Surge in Cyclosporiasis Cases: Nearly 7,000 Suspected Across US, Linked to Foodborne Parasite

The Centers for Disease Control and Prevention (CDC) has issued a health alert warning of a significant increase in cases of cyclosporiasis, a parasitic infection causing severe, often explosive watery diarrhea. Since May 1, 2026, the agency has confirmed 1,645 domestically acquired cases, with more than 5,100 additional cases under investigation, bringing the potential total to nearly 7,000.

This marks a dramatic rise compared to the same period last year, when only about 249 confirmed cases were reported nationally. Cases have been identified in at least 34 states, with no reported deaths but 141 hospitalizations (about 9% of confirmed cases).

Cyclosporiasis is caused by the microscopic parasite Cyclospora cayetanensis. Infection occurs through consuming food or water contaminated with the parasite, often via human feces. It is not typically spread person-to-person.

Symptoms usually appear about one week after exposure ranging from 2–14 days and can include:
• Watery diarrhea (frequent and sometimes explosive)

• Loss of appetite and weight loss

• Bloating, cramping, increased gas, and nausea

• Fatigue

• Less commonly: low-grade fever or vomiting

Without treatment, symptoms can relapse and persist for days to a month or longer.

The illness is treatable with the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX, or Bactrim) for most people.

Michigan has been hit hardest, reporting over 3,300 confirmed cases. A multistate cluster involving more than 400 cases links Michigan, Ohio, West Virginia, and Kentucky, with symptom onset after June 22.

Health officials suspect contaminated fresh produce, particularly lettuce or salad greens, as a likely source, though no specific product, supplier, or restaurant chain has been definitively confirmed. Investigations by the CDC, FDA, and state agencies are ongoing, including potential links to items like those used in salads.

Taco Bell has voluntarily removed some ingredients as a precaution at certain locations, but no confirmed connection exists.

Cyclosporiasis cases typically peak in spring and summer due to seasonal produce consumption.

This year’s surge is unusually high, and experts note that underdiagnosis and recent changes in federal surveillance making reporting optional in some systems may mean actual numbers are even higher.

The CDC and health officials recommend:

• Thoroughly wash fresh produce under running water before eating, even if labeled “pre-washed.” Scrubbing or peeling where possible can help, though the parasite is hardy.

• Cook produce if feasible, as heat kills the parasite.

• Seek medical care for prolonged watery diarrhea, especially if accompanied by the symptoms above. Request specific Cyclospora testing, as routine stool tests may miss it.

• Stay hydrated and consult a doctor for treatment if needed.

Public health experts emphasize that while the outbreak is serious, it is rarely life-threatening for otherwise healthy individuals.

More cases are expected through August as investigations continue.