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Davis, California

Monday, April 15, 2024

The state of E. coli outbreaks

Vomiting, abdominal pain and bloody diarrhea: the symptoms of an E. coli O157:H7 infection.

If consumed, these rod-shaped bacteria can lead to kidney failure and death. So how does this strain of E. coli find its way into our food and what consequences does it have for producers and consumers?

“It all starts with the cow; a little simplistic, but an easy concept,” said Trevor Suslow, plant pathologist for the UC Davis department of plant science.

He said E. coli contamination often starts with manure that is picked up by water runoff that finds its way into the water supply of crops.

“Along with doing what they can to keep the water from getting contaminated, the [produce] industry really focuses on identifying, marking and buffering areas of harvest affected by animal intrusion and flood waters,” Suslow said.

He said that cattle are not susceptible to E. coli O157:H7 as a result of not having the attachment sites on their cells for toxins that humans have. Suslow also said that E. coli have other traits that give them the ability to adapt to severe conditions, such as low pH levels and the ability to hang on food surfaces much longer than people originally thought.

“They pick up traits that allow them to do this,” Suslow said.

He said that the E. coli spinach outbreak in 2006 made the produce industry come together to have a more standardized way to help minimize the chances of E. coli outbreaks. Suslow referred to the California Leafy Greens Marketing Agreement (LGMA) as an example of this standardization. The LGMA utilizes mandatory government inspections and science-based food safety practices to make leafy green products safe for consumers.

Christine Bruhn, director of the UC Davis Center for Consumer Research, said that over the past five years, outbreaks associated with meat have decreased; meanwhile, produce outbreaks have increased.

“Outbreaks associated with meat have probably decreased because the meat industry has adopted several strategies to reduce the possibility of contamination,” Bruhn said.

She said that the increase in produce outbreaks could be due to increased consumption of fresh produce and eating produce raw, along with aggressive reporting by the media. Nonetheless, Bruhn said that response to outbreaks varies among consumers.

“If the outbreak is widely publicized, some people will stop eating the food for a short period of time, then when the outbreak is over, and the contaminated food is off the market, they will go back to buying it,” Bruhn said. “If a product is recalled frequently, some people will stop eating the food for a long time.”

She mentioned that she knows some people that no longer eat burgers made from beef, but instead replace it with turkey – a product that still presents the chance for salmonella if not cooked properly.

Bruhn said that the effect an outbreak has on sales depends on how much people like the product. She mentioned that during the 2008 tomato recall, many people continued eating tomatoes; meanwhile, after the 2006 spinach recall, sales took several months to recover.

When asked whether public reaction to these outbreaks has changed over the years, Bruhn mentioned that today’s standards are stricter and people are less tolerant, but that people were “shocked” in 1993 during the beef outbreak.

“It affected the food industry profoundly,” Bruhn said. “When E. coli is associated with a commodity, the industry focuses on what factors led to the contamination and how future outbreaks can be prevented.”

Karen Klonsky, an agriculture and resource economist with the UC Davis cooperative extension, said that producers are more affected in the short run than in the long run.

“In the short run, producers pulled more stuff [referring to spinach outbreak] than needed from the shelf because people didn’t want to buy,” she said.

Klonsky said that these producers lose crops in the short run, but that the demand usually comes back after a few months. She said that one of the greatest tools growers have now is diversification, in terms of both location and the crops they grow.

E. coli has not disappeared, as seen by the recent Lebanon Bologna and in-shell hazelnut outbreaks in the eastern U.S.; however, farmers and growers are uniting to do what they can to prevent more outbreaks from happening.

As Suslow said, “everybody does not need to be doing everything, but everybody should be doing something.”

For more information on safe handling of fruits and vegetables, go to ucanr.org/freepubs.

ERIC C. LIPSKY can be reached at science@theaggie.org.


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