State health authorities have confirmed 240 cases of cyclosporiasis in Illinois as of Wednesday, with 21 people hospitalized, according to the Illinois Department of Public Health. The outbreak is part of a larger multi-state increase that has affected thousands of Americans this summer.
What is cyclosporiasis and who is affected
Cyclosporiasis is an intestinal infection caused by the microscopic parasite Cyclospora. The illness most commonly produces watery diarrhea, stomach cramps, bloating, gas and nausea. Although it is rarely fatal, the disease can produce prolonged symptoms and, in some cases, lead to complications that require hospitalization.
"Cyclosporiasis is not considered a deadly disease and is more of an inconvenience that in rare cases could have complications," said Dr. Emily Landon, an infectious diseases specialist at University of Chicago Medicine.
Illinois officials say the majority of people who have tested positive reported recent travel: 105 people traveled internationally and 111 traveled within the United States. For the remaining 24 cases, travel history is unclear.
Likely exposures and why cases spike in summer
Cyclospora spreads when people ingest food or water contaminated with feces containing the parasite’s oocysts. Fresh produce exposed to contaminated irrigation or wash water has been tied to previous outbreaks across the U.S., including packaged salads and berries.
- No single source has been pinpointed in Illinois for this surge.
- The parasite thrives in warm conditions, which helps explain a summertime rise in cases.
- The outbreak in Illinois mirrors wider national trends: the CDC has reported cases in dozens of states.
Federal data show more than 1,600 cases reported across 34 states, illustrating the outbreak’s broad footprint and the challenges of tracing produce linked to multiple distribution chains.
Testing, treatment and prevention
Health officials urge anyone experiencing ongoing diarrhea, stomach pain or related symptoms to contact their primary care physician or local health department to discuss testing. Prompt diagnosis helps public health authorities track the outbreak and identify potential common sources.
When it comes to treatment, medical providers typically prescribe specific antibiotics effective against cyclospora. Discussing recent travel and food exposures with clinicians can guide testing decisions.
Practical prevention tips from public health experts include:
- Wash fresh fruits and vegetables under running water before eating; do not rely on soap or commercial produce washes to eliminate parasites.
- Be cautious with prepackaged salads and ready-to-eat produce if local advisories mention potential contamination.
- Seek medical advice if gastrointestinal symptoms last more than a few days or are severe.
| Illinois cases | 240 |
| Hospitalized | 21 |
| Reported international travel | 105 |
| Reported domestic travel | 111 |
Officials continue to investigate and work with the Centers for Disease Control and Prevention to determine if a common food item or supplier is responsible. In the meantime, public health authorities emphasize testing, reporting of suspected cases and careful handling of fresh produce as the best immediate steps for reducing risk.
If you are symptomatic and have recently traveled or consumed fresh produce, contact your health care provider to discuss testing and treatment options. Local health departments can provide up-to-date guidance for your community.
