Cyclosporiasis

This week we talk about cyclospora, FoodNet, and Taylor Farms.

We also discuss iceberg lettuce, Taco Bell, and foodborne pathogens.

Recommended Book: Babel by R.F. Kuang

Transcript

Foodborne pathogens cause about 48 million illnesses and around 3000 deaths in the US alone each year.

The Centers for Disease Control and Prevention is the main agency tasked with keeping those numbers as low as possible, and the CDC’s Foodborne Diseases Active Surveillance Network, or FoodNet, is one way that they’ve tackled this pernicious, persistent problem since 1995, in partnership with the Food and Drug Administration, the US Department of Agriculture, and 10 state health departments: those of California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee.

Collectively, this FoodNet network covers about 16% of the US population, which seems like a small number, and in some ways it is, but that grid of laboratories and surveillance sites has typically been capable of detecting foodborne problems before they’ve scaled-up into something more significant, growing from a localized issue into a nationwide outbreak. They’re generally not capable of preventing them outright, but they can keep them relatively small and regionalized.

FoodNet was created in response to a series of huge, deadly E. coli outbreaks in 1992 and 1993, and in contrast to other common methods of detection, which are usually passive and thus a little slow to respond to potential outbreak indicators, this program was built around active surveillance methods, which means proactively gathering data from medical treatment records, hospitalizations, and even individual patient outcomes (including their travel history)—anything they can pair with diagnostic samples to better understand the context surrounding the products that contain dangerous pathogens—and this was intended to help them move faster to identify issues, triangulate the source of those issues, and then implement measures to solve these issues before they harm a bunch of people, as happened during another round of E. coli outbreaks in 2012 and 2013, which sickened dozens of people across multiple states, about half of the afflicted requiring hospitalization, in addition to at least one known death.

At its height, FoodNet tracked 9 pathogens, so it cast a pretty broad net, encompassing the most common and dangerous of these potential vectors, including listeria, campylobacter, shigella, vibrio, yersinia, cyclospora, cryptosporidium, e coli, and salmonella.

In July of 2025, as part of a larger wave of sweeping cuts across the nation’s safety nets, tracking systems, and scientific agencies, the CDC, under the second Trump administration, downgraded FoodNet so that it was only mandatory to track salmonella and E coli—the rest were no longer on the docket, because these agencies no longer had the budget to keep tracking them.

What I’d like to talk about today is a recent, and as of the day I’m recording this ongoing, outbreak of cyclospora-induced cyclosporiasis, what we know about this outbreak, and what might happen next.

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Cyclospora cayetanensis is a protozoan that can infect human beings, and which is usually transmitted via contaminated fruits and vegetables. This contamination is typically the consequence of inadequate sanitation standards, as it’s not transmitted via coughing or blood or anything like that, it’s carried via human feces.

So this parasite gets into a human, sporulates, which means it releases a bunch of spores within its host, and then usually between 1 and 2 weeks after entering its new host, the host develops cyclosporiasis, the disease caused by cyclospora producing all those spores. This disease is notorious for sometimes causing what’s colorfully called explosive diarrhea, alongside general watery bowel movements, intense cramping and severe gas and bloating, and that’s sometimes paired with nausea, vomiting, fever, and dehydration, due to all the frequent, intense, watery bowel-movement-related output.

This is how cyclospora reproduces and spreads: it infects a host, that host has urgent diarrhea for a while, usually more than two days, sometimes as long as several weeks or even a month or more, with all the pain and discomfort and life-disrupting issues you might assume from that sort of persistent symptom, and then it sometimes finds new hosts via that watery output.

Sometimes, cyclospora works its way into food systems because sanitation standards at a particular farm will be not good. Specifically, workers will sometimes not be allowed to take restroom breaks, and they’ll simply do their business right there in the field; so if they’re sick and can’t afford to take a sick day, and might be fired if they do, or if they’re asymptomatic, which some people infected with cyclospora are, they might do their business in the field, unaware that waste can then go on to spread this pathogen into the food system. It’s also possible that someone just doesn’t wash their hands properly after using the rest room, and then gets back to work, picking vegetables or operating at some other level along the food processing and packaging assembly line, and it gets into the system that way.

