The Centers for Disease Control and Prevention says more than 11,500 cases of cyclosporiasis, an intestinal illness caused by a microscopic parasite, have been reported across 41 states so far this year. The agency disclosed the tally this week as part of its ongoing seasonal surveillance of the disease, which typically spikes each summer in the United States.
Cyclosporiasis is caused by Cyclospora cayetanensis, a single-celled parasite that spreads when people ingest food or water contaminated with infected fecal matter. The illness has historically been tied to imported and domestic fresh produce, including basil, cilantro, leafy greens, snap peas and berries, though health officials say they have not yet confirmed a single common source behind this year’s surge.
What Is Cyclosporiasis?
The CDC describes cyclosporiasis as an intestinal infection that produces watery diarrhea, often accompanied by loss of appetite, weight loss, cramping, bloating, increased gas, nausea and fatigue. Unlike many foodborne illnesses that resolve within days, cyclosporiasis symptoms can persist for weeks or even months if left untreated, and infected individuals may experience relapses.
Symptoms usually appear about a week after exposure, though the incubation period can range from two days to two weeks. The parasite is not spread through casual person-to-person contact the way viral illnesses like norovirus are, because the Cyclospora oocysts shed in feces need days to weeks outside a host to become infectious.
Where Cases Are Concentrated
The CDC has not named specific states topping the case count in its latest update, but agency data shows cyclosporiasis cases have historically clustered in states with large populations and heavy fresh produce distribution networks, including Texas, Florida, New York and states across the Midwest. The disease is nationally notifiable, meaning state and local health departments are required to report confirmed cases to the CDC, which helps investigators track outbreaks in near real time.
Because the parasite is often linked to imported produce during the U.S. off-season for certain crops, investigators from the CDC, the Food and Drug Administration and the U.S. Department of Agriculture routinely coordinate on traceback investigations when case clusters emerge. Those investigations involve interviewing sick patients about what they ate in the weeks before symptoms began, then working backward through supply chains to identify farms, distributors or processing facilities that multiple patients have in common.
Health officials emphasize that identifying a specific food vehicle in a Cyclospora outbreak can take weeks, since the parasite has a long incubation period and patients often cannot recall every meal they ate during that window.
Treatment and Who’s at Risk
Cyclosporiasis is typically treated with a course of the antibiotic combination trimethoprim-sulfamethoxazole, commonly sold under brand names such as Bactrim or Septra. People with weakened immune systems, including those living with HIV or undergoing chemotherapy, face a higher risk of severe or prolonged illness and should seek care promptly if symptoms develop.
The CDC recommends that anyone experiencing persistent watery diarrhea lasting several days, especially with fatigue or significant weight loss, contact a health care provider and mention recent consumption of fresh herbs, leafy greens or berries. Diagnosis requires a specific stool test, since the parasite is not detected by standard bacterial cultures.
Prevention Guidance
Because Cyclospora oocysts are resistant to routine chlorine treatment used in water systems, thorough washing of produce does not guarantee removal of the parasite once it is present on food. Health officials instead point to source-level controls, including agricultural water testing and worker hygiene standards on farms, as the primary defense against contamination.
The CDC advises consumers to:
- Stay informed about active recalls tied to Cyclospora, particularly involving herbs, leafy greens and berries
- Wash produce under running water, even though this will not eliminate all risk
- Seek medical attention for diarrhea lasting more than a few days
- Avoid preparing food for others while symptomatic
An Annual Pattern
Cyclosporiasis outbreaks have become a recurring feature of U.S. summers over the past decade, with the CDC and FDA logging thousands of cases in prior years tied to specific produce items once traceback investigations concluded. The scale of this year’s case count, now exceeding 11,500 across more than four-fifths of the country, places it among the larger seasonal totals the agency has recorded.
The CDC says it will continue to update its case figures as more states report data and as the multistate investigation into the source of the outbreak progresses. Officials have not announced any product recalls specifically tied to the current case total as of this week’s update.
