When Michigan resident Nick Palmiter developed stomach problems in early July, he initially expected them to pass. Instead, the pain intensified until he was reportedly using the bathroom between 15 and 20 times a day.
A visit to urgent care led to an emergency-room referral and a diagnosis of cyclosporiasis, an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. His experience, described in a BBC report on the outbreak, reflects the disruption being experienced by thousands of Americans during an unusually large surge in infections.
The US Centers for Disease Control and Prevention had received reports of 4,173 laboratory-confirmed domestically acquired cases between May 1 and July 20, 2026. At least 308 patients had been hospitalised, and confirmed infections had been reported across 41 states. No deaths had been recorded. The agency was also reviewing more than 7,400 additional cases that had not yet been laboratory confirmed, many of them reported by Michigan and Ohio.
One Outbreak Is Only Part of a Much Larger Surge
The national total does not represent one single contaminated meal or restaurant chain.
Public-health agencies are investigating several clusters and outbreaks occurring during the same period. The largest clearly identified cluster involves iceberg lettuce and has affected nine states: Illinois, Indiana, Kansas, Kentucky, Michigan, Ohio, Oklahoma, Pennsylvania and West Virginia.
As of July 20, officials had connected 1,947 illnesses and 98 hospitalisations to that outbreak. Many patients reported eating food containing shredded iceberg lettuce at Taco Bell locations before becoming sick. The illness-onset dates continued through July 20, suggesting that additional cases could still be reported because confirming and connecting an infection to an outbreak can take several weeks.
The remaining nationally reported illnesses may involve unrelated food sources, independent clusters or cases that investigators have not yet connected. The FDA is also examining another group of at least 72 infections for which no specific product or location has been publicly identified.
This distinction explains why different reports contain very different numbers. The nationwide surveillance total is larger than the number currently linked to the nine-state lettuce outbreak.
What Cyclospora Does to the Body
Cyclospora is a single-celled parasite that infects the small intestine. People generally become ill after consuming food or water contaminated with human faeces containing the parasite.
Symptoms usually begin approximately one week after exposure, although the incubation period can range from two days to two weeks or longer. The delay makes identifying a source difficult because patients must remember everything they ate during an extended period before becoming sick.
Watery diarrhoea is the defining symptom and can become frequent or explosive. Patients may also experience severe cramping, bloating, nausea, increased gas, loss of appetite, weight loss and exhaustion. Less common symptoms include vomiting, headaches, body aches and a low-grade fever.
For someone visiting the bathroom 20 times a day, the effects extend far beyond physical discomfort. Normal work becomes difficult, sleep is repeatedly interrupted and leaving the house may feel impossible. The rapid loss of fluids can also lead to dehydration, dizziness and weakness.
The illness may appear to improve before returning. Without treatment, symptoms can persist for more than a month and may relapse several times. Fatigue can continue even after the diarrhoea has stopped.
Cyclospora Does Not Spread Like an Ordinary Stomach Bug
The parasite is transmitted through faecal contamination, but direct person-to-person spread is considered unlikely.
After Cyclospora leaves an infected person’s body, it must remain in the environment for at least one to two weeks before becoming infectious. A person is therefore unlikely to immediately transmit it to family members in the manner associated with norovirus.
Contamination is more likely to happen when human waste reaches irrigation water, washing water or food-handling environments. Fresh produce can then carry the parasite through processing, transportation, restaurants and shops.
Cyclospora is believed to infect humans rather than animals, making human waste the central source of contamination. Previous US outbreaks have been associated with foods including lettuce, basil, cilantro, raspberries, snow peas and packaged salad mixes.
Why Investigators Are Focused on Iceberg Lettuce
The FDA’s traceback work identified Taylor Farms de Mexico as the common supplier of shredded iceberg lettuce served at Taco Bell restaurants visited by many patients.
Taylor Farms subsequently removed iceberg lettuce sourced from central Mexico from the US market. The recall covered products distributed between June 29 and July 16 to retail, restaurant and food-service customers across at least 27 states. Some affected products were sold under Marketside and several food-service labels. The complete product information appears in the FDA recall notice.
