Hierarchical models for the spatio-temporal dynamics in*
Principal Investigator: Gary Smith
Affiliation: University of Pennsylvania
Abstract: We shall develop an evidence-based hierarchical family of paradigmatic model frameworks for the temporal and spatial spread of two directly transmitted infections of farm animals: Avian Influenza (Al) and Foot and Mouth Disease(FMD. With respect to modeling disease systems we shall create both local (within herd/flock), county, state and national models of Al and FMD. The heirarchical strategy is important because the simpler models can be completed more quickly and parameterized more readily and are therefore more likely to be available for use than the more complicated models. Their behavior can more easily be generalized to other systems and can inform response measures in a strategic (if not tactical) sense. The more complicated models are essential tactical instruments but will take longer to complete and their behavior may not be so easily generalized to other infections. Our proposal represents a compromise between the need to provide useful strategic information about a range of potential threats - and the requirement that we can inform tactical decisions about prevention, response and recovery. Among other things, we shall investigate the appropriate level of granularity (scale) for each of these models. There are few regions in the USA where farms locations are mapped to level of detail required for most existing types of models for spatial and temporal spread at state or national scales. We shall devise models (metapopulation/ Patch/ Gravity models) based on other spatial resolutions (eg data based on zip codes, counties, or a national grid system). We shall test and calibrate these approximations using detailed spatial stochastic models developed using detailed and extensive GIS data bases on farm location in Pennsylvania and then extend their use to other regions in the USA. We shall use the models to devise and refine strategies for prevention, response and recovery. Avian Influenza and Foot and Mouth Disease are potential agents of bio/agroterrorism in addition to being devastating animal epidemic diseases in their own right which have have dramatic adverse effects on the well-being (social, economic and psycholgical) of human populations. The models proposed here will assist in planning strategies for prevention, control and response. In the case of Avian Influenza especially, controlling the infection in birds is a pre-emptive strategy for control in people.
Funding Period: 2006-02-01 - 2009-01-31
more information: NIH RePORT
- Models of highly pathogenic avian influenza epidemics in commercial poultry flocks in Nigeria and GhanaSky T K Pelletier
School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348, USA
Trop Anim Health Prod 44:1681-7. 2012..That this did not happen was most probably a result of the very swift Ghanaian response to news of the first introductions...
- Food- and water-borne disease: using case control studies to estimate the force of infection that accounts for primary, sporadic casesG Smith
School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348, United States
Epidemics 5:77-84. 2013..The paper finishes with a worked example using one of the most common of all food- and water-borne pathogens, Toxoplasma gondii...
- Is R(0) a good predictor of final epidemic size: foot-and-mouth disease in the UKMichael J Tildesley
Centre for Infectious Diseases, Institute of Immunology and Infection Research, University of Edinburgh, Ashworth Labs, West Mains Road, Edinburgh EH9 3JT, UK
J Theor Biol 258:623-9. 2009..Combining these two predictions provides a good assessment of both the local and larger-scale heterogeneities present in this complex system...
- The role of pre-emptive culling in the control of foot-and-mouth diseaseMichael J Tildesley
Centre for Infectious Diseases, University of Edinburgh, Ashworth Laboratories, Kings Buildings, Edinburgh EH9 3JT, UK
Proc Biol Sci 276:3239-48. 2009....
- Estimating the kernel parameters of premises-based stochastic models of farmed animal infectious disease epidemics using limited, incomplete, or ongoing dataChris Rorres
Section of Epidemiology and Public Health, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA
Theor Popul Biol 78:46-53. 2010..Target epidemics were simulated with the model and the three estimators were implemented using various combinations of collected data to independently determine the two parameters...
- Ongoing estimation of the epidemic parameters of a stochastic, spatial, discrete-time model for a 1983-84 avian influenza epidemicC Rorres
School of Veterinary Medicine, University of Pennsylvania, 382 West Street Road, Kennett Square, PA 19348, USA
Avian Dis 55:35-42. 2011..These data are then jackknifed on a progressive weekly basis to show how our estimates can be applied to an ongoing epidemic to generate continually improving values of certain epidemic parameters...
- Stochastic modeling of animal epidemics using data collected over three different spatial scalesChris Rorres
School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA
Epidemics 3:61-70. 2011..Such analyses of data collected on different spatial scales are useful in formulating intervention strategies to control an ongoing epidemic (e.g., vaccination schedules and culling policies)...
- How backyard poultry flocks influence the effort required to curtail avian influenza epidemics in commercial poultry flocksG Smith
School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, Kennett Square, PA 19348, USA
Epidemics 3:71-5. 2011..g. commercial flocks only) necessarily underestimate the level of effort to an extent that may matter to policy makers...