A recent joint publication between the U.S. Food and Drug Administration (FDA) and Rheonix Inc. has confirmed the efficacy of an assay to detect Cyclospora cayetanensis, developed under a Research Collaboration Agreement (RCA) between Rheonix and FDA’s Office of Applied Research and Safety Assessment (OARSA). The study, published in the journal Microorganisms, demonstrated that the fully automated Rheonix C. cayetanensis™ assay achieves consistent detection rates for C. cayetanensis in samples of high-risk fresh produce with low levels of oocysts, including matrices such as herbs, leafy greens, and berries.

C. cayetanensis is a parasite of increasing concern to food safety in the U.S., with foodborne outbreak investigations in 2018 revealing the risk of C. cayetanensis contamination of domestically grown produce, and more than 10,000 domestically acquired cases of cyclosporiasis being confirmed since 2018. The streamlined assay has the potential to be an effective tool for outbreak and surveillance for C. cayetanensis in produce.

The Rheonix C. cayetanensis assay is based on genetic targets developed and published by FDA, and is processed using Rheonix reagents and consumables on the Rheonix Encompass Optimum™ workstation. The joint study shows the integration and verification of FDA’s mitochondrial target into Rheonix’s fully automated and streamlined workstation, simplifying workflow by performing DNA isolation, polymerase chain reaction (PCR), hybridization, results visualization, and reporting of results. The fully automated method enables detection of low levels of C. cayetanensis in produce samples, saving approximately four hours of hands-on effort per 24-sample run, in comparison to the prior workflow.

The Rheonix assay is now available for use by food and environmental testing laboratories.

The FDA-Rheonix RCA was established in February 2023 to rapidly develop, test, and validate a fully automated screening assay that can detect low levels of C. cayetanensis in fresh produce, soil, and surface agricultural water. Joint development of the assay was announced in June 2023, and is an effort under FDA’s Cyclospora Prevention, Response, and Research Action Plan to “engage with industry, academia, and test kit companies to encourage the modification of available rapid test kits to specifically detect C. cayetanensis, and to develop industry best practices that can be used to test for C. cayetanensis.” The Rheonix assay design also addresses a U.S. Centers for Disease Control (CDC) proposal that detection assays capture additional Cyclospora species of potential public health concern.