Federal and state health officials confirmed on July 23, 2026, that the Cyclospora outbreak sweeping across Michigan and much of the United States has now become the worst recorded parasitic foodborne illness event in the country's documented history. The Michigan Department of Health and Human Services reported 7,664 total cases as of 9:30 a.m. that morning, up from 7,171 the previous day. Of those, 160 people have been hospitalized.
At the national level, the CDC confirmed 4,173 laboratory-verified domestically acquired cases across 41 states as of July 21, with 308 hospitalizations and no deaths. An additional 7,400 cases are under investigation to determine whether they were also domestically acquired. No deaths have been reported.
Why This Matters
Cyclosporiasis, the illness caused by the Cyclospora cayetanensis parasite, is not the kind of foodborne illness that passes quickly. Without antibiotic treatment, it can last from a few days to more than a month. The parasite causes watery, often explosive diarrhea, along with loss of appetite, weight loss, abdominal cramping, bloating, nausea, and fatigue. It is particularly dangerous for older adults, pregnant people, and anyone with a weakened immune system.
The scale of this outbreak is what makes it unlike anything seen before. Michigan typically sees around 50 cases of cyclosporiasis per year, according to MDHHS. The state has now reported more than 7,600 cases in a single season. For perspective, the prior 2025 national total for the same period was 249 cases. This outbreak has already exceeded that 17-fold at the federal level alone.
The outbreak is also occurring during peak Cyclospora season, which the CDC defines as May 1 through August 31. Officials say case counts are expected to continue rising through the end of August.
What We Know So Far
CDC and FDA investigators have directly linked a multistate cluster of at least 1,644 cases to shredded iceberg lettuce served at Taco Bell locations in five states: Indiana, Kentucky, Michigan, Ohio, and West Virginia. Traceback identified a single supplier, Taylor Farms de Mexico, which on July 17, 2026, voluntarily recalled all iceberg lettuce sourced from central Mexico, including Marketside-brand products sold at Walmart under the labels "Iceberg Salad" and "Shredded Lettuce" with best-by dates through August 3, 2026.
90% of those interviewed by Michigan MDHHS investigators who reported eating at Taco Bell said they had eaten iceberg lettuce. The FDA is continuing to determine whether the contaminated lettuce reached other restaurant chains and retail locations beyond the five named states. The CDC has separately clarified that the national outbreak involves multiple clusters, not all of which are linked to the Taco Bell/Taylor Farms source.
The FDA also added a new, separate Cyclospora outbreak to its investigation table on July 23, involving 72 cases with an unidentified source, distinct from the Taco Bell cluster. That investigation is in its early stages.
Where the Risk Is Highest
Michigan is the epicenter of this outbreak. MDHHS data shows the outbreak was first identified on June 29, when Monroe County reported a cluster. Cases have since spread to counties across the state, with adults aged 30 to 39 accounting for the highest share. The five-state cluster involving Indiana, Kentucky, Michigan, Ohio, and West Virginia is the most clearly defined geographic concentration, but cases have been reported in 41 states, meaning no major U.S. metro is fully insulated.
Among the states with the highest case burdens beyond Michigan, according to CDC surveillance data, Ohio, Indiana, New York, North Carolina, Texas, Illinois, Kentucky, and Virginia have reported notable concentrations. New York City has also seen elevated case counts. The Association of State and Territorial Health Officials has noted that molecular tracking of Cyclospora is significantly harder than for bacterial pathogens, because whole genome sequencing is not available for this parasite, forcing investigators to rely on epidemiological data such as restaurant receipts and supply chain records.
What Doctors and Experts Say
"Anyone experiencing gastrointestinal illness, such as sudden and ongoing diarrhea, should contact their health care provider and their local health department," MDHHS said in a public statement.
Gwen Biggerstaff, deputy director of the CDC's Division of Foodborne, Waterborne, and Environmental Diseases, acknowledged the difficulty of the investigation. "Cyclospora investigations take a significant amount of time," Biggerstaff said earlier this month, explaining that the parasite is difficult to detect in food, that whole genome sequencing is unavailable for this organism, and that weeks can pass between exposure and diagnosis, by which point the food source may no longer be available for testing.
Several U.S. senators have written letters to Health Secretary Robert F. Kennedy Jr. urging the restoration of Cyclospora surveillance to the FoodNet program. Experts have stated that cuts to FoodNet, while concerning for long-term surveillance capacity, did not cause this specific outbreak.
