A stomach-churning parasite is spreading across the United States at a pace health officials call extraordinary. Cyclosporiasis — an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis — has now been confirmed in 34 states, with federal investigators zeroing in on lettuce and salad greens as the possible source.
A Six-Fold Surge in Cases
As of July 13, the Centers for Disease Control and Prevention had confirmed 1,645 domestically acquired cases, according to a detailed breakdown from Infection Control Today — a six-fold increase over the 249 cases recorded by the same date last year. Another 5,100 suspected cases are still pending verification, and a fast-growing cluster of more than 400 cases spans Michigan, Ohio, West Virginia, and Kentucky.
Patients have ranged in age from 2 to 95, with a median age of 44, and about 56% of cases have been in women. So far, 141 people — roughly 9% of confirmed cases — have been hospitalized. No deaths have been reported.
Even those numbers likely understate the outbreak. “Because cyclosporiasis is often underdiagnosed and underreported, the true number of illnesses is likely higher than what has been reported,” the CDC said, per Infection Control Today. The CDC’s outbreak page notes the illnesses trace back to May 1, with the newest multistate cluster involving people who fell ill on or after June 22.
Is Your Salad Safe?
Investigators have not yet pinned down a definitive culprit. Lettuce and salad greens are under active investigation, but the CDC has been careful to note that “a specific food item has not yet been confirmed as the source,” according to Infection Control Today. Historically, cyclosporiasis outbreaks in the U.S. have been tied to fresh produce — items like basil, cilantro, bagged salad mixes, and raspberries — because the parasite travels on food contaminated before it ever reaches the grocery store.
That is what makes this outbreak particularly frustrating for consumers: unlike bacteria, Cyclospora is not reliably removed by routine rinsing, and cooking is the only sure way to kill it — cold comfort for anyone whose lunch is a salad.
Symptoms: Unpleasant, Persistent, and Easy to Misdiagnose
Cyclosporiasis announces itself with watery diarrhea that can be frequent and, in some cases, explosive — along with appetite loss, weight loss, bloating, nausea, and deep fatigue. Symptoms typically begin about a week after exposure, with an incubation window of 2 to 14 days, per Infection Control Today.
Left untreated, the illness can drag on for days or even longer than a month, often in a miserable remitting-and-relapsing pattern where patients think they have recovered only to be knocked down again. Adding to the challenge, the parasite is routinely missed by standard laboratory stool panels. The CDC recommends clinicians specifically order Cyclospora testing, ideally PCR-based molecular tests, when patients present with prolonged watery diarrhea.
The good news: cyclosporiasis is treatable. A 7-to-10-day course of trimethoprim-sulfamethoxazole — a common antibiotic combination — clears the infection in most otherwise healthy patients, with longer courses for those with weakened immune systems, according to Infection Control Today.
How to Protect Yourself
Until investigators identify the source, health experts suggest common-sense precautions. Wash hands with soap and water for a vigorous 15 to 20 seconds — notably, soap and water beats alcohol-based sanitizer against this parasite when hands are visibly soiled, per CDC guidance cited by Infection Control Today. Scrub cutting boards and counters with detergent before disinfecting, since standard disinfectants alone are ineffective against Cyclospora. People at higher risk — the elderly, young children, and the immunocompromised — may reasonably choose cooked vegetables over raw salads while the investigation continues.
Most importantly, anyone who has had watery diarrhea lasting more than a few days should see a doctor and mention this outbreak by name. Because the illness mimics more common stomach bugs and evades routine testing, patients who advocate for specific Cyclospora testing get diagnosed — and treated — faster.
What Happens Next
The CDC and state health departments are continuing traceback work to identify the contaminated product and where it entered the food supply. With more than 5,000 suspected cases still being verified, the official count is almost certain to climb in the coming weeks. Until then, this outbreak is a reminder that in a national food system, a single contaminated crop can reach dinner tables in 34 states before anyone knows it is there.
