CDC races to trace parasite behind multistate illness outbreak
Michigan emerges as the hardest-hit state as investigators hunt for the contaminated food source.
MICHIGAN CITY, INDIANA — A summer meal that seemed perfectly safe has become the focus of an urgent public health investigation as the Centers for Disease Control and Prevention races to identify the source of a parasite outbreak spreading across multiple states. With hundreds of illnesses reported and, no contaminated food yet identified, health officials are working against time to stop the outbreak before it grows even larger.
The illness is caused by Cyclospora cayetanensis, a microscopic parasite that infects the intestines after people consume contaminated food or water. The CDC has confirmed 145 domestically acquired cases across 17 states, resulting in 20 hospitalizations. At the same time, Michigan is battling a separate outbreak that has sickened more than 300 people, making it the hardest-hit state this season and intensifying concerns about food safety nationwide.
“Our investigators are working to determine the exact source. We believe many cases are linked to a contaminated food item, but identifying it takes time because patients often become ill days or even weeks after eating it. We are interviewing patients and tracing food purchases to find any common link," said Dr. Natasha Bagdasarian, Chief Medical Executive and Chief Deputy for Health at the Michigan Department of Health and Human Services.”
Investigators from the CDC, the Michigan Department of Health and Human Services, and state agriculture officials are interviewing patients, tracing food purchases, and examining supply chains in hopes of identifying the contaminated product. So far, the source remains a mystery. In previous outbreaks, Cyclospora has been linked to fresh produce, including cilantro, basil, leafy greens, and berries, but officials have not connected the current illnesses to any single food item.
Michigan Department of Health has reported the largest Cyclospora outbreak this season in USA on July 5, 2026 at 3:08 PM. Photo: Jeff Kowalsky/Getty Images
The outbreak has spread beyond Michigan’s Monroe County into several neighboring counties, a dramatic increase for a state that typically records only about 50 cases of cyclosporiasis in an entire year. The unexpected surge has prompted health authorities to expand surveillance and encourage healthcare providers to test patients with persistent gastrointestinal symptoms.
Cyclospora infections often begin between two and 14 days after exposure. Symptoms include severe watery diarrhea, stomach cramps, nausea, fatigue, bloating, loss of appetite, and weight loss. While most people recover with appropriate treatment, the illness can linger for weeks and may return if left untreated.
As investigators continue searching for answers, public health officials are urging Americans not to ignore prolonged digestive illness, especially after eating fresh produce. Washing fruits and vegetables, practicing good hand hygiene, and seeking prompt medical care if symptoms develop can help reduce the risk of infection.
For now, the biggest challenge remains finding the contaminated source. Until that mystery is solved, every new case adds urgency to a race that could determine how quickly this outbreak is brought under control.