Aug. 14, 2026, 3:50 p.m. ET

An outbreak of cyclosporiasis, a parasitic infection known for causing explosive diarrhea that has been linked to recalled iceberg lettuce, has expanded to two additional states since early August, according to the Centers for Disease Control and Prevention (CDC).

An unprecedented wave of infections has hit the United States since May, resulting in thousands of illnesses and two deaths. The CDC, which lags significantly behind states in reporting infections, pinpointed 13,895 laboratory-confirmed cases across 47 states between May 1 and its latest update on Aug. 10. At least 10,455 additional cases have not yet been confirmed by laboratories, the CDC said.

Is lettuce safe to eat now? What to know amid cyclospora outbreak

Ohio and Michigan have led the charge in reporting cyclosporiasis incidents, with Michigan's health department stating on Aug. 13 that it had 13,909 cases, including the first two deaths identified in the nationwide outbreak.

Cyclosporiasis, an illness caused by the parasite Cyclospora cayetanensis, results in unpleasant gastrointestinal symptoms, often associated with food poisoning, such as diarrhea, nausea and vomiting. It is usually contracted through contaminated food or water, and it is not generally known to be deadly; however, it can cause more serious complications in people with compromised immune systems or other underlying health issues.

Multiple outbreaks, only one tied to lettuce

Not all of these clusters have been linked to the same source, however. The largest outbreak was traced by the Food and Drug Administration back to recalled iceberg lettuce grown by produce giant Taylor Farms in central Mexico.

The Taylor Farms-related outbreak was previously identified as reaching 15 states: Illinois, Indiana, Kansas, Kentucky, Michigan, Ohio, Oklahoma, Pennsylvania, West Virginia, Missouri, Arkansas, Iowa, Nebraska, New Hampshire and North Carolina.

It has since expanded to include Maine and Massachusetts, according to the CDC. At least 9,481 cases were confirmed as being part of the lettuce-related outbreak, up from 6,358 on Aug. 5.

Additional information about where the lettuce was sold has also emerged, thanks to FDA enforcement reports - and it wasn't mostly Taco Bell. The popular fast food chain made headlines as the first to be named in the investigation.

Outbreak linked to lettuce expands to more states. See map

The states identified as being specifically affected by illnesses traced back to lettuce were identified after health officials interviewed and tested sick people to determine whether their infections were related. Those that are related are considered part of the same outbreak, likely stemming from the same source. Thus far, these states are the only ones the CDC has been able to confirm as related to one another and trace back to the lettuce.

Most recalled Taylor Farms lettuce was sent to Walmart, other retailers

While Taco Bell was the first chain to make headlines in the FDA's investigation, it actually received only a very small portion of recalled lettuce, according to an FDA enforcement report.

Yum! Brands, the parent company of Taco Bell, KFC and Pizza Hut, received only 5,900 of the 236,192 total recalled lettuce cases - a little less than 2.5%

The largest recipient by far was Walmart, specifically under its in-house brand Marketside, which received 109,476 cases (about 46%) of whole and shredded iceberg lettuce. Taylor Farms itself received the second-largest amount, with 68,897 cases or about 29%.

Other recipients included fast-food chains Subway and Jack in the Box, distributor Cross Valley Farms and food service providers Sysco, Markon and Peak.

In addition to the Michigan-centered outbreak, officials are investigating multiple separate clusters of the gastrointestinal illness, including one that has sickened at least 172 people. The FDA has not yet identified the source of additional outbreaks.

The source of a cyclosporiasis cluster is more difficult to track than foodborne illnesses due to a long incubation period, difficulty obtaining samples and the inability to use the same genetic tracking tools available for pathogens like E. coli and listeria, as previously reported by USA TODAY.