How the U.S. Cyclospora Outbreak Reflects a Strained National Foodborne Illness Surveillance System

The current surge of cyclosporiasis cases across the U.S., including a Midwestern outbreak cluster of hundreds of infections, underscores growing concerns about the capacity of the under-resourced U.S. foodborne illness surveillance system, with public health experts arguing that delays in outbreak detection and source identification reflect mounting pressure on federal and state public health infrastructure.
During a June 16 briefing hosted by George Washington University's Institute for Food Safety and Nutrition Security (IFSNS), experts representing academia and consumer advocacy discussed the current challenges of investigating the growing number of Cyclospora cayetenensis infections and warned that continued failure to invest in public health could hamper future responses to foodborne illness outbreaks.
Resource Constraints Are Slowing Outbreak Response, Sowing Confusion
Sarah Sorscher, J.D., M.P.H., Director of Regulatory Affairs at the Center for Science in the Public Interest (CSPI), said delays in reporting between state health departments and the U.S. Centers for Disease Control and Prevention (CDC) contributed to public confusion during the early stages of the outbreak.
Michigan, which has reported more than 4,000 cyclosporiasis cases as of July 16, began issuing public health notices about the situation nearly two weeks before CDC published its own outbreak alert. During that period, reporters often looked to CDC's national Cyclospora surveillance data, which included unrelated cases from across the country, and did not align with more recent figures from Michigan or other affected states.
"The biggest issue is that neither CDC nor its state partners have identified the food or water source that caused this large outbreak," Ms. Sorscher said. "There is no way then for consumers to eliminate that pathogen on the fresh produce that we have other than by cooking it."
She stressed that the current situation should not be interpreted as a failure of CDC investigators.
"This confusion that we're seeing is not due to any lack of skill or dedication by the CDC staff," Ms. Sorscher said, adding that investigators have continued working under increasingly difficult conditions while facing staffing reductions and growing workloads. "These programs are completely overwhelmed by the scale and scope of the work."
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Barbara Kowalcyk, Ph.D., M.A., Associate Professor at the George Washington University Milken Institute School of Public Health, described the outbreak as "a symptom of potential system vulnerabilities."
Panelists pointed to significant workforce losses under the Trump Administration, stagnant public health funding, and reductions in allocations to state and local health departments as factors increasingly straining foodborne illness surveillance and outbreak response.
Ms. Sorscher noted that CDC's food safety budget has failed to keep pace with inflation and said the agency reportedly fulfilled only about 40 percent of requests for support from state and local partners during the previous year.
Surveillance Is the Foundation of Prevention
Throughout the discussion, speakers emphasized that surveillance systems remain one of the most effective public health tools for preventing foodborne illness. Surveillance is the starting point for identifying outbreaks, determining root causes, improving food safety systems, and ultimately, preventing future illnesses.
Don Schaffner, Ph.D., Distinguished Professor and Extension Specialist in Food Science at Rutgers University, warned that weakening surveillance systems could have long-term consequences. "I think cuts at the federal level will weaken our ability to manage risks from [C. cayetenensis]," he said.
The experts cited estimates suggesting that every $1 invested in CDC’s PulseNet—a national laboratory network that connects foodborne, waterborne, and related illnesses to detect outbreaks—saves Americans an estimated $70 in foodborne illness-related costs and that the network prevents thousands of illnesses annually through earlier outbreak detection and response.
Notably, in 2025, C. cayetenensis was dropped from the list of pathogens included in CDC's Foodborne Diseases Active Surveillance Network (FoodNet), which is a collaborative program between federal and state agencies that conducts active surveillance for specific foodborne pathogens. Dr. Kowalcyk emphasized that FoodNet was not designed to detect outbreaks but rather to monitor long-term trends in foodborne illness. She noted that the elimination of Cyclospora from FoodNet surveillance resulted in the loss of valuable data that can help public health officials understand how the current outbreak compares with historical trends.
Calls to Restore U.S. Food Safety Surveillance Programs
In November 2025, a coalition of more than 20 organizations, including George Washington University’s IFSNS and CSPI, sent a letter to U.S. Health Secretary Robert F. Kennedy Jr. urging adequate funding for FoodNet, as well as a 50 percent ($36 million) increase in funding for the CDC Food Safety Program.
