Comanaging fresh produce for nature conservation and food safety.
In 2006, a deadly Escherichia coli O157:H7 outbreak in bagged spinach was traced to California's Central Coast region, where >70% of the salad vegetables sold in the United States are produced. Although no definitive cause for the outbreak could be determined, wildlife was implicated as a disease vector. Growers were subsequently pressured to minimize the intrusion of wildlife onto their farm fields by removing surrounding noncrop vegetation. How vegetation removal actually affects foodborne pathogens remains unknown, however. We combined a fine-scale land use map with three datasets comprising ∼250,000 enterohemorrhagic E. coli (EHEC), generic E. coli, and Salmonella tests in produce, irrigation water, and rodents to quantify whether seminatural vegetation surrounding farmland is associated with foodborne pathogen prevalence in California's Central Coast region. We found that EHEC in fresh produce increased by more than an order of magnitude from 2007 to 2013, despite extensive vegetation clearing at farm field margins. Furthermore, although EHEC prevalence in produce was highest on farms near areas suitable for livestock grazing, we found no evidence of increased EHEC, generic E. coli, or Salmonella near nongrazed, seminatural areas. Rather, pathogen prevalence increased the most on farms where noncrop vegetation was removed, calling into question reforms that promote vegetation removal to improve food safety. These results suggest a path forward for comanaging fresh produce farms for food safety and environmental quality, as federal food safety reforms spread across ∼4.5 M acres of US farmland.
Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720; The Nature Conservancy, San Francisco, CA 94105; danielsolkarp@gmail.com.
Daniel S
DS
Karp
The Nature Conservancy, San Francisco, CA 94105;
Sasha
S
Gennet
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616;
Christopher
C
Kilonzo
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616;
Melissa
M
Partyka
The Natural Capital Project, Stanford, CA 94305.
Nicolas
N
Chaumont
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616;
Edward R
ER
Atwill
Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720;
Claire
C
Kremen
D003247:Conservation of Natural Resources; D004926:Escherichia coli / Q000302:isolation & purification; D005516:Food Microbiology; D012475:Salmonella / Q000302:isolation & purification; D014675:Vegetables / Q000382:microbiology*
E. coli; agriculture; biodiversity; disease ecology; foodborne pathogens