TB survey to spotlight risks
By Emma Penny
A SURVEY of cattle producers should help researchers identify why some farms suffer TB and others in the same area remain free of the disease.
The survey, involving the Vet Lab Agency in Weybridge, Surrey, and the Central Science Lab, York, aims to identify management factors influencing TB incidence on farm.
According to Richard Clifton-Hadley, senior vet research officer at Weybridge, the Milk Development Council-funded survey, which is completely confidential, should show whether there are steps cattle producers can take to cut risk of TB infection.
"We were aware that there has not been much information gathered about the risks influencing infection.
"Also, there are now cases of TB where we would not have expected them before, such as Staffordshire. This might be tied into an increasing badger population, but it might also be due to an increasing infection level in badgers; since the road traffic accident survey stopped, we have not had such detailed information on infection levels in badgers."
But he says that TB may be spread by other animals. Wild deer are known to carry it, while it is thought that some management practices can also help spread TB.
"This survey should help identify any factors contributing to a TB breakdown, and we hope that it will provide practical advice to help reduce the risks.
"In the past, people have perhaps shied away from farm management as most factors cutting risks are not going to reduce it by a big percentage." But he says that a combination of management factors may help cut transmission risks, and this is what the survey aims to identify.
"Climate may also have an effect, particularly as most concerns have centred on south-west England and Ireland. But farmers cannot do anything about the weather, making concentrating on small, but cumulatively important factors vital."
The survey is likely to be posted to producers in early July, depending on final approval from the governments statistics office, says Weybridge-based vet officer Kathy Christiansen.
"We are targeting farms that had a break-down in 1997/98, which should give us about 500 herds. We will also be selecting two farms in the same area which have not had a TB breakdown and tested clear in 1998.
"TB-free farms selected for the survey will be those exposed to the same risk as those which have had break-downs. Working with a hypothesis that badgers are the main source, we want farms which are clear of TB but yet cattle have had the same opportunity to meet badgers.
"We know that we are less likely to get a response from those producers who have not suffered a break-down on-farm, but we need their responses. The higher the response rate, the greater the chance of identifying factors which can help cut risks," she says.
The survey is centred on herd management. Grazing management, farm boundary type, access to woodland, slurry management, housing, feed management and wildlife on-farm will be covered, says Dr Clifton-Hadley.
"Questions are based round MAFFs new TB 99 form, which is used to help identify the cause of break-downs. However, the survey will be a much simpler form, based on ticking boxes, and will be tested with MDC members to ensure it is user-friendly."
Answers will be closely analysed with any relationships between management factors identified, says Dr Christiansen.
"We hope to report to the MDC in March 2000, giving practical advice on reducing risk of infection. We may find that badgers are the reservoir of infection, but it is how it is transmitted, that is the problem." *
• Identify management factors.
• Produce guidelines.
• Good response vital.