NIMBioS Working Group: Feral swine / pseudo-rabies in Great Smoky Mountains National Park
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| (Back row, L to R): Joe Corn, Graham Hickling, Kurt VerCauteren, Chuck Collins; (Front, L to R): Suzanne Lenhart, Hamish McCallum, Marguerite Madden, René Salinas, Agricola Odoi, Ellen Kasari, Gary Smith, Seth Swafford. Not Pictured: Bill Stiver |
A Mad Itch: Controlling Pseudo-rabies in Feral Swine
Feral swine have been described as the most worrisome of non-native species in the Great Smoky Mountains National Park. These free-roaming pigs not only root out native plants and destroy natural habitats, but can also carry disease, such as pseudo-rabies, which is often fatal if transmitted to other wild and domestic animals.
With a goal to manage outbreaks of disease among wild animals in the Smokies as well as other natural areas, the Feral Swine/Pseudo-rabies Working Group at the National Institute for Mathematical and Biological Synthesis (NIMBioS) on the University of Tennessee, Knoxville, campus was initiated through a collaborative effort of mathematical and biological researchers at several academic institutions and wildlife managers at the park.
Current objectives for the Working Group, which holds its second meeting Jan. 25-26, 2010, include mathematical modeling of the feral hog population in the park, investigating prospects for predicting the spread of feral hogs in the southeastern United States, and reviewing the general principles of modeling and management of emerging diseases in feral species.
"What the Working Group is doing with modeling the problem is pretty interesting and useful in terms of showing the impact of hog control as well as showing what would happen if we did nothing to the population," said Bill Stiver, a wildlife biologist in the park and participant in the Working Group.
Despite its name, pseudo-rabies, also called "the mad itch," is not related to rabies and does not infect humans, but to wild canines, including coyotes and foxes, the disease is fatal, so wildlife managers want to ensure that they eliminate as many hogs as possible. In 2009, more than 600 hogs had to be removed from the park.
The Feral Swine/Pseudo-rabies Working Group
NIMBioS Working Groups are comprised of 10-15 invited participants and focus on specific questions related to mathematical biology. Each group typically meets two to three times over the course of two years at the Institute.
The National Institute for Mathematical and Biological Synthesis (NIMBioS) brings together researchers from around the world to collaborate across disciplinary boundaries to investigate solutions to basic and applied problems in the life sciences. NIMBioS is funded by the National Science Foundation in collaboration with the U.S. Department of Homeland Security and the U.S. Department of Agriculture, with additional support from The University of Tennessee, Knoxville.
NIMBioS Working Group: Feral swine / pseudo-rabies in Great Smoky Mountains National Park
Topic: Working Group on feral swine / pseudo-rabies in Great Smoky Mountains National Park
Meeting dates: April 27-29, 2009; January 25-26, 2010; August 10-12, 2010
Organizers: Graham Hickling (Department of Forestry, Wildlife and Fisheries, Institute of Agriculture, University of Tennessee, Knoxville; Director, Center for Wildlife Health); Suzanne Lenhart (Mathematics Department, University of Tennessee, Knoxville); Les Real (Biology Department, Emory University, Atlanta, Georgia)
Objectives: A theme of particular interest to NIMBioS’ sponsoring agencies is the enhancement of capacity to analyze and manage outbreaks of disease among wild animals and domestic herds. To address this theme, we are convening a Working Group on the problem of managing pseudo-rabies virus (PRV) and other disease agents among feral swine within Great Smoky Mountains National Park (GSMNP).
Feral swine have been managed in GSMNP for many years in response to the habitat damage they cause – they are now a focus of increased attention since the detection in 2005 of individuals infected with pseudo-rabies virus (PRV). Pseudo-rabies has almost certainly arrived in the Park as a consequence of hunters’ illegal releases of swine from quarantined states into either the Park or into the immediately adjacent National Forest land.
PRV is of great concern in North Carolina due to the large economic impact that would arise if swine exports from the State were quarantined as a consequence of spillover from feral swine from GSMNP. This situation provides a useful focus for our Working Group to address general issues of wildlife population management tied to spatial disease spread, and determining the optimal balance of effort between surveillance and control activities.
The Working Group’s aim is to develop a modeling approach that can incorporate what we know about feral pig movement, interaction and PRV transmission with what if scenarios relating to available management options (culling, fencing, vaccination of adjacent livestock) that Park managers could consider. Further, the modeling approaches adopted will aim to provide a sufficiently general framework to be a useful starting-point for similar problems in other parks and wildland areas in later years. Our intention is that the Working Group’s outputs be to the greatest extent possible transferable to other wildlife-livestock interface disease problems.
The extensive outreach opportunities to the general public provided by the National Park Service interpreters provide an opportunity to broaden public appreciation of the utility of these kinds of quantitative approaches in addressing issues of national concern related to natural system management. This Working Group also provides opportunities to strengthen connections with NIMBioS’ formal partners, particularly Oak Ridge National Laboratory, and Great Smoky Mountains National Park.
