CDC Warning on Cyclosporiasis Cases in Multiple States

The CDC issued a Health Advisory notifying clinicians, public health practitioners, and laboratorians of an increase in domestically acquired cyclosporiasis cases across multiple states. Since May 1, 2026, the CDC has received reports of 1,645 confirmed domestic cases from 34 states and is evaluating more than 5,100 additional cases to determine whether they were domestically acquired.

Among the 1,645 confirmed case-patients with available information, 141 (9%) were hospitalized, and no deaths were reported. The CDC said cyclosporiasis is often underdiagnosed and underreported, meaning the actual number of illnesses is likely higher. The agency is working with the FDA and state and local health departments to investigate multiple clusters and identify potential sources.

Cyclosporiasis is a gastrointestinal illness caused by the microscopic parasite Cyclospora. Infection can result from consuming contaminated food or water, and previous outbreaks have been linked to fresh produce. Common symptoms include frequent watery diarrhea, loss of appetite, weight loss, bloating, nausea, and fatigue. Without treatment, symptoms may remit and relapse for a month or longer.

The CDC advised clinicians to consider cyclosporiasis in patients with prolonged or relapsing watery diarrhea during the May-through-August season, even without international travel. The agency also recommended asking patients with suspected or confirmed infection about recent food and travel exposures. Because routine ova and parasite examinations may not reliably detect Cyclospora, The CDC advised clinicians to specifically request testing for the parasite. Molecular (PCR-based) testing may improve detection where available. Laboratories were advised to promptly report confirmed results to the ordering clinician and appropriate health department according to jurisdictional requirements. 

The CDC recommends treatment with 7-10 days of trimethoprim-sulfamethoxazole (TYMP-SMX) for confirmed cases in immunocompetent adults and children older than 2 months, with treatment duration based on age and immune status and that longer courses may be considered for immunocompromised patients.

Source: Centers for Disease Control and Prevention. Domestically acquired cyclosporiasis cases in multiple U.S. states, 2026. Health Advisory. Centers for Disease Control and Prevention; July 14, 2026. Accessed July 16, 2026.