What Has the Ag Industry Learned from Foodborne Illness Outbreaks?
February 22, 2019 The outbreak of E. coli 0157:H7, linked to romaine lettuce from six California counties last fall, was declared over in January by the FDA and the CDC. Sixty-two people in 16 states became ill and 25 were hospitalized. At this writing, the investigation into how and where the contamination occurred continues.
This was the second outbreak last year tied to romaine lettuce from the western U.S. From March to June, 210 people in 36 states became sick. Tragically, five people died. The FDA traced that outbreak to Yuma, AZ, where large cattle-feeding operations are adjacent to fields of leafy greens.
Outbreaks like these affect an entire industry sector — no matter the location. In the most recent outbreak, the FDA issued a consumer advisory warning to not eat any kind of romaine lettuce. They eventually narrowed that broad statement, but not before other lettuce-growing regions, including Florida, were caught in the crosshairs. Florida romaine growers had not started harvesting their crops when the illnesses were reported, so Florida product could not have been to blame. Yet, at the start of the Florida season, the market for romaine shut down. Fortunately, after growers agreed to label their products with harvest location and dates, the FDA permitted producers outside the six California counties to sell their product.
Lessons Learned
Dr. Trevor Suslow, former Director of the University of California-Davis Postharvest Technology Center, and now Vice President of Food Safety for the Produce Marketing Association, presented on the topic at FFVA’s annual convention last fall.
It takes planning, coordination, and communication to protect consumers and the agriculture industry from disease outbreaks, he said.
“Any time an outbreak involving fresh produce is in the news, a geographic region or a whole product commodity can be affected,” Suslow said.
Suslow focused on multistate disease outbreaks, which constitute only 3% of outbreaks but result in 11% of sicknesses, 34% of hospitalizations, and 56% of deaths, according to the CDC. Salmonella, E. coli and Listeria, which have highly virulent subtypes, cause 91% of the most serious outbreaks.
It’s not easy for epidemiologists to trace the origins of a foodborne outbreak, since it typically takes weeks or months for consumers to become ill, for doctors to report patient illnesses, and for investigators to identify a disease pattern, Suslow said. Then come the more difficult questions of trying to determine if the outbreak originated from a grower, processor, or distributor, finding the root cause of the problem, and communicating the lessons to the industry.
Tracing the Source
The ag industry has adopted measures to improve tracing and isolating the source, thus limiting the economic damage to other producers. In addition, medical researchers now are able to identify the specific genetic aspects of bacterial and viral diseases and find links between seemingly isolated cases, Suslow added.
“An outbreak can often be traced back to a common convergence point,” Suslow said. For example, researchers investigating a papaya-related salmonella outbreak found that small herds of cattle, a common source of the bacteria, had been grazing in groves of papaya trees. In other cases, the disease source might be a continuing problem, such as a pathogen spread by birds, he added.
“Water runoff, dust, animals, agricultural traffic, and other risk factors must also be addressed,” Suslow said. In the Arizona romaine lettuce outbreak, for instance, contaminated sediment samples were found in a canal used for water supply.
Noting the importance of scientific investigation into the root causes of outbreaks, Suslow said, “We need to be sure the new generation of workers understands what happened in the past, so we don’t continue to make the same mistakes.”
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