CDC investigates cyclosporiasis outbreak as cases top 1,500 nationwide

As of July 10, the CDC had received reports of 843 confirmed domestic cyclosporiasis cases since May 1 and was aware of more than 1,500 additional cases that still needed analysis to determine whether they were domestically acquired. The microscopic parasite Cyclospora cayetanensis is usually carried in contaminated food or water, which makes clusters difficult to trace when cases are scattered across farms, markets and states.

Multiple states had reported more cases in the past two weeks than during the same period in 2025. Michigan has been one of the hardest-hit states, and on July 5 state officials had not identified a specific produce grower, supplier or produce type as the source.

Public health investigators are focused on fresh produce because that is where Cyclospora outbreaks are most often linked. Infected people can shed the parasite in feces, allowing it to contaminate food, water and the environment when hygiene breaks down. People can also pick up cyclosporiasis while traveling outside the United States if they consume contaminated food or water. Produce tied to past outbreaks has included raspberries, basil, cilantro and salad mixes, along with sugar snap peas, lettuce, blueberries, blackberries, carrots, mangos, mint, scallions, mixed vegetable trays and fruit salads.

Symptoms usually show up about a week after exposure and can last for weeks if the illness is not treated. Watch for watery or explosive diarrhea, stomach cramps, nausea, bloating, fatigue, loss of appetite and weight loss. The illness can cause dehydration and, in some patients, require emergency medical care. Treatment is typically prescription antibiotics, and washing produce with water alone may not remove the parasite.

The outbreak has remained geographically broad, with at least 26 states affected and another tally at 31. Virginia is still seeing new cases, while Michigan health agencies continued interviews and traceback work with state, local and federal partners.