Federal health officials are investigating a growing outbreak of cyclosporiasis, an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. The Centers for Disease Control and Prevention, working with the Food and Drug Administration and state health departments, has tied one multistate cluster to a specific food source — and is separately tracking a much larger nationwide rise in cases this summer.
The parasite spreads when people consume food or water contaminated with feces containing it, and fresh produce has been a repeat culprit in past U.S. outbreaks. This year, the pattern has returned at scale.
The lettuce outbreak the CDC has pinned down
The CDC's most specific finding concerns shredded iceberg lettuce served at some Taco Bell locations. Epidemiologic and traceback data, the agency says, show that lettuce contaminated with Cyclospora made people sick across five states — Indiana, Kentucky, Michigan, Ohio and West Virginia. As of the CDC's update, 1,644 people who reported eating at Taco Bell had been infected, with 94 hospitalizations and no deaths. Illnesses began on dates ranging from mid-May to mid-July.
The FDA's traceback pointed to a single supplier of shredded iceberg lettuce from Mexico, and Taco Bell has said it will stop using lettuce from that supplier; a recall of iceberg lettuce grown in central Mexico followed. Investigators are still working to determine whether any potentially contaminated lettuce remains on the market. The CDC's guidance is direct: do not eat shredded iceberg lettuce from Taco Bell locations in those five states.
A bigger national picture
Beyond that identified cluster, the CDC says it is investigating other cyclosporiasis illnesses across the country that are unrelated to the Taco Bell outbreak — and the overall numbers are far larger. The agency has logged well over a thousand laboratory-confirmed, domestically acquired infections spanning dozens of states since the start of May, with thousands of additional cases still being analyzed. State and local health departments have reported thousands more that are not yet lab-confirmed, with Michigan and Ohio accounting for a large share.
The true toll is almost certainly higher than any single figure suggests. Many people recover on their own without ever being tested, and because it can take up to six weeks to confirm that someone is part of a Cyclospora outbreak, recent illnesses may not yet be counted. That reporting lag is why the CDC has moved to publishing weekly surveillance updates this year.
Symptoms and what to do
Cyclosporiasis typically brings watery — sometimes described as explosive — diarrhea, along with stomach cramps, nausea, loss of appetite, fatigue, low-grade fever and vomiting. Symptoms can appear about a week after exposure and, if untreated, may last weeks and even come and go, with people feeling better before relapsing.
The good news is that the infection is treatable. Doctors typically prescribe a course of antibiotics, and staying hydrated is important while recovering. Anyone with prolonged or severe diarrhea — especially with signs of dehydration such as dizziness, dry mouth or reduced urination — should contact a healthcare provider, who can test a stool sample specifically for the parasite (standard tests don't always catch it unless doctors know to look). As a general precaution during produce-linked outbreaks, washing fresh fruits and vegetables helps but does not reliably remove Cyclospora, so following specific CDC and FDA advisories about which products to avoid is the more reliable protection.
This is a developing public health investigation, and officials may update the affected products, states and case counts as more testing is completed.
