Updated projections for risk-based surveillance for bovine tuberculosis for low risk areas in England and Wales

In recent work, a research group led by Prof. Kao identified risk-based surveillance strategies for bovine Tuberculosis (bTB) in Scotland, using a combination of statistical models and a simulation model for freedom from infection, to identify a series of possible strategies to reduce the number of regular herd tests for bTB in Scotland. In a subsequent work on risk-based surveillance (also led by Prof. Kao) (Defra project SE3285), it was shown that that there are opportunities to improve the current surveillance system in areas of low risk of bTB (LRAs). The current proposal will build on previous work to determine if alternative surveillance strategies can improve the current surveillance system by looking at the most recent epidemiological situation in these areas. Different strategies will be considered, contingent on discussion with Defra and APHA colleagues. Broadly speaking reduction strategies can follow several strands: i) Reduction in testing - direct reduction of the amount of testing done, as a strategy aimed at directly reducing costs. Ideally, this will be a 'dominant' strategy, whereby testing is reduced but with minimal risk of an increase in incidence of breakdowns. This strategy would be most similar to the recommendations for Scotland. ii) Onward risk reduction - this aims partly to identify herd breakdowns more quickly by targeting herds that are at a higher risk of infection. iii) Reduction in testing and onward risk – directly reduction of the amount of testing done while identifying herd breakdowns more quickly. We shall adopt a three-step approach to this project, using methodologies and analyses based on existing work, either published or currently undergoing scientific peer review. A). Develop statistical models to identify risk factors for breakdowns within LRAs. B). Define risk-based surveillance strategies based on combinations of the criteria (i) to (iii). C). Based on the best, analytically sound recommendations using A and B we shall consult with Defra and APHA colleagues to determine their feasibility. We shall therefore provide an analysis of the current risk situation in LRAs where the two aims of testing reduction and reduced onward risk will be balanced against the practicality of implementation and relevance to policy requirements.