A five-year study led by the U.S. Food and Drug Administration and the Western Center for Food Safety at the University of California, Davis, is providing new insights into how harmful bacteria move through the environment on California’s Central Coast, according to a March 12 announcement.
The Central Coast region, known as the nation’s “salad bowl,” produces more than 400 crops and has been linked to several foodborne illness outbreaks. The study aims to help scientists understand where disease-causing bacteria originate and how they spread, which is important for improving food safety practices in an area that supplies much of the country’s leafy greens.
Researchers collaborated with the FDA, the California Department of Food and Agriculture, ranchers, landowners, and growers. Rob Atwill, principal investigator for the Western Center for Food Safety and epidemiologist with UC Davis Weill School of Veterinary Medicine, said: “This was a five-year collaborative effort to test the environment within and surrounding produce fields, such as soil, surface water, sediment and air.”
The team collected feces from livestock and wildlife at various ranches and vineyards to better understand bacterial occurrence. Atwill said: “We could not have done this without our partnership with the California livestock and produce industries.” Initial findings showed detection of harmful strains of E. coli in animal feces from cattle, feral pigs, bobcats, deer, birds, coyotes and flies. The bacteria were found less often in farm soil overall but appeared more frequently near rivers or streams close to cattle ranches. Researchers also detected these organisms in rivers, creeks and sediment.
Multiple strains of E. coli O157:H7 were identified in environmental samples; however, researchers did not detect any strain linked to outbreaks between 2016 and 2020. Some strains found in wildlife closely matched those found in cattle or water sources. At one ranch different E. coli O157:H7 strains were detected each year among both cattle and wildlife.
Linda J. Harris, co-principal investigator with the Western Center for Food Safety and professor emerita at UC Davis Food Science and Technology department said: “The agricultural industry has made a lot of changes in the last decade to address food safety issues and our data support that they are focused on the right things.” She added: “These data will be used by the industry to inform future targeted research and refinements if needed to existing guidance on best practices for growers to reduce food safety risks.”
Analysis of hundreds of thousands of data points collected during this study is ongoing with further updates expected later this year.
