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Ongoing outbreaks of a diarrhea-causing illness possibly linked to fresh produce might have left you second-guessing which fruits and vegetables to add to your cart at the grocery store over the past few weeks.
At least 1,645 people in 34 U.S. states have been infected with cyclosporiasis, an illness caused by the parasite Cyclospora, since May, according to the Centers for Disease Control and Prevention (CDC). The CDC is also awaiting confirmation on more than 5,100 additional suspected cases (just 249 cases were reported nationally to the CDC during the same period last year)
“When cases explode like this, there is certainly a food related to the increase in cases,” says Camila Rodrigues, Ph.D., assistant professor and food safety extension specialist at Auburn University.
For weeks, public health officials have been trying to figure out which food is causing these infections, and now we finally have an answer: shredded iceberg lettuce supplied to Taco Bell from a single supplier.
The CDC found that 1,644 people sick with cyclosporiasis reported eating at Taco Bell in five states: Indiana, Kentucky, Michigan, Ohio, and West Virginia. It’s warning people to avoid shredded iceberg lettuce from Taco Bell locations in these states. Taco Bell is working to stop using this lettuce, and the Food and Drug Administration (FDA) is working with the supplier to determine whether contaminated lettuce went elsewhere, too.
The case isn’t exactly closed, however. The CDC is still investigating other outbreaks and illnesses of cyclosporiasis that are unrelated to this one. Past Cyclospora outbreaks have been linked to contaminated bagged salad mixes and kits, fresh cilantro and basil, raspberries, snow peas, and green onions.
Here’s how we got here—and how to stay safe.
What is cyclospora?
Cyclospora (Cyclospora cayetanensis) is a parasite spread by food or water contaminated with fecal matter. If you ingest contaminated food, Cyclospora can invade your intestines. The most common symptom is frequent, watery diarrhea that usually starts within two days to two weeks of exposure. Some people also experience a poor appetite, unintentional weight loss, cramping, bloating, gas, nausea, and fatigue. Symptoms can vary widely from person to person. Some people feel sick for only a few days, while others have symptoms that linger for months. Fortunately, this Cyclospora outbreak hasn’t caused any deaths, but 114 people have been hospitalized, according to CDC data.
When Brandon Brown, Ph.D., a public health epidemiologist and professor of medicine in the UC Riverside School of Medicine, contracted cyclosporiasis in 2018, he was visiting the bathroom about four times an hour. His symptoms waned for a while, then came roaring back.
“A month later, I’d lost 20 pounds and couldn’t really function the way I was used to,” he said. After multiple doctor visits, he was diagnosed with cyclosporiasis and received treatment that cured his infection.
One thing you don’t have to worry about with Cyclospora is person-to-person transmission. If someone in your house develops the bug, you’re highly unlikely to catch it from them, because Cyclospora oocysts, or egg-like structures, have to linger in feces and mature for several days before they can infect you, says Rodrigues. Flushing the toilet takes care of that. However, you could still develop symptoms if you’ve been eating the same food that made that person sick.
The current picture: rising cases
Summer is typically the peak season for this parasite, and Cyclospora cases started increasing in May.
“It happens especially during summertime when people tend to eat more fruits and vegetables, and the organism develops much better and rapidly in warm environments, so that’s when it tends to pick up,” says Rodrigues.
As case counts climb higher than usual this year, the CDC says the true number of infections is likely even greater than what’s been reported. That’s because some people recover at home without seeking medical care, meaning they never received a test to confirm a Cyclospora infection.
Some state health departments are also reporting higher numbers than the CDC because they include both confirmed and probable case counts in their totals. For example, on July 16, the Michigan Department of Health and Human Services reported that they’ve recorded 4,312 cyclosporiasis infections so far in the state.
Whichever way you slice the numbers, experts agree that these case counts are far above typical levels.
Why pinpointing a source is hard
It’s been frustrating to wait for information about the source of the outbreak, but it helps to understand why it’s challenging for experts to find the culprit. For one, Cyclospora’s long incubation period makes the source of infection hard to trace.
Here’s the timeline: First, fecal matter containing Cyclospora infiltrates food, perhaps through contaminated water or soil. Next, the Cyclospora oocysts must mature for seven to ten days before they become infectious. Then, once a person eats food contaminated with Cyclospora, they don’t get sick immediately.
“Typically for something like diarrhea or food poisoning, you'll eat something, and then you'll get sick almost right after, from a couple hours to maybe like a day or two,” says Brown. “But this one's a little different because the time from exposure to getting the symptoms—explosive diarrhea—is about 10 days.”
The CDC reports that it can take anywhere from two days to two weeks to notice symptoms. From there, a person might feel sick for days or weeks before seeing a doctor, if they do at all. If they eventually get checked for cyclosporiasis with a stool test, the results take a few days to come back.
Now imagine you’re that person with a confirmed case of cyclosporiasis, and a public health investigator calls you. Would you be able to remember everything you ate a few weeks ago, along with when and where you bought it? “It's very hard to trace back to the food source, and sometimes the food might not even be available anymore in the market,” says Rodrigues.
