CDC investigates Cyclospora parasite behind diarrhea cases in 18 states

The CDC has received 145 reports of U.S.-acquired cyclosporiasis, a Cyclospora infection that can cause severe diarrhea, with illnesses spread across 17 states and state-level reporting pushing the tally to 18. The parasite moves through contaminated food or water, especially fresh fruits and vegetables, and Michigan health officials told residents with sudden, ongoing diarrhea to contact a health-care provider.

Cyclospora is a microscopic parasite that causes an intestinal illness the CDC tracks as a nationally notifiable disease, with reports required in 47 states, the District of Columbia and New York City. The agency’s surveillance page, updated July 1, said there was no evidence of a single multistate outbreak tying all of the cases together. Instead, investigators are treating the reports as several clusters, which is common in a food-safety system that must sort through scattered illnesses before the source is clear.

The illness pattern shows why Cyclospora is watched closely in late spring and summer. CDC considers cyclosporiasis season to run from May 1 through August 31, and the latest cases fell squarely in that window. Patients ranged from 5 to 86 years old, with a median age of 42 and a median illness-onset date of May 13. Of the 145 people with available information, 20 were hospitalized and no deaths were reported.

Federal investigators are also working through a separate active inquiry on the FDA’s outbreak page, which listed a Cyclospora investigation posted June 17 with the product source still not identified. The lack of a clear culprit underscores how hard multistate foodborne outbreaks are to trace quickly, especially when the same pathogen can appear in multiple clusters rather than one obvious event. The CDC says it typically coordinates 17 to 36 multistate foodborne-illness investigations each week, and most of those are caused by Campylobacter, E. coli, Listeria or Salmonella.

Public-health guidance remains straightforward: wash hands with soap and water before and after handling raw fruits and vegetables, and wash produce thoroughly under running water before eating, cutting or cooking it. In Michigan, officials urged people with ongoing diarrhea to seek medical care and alert their local health department if other family members are showing the same symptoms.