Short Wave - cyclosporiasis-illness-cyclospora-lettuce-taco-bell

Episode Date: July 21, 2026

What’s small, round and could give you explosive diarrhea? Cyclospora parasites. The diarrheal disease they cause is wreaking havoc on thousands this summer in what is the largest known flare up in the U.S. ever. What’s causing it and what can we do about it? NPR’s Joseph Kim joins host Nate Rott to talk about the outbreak – and how to protect yourself and your loved ones.Read more of Joseph’s reporting on cyclosporiasis here. Interested in more science in the news? Email us your question at [e-mail] public media with NPR+ and enjoy perks for over 25 podcasts like this one. It includes perks like bonus episodes, early access, archive access, curated playlists and sponsor-free listening. Learn more at plus.npr.org.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

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Hey there, Shortwavers. I don't know if you've heard, but there is this illness called cyclosporiasis that has been wreaking havoc on thousands of people across the U.S. this summer, as they've likely eaten contaminated produce. Joseph Kim is a science reporting fellow at NPR, and he has been following this story, and he's here to fill us in on all of the details. Hey, Joe. Help me out.

What is cyclosporiasis? So cyclosporiasis is an intestinal infection caused by parasites of the genus psychospora. Okay. They look like the soccer balls. we saw at the World Cup. And when they get inside people's digestive systems, people know. Because the symptoms I show up later include farting, abdominal cramping, and watery, sometimes explosive diarrhea. It's pretty bad. Okay. Yeah, man, if I had any of those symptoms, I would definitely notice them. So that sounds awful. Yeah, does not sound fun. So I talked about it

with Dr. Rebecca Wirtz. She's a professor at the University of Minnesota School of Public Health and an infectious disease physician. She worked on the first known outbreak in the U.S. in 1990 at Cook County Hospital's dormitory in Illinois. Doctors who were helping to staff the hospital all within the space of a couple days getting sick with a serious diarrhea, and tests were done that showed no known cause of diarrhea, and it took some days, even weeks, for people to look then for a parasitic cause of diarrhea.

diarrhea. And at that same time, those doctors were sick and they were unable to work that summer at the hospital. And all of them recovered, fortunately. Man, I'm glad to hear that they all recovered, but that sounds absolutely awful. How bad is the current situation we're experiencing, Joe? As of last week, 1,645 domestic cases have been confirmed by the CDC. And they know they may have over 5,000 more cases they need to verify. Whoa. And Rebecca says we're in the middle of the largest known cyclospora flare in the U.S. ever. Oh, wow. And because we know that the confirmed cases are only the tip of the iceberg, I think we'll end up seeing many thousands of cases.

Boof. Okay, so today on the show, what you need to know about these cases of explosive diarrhea breaking out across the country, and importantly, how you can avoid it. You're listening to Shortwave, the Science Podcast. podcast from NPR. All right, Joe, so do we know what might be causing all of these cyclosporiasis cases? In a word, no. The FDA and CDC link cases from five states to lettuce serve the Taco Bell.

Taco Bell issued a statement July 16th that it took, quote, immediate action to voluntarily remove potentially impacted lettuce from a supplier in select states. They also said in the statement that the lettuce would be removed from the supply chain nationwide and replaced within 24 hours. And so far, 34 states are reporting cases, so it doesn't account for all of them. We do know it's how it's been spread before, because psychosporiasis is actually seasonal.

Oh, wow. There are cases every year, just not at the scale we're seeing right now. So we do know some things about it. It's spread in contaminated water, and so when someone ingests the water or food that's been washed, with that water or grown with that contaminated water, they may ingest the parasite.

In the 1990 outbreak, the culprit was drinking water at the residence dormitory. Beyond that, the CDC notes that previous outbreaks are generally linked to fresh produce. In 2018, it was a salad at McDonald's. Raspberrys, basil, cilantro, snow peas, and lettuce have all been culprits in the past, according to the FDA. Man, I'm picking up a pattern here. It's like these fast food restaurants. Nothing against fast food.

I love it, but McDonald's Taco Bell. Okay, so, like, what can we do? Well, Nate, you want to make sure none of your produce has been recalled by checking the FDA website and wash your hands with soap and water before handling your fruits and veggies. And make sure you wash your produce

with uncontaminated water. Even if the package says it's pre-washed, vinegar and other popular chemical washes don't work. But cooking will kill it. So does this mean, Joe, that we should stop eating fresh fruits and vegetables? Because my kid would love it if we paused the veggies. He never eats him anyway.