NIMBioS Working Group on Feral Swine/Pseudo-rabies in GSMNP:
Meeting 1 Summary, April 27-29, 2009
Participants: Charles Collins (Univ. of Tennessee); Joseph Corn (Univ. of Georgia); Kim DeLozier (Great Smoky Mountains National Park); Daniel Haydon (Univ. of Glasgow); Graham Hickling (Univ. of Tennessee); Ellen Kasari (USDA, APHIS, Veterinary Services); Suzanne Lenhart (Univ. of Tennessee); Edward Lungu (Ohio State Univ.); Hamish McCallum (Univ. of Tasmania); April McMillan (Oak Ridge National Laboratory); Agricola Odoi (Univ. of Tennessee); Les Real (Emory Univ.); René Salinas (Appalachian State Univ.); Bill Stiver (Great Smoky Mountains National Park); Kurt VerCauteren (USDA, APHIS, Wildlife Services)
This group is investigating optimal management of feral hogs in the GSMNP and the spread of pseudorabies in these hogs using control measures with spatial and temporal features. Recent data on hogs and pseudorabies in the GSMNP were discussed. The group then reviewed the growing distribution of feral hogs across the United States, as captured by the National Feral Swine Mapping system. Key tasks for the group were assigned, including:
- initiating modeling of the feral hog population in the GSMNP,
- investigating prospects for predicting the spread of feral hogs in the southeastern United States, and
- reviewing the general principles of modeling and management of emerging diseases in feral species.
NIMBioS Working Group on Feral Swine/Pseudo-rabies in GSMNP:
Meeting 2 Summary, January 25-26, 2010
Participants: Eric Carr (Univ. of Tennessee); Charles Collins (Univ. of Tennessee); Joseph Corn (Univ. of Georgia); Graham Hickling (Univ. of Tennessee); Ellen Kasari (USDA, APHIS, Veterinary Services); Suzanne Lenhart (Univ. of Tennessee); Marguerite Madden (Univ. of Georgia); Hamish McCallum (Griffith Univ.); Agricola Odoi (Univ. of Tennessee); René Salinas (Appalachian State Univ.); Gary Smith (Univ. of Pennsylvania); Bill Stiver (GSMNP); Seth Swafford (USDA Wildlife Services); Kurt VerCauteren (USDA Wildlife Services)
The second meeting began with an update on control efforts and disease surveillance of GSMNP hogs over the past year (Stiver). We then discussed the development and availability of geospatial datasets for the GSMNP (Madden) and a preliminary spatial model for population dynamics and movement of hogs within and adjacent to the park (Lenhart). Progress on nationwide mapping of feral hog distribution was reviewed (Corn). The University of Georgia has been developing a "cyber-infrastructure" proposal to the NSF for mapping and analysis of multiple invasive species, and our Working Group is collaborating on the feral hog component of that initiative.
A preliminary spatial model for the future spread of feral hogs in the southeastern U.S. was presented (Hickling, Collins and Carr), using Arkansas data as a case study to stimulate discussion on methodological approaches. The group then teleconferenced with Dr. Les Real to discuss opportunities for collaboration with RAPIDD (an NIH/DHS-sponsored disease modeling initiative, led by Bryan Grenfell). In March, RAPIDD is forming a working group to consider wildlife-livestock-human interface diseases, including several Foreign Animal Diseases spread by feral hogs.
Prospects for a review paper on the role of modeling in developing management strategies for control of disease in feral hogs were discussed (McCallum), and the significance of feral hogs within the USDA’s overall pseudorabies virus eradication and surveillance program was reviewed (Kasari/Swofford).
Key tasks: a preliminary set of tasks developed by the working group at its first meeting were reviewed and revised:
- Construct a non-spatial age-structured model representing the transmission of pseudorabies in a ‘generic’ feral hog population.
- Construct a spatial model that incorporates seasonal (vegetation-driven, terrain-driven, mast-related?) movement of hogs in GSMNP.
- Adapt an existing Individual Based Movement (IBM) bear model so that it can be applied to feral hogs.
- Spatial/GIS modeling aimed at predict hog distribution 2016 in two pairs of states:
- Arkansas/Missouri
- North Carolina/South Carolina - A Risk Analysis that will investigate overlaying Wildlife Services’ and SCWDS’ feral hog pseudorabies data on feral hog distribution data.
- A review article on the role of modeling in developing strategies for management of disease in feral hogs, including impacts on livestock and native biodiversity.
- A model of short-timescale disease spread in feral hogs, in eastern U.S. environment, using Classical Swine Fever data
NIMBioS Working Groups are chosen to focus on major scientific questions at the interface between biology and mathematics. NIMBioS is particularly interested in questions that integrate diverse fields, require synthesis at multiple scales, and/or make use of or require development of new mathematical/computational approaches. NIMBioS Working Groups are relatively small (10-12 participants, with a maximum of 15), focus on a well-defined topic, and have well-defined goals and metrics of success. Working Groups will typically meet 2-4 times over a two-year period, with each meeting lasting 3-5 days; however, the number of participants, number of meetings, and duration of each meeting is flexible, depending on the needs and goals of the Group.
