ECOLOGY AND EPIDEMIOLOGY OF ESCHERICHIA COLI O157:H7 IN FRESH PRODUCE PRODUCTION REGIONS OF SALINAS, CALIFORNIA

It is hypothesized that vertebrate populations function as a key source of E. coli O157:H7 (EcO157) contamination of watersheds where lettuce and other leafy vegetables are grown; that climate, landscape attributes, and irrigation practices correlate with increased risks of EcO157 and commensal E. coli contamination; and in-field contamination of lettuce plants with EcO157 relates to combinations of production practices and environmental risk factors in the Salinas Valley. The major objectives of this project are the design of a sampling strategy and to sample the environment of leafy vegetable production to (1) quantify environmental loading by vertebrate sources, (2) characterize predisposing conditions for hydrological transport of EcO157 and E. coli to lettuce fields, (3) identify the in-field mechanism(s) of contamination of lettuce, and to (4) develop and disseminate educational materials for growers of fresh produce and the livestock community about microbial water quality, potential impacts on down-stream stakeholders, and effective livestock production practices for improving water quality. These objectives will be completed in coordination and collaboration with the USDA, Agricultural Research Service (ARS).