In a typical year, the United States records around 2,700 confirmed cases of cyclosporiasis, though on occasion it’s as low as just a few hundred cases, the majority of which show up in health records in the Spring and Summer, between May and August. That range includes relatively mild outbreaks, so while this is a persistent issue, it’s also not generally a massive one, at least compared to other pathogens of note. It’s not pleasant for those who come down with it, of course, but not something that has triggered an organized response from the top, because of its meager scale, and because (again, while super unpleasant) people with healthy immune systems generally recover without treatment, even if that recovery can take a while. The biggest risk for most people who catch this disease is dehydration, though immunocompromised people are also sometimes given antibiotics by their doctors, the typical dosage curing about 96% of the people who receive it.

There was a larger-than-usual outbreak of cyclosporiasis in the US in 2020, which caused a confirmed 1,241 cases across the country, a whole lot to land all at once, and there were no reported deaths resulting from that outbreak. Between 2018 and 2021, there were about 6,000 total confirmed cases across the US, so an average of about 2000 per year.

As of mid-July 2026, the CDC has officially confirmed 1,645 cases of this illness, with another 5,100 probable or potential cases currently under investigation. If the majority of those still-under-investigation cases are confirmed, that would mean more people have already been infected as a result of this one outbreak in the first half of 2026 than were infected between 2018 and 2021, which again, is a range that includes the large outbreak that happened in 2020.

Also worth noting about those numbers: that’s federal-level, CDC reporting, and it’s generally understood that there’s a significant lag between local-level data and those that have percolated up to the national level. As of the day I’m recording this, Michigan’s health agencies alone have more than 5,000 confirmed and suspected cases, Ohio has nearly 1,200, and other states, which are still investigating, are seeing dozens of confirmed cases, including 43 in Wisconsin, 69 in Maryland, and a few already, in the early stages of investigation, in Nevada.

Over the past week, officials flagged shredded lettuce sourced from Mexico and sold by a company called Taylor Farms as the likely source of at least some of these cases, and that’s led to a recall on lettuce produced by the company in 27 states. Over the weekend, the CDC found cyclospora in iceberg lettuce from the company’s Mexican operations, as well, and this lettuce was part of a batch that wasn’t included in the recall—so there’s a good chance the recall will expand beyond the currently targeted products, which include shredded lettuce destined for Taco Bell locations in five states, and the kitchens of several other fast food chains, as well.

Taylor Farms is one of the largest producers of fresh fruits and vegetables in the United States, and their products are sold all over the place, from lower-end fast food restaurants to more expensive grocery stores like Whole Foods.

Taylor Foods has announced that it’s voluntarily removing all iceberg lettuce sourced from central Mexico from shelves, even though none of its branded, in-store salad kits have been clearly tied to the outbreak, and Taco Bell has said that it’s voluntarily removing all potentially affected lettuce from its locations in the five most-impacted states, indefinitely removing lettuce sourced from the implicated supplier; other brands are following suit, no one wanting to be associated with this outbreak, but everyone wanting to show would-be customers that they’re taking it seriously.

Interestingly, the FDA doesn’t actually require that Taylor Foods tell the public who their products go to—which other entities might be selling infected produce. So they’ve released lists of product numbers, and again, many of their customers are taking the initiative to announce the removal of this lettuce from their shelves or food, without being prompted, but there’s still some fog-of-war here, because of Taylor Foods’ decision not to be clearer with that product list.

So this is already the largest recorded cyclospora outbreak in US history, there have been 141 confirmed hospitalizations from the CDC, and that number is likely larger, again because it takes a while for state-level numbers to work their way up to the CDC, and to be reconfirmed at that level. Also important to note here is that a lot, perhaps even the majority of people who suffer from cyclosporiasis will never show up in these data, because they just suffer silently, either not realizing they have this parasite, or not seeing the point of going to the hospital, maybe paying an arm and a leg to do so, just to get prescribed anti-diarrheal medication and told to take fluids, same as they can do at home. People who do have any kind of immunodeficiency issues or potentially confounding factors, like being older or very young, are being encouraged to seek medical help, though, as they’re more likely to suffer more serious consequences after contracting this disease.

