Cyclosporiasis is a parasite that typically sickens about 50 Michigan residents each year between May 1 and Aug. 31. The cause has been linked to contaminated fresh produce. This year, an unprecedented number of people are ill from a widespread cyclosporiasis outbreak, and a source is not yet identified.
As of July 15, more than 3,700 cases have been reported in Michigan alone and that number continues to rise. The illness has spread to more than 30 states and more than 7,000 people, although the true extent of the outbreak is still under investigation. Current information indicates that lettuce and salad greens may be a potential carrier of the parasite, but no specific type of produce, grower or supplier has been identified.
Cyclosporiasis causes aggressive diarrhea, stomach cramps, nausea and fatigue. Symptoms can continue for weeks or even months if not treated. It is not usually spread from person to person. Patients who think they have a case of cyclosporiasis should seek medical care. They will be asked to provide a stool sample and a list of what they have eaten for the past two weeks.
Michigan State University experts are available to comment on many issues associated with the 2026 outbreak, including healthcare, wellness, and food and water safety.
Rebecca Schein is a board-certified pediatric infectious disease physician at MSU Health Care and assistant professor in the Department of Pediatrics and Human Development at the MSU College of Human Medicine.
Contact: scheinre@msu.edu
“Cyclosporiasis causes profuse watery diarrhea with stomach discomfort, bloating and a feeling of urgency to use the bathroom. If you have these symptoms for more than 48 hours, medical treatment is recommended. When you see the doctor, they will tell you how to provide a stool sample and, if you test positive for this condition, medicine will be prescribed. Cyclospora will go away without medication, but it could take four to six weeks and there is a risk of dehydration.
“People who are immunocompromised or take medications to suppress their immune system are encouraged to seek care immediately because, for them, the diarrhea will not improve without treatment.”
Wade Syers is a food safety specialist with Michigan State University Extension.
Contact: syerswad@msu.edu
“In the United States, illnesses have been linked to contaminated fresh fruits and vegetables, especially produce that’s eaten raw. The good news is there are steps you can take to reduce your risk. The CDC recommends washing your hands before and after handling fresh produce, rinsing fruits and vegetables thoroughly under running water before eating, cutting or cooking them, and using a clean produce brush on firm produce such as melons and cucumbers.”
Nishita D’Souza is an assistant professor in the Department of Fisheries and Wildlife. Her research focuses on a One Health approach, applying culture and molecular based environmental and water quality monitoring tools to understand the burden of human pathogens and improve the safety of water, the sustainability of resources and the monitoring of public health impact.
Contact: dsouzan1@msu.edu
“Our laboratory currently monitors wastewater in Michigan communities, supporting the state’s public health programs. We have access to advanced molecular systems, which we have applied to test for a vast number of targets. We are working on validating and optimizing existing testing protocols for viruses and fungi to hopefully help support monitoring for cyclospora through wastewater. If successful, wastewater monitoring could help identify impacted areas in the state and provide key indications of areas where clinical testing and resources can be prioritized. Wastewater could also help monitor how interventions being suggested and implemented by health professionals are making a difference to keeping our communities protected from disease spread.”
Jade Mitchell is a professor in Biosystems and Agricultural Engineering at MSU. Her research focuses on pathogen transmission through environmental media, especially as it relates to food safety and water quality.
Contact: jade@msu.edu
“Cyclosporiasis is caused by ingesting food or water contaminated with the parasite cyclospora. It can cause severe gastrointestinal symptoms and result in dehydration from the diarrheal illness. Consumers should know that the parasite is more resistant than other foodborne pathogens, and simple washing is likely not enough to remove it from fresh produce. The illness can be treated with antibiotics, and medical care is recommended if presumed exposure and related symptoms exist.”
John Besley, Ellis N. Brandt Professor of Public Relations in the MSU College of Communication Arts and Sciences, studies how people think about science and scientists, and how scientists can communicate more effectively with the public. He has authored two books on science communication and is a former editor of the journal Risk Analysis.
Contact: jbesley@msu.edu
“Food scientists at universities and in government agencies across the country are working hard to both understand this outbreak and help get it under control. There are still many unknowns, but scientists shouldn’t be afraid to talk about this uncertainty while still providing the best advice they can and emphasizing their commitment to helping address the threat. More broadly, events like these remind us that we all benefit when scientists have the resources needed to both conduct research and communicate effectively.”