More Than 1,600 Cases Confirmed in the Growing U.S. Cyclospora Outbreak

– A significant outbreak of cyclosporiasis, a parasitic intestinal illness caused by Cyclospora cayetanensis, is spreading across the United States. Since May 1, 2026, the CDC has confirmed 1,645 cases and is tracking more than 5,100 additional cases under investigation across 34 states. This is dramatically higher than the 249 cases reported nationally over the same period last year. Nine percent of confirmed cases have required hospitalization. No deaths have been reported.

The heaviest case counts are concentrated in Michigan, Ohio, New York, and Illinois, though cases have been reported across more than 30 states. The source of the outbreak is still under active investigation by the CDC and FDA. A common food source is suspected.

What is Cyclospora?

Cyclospora is a microscopic parasite spread through food or water contaminated with infected feces. It is not spread directly from person to person. Outbreaks in the U.S. have historically been linked to contaminated fresh produce, and the peak season runs from May through August each year. Because the illness is often underdiagnosed and underreported, the true number of cases is likely higher than what has been reported.

Symptoms typically begin about one week after exposure, though onset can range from 2 to 14 days. Watch for:

Watery diarrhea, which may be frequent
Loss of appetite, bloating, or nausea
Fatigue or weight loss
Low-grade fever in some cases

Without treatment, symptoms can follow a stop-and-start pattern lasting anywhere from a few days to a month or longer. This relapsing pattern is a hallmark of Cyclospora and distinguishes it from more common stomach bugs.

An important note on diagnosis

Cyclospora requires a special laboratory test that is not included in standard stool panels. If your doctor suspects Cyclospora, they must specifically request the test. If you have prolonged or relapsing diarrhea, mention it explicitly and ask whether Cyclospora testing has been ordered. Treatment with trimethoprim/sulfamethoxazole is effective.

How to protect yourself

Wash all fresh produce thoroughly under clean running water before eating, even if labeled pre-washed
Follow safe food handling practices, particularly with fresh herbs, leafy greens, and berries, which have been linked to past Cyclospora outbreaks
Practice careful hand hygiene, especially before eating and after handling produce
Stay well hydrated if diarrhea develops; oral rehydration solution (ORS) is helpful for maintaining fluid balance

When to seek medical care

If diarrhea persists for more than a few days or keeps returning
If you are unable to keep fluids down
If you show signs of significant fluid loss such as dizziness, decreased urination, or extreme fatigue
High-risk individuals, including pregnant persons, older adults, immunocompromised persons, and those with chronic kidney or heart disease, should seek care promptly rather than waiting

Questions or concerns?

Contact us at TravelBug Health. We are here to help you navigate next steps, including whether testing or treatment is appropriate for you.

Resources: