From the Health department:
McHenry County Department of Health investigating increase in cyclosporiasis cases
MCHENRY COUNTY, IL –The McHenry County Department of Health (MCDH) is investigating an increase in reported cases of cyclosporiasis in McHenry County. Since June 25, the MCDH has identified 61 cases of cyclosporiasis, more than five times the number of cases reported during the same timeframe in 2025. The investigation remains active, and the number of reported cases may continue to change.
Symptoms of cyclosporiasis typically begin about one week after exposure and commonly include watery diarrhea, loss of appetite, weight loss, stomach cramps or bloating, nausea, fatigue, and low-grade fever. Without treatment, symptoms may last for several weeks or longer, with periods of improvement followed by recurrence.
Because the illness can cause prolonged diarrhea, there is a risk of dehydration. Individuals experiencing decreased urination, dizziness, or headache after ongoing diarrhea should seek medical treatment for dehydration. Anyone whose diarrhea persists for more than a couple of days is encouraged to contact their primary care provider or seek medical attention for evaluation, testing, and appropriate treatment.
Cyclosporiasis cases are associated with consumption of contaminated fresh produce or water. Historically, cyclosporiasis outbreaks have been linked to a variety of fresh produce items, including leafy greens such as lettuce, fresh herbs, snow peas, green onions, and berries. At this time, no specific source has been identified in the current, ongoing investigation.
The MCDH encourages residents to follow routine food safety practices to help reduce the risk of foodborne illness by:
- Rinsing all fresh fruits and vegetables under running water and gently scrubbing or wiping produce before eating, cutting, or cooking.
- Scrubbing firm produce, such as melons and cucumbers, with a clean produce brush.
- Washing and sanitizing cutting boards, utensils, containers, and other food contact surfaces after preparing fresh produce.
- Washing hands thoroughly with soap and water before preparing food, after handling fresh produce, after using the restroom, and anytime hands may become contaminated.
With no specific food source identified, consumers can reduce, but not completely eliminate, their risk by carefully washing, preparing, and storing fresh produce. When appropriate, cooking produce to an internal temperature of 158°F is more effective than washing alone because it inactivates Cyclospora.
The MCDH will continue to monitor the situation and provide updates as additional information becomes available.
