Michigan has been the epicenter of the cyclosporiasis outbreak, with state officials reporting about 13,900 cases. The state has also recorded the two deaths associated with the current outbreak, according to the CDC.
Other states that have reported significant numbers of infections include Ohio, New York, Missouri, Kansas, Indiana and North Carolina, although the rankings can change as states update their surveillance data.
Officials have cautioned that some of Michigan's recent increases reflect delays in laboratory reporting rather than a sudden surge in new infections.
The United States is experiencing its largest recorded surge of cyclosporiasis, with more than 15,000 laboratory-confirmed cases reported since May as health officials continue investigating a multistate outbreak linked to iceberg lettuce.
The CDC reported 15,716 laboratory-confirmed cases of cyclosporiasis acquired in the United States, along with another 11,841 cases considered possible and requiring further investigation, according to the latest update on Aug. 17. By comparison, only 1,180 cases were reported nationwide during the same period in 2025.
Federal officials have linked a major portion of the outbreak to iceberg lettuce sourced from central Mexico. The investigation by the U.S. Food and Drug Administration traced Taylor Farms of Mexico as a supplier, prompting the company to voluntarily remove affected iceberg lettuce from the U.S. market in July.
The investigation initially focused on infections among people who reported eating at Taco Bell. Epidemiological and traceback evidence subsequently expanded the investigation to a broader multistate outbreak involving lettuce distributed through multiple channels.
Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. The infection commonly causes watery diarrhea and can also lead to abdominal cramps, fatigue, nausea, and loss of appetite. Symptoms can persist for weeks or return after appearing to improve.
The parasite is generally transmitted when people consume food or water contaminated with Cyclospora. Fresh produce has been associated with previous outbreaks in the United States.
Health officials say people experiencing persistent diarrhea or other gastrointestinal symptoms should contact a health care provider about testing and treatment. Cyclosporiasis is treatable with antibiotics.
With the 2026 outbreak still evolving, federal and state health officials continue to investigate new cases and possible sources of exposure. The CDC says the true number of infections is likely higher than the confirmed total because cases can take time to identify and investigate.