What You Need to Know About Cyclospora, the Parasite That Has Sent Nearly 7,000 Americans to the Bathroom

You might have seen it all over your feed. Jokes and panic over an “explosive diarrhea” epidemic in the country. And it’s not fake news.

The summer of 2026 has produced a record-breaking outbreak of a diarrhea-causing parasite, and federal health officials are still working to contain it. Nearly 7,000 Americans have been infected with cyclospora nationwide. The outbreak has spread to more than 30 states and already surpassed the previous U.S. record of roughly 4,700 cases set in 2019, per the AP.

Here is what you need to know.

What Is Cyclospora?

Cyclospora cayetanensis is a microscopic, spherical parasite that infects the bowels and spreads through feces, per the Centers for Disease Control and Prevention. It causes a condition called cyclosporiasis, which the CDC describes as producing watery diarrhea “with frequent and sometimes explosive bowel movements.” The illness also causes cramping, bloating, increased gas, nausea, loss of appetite, weight loss, and fatigue.

Symptoms typically appear about one week after infection, though they can take anywhere from two days to two weeks or more to present. Without antibiotic treatment, symptoms can last from a few days to a month or longer. The illness is rarely life-threatening and is generally treatable.

The parasite thrives in warm conditions and tends to spike in late spring and summer. It spreads when people eat food or drink water contaminated with feces, which can infiltrate large commercial farms through poor labor conditions, fertilizers, runoff from meat and poultry plants, or polluted waterways, per CNN.

How Large Is the Cyclospora Outbreak?

The outbreak is the largest the country has seen in years. Nearly 7,000 Americans have been infected nationwide. Michigan has been hit hardest, with more than 4,000 suspected cases. It is the largest cyclospora outbreak in state history. Indiana, Kentucky, Ohio, and West Virginia have also confirmed cases, as infections first appeared in early May and have since spread to more than 30 states.

Federal investigators have traced more than 1,644 of those cases to shredded iceberg lettuce from Mexico, supplied to a national fast-food chain in those five states, per the FDA and CDC. Investigators have identified a single supplier and are working to determine whether contaminated lettuce from that source also reached other restaurants, retailers, or distribution channels. Ninety-four people have been hospitalized. No deaths have been reported.

What to Watch For

The primary symptoms of cyclosporiasis include watery diarrhea, fatigue, and loss of appetite. Additional symptoms include cramping, bloating, increased gas, nausea, and weight loss. People who develop these symptoms and believe they may have eaten contaminated food should contact their healthcare provider and specifically request testing for Cyclospora. Routine stool tests do not screen for it.

Symptoms can take up to two weeks or longer to appear. Staying well-hydrated is important if you become ill.

How to Protect Yourself From Cyclospora

Alcohol-based hand sanitizers do not kill cyclospora and are not a substitute for handwashing. Dr. Erika Noel, an assistant professor at Hawaii’s medical school, recommends washing hands thoroughly with soap and water before handling food.

For produce, the AP recommends submerging fruits and vegetables in a solution of three parts water and one part vinegar, swishing for a few minutes, then rinsing. The soak helps remove the parasite from produce surfaces, but will not kill it. Cooking produce to an internal temperature of 158 degrees Fahrenheit (70 degrees Celsius) kills cyclospora entirely, per the CDC.

Additional steps you can take: choose a whole head of lettuce and remove the outer layer rather than buying pre-mixed bags. Peel fruits and vegetables when possible. Consider frozen produce as an alternative to fresh.

What Made This Outbreak Possible

Experts attribute the rise in cyclospora cases to climate change, which extends the parasite’s warm-weather active season, and improved detection methods. Cases went historically underreported because common foodborne illness tests do not screen for cyclospora.

The current outbreak is unfolding against a specific policy backdrop. In 2025, the CDC made tracking cyclospora and other foodborne illnesses optional, retaining mandatory surveillance only for Salmonella and E. coli. Connecticut Democratic Congresswoman Rosa DeLauro connected that decision directly to the current outbreak: “Outbreaks like this, and possibly worse, will happen again and again until we change course,” she said.

The food system itself helps explain how an outbreak like this spreads so far. Large commercial farms often pay workers per unit of harvest, which discourages bathroom breaks or staying home when sick, per Jeff Stainthorp, owner of a small farm in Washington state. Cyclospora is notoriously difficult to trace. “This isn’t like detecting a needle in a haystack,” said Steven Manderach, executive director of the Association of Food and Drug Officials, per the BBC. “It’s like detecting a microscopic portion of a needle in a haystack.”

The investigation remains open.