Cyclospora Cases Climb, But Actual Number Unclear as CDC Reporting Lags Behind States
CDC cut the parasite from its national FoodNet Surveillance program one year ago.
Editor's note: This story has been edited to include the latest outbreak updates, listed chronologically at the bottom of the article. Alternatively, you can read the most recent coverage here.
The cyclosporiasis outbreak sweeping the U.S. continues to grow. As of July 9, the U.S. Centers for Disease Control and Prevention (CDC) reports 843 confirmed cases of domestically acquired foodborne Cyclospora infection in 31 states, plus more than 1,500 cases pending analysis and 343 cases acquired during international travel.
Meanwhile, the Michigan Department of Health and Human Services (MDOH) has alone reported 2,640 cyclosporiasis cases as of July 13.
New York State officials have also reported 470 cases, and Ohio reported 177.
The majority of cyclosporiasis cases reported by CDC and state public health officials have occurred after May or June 2026.
Michigan Looks at Lettuce as Possible Source
A food vehicle (or vehicles) of illness have not yet been definitively identified, but Michigan officials said that early information has revealed lettuce as a common product of interest in the investigation.
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.
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At present, FDA has added just two Cyclospora outbreak investigations (one with eight 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.
Update, July 14, 2026: The article has been edited to include the most recent case count from MDOH.
Update, July 15, 2026: CDC has issued a health advisory warning the public of the increase in domestically acquired cyclosporiasis cases reported across the U.S., including a large outbreak cluster in the Midwest. Since May 1, 2026, CDC has received reports of 1,645 laboratory-confirmed domestically acquired Cyclospora cayetenensis infections spanning 34 states, with more than 5,100 additional cases requiring analysis. At least 400 cases in Michigan, Ohio, West Virginia, and Kentucky appear to be epidemiologically linked.
As of July 14, MDOH has reported more than 3,300 cases in the state alone. Read more.
Update, July 16, 2026: As of today, MDOH reports 4,312 cases resulting in 102 hospitalizations.
Update, July 17, 2026: FDA announced an outbreak cluster including 1,644 people across Indiana, Kentucky, Michigan, Ohio, and West Virginia. Shredded iceberg lettuce served at Taco Bell locations and sourced from a single Mexican supplier has been identified as the vehicle of infection. Read more.
Update, July 20, 2026: Taylor Farms of Mexico has been officially named as the supplier of implicated iceberg lettuce products to firms like Taco Bell and Walmart. Michigan is now reporting more than 5,000 cyclosporiasis infections in the state since June. Read more.
Update, July 21, 2026: As of July 20, Michigan reports 6,571 cyclosporiasis infections and Northwest Ohio has seen 2,029 cases. Read more.
Update, July 23, 2026: CDC has reported 4,173 laboratory-confirmed, domestic cases of cyclosporiasis connected to the five-state outbreak, with an additional 7,400 cases under investigation. Michigan is now reporting 7,171 cases.
FDA has added a new Cyclospora outbreak of 72 cases to its CORE Investigation table.
Several senators have written letters to U.S. Health Secretary Kennedy urging Cyclospora surveillance to be restored to the FoodNet program. Experts say that FoodNet cuts, although problematic, did not cause the current outbreak. Read more.
Update, July 24, 2026: The outbreak linked to Taylor Farms iceberg lettuce has been expanded to nine states. More than 1,900 people infected with Cyclospora have reported exposure to Taco Bell, and there have been at least 98 hospitalizations. Michigan and Northwestern Ohio report 7,664 and 2,380 cases, respectively.FDA is currently investigating three other cyclosporiasis outbreaks aside from the nine-state cluster, comprising eight, ten, 18, and 72 cases. A food vehicle of infection has not yet been identified in any of these outbreaks. Read more.
Update, August 5, 2026: CDC has updated its total laboratory-confirmed case count of cyclosporiasis in the U.S. to 10,468 illnesses and 517 hospitalizations, as of August 3. CDC has also updated the number of states reporting cases to 47. The agency noted on August 4 that an additional 12,255 cases require further analysis and have not yet been laboratory confirmed or determined to be part of the U.S. domestic outbreak.
Additionally, CDC has expanded its list of states specifically associated with the Taylor Farms iceberg lettuce outbreak to 15, up from nine, and is reporting 6,358 illnesses, 278 hospitalizations, and two deaths associated with this outbreak. Affected states now include Arkansas, Iowa, Nebraska, New Hampshire, North Carolina, Missouri, Illinois, Indiana, Kansas, Kentucky, Michigan, Ohio, Oklahoma, Pennsylvania, and West Virginia.
Update, August 12, 2026: CDC has updated its total laboratory-confirmed case count of cyclosporiasis in the U.S. to 13,895 illnesses, 740 hospitalizations, and two deaths in 47 states. CDC is aware of at least 10,455 additional cases of cyclosporiasis that are not laboratory-confirmed or require further investigation to determine whether they were somestically acquired. Many of the additional cases continue to be reported by Michigan, which, as of August 6, reports 12,485 cases and 279 hospitalizations.
Update, August 13, 2026: According to FDA, the number of cyclosporiasis cases linked to Taylor Farms lettuce is 9,481 in 17 states. Since the last update, two additional states have been added: Maine and Massachusetts.
FDA has also initiated an onsite inspection and sampling at Taylor Farms of Mexico in coordination with Mexican officials. The agency says it "remains confident that all recalled iceberg lettuce related to this specific Cyclospora outbreak is off the market."Update, August 20, 2026: Since May 1, 2026, CDC has received reports of 15,716 laboratory-confirmed cases of cyclosporiasis acquired in the United States. For comparison, 1,180 cases were reported in the United States between May 1 and August 31, 2025. At least 11,841 additional cases of cyclosporiasis may require further investigation and analysis. The Taylor Farms lettuce outbreak has contributed significantly to the increase of Cyclospora cases in 2026, but CDC has not updated its official outbreak-specific case count since August 13.
Update, August 21, 2026: The total case count associated with the multistate lettuce outbreak is now 10,930 illnesses reported from 17 states.
