252663 Lessons learned about study design, sampling and testing techniques to describe fecal contamination routes on produce at the farm level

Monday, October 31, 2011: 4:30 PM

Elizabeth Adam, BS , Hubert Department of Global Health, Emory University, Atlanta, GA
Anna Fabiszewski, MPH , Hubert Department of Global Health, Emory University, Atlanta, GA
Faith Bartz, PhD , Hubert Department of Global Health, Emory University, Atlanta, GA
Elizabeth Bitler, BA , Hubert Department of Global Health, Emory University, Atlanta, GA
Gaelle Gourmelon, BS , Hubert Department of Global Health, Emory University, Atlanta, GA
Norma Heredia, PhD , Departamento de Microbiología, Universidad Autónoma de Nuevo León, Monterrey, Mexico
Santos Garcia, PhD , Departamento de Microbiología, Universidad Autónoma de Nuevo León, Monterrey, Mexico
Kruti Ravaliya, BS , Department of Food Science, North Carolina State University, Raleigh, NC
Lee-Ann Jaykus, PhD , Department of Food Science, North Carolina State University, Raleigh, NC
Elizabeth Ailes, MS , Department of Epidemiology, Emory University, Atlanta, GA
Juan Leon, PhD, MPH , Hubert Department of Global Health, Emory University, Atlanta, GA
Although farms and packing sheds have been implicated in several outbreaks caused by contaminated produce, contamination routes are not well understood. To address this, we completed two epidemiological field studies in farms and packing sheds on the US-Mexico border. In May, we pilot tested a novel study design in Mexico, to build on our past work. In our past studies, we collected 923 samples of produce and enumerated fecal indicators, including Escherichia coli (E. coli), by culture based methods, with limits of detection of 10 CFU/g. E. coli were found in 6 of 14 produce types, including cantaloupe. Produce type, packing step, country of origin, and season were significantly associated with E. coli contamination. Samples from the harvesting bin were nearly seven times more likely to be contaminated than those sampled directly from the field (OR = 6.77, 95% CI: 2.87 – 15.96), suggesting contamination occurred during harvest. Compared to the bin, wash-tank samples were a third as likely to be contaminated (OR = 0.32, 95% CI: 0.12 – 0.81), suggesting that produce washing decreased fecal contamination. A key limitation of our past work is that fecal contamination is often too low or focal to be observed at the production level. We will describe how we addressed these challenges in our current study by focusing on high-risk crops (jalapeño peppers, cantaloupes, tomatoes), designing novel field sampling methods, and by using molecular epidemiology techniques like Bacteriodales 16S rDNA microbial source tracking and E. coli strain-typing to identify the source of contamination.

Learning Areas:
Diversity and culture
Epidemiology
Planning of health education strategies, interventions, and programs
Protection of the public in relation to communicable diseases including prevention or control
Public health biology

Learning Objectives:
1. Discuss the implications of poor food safety from economic and community health perspectives 2. Define three challenges involved in identifying contamination routes at the farm level 3. Design a farm-level intervention to prevent fecal contamination of fruits and vegetables.

Keywords: Food Safety, Diarrhea

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am qualified because I was responsible for planning and conducting the presented research as a Master of Public Health student at Emory University.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.

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