Federal health officials are investigating a multistate outbreak of cyclosporiasis, a parasitic intestinal illness that can cause severe, sometimes “explosive,” diarrhea, with Pennsylvania reporting 28 cases so far this year.
The Centers for Disease Control and Prevention (CDC) confirmed Tuesday that a common source appears to be linked to hundreds of illnesses across at least four Midwestern states: Michigan, Ohio, West Virginia and Kentucky. Investigators have not yet identified the exact source, although lettuce and other salad greens remain among the produce items being examined.
Pennsylvania health officials say the state’s case count remains relatively low compared with neighboring outbreak areas. Of the 28 reported cases, 14 have occurred in southeastern Pennsylvania. By comparison, the state recorded 40 cases during all of 2025 and 87 cases in 2024.
Cyclosporiasis is caused by the microscopic parasite *Cyclospora cayetanensis*, which spreads through food or water contaminated with human waste. In the United States, previous outbreaks have often been linked to imported fresh produce, including leafy greens, basil, cilantro, and berries.
The CDC said tracing the source is especially challenging because symptoms can take anywhere from two days to two weeks to appear, and the parasite cannot yet be analyzed using the rapid whole-genome sequencing techniques commonly used in other foodborne outbreak investigations. As a result, identifying a specific food source may take weeks or may never be possible.
Symptoms include severe watery diarrhea, loss of appetite, nausea, vomiting, stomach cramps, bloating, low-grade fever, and extreme fatigue. Some people recover on their own within a few days, but others may remain ill for weeks if left untreated. Diagnosis requires a specialized stool test because routine laboratory examinations may not detect the parasite.
Health officials recommend thoroughly washing fresh fruits and vegetables, practicing good hand hygiene, and seeking medical care if diarrhea persists for more than a week, especially during the current outbreak.
Source: CDC, The Hill, Phila Inquirer, WHYY