It’s currently unclear where precisely this outbreak came from, and it’s puzzling how an outbreak of this scale might have happened, as, in the words of Matthew Moore, a food safety microbiologist at the University of Massachusetts Amherst who was quoted in the New York Times, this many infections suggest there was a “massive degree of human fecal contamination.” So probably not just a farm laborer who forgot to wash their hands after using the rest room, something much more substantial than that.

Also, because cyclospora takes a while, a week or two, to create enough spores in its host to trigger cyclosporiasis, attribution of the infection difficult, which in turn makes tracking it back to its source difficult; which is part of why this outbreak, which has been going on for weeks, is still under investigation, not a solved problem with definitive answers and in-practice solutions.

Right now, experts are recommending higher-risk foods are cooked to at least 158 degrees F, because that temperature kills this pathogen, and washing fresh produce doesn’t always get rid of all the cyclospora on a contaminated piece of produce. Washing fresh produce certainly helps, and it’s better than nothing, and scrubbing is even better. They also recommend avoiding high-risk foods when possible, though of course that won’t always be possible for everyone, nor will it always be possible to get heads of lettuce rather than pre-made salads, though that’s also advised when feasible.

Also worth noting here is that even if the FoodNet program was still up to full power, tracking all 9 of those original pathogens, it’s unlikely this outbreak would have been prevented.

It likely would have flagged that something was up earlier on in this outbreak, though, which could have led to faster action in the afflicted regions. It probably would have allowed professionals to note hot spots faster, as well, which is what this kind of surveillance system is for: it doesn’t prevent, but it does make it more likely experts will have the chance to keep things from spiraling out of control.

Show Notes

https://www.nytimes.com/2026/07/16/well/cyclospora-taylor-farms-lettuce-taco-bell.html

https://www.nytimes.com/2026/07/15/well/eat/cyclospora-stomach-bug-what-to-know.html

https://www.nytimes.com/2026/07/17/business/cyclospora-taylor-farms-lettuce.html

https://www.nytimes.com/2026/07/17/well/eat/lettuce-safety-cyclospora-outbreak.html

https://www.nytimes.com/2026/07/17/health/cyclospora-taylor-farms-mexico-taco-bell-lettuce.html

https://en.wikipedia.org/wiki/Cyclosporiasis

https://pmc.ncbi.nlm.nih.gov/articles/PMC8471761/

https://journals.sagepub.com/doi/10.1177/00494755261437456

https://www.theguardian.com/commentisfree/2026/jul/16/diarrhea-outbreak-cyclospora-parasite-cdc

https://www.cdc.gov/cyclosporiasis/php/surveillance/index.html

https://www.hopkinsmedicine.org/health/expert-qa/cyclosporiasis-outbreak

https://www.forbes.com/sites/maryroeloffs/2026/07/17/taco-bell-warned-investors-about-cyclospora-before-the-outbreak-and-these-other-chains-did-too/

https://www.today.com/health/disease/cyclosporiasis-outbreak-foods-avoid-map-cases-parasite-diarrhea-2026-rcna588006

http://cnn.com/2026/07/18/health/cyclospora-what-to-do-wellness

https://www.statnews.com/2025/12/22/american-food-safety-funding-cuts-foodnet/

https://www.cidrap.umn.edu/foodborne-disease/cdc-cuts-back-foodborne-illness-surveillance-program

https://www.nbcnews.com/health/health-news/cdc-quietly-scaled-back-surveillance-program-foodborne-illnesses-rcna227089

https://www.thelancet.com/journals/langas/article/PIIS2468-1253(25)00305-X/fulltext

https://www.cdc.gov/foodnet/about/index.html

https://www.food-safety.com/articles/10646-cdc-slashes-foodnet-surveillance-from-eight-foodborne-pathogens-to-two

https://www.thermofisher.com/blog/food/foodnet-active-surveillance-for-food-safety/

https://www.nytimes.com/2026/07/18/health/taylor-farms-iceberg-lettuce-recall.html

https://apnews.com/article/cyclospora-lettuce-recall-taylor-farms-taco-bell-8c8bb30fbd100e0c246cffeff6983753

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