Online Program

Assessing microbial contamination on produce and farm worker hands throughout the production process on farms and packing sheds in northern Mexico

Tuesday, November 5, 2013 : 8:30 a.m. - 8:50 a.m.

Juan Leon, PhD, MPH, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA
Jacquelyn Lickness, BA, MPH candidate, Department of Global Health, Emory University, Atlanta, GA
Faith Bartz, PhD, Hubert Department of Global Health, Emory University, Atlanta, GA
Anna Fabiszewski de Aceituno, MPH, Hubert Department of Global Health, Emory University, Atlanta, GA
Lee-Ann Jaykus, PhD, Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC
Alice Parish, BS, BA, MPH Candidate, Department of Biostatistics, Emory University, Atlanta, GA
Santos Garcia, PhD, Ciencias Biologicas, UANL (Mexico), San Nicolas, Mexico
Introduction: Although produce associated outbreaks are a serious public health burden, few studies have characterized contamination routes or points in the production process where contamination has occurred. Thus, we aim to: 1) quantify contamination by fecal indicators on produce and farm workers' hands at different points in the chain of events surrounding the production and post-harvest handling process, and 2) assess the association of microbial levels between matched produce and hand rinse samples. Methods: Produce rinses (160 cantaloupe, jalapeño, and tomato samples) and matched farm worker hand rinses (107) were collected from 9 farms in northern Mexico at four points: before and after harvest, at the point of distribution from the field, and at the packing shed. Generic E. coli, Enterococci, fecal coliforms, and coliphage were enumerated. Results: Logistic regression found that the risk of E.coli presence on produce was 7 times greater when the matched handrinse had E.coli, (OR=7.1, 95% CI=2.3-21.6), and a significant increased risk was also seen with coliphage (OR=95.6, 95% CI=8.5-1076.4). Spearman's correlations indicated that the concentrations of E. coli (rho=0.9), Enterococci (rho=0.5), and coliphage (rho=0.7) were significantly correlated between hands and produce. Chi-square tests revealed that the prevalence of contamination on produce varied significantly across points in the chain for E. coli (χ2=21.9, p<0.001), Enterococci (χ2=23.5, p<0.001), and coliphage (χ2 =14.5, p=0.002). The prevalence of E. coli on produce increased from 28% before harvest to 67% at the packing shed, Enterococci increased from 69% to 90%, and coliphage from 38% to 61%. Discussion: Hand hygiene and the packing shed environment should be targeted for effective interventions to mitigate the risk of microbial hazards on produce.

Learning Areas:

Environmental health sciences
Planning of health education strategies, interventions, and programs
Public health biology
Public health or related research

Learning Objectives:
Identify points in the chain of events during the agricultural production process where the prevalence of microbial contamination on produce increases. Identify potential sources or vehicles of transfer of microbial contamination in the agricultural production environment. Describe appropriate interventions to reduce the risk of produce contamination in the agricultural production process.

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am a graduate research assistant with the Leon Research Group whose aim is to identify the routes of microbial contamination on produce in farms and packing sheds in the US-Mexico border. My role in this 4-year USDA-funded study is to manage a large data set of over 800 collected samples with over 60 measurements on each sample. I compared and reconciled all the discrepancies in the data entered by two separate study sites.
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.