Cyclosporiasis cases rise as fresh produce comes under scrutiny

Allegheny County reported 11 cases of cyclosporiasis on July 14 and said it was working with state and federal partners to investigate, as fresh produce came under scrutiny in a widening parasite outbreak. Pennsylvania had recorded 28 cyclosporiasis cases so far in 2026, including 11 in the Pittsburgh region.

Cyclosporiasis is an intestinal infection caused by the Cyclospora parasite. It can trigger watery diarrhea, fatigue, stomach cramps, nausea and loss of appetite, and symptoms can last for weeks. The illness usually starts about a week after exposure, though the incubation window can range from 1 to 20 days, which makes it harder for patients to connect symptoms to a meal days earlier.

That delay is one reason washing produce is not always enough. The CDC says fruits, vegetables and herbs should be thoroughly washed under running water before eating, cutting or cooking, but the parasite can survive on raw produce that is eaten without heat. Cooking or high heat kills Cyclospora, which is why raw items have drawn attention in the current investigation. Lettuce and salad greens have been flagged as a possible source, while raspberries have been tied to previous outbreaks.

The federal response has stretched far beyond Pennsylvania. The CDC said domestically acquired cases were being reported in multiple states in July, with at least 31 states involved by mid-month. Later reporting pushed that total to 34 states, and Michigan had the highest number of illnesses. The spread has underscored how quickly a foodborne parasite can move through interstate produce chains before investigators identify a common ingredient.

Lee H. Harrison, M.D., a University of Pittsburgh professor in the Infectious Disease Division and director of the Center for Genomic Epidemiology, has helped explain the illness as health officials track the cases. The outbreak has put the practical weakness in focus: fresh produce is often eaten raw, symptoms can take days to appear, and a common source can remain unknown while case counts rise.

For patients, the clearest warning is persistent gastrointestinal illness. Watery diarrhea and fatigue that linger for days, or sudden stomach symptoms after eating raw produce, warrant medical attention while investigators continue to trace the source.