The majority of cyclosporiasis cases reported by CDC and state public health officials have occurred after May or June 2026.

A food vehicle (or vehicles) of illness have not yet been definitively identified, but previous reports based on emails between CDC and other public health agencies revealed that CDC has been investigating clusters linked to Mexican-style restaurants, a grocery chain, and a catered event. FDA’s Coordinated Outbreak Response and Evaluation (CORE) network is also conducting traceback investigations on white and green onions, cucumbers, and cilantro to narrow down the list of potential transmission vehicles. Cyclospora cayetanensis is typically associated with fresh produce items.

At present, FDA has added just two Cyclospora outbreak investigations (one with seven cases and one with 18 cases) to its CORE table. Neither has been linked to a food source yet.

Cyclospora: A Challenging Parasite That is Growing in Prevalence 

Since the 1990s, the prevalence of C. cayetanensis has had an upward trajectory, trending toward possible endemicity. As explained by expert Larry Keener, CFS, PA in Food Safety Magazine, 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. Between 2019 and 2022, the number of laboratory-confirmed cases of cyclosporiasis in the U.S. ranged from a high in 2019 of 2,408 cases to a low in 2021 of 1,024 cases. By 2023, there were nearly 3,000 cases of cyclosporiasis reported in the U.S.

Parasites like C. cayetanensis are challenging to isolate and identify, as they are not culturable like bacteria and viruses, and infections typically require direct microscopic evidence from stool samples to diagnose. These conditions increase the likelihood of failure in identification and contribute to inefficient traceback efforts. Exemplifying the challenge posed by the parasite to public health officials, of the four foodborne illness outbreaks attributed to C. cayetanensis in 2023, three were inconclusive in determining a food source. Similar trends and investigation outcomes were seen in 2022 and 2024.

Cyclosporiasis is now considered an "important neglected parasitic infection" by CDC. It is also a nationally notifiable disease.

Cyclospora Eliminated from CDC Foodborne Pathogen Surveillance Program in 2025

Although cyclosporiasis is a nationally notifiable disease, CDC surveillance of the foodborne parasite took a big hit last year when the agency cut the number of pathogens monitored under the Foodborne Diseases Active Surveillance Network (FoodNet) from eight to two. C. cayetanensis was one of the pathogens cut from this program.

FoodNet is a joint effort among CDC, the U.S. Food and Drug Administration (FDA), the U.S. Department of Agriculture (USDA), and ten state health departments. Although state health departments are no longer required to surveil for the six pathogens cut from FoodNet, they can continue to conduct surveillance for those pathogens on their own, if they so choose.

At the time the cuts were revealed, food safety and public health experts warned that the decision may compromise the ability to recognize when cases of illness related to a certain pathogen begin to rise, hindering foodborne illness outbreak response, and that accurate analysis of trends over time could also be impacted.