Public health teams have quite a mystery on their hands, and they’re already stretched thin, especially during outbreaks. “I think if you ask anyone at a local health department, they would say they were underfunded,” said Kali Kniel, Ph.D., professor of microbial food safety at the University of Delaware.
Even when a particular food comes under suspicion, testing that food directly for Cyclospora can be difficult. Compared to some other contaminants, such as bacteria, Cyclospora is much more challenging to isolate from food and culture under laboratory conditions, says Kniel.
“The best thing to do is try to prevent those contamination events from happening because it is so difficult to sample and test for something like Cyclospora,” Kniel says.
One example: Farms and packing facilities should prioritize clean bathrooms and handwashing stations for workers to reduce the chances that Cyclospora oocysts make their way onto harvest equipment or conveyor belts, Kniel says. Fecal contamination can happen fast.
“When we talk about contamination with human feces, we're not talking about a diaper exploding or someone who didn't wash their hands at all,” Kniel says. “We're talking about microscopic contamination events that just get these oocyst places, or sewage leaks, or rain events that move contaminated water and soil closer to fields or water systems that are then used to irrigate agriculture like lettuce.”
How to reduce your risk of cyclosporiasis at home
While Cyclospora sounds highly unpleasant, and even a bit scary, it’s important to keep the risk in perspective.
“We eat so much fresh produce in the U.S., and the majority of it is not contaminated,” says Kniel. “We are really lucky that we have good growers and we have good systems in place.”
However, a few simple steps could be worth the effort right now to reduce your and your family’s odds of getting sick, especially for anyone with an elevated risk of dehydration, a weakened immune system, and infants, young kids, or elderly people. Experts recommend the following:
- Wash produce under clean running water. “It's probably a good bet if you don't have a lot of cases in your state that your fresh produce is very safe or very low risk, but still, wash it,” says Kniel. Rinsing won’t kill or fully eliminate the parasite, but it can remove some of it. And no, you should not use cleaning products to wash produce. That’s a hard no, says Rodrigues. “It might not be food grade, so they might be adding another hazard, a chemical hazard, to their food,” she says. Stick with running tap water.
- Peel your produce (even lettuce). Remove and discard the outer surfaces where parasites are most likely to nestle. Kniel recommends opting for a head of lettuce instead of bagged lettuce, peeling and discarding the outer leaves, and then washing your hands before proceeding to your next meal-prep step.
- Cook your produce when possible. You can kill Cyclospora by heating food to 158°F or higher. “Sautéing is a perfect way to use those delicious fresh vegetables this time of year,” says Kniel.
- Re-up your kitchen hygiene. “Look at your own kitchen and make sure that you are as proactive as you can be,” says Kniel. “Wash your hands, clean your counters—maybe this is a good time to give that refrigerator a little bit of a cleanup.” She scrubs down her fridge with soap, water, and paper towels before finishing it off with an all-purpose cleaner.
When to seek medical care if you think you have cyclosporiasis
One loose bowel movement is nothing to panic about. But if you develop diarrhea that feels explosive—like you can’t hold it in—and it lasts for more than a couple of days, Brown recommends seeing a doctor. Ditto if the diarrhea comes back after initially getting better.
“Ask for a simple stool test that could test for viruses, bacteria, and parasites to see what you have, rather than waiting,” he recommends. He wishes he’d asked for a stool test to check for Cyclospora sooner.
If you test positive for cyclosporiasis, your doctor will likely prescribe trimethoprim-sulfamethoxazole, an antibiotic that works against Cyclospora in addition to certain bacteria. If you’re allergic to this class of medications, doctors can prescribe an alternative. Rest and fluids can also aid recovery.
Gillean is a media dietitian with over a decade of experience working with brands through TV, content creation, and consulting. She’s the founder of the What’s for Dinner Club, a resource that provides healthy, easy dinner recipes for busy families. As a mom of 3, she knows how overwhelming it can feel to make your nutrition and priority, so through her work she strives to make nutrition simple and convenient. Gillean is also the co-founder of a media training program called Expert with Influence, with the goal of helping health experts grow in the media space and be a source of reliable, credible nutrition information.
Rachel Lustgarten (she/her), M.S., R.D., C.D.N., is a registered dietitian in clinical practice in New York City. Her primary area of focus is medical nutrition therapy and weight control. Rachel’s passion is sharing her knowledge and expertise of food and nutrition’s role in overall health and wellness. She co-hosts the weekly “Primary Care Medicine” show on SiriusXM Doctor Radio, interviewing expert guests and fielding listener calls and questions about hot topics in health and nutrition. She served as a clinical dietitian at the Comprehensive Weight Control Center at Weill Cornell Medicine and served as an Advisor to the Weill Cornell’s Women’s Nutrition Connection monthly newsletter for 10 years. Rachel received a Master’s degree in Clinical Nutrition from New York University, graduating with honors.
