Cyclospora

Cyclospora cayetanensis, or more commonly referred to as Cyclospora, is a microscopic parasite that infects the small intestine and causes cyclosporiasis. Cyclosporiasis is a nationally notifiable disease in the United States. Cases occur every year, with most illnesses reported between May and August. Although Cyclospora was historically associated with travel to tropical and subtropical regions and imported produce, recent outbreaks have increasingly been linked to domestically grown fresh produce.^1,2

Fresh produce identified as vehicles of transmission during outbreaks has included raspberries, basil, snow peas, cilantro, bagged salad mixes, and romaine lettuce. In 2018, multiple outbreaks were linked to romaine lettuce produced in the United States, marking an important shift from previous outbreaks associated primarily with imported produce.^1,2

Cyclospora continues to be a significant produce safety concern. US FDA and US CDC investigations have identified recurring seasonal outbreaks associated with fresh produce, and in recent years several thousand domestically acquired cases have been reported in the United States. In 2026, CDC reported 145 domestically acquired cases across 17 states by mid-June, highlighting the ongoing public health importance of this parasite.^1,2

Symptoms typically begin about one week after exposure but can range anywhere from two days to two weeks. Common symptoms include:

• Watery diarrhea, sometimes explosive
• Loss of appetite
• Weight loss
• Abdominal cramping and bloating
• Nausea
• Fatigue
• Low-grade fever and vomiting (less common)

Without treatment, illness may persist for several weeks or longer and can follow a relapsing-remitting pattern.⁴

Cyclospora is spread through ingestion of food or water contaminated with human feces containing infective oocysts. Person-to-person transmission is unlikely because oocysts shed in feces are not immediately infectious.

After shedding, oocysts typically require 1–2 weeks in the environment to sporulate and become infectious.^3,4

1. US Food & Drug Administration (FDA). Cyclospora Prevention, Response and Research Action Plan. (2021, July 1). [FDA.gov – Action Plan]
2. US Centers for Disease Control and Prevention (CDC). Surveillance of Cyclosporiasis. (2026, July 1). [CDC.gov – Surveillance]
3. US Food & Drug Administration (FDA). Cyclosporiasis and Fresh Produce: An Overview of Cyclospora cayetanensis for Farmers. (2022, July). [FDA.gov – Fresh Produce]
4. US Centers for Disease Control and Prevention (CDC). Clinical Overview of Cyclosporiasis. (2024, March 4). [CDC.gov – Overview]
5. US Centers for Disease Control and Prevention (CDC). Preventing Cyclosporiasis. (2024, February 29). [CDC.gov – Prevention]
6. Hall R.L., Jones J.L., Herwaldt B.L. Surveillance for laboratory-confirmed sporadic cases of cyclosporiasis—United States, 1997–2008. MMWR. 2011;60(2):1–11.