Cyclospora Outbreaks Expand Across the United States with Unidentified Sources

The Centers for Disease Control and Prevention (CDC) reports that nearly 14,000 domestically acquired cases of cyclosporiasis have been confirmed in the United States since May of this year, far exceeding the roughly 1,180 cases recorded over the same period last year. The Food and Drug Administration (FDA) indicates that at least 9,480 of those cases are linked to an outbreak traced to iceberg lettuce and have been reported in 17 states; Maine and Massachusetts were added to that list most recently. A Nexstar analysis of health data across multiple states estimates that more than 30,000 cases—both confirmed and probable—have occurred nationwide this year, encompassing domestic and international acquisitions and some unconfirmed laboratory tests.

The Hill

The FDA’s tracking shows seven active investigations into cyclospora outbreaks, while three investigations—affecting 18, eight, and two people respectively—have been closed. Only the iceberg-lettuce outbreak has an identified source; the remaining investigations lack confirmed origins. Two separate outbreaks have grown in size: one first reported in early August now involves 11 cases, and another first noted in late July has risen to 172 cases from an earlier 115. The FDA continues traceback efforts for these and three additional active outbreaks.

The Hill

Two patients in Michigan died after falling ill before the lettuce recall, though state health officials noted that both individuals had significant underlying health conditions. Healthcare experts advise anyone experiencing prolonged diarrhea—typically lasting more than one to two weeks—to seek medical care, as untreated cyclosporiasis can persist for a month or longer. The Cleveland Clinic outlines treatment options that may include antibiotics, antidiarrheal medications, and hydration.

The Hill

Gwen Biggerstaff, deputy director of the CDC’s Division of Foodborne, Waterborne, and Environmental Diseases, explains that the long incubation period of cyclospora and challenges in sequencing the parasite can cause investigations to take a significant amount of time, contributing to uncertainty about the true source of many outbreaks. She also suggests that the actual number of infections this summer is likely higher than official tallies, given that not all infected individuals develop symptoms, require hospitalization, or undergo confirmatory testing.

The Hill

Given the expanding case counts, the presence of multiple active investigations without identified sources, and the potential for underreporting, public-health authorities emphasize the need for continued surveillance, rapid diagnostic testing, and public awareness of symptoms. The situation underscores the difficulty of controlling food-borne parasites when source tracing is hampered by delayed symptom onset and limited laboratory capacity.

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