ECOLOGY AND EPIDEMIOLOGY OF E. COLI O157:H7 IN FRESH PRODUCE PRODUCTION REGIONS ON THE CENTRAL CALIFORNIA COAST

We hypothesize that key biotic and abiotic processes link primary environmental reservoirs of E. coli O157 with fields of Leafy Vegatables (LV) located in the largest U.S. producing region for LVs. The specific hypotheses and research objectives of the proposed research are that vertebrate populations (e.g., cattle and wild pigs) located in the interior of the Central California Coast (CCAC) function as the key source of EcO157 contamination of LV either through direct fecal deposition in LV fields or indirectly via fecal contamination of adjoining watersheds draining into and alongside the fields used for LV production. We propose to quantify environmental loading by vertebrate sources (especially cattle and wild pigs) that may function as key sources of EcO157 contamination of LV directly through fecal deposits, or indirectly, via fecal contamination of watersheds, wells or soil in contact with LV row crop fields; to create a molecular subtyping database of EcO157 strains in the CCAC to characterize the genetic relatedness of environmental and outbreak-associated isolates; to determine if increased commensal E. coli concentration and presence of shigatoxin-producing E. coli strains are associated with fecal contamination and an increased risk of EcO157 contamination in LV production areas; and to develop and disseminate educational materials for growers of fresh produce regarding specific strategies to prevent pre-harvest microbial contamination; to educate the livestock community about microbial water quality, potential impacts on down-stream stakeholders, wildlife management strategies, and effective BMPs for improving water quality.