Salad is normal same as healthy eating. But now, when the United States is struggling to expand outbreak of cyclosporiasis which sickens more than 7,100 people in Michigan alone, which may have been caused by iceberg lettuce provided by Taylor Farms.
In fact, leafy vegetables are often implicated in cases of foodborne illness. There were many 2022 governments E. coli an outbreak linked to romaine served on Wendy’s sandwiches and 173 cases of norovirus linked to Illinois eatery DC Cobb’s. 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 pomegranates harvested from the Salinas Valley area in California. This is not the first cyclospora outbreak linked to lettuce: In 2020, Fresh Express salad dressings were linked to more than 700 cases of people affected by the parasite.
Centers for Disease Control and Prevention estimates those crops are responsible for nearly half of all reported foodborne illness cases, with leafy vegetables topping the list. So what makes lettuce the leading cause of America’s stomach problems?
One big reason is because many people eat. Lettuce is the second most consumed vegetable in the United States behind potatoes. (The latest explosion ensures that the potato will remain the king of American vegetables. Plus, french fries.) Wraps, subs, tacos, you name a fast food sandwich and it’s almost got a lettuce salad. Salad-slinging chains is a fix across the US. Grocery stores are stocked with salad dressings, over unadorned heads of iceberg lettuce and containers of spinach.
Those ready-to-eat salads and spring mix mixes are particularly dangerous because they contain many types of leafy greens, which can come from different fields and regions. If one type of lettuce in the mix is contaminated, it can contaminate the entire bag. And because that contaminated lettuce is put into lots and lots of bagged salads, it has the potential to spread all kinds of germs.
The way lettuce is grown can also expose it to a wide range of pathogens. A 2025 study and researchers at Cornell University who studied E. coli outbreaks in romaine lettuce found that most contamination comes from irrigation water and untreated water applied through high-spray irrigation systems. There are ways to reduce that risk, including switching to irrigation systems that don’t touch the leaves directly, but that would require optimization and less time.
The satisfying combination of lettuce is also what makes it susceptible to dangerous pathogens. Since it’s not eaten fresh—really, who wants wilted lettuce—there’s no opportunity to remove any lingering dirt. Like fruits and other fresh produce, leafy greens do not go through a so-called “killing step” — heating, incubation, or freezing — that is designed to eliminate pathogens during the food manufacturing process.
The texture of lettuce is an additional factor in its ability to spread disease. “Most types of lettuce have a lot of cracks and folds,” says Jeanne Marrazzo, CEO of the Infectious Diseases Society of America. “It’s very easy for these little bugs to get in there.”
Even the pre-washing procedures in the production facilities do not always remove the germs, which can be strongly attached to the leaves. In the case of cyclospora, the bacterium has thick outer walls, making it resistant to many food detergents. Experts say vigorous washing that involves scrubbing is the best way to get rid of cyclospora.
“If you don’t wash these products properly, you end up ingesting whatever is in the lettuce,” says Amira Roess, an epidemiologist at George Mason University.
