species spreads the disease and whether the badgers should be culled.

Published today in the Journal PLoS ONE is a paper by Dr Mike Hutchings of SAC’s Animal Health Research Group and Dr. Piran White of the University of York’s Environment Department, who describe how they fitted data loggers to badgers and cattle that record close proximity and used them to monitor meetings among badgers and cattle. Their work represents the first continuous time record of wildlife-host contacts for any free living wildlife-livestock disease system. Previous work had relied heavily on visual observations.

While there is still uncertainty surrounding the way TB is transmitted, one of the ways is it is believed to be spread is via the breath of infected animals. The significance of this new research lies in the recording of close contacts between badgers and cattle at pasture, something previous visual observation had failed to notice.

“Our work indicates that concentrating biosecurity measures on feed stores and cattle sheds which badgers are known to visit may not be enough” says Dr Mike Hutchings. "The belief that, out in the fields, badgers and cattle avoided each other means we have been neglecting a potentially significant area of disease transmission between the species."

Adding to the significance of the research is data suggesting that some cattle are more curious and sociable than others. Not only are these individuals more likely to be curious about badgers, but they also mix more readily with other cattle and are therefore, potentially, more likely to catch and then pass on any infection. It is already known that cows with a higher status in the herd tend to catch TB. This work provides evidence to explain why this may be the case and highlights the role that direct contacts with badgers may play in the process.

“What was also surprising was that badgers contacted some cattle more frequently than they contacted other badgers from neighbouring social groups” added Dr. Hutchings.

He and his research colleague Piran White believe this new work suggests new opportunities for tackling a disease that has become a major social and economic issue, as well as an animal health and welfare problem.

“Policy is currently against culling so we need ways to reduce disease transmission. This study presents one potential avenue to achieve this, through targeting specific, high risk animals” says Dr White.

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