Host range overlap among pathogens of free-ranging swine, other wild and farmed species, and humans – implications for risk management of feral swine in North America

Estimating the risk of disease spread from free-ranging (feral) swine (Sus scrofa) to livestock, wildlife and people is a key objective of the USDA APHIS National Feral Swine Damage Management Program. To address this issue,... [ view full abstract ]

Estimating the risk of disease spread from free-ranging (feral) swine (Sus scrofa) to livestock, wildlife and people is a key objective of the USDA APHIS National Feral Swine Damage Management Program. To address this issue, we used a structured literature review to evaluate the status of known pathogens of swine and their coexistence in other host species groups in North America. Further, we illustrated the economic importance of managing disease risks in feral swine by estimating the number of farms and rural populations in the United States potentially at risk of feral swine contact and by examining agricultural export values following animal disease outbreaks in other countries. We identified 34 known swine pathogens that cause clinical disease in livestock, poultry, North American cervids, and humans. On average, swine shared 73% of bacterial, 39% of viral, and 63% of parasitic pathogens with other species groups. Bovids (cattle, sheep, and goats) had the most pathogens (82%) in common with swine. Only 45% of reportable domestic swine pathogens had published surveillance studies for wild swine. Investigation of economic impacts found a median export decline of 18% after a reportable animal disease outbreak that translated to USD $2.8 billion in U.S. agricultural exports. The co-occurrence of wild swine and farms increased at an annual mean rate of 1.2% with as much as 57% of all farms and 77% of all agricultural animals residing in counties with wild swine. Our risk assessment identified significant gaps in knowledge required to inform surveillance, risk assessments, scientific studies, and risk mitigations for diseases of free-ranging swine in the United States.