eNewsletter, August 2017
May 2017 | WCFS & WIFSS Newsletter
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We've been hard at work this month making food safer and more secure. Please have a look at where we've been. We hope you find it informative. Stop by our websites at either or Thank you for your continued support!

University of California, Davis

Go to:   Meetings   |  Outreach   |   Training


From left, Greg Goblick, Yaping Ao, Melissa Partyka, and Ronald Bond after finishing up a dye-tracer demonstration study in the California Delta.
FDA CFSAN Water Team Site Visit to WCFS | August 1-4, 2017, Davis, CA

Kruti Ravaliya, Chelsea Davidson, Gregory Goblick, and Yaping Ao from CFSAN met with Rob Atwill, Melissa Partyka, and Ronald Bond to discuss current research being conducted by the Atwill Lab as it relates to current regulatory policy for the testing of agricultural water supplies.  The group spent Tuesday touring agricultural areas and water purveyance systems in Yolo-Solano counties followed by discussion of the challenges in studying agricultural water quality.  Mr. Goblick and Ms. Ao, both engineers affiliated with the Shellfish and Aquaculture Policy Branch within the Office of Food Safety, are experienced in modeling the impact of contamination in coastal water supplies and have interest in collaborating with the Atwill lab in studying irrigation water supplies. The visit culminated in a demonstration of capabilities by the Atwill lab and the FDA through a brief dye-tracer experiment in the Sacramento-San Joaquin Delta with great success. The group is now moving forward with plans for an in-Depth collaboration during next year’s irrigation season.


Linda Harris, Postdoctoral Fellow Setareh Shiroodi and Adrian Sbodio from Trevor Suslow’s laboratory met with about 30 members of the California citrus packinghouse industry to discuss their research on preventing cross contamination in a citrus packinghouse. The meeting was organized by the California Citrus Quality Council and was held at the University of California ANR Lindcove Research and Extension Center near Exeter, CA.  The meeting included a discussion of research results, challenges faced by the packinghouse industry, and potential collaborative research projects.

Lambertini, E., J. Barouei, D. W. Schaffner, M. D. Danyluk, and L. J. Harris.  2017. Modeling the risk of salmonellosis from consumption of pistachios produced and consumed in the United States.  Food Microbiol. 67:85-96.

•4 ± 0 log treatments reduced risk of salmonellosis from pistachios to <1 case/year.
•Risk of salmonellosis is greater for product derived from floaters than from sinkers.
•≥0.05% of untreated product volume yielded >1 case/year of salmonellosis.
•Salmonellosis risk decreased 10-fold when Salmonella storage decline was considered.

Abstract available here.
Updates to the water calculator tool to correct an odd calculation error
Mashiana, R. and L. J. Harris. August 28, 2017. Determining your microbiological water quality profile (MWQP) for untreated ground water used in the production of fresh produce, Version 4.0. (Excel spreadsheet–based tool.) Available at:
Mashiana, R. and L. J. Harris. August 28, 2017. Determining your microbiological water quality profile (MWQP) for untreated surface water used in the production of fresh produce, Version 5.0. (Excel spreadsheet–based tool.) Available at: 
Four chapters in the same book just came out in with WCFS authors 

Control of Salmonella and Other Bacterial Pathogens in Low Moisture Foods

Anderson, D., N. Anderson, L. J. Harris, and W. Ocasio. 2017. Validation requirements in heat-processed low-moisture foods, p. 149-173. In R. Podolak, and D. G. Black (eds.), Control of Salmonella and other bacterial pathogens in low moisture foods. John Wiley & Sons, Ltd, Chichester, DOI: 10.1002/9781119071051.ch7

Enache, E., R. Podolak, A. Kataoka, and L. J. Harris. 2017. Persistence of Salmonella and other bacterial pathogens in low-moisture foods, p. 67-86. In R. Podolak, and D. G. Black (eds.), Control of Salmonella and other bacterial pathogens in low moisture foods. John Wiley & Sons, Ltd, Chichester, UK. DOI: 10.1002/9781119071051.ch4

Podolak, R., L. Lucore, and L. J. Harris. 2017. Heat resistance of Salmonella and other bacterial pathogens in low-moisture foods, p. 121-148. In R. Podolak, and D. G. Black (eds.), Control of Salmonella and other bacterial pathogens in low moisture foods. John Wiley & Sons, Ltd, Chichester, DOI: 10.1002/9781119071051.ch6

Santillana Farakos, S. M., M. Danyluk, D. Schaffner, R. Pouillot, L. J. Harris, B. P. Marks. 2017. Modeling and statistical issues related to Salmonella in low water activity foods, p. 219-239. In R. Podolak, and D. G. Black (eds.), Control of Salmonella and other bacterial pathogens in low moisture foods. John Wiley & Sons, Ltd, Chichester, DOI: 10.1002/9781119071051.ch10
Proceedings of the 27th Vertebrate Pest Conference are now available

