The United States is experiencing a record-breaking cyclospora outbreak, with nearly 18,000 confirmed or probable cases reported across 45 states since May 2026, compared to the typical annual average of 3,000 cases. The parasitic infection, which causes severe intestinal distress, has hospitalized at least 423 people nationwide, though no deaths have been reported so far.

What Is Cyclospora and How Does It Spread?

Cyclospora cayetanensis is a microscopic parasite that lives in human feces and infects the small intestine when people consume contaminated food or water. The hallmark symptom is watery, sometimes "explosive" diarrhea, along with abdominal cramping, bloating, appetite loss, and fatigue. If left untreated, the infection can last for weeks, though it is rarely life-threatening.

"People become infected with cyclospora by consuming food or water contaminated with particles of feces from an infected person," explained Kali Kniel, Ph.D., professor of microbial food safety at the University of Delaware.

Kali Kniel, Ph.D., Professor of Microbial Food Safety at the University of Delaware

The parasite gets into produce when crops are grown in contaminated soil or washed with contaminated water. Fresh fruits and vegetables are the most common culprits. Importantly, person-to-person spread is very unlikely because the parasite takes one to two weeks to mature and become infectious after leaving the body.

Which States Are Being Hit Hardest by This Outbreak?

Michigan is experiencing the most severe impact, with 10,077 reported cases and 160 hospitalizations as of late July. A massive multistate outbreak initially affected five Midwest states, Indiana, Kentucky, Ohio, Michigan, and West Virginia, but has since expanded to nine states total.

• Michigan: 10,077 cases and 160 hospitalizations, the hardest-hit state in the nation
• Ohio: Over 2,500 reported cases of cyclosporiasis
• Indiana and Illinois: Each state nearing 600 cases
• Missouri, New York, and North Carolina: Case counts surpassing 200 in each state
• Kansas, Oklahoma, and Pennsylvania: Additional states included in the nine-state outbreak

Beyond these nine states, the Centers for Disease Control and Prevention (CDC) is investigating five smaller cyclospora outbreaks in other parts of the country, though specific locations have not been disclosed. The true number of infections is likely much higher because many people recover on their own without getting tested.

What Food Sources Have Been Linked to the Outbreak?

The U.S. Food and Drug Administration (FDA) and CDC have identified shredded iceberg lettuce served at Taco Bell as a potential source in the nine-state outbreak. After interviewing over 1,900 sickened people who reported eating at Taco Bell in June or July, health officials traced the contamination to Taylor Farms, the lettuce supplier. The company has issued a voluntary recall of all iceberg lettuce products sourced from central Mexico.

However, investigators suspect multiple food sources may be driving cases nationwide. Officials in North Carolina have indicated that fresh parsley and cilantro may be behind the increase in cases in that state, which has surpassed 700 cases. Past cyclospora outbreaks in the United States have been linked to salad greens, cilantro, basil, raspberries, green onions, and snow peas.

"There may be multiple unrelated outbreaks going on at the same time," noted Donald Schaffner, Ph.D., professor of food microbiology in the Department of Food Science at Rutgers University.

Donald Schaffner, Ph.D., Professor of Food Microbiology at Rutgers University

Why Is Cyclospora So Difficult to Track and Investigate?

Cyclospora presents unique challenges for food safety investigators. The incubation period is long, with symptoms potentially not appearing for up to 14 days after exposure. By the time a person is tested, diagnosed, and interviewed by an epidemiologist, weeks may have passed, making it difficult for them to remember what they ate. As a result, only a small fraction of cyclospora cases each year get traced back to a specific food item.

Additionally, in July 2025, the CDC's foodborne surveillance network made testing for cyclospora optional, a change that some food safety experts believe could be impacting the investigation and response efforts. Federal health authorities have denied that changes to surveillance are affecting the outbreak response.

How to Protect Yourself During Peak Produce Season

• Avoid recalled products: Do not consume Taylor Farms iceberg lettuce or shredded lettuce with best-if-used-by dates between July 18 and August 3, 2026, which were distributed to 27 states
• Ask about lettuce sources: When ordering salads at restaurants, ask where the iceberg lettuce was sourced before consuming it
• Stay informed on investigations: Monitor FDA and CDC updates for additional implicated brands, restaurants, retailers, or distribution channels that may be identified as the outbreak continues
• Seek treatment promptly: If you experience severe watery diarrhea, abdominal cramping, or other gastrointestinal symptoms, consult a healthcare provider, as doctors can treat cyclospora with combination antibiotics

The CDC anticipates that cases will continue to increase, possibly through the end of August. Health authorities emphasize that investigations are ongoing and additional food sources may be identified in the coming weeks.