Cyclospora outbreak spreads across more than half of U.S. states

Federal health officials had counted 843 confirmed domestic cyclosporiasis cases since May 1 and were reviewing more than 1,500 additional suspected illnesses as the summer outbreak widened across the country. The Centers for Disease Control and Prevention said the 2026 season began on May 1 and runs through August 31, the period when the parasite most often surges.

Cyclosporiasis is caused by Cyclospora cayetanensis, a microscopic parasite that spreads when people ingest food or water contaminated with feces. In the United States, investigators have often linked outbreaks to fresh produce, and the CDC has identified raspberries, basil, snow peas, mesclun lettuce, cilantro, melons and cucumbers in past foodborne outbreaks. That makes farms, packing lines, distributors and retail handling points central to the investigation.

The disease is a nationally notifiable condition and is reportable in 43 states, the District of Columbia and New York City, giving public health departments a broad network for tracking cases as they emerge. The CDC said states are likely reporting higher counts than those reflected in its national data while officials work to confirm whether the additional illnesses were domestically acquired cyclosporiasis.

People can be infected more than once, and those in poor health or who are immunocompromised face higher risk for severe or long illness. Because outbreaks have been identified nearly every year since the mid-1990s and most U.S. cases are reported in spring and summer, the current rise fits a pattern health officials know well, even as they race to pin down the food source.

The CDC typically coordinates 17 to 36 multistate foodborne illness investigations each week, placing the cyclosporiasis response inside a constant federal monitoring system. With cases already reported in California and more suspected illnesses under review, the outbreak is now a test of how quickly state and federal investigators can trace a parasite that often hides in fresh produce long before it reaches a shopper’s kitchen.