There’s a tiny parasite working its way through the country’s produce, and it’s having a much bigger year than anyone wanted. Federal officials say cyclospora, a microscopic bug that causes days of watery, uncontrollable diarrhea, has turned up in 31 states since May. State health departments have logged more than 4,000 cases, and the season that runs from May through August is nowhere near done.
The good news, if you can call it that, is nobody has died. The bad news is this thing is spreading faster than usual, the source is a total mystery, and washing your lettuce might not fully save you. Here’s what’s actually going on.
The count already blew past all of last year
As of July 9, the CDC confirmed 843 cases across 31 states. But that federal number is running way behind reality. Officials flat-out admit states are reporting higher counts than the feds have processed, and there are more than 1,500 additional cases still being analyzed. State-level tallies push the real figure past 4,000.
To put that in perspective, the U.S. reported about 2,700 cases in all of 2025. We passed that total in the first half of 2026. So far there have been 86 hospitalizations nationwide. The people getting sick range in age from 5 to 88, with a median age of 44, and 59% are women. Another 343 cases were tied to travel outside the country. Michigan, New York, Ohio, Illinois, and North Carolina are getting hit the hardest.
Michigan is the epicenter, and it isn’t close
One state is carrying most of this outbreak on its back. Michigan reported 2,640 cases since late June, with 44 people hospitalized. For context, Michigan normally sees about 40 to 50 cases in an entire year. This is roughly 50 times the usual load, packed into a few weeks.
Most of it is clustered in the southeast corner of the state: 215 cases in Monroe County, 160 in Wayne County, and 159 in Washtenaw County. In all, 43 Michigan counties have logged cases. And it’s not the very young or very old getting slammed. Adults aged 30 to 39 make up 285 cases, just over 20% of the total. Right across the border, Ohio has reported at least 361 cases since June 1, with 46 hospitalizations. Officials think Michigan and Ohio may be part of the same “epidemic cluster.”
What this bug actually does to you
The parasite is called Cyclospora cayetanensis. You pick it up by eating food or drinking water that’s been contaminated, and it sets up shop in your small intestine. The hallmark symptom is watery diarrhea that comes on hard and refuses to quit. Add in nausea, fatigue, cramping, and loss of appetite, and you’ve got a truly miserable stretch.
What makes it sneaky is the timeline. Symptoms can show up anywhere from two days to two weeks after you’re exposed, and the illness can drag on for up to six weeks. It’ll sometimes seem to fade, then come roaring back. A Southern California woman who caught it recently described it as the sickest she’d ever been. One silver lining: unlike a lot of stomach bugs, cyclospora doesn’t jump from person to person. If your roommate has it, you’re not going to catch it from sharing a bathroom.
Nobody knows what’s causing it yet
Here’s the frustrating part. Weeks into this, investigators still can’t point to a single food. There are a few reasons why. The parasite sheds into stool intermittently, which means one test can come back clean even when someone is sick, so people may need multiple tests to catch it. By the time a case is confirmed and reported, several weeks have passed since the person actually ate the bad food.
Now imagine trying to remember exactly what you ate three weeks ago. That’s what investigators are up against. They’re interviewing every one of the 2,600-plus Michigan cases, asking people to reconstruct old meals, and digging through restaurant and grocery receipts to build a paper trail. Michigan officials were so worried they scrambled to push out food-handling guidance to home cooks and restaurants over the July 4 weekend. Finding the culprit could take weeks longer, if they ever pin it down.
The usual suspects live in your salad bowl
Even without a confirmed source this year, the pattern from past outbreaks is pretty clear. The leading theory is fresh produce, and previous U.S. outbreaks have been traced to raspberries, basil, cilantro, snow peas, green onions, leafy greens, and bagged salad kits. What do all of those have in common? You eat them raw. There’s no cooking step to knock out the parasite before it hits your plate.
This has happened before. Back in 2013, more than 600 people got sick across several states, and it was eventually linked to imported fresh cilantro and salad mix. That episode exposed how hard it is to trace produce through a modern supply chain, where a single bag of greens can contain ingredients from multiple farms in multiple countries. Investigators are chasing that same complicated trail right now.
How to lower your odds at the grocery store
There’s no need to swear off fruits and vegetables. But a few habits stack the deck in your favor. Wash all fresh produce under running water, even the stuff you’re going to peel. Scrub firm items like melons and cucumbers with a clean produce brush instead of just rinsing them. For lettuce and leafy greens, buy whole heads instead of prewashed bags, peel off the outer two or three leaves, and rinse the rest.
Cooking is what really kills it. Heating food to 158 degrees Fahrenheit wipes out cyclospora, so cook produce when it’s practical. Wash your hands before and after handling anything fresh, and clean your cutting boards and counters too. One honest caveat: officials say washing lowers your risk but won’t completely remove the parasite if the produce was contaminated before it reached the store, because these organisms cling tightly to surfaces. Investigators also suggest steering clear of public swimming pools while this plays out.
Your regular stomach-bug test won’t catch it
This is the part most people don’t realize. If you go to the doctor with bad diarrhea, the standard stool panel they run doesn’t automatically check for cyclospora. It often takes a special order from your physician. So if your symptoms fit and this outbreak is on your radar, speak up and specifically ask whether testing for cyclospora makes sense. Otherwise the test can easily slip through the cracks.
Once it’s diagnosed, doctors typically treat it with antibiotics, which can shorten how long you’re sick. Severe cases that land in the hospital may get IV fluids to fight dehydration. According to a Michigan State infectious disease doctor, a healthy person will usually recover on their own even without medication. But people with weakened immune systems, or those on drugs that suppress the immune system, are strongly urged to get treated. Dehydration is the real thing to watch, especially in summer heat.
This isn’t one giant outbreak, and that matters
It’s tempting to picture one bad shipment of produce poisoning half the country. That’s not what the data shows. The CDC and FDA say there’s no evidence of a single, multistate outbreak connecting all these cases. Instead, they’re chasing several separate clusters that may each have their own food source. California, for example, has logged a small number of cases this year, but state officials say none are tied to the bigger clusters back east.
There’s one more wrinkle worth knowing. As the CDC and FDA run their traceback work, some reporting has raised questions about staffing cuts at the CDC and the money that flows from the agency to state and local health departments. Those departments do the ground-level detective work, the interviews and the receipt-tracing. Fewer hands can mean slower answers. For now, the smartest move is simple: wash everything well, cook what you can, and if you get hit with days of diarrhea that won’t stop, ask your doctor to test for the parasite by name.
