SREL Reprint #3693

Optimising response to an introduction of African swine fever in wild pigs

Kim M. Pepin1, Vienna R. Brown2, Anni Yang1,3, James C. Beasley4, Raoul Boughton5,
Kurt C. VerCauteren1, Ryan S. Miller6, and Sarah N. Bevins1

1National Wildlife Research Center, Wildlife Services, Animal and Plant Health Inspection Service,
United States Department of Agriculture, Fort Collins, Colorado, USA
2United States Department of Agriculture, Animal and Plant Health Inspection Services,
Wildlife Services, National Feral Swine Damage Management Program, Fort Collins, Colorado, USA
3Department of Fish, Wildlife, and Conservation Biology, Colorado State University,
Fort Collins, Colorado, USA
4Savannah River Ecology Laboratory, Warnell School of Forestry and Natural Resources,
University of Georgia, Aiken, South Carolina, USA
5Buck Island Ranch, Archbold Biological Station, Lake Placid, Florida, USA
6Centers for Epidemiology and Animal Health, Veterinary Services, Animal and Plant Health
Inspection Service, United States Department of Agriculture, Fort Collins, Colorado, USA

Abstract: African swine fever virus (ASFv) is a virulent pathogen that threatens domestic swine industries globally and persists in wild boar populations in some countries. Persistence in wild boar can challenge elimination and prevent disease-free status, making it necessary to address wild swine in proactive response plans. In the United States, invasive wild pigs are abundant and found across a wide range of ecological conditions that could drive different epidemiological dynamics among populations. Information on the size of the control areas required to rapidly eliminate the ASFv in wild pigs and how this area should change with management constraints and local ecology is needed to optimize response planning. We developed a spatially explicit disease transmission model contrasting wild pigmovement and contact ecology in two ecosystems in Southeastern United States. We simulated ASFv spread and determined the optimal response area (reported as the radius of a circle) for eliminating ASFv rapidly over a range of detection times (when ASFv was detected relative to the true date of introduction), culling capacities (proportion of wild pigs in the culling zone removed weekly) and wild pig densities. Large radii for response areas (14 km) were needed under most conditions but could be shortened with early detection (≤8 weeks) and high culling capacities (≥15% weekly). Under most conditions, the ASFv was eliminated in less than 22 weeks using optimal control radii, although ecological conditions with high rates of wild pig movement required higher culling capacities (≥10% weekly) for elimination within 1 year. The results highlight the importance of adjusting response plans based on local ecology and show that wild pig movement is a better predictor of the optimal response area than the number of ASFv cases early in the outbreak trajectory. Our framework provides a tool for determining optimal control plans in different areas, guiding expectations of response impacts, and planning resources needed for rapid elimination.

Keywords: African swine fever, culling, outbreak response, spatially explicit, transmission model, wild pigs

SREL Reprint #3693

Pepin, K. M., V. R. Brown, A. Yang, J. C. Beasley, R. Boughton, K. C. VerCauteren, R. S. Miller, and S. N. Bevins. 2022. Optimising response to an introduction of African swine fever in wild pigs. Transboundary and Emerging Diseases 69(5): e3111-e3127.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).