As humans have moved cattle around the world, bovine tuberculosis has also spread. It now has a global distribution and is especially problematic in Africa, where it was introduced by European livestock in the 1800s. The disease infects vital wildlife populations, such as buffalo and lions in Kruger National Park in South Africa, where tourism is an integral part of local economies.

In Ireland and the UK it infects cattle and the wildlife badgers (Meles meles) and the latter have been implicated in the spread of the disease in cattle. To understand how the disease spreads and to inform control policy, we determine here the joint spatial pattern in cattle and badgers. Previous work (1,2) has established that TB spatially clusters in badgers and separately in cattle. Here we look at spatial clustering across the species. The analysis involves fitting linear geostatistical models (LGM's) with exponential covariance structure, adjusting where necessary for anisotropy.

The results have implications for control policy suggesting that a single scale for badger culling either proactive or reactive may not be appropriate. Present Irish policy that examines TB outbreaks in cattle herds on a case-by-case basis seems justified.

References:

1. Kelly GE, McGrath GE, More SJ. Estimating the extent of spatial association of Mycobacterium bovis infection in badgers in Ireland. Epidemiology and Infection 2010, 38:270-279.

2. Kelly GE, More SJ. Spatial association of bovine TB in cattle herds prior to and during proactive badger removal. Epidemiology and Infection 2010, In press.

Keywords: Spatial models; Bovine TB; Badger; Disease control

Biography: Gabrielle Kelly received a Ph.D. in Statistics from Stanford University in 1981. Since then she has held positions in statistics in University Collge Cork, Columbia University and University College London and Middlesex School of Medicine. She joined University College Dublin (UCD) in 1990 where she is presently a senior lecturer in statistics in the School of Mathematical Sciences. Her interests include veterinary epidemiology and she has worked in collaboration with the the Centre for Veterinary Epidemiology and Risk Analysis in UCD since 2000, in the design and analysis of experiments and observational studies in relation to bovine TB. She is presently engaged in the application of spatial models to data from such studies. She has supervised several Ph.D. and Masters students in this area. She served as the statistician on the Animal Research Ethics Committee in UCD for several years.