By: Kate Delany
It’s strange to think of salad as anything other than a healthy food choice, but at present, steering away from any meal that might contain romaine is in consumers’ best interests. The current E. coli outbreak caused by contaminated romaine lettuce now spans 25 states. The CDC is aware of 121 cases of infection in individuals ranging from 1-88 years of age. But more cases may be linked to the outbreak in coming weeks, especially as the most recent reported case is only April 21, 2018. According to New Scientist “kidney failure…has been reported in 14 of the 52 people who have been hospitalized during the outbreak.”
There has also been one confirmed death, in California. And the outbreak is expected to continue to grow in numbers, according to the CDC:
“The most recent illness started on April 21, 2018. Illnesses that occurred in the last two to three weeks might not yet be reported because of the time between when a person becomes ill with E. coli and when the illness is reported to CDC.”
Without a recall yet initiated, this continues to be concerning.
These are some pretty scary side effects from eating lettuce!
But why so serious?
Part of the reason why the outbreak is so severe is because of the particular strain of E. coli involved. Shiga toxin-producing Escherichia coliO157:H7, or STEC for short, causes more serious illnesses in infected individuals than other common E. coli strains. Those who are elderly, very young, and have weakened immune systems are especially at risk for complications and more severe illnesses. The Shiga toxin is particularly detrimental to kidney function and can lead to hemolytic uremic syndrome, or HUS. Typical HUS symptoms include: facial pallor, decreased urination and lethargy. While most people who contract HUS recover in a few weeks, it can be life threatening or lead to permanent kidney damage.
Because of the severity of the E. coli strain and the wide scope of the outbreak, the CDC is currently recommending that people avoid eating all romaine lettuce unless they can definitely confirm that it was not grown in the Yuma, Arizona region. While the lettuce is no longer being shipped from this growing region, there is still a chance that infected lettuce is in circulation due to the product’s permitted 21-day shelf life. Bagged salad mixes are also to be avoided. As the CDC notes: “If you do not know if the lettuce in a salad mix is romaine, do not eat it.”
A Little About E. coli
The bacterium known as E. coli can be found in the intestines of humans and animals, as well as in food and the environment. Most strains cause little harm beyond intestinal distress. This outbreak is unique in its severity. It is not unique, however, for the contaminated food to be a leafy green. The CDC data reported in 2013 revealed that nearly a quarter of all food poisoning cases involve leafy greens. This far outpaces incidence of food contamination in meat, dairy, poultry, or fish.
So, why is lettuce or leafy green contamination so common? Partly, it’s because leafy greens are eaten raw. Cooking at adequate temperatures can kill pathogens in other food items. Also, because it is grown so close to the ground, lettuce and greens are at additional contamination risk. Dirt, fecal matter, and bacteria are pulled onto the plant by rain and irrigation. Also, if the crops are in contact with animals and animal vectors, that can pose additional contamination concerns.
Improper handling can cause further difficulties. As Rachel Nobel, a biologist and professor in the Department of Environmental Sciences and Engineering at the University of North Carolina at Chapel Hill, notes, “Any commercially grown lettuce product will be put through some basic wash step before it’s sold…The series of baths and tumblers is not a thorough cleaning, however; it’s just enough that the end product is appealing to the customer.” While commercial growers do test for E. coli, not every single product of leafy greens is necessarily inspected thoroughly. Additionally, greens or any other products could potentially become contaminated by food handlers who have not observed adequate hygiene before coming in contact with the food. Even individuals throughout the distribution chain could potentially contaminate food.
In the Meantime…
While it’s not clear how long this current STEC lettuce outbreak will endure, the CDC does offer advice on how to maximize safety when consuming leafy greens. Most critical are proper handwashing and kitchen sanitation. Washing the product gently with water will remove most contaminates. Specialty, produce washes are of dubious extra value.
Bagged lettuce mixes, a popular convenience product, are always at greater risk for contamination than whole heads of lettuce. Because multiple greens are pre-chopped and mixed, it ups the likelihood of bacteria in one bag. It is also more difficult to determine which pieces of lettuce may be contaminated, as the greens may derive from different farms. Because the mixes are sealed in plastic bags then shipped and left on shelves, there is plenty of time for pathogen to incubate. Also, it is likely that the product label will specify a more vague origin than the whole lettuce product.
While the answer to this quandary isn’t to avoid lettuce altogether, it may be time for the public to rethink this convenience product, weighing the potential health risks. And for all lettuce and all food eaten raw, adequate washing and proper hygiene are pivotal for safe consumption. When washing, it is a good idea to remove the outermost leaves of the whole heads and dry everything with a clean paper towel.
It is also good to remember that product labels often do not identify the growing regions of a particular product. So, do not eat or buy romaine lettuce if you do not know where it was grown. The old adage “when in doubt, throw it out,” is a good mantra for now.