The Delaware Division of Public Health (DPH) is sending this health advisory to alert clinicians and health care partners of domestically acquired cyclosporiasis in multiple U.S. states.

Summary   

DPH is sending this health advisory to alert clinicians and health care partners. Since May 1, 2026, The Centers for Disease Control and Prevention (CDC) has received reports of 1,645 confirmed domestic cases of cyclosporiasis and is aware of more than 5,100 cases that require further analysis to confirm the illness as domestically acquired cyclosporiasis. This is substantially higher than the 249 cases reported nationally by this same time last year. Of the 1,645 case-patients with available information, 141 (9%) were hospitalized, and none have died. CDC, the U.S. Food and Drug Administration (FDA), and state and local health departments are working together to investigate multistate outbreaks of Cyclospora infections and to identify the sources of illness. Because cyclosporiasis is often underdiagnosed and underreported, the true number of illnesses is likely higher than what has been reported to CDC.

At this time, DPH has identified one internationally acquired case and one domestically acquired in Delaware. DPH is recommending that clinicians and health care providers consider signs and symptoms of cyclosporiasis, as early diagnosis and treatment can improve the outcome.

Cyclosporiasis is a gastrointestinal illness caused by the microscopic parasite Cyclospora. People can become infected by consuming food or water contaminated with the parasite. This illness is not usually spread directly from person to person.

Background

As of May 1, 2026, 1,645 lab-confirmed cases were reported to CDC in people who acquired cyclosporiasis in the United States. Cases were reported by 34 states. Case-patients developed illness after eating food in the United States and did not report any travel during the previous 14 days. Case-patients ranged in age from 2 to 95 years, with a median age of 44 years, and 56% were female. Of 1,645 case-patients with information available, 141 (9%) were hospitalized. No deaths have been reported. This is substantially higher than the 249 cases reported nationally from May 1 to July 16, 2025.

CDC is working closely with FDA and state health authorities to investigate multiple clusters of cyclosporiasis. CDC has posted an investigation notice about an outbreak with more than 400 cases in at least four U.S. states that appear to be epidemiologically linked, suggesting that there could be a common source of these infections.

Symptoms of cyclosporiasis typically begin about one week after exposure. Onset of systems can occur two to 14 days after being exposed. The most common symptoms include watery diarrhea, which can be frequent, along with loss of appetite, weight loss, bloating, nausea, and fatigue. Less common symptoms include low-grade fever and vomiting. Without treatment, symptoms can follow a remitting-relapsing course that can last from a few days to a month or longer. Illness can be severe but is not usually life-threatening. Complications can include malabsorption, cholecystitis, and reactive arthritis. Laboratory detection of Cyclospora in stool can be challenging even in symptomatic patients, and standard ova and parasite exams might not detect it reliably. Clinicians should specifically request diagnostic testing for Cyclospora when it is clinically suspected.

Reporting   

Delaware physicians, laboratories, and other health care providers are required by regulation to report cyclosporiasis cases to the DPH Office of Infectious Disease Epidemiology (OIDE). Reporting enables appropriate public health follow-up for patients, helps identify outbreaks, and provides a better understanding of disease trends in Delaware. Cases can be reported to DPH OIDE by calling 302-744-4990 (during normal business hours) or 1-888-295-5156 (outside of normal business hours). You may also complete a Notifiable Disease Report PDF Form and fax the form to DPH at 302-622-4149 or email reportdisease@delaware.gov. The form can be found online at https://dhss.delaware.gov/dph/homepage/about/sections/ehdishome/epi/report-disease/.


Recommendations  for Clinicians

• Consider cyclosporiasis in patients presenting with prolonged or relapsing watery diarrhea, particularly during the May to August cyclosporiasis season, even without a history of international travel.

• Ask patients with suspected or confirmed cyclosporiasis about their recent food and travel history to assist local investigations.

• Specifically request Cyclospora laboratory testing on stool specimens because routine ova and parasite (O&P) examinations might not reliably detect the parasite. Consider molecular (PCR-based) diagnostic testing where available, because it can improve detection.

• Treat confirmed cases of cyclosporiasis with seven to 10 days of trimethoprim-sulfamethoxazole (TMP-SMX) for immunocompetent adults and children over age 2 months; consider longer courses for patients with immunocompromising conditions. Consult current CDC clinical guidance for recommended dosing.

• Advise patients to stay well hydrated, especially if diarrhea is frequent or severe.

• Contact the Council for State and Territorial Epidemiologists (CSTE) clinician line after hours for on call support if needed.

• Cyclosporiasis is a reportable disease in Delaware. All cases must be reported to DPH OIDE by calling 302-744-4990 (during normal business hours) or 1-888-295-5156 (outside of normal business hours).

Recommendations for Disinfecting Cyclospora in Health Care Settings

• Given the typical lifecycle of Cyclospora, person-to-person transmission is unlikely, even within health care settings. If an affected patient is continent of stool, the level of environmental contamination is probably small.

• Cyclospora is unlikely to be killed or inactivated by routine chemical disinfection. No EPA-registered disinfectant products have been demonstrated to be effective against Cyclospora. When affected patients are incontinent or diapered, the risk of contamination of health care surfaces might be higher. Facilities should clean surfaces initially with a detergent to remove any visible soil and scrub the surfaces thoroughly. After this cleaning, an EPA-registered hospital disinfectant should be used. Immediately after cleaning, health care personnel (HCP) should remove gloves used during cleaning and clean their hands.

• HCP should always use standard precautions, including wearing gloves when there might be direct contact with feces. A gown, facemask, and eye protection, or face shield should be used if splashing might occur. Hand hygiene should be performed before and after every patient contact. If hands are visibly soiled, HCP should wash them with soap and water, scrubbing vigorously for 15 to 20 seconds. If hands are not visibly soiled, alcohol-based hand sanitizer may be used. For patients with gastroenteritis who are diapered or incontinent of stool, HCP should use contact precautions when providing direct patient care in health care settings.

Recommendations for the Public

• Visit a clinician if you have prolonged or watery diarrhea, especially if it lasts more than a few days.

• Reduce your risk by thoroughly washing fresh produce under clean running water before eating and by following safe food handling practices. Be aware that chemically disinfecting or sanitizing produce might not fully eliminate Cyclospora. It is important to thoroughly wash produce even if it is labeled as pre-washed.