Yeah, my brother, too. Yeah, we all have one. It depends on who you talk to. Rebecca Words, the doctor we heard from earlier, would say your kid is onto something, at least this one time. Until this is one's sorted out, I think it's a reasonable plan to avoid eating salads and eating fresh produce. that includes both at home and in restaurants. But I talked to another physician, Kauazar, Talat, who isn't us worried? Me personally, I am, we're still eating berries, we're still eating lettuce, we're still eating greens.

I may have been a little lackadaisical about washing them in the past. I'm much more careful about making sure that I wash them. Every leaf of lettuce is washed well in running water. So Kauzar is an infectious disease doctor and an associate professor at the Johns Hopkins School of Public Health. And she says most healthy adults don't need to worry. The vast majority of people will have a self-limited infection, may never know that they are infected or have a mild case of diarrhea that will go away by itself. All right, nice.

So that means I can probably have my salads and, you know, still try to eat healthy. But now, like, I want to learn about what this bug actually is. Like, can I look at it in its eyes? So it's a small, round parasite. Okay. Only about the length of a red blood cell at its large. or at least that's how they are usually and no eyes. Sorry, Nate. Yeah, okay. So there's no eyes to stare menacingly into. That's a bummer, but, uh, you know, okay, go on. Yeah, no. And when they get into

people's bodies, they invade cells in the small intestines, ravaged through neighboring cells, then reproduce and eventually end up in the toilet, hopefully, and not your pants, Nate. Yeah, well, I'm not going to tell you the story of the last time that happened, Joe, not on this podcast. But this whole thing is giving me the hebi-jeebies. Like, what's treatment like? Can we just kill this parasite if we have it with like an antibiotic or something? Yeah, this is what Rebecca says. There is one antibiotic that can be used, trimetoprim, sulfomythoxysol. It's also called Bactrum or septra, which can be used to limit the symptoms, but that's not used as a routine. It's usually used in people who are a little bit more immunocompromised. And that's because their immune

systems need a bit of extra help. That makes sense. Fun fact, Nate, this antibiotic also works for some other parasites. It works by blocking the bugs for making more DNA. Huh. Yeah, I'm into that. Okay, so there are drugs available that work, but most people won't need them, unless they're, like, really sick or immunocompromised.

Yeah, exactly. Rebecca and Cowsar both say that young, old, and immunocompromise people should be extra cautious and proactive even about getting chivalized. checked up if they're worried. Okay, so is that, you know, if I'm a immunocompromised person or I'm older, is that something that people should be looking out for, like bad diarrhea? Yeah, mostly bad diarrhea. A bad day on the toilet probably isn't something to be worried about, but Kowazar says, if you, diarrhea persists for more than a couple, a few days, see your doctor. If the diarrhea goes away and comes back, that's another sign of potential cyclospora infection, and again,

go see your doctor. Again, for most people, this would show up as some bad trips to the bathroom. And CDC says it can be largely avoided by either limiting your veggie intake temporarily or else washing and cooking fresh produce thoroughly. But I mean, Joe, if this thing might just go away on its own, is it even worth going and seeing a doctor? I hate going to the doctor. Well, it's probably good just to confirm it's actually cyclosporiasis. And going to the doctor, Reporting and getting tested can also mean a lot for public health officials, helping them track down how many cases and possibly pin down the source faster. Also, PSA, if you're experiencing diarrhea, you should drink lots of water to replenish your fluids. So I guess what you're saying there, Joe,

is that it's kind of like a civic duty to go to the doctor then. Yeah. Okay. And then getting treatment is just like a bonus too. You bet. And we've covered a lot of ground in 10 minutes. So Nate, I want to leave you with some optimism. Rebecca says we can hope for a silver lining here. Hopefully the source is identified in this outbreak and it's managed better in the future. Knowing exactly what's causing these cases nationally in so many states could mean that people can get a handle on a situation and hopefully at least get back down to a more regular case count, which is, you know, in the low hundreds instead of the thousands. Well, here's open for that, Joe. I hope that's what we end up that. Yeah, we can go back to our regular amount of diarrhea.

Surewivers, if you like this episode, share it with your parasitic friends. You know who you are. Or your non-parasitic companions. Or you can share it with a buddy who's gotten upset tummy and looking for answers. All of it helps our show. This episode was produced by Burley McCoy, edited by our showrunner, Rebecca Ramirez, and fact-checked by Joe and Tyler Jones. The audio engineer was Onley Warn. I'm Nate Rot and I'm Joseph Kim. Thanks for listening to Shortwave, the science podcast from NPR.