The 2026 US cyclosporiasis season closed with 18,445 laboratory-confirmed cases across 49 states and the District of Columbia, according to the Centers for Disease Control and Prevention.
The season ran from May 1 through August 31 and left 990 people hospitalized and 2 dead.
For scale, the same four-month window in 2025 produced only 1,180 cases nationwide. This year's tally is more than 15 times that number.
Much of the surge traced back to a single supplier. In the CDC's ongoing multistate outbreak investigation, epidemiologic and traceback data pointed to iceberg lettuce from Taylor Farms de Mexico as the source.
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That specific outbreak accounts for 11,458 illnesses across 20 states, with 495 hospitalizations and both deaths, which occurred in Michigan in people with underlying health conditions.
Earlier in the summer, the two Michigan deaths were first reported when the case count was still a fraction of today's total.
What cyclospora does to the body
Cyclosporiasis is caused by a microscopic parasite called Cyclospora cayetanensis, which infects the small intestine after a person eats contaminated food or drinks contaminated water.
The CDC describes the hallmark symptom as watery diarrhea that can come and go.
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Other common symptoms include stomach cramps, loss of appetite, nausea, fatigue and low-grade fever.
Illness typically begins about a week after exposure, though the incubation window can range from 2 days to more than 2 weeks.
Without treatment the infection can last from a few days to more than a month, and symptoms may recur.
A fuller rundown of what the parasite does to the body was published as the outbreak was still growing.
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The parasite does not spread directly from person to person.
It has to spend at least 1 to 2 weeks outside the body to become infectious, which is why food and water are the usual routes.
Treatment is a common antibiotic
Cyclosporiasis is treated with trimethoprim-sulfamethoxazole, an antibiotic combination sold under the brand names Bactrim, Septra and Cotrim.
People with a sulfa allergy should ask their doctor about alternatives. Rest and fluids help with recovery.
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Anyone with persistent watery diarrhea, especially if it has lasted more than a few days or is accompanied by dehydration, should contact a healthcare provider and mention any recent lettuce or fresh produce exposures so testing can be ordered.
The recalled lettuce should already be gone
Taylor Farms de Mexico recalled all iceberg lettuce sourced from central Mexico on July 17, 2026.
The Food and Drug Administration says the best-by dates on the recalled product have passed and it should no longer be available in stores or restaurants.
The company shipped the affected lettuce to 31 states.
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The last recorded illness onset date in the outbreak was August 15, so the season now appears to be winding down.
The CDC continues to update its outbreak page as delayed reports arrive, and has flagged that the overall count will keep drifting upward, it can take roughly six weeks from symptom onset to when a confirmed case reaches federal tallies.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.