Illinois cyclosporiasis outbreak grows to over 215 confirmed cases, public health officials say
The Illinois Department of Public Health said there are now more than 215 confirmed cases of cyclosporiasis, an illness from the parasite cyclospora, statewide.
As of Tuesday, IDPH confirmed 216 cases, including 95 acquired domestically and 96 among patients who traveled outside the U.S. So far, there have been 18 hospitalizations.
Cases have increased since last week, when IDPH reported 141 cases of cyclosporiasis
No deaths have been reported.
In neighboring Michigan, health officials are contending with a cyclosporiasis outbreak that has now topped 3,300 cases. That is the largest outbreak reported in the country. More than 30 U.S. states have reported cases since early May, including Indiana, Pennsylvania, West Virginia, New York, and Texas.
Cyclosporiasis can be contracted by consuming food or water contaminated with feces. It is the illness caused by the parasite cyclospora and is typically treated with the antibiotic Bactrim. According to the Centers for Disease Control and Prevention, the most common symptoms are frequent watery diarrhea, loss of appetite, bloating, nausea, and fatigue.
The number of cyclosporiasis cases are likely underreported because there is significant time between when the parasite is first consumed and when symptoms begin showing up. This makes the true number of cases in an outbreak – in the state and nationwide – more difficult to report as well.
"Anything in fresh produce is one of the hardest trackers, especially when symptoms are a week or more in longevity," said Brian Schaneberg, executive director for the Institute for Food Safety and Health at Illinois Tech.
The institute has homed in on foodborne outbreaks in the past, tracing an e. coli outbreak in 2024 to slivered onions on quarterpounders and liking airborne salmonella from a poultry facility to peaches several years prior. Now they're closely monitoring what could become the biggest cyclosporiasis outbreak on record.
"Cyclospora outbreaks in small scale happen every year in pretty much every state, just not to the scale that we're seeing right now, and so there's definitely learnings we're still trying to figure out," he said.
State health officials in Michigan say testing shows lettuce or salad greens as a potential source of the cyclosporiasis outbreak.
"Although we do not have a definite product identified as the source of the outbreak, we want to let Michiganders know what we have learned so far so they can take steps to protect their families," said Dr. Natasha Bagdasarian, chief medical executive. "Early information has shown lettuce as a common product that regularly comes up during the investigation. We will continue to provide updates as we learn more."
How to prevent cyclosporiasis
You can easily lower your exposure to the cyclospora parasite by washing your hands and surfaces doing food preparation, by washing raw ingredients in cold water, and by thoroughly cooking fruits and vegetables.
Vinegar does not kill cyclospora, but it could help clean some of them off. In 2021, researchers in Norway added one part vinegar to three parts water and tested that mixture to clean three types of parasites from raspberries and blueberries.
The researchers found the mixture overall removed more parasites from both berries, but not a significant amount more than cleaning the berries in a salad spinner. It did help clean the berries more than just running them under water.
The CDC also recommends cutting away any damaged or bruise areas on fruits or vegetables before preparing and eating, and refrigerating cut, peeled or cooked fruits and vegetables as soon as possible.
