By The Chronicle Staff

Federal health officials are investigating a nationwide increase in cyclosporiasis cases, including a multi-state outbreak linked to recalled iceberg lettuce that has affected Ohio and four neighboring states.

The Centers for Disease Control and Prevention reported July 21 that 4,173 laboratory-confirmed domestic cases of cyclosporiasis have been reported since May 1, with 308 hospitalizations and no deaths.

The CDC also says it is aware of more than 7,400 additional cases reported by state and local health departments that still require laboratory confirmation and further review, with many of those additional reports coming from Ohio and Michigan.

As of July 16, the Ohio Department of Health reported 1,316 cases in the state and 96 hospitalizations, according to the Ohio Capital Journal.

Officials cautioned that the true number of illnesses is likely higher than reported because some people recover without medical care and are never tested.

Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora. People usually become infected after eating food or drinking water contaminated with the parasite. Symptoms often include watery diarrhea, fatigue, loss of appetite, stomach cramps, bloating, nausea and weight loss.

Symptoms typically begin about a week after exposure, though they can start anywhere from two days to two weeks or longer.

The CDC, the U.S. Food and Drug Administration and public health officials in several states are investigating the five-state outbreak linked to iceberg lettuce. Health officials have warned consumers not to eat recalled iceberg lettuce from Taylor Farms de Mexico that may have been sold in stores or served in restaurants.

On July 17, Taylor Farms de Mexico recalled all iceberg lettuce sourced from central Mexico. The recall includes iceberg lettuce sold at retail stores, served in restaurants and distributed to food-service customers. The FDA reported that recalled products were distributed to multiple states, including OhioConsumers who purchased recalled lettuce should throw it away or return it to the store. Restaurants and retailers that received recalled iceberg lettuce should discard it and should not serve or sell it. The CDC also recommends washing items and surfaces that may have touched the recalled lettuce with hot, soapy water or in a dishwasher.

In an earlier update, federal officials said shredded iceberg lettuce served at some Taco Bell locations in Indiana, Kentucky, Michigan, Ohio and West Virginia was linked to the outbreak. The investigation has since expanded to include recalled iceberg lettuce sold through retail and restaurant channels.

People who are sick with symptoms consistent with cyclosporiasis should contact a health care provider, especially if diarrhea is severe or lasts more than a few days. Patients may need to specifically request testing for Cyclospora, because routine stool tests do not always screen for the parasite.

Health care providers are advised to report cases to their local health department according to local reporting practices. State and local health officials may contact people who are sick to ask what they ate in the two weeks before symptoms began, information that can help investigators identify contaminated foods and prevent additional illnesses.

The CDC said cyclosporiasis cases typically increase during the spring and summer. The agency is publishing weekly surveillance updates this year because multiple states are seeing higher case counts than during the same period in 2025.

For local residents, the guidance is straightforward: check refrigerators for recalled iceberg lettuce, do not eat lettuce covered by the recall, and ask restaurants about the source of iceberg lettuce if it is unclear. Anyone with symptoms should stay hydrated and seek medical advice.

The outbreak investigation remains open, and federal officials say case counts may continue to rise as additional reports are confirmed. ■