What is cyclosporiasis, the parasitic illness causing ‘explosive’ diarrhea?
State health officials in Michigan and Ohio are reporting thousands of cases of cyclosporiasis, a parasitic infection that causes “watery diarrhea,” loss of appetite, and weight loss.
The outbreak, which has exceeded 2,800 cases, occurs a year after the Trump administration cut funding to state and local health departments and reduced the scope of a program dedicated to coordinating information on foodborne illnesses, including cyclospora.
“It’s like putting a puzzle together,” said Barbara Kowalcyk, an associate professor at the George Washington University Milken Institute of Public Health and director of the university’s Institute for Food Safety and Nutrition Security. “You start taking pieces out of your puzzle – it’s harder to see the whole picture, and that’s what we’ve done. We’ve taken pieces out of the whole puzzle.”
In contrast, the Centers for Disease Control and Prevention (CDC) reported 843 confirmed cases and 1,500 suspected cases of cyclospora across 31 states as of Friday. Eighty-six people have been hospitalized, and no deaths have been reported. The CDC expects the federal case count to rise, partly due to delays typical in disease investigation.
Michigan appears to be especially affected, with health officials reporting a significant number of cases. Across the border, Ohio state officials are also reporting numerous cases. The health departments have not identified a specific source of the outbreak.
The Michigan health department is urging restaurants and commercial kitchens in the southeast region to thoroughly wash leafy greens, snow peas, certain herbs, and raspberries or, ideally, to cook them.
Cyclospora has a two-week incubation period, and the CDC assumes a six-week reporting lag between illness onset and receiving a case report. Investigating a disease with a long incubation period is challenging; to find potential links between cases, such as eating at the same restaurant or shopping at the same store, epidemiologists interview everyone with a lab-confirmed case. These interviews often occur two to four weeks after infection, making it difficult for individuals to recall what they ate.
Despite these challenges, Michigan’s chief medical executive Dr. Natasha Bagdasarian stated,
“there is clearly a linked outbreak happening right now.”
However, in an era of funding cuts, Kowalcyk noted that typical delays have likely been worsened.
“Have the funding cuts to public health impacted the current activities related to the cyclospora outbreak? I think they have,” said Kowalcyk. “If you’re understaffed you might be interviewing [patients] after 6-8 weeks,” she added.
Delays have been exacerbated in part by the Trump administration’s funding cuts, Kowalcyk explained, citing both grant reductions to state and local health departments and changes to federal surveillance systems that make it more difficult to obtain “the whole picture.”
In March 2025, the Trump administration cut $1 billion in funding to state and local health departments. Although these grants were earmarked for pandemic activities, Kowalcyk said they also helped build local health department capacity. Michigan alone lost $5.5 million, according to Bridge Michigan, a local news outlet.
“In state and local health departments, you might have people who are funded by three to four different funding sources,” said Kowalcyk. “If you take one away, you have to have people go part-time or you have to reduce your staff. There’s not a lot of choice, which means your capacity to scale up during an outbreak is limited.”
In July 2025, the Trump administration also reduced the scope of a program called FoodNet, which actively monitored foodborne outbreaks. FoodNet’s remit was narrowed from eight foodborne pathogens, including cyclospora, to shiga toxin-producing E. coli and salmonella alone.
FoodNet helped coordinate information across states and developed the frequently cited statistic that 48 million people in the US are sickened by foodborne illnesses annually, with 128,000 hospitalized and 3,000 deaths.
“Despite what the current HHS administration believes, ignoring a problem doesn’t make it go away,” public health and veterinary consultant Gail Hansen told the University of Minnesota’s Center for Infectious Disease Research and Policy (Cidrap) in August 2025. “States do not have the ability to coordinate information and data across states, and this cut will bring us back to a time before FoodNet.”
The administration has broadly defended the change in FoodNet’s scope as a reduction of duplicative efforts and stated that foodborne pathogen investigations are not impacted by the change.
“Narrowing FoodNet’s reporting requirements is, in part, because the surveillance landscape has changed since the collaboration began in 1995,” said a Department of Health and Human Services (HHS) update in April. “Today, other surveillance systems monitor for infection with FoodNet pathogens.”
A reporter for reached out to HHS for comment but did not immediately receive a response.