Contact the authors for a copy of the reprint

Navarro-Gonzalez, N., M. T. Jay-Russell. 2017. Use of falconry to deter nuisance birds in leafy greens fields in Northern California. Proceedings of the 27th Vertebrate Pest Conference pp. 209-216.
Abstract: Some species of birds form large flocks that forage on agricultural fields and frequently damage the crop, resulting in significant economic losses. Additionally, by defecating they potentially contaminate the crop and farm equipment with pathogens, which is of special concern for leafy greens that are consumed uncooked. There is a need to find an effective deterrent that is also environmentally friendly, and falconry is an ideal candidate for this purpose. To evaluate falconry as deterrent of nuisance birds in leafy greens field in northern California, we performed a set of trials on a control ranch and a treatment ranch of similar production and landscape characteristics. We identified avian species, counted individuals, and recorded flock size in daily surveys pre- treatment, during treatment (falconry), and post-treatment. Bird abundance was lower in spring than in fall, probably because many fields were fallow in spring. In both seasons, we observed a large daily variation in the bird abundance and their use of the fields in the surveys pre-treatment. In fall, the first trial was interfered by the activity of a falconer in an adjacent vineyard and the harvest of the grapes. Importantly, in the second trial, use of the field (e.g., foraging, etc.) decreased during five days of treatment and continued to be low for three days post-treatment, suggesting a “memory effect” after hazing by falconry. Interestingly, the third fall trial coincided with the end of the leafy greens growing season and showed that falconry successfully minimized use of the field by nuisance birds during peak activity. These results indicate that falconry is an effective measure to protect leafy green crops from fecal contamination and damage, but further research is needed at more farms in different regions, and the effect of using falconry in
combination with other non-lethal bird abatement approaches (e.g., audio-visual deterrents) should also be evaluated.

Rivadeneira, P., C. Hilson, A. Justice-Allen, M. Jay-Russell. 2017. Pathogen risks related to the movement of birds frequenting livestock and fresh produce growing areas in the Southwestern U.S. Proceedings of the 27th Vertebrate Pest Conference pp. 258-263.
Abstract: Concentrated animal feeding operations (CAFOs) are sometimes located in close proximity to fresh produce fields, both of which serve as easily accessible food and water sources for wild birds. When birds travel between these two areas, they have the potential to transfer pathogens from cattle, a documented source of enteric zoonotic foodborne pathogens, to fresh produce crops through fecal deposition. However, the presence of pathogens in wild birds is not a risk unless the birds or their fecal material come into contact with fresh produce crops. Therefore, the objective of this study was to determine if birds visiting CAFOs use flyways that cross fresh produce fields, thereby increasing the risk for contaminating fresh produce intended for human consumption. During 2014, birds trapped at a CAFO in southern Arizona were fitted with Lotek nano-coded radiotransmitters. Two receivers were placed at the CAFO and two receivers were placed in nearby fresh produce fields. A total of 103 birds were fitted with radiotransmitters, including 66 red-winged blackbirds, 21 Eurasian collared doves, 11 brown-headed cowbirds, four common ravens, and one European starling. Over four million data points were collected indicating the date, time, and bird ID number for each time a bird was recorded within 1 km of a receiver. Radiotelemetry results showed that birds travel regularly between the CAFO and fresh produce fields. Using PCR and culture techniques, 2 (1.9%) birds tested positive for Salmonella, and 5 (4.9%) tested positive for non-O157 Shiga toxin-producing Escherichia coli (STEC). During the same time period, Salmonella (4%), STEC O157 (16%), and non-O157 STEC (44.5%) were detected in 400 cattle fecal samples from the CAFO. Our results will aid in determining the pathogen risks that birds pose to fresh produce when they are frequent visitors to a CAFO and fresh produce fields.

Sellers,L., R. Long, R. A. Baldwin, M. Jay-Russell, X. Li, E. R. Atwill, R. M. Engeman. 2017. Impact of field border plantings on rodents and food safety concerns. Proceedings of the 27th Vertebrate Pest Conference pp. 264-267.
Abstract: This one-year study focused on the impact of hedgerows of native California plants on rodents and food safety in adjacent crops in the Sacramento Valley. Deer mice, house mice, California voles, and western harvest mice were live trapped in four different walnut orchards at zero, 10, 75, 175-m transects from hedgerows. The abundance and richness of rodents was compared to control sites with conventionally managed field edges that were mowed or sprayed for weed control. Unique rodent capture data showed two peaks in activity: 1) in the middle of the orchard regardless of field border type, and 2) in the hedgerow across all seasons with winter being the most active overall. Fewer captures were recorded in the conventional field border, likely because they lacked vegetative structure. Deer mice were the most prevalent species captured throughout the study (>96% of unique captures). House mice and California voles were almost always found in hedgerows and not in adjacent crops. Fecal samples from captured rodents showed a low prevalence of Escherichia coli (non-O157 STEC 1.4%, n = 438; O157 STEC 0%, n = 434) and Salmonella (0.92%, n = 434). Giardia (28.6%, n = 210) and Cryptosporidium (23.8%, n = 210) were more prevalent in captured rodents, but the distribution was not affected by field-edge habitat.

Order the full Proceedings book at:

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