IDPH Health Advisory

Date Issued May 4, 2026

Author Communicable Disease Section

• Summary and Action Items
• Alert providers and local health departments (LHDs) that Cyclospora season begins May 1
• Request LHDs conduct enhanced investigation of domestically acquired cases
•  Remind health care providers and laboratories about testing requirements to identify Cyclospora
•  Request laboratories forward clinical materials positive for Cyclospora to the IDPH Laboratory

Background

Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. Generally, there is a seasonal increase in reported cyclosporiasis infections during the months of May through August. Cyclospora outbreaks in the United States, including in Illinois, have been linked to various types of imported fresh produce. Cyclospora cases in the United States are also more commonly seen among persons who traveled internationally prior to illness onset.

IDPH and LHD Response

Cyclosporiasis is reportable to local health departments by health care providers and laboratories. Clinically compatible cases with a laboratory test that detects Cyclospora organisms or DNA in stool, intestinal fluid/aspirate, or intestinal biopsy specimens are considered confirmed cases. Local health departments should interview all laboratory confirmed and epi-linked probable cases of Cyclospora, regardless of when they became ill, with the standard questions for this disease and with the Cyclosporiasis National Hypothesis Generating Questionnaire (CNHGQ), available on the IDPH CD Cyclosporiasis Web Portal page. Completed questionnaires should be sent to the IDPH Communicable Disease Control Section through secure email to [email protected] or faxed to 217-524 0962. The CNHGQ used to interview cases of Cyclospora will be incorporated into the Cyclospora questionnaire within the new Illinois Disease Surveillance System (IDSS), anticipated for deployment in mid-July 2026. Upon IDSS deployment, LHDs will enter CNHGQ data into IDSS and will no longer need to complete the PDF version of the questionnaire.

IDPH, along with local health departments, will investigate cases through extensive case interviews, identify potential outbreaks, and work with federal partners to identify sources of exposure.

Potential Exposures

People can become infected with Cyclospora by consuming food or water contaminated with the parasite. In the United States, foodborne outbreaks of cyclosporiasis have previously been linked to various types of imported fresh produce such as raspberries, basil, cilantro, snow peas, and lettuce.

Symptoms

The average incubation period is seven days but can range from two days to two weeks or more. Cyclospora can cause watery diarrhea, weight loss, fatigue, anorexia, nausea, and abdominal cramps. Symptoms can last for a few days to a month or longer. Symptoms may go away and come back again multiple times. Most people who have healthy immune systems will recover without treatment. However, there is an effective antibiotic, and clinicians should consider treatment of confirmed cases based on clinical status. Illinois Department of Public Health 525-535 W. Jefferson St. Springfield, IL 62761 dph.illinois.gov 217-557-2556 69 W. Washington St., Suite 3500 Chicago, IL 60602

Transmission

People can become infected with Cyclospora by consuming food or water contaminated with the parasite. Person-to-person transmission generally does not occur.

Diagnosis

Health care providers should consider Cyclospora as a potential cause of prolonged diarrheal illness. Cyclospora infection is diagnosed by examining stool specimens or with the use of culture-independent diagnostic tests on stool specimens. Clinicians should specifically request stool testing for Cyclospora, as testing is not routinely conducted in all laboratories. A single negative test result is not definitive to rule out Cyclospora infection. When clinical suspicion is high, multiple stool specimens should be submitted to increase the testing yield.

Laboratories: Cyclospora cayetanensis oocysts, which are 8-10 micrometers in diameter, can be detected by modified acid-fast staining of stool. Fluorescence microscopy also can be utilized for detection of oocysts, which are auto fluorescent. This link provides additional helpful tools to aid in the laboratory diagnosis of Cyclospora. Diagnosis using culture-independent diagnostic tests (CIDT), such as the BioFire® FilmArray® Gastrointestinal (GI) Panel (multiplex PCR), has become more common. Laboratories should forward clinical materials positive for Cyclospora to the IDPH Springfield or Chicago Laboratory until September 1, 2026.

Prevention

Avoiding food or water that may have been contaminated with feces is the best way to prevent cyclosporiasis. Consumers and retailers should always follow safe fruit and vegetable handling recommendations. Contact Health care providers and laboratories should contact their local health department with questions or to report cases. Local health departments should contact the IDPH CD Section at 217-782-2016 or [email protected] with any questions.