Let’s Talk About Cyclosporiasis
Since May 1, 2026, thousands of people across at least 34 U.S. states have become ill with cyclosporiasis, a diarrheal disease. The CDC has confirmed over 1,600 laboratory-confirmed cases and is investigating thousands more suspected infections, making this an unusually large and geographically widespread event
The exact source has not yet been identified. Investigators believe the outbreak is linked to fresh produce, but they have not been able to pinpoint a single food item, grower, or distributor. The evidence so far suggests there may actually be multiple overlapping outbreaks involving different foods in different regions rather than one contaminated product. Michigan investigators are reportedly focusing particularly on lettuce and bagged salad products. So, in any event, this ain’t over yet.
While more than 140 people have been hospitalized so far, thankfully (at the time of writing this article), no one has died.
What is it?
Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. Unlike bacteria or viruses, it’s a single-celled protozoan parasite.
Where does it come from?
People become infected by eating food or drinking water contaminated with the parasite.
Common culprits include: cilantro, basil, raspberries, lettuce, snow peas, and other fresh produce. It’s particularly associated with fresh foods that aren’t cooked before eating.
Is is Contagious?
Not in the sense that you can get it from another person directly. The parasite needs days to weeks outside the body before it becomes infectious. This is unusual. So messing with an infected person’s feces (if that’s your thing) is unlikely to infect you.
What Are the Symptoms?
About one week after exposure, patients typically report watery diarrhea (ewwww), loss of appetite, weight loss (from the diarrhea, the dehydration, and the not eating), abdominal cramps, bloating, nausea, and fatigue. Many patients also describe profound exhaustion that lasts longer than the diarrhea.
It can last weeks, and sometimes symptoms come and go for months. This distinguishes it from many viral diarrheal illnesses, which are more short-lived.
Diagnosis & Treatment
Here’s the thing. Routine stool examination won’t find it. (Really, though, who’s getting their stool examined routinely?) You have to be actively looking for it to find it. And the lab must use specialized tests to do so. Detection requires microscopy, molecular testing or another method capable of identifying Cyclospora, and clinicians may need to request it specifically..
There is a very effective treatment for it, a drug called Trimethoprim-sulfamethoxazole. Most people improve quite rapidly after taking it. But it’s worth noting that some people cannot take sulfonamides, and equally effective alternatives are limited.
Prevention
Yes, washing your produce takes care of most of it. But that is not likely to remove all Cyclospora. Cooking is what we need to do. Cook your food, people. I, for one, can do without fresh salads until this particular emergency is over. (This is just me being me, and not an official public health recommendation.)
Why Is this so Tricky Epidemiologically?
- Cyclospora is one of the trickiest foodborne pathogens to investigate.
- Since symptoms typically don’t begin until about a week after exposure, so people often can’t remember exactly what they ate.
- Fresh produce is usually consumed or discarded before investigators recognize an outbreak.
- Produce from multiple farms is often mixed during packaging and distribution.
- You have to know what you’re looking for before you find it.
Why is this newsworthy?
Well, it’s one of the largest Cyclospora outbreaks the USA has seen in a while, we don’t know its exact cause, and its complexity is making it hard for investigators to get a handle on it.
But it’s even more interesting politically. Under RFK Jr, The CDC scaled back its surveillance system for foodborne illnesses; routine national Cyclospora reporting was reduced. And FDA inspections of food facilities declined after staffing cuts, raising concerns about oversight of produce.
How Are Canadians Affected?
Well, I am writing from Canada. We are wary of U.S. food imports in general. But this just makes it worse. Historically, Canadian outbreaks have almost always been traced to imported fresh produce rather than produce grown in Canada.
I hear tell of isolated cases here and there, but none of this is official. It’s clear that there is no established linked outbreak currently in Canada.
One thing I’d like to remind people: this is not norovirus or some other kind of viral diarrhea. Because of the points made above, household transmission is quite unlikely. You are most likely to get it from eating contaminated food, not necessarily from contact with other people.
So, just do what I do: curry everything.
