By: Alice Vo Edwards
The recent E. coli outbreak linked with romaine lettuce has many people wondering: how does E. coli get into produce? E. coli is a bacteria that people and animals carry and excrete in their feces. Restaurant-related outbreaks of E. coli are often linked, for example, to poor handwashing practices. In the case of E. coli and produce, the progression of the E. coli can be a bit more confusing to follow.
Craig Hedberg, the Director of the Minnesota Integrated Food Safety Center of Excellence and an experienced environmental health epidemiologist studying foodborne illnesses discusses how E. coli can be carried from livestock to table.
- E. coli lives within the digestive tracts of livestock such as cows and sheep, as well as people.
- Livestock manure or human fecal matter can contain E. coli and can carry it across distances on wet or dry fecal matter.
- In communities where animal farms are situated nearby produce farms, it is possible for E. coli to travel from cattle farms into the water supply that is used to irrigate produce. For example, water drained from a farm into a local stream or water canal can contain particles of manure.
- If produce farms are situated near housing developments and share water supplies, it is also possible for E. coli to be transferred from people, through shared water resources, to the produce farm and to the produce.
- Workers involved in growing produce, packing produce, or preparing produce also can spread E. coli if they do not practice good hygiene.
This is not the first time produce has been the cause of an E. coli outbreak
In the spring of 2010, there was multistate lettuce-based E. coli outbreak. Crawford, Baloch, and Gerrity provided a report to the Food and Drug Administration on the investigation into the causes of that produce-based E. coli outbreak. While they identified six local potential sources nearby and could not conclusively determine which was the specific cause of the outbreak, the researchers concluded that a local R.V. park nearby was the likely culprit of the E. coli outbreak. In this instance, it was suspected that the R.V. park’s septic system and local soil become contaminated with E. coli. This was confirmed with Shiga Toxin-Producing E. coli (STEC) in soil samples taken from the R.V. Park. Additionally, there was a nearby pump and hose open to vehicles to dump and rinse out their R.V. septic system into the canal. Regardless of whether it was the R.V. park itself or an individual R.V. cleaning its septic tank with canal water, the source of the 2010 outbreak was most likely human-based.
What is the cause of the current E. coli romaine lettuce outbreak?
At this point in time, while Canadian officials have suggested that citizens not eat romaine lettuce, no particular farm or other source of contamination of the lettuce has been identified. The outbreak, so far, has affected people in 13 states and 5 eastern Canadian provinces as well. The CDC issued a statement on December 28, 2017 that the DNA of the bacteria is similar enough between what is affecting the Americans and Canadians that the outbreak is likely from the same source. It is likely the source is a large romaine lettuce producer that services these regions, but at this point in time, neither country has identified a culprit, nor the CDC has not ruled out that the United States infection may be from a secondary infection source.
Can you wash produce to remove the E. coli?
Hedberg has studied the E. coli bacteria extensively and says that he and other researchers have found that bacteria like E. coli are able to stick to produce like lettuce and can sometimes even get inside the fibers of produce so that they cannot be washed off. The experts still strongly suggest that washing produce is still a good idea, as it can definitely reduce the amount of bacteria that you are exposed to.
What can I do to protect my family from this E. coli outbreak?
While the CDC says they are “unable to recommend whether U.S. residents should avoid a particular food,” this outbreak is deadly. The Toronto Star reported on January 2nd that one person has died in Canada as well as one person in the United States. If you are concerned about whether your family members would be vulnerable to E. coli, it is advised that you consider some of the following actions.
- Wash hands! And often.
- Wash all produce. Better yet, cook it, too.
- If produce has been in your kitchen that may have been contaminated, thoroughly wash and disinfect any surface it may have touched, then wash your hands, again, with something that contains bleach or other substances that have been tested for their ability to kill coli. Studies have shown that anti-bacterial hand soap has little disinfectant ability against E. coli, so do not solely rely on handwashing with anti-bacterial hand soap.
- Where possible cook produce before eating it.
- Avoid romaine lettuce or any blend containing romaine lettuce
- When buying produce, by uncut produce. Cutting the produce gives coli an easy in to the interior of the vegetable, making it impossible to wash off.
- Do not rely on your dishwasher to sanitize your utensils for you, unless you know for certain that your dishwasher has a heating element that raises the water temperature above 160°F degrees – most do not. GE specifically says that they try recommend that the home water temperature that feeds the dishwasher be between 120°F and 150°F to keep from harming plastic items or heat-sensitive items placed in the dishwasher. If your home is at the lower end of this spectrum, and/or your dishwasher does not include an additional heating element to get the dishes over the 160°F threshold, your dishwasher will not sanitize well enough to completely remove the risk of coli surviving.