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An exploration of factors that influence the expansion of the area affected by endemic bTB - SE3045

Although pre-movement testing for bTB has had a significant impact on the long distance spread of the disease, especially on transmission to areas with relatively low incidence (Mitchell et al. 2008, Defra 2010), the role of local spread in the expansion of bTB-affected areas is not well understood. Despite the net annual benefit of pre-movement testing for bTB being predicted to reach tens of millions of pounds by 2015, illustrating the benefits achievable by controlling risk factors, the predicted long term trend is for bTB to continue to increase its geographical extent in England and Wales (Defra 2010).
This proposal will further investigate and quantify known factors that are associated with local bTB spread, and also develop novel theories on other factors. The project will (through an integrated multidisciplinary approach) use a mixture of existing comprehensive datasets, such as Cattle Tracing System, VetNet, VeBus and land-use maps, and also gather new data and information from industry representatives through workshops and surveys.
To establish how far and fast areas of endemic bTB are spreading, the primary step will be to develop a robust measure of exactly what is meant by endemic status. Endemic not only denotes a high prevalence of disease but also requires the disease to persist in cattle populations (and the associated wildlife). We shall establish an operational mathematical measure of endemicity based on surveillance results, taking into account changes in bTB surveillance activities, and apply it to data from the last ten years. Knowing the genotype of the bacterium causing bTB will help distinguish overlapping endemic areas. The areas affected by endemic bTB at regular time points will then be mapped and measured for speed of expansion.
Once the locations of endemic bTB areas and their rates of expansion are defined, the risk factors aiding spread (including geographical features and farm management practices where the expansion is occurring) will be investigated. There is a substantial body of literature on risk factors for bTB herd breakdown and spread. To maximise the use of this previous work we shall mine the literature for factors that have been demonstrated to have a significant impact on bTB spread (e.g. cattle movements) and for other potential factors, and investigate the influence of these factors on the speed of bTB spread. Hypothesising that different risk factors will operate in areas depending on local infection pressure and farming contexts; we will explore risk factors for TB in the context of disease endemicity.
As part of the project, an interdisciplinary social research component will iteratively identify relevant farm practices that may act as risk factors in the spread of endemic bTB. It will involve intensive social research with farmers in areas vulnerable to the spread of endemic bTB leading to the identification of social risk factors that will be incorporated within a subsequent survey. Crucially, the social work package will draw on observation as well as traditional oral forms of research (e.g. interviews and focus groups) to identify relevant farm practices. It will also involve farmers and other participants (e.g. vets) in meaningful ways, for example through the identification and agreement of risk factors.
Objective A1:
Mapping the expansion of defined endemic fronts in England and Wales
• To identify and validate a meaningful and generally applicable mathematical method for detecting the endemic status of bTB in cattle for given places and times, and to use the method to map the expansion of the area affected by endemic bTB through time.

Objective A2:
Evaluating risk factors that affect the rate of expansion of endemic areas
• To analyse the relationship between the rate of expansion of endemic areas and locally coexistent bTB risk factors.

Objective B1:
Exploring Farm Practices and Risk Factors on the edge of endemic areas
• To iteratively identify relevant farm practices that may act as risk factors in the spread of endemic bTB.

Objective B2:
The incorporation of social research data on bTB spread into the epidemiological analysis
• The incorporation of social research data on bTB spread into the epidemiological analysis

Objective C:
Project Management
• To manage the project to Prince 2 principles including establishing a project board, communication plans, project reports and logistical activities related to other work packages.
Time-Scale and Cost
From: 2012

To: 2015

Cost: £602,910
Contractor / Funded Organisations
Veterinary Laboratories Agency (VLA)
Animal Diseases              
Animal Health              
Plants and Animals              
Fields of Study
Animal Health