ABC [almost] in the front news

cow (with TB?) on one of the ghats, Varanasi, Uttar Pradesh, Jan. 6, 2013My friend and Warwick colleague Gareth Roberts just published a paper in Nature with Ellen Brooks-Pollock and Matt Keeling from the University of Warwick on the modelling of bovine tuberculosis dynamics in Britain and on the impact of control measures. The data comes from the Cattle Tracing System and the VetNet national testing database. The mathematical model is based on a stochastic process and its six parameters are estimated by sequential ABC (SMC-ABC). The summary statistics chosen in the model are the number of infected farms per county per year and the number of reactors (cattle failing a test) per county per year.

“Therefore, we predict that control of local badger populations and hence control of environmental transmission will have a relatively limited effect on all measures of bovine TB incidence.”

This advanced modelling of a comprehensive dataset on TB in Britain quickly got into a high profile as it addresses the highly controversial (not to say plain stupid) culling of badgers (who also carry TB) advocated by the government. The study concludes that “only generic measures such as more national testing, whole herd culling or vaccination that affect all routes of transmission are effective at controlling the spread of bovine TB.” While the elimination of badgers from the English countryside would have a limited effect.  Good news for badgers! And the Badger Trust. Unsurprisingly, the study was immediately rejected by the UK farming minister! Not only does he object to the herd culling solution for economic reasons, but he “cannot accept the paper’s findings”. Maybe he does not like ABC… More seriously, the media oversimplified the findings of the study, “as usual”, with e.g. The Guardian headline of “tuberculosis threat requires mass cull of cattle”.

3 Responses to “ABC [almost] in the front news”

  1. abhay abhyankar Says:

    Might it not be a good idea to study the counterfactual.TB in cows in countries without badgers or area where badgers do not exist in close proximity to farms – Switzerland,Spain the USA? what is the prevalence of bovine TB there and how is it transmitted in such an environment.

    • The problem with the counterfactual is that the other factors contributing or preventing TB differ from one country to another, from cattle populations to cattle management, to wildlife prevalence… For instance, there are about twice as many badgers in Britain than in France, but that does not make the two countries particularly comparable (with hardly any TB in France).

  2. Somebody I know familiar with the many studies down through the years made the comment that until the reward system changes for farmers that TB will continue to be a problem and they will continue to blame badgers who are relatively blameless in the whole affair. There is amost no penalty (relatively speaking) for farmers whose herds get TB and until that changes they will continue to use unsafe farming methods – and that was a comment made long before these recent studies came out.

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