Posts Tagged: Michele Jay-Russell
Low food-safety risk at Northern California farmers markets
A new study by UC Davis researchers finds a low risk of contamination of foodborne pathogens on produce and meat at Northern California certified farmers markets, but still finds cause for some concern.
The study, published in the Journal of Food Protection, examined the prevalence of Salmonella on meat and produce, as well as the prevalence of generic E. coli on produce. Samples were taken from 44 certified Northern California farmers markets, including in the Sacramento region and Bay Area. Less than 2% (1.8%) of animal products sampled, including beef, pork and poultry, tested positive for Salmonella, while all produce samples tested negative. Slightly more than 30 percent (31.3%) of produce tested positive for generic E. coli. Generic E. coli is an indication of fecal contamination, but not all E. coli is harmful. This study didn't test for pathogenic E. coli.
“Based on this data, I think it's safe to consume meat and produce from farmers markets,” said lead author Alda Pires, a UC Cooperative Extension specialist and research scientist in the UC Davis School of Veterinary Medicine. “That's a low risk of contamination of foodborne pathogens, especially Salmonella.”
While the prevalence of generic E. coli may seem relatively high, the concentrations were low. Pires said that's especially so compared to previous studies of contamination at farmers markets elsewhere in the United States. The prevalence of Salmonella in meat sampled from Northern California farmers markets is also much lower than what previous studies have found in grocery stores.
Among the produce sampled, leafy greens had the highest prevalence of E. coli, followed by root vegetables.
Consumers should still be cautious
Consumers and farmers should still be aware that produce and meat were not free from contamination. Consumers need to make sure the foods they prepare from farmers markets follow the good hygiene practices recommended by Centers for Disease Control and Prevention. Consumers should also keep produce separate from meat to avoid cross-contamination.
“The study raises awareness that it's not just very large farms that can have contamination,” said co-author Michele Jay-Russell, with the Western Center for Food Safety at UC Davis. “Farmers need to pay attention to everything they're doing, from planting to storage, to avoid contamination.”
While certified farmers markets are inspected for food hygiene, microbiological quality is not explored. Smaller farms, those making less than $25,000 a year, are also exempt from certain food-safety provisions of the U.S. Food and Drug Administration's Food Safety and Modernization Act. Foodborne illness costs the U.S. economy more than $15 billion annually.
Other co-authors include James Stover, Esther Kukielka, Viktoria Haghani, Peiman Aminabadi and Thais De Melo Ramos of UC Davis. Research support came from the U.S. Department of Agriculture.
Organic produce growers sought for research study
“The goal of our study is to provide organic farmers with science-based strategies that effectively limit food-safety risks when using raw manure-based soil amendments,” said Alda Pires, UC Cooperative Extension urban agriculture and food safety specialist in the School of Veterinary Medicine at UC Davis.
To study the survival of pathogens in soil and soil health, UC scientists are recruiting California growers who use raw or untreated manure in organically grown crop fields.
Pires is leading the project in California with Michele Jay-Russell, a veterinary research microbiologist and manager at the Western Center for Food Safety at UC Davis.
The researchers will visit participating farms eight times over the 2017-2018 growing season.
“We will collect produce, water, soil and manure samples,” said Jay-Russell. “All of the samples will be tested for bacterial indicators such as nonpathogenic E. coli and pathogens. We will ask the farmers to complete a short survey. The study is voluntary and all locations and names will be kept confidential.”
Eligible California farms must be certified as organic by the National Organic Program or California Certified Organic Farmers and fertilize with raw manure or untreated manure from dairy cattle, horses or poultry. The farms can grow any of the following produce: lettuce, spinach, carrots, radishes, tomatoes or cucumbers.
For more information or to enroll in the project, please contact Pires at (530) 754-9855 or firstname.lastname@example.org, or Jay-Russell at (530) 219-4628 or email@example.com.
This study is being conducted in other states by the University of Minnesota, University of Maine, USDA Agricultural Research Service's Beltsville Agricultural Center, USDA Economic Research Service's Resource and Rural Economics Division, Cornell University and The Organic Center. The project is funded by a U.S. Department of Agriculture Organic Research and Extension Initiative grant.
New study focuses on food safety practices on small and medium-size farms
A new UC study is looking at small to medium-size farms, both organic and conventional production, to identify on-farm food safety practices that are specific to farms that raise livestock and grow fresh produce. These are farms that sell their products directly to consumers at farm stands and farmers markets or through community supported agriculture (CSA).
“Much of the produce food-safety research in recent years has focused on large commercial farms,” said project co-leader Michele Jay-Russell, microbiologist and program manager at the Western Center for Food Safety at UC Davis. “In this study, we hope to identify best practices that may be unique for smaller operations and to share this information with the farmers.”
