CDC Investigates Rise in Cyclospora Cases as U.S. Reports 843 Infections

California has reported cases of cyclosporiasis as federal health officials investigate a nationwide increase in infections caused by the parasite Cyclospora cayetanensis, which can cause prolonged watery diarrhea and other gastrointestinal symptoms, Aidin Vaziri reported for the San Francisco Chronicle.

Health officials are investigating a nationwide increase in Cyclospora infections.

The U.S. Centers for Disease Control and Prevention (CDC) said Friday that 843 confirmed domestically acquired cases had been reported across 31 states since May 1.

As of July 9, no deaths had been reported, although 86 patients had been hospitalized.

The CDC said the number of cases is expected to increase as investigators review more than 1,500 additional reports to determine whether infections were acquired within the United States or during international travel.

According to the California Department of Public Health, the state recorded 41 provisional cases between January and June, down from 80 cases during the same period in 2025.

Most California cases were linked to recent international travel. Since May 1, the state has identified four domestically acquired infections, including two involving individuals who had recently traveled to the U.S. Midwest. Those investigations remain ongoing.

The CDC has not yet released state-by-state case totals. Its national figures include only confirmed infections among people who consumed food in the United States and did not report international travel during the 14 days before becoming ill.