Cyclospora Outbreak Tied to Lettuce Tops 10,900 Cases Across 17 States

A parasitic outbreak that began quietly in June has turned into one of the largest cyclosporiasis events the United States has recorded, with federal investigators still unable to name a single definitive food source for the bulk of the cases even as the case count keeps climbing.

According to the CDC's outbreak investigation page, the total case count has reached 10,930 illnesses reported from 17 states, with illness onset dates running from June 14 through August 11. At least 454 hospitalizations have been reported overall, and two deaths were recorded in Michigan.

The numbers look even larger at the state level. Michigan's Department of Health and Human Services reported 14,277 total cases as of August 20, with 335 people indicating they'd been hospitalized. Two deaths have been confirmed as part of Michigan's outbreak alone.

Investigators have identified one major cluster at the center of this: a group of roughly 1,644 cases spanning Indiana, Kentucky, Michigan, Ohio, and West Virginia that the CDC and FDA tied, in mid-July, to shredded iceberg lettuce from Taylor Farms de Mexico served at Taco Bell locations in those five states. A voluntary recall of the product followed on July 17. The broader national surge, however, involves cases reported from across 17 states whose source has not been confirmed.

Michigan's health department noted that lettuce or salad greens may be a potential source for its cases, but added that other food items can't be ruled out, and no specific grower or supplier has been identified.

One wrinkle in the investigation came when the FDA retracted a single lettuce laboratory test as a false positive and issued an apology to Taylor Farms for the error. But as TeleDirectMD's physician-reviewed outbreak guide noted, the CDC and FDA said that development does not change the overall investigation, which rests on epidemiologic and traceback data, and the recall remains active.

Cyclosporiasis is caused by Cyclospora cayetanensis, a microscopic parasite. It spreads through contaminated fresh produce or water and does not transmit person to person. Symptoms include watery diarrhea, abdominal cramps, nausea, and fatigue, with an incubation period of roughly 7 to 10 days after exposure.

Because the illness can look like any number of summer GI bugs, clinicians are being urged to think carefully before sending patients home with reassurance. Diagnosis requires stool microscopy to identify Cyclospora oocysts, a test that labs don't run automatically. According to a CDC Health Alert Network notice reviewed for this article, the agency is asking all providers to report confirmed cases promptly to local health departments and to conduct detailed food and travel histories with affected patients.

The CDC also flagged something that matters when interpreting these numbers: cyclosporiasis is often underdiagnosed and underreported, so the true count is likely higher than what has been captured. This time last year, the agency had received 249 confirmed domestic cases over the same period, making the scale of the 2026 surge clearer.

The summer cyclosporiasis season, which the CDC marks as running through August 31, is nearly over. But with new cases still being added and a source for the majority of illnesses still unconfirmed, this outbreak is not closed.

Sources cited:
- CDC Cyclosporiasis Outbreak Investigation Update (https://www.cdc.gov/cyclosporiasis/outbreaks/07-26/investigation.html)
- CDC Health Alert Network Notice, HAN 00531 (https://www.cdc.gov/han/php/notices/han00531.html)
- Michigan DHHS Infectious Disease Outbreaks (https://www.michigan.gov/mdhhs/keep-mi-healthy/infectious-diseases/infectious-disease-outbreaks)
- TeleDirectMD Cyclosporiasis Outbreak 2026 Guide (https://teledirectmd.com/health-guides/cyclosporiasis-outbreak-2026-guide/)
- Infection Control Today, Cyclosporiasis Outbreak 2026 (https://www.infectioncontroltoday.com/view/cyclosporiasis-outbreak-2026-1-645-confirmed-cases-34-states-with-growing-cluster-michigan-ohio-west-virginia-kentucky)