Development and testing of operational models of bovine tuberculosis in British cattle and badgers DEFRA

Development and testing of operational models of bovine tuberculosis in British cattle and badgers DEFRA

Issued: Tue, 25 Nov 2014 16:02:00 GMT


The bovine Tuberculosis modelling initiative brings together internationally recognised academic experts in the development and interpretation of mathematical and simulations models of bovine Tuberculosis (bTB) transmission and control in cattle and badgers. The aim of this consortium is to develop and test an operational modelling framework of bTB transmission and control. This project will be based on the best available evidence regarding the epidemiology of bTB, emphasizing robustness over complexity, so as to enhance the long term viability of the framework being developed.

For the purposes of this project, we define the following:
i) Operational: useable by appropriately trained and educated/experienced staff within the AHVLA, with capacity of further adaptation and refinement by the initiative core members or other appropriately qualified individuals or groups.
ii) Modelling framework: a set of interlinked, consistently developed modelling modules that can be robustly used for addressing various policy relevant questions, at various scales.
iii) Robust: scientifically sound and founded on well-tested and clearly described principles (epidemiological, mathematical, statistical, demographical and ecological, as appropriate)
The initial phases of this project will emphasize the development of the framework to consider cattle-based controls, including variation in testing schedules in order to reduce spread due to cattle and/or reduce testing burden. In order to ensure forward compatibility, a parallel stream of development of models to understand badger bTB infection dynamics will be undertaken, with the aim of future incorporation of approaches that consider both simultaneously.

The overall aim of this proposal is to develop an appropriate suite of predictive models (a “modelling framework”) for bTB transmission and control across multiple scales relevant to disease control in GB. Upon completion, this framework will primarily be used by AHVLA epidemiologists, to inform and support policy development and policy impact assessment. This aim has four underlying themes:

1. to integrate our understanding of existing models of bTB transmission in cattle and badgers, into a consistently parameterized framework, where these are appropriate to our objectives,
2. based on identified gaps in the available approaches, to develop new models where knowledge is sufficient,
3. to advise on the potential vulnerabilities in model prediction, including socio-economic and behavioural contexts, and
4. to advise on new research that may need to be commissioned, in order to fill gaps in knowledge and/or advise where modelling approaches may be inappropriate.

These tasks will be embedded in the development of the operational framework to inform policy development support by AHVLA staff. These models will be based on sound epidemiological modelling principles with an emphasis on scientific and technical robustness. The easiest route to informing policy would be a predictive model for the control of bTB with a high level of granularity that explicitly includes local information and explicit cattle and badgers at the individual-animal level.

Such an approach would have the advantage of being able to consider the full complexities of all likely disease control scenarios. While various models, both peer reviewed and in development or unpublished, incorporate some of these elements, to our knowledge, a robustly parameterised model including all these elements does not exist. Many data needed for such an approach are not available. Further, it is our view that even were perfect data to exist, a scientifically robust model of this type is likely to be beyond the scope of current approaches and therefore also beyond the remit of this group.

We note that as the demands on model outputs change (short term, medium term and long term predictability) appropriate caution will have to be exercised in the interpretation of outputs. In particular, longer term considerations of the extent and severity of the bTB epidemic can only be viewed as, at best, qualitative indicators, due to the uncertainties in the badger-cattle interaction, and the impact that human behaviour will have on the outcome.

Our specific Objectives include:

O.1. Development of within-herd model of bTB in cattle.
O.2 Development of between-herd models.
O.2.a. Historical models.
O.2.b. Predictive models.
O.3 Development of local badger models.
O.3.a Historical models.
O.3.b Predictive models.

[Source: DEFRA]

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