Cyclospora cayetanensis infection: current insights into foodborne outbreaks, diagnostic challenges, molecular epidemiology, and future directions.

Cyclospora cayetanensis causes prolonged or relapsing watery diarrhea and is an important cause of foodborne outbreaks, most often associated with contaminated fresh produce. Recent multistate outbreaks in the United States have highlighted how short product shelf life, complex supply chains, incomplete ingredient-level exposure data, and limited availability of implicated foods hinder timely source attribution. This review examines foodborne outbreak epidemiology, clinical and diagnostic challenges, molecular epidemiology, treatment, and priorities for surveillance and research. PubMed/MEDLINE was searched through August 27, 2026, supplemented by reference screening and targeted searches of public health, regulatory, governmental, and Taiwan-based academic sources. Available evidence shows that molecular assays and genotyping improve case detection and cluster identification, but their interpretation depends on organism burden, assay design, specimen quality, detailed epidemiological interviews, and product traceback. Presumptive molecular findings generated by non-species-specific or insufficiently validated assays should be distinguished from species-confirmed results, and molecular clustering should not be considered equivalent to source attribution. Trimethoprim-sulfamethoxazole remains the treatment of choice, whereas effective alternatives for patients unable to receive sulfonamides are lacking. In Taiwan, currently available evidence remains insufficient to define the burden of cyclosporiasis and the extent of local transmission. Future priorities include harmonized diagnostic and reporting criteria, validated food and environmental testing, improved molecular resolution, and risk-based surveillance linking clinicians, reference laboratories, epidemiological investigators, and food-safety authorities.