See county maps of states linked to cyclosporiasis outbreak

A cyclosporiasis outbreak has spread to nine states, the Centers for Disease Control and Prevention said July 24, as the intestinal illness that causes weeks of severe and "explosive" diarrhea continues to sicken thousands of Americans, with case counts still climbing.

The nine states linked to the outbreak are Illinois, Indiana, Kansas, Kentucky, Michigan, Ohio, Oklahoma, Pennsylvania and West Virginia.

Cases have been reported in 41 states, the CDC said. However, the federal data lags state data for weeks. The agency is still investigating the illnesses unrelated to the multistate outbreak. 

The CDC noted on July 24: "This outbreak may not be limited to the states with known illnesses, and the true number of sick people is likely much higher than the number reported. This is because many people recover without medical care and are not tested for Cyclospora."

USA TODAY has collected figures directly from several state health departments to show where reported cyclosporiasis cases are concentrated and which communities have been hardest hit.

Michigan

Michigan leads the nation in cyclosporiasis cases, with more than 9,200 cases as of July 27, and 160 hospitalizations reported as of July 23. Wayne County has the most cases, with over 1,000, followed by Washtenaw and Oakland counties, according to county-level data from the state Department of Health and Human Services.

When the population is taken into account, Shiawassee County is the hardest-hit county with about 592 cases per 100,000 residents. That’s nearly double the rate reported in Lenawee County, the next-highest at about 335 cases per 100,000 residents.

Ohio

Ohio is another state that reported a record number of cyclosporiasis cases, with over 2,500 cases confirmed, based on the latest data available through July 23.

Lucas County reported the state's highest number of cases with 435, followed by Wood County with 309 and Sandusky County with 186. Sandusky County has the state's highest infection rate at about 317 cases per 100,000 residents, followed by Fulton County and Wood County.

Kentucky

As of July 22, the state received 468 reports of cases of cyclosporiasis, and 177 cases have been confirmed.

"While cases of cyclosporiasis normally rise in the spring and summer months, Kentucky is one of many states experiencing a larger-than-typical increase," said Beth Fisher, spokesperson at Kentucky Cabinet for Health and Family Services.

Fisher said Kentucky typically only has about 35 cases of cyclosporiasis each year.

Jefferson County, home to Louisville, has the state’s most cases, at 37, and Washington County has the state’s highest case rate at about 32 cases per 100,000 residents.

West Virginia

In West Virginia, cases are concentrated in the state's northern panhandle. The state reported 226 cases as of July 24, with Hancock County leading at a rate of 83 cases per 100,000 residents.

Indiana

Indiana has reported more than 800 cases as of July 27. Allen County saw the most cases, 144, followed by Marion County and Elkhart County. Steuben County has the state's highest infection rate at about 129 cases per 100,000 residents, followed by DeKalb County and Harrison County.

Kansas

As of July 22, Kansas reported 289 cases in total. Johnson County had the state's most cases, at 95, but Osage County had the state's highest infection rate at 45 cases per 100,000 residents.

Illinois

Illinois reported 513 cases with 39 hospitalizations as of July 23. Matthew Mata, the state’s health public information officer, said the county-level data is not available at the moment.

Oklahoma

Oklahoma had 172 cases as of July 20, and county-level data is not available. 

Pennsylvania

The state’s health department confirmed 45 cases in 2026 so far. The county-level data is not available. 

Connecticut

As of July 24, Connecticut confirmed 62 cyclosporiasis cases since May. Western Connecticut Planning Region had the most cases, with 33. That’s about five cases per 100,000 residents.

Florida

Florida reported 158 cases since May, based on the state’s Department of Health’s latest report as of July 18. With 33 cases, Miami-Dade County leads in the state, followed by Lee County and Broward County.

Arizona

Arizona has reported 19 cases this year. According to Magda Rodríguez, spokesperson with the Arizona Department of Health Services, none of those cases are associated with localized clusters or active outbreaks in Arizona.

Nevada

Nevada has reported two cases of cyclosporiasis since May 1, both in Clark County. Daniel Vezmar, a spokesperson for the Nevada Department of Health and Human Services, said the state has no evidence that the cases are linked to the nationwide outbreak.

This story was updated to reflect the latest available data for each state.