FDA Grand Rounds: Cyclospora cayetanensis

Identifying Cyclospora in the Environment

Given the issues encountered by FDA analysts in processing water samples from the 2013 outbreak related to organic matter in the water supply, the FDA investigated using ultrafiltration techniques for identifying Cyclospora in water sources. Thus far, preliminary research using this method, which is presently undergoing a verification process, demonstrates that it can detect 6 C cayetanensis oocysts per 10 mL of agricultural water. However, there is still a significant gap in knowledge of how water is contaminated with Cyclospora.

To address this, the FDA is currently conducting an investigation using surfaces that are artificially/intentionally contaminated with stool samples positive for C cayetanensis oocysts and the ability of this artificial surface (ie, a glove) to transfer the oocyst to a water source. The researchers are then applying the ultrafiltration technique to evaluate the water source and understand the transmission processes. Using ultrafiltration, researchers found that there was a detectable amount of C cayetanensis in a 10 L source of waterthat was touched for 5 seconds with a 0.05 g sample of C cayetanensis-positive stool.

Future Research Challenges

The FDA recommends the development of new generation detection and genotyping techniques, specifically ones that are sensitive to low concentrations of C cayetanensis oocysts. The FDA also recommend continued work on the aforementioned database and ultrafiltration method. Lastly, further research is significantly needed to investigate the process of C cayetanensis oocyst sporulation, as this is its most virulent stage. If sporulation can be stopped, then there may be a way to control Cyclospora outbreaks.

Reference

Da Silva AJ. Cyclospora cayetanensis: the crossroads between the scientific advances and knowledge gaps. FDA Grand Rounds. Presented June 13, 2019. Accessed June 13, 2019.