Classical Swine Fever and Food Security: Modeling the impact of trade restrictions on transboundary animal disease control in U.S. and Canadian swine

Abstract

Transboundary animal diseases (TADs) such as classical swine fever (CSF) are highly infectious animal diseases that have the potential to easily spread across international borders. TADs present a potential threat to food security and public health, often with severe economic consequences. CSF is a World Organisation for Animal Health notifiable disease that was eradicated from the U.S. in 1978 and Canada in 1963. Re-introduction could have a substantial economic impact and long-lasting repercussions on trade. Therefore, regulatory cooperation of TAD control between the United States Department of Agriculture and the Canadian Food Inspection Agency is one area of focus being explored to facilitate trade and economic growth, while mitigating the economic, public health, or social impacts of potential outbreaks. However, emergency response planning for a TAD outbreak in U.S. and Canadian swine populations has become challenging due to significant changes in the size, structure and connectivity of the swine industry in the last half-century. Epidemic simulation models are one type of tool that can be used to help understand the scope and impact of potential TAD outbreaks as well as evaluate the effectiveness of disease control strategies. This thesis outlines the incremental development of a spatially-explicit, stochastic transboundary epidemic simulation model of CSF between U.S. and Canadian swine farms to examine the epidemiological impact of international trade restrictions following CSF detection and evaluate the use of mutually recognized zones for disease control. Individual animal and herd-level disease parameters (latent, subclinical, incubation and clinical periods) for highly and moderately virulent CSF are developed in Chapter 2. A transboundary model of CSF is developed in Chapter 3 to evaluate the scope and scale of potential CSF outbreaks while varying the index farm location (Iowa, North Carolina, Ontario or Quebec), production type (farrow-to-wean or nursery operation) and CSF virulence level (high or moderate virulence CSF). The transboundary model is used in Chapter 4 to evaluate epidemiologic outcomes of different control policies for swine movements at the U.S. and Canadian border.