Antimicrobial Use, Resistance and Residues

Genomic Sequencing of STEC Isolates From Feral Pigs and Outdoor-Raised Pigs in High-Risk Contact Areas in California

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Abstract

Although a majority of American swine production occurs inside confinement buildings, the US is currently experiencing a resurgence of outdoor-based (i.e., pasture-raised) pig operations, due to growing consumer demand for sustainably-produced foods, including humanely-raised meat. A challenge in raising pigs outdoors is the increased risk of domestic pigs interfacing with wildlife, like feral pigs. California has one of the largest and widest distributions of feral pig populations, which continues to expand. While still primarily considered a niche market, outdoor-raised pig operations (OPO) are numerous in CA, providing an opportunity for the widespread transmission of diseases throughout the state, as each pig could serve as a link in the spread of pathogens between wildlife, livestock and humans. Both domestic and feral pigs are asymptomatic reservoirs for zoonotic and foodborne pathogens. For instance, feral pigs were implicated in the 2006 nationwide E. coli O157:H7 outbreak in spinach. Several studies have identified feral pigs in CA as carriers of E. coli O157:H7, with prevalence ranging from 3.6% to 14.9%. A recent CA study found a prevalence of 5.6% Shiga toxin-producing Escherichia coli (STEC), with a range per farm of 0-25%, in pigs raised outdoors on small-scale farms, including serogroups, which are on the CDC’s list of top seven STEC of public health concern. These two parallel trends of an expanding feral pig population and an increase in OPO, create a potential risk for zoonotic diseases exposure and transmission, which could negatively impact both public and livestock health, and agricultural economy. The objective of this study was to characterize STEC isolates from fecal samples from outdoor-raised pigs and feral pigs collected in a cross-sectional study and use shotgun whole genome sequencing (WGS) to assess the relatedness of strains between domestic outdoor-raised pigs living near feral pig habitats in high-risk areas of interface in California.

How to Cite:

Patterson, L., Basbas, C., Pereira, R. V., Chandler, C., Haghani, V., Ramos, T. D., DiCaprio, E., Martínez-López, B. & Pires, A. F., (2023) “Genomic Sequencing of STEC Isolates From Feral Pigs and Outdoor-Raised Pigs in High-Risk Contact Areas in California”, SafePork 14(1). doi: https://doi.org/10.31274/safepork.16324