The US Centers for Disease Control and Prevention (CDC) is investigating a surge in cyclosporiasis cases caused by the cyclospora parasite, which has infected over 400 people across 18 states. The illness, characterized by watery and sometimes explosive diarrhea, has led to at least 20 hospitalizations.
Outbreak Details and Affected States
Between 1 May and 16 June, the CDC recorded 145 cases across 17 states. New York, Texas, Illinois, and Michigan have been hardest hit. Other affected states include Alaska, Colorado, Connecticut, Florida, Georgia, Louisiana, Massachusetts, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, and Wisconsin. No deaths have been reported.
Outside the CDC's initial reporting period, Michigan has seen a large and growing outbreak, with over 300 cases since 22 June. The state typically identifies only about 50 cases annually, according to its health department. New York has reported 107 cases since 1 May, with New York City cases roughly doubling from January through June compared to the same period in 2025, as reported by the New York Times.
Parasite Transmission and Symptoms
Cyclospora spreads through raw produce and water contaminated with human feces. Symptoms include watery diarrhea, cramps, nausea, fatigue, loss of appetite, low-grade fever, and vomiting. The most commonly reported symptom is watery diarrhea with frequent and sometimes explosive bowel movements, according to the CDC. Symptoms typically appear two days to two weeks after ingestion, and not everyone experiences symptoms.
Investigation and Response
The CDC is working with the US Food and Drug Administration (FDA) and local officials to investigate clusters in several states. Infected individuals had not traveled abroad in the two weeks before illness, suggesting domestic sources. There is no immediate evidence of a single multi-state outbreak linking all cases, so investigators are probing various potential clusters and sources.
The illness is seasonal in the US, with peaks between May and August when consumption of fresh produce like basil, cilantro, spinach, and berries increases—items linked to past outbreaks. The CDC notes the current case count is alarmingly high with sources yet unidentified.
Treatment and Prevention
Most people with healthy immune systems recover without treatment in days or weeks. Severe cases are treated with antibiotics. The CDC advises thorough washing of fresh produce, hands, and kitchen surfaces. Those with symptoms should see a healthcare provider and report positive tests to their local health department. Staying hydrated is crucial to prevent dehydration. Cyclosporiasis is not typically transmitted person-to-person.
