A summer outbreak of cyclosporiasis, a parasitic infection spread via contaminated food and water, has spread across 31 U.S. states and sickened more than 3,000 people, leaving public health experts scrambling to identify its source and slow transmission amid unique investigative challenges and strained public health resources.
The illness, which is rarely fatal, is defined by its primary symptom: severe, watery diarrhea that strikes abruptly. As of current reports, Michigan has borne the brunt of the outbreak with more than 2,600 confirmed cases, followed by New York State with a smaller but still significant caseload. Despite weeks of investigation, health officials have not yet pinpointed the original contaminated source of the parasite, and have only issued general guidance to the public: thoroughly wash all produce, avoid certain high-risk fruits including raspberries, and cook vegetables thoroughly to destroy the pathogen.
Public health investigators have described tracing the parasite as an extraordinarily difficult task, compounded by multiple biological and systemic barriers. “This isn’t like detecting a needle in a haystack. It’s like detecting a microscopic portion of a needle in a haystack,” explained Steven Manderach, executive director of the Association of Food and Drug Officials, who previously addressed cyclosporiasis outbreaks as a food safety official in Iowa.
Biologically, the parasite’s long incubation period creates a major hurdle for investigators. Unlike most foodborne illnesses that cause symptoms within hours of consumption, cyclosporiasis takes one to two weeks to trigger illness in infected people, explained Jodie Guest, senior vice chair of epidemiology at Emory University’s Rollins School of Public Health. By the time most people seek care and report their illness, they often cannot recall every food they ate in the preceding two weeks, breaking a key link investigators rely on to trace contamination sources.
Testing for the parasite in food supplies is also far more labor-intensive and complex than testing for other common pathogens. To isolate cyclospora, investigators must wash massive quantities of potentially contaminated produce to collect any parasite particles present, then concentrate the sample before testing can begin. “You’d have to have truckloads of lettuce to get to that point,” Manderach noted. The broad geographic spread of cases, spanning 31 states, also suggests multiple contamination points in the national food supply, a factor that further complicates coordinated investigations.
Many public health experts point to recent federal budget and staffing cuts to U.S. Department of Health and Human Services (HHS) agencies as a critical additional barrier to solving the outbreak. As part of Elon Musk’s Department of Government Efficiency cost-cutting initiative, Health Secretary Robert F. Kennedy Jr has implemented widespread cuts that have reduced capacity for key foodborne illness surveillance programs. Most notably, the Foodborne Diseases Active Surveillance Network (FoodNet)—a federal program that previously tracked cyclospora, salmonella, listeria and other pathogens nationwide—scaled back monitoring last year to only track two pathogens, ending its systematic surveillance for cyclospora.
In an internal memo to the state of Connecticut obtained by NBC News, the CDC acknowledged that “Funding has not kept pace” with the resources required to run the full FoodNet program. Guest, who previously worked on FoodNet operations, explained that the program previously collected patient data, tested food samples from state labs, and collated information at a national level to speed outbreak investigations. “When we see an outbreak or a cluster or something, we don’t have the data we normally expect to go back to use to help us, and this is one of those consequences,” she said. “You’re starting in the dark.”
HHS officials have pushed back on criticism, telling the BBC that the CDC continues to collaborate with more than 3,000 local and state health departments to collect cyclospora data through alternative surveillance systems, and that overall health funding for foodborne illness work has “remained stable”. However, state health departments across the country report feeling the impact of reduced federal support. In Colorado, which has recorded 90 cases this year in line with typical annual totals, the state health department confirmed it has received less federal funding and operates with fewer staff assigned to case monitoring. “While our colleagues at the CDC are working hard to support state partners, we have had to adapt to federal changes,” said Hope Shuler, a spokesperson for Colorado’s public health department. The state has continued all core testing, monitoring and data reporting to the CDC despite the cuts, she added.
Not all experts agree that the post-cut system is failing: Manderach noted that federal food safety agencies have largely maintained previous performance standards despite restructuring that began during the Trump administration, adding that “while yes, I do think there were challenges early on, most of those seem to have resolved.”
Other public health leaders point to competing priorities that have stretched federal resources thin, including the ongoing deadly Ebola outbreak in the Democratic Republic of the Congo that has demanded significant attention and funding. This resource strain has shifted more responsibility for foodborne illness outbreak investigations to state governments, explained Nancy Glick of the National Consumers League. “States are doing that now, but they don’t have the resources that the CDC had,” she said.
Currently, the core investigative work relies on time-consuming interviews with every person who tests positive for cyclospora, asking them to recount every food they consumed in the two weeks before they developed symptoms. Investigators hope to identify a common contaminated product or exposure point that can be pulled from the market to end the outbreak. But experts note that this work requires extensive staffing, a resource many small local health departments simply do not have available. “It is pretty straightforward, but it takes a lot of person power to do it,” said David Weber, a professor of medicine, pediatrics and epidemiology at University of North Carolina at Chapel Hill.
For American consumers, the ongoing uncertainty has left them to rely on general prevention measures to avoid the uncomfortable illness. “At the moment, the list of things that you need to be concerned about is unfortunately quite long, making it feel really hard to control,” Guest said.