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  1. FDA Voices: Perspectives From FDA Leadership and Experts

FDA Arming Itself with Science to Help Prevent Cyclospora Infections


View FDA Cyclospora research photos on Flickr.


By: Steven Musser, Ph.D., Deputy Director for Scientific Operations, FDA’s Center for Food Safety and Applied Nutrition (CFSAN) and Alexandre da Silva, Ph.D., Lead Parasitologist at CFSAN’s Office of Applied Research and Safety Assessment

Cyclospora cayetanensis is so small that it can only be seen with a microscope. However, there is nothing small about the U.S. Food and Drug Administration’s work to help protect consumers from the foodborne illness that this parasite can cause.

Cyclosporiasis is an intestinal illness caused by consumption of foods, mainly fresh produce, that are contaminated with Cyclospora. The FDA has been working to help prevent contaminated product from reaching consumers, gathering the scientific knowledge that will help to better detect the parasite in food and the environment, and gathering data to better understand how food is contaminated by the parasite and help prevent contamination in the future. We’re also sharing what we know with stakeholders in the public and private sectors.

The Centers for Disease Control and Prevention is the federal agency that tracks U.S. cases of cyclosporiasis, and the latest data makes it clear that the number of cases continues to rise, especially during the peak months of May through August. 

Recent advances in diagnostic detection methods, a broader awareness of this parasite in the medical community, and increased testing of ill patients may have been partially responsible for the increase in reported cases. Still, the CDC data shows that more efforts are needed to prevent future Cyclospora illnesses.

Because several past outbreaks have been associated with fresh herbs, the FDA has been conducting surveillance sampling of fresh cilantro, parsley and basil. A quarterly update on this food surveillance study was released today. As this effort continues, our goal is to collect enough samples to provide a precise estimate of the prevalence of contamination of Cyclospora in our food supply, enabling us to better understand our vulnerability to Cyclospora contamination.     

The FDA is also acting on what we already know about where Cyclospora is found and how contamination can be prevented.   

Taking Steps to Protect Consumers

Historically, Cyclospora has often been associated with imported produce. Recognizing that the increasingly global nature of the food supply is likely a factor contributing to rising numbers of Cyclospora infections, the FDA is taking steps to keep contaminated produce grown in other countries from reaching U.S. homes. Due to an established risk of contamination, the FDA currently has import alerts in place related to Cyclospora, including one for raspberries from Guatemala and another for cilantro from Mexico. Import alerts inform the FDA's field staff and the public that the agency has enough evidence to allow for Detention Without Physical Examination (DWPE) of products that appear to be in violation of the FDA's laws and regulations. 

In 2019, 10% of the Cyclospora infections reported between May and August were linked to a multi-state outbreak associated with fresh imported basil that started in mid-June and was declared over in October. FDA increased its screening at the border of basil exported by the company tied to the outbreak before the company voluntarily recalled its product and ceased shipping while corrective measures were implemented.

The FDA is also tracking contamination in domestically-grown produce. The first confirmed evidence of Cyclospora in domestically grown produce was detected in 2018 in cilantro, a finding not associated with an outbreak of illnesses. As with bacterial pathogens, if the parasite is found on produce, the FDA follows up with inspections and sampling, working with the business to take the actions needed to protect public health.

The FDA has been reaching out to farmers to increase awareness of Cyclospora and actions that can be taken on the farm to reduce the likelihood of contamination. For example, ways to control sources of contamination include proper use, maintenance and cleaning of toilet and handwashing facilities. We created education and outreach materials for farmers, including the Cyclosporiasis and Fresh Produce Fact Sheet

The FDA’s Produce Safety Network, staffed by regionally based experts, is also in constant communication with state agencies involved with produce safety and with the farming community to deliver up-to-date information about this parasite.

Scientists on the Foodborne Parasitology Research Team at FDA’s Center for Food Safety and Applied Nutrition
Alexandre da Silva, Ph.D., (foreground) working with fellow scientists on the Foodborne Parasitology Research Team.

View this and other FDA Cyclospora research photos on Flickr.


What We Are Pioneering, as an Agency

Cyclospora outbreaks present some unique challenges when it comes to utilizing genetic information to identify whether individual cases might stem from the same food. In late 2014, the FDA’s Center for Food Safety and Applied Nutrition established a Foodborne Parasitology Research Program, and in collaboration with the CDC, has been sequencing the genomes of several different strains of C. cayetanensis, enabling the development of genetic typing methods. In 2016, we created a genome database named “CycloTrakr” to be used as a public repository of genomic data at the National Center for Biotechnology Information (NCBI). This is an important first step towards the goal of linking, in real-time, the genetic fingerprints of Cyclospora in contaminated food and sick people to pinpoint the source of the outbreaks.

The agency has also pioneered ways to detect the parasite, developing and validating new methods to test for Cyclospora in produce and water. The first of these new methods was used for the first time in 2018 to confirm the presence of the parasite in a salad mix product tied to an outbreak that sickened hundreds of people. 

In July 2019, the FDA made its second major advance in Cyclospora detection, completing studies that resulted in a novel, validated method to test agricultural water for the presence of the parasite. Water used on farms is a potential source of the contaminants that cause foodborne illnesses. Analysts from FDA laboratories are being trained in the use of this method for regulatory testing. 

Supporting Continuous Improvements

The agency is increasing the capacity of laboratories to detect Cyclospora. A training program was launched in 2018 in FDA laboratories and in state laboratories that are part of the Food Emergency Response Network (FERN), a secure laboratory system for federal, state and local agencies engaged in food safety and defense. This increased capacity will decentralize and expedite our analytical response during outbreak investigations.   

Each year, the Outbreak Evaluation team in FDA’s Coordinated Outbreak Response and Evaluation network reviews its activities for lessons learned in an effort to increase our scientific knowledge and to develop improved mitigation strategies against this parasite. After the 2018 outbreaks, the FDA created a C. cayetanensis Task Force in which FDA and CDC representatives focus on developing strategies to reduce the public health burden of foodborne illness caused by Cyclospora. A research collaborative agreement is being developed to boost the scientific collaboration between the FDA and the CDC and harmonize the use of methods to genetically type C. cayetanensis. Combined with epidemiologic and traceback data, this will enable both agencies to find and link sources of outbreaks more rapidly. 

The produce industry also has an important role in helping to protect consumers from Cyclospora. In June 2019, an industry-established Blue-Ribbon Panel on the Prevention of Foodborne Cyclospora Outbreaks stressed the importance of health and hygiene awareness for farm personnel. The FDA has supported the work of this panel by providing technical assistance from agency experts. 

By approaching this public health hazard from many directions, the efforts by the FDA and our partners will ultimately converge on a path that will help significantly reduce the threat of this illness.

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