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Developing a surveillance system to report TB in cattle herds exposed to badger control in England - SE3131

The aim of this project is to monitor bovine tuberculosis (bTB) incidence in cattle herds located within and just outside areas where badger control licenses will be issued (intervention areas) and compare to that of herds located within matched ‘comparison areas’, plus regional/national trends. As far as is possible within the design of the badger control policy, the purpose is to: a) monitor the effect of the intervention on bovine tuberculosis and b) identify important changes that could affect the badger control policy as early as possible. Given the pre-determined design of the control policy, this project will act as a surveillance activity rather than being hypothesis-driven research.

In the first year, badger control licenses will be granted by Natural England (NE) to two pilot areas, with up to ten further areas licensed in each of the following three years. As each new area is selected, NE will share boundary location data, enabling us to identify herds located in each intervention area and its 2km ‘buffer’ region.

We will first establish historical (three-years preceding intervention) bTB frequency measures in herds located within intervention areas so that changes over time can be assessed. Several bTB frequency measures will be analysed: e.g. number of new herd breakdowns per 100 herds tested, proportion of herds under movement restrictions due to a bTB breakdown etc.

Secondly, as bTB incidence may change over time for reasons unrelated to intervention, areas without intervention will be selected as comparison areas. Comparison areas most similar to intervention areas in features such as historical bTB incidence, cattle demography and geographical location will be selected. This is to reduce the risk that differences in incidence between intervention and comparison areas are due to factors other than badger control. However, it will not be possible to completely remove this risk or that of random variation and therefore cautious interpretation of study results will be required. Once comparison areas have been selected, reports will be compiled for each intervention: comparison couplet describing their historical bTB incidence and other features (e.g. cattle herd demography) that may influence the interpretation of future results.

Six-monthly and annual monitoring reports will examine different measures of bTB in cattle herds through simple descriptive statistics and graphs and more in-depth analyses where the effects of some factors (other than badger control) that could cause a difference between intervention and comparison areas, are adjusted for using regression techniques.

Any observable change in incidence resulting from the badger cull is likely to occur slowly over time and effects may not be observed in the early years of the study. However the effect of culling is anticipated to increase over time therefore the surveillance methods developed herein should be used for longer term monitoring.
Workpackage A – Couplet identification and characterisation
1. Develop a project protocol document
2. Establish baseline disease frequency data for cattle located in intervention areas
3. Identify areas with no badger control measures to serve as comparison areas to those with the intervention.

Workpackage B – Monitoring bTB incidence in cattle herds
1. Monitor measures of bTB incidence in cattle herds located in intervention areas relative to those in comparison areas.
Time-Scale and Cost
From: 2013

To: 2022

Cost: £342,898
Contractor / Funded Organisations
A H V L A (Animal Health and Veterinary Laboratories Agency - AHVLA)
Animal Diseases              
Animal Health              
Plants and Animals              
Fields of Study
Animal Health