Analysis of Current Research and Identification of Known Vectors for C. cayetanensis and Vectors for Contamination by C. cayetanensis

Outbreaks of Cyclospora cayetanensis (C. cayetanensis) have occurred in the USA nearly every year since 2000. Although these outbreaks have historically been connected to imported produce or international travel, the 2018 spike in cyclosporiasis illnesses was connected to domestically grown produce. Foreign research on the public health risk of domestic C. cayetanensis, while informative, did not identify all vectors pertaining to sources of infection in the USA. Therefore, the objective of this review paper was to identify the root causes of the transmission of this protozoan pathogen to humans. Twenty-six papers spanning the past 12 years were analyzed along with product testing results from the FDA between 2018 and 2019, and epidemiological data from the CDC on the two domestic (USA) C. cayetanensis outbreaks implicated in 2018. This review found that public health risk associated with domestic sources of infection by C. cayetanensis was difficult to quantify due to insufficient research. Future studies should focus on transmission routes in the domestic produce supply chain, starting with growing regions where previously contaminated product was sourced.