Exploration of factors that might explain the spread of the bovine TB endemic area : a report for AHVLA

Abstract

The aim of this project was to explore the recent spread of bovine TB, to try to identify factors that are important in the expansion of infected areas since re-emergence of the disease in the 1980s.

We used various visualisation techniques, including mapping, to examine the changing distribution of the disease and identify where areas of higher prevalence appear to be expanding generally outwards from an area of persistently high prevalence. These expansion areas were visualised and characterised in terms of ‘fronts’. We developed a method for formally (mathematically) identifying and describing the fronts. We then looked for correlations between front characteristics (e.g. velocity) and local conditions, to see if we could explain what was driving expansion in these areas. Early in the project, we agreed with AHVLA to restrict consideration of data to 2002 onwards. This was to avoid including the period during and immediately following the 2001 foot-and-mouth disease outbreak in Britain, which would complicate analysis and because this would be more relevant to understanding the current situation.