The investigation became confusing after an FDA laboratory result initially appeared to detect Cyclospora in a lettuce sample collected at the border. Further examination found that the result was a false positive.
That correction did not end the recall or eliminate lettuce as the suspected source. The FDA says epidemiological interviews and supply-chain tracing continue to converge on shredded iceberg lettuce supplied by Taylor Farms from growers in central Mexico, even though no product sample had produced a confirmed positive result as of July 19.
Foodborne-outbreak investigations do not always require a positive sample. Contaminated products may have been eaten or discarded before testing begins, while parasites may be distributed unevenly across a shipment.
Washing Produce May Not Remove the Parasite
Thoroughly rinsing produce remains good food-safety practice, but it cannot guarantee that Cyclospora will be removed.
The parasite can adhere to the surfaces and folds of fruits and vegetables. Routine chemical sanitisers may also be ineffective against it, creating a challenge for farms, processing facilities, restaurants and households.
The CDC recommends washing hands and rinsing fresh produce thoroughly under running water. Outer leaves should be removed where appropriate, while cut or peeled produce should be refrigerated promptly.
Cooking is more reliable. Heating produce to at least 158°F, or 70°C, kills the parasite. That option is practical for many vegetables but does not solve the problem for foods normally consumed raw, such as salads and fresh herbs.
Consumers should check the exact recall notice rather than avoiding every vegetable indefinitely. The nine-state investigation involves identified iceberg-lettuce products, while officials continue examining other clusters that may have different sources.
Diagnosis Can Be Surprisingly Difficult
Cyclosporiasis cannot always be identified through a standard stool test.
Laboratories may need to use specialised microscopic or molecular testing, and healthcare providers may have to request Cyclospora specifically. The parasite can also be shed intermittently and in low concentrations, meaning several samples collected on different days may be necessary.
This creates a risk that patients will initially be told they have an unidentified stomach infection or ordinary food poisoning. The delayed diagnosis allows symptoms to continue and makes it harder for health departments to establish connections between cases.
The CDC advises people experiencing prolonged watery diarrhoea, loss of appetite or unusual fatigue to contact a healthcare provider and mention cyclosporiasis, particularly when symptoms continue for more than a few days.
Severe warning signs include an inability to keep liquids down, diarrhoea lasting longer than three days, reduced urination, a dry mouth or dizziness when standing. These symptoms can indicate significant dehydration and require medical attention.
Treatment Can End Weeks of Illness
The recommended treatment is the prescription antibiotic combination trimethoprim-sulfamethoxazole, commonly sold as Bactrim, Septra or co-trimoxazole.
CDC guidance recommends a seven-to-10-day course for confirmed infections in most otherwise healthy adults and children older than two months. People with weakened immune systems may require longer treatment. Medication choice and dosage must be determined by a healthcare professional.
People with sulfa allergies should discuss alternatives with their clinician. The CDC notes that no other highly effective treatment has been firmly established, making professional assessment particularly important for those unable to take the standard medication.
Rest and fluid replacement are also essential. Someone losing water through repeated diarrhoea may need oral rehydration solutions rather than relying only on ordinary water, especially when symptoms are severe.
The Human Toll Is Larger Than the Confirmed Count
The official number almost certainly understates how many people have become ill.
Some patients recover without visiting a doctor. Others may not receive the specialised test required to detect Cyclospora, while recent illnesses may not yet have reached federal surveillance systems. The CDC explicitly says the true number of cases is probably higher than the reported figure.
Behind each number is an experience resembling Palmiter’s: repeated bathroom visits, severe abdominal pain, missed work and uncertainty about what caused the illness.
The recalled lettuce is being removed from distribution, but the investigation remains active. More cases may emerge because of the long incubation period, reporting delays and separate outbreaks whose sources have not yet been identified.
For most healthy people, cyclosporiasis is not fatal. That does not make it trivial. An illness that sends someone to the bathroom 20 times a day, disappears and then returns for weeks can dominate every part of daily life.