The letter states, “The Food Safety Program at CDC has been chronically under-funded, particularly in the last few years; it received only $72 million in Fiscal Year 2024. This amount is wholly inadequate to maintain FoodNet, including the continued reporting of the full scope of pathogens historically tracked by FoodNet partners, along with all other food safety work at CDC, which also passes through grants to state departments of health to fund epidemiology and laboratory work needed to solve outbreaks.”
Additionally, in a July 14 letter, U.S. Senator Amy Klobuchar (Democrat-Minnesota) urged CDC to restore FoodNet and other food safety programs in light of the current cyclosporiasis situation. “Cuts to these programs are impacting our nation's ability to prevent, detect, and contain foodborne illnesses and protect public health," she wrote.
Why Cyclospora Outbreaks Are Difficult to Solve
Craig Hedberg, Ph.D., Professor in the Division of Environmental Health Sciences at the University of Minnesota, explained that Cyclospora outbreaks are particularly difficult to investigate because of the parasite's biology.
Unlike many bacterial foodborne illnesses, C. cayetenensis has a relatively long incubation period. Investigators often must reconstruct foods consumed over a two-week period, identify common restaurants or grocery stores among cases, and determine whether multiple clusters are linked to the same contaminated product.
"Although Cyclospora is a nationally notifiable disease, reporting is an individual state requirement," Dr. Hedberg said, noting that outbreak investigations require extensive coordination among local, state, and federal public health agencies.
Investigations often begin at the local or state health department level. Epidemiologists interview patients to identify common food exposures and potential clusters, while laboratories analyze clinical samples and public health agencies share data across jurisdictions. Once a likely source is identified, the U.S. Food and Drug Administration (FDA) and state departments of agriculture can conduct traceback investigations to determine where contamination occurred.
The Potential Role of Improved Testing in Rising Cyclosporiasis Rates
Dr. Hedberg also suggested that the year-over-year increase in reported Cyclospora infections in the U.S. could, in part, be a result of improved diagnostic testing. The growing use of culture-independent diagnostic tests (CIDTs), including multiplex polymerase chain reaction (PCR) panels capable of detecting numerous pathogens simultaneously, has made cyclosporiasis cases more likely to be identified than they were a decade ago.
Domestic cases of Cyclospora infections more than doubled from 537 in 2016 to 1,194 in 2017, and then nearly tripled to 3,519 cases in 2018. By 2023, there were nearly 3,000 cases of cyclosporiasis reported in the U.S.
However, scientists continue to face major knowledge gaps about C. cayetenensis, said Dr. Schaffner. Questions about Cyclospora for which researchers do not yet have the answers include: why infections peak seasonally, how produce most commonly becomes contaminated, and what environmental factors influence oocyst development. Scientists are also still working to better understand waterborne transmission, dose-response relationships, and rapid detection methods.
What Should Consumers Do? Uncertainty Creates Public Communication Challenges
Beyond the scientific investigation, panelists said the outbreak highlights the challenge of communicating uncertainty to consumers and described how information delays inherent to complex outbreak investigations can erode consumer confidence in food safety. Without identifying a contaminated food source for consumers to avoid, public health agencies have limited evidence-based recommendations they can provide, beyond general food safety advice.
The discussion also underscored the limitations of consumer interventions once fresh produce becomes contaminated with C. cayetenensis. Dr. Schaffner said handwashing and washing fresh produce are "not terribly effective" against the parasite—despite some messaging that has been circulating stating otherwise (for example, U.S. Agriculture Secretary Brooke Rollins told The Hill on Wednesday that “washing your fruit and vegetables, being diligent in where you are” is the best way for consumers to stay safe). Cooking is the only way to reliably eliminate the parasite on contaminated food.
Panelists said these realities illustrate why timely surveillance and source identification are critical. When investigators cannot identify the contaminated product, consumers have few practical actions available to reduce their risk beyond following routine food safety practices and staying informed as new information becomes available.
Some consumers may be dissuaded from eating fresh produce while investigators continue searching for the outbreak source. The experts agreed that this may be a negative public health consequence of murky details and incomplete media reporting as the outbreak remains unsolved.









