Health officials in McHenry County are on high alert following a dramatic surge in cyclosporiasis cases, reporting a spike that is more than five times higher than what was seen during the same period last year. Since June 25, the county health department has identified 61 confirmed cases of the parasitic infection. While investigators are working quickly to find the cause, they admitted on Friday that no single identifiable source of the outbreak has been found yet.
The illness generally manifests about a week after exposure and often presents as a grueling cycle of watery diarrhea, stomach cramping, nausea, and fatigue. Because symptoms can fluctuate—improving briefly before returning again—the condition can linger for several weeks if left untreated. Public health experts warn that prolonged diarrhea puts patients at a significant risk for dehydration, urging anyone experiencing dizziness or decreased urination to seek immediate medical care.
Historically, cyclosporiasis outbreaks have been traced back to contaminated water or fresh produce, specifically items like berries, snow peas, green onions and various leafy greens. With the current source still unknown, the health department is advising residents to be extra vigilant with their food preparation. They recommend rinsing all fruits and vegetables under running water and using brushes for firmer produce like cucumbers or melons. Sanitizing cutting boards and utensils after use is also strongly encouraged to prevent cross contamination.
While thorough washing helps reduce risk, officials noted that heat is the most effective defense against the parasite. Cooking produce to an internal temperature of 158 degrees Fahrenheit effectively inactivates cyclospora in a way that rinsing cannot. The McHenry County Department of Health stated they will continue monitoring new reports as the investigation evolves and promised to share further updates as soon as more information becomes available.