York research reveals new evidence for bovine TB debate
Posted on 29 April 2009
Through the novel use of electronic monitoring equipment researchers from University of York and the Scottish Agricultural College (SAC) have shown contacts between badgers and cattle are more frequent 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.
The belief that, out in the fields, badgers and cattle avoided each other means we may have been neglecting a potentially significant area of disease transmission between the species
Dr Mike Hutchings
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. It is recognised that the disease is firmly established in the badger population fuelling debate about which species spreads the disease and whether or not badgers should be culled.
A paper by Dr. Piran White of the University of York’s Environment Department and Dr Mike Hutchings of SAC’s Animal Health Research Group, published today in the journal PLoS ONE, describes how they fitted data loggers to badgers and cattle to monitor the frequency of meetings between the two species.
Their work, which involved research on a dairy farm and nearby woodland on the North York Moors, 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 scientists believe it is 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 not captured.
Dr Hutchings said: “Our work indicates that concentrating biosecurity measures on feed stores and cattle sheds which badgers are known to visit may not be enough.
The belief that, out in the fields, badgers and cattle avoided each other means we may have been neglecting a potentially significant area of disease transmission between the species.”
Another interesting finding 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 are 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.
Dr Hutchings added: “What was also surprising was that badgers contacted some cattle more frequently than they contacted other badgers from neighbouring social groups.”
Dr White says 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,” he added.
ENDS
Notes to editors:
- Mike Hutchings joined the Scottish Agricultural College in 1996 and is currently the Head of SAC’s Disease Systems Team. He held a Senior Research Fellowship from the then Scottish Executive Environment and Rural Affairs Department (SEERAD) between 2002 and 2007.
- Piran White was appointed as a Lecturer in the Environment Department in 1995. He was promoted to Senior Lecturer in 2000 and Reader in 2007. He has held visiting research posts at New South Wales Agriculture (Orange, Australia), AgResearch (Lincoln, New Zealand) and the University of Waikato (Hamilton, New Zealand). He is an Associate Editor of Journal of Animal Ecology, serves on the editorial board of the Australian journal Wildlife Research and is a member of the NERC Peer Review College.
- The paper “Contact Networks in a Wildlife-Livestock Host Community: Identifying High Risk Individuals in the Transmission of Bovine TB Among Badgers and Cattle” is published in PLoS One. Contact Rebecca Walton 01223 463333, rwalton@plos.org.
- Bovine TB arises from infection with Mycobacterium bovis bacteria. It is closely related to the Mycobacterisum tuberculosis that causes TB in humans but the risk of humans catching TB from cattle in Britain is considered very low. Bovine TB is transmitted between cattle, amongst badgers and between cattle and badgers.
- In July 2008 Secretary of State for the Environment, Food and Rural Affairs Hilary Benn announced he would not support a cull of badgers except in exceptional circumstances. He increased investment in vaccine research and established a TB Partnership Group with industry. The Minister has just announced a five year plan to vaccinate badgers against TB. Ministers in Wales favour a cull programme.
- This is not the first time that the authors have suggested the need for a systems approach to TB control in the UK. A systems approach would target control measures at a range of scales, from individual high risk animals to areas of the UK at risk of TB introduction and spread. Previously, Hutchings and White identified areas of the UK that would be considered as high risk of TB persistence and which may be targeted for increased TB surveillance to prevent spread.