What the Evidence Shows and What It Does Not
The epidemiological link between Cyclospora cases in the five-state cluster and shredded iceberg lettuce served at Taco Bell is based on thorough investigative analysis, including ingredient-level food exposure interviews conducted on 190 Michigan cases. However, the FDA announced this week that a positive laboratory sample from Taylor Farms lettuce that was initially reported has now been determined to be a false positive, and the investigation into the specific mechanism of contamination is ongoing.
The parasite itself is well understood. Cyclospora cayetanensis is a unicellular organism found in contaminated water or food, typically raw produce. It cannot be killed by standard disinfectants and is not reliably detected in routine stool tests unless the clinician specifically orders Cyclospora testing. The CDC has urged clinicians to order specific Cyclospora stool analysis, including PCR-based molecular testing where available, for any patient presenting with prolonged watery diarrhea.
Who Faces the Greatest Risk
Cyclospora can sicken people of any age, and cases in this outbreak have ranged from 2 to 95 years old. However, people with weakened immune systems, including those undergoing cancer treatment, transplant recipients, people with HIV, pregnant individuals, and older adults, are most likely to experience severe or prolonged illness. The illness is not known to spread person-to-person.
Anyone who has eaten shredded iceberg lettuce at a Taco Bell in Indiana, Kentucky, Michigan, Ohio, or West Virginia since mid-May, or who has consumed Taylor Farms de Mexico iceberg lettuce products sold at Walmart with best-by dates through August 3, 2026, should monitor for symptoms.
Symptoms and Warning Signs to Watch For
Symptoms of cyclosporiasis typically begin about one week after exposure, though the range is two to 14 days. Key symptoms include frequent watery diarrhea, which can be profuse, as well as loss of appetite, weight loss, abdominal cramps, bloating, nausea, low-grade fever, and fatigue. Vomiting is less common. Without treatment, symptoms can persist for weeks or recur over months.
The illness can be treated effectively with the antibiotic trimethoprim-sulfamethoxazole, commonly sold as Bactrim, Septra, or Cotrim, taken orally for 10 days according to CDC treatment guidelines. People experiencing prolonged or worsening symptoms, dehydration, or severe weakness should seek medical care promptly.
What You Can Do Now
Discard any iceberg lettuce from Taylor Farms de Mexico purchased at Walmart with best-by dates between July 18 and August 3, 2026. Do not eat shredded iceberg lettuce from Taco Bell locations in Indiana, Kentucky, Michigan, Ohio, or West Virginia. If you are unsure of the source of the lettuce you are buying or ordering, ask the supplier or restaurant.
When preparing whole-head lettuce at home, discard the outer two to three layers of leaves and wash inner leaves thoroughly under clean running water. Pre-washed bagged lettuce should not be assumed safe; rewashing is recommended, though the CDC notes it may not fully eliminate the parasite. Peeling and cooking produce when possible provides additional protection.
Anyone in Michigan or the five-state outbreak zone who has been experiencing unexplained diarrhea lasting more than a few days should contact a health care provider and specifically request Cyclospora stool testing, as routine lab panels do not routinely include it.
Cost and Access: What Patients Should Know
The antibiotic used to treat cyclosporiasis is a generic medication widely covered by insurance and available at low cost without insurance at most pharmacies. Testing requires a stool sample sent to a laboratory with specific instructions for Cyclospora detection. Patients without a primary care provider can contact their local county or state health department for guidance on testing options and care. Most community health centers accept Medicaid and offer sliding-scale fees.
What Happens Next
The CDC expects case counts to continue rising through August, when the typical Cyclospora season ends. The FDA's separate investigation into the 72-case outbreak with an unidentified source is in early stages, and additional outbreaks may be added to the investigation table. MDHHS is updating its case count daily, Monday through Friday, by 11:00 a.m. Eastern Time. MedicalDaily will update this story as federal and state data are revised.
The Bottom Line
The 2026 Cyclospora outbreak is the largest parasitic foodborne illness event on record in the United States, and it is not over. The most actionable step for readers in the affected region is to follow the iceberg lettuce advisory, request specific Cyclospora testing from a clinician if experiencing prolonged diarrhea, and stay updated through the CDC and MDHHS outbreak pages as case counts evolve daily.
