Detection of Salmonella-specific antibody in swine oral fluids

Salmonella is a leading cause of bacterial foodborne-related illness and pork products are a food-associated source. With > 50% of U.S. swine herds testing positive for Salmonella, asymptomatic carrier pigs that shed Salmonella in their feces are a food safety and environmental contamination issue. Herd level surveillance of Salmonella shedding status is useful, but collection of feces and culture methods for Salmonella detection are laborious and time-consuming. Surveillance for Salmonella-exposure through detection of Salmonella-specific serum antibody is a reliable method, but presents labor and animal-welfare issues. Oral fluids are a reliable, antemortem sample with proven utility for surveillance in the swine industry. We tested oral fluid samples as a potential non-invasive, repeatable sample type for the presence of Salmonella-specific antibodies. An indirect enzyme-linked immunosorbent assay (ELISA) detected anti-Salmonella IgG, IgM, and predominantly IgA in oral fluids from Salmonella enterica serovar Typhimurium-exposed pigs. Furthermore, with minor modifications, a commercial ELISA-based kit also detected Salmonella-specific antibodies in oral fluids. Collectively, oral fluids may serve as a prospective surveillance tool for herd level monitoring of Salmonella exposure.