Recognizing the symptoms of cyclospora has become urgent for American families this summer, as the parasite continues spreading through a nationwide foodborne outbreak. Federal health officials say the illness has now touched dozens of states, and the case count keeps climbing even as one major outbreak shows signs of slowing.
Cyclosporiasis is the gastrointestinal illness caused by the microscopic parasite Cyclospora cayetanensis. People become infected after eating food or drinking water contaminated with the parasite, and this summer’s surge has been tied largely to iceberg lettuce.
The Current Outbreak Picture
The Centers for Disease Control and Prevention reported at least 15,716 laboratory-confirmed cases of domestically acquired cyclosporiasis since May 1, 2026. That number reflects only confirmed infections. Officials believe the real total is higher, since many people recover without ever being tested.
A large piece of this surge traces back to a single source. Investigators linked a 15- to 17-state outbreak to iceberg lettuce processed by Taylor Farms de Mexico. At least 6,707 of the domestically acquired cases fall under this specific investigation, according to Washington State health officials tracking the outbreak.
Some of the sickened individuals ate the contaminated lettuce at Taco Bell locations across nine states, including Indiana, Kentucky, Michigan, Ohio, and Pennsylvania. Taylor Farms initiated a voluntary recall of all iceberg lettuce sourced from central Mexico on July 17, 2026.
The recalled lettuce carried best-by dates that have since passed. CDC confirms the product should no longer be available in stores or restaurants. Even so, new cases tied to this outbreak continued to appear through mid-August, since illness onset can take weeks to connect to a food source.
Michigan has been hit hardest overall. State health officials there reported 14,277 cyclosporiasis cases so far in 2026, and two deaths involving people with severe underlying health conditions. Cases in Michigan have slowed considerably since early August, prompting the state health department to reverse its earlier recommendation to avoid bagged salad greens.
How Cyclospora Spreads
Cyclospora spreads through a fecal-oral route. An infected person sheds parasite oocysts in their stool, and those oocysts must sit in the environment for one to two weeks before they become infectious to someone else. This delayed maturation is part of why the parasite is not usually passed directly from person to person.
Contaminated fresh produce has driven nearly every major U.S. outbreak. Past incidents involved bagged salad mixes, fresh cilantro, fresh basil, raspberries, snow peas, and green onions. This year’s dominant driver has been imported iceberg lettuce.
CDC treats May 1 through August 31 as the official cyclosporiasis season, since case counts typically climb during spring and summer months. Experts still are not entirely certain why the parasite behaves this way, though warmer growing conditions in source regions likely play a role.
Recognizing the Symptoms of Cyclospora
The most common and defining symptom of cyclospora infection is watery diarrhea, which can become frequent and, in some cases, explosive. Beyond diarrhea, infected individuals commonly report several other complaints.
Typical symptoms include:
- Watery, frequent diarrhea
- Loss of appetite
- Unintended weight loss
- Bloating and gas
- Nausea
- Fatigue
Less common but still reported symptoms include low-grade fever and vomiting. Some patients also experience abdominal cramping and muscle aches. Notably, not everyone infected with Cyclospora develops symptoms at all, which makes tracking true infection rates difficult for health departments.
Symptoms typically begin about one week after exposure, though the incubation period can range anywhere from two days to two weeks or longer. This wide window is one reason investigators have struggled to pin illnesses to a single meal or location.
Left untreated, cyclosporiasis can persist anywhere from a few days to a month or more. The illness often follows what doctors describe as a remitting-relapsing pattern, meaning symptoms can appear to improve before returning one or more times.
Who Faces the Greatest Risk
Anyone can contract Cyclospora, and prior infection does not provide lasting immunity. People can become reinfected more than once, even after successfully treating a previous case.
Immunocompromised individuals face a higher risk of severe or prolonged illness. Health officials urge anyone in this group who suspects infection to contact a physician quickly for testing and treatment.
Recent CDC surveillance data on domestically acquired cases showed patients ranging in age from 2 to 95 years old, with a median age of 44. Slightly more than half of confirmed cases involved women. Roughly 9% of case-patients required hospitalization, and outbreak-wide, health officials have confirmed at least 454 hospitalizations tied specifically to the lettuce-linked investigation.
Getting Diagnosed and Treated
Diagnosing cyclosporiasis is not always straightforward. Standard stool exams often fail to detect the parasite, even in people showing clear symptoms. Physicians typically need to request a specific test for Cyclospora rather than relying on a routine ova-and-parasite panel.
Because shedding levels can vary day to day, some patients need to submit multiple stool samples collected on separate days before doctors can confirm an infection. Anyone experiencing persistent watery diarrhea, especially lasting longer than a few days, should ask a healthcare provider specifically about Cyclospora testing.
Once diagnosed, treatment usually involves the antibiotic trimethoprim-sulfamethoxazole, sold under brand names including Bactrim and Septra. Patients allergic to sulfa drugs should discuss alternative approaches with their doctor, since no clearly effective substitute has been established. Staying well hydrated remains important throughout recovery, and some patients benefit from antidiarrheal medication alongside antibiotic treatment.
While cyclosporiasis is rarely life-threatening, it can lead to complications in some cases. Reported complications include malabsorption, cholecystitis, and reactive arthritis, underscoring why prompt diagnosis matters even for a generally self-limiting illness.
What Health Officials Recommend Now
The FDA continues urging consumers to avoid any recalled Taylor Farms de Mexico iceberg lettuce, including servings at restaurants. Diners are encouraged to ask restaurant staff about the source of iceberg lettuce before ordering, particularly in states previously tied to the outbreak.
CDC and FDA are also tracking at least six additional Cyclospora clusters nationwide that remain unrelated to the lettuce investigation. Sources for these separate clusters have not yet been confirmed, and officials say they will issue new outbreak notices if a public health action becomes necessary.
Basic food safety habits remain the strongest defense against infection. Washing fruits and vegetables thoroughly before eating them helps reduce risk, and cooking produce when possible can kill the parasite outright. Travelers heading to tropical or subtropical regions where cyclosporiasis is endemic should take extra care with food and water sources, since routine chemical disinfection does not reliably kill Cyclospora.
Anyone diagnosed with cyclosporiasis may be contacted by local or state health officials asking about meals eaten in the two weeks before symptoms began. Answering these calls, health departments say, plays a direct role in helping investigators trace outbreaks back to their source.
Have you or someone you know experienced these symptoms this summer? Share your story in the comments below.