How to cite this article: Vet. Res. (2009) 40:18
DOI: 10.1051/vetres:2009001

The impact of seasonal variability in wildlife populations on the predicted spread of foot and mouth disease

Linda D. Highfield¹, Michael P. Ward^{1, 2}, Shawn W. Laffan³, Bo Norby¹ and Gale Wagner<sup>4

1</sup>  Department of Veterinary Integrative Biosciences, Texas A&M University College of Veterinary Medicine & Biomedical Sciences, College Station, TX 77845-4458, USA
²  Current address: Faculty of Veterinary Science, The University of Sydney, Private Mail Bag 3, Camden NSW 2570, Australia
³  School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
⁴  Department of Veterinary Pathobiology, Texas A&M University College of Veterinary Medicine & Biomedical Sciences, College Station, TX 77845-4458, USA

Received 8 August 2008; accepted 9 January 2009; published online 13 January 2009

Abstract - Modeling potential disease spread in wildlife populations is important for predicting, responding to and recovering from a foreign animal disease incursion such as foot and mouth disease (FMD). We conducted a series of simulation experiments to determine how seasonal estimates of the spatial distribution of white-tailed deer impact the predicted magnitude and distribution of potential FMD outbreaks. Outbreaks were simulated in a study area comprising two distinct ecoregions in South Texas, USA, using a susceptible-latent-infectious-resistant geographic automata model (Sirca). Seasonal deer distributions were estimated by spatial autoregressive lag models and the normalized difference vegetation index. Significant (P < 0.0001) differences in both the median predicted number of deer infected and number of herds infected were found both between seasons and between ecoregions. Larger outbreaks occurred in winter within the higher deer-density ecoregion, whereas larger outbreaks occurred in summer and fall within the lower deer-density ecoregion. Results of this simulation study suggest that the outcome of an FMD incursion in a population of wildlife would depend on the density of the population infected and when during the year the incursion occurs. It is likely that such effects would be seen for FMD incursions in other regions and countries, and for other diseases, in cases in which a potential wildlife reservoir exists. Study findings indicate that the design of a mitigation strategy needs to take into account population and seasonal characteristics.

Key words: spatial modeling / epidemic modeling / foot and mouth disease / wildlife

Corresponding author: m.ward@usyd.edu.au

© INRA, EDP Sciences 2009