The 12-month study is being conducted on commercial farms in Northern California, from the Shasta Cascade region down to the Central Valley, including the coast. Fecal-borne pathogens can be spread to fresh fruits, nuts, and vegetables through animal intrusions, or indirectly through contaminated water or soil. The researchers are looking for the best practices that prevent pathogens from contaminating fresh market tomatoes and leafy greens such as lettuce and spinach.
“Raising livestock and growing fresh produce together for the local community presents certain opportunities and challenges from a food safety perspective,” said Alda Pires, UC ANR Cooperative Extension urban agriculture and food safety specialist in the School of Veterinary Medicine at UC Davis, who is leading the project with Jay-Russell, who is liaison to the Western Institute for Food Safety and Security.
“Our research aims to identify practical, scale-appropriate approaches that reduce risk from pathogens, while maintaining sustainable and economically viable family farms in Northern California,” said Jay-Russell, who has a small dairy goat herd in the Yuba Foothills.
Researchers will visit participating farms to collect samples of their produce, water, compost and livestock feces to test for bacteria. Farmers will be asked to complete a short survey about farm management practices. The testing is free and the farm identities are confidential.
“We anticipate publishing our results, without revealing farm names, next year and sharing the findings with the agricultural community through workshops and trainings,” said Pires, who grew up on a small family farm in Portugal.
A USDA National Institute for Food and Agriculture (NIFA) multi-state grant is funding this study and a similar study in the northeast – New Jersey, Maryland and Delaware – looking at microbial food safety issues potentially unique to small and medium-scale farms. The results of that study have been published in the International Journal of Food Microbiology and Applied Environmental Microbiology.
For more information about this food safety study, contact Alda Pires, UC ANR Cooperative Extension urban agriculture and food safety specialist, at (530) 754-9855 or firstname.lastname@example.org.
What's in your compost?
Michele Jay-Russell, a veterinarian and research microbiologist at the Western Institute for Food Safety and Security (WIFSS) and program manager of the Western Center for Food Safety (WCFS), recently co-authored a study that highlights the need to be aware of the hazards associated with using raw animal manure to fertilize home gardens. (Read full article here.)
The basis for the study began in July of 2010 when a shire mare from a rural Northern California farm was brought to the William R. Pritchard Veterinary Medical Teaching Hospital for treatment of colic. Following protocol, the veterinarians on call screened the horse for Salmonella to avoid infecting other horses during hospitalization. She tested positive and after successful treatment for colic, went home. Her owners then notified the veterinarians that some of their other draft horses were sick as well — all 8 were tested and 6 came back positive for the same Salmonella Oranienburg strain, including the mare that still had the infection.
Jay-Russell heard about the case from her colleague John Madigan, professor of medicine and epidemiology at the school. The farm’s owners invited Jay-Russell and Madigan to the farm to see if they could uncover the source of the Salmonella infection. They sampled water from horse troughs, manure storage piles, wild turkey feces and soil from the family’s edible home garden where raw horse manure had been used as fertilizer. Each of those locations had a percentage of positive samples over the sampling period from August 2010 to March 2011.
“We showed the owners how to continue collecting samples and provided them with a FedEx number to ship them to UC Davis,” Jay-Russell said. “During that whole time, the garden soil kept coming back positive, which showed that this strain of Salmonella could persist for months.”
While the researchers couldn’t be completely certain about the original source of Salmonella on the farm, they suspect that a recent surge in the wild turkey population on the property introduced the bacteria to the horses by pooping in the horse corrals and in the water troughs. They speculated that the wild turkeys brought the Salmonella onto the property, although they couldn’t rule out the possibility that the birds were exposed on the farm or to other potential sources of Salmonella.
“What is clearer is that the raw horse manure applied as fertilizer was the most likely source of garden soil contamination,” Jay-Russell explained. “We suspect that the damp climate in Mendocino County may have contributed to the longevity of this bacterium in the soil long after the owners stopped applying the horse manure to the garden. Fortunately, the owners didn’t get sick, but our investigation showed the potential for widespread dissemination of Salmonella in a farm environment following equine infection.”
To promote safe gardening practices, Jay-Russell has teamed with Trevor Suslow, a Cooperative Extension food safety specialist in the Department of Plant Sciences, to speak to groups of small farmers around the state about best practices. They also use a brochure in English and Spanish, “Food Safety Tips for Your Edible Home Garden,” that includes information about safe uses of animal manure and ways to minimize animal fecal contamination.
“It’s good to let people know about the risks and to correct misinformation about ways to treat the compost pile before using it in the garden,” Jay-Russell said. “The biggest take home message from this experience is to be very careful about using manure from sick horses — and to be cautious about offers of free manure — you don’t know what’s in there. Commercial compost should be bought from a reputable source.”
She urges gardeners to take a class and learn how to compost correctly and safely. Each county in California has UC Cooperative Extension advisors and many have Master Gardener programs offering information on food safety.