United States health authorities are investigating a significant outbreak of cyclospora infections that have surged across the country in 2026. Since May 1, the Centers for Disease Control and Prevention (CDC) has confirmed 1,645 domestically acquired cases and is reviewing over 5,100 additional reports to determine their connection to the outbreak. The CDC anticipates that infection numbers will continue to rise through August.

Cyclospora infections have been reported in more than 30 US states this year, with the highest concentration of cases in the Midwest and Northeast regions. Michigan has reported the largest number of infections, ranging between 501 and 900 cases. Other states with reported cases include Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Iowa, Kansas, Louisiana, Maryland, Massachusetts, Minnesota, Nebraska, New Hampshire, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Utah, Virginia, Washington, West Virginia, and Wisconsin, though many have fewer than 30 infections.

Michigan’s health department chief medical executive, Natasha Bagdasarian, noted that the state’s aggressive investigation and reporting efforts may partly explain why Michigan appears to be the hardest hit.

Symptoms of cyclospora infection typically emerge about a week after consuming contaminated food or water, but can appear as early as two days or as late as two weeks post-exposure. While rarely life-threatening, the illness can cause prolonged gastrointestinal symptoms and is generally treated with antibiotics.

The Food and Drug Administration (FDA) is actively interviewing infected individuals to trace back the foods consumed before illness onset, following supply chains back to farms to identify contamination sources.

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