Bacteria, specifically E. coli O157:H7 outbreaks and illnesses, linked to leafy greens have sickened hundreds in dozens of outbreaks in the last several years.  The "salad bowl" of the nation has been hit with recall upon recall.  No one, regulator, farmer, consumer or environmentalist knows quite what to do to protect consumers, business and the environment.  Perhaps, some "facts" would help?

The California Department of Fish and Game yesterday released a "[p]reliminary results from a joint E. coli environmental study found less than one half of one percent of 866 wild animals tested positive for Escherichia coli O157:H7 in Central California."  The press release further stated:

The study of water, soil, livestock and wildlife is being conducted by the University of California, Davis, the California Department of Fish and Game (DFG) and U.S. Department of Agriculture (USDA). It investigates the occurrence of the strain of E. coli that caused the disease outbreak in California agricultural fields in 2006.

Preliminary results from the wildlife portion of the study suggest less than one half of one percent of the wildlife tested positive for E. coli O157:H7. The finding is based on environmental sampling done over a two year period by government and university scientists from wild animals in the central coast region of California. Preliminary results from water, soil and livestock samples are not yet completed and may be reported separately.

The multi-agency study was prompted after state and federal investigators reported E. coli O157:H7 in 13 wild pig fecal samples tested during the 2006 spinach outbreak investigation in California. These findings led to concerns that wild animal feces may be one of several ways that produce fields or water sources are contaminated with E. coli O157:H7 or other harmful bacteria.

From 2007 through 2008, the research team collected 866 wildlife samples, including 311 black-tailed deer, 184 wild pig, 73 birds, 61 rabbits, 58 tule elk, 52 ground squirrels, 51 coyotes, 24 mice, 19 raccoons, 17 opossums and 16 striped skunks. Of the 866 animals sampled, 862 tested negative. The four positive samples included: one wild pig, one coyote and two tule elk. These findings are preliminary and the research team will continue to collect and test a total of 2,400 wildlife samples from this region.

Scientists are seeking to understand if certain species of wildlife are sources of E. coli O157:H7. These preliminary results indicate wildlife is not a primary source of E. coli O157:H7. The study findings will assist resource agencies and growers in developing strategies, and management plans and policies for preventing crop contamination in the fields to protect the public health and to protect wildlife and their habitats.

A previous study on free-ranging deer reported in the Journal of the American Veterinary Medicine Association estimated the fecal prevalence of E. coli O157:H7 to be similar to the prevalence in water and cattle fecal samples from the same region (Sargeant et al., 1999). All three of these sources are being investigated separately in this study.

Other studies have found similar or greater numbers in animals infected with E. coli O157:H7 and other bacteria:

Human Illness Caused by E. coli O157:H7 from Food and Non-food Sources

Food Safety Risks and Mitigation Strategies for Feral Swine (Sus scrofa) near Agriculture Fields

Implications of Wildlife in E. coli Outbreaks Associated with Leafy Green Produce

These preliminary findings might suggest that wild animals perhaps pose less of a risk to leafy green growing operations that originally thought.  In an article following the 2006 E. coli spinach outbreak that sickened 205, killing four, “Distributors Aim to Alter Farm Practices,” it was suggested that “some produce distributors are pressuring farmers to abandon practices that have long been considered environmentally friendly.” For example:

– Fresh Express, the nation’s No. 1 maker of packaged salads, is refusing to buy lettuce and spinach from farmers who don’t stop using compost and recycled water.

– Other shippers and handlers want farmers to stop planting native grasses that limit erosion but can attract animals and trap disease-causing bacteria.

The real issue is does this new preliminary study suggest that more research is needed to help determine the balance that needs to exist between environmental concerns and food safety concerns?  I think it does.