Cyclospora Outbreak: What to Know
Lilian White, MD
July 27, 2026
A Cyclospora outbreak has recently been detected in at least 34 states. Cyclospora cayetanensis is a single-celled parasite that causes gastrointestinal illness and is among the nationally notifiable parasitic infections. More than 800 infections have been reported nationwide since May 2026, although this is likely an undercount because it excludes probable cases or cases in patients who do not seek medical care. According to the US Food and Drug Administration, the source of the current outbreak has been linked to iceberg lettuce served at some Taco Bell locations, but infections are typically associated with water, food, or soil sources. Approximately 10% of patients with reported infections have been hospitalized.
Cyclospora infection occurs more commonly during the spring and summer. Person-to-person transmission is unlikely because it takes 2 weeks for oocytes to become sporozoites, which are capable of causing infection. Humans are the only host. Symptoms range from none to mild watery diarrhea to severe enteritis and can occur after an incubation period of about 7 days. Cyclospora infection may also cause extraintestinal symptoms in patients who are immunocompromised, such as inflammatory arthritis, acalculous cholecystitis, Guillain-Barré syndrome, urethritis, and ocular inflammation. Imaging may demonstrate gallbladder wall thickening and biliary duct dilatation.
Diagnosis of Cyclospora infection is made by detecting oocytes in stool. Specific staining is required and must be requested at the time of ordering a stool ova and parasite test. Oocytes are not shed frequently in the stool, and multiple stool samples are recommended a few days apart. Stool polymerase chain reaction testing is 95% sensitive and specific but may be less cost-effective.
Supportive care and hydration are foundational for treatment of Cyclospora infections. Although most healthy people will recover fully without antibiotics, treatment reduces the disease course, which may otherwise persist for weeks to months. Trimethoprim/sulfamethoxazole is the first-line treatment. For healthy adults, the dose is 160 mg/800 mg two times per day for 7 to 10 days. For healthy children ≥ 2 months of age or older, the dose is 8 to 10 mg/kg trimethoprim and 40 to 50 mg/kg sulfamethoxazole per day, orally, in two divided doses for 7 to 10 days. Trimethoprim/sulfamethoxazole is considered safe for use in patients who are breastfeeding unless the infant has jaundice or glucose-6-phosphate dehydrogenase deficiency, is premature, or is ill. A test of cure is not recommended if diarrhea has resolved.
The Wilderness Medical Society recommends heating water and food to between 140oF and 158oF (60oC to 70oC) for 30 minutes to kill enteric pathogens such as Ccayetanensis . Flash pasteurization at 158oF to 162oF (70oC to 72.2oC) is effective in only 30 seconds. Chemical disinfection does not prevent transmission of Cyclospora.