An all-island approach to mapping bovine tuberculosis in Ireland

Abstract

This study used techniques in Geographical Information Systems (GIS) to explore the spatial patterns of bovine tuberculosis (TB) in the whole island of Ireland over an 11-year period. This is the first time that data pertaining to TB from the Republic of Ireland and Northern Ireland have been collated and examined in an all-Ireland context. The analyses were based on 198, 156 point locations representing active farms with cattle in Northern Ireland and the Republic of Ireland between the years 1996 and 2006. The results consist of a series of maps giving a visual representation of cattle populations and associated detected bTB levels on the island of Ireland over this time interval.

Figure 1

Density map of the TB-tested cattle population each year on the island of Ireland for the years 1996 to 2006.

Figure 2

Density map of TB standard reactors detected each year on the island of Ireland for the years 1996 to 2006.

Figure 3

Density map of animal-level TB risk each year on the island of Ireland during 1996 to 2006. Animal-level TB risk was calculated each year as a relative risk surface after overlaying the density map of TB standard reactors over the density map of cattle population tested for TB.

Figure 4

Thematic map of the TB-tested cattle population each year on the island of Ireland from 1996 to 2006. Cattle population data from each farm were assigned to the relevant hexagon, based on the location of its point representation.

Figure 5

Thematic map of TB standard reactors detected each year on the island of Ireland from 1996 to 2006. TB reactor data from each farm were assigned to the relevant hexagon, based on the location of its point representation.

Figure 6

Thematic map of animal-level TB risk each year on the island of Ireland from 1996 to 2006. Animal-level TB risk was calculated each year after dividing the summarised disease data with the summarised population data in each hexagon and expressed as a percentile.