Health authorities are scrambling to trace the source of a surge in cyclosporiasis, a parasitic illness that has sickened hundreds of Americans in recent weeks. The Centers for Disease Control and Prevention confirmed 145 cases between May and mid-June, but state-level data suggests the true toll is far higher.
Michigan alone has recorded more than 170 infections across seven counties in the past nine days, according to Dr. Natasha Bagdasarian, the state’s chief medical executive. That figure already dwarfs the state’s usual annual tally of about 50 cases. “We expect more cases to be reported,” Bagdasarian said, noting the outbreak is spreading faster than typical seasonal patterns.
Cyclosporiasis cases typically spike between May and August, linked to contaminated fresh produce like imported berries, herbs, and salad greens. But the current wave has alarmed public health officials because of its intensity and geographic spread. The CDC is working with state partners to identify the contaminated food items driving the outbreak, though no specific source has been pinpointed yet.
The illness is caused by the microscopic parasite Cyclospora cayetanensis. Symptoms usually appear about a week after ingestion and include watery diarrhea—often described as “explosive”—along with stomach cramps, nausea, fatigue, and low-grade fever. Infections can last weeks if untreated and may relapse, especially in people with weakened immune systems.
Health experts urge anyone experiencing persistent diarrhea to seek medical testing, as cyclosporiasis requires specific antibiotics—common anti-diarrheal medications won’t work. The CDC recommends that clinicians consider cyclosporiasis in patients with prolonged diarrheal illness, particularly those with recent travel or exposure to imported produce.
The outbreak adds to a broader pattern of foodborne illness challenges facing regulators. As the U.S. grapples with emerging zoonotic threats like screwworm in Texas, the cyclosporiasis surge underscores vulnerabilities in the food supply chain. Meanwhile, budget pressures at the CDC and FDA have raised questions about whether surveillance systems can keep pace with seasonal outbreaks.
For now, officials advise consumers to wash all fresh produce thoroughly, though that may not fully eliminate Cyclospora because the parasite can cling to surfaces. Cooking kills the organism, so heat-treated foods pose less risk. The CDC continues to update its case count weekly, and state health departments are ramping up testing and interviewing patients to trace common food exposures.
As the investigation unfolds, the episode highlights the persistent threat of imported produce contamination—a problem that has prompted calls for stronger food safety inspections at ports of entry. The current outbreak, while not yet linked to a single source, fits a pattern of summer cyclosporiasis spikes that have baffled regulators for years.
