The salad is usually synonymous with healthy eating. Except now, as the United States grapples with expansion cyclosporosis epidemic It sickened more than 7,100 people in Michigan alone, likely from iceberg lettuce provided by Taylor Farms.
In fact, leafy greens are frequently implicated in cases of foodborne illness. There was a multi-state in 2022 E.coli outbreak linked to romaine served on Wendy’s sandwiches and 173 cases of norovirus linked to DC Cobb’s restaurant in Illinois. In 2021, BrightFarms recalled packaged salad greens sold in several states after 31 people contracted salmonella. And in 2019, a total of 167 people were infected. E.coli after eating romaine harvested from the Salinas Valley region of California. This isn’t even the first cyclospora outbreak linked to lettuce: in 2020, Fresh Express salad kits were linked to more than 700 cases of people suffering from the parasite.
Centers for Disease Control and Prevention estimates These produce are responsible for nearly half of reported cases of foodborne illness, with leafy greens topping the list. So what makes lettuce a major source of food-related stomach problems in America?
One of the main reasons is simply that a lot of people eat them. Lettuce is the second most consumed vegetable in the United States behind potatoes. (The latest outbreak ensures that potatoes will remain the king of vegetables in the United States. Not counting fries.) Wraps, subs, tacos, you name a fast food sandwich and it almost certainly contains lettuce. Salad Chains are venues across the United States. Grocery store coolers are stocked with salad kits, in addition to no-frills heads of iceberg lettuce and containers of spinach.
These ready-to-eat salads and spring mix mixes pose a particularly acute risk because they contain multiple types of leafy greens, which may come from different farms and locations. If one type of lettuce in the mix is contaminated, it can contaminate the entire bag. And because this contaminated lettuce is packaged in so many bagged salads, it has the potential to spread germs everywhere.
The way lettuce is grown can also expose it to a wide range of pathogens. A Study 2025 by researchers at Cornell University who studied E.coli Outbreaks of romaine lettuce revealed that much of the contamination came from irrigation with untreated surface water applied through overhead spray irrigation systems. There are ways to reduce this risk, including switching to irrigation systems that don’t directly touch the leaves, but this would require upgrades and downtime.
Lettuce’s satisfying crunch is also what makes it vulnerable to pesky pathogens. Since it is eaten raw (really, who wants wilted lettuce?), there is no opportunity to remove any lingering contaminants. Like other raw fruits and produce, leafy greens do not go through what is called a “kill stage”: heating, pasteurization or freezing, designed to eliminate pathogens during the food manufacturing process.
The texture of lettuce is an additional factor in its ability to spread disease. “Many types of lettuce have many cracks and wrinkles,” says Jeanne Marrazzo, CEO of the Infectious Diseases Society of America. “It’s very easy for these tiny pathogens to get in.”
Even pre-washing procedures in manufacturing plants don’t always eliminate microbes, which can cling tightly to leaves. In the case of Cyclospora, the parasite has thick outer walls, making it very resistant to most food disinfectants. Experts say that vigorous washing involving scrubbing is the best way to get rid of cyclospora.
“If you don’t wash these products well, you’ll end up ingesting everything that’s on the lettuce,” says Amira Roess, an epidemiologist at George Mason University.
