In partnership with the Center for Produce Safety, researchers from the University of Georgia are working on a project to identify potential sources of the protozoan pathogen Cyclospora cayetanensis.
The project, “The prevalence of Cyclospora in water and produce,” seeks to provide industry members a science-based picture of the presence of Cyclospora, the organism’s seasonality, and where it potentially could be located.
The results also may help industry make more informed decisions about sampling in potentially higher-risk areas and months.
Ynés Ortega is leading the research and says that it is designed to complement previous and current Center for Produce Safety funded work on the emerging foodborne pathogen.
Because the pathogen is endemic in many countries, Cyclospora was thought of as a problem linked to imported produce. But recent outbreaks in the United States tied to domestic produce have changed those beliefs. This is timely research as this year’s Fresh Express Cyclospora outbreak showed that the industry has a way to go to prevent these types of outbreaks
2020 Fresh Express outbreak
As of the most recent update from the CD,C on Sept. 23, 2020, a total of 701 people had confirmed Cyclospora infections associated with this Fresh Express bagged salad outbreak. They were reported in 14 states: GA, IL, IA, KS, MA, MI, MN, MO, NE, ND, OH, PA, SD, WI.
Cyclospora is a bit of an enigma, Ortega said. Unlike many other bacterial foodborne pathogens, there is no water treatment for Cyclospora. Preventing the microorganism from potentially contaminating produce in the field is key to avoiding outbreaks.
“All of those treatments they’re using cannot kill Cyclospora,” she said. “We don’t have an effective control point when it comes to processing, so we really, really need to focus 100 percent on what’s happening in the field.”
Cyclospora cayetanensis is a parasite composed of one cell, too small to be seen without a microscope. This parasite causes an intestinal infection called cyclosporiasis.
According to the CDC, the parasite is spread by people ingesting something — such as food or water — that was contaminated with feces. Often such contamination cannot be seen without a microscope. Cyclospora needs typically, at least one to two weeks after being passed in a bowel movement to become infectious for another person. Therefore, it is unlikely that Cyclospora is passed directly from one person to another.
Ortega explained that Cyclospora cannot reproduce in the environment and needs a human host to complete the cycle. But the complex reproductive cycle also complicates laboratory assays and confirmation.
Researchers involved in this project are using molecular tests to minimize the chances of false positives. The multiple tests also provide a more detailed genetic fingerprint that could possibly be used to trace the pathogen’s origin. That information can also be used to help investigators during outbreaks.
Finding Cyclospora DNA in a sample means simply that the DNA is present, but it doesn’t necessarily mean it’s viable or infectious.
“The more information, the better,” she said. “We’re using one of these tests to find the positive samples and then the other test to confirm and to add more information. That way we get a better idea of what’s going on.
“There are other pathogens that are very closely related to Cyclospora cayetanensis. That’s why we’re very careful just to make sure if we call it Cyclospora, it has to be Cyclospora.”
Past epidemiological studies have found that Cyclospora is seasonal, with the peak period in the United States from June through August. The same type of peaks are seen in Mexico and Guatemala as well as a number of other countries.
“It shows up at certain times of the year, and the cycle repeats every single year,” Ortega said. If research shows the presence of Cyclospora in surface waters in Florida or California, it could help the industry identify potentially high-risk months.
Ortega hopes her research leads to simple rapid water sampling and testing methods for the produce industry to use for Cyclospora.
“You can have something that’s really good, but if it’s so unpractical to do, it won’t get done,” she said. “We’re trying to make this user-friendly because we want people to use it.”
The CPS has produced a short video on this research project. The video can be viewed here.
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