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By Anna Skinner
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Americans are grappling with an unusually severe cyclospora season as thousands of illnesses continue to be reported across the country and health officials race to identify contaminated foods behind multiple outbreaks.
The Centers for Disease Control and Prevention (CDC) said this week it has received reports of 4,173 laboratory-confirmed domestic cases since May 1 and is aware of thousands more illnesses still under review, making 2026 the largest cyclospora season on record.
As case numbers climb, many people are asking the same questions: How dangerous is cyclospora? When should you seek medical care? And can the parasite actually be fatal?
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Doctors say most people recover fully with proper treatment, but the illness can still cause significant complications—particularly when diagnosis is delayed, or severe dehydration develops.
The Latest on the Cyclospora Outbreak in the US
Cyclospora is a microscopic parasite that causes cyclosporiasis, an intestinal illness characterized by prolonged watery and explosive diarrhea, stomach cramps, fatigue and loss of appetite. Cases traditionally rise during the spring and summer months, but health officials have reported a much larger-than-normal surge this year.
Federal investigators are currently examining multiple outbreaks and have linked one large multistate outbreak to iceberg lettuce sourced from central Mexico. On July 17, Taylor Farms recalled certain iceberg lettuce products as part of the investigation.
The CDC reported 4,173 confirmed cyclospora cases with 7,400 additional cases that have not yet been confirmed. Of the confirmed cases, 308 people have been hospitalized, roughly 7.38 percent. No deaths have been reported.
State officials report much higher cyclospora case numbers.
For example, Michigan has reported 7,664 cyclospora cases, with 160 hospitalizations, or 2.08 percent of cases. In Oklahoma, out of 172 reported cases, 12 people have been hospitalized, or 6.97 percent. In Ohio, out of 1,300 cases, 96 people have been hospitalized, or 7.38 percent.
Health officials caution that the hospitalization figure likely overstates the risk for the average infected person because many mild infections are never formally diagnosed.
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Where Does Cyclospora Come From? Why Officials Still Don't Know
Cyclospora cayetanensis is a parasite that originates from human fecal contamination. People become infected after consuming contaminated food or water, particularly fresh produce that is eaten raw. Previous U.S. outbreaks have been linked to foods including cilantro, basil, berries and leafy greens.
The parasite is unusual because it generally does not spread directly from one person to another. After leaving the body, it must spend time in the environment before becoming infectious.
Although investigators have identified one lettuce-linked outbreak, officials say that does not explain every illness reported this year. Multiple clusters remain under investigation, and the U.S. Food and Drug Administration (FDA) has said it continues searching for additional contaminated products that may be contributing to cases. In North Carolina, in addition to lettuce, parsley and cilantro are top suspects.
What Symptoms Come With Cyclospora, and How Do You Treat Them?
Symptoms typically begin about a week after exposure, although they can appear anywhere from two days to two weeks later. The most common symptom is watery diarrhea, which may occur frequently and, in some cases, become severe. Other symptoms include stomach cramps, bloating, nausea, weight loss, fatigue and loss of appetite.
Without treatment, symptoms can linger for weeks and may improve before returning again.
The standard treatment is the antibiotic trimethoprim-sulfamethoxazole, often sold under the brand name Bactrim. Hydration is also an important part of recovery because prolonged diarrhea can result in substantial fluid loss.
According to physicians, many patients improve quickly once the infection is correctly identified and treated.
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Does Cyclospora Go Away on Its Own? When to Seek Medical Attention
Some cyclospora infections eventually resolve without treatment, but experts say patients should not assume the parasite will simply disappear on its own.
Dr. Tyler Evans, CEO and founder of Wellness Equity Alliance, told Newsweek that one of the biggest challenges is that cyclospora is often overlooked during testing.
"The people most at risk of staying sick are the ones whose clinician never orders the test," he said. "Cyclospora does not show up on a standard stool panel. A clinician has to specifically ask for it."
Evans said the greatest immediate threat isn't usually the parasite itself but the consequences of ongoing diarrhea.
"What sends someone to the hospital is usually not the parasite itself. It is dehydration," he said. "This illness causes prolonged watery diarrhea, and prolonged fluid loss is what damages kidneys and disrupts electrolytes."
Experts recommend seeking medical attention for persistent diarrhea, signs of dehydration such as dizziness or decreased urination, ongoing vomiting, worsening symptoms, or symptoms that fail to improve over time. People with weakened immune systems should also contact a health care provider promptly if symptoms develop.
Can You Die From Cyclospora? What To Know
Experts say death from the parasite is exceedingly rare.
"There have been no deaths in this outbreak," Evans told Newsweek. "For most healthy people, this is a miserable illness, not a dangerous one."
CDC data supports that assessment. Despite thousands of reported cases nationwide, health authorities have not reported any deaths associated with the current outbreak.
Evans said patients who are immunocompromised—including people living with HIV, transplant recipients and those undergoing cancer treatment—face a greater risk of prolonged or more severe disease. Even so, he emphasized that cyclospora is generally considered treatable rather than life-threatening.
"I would not tell the public this is life-threatening," he said. "I would tell them it is treatable. The danger comes from letting it go untreated for weeks because nobody ordered the right test."
For most patients, doctors say the best course of action is straightforward: stay hydrated, seek medical care if symptoms persist, and ask about cyclospora testing if severe diarrhea continues without a clear explanation. Early diagnosis and treatment remain the most effective tools for preventing complications.
Cyclosporiasis Outbreak
Check out Newsweek's latest coverage:
- Taylor Farms Says FDA Has Apologized Over ‘False Positive’ Cyclospora Test
- Cyclospora Patient Reveals What Symptoms are Really Like as Outbreak Spreads
- Which Salad Greens Are Safe From Cyclospora Parasite? List of Companies, Where to Buy
- What Kills Cyclospora? Food Safety Tips Amid Explosive Diarrhea Outbreaks
- Medicine To Treat ‘Explosive’ Diarrhea Outbreaks Could Cause More Diarrhea
- Cyclospora Isn’t the Only Parasite in Fresh Produce—Experts Warn of Others
- How Long Does Cyclospora Incubate? Symptoms To Watch For, How to Treat It
- Where Does Cyclospora Parasite Come From? How to Protect Yourself
Contact Newsweek editors on this story: Jason Lemon and Sam Wilson.
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