This summer, a common salad ingredient became the center of a major foodborne illness outbreak across the United States. The Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) linked thousands of cases of cyclosporiasis to iceberg lettuce sourced from central Mexico and processed by Taylor Farms of Mexico. As of August 27, 2026, 11,458 illnesses had been reported across 20 states, with 495 hospitalizations and two deaths. Some of the states with reported cases include Arkansas, Kansas, Kentucky, Massachusetts, Maine, Michigan, New Hampshire, North Carolina, Pennsylvania, and New Jersey.
But what exactly is causing people to become sick? Cyclosporiasis is an intestinal infection caused by Cyclospora cayetanensis, a microscopic, single-celled parasite. Unlike bacteria or viruses, Cyclospora has a complex life cycle. The parasite can contaminate food or water when it comes into contact with human feces. Once swallowed, the parasite reaches the intestines, where it infects the intestinal lining and develops into an oocyst, an egg-like structure that eventually leaves the body through stool. Importantly, these oocysts need time in the environment before they become infectious, making direct person-to-person transmission unlikely.
The infection can be particularly unpleasant because symptoms do not always appear immediately. They often begin about a week after consuming contaminated food or water. The most common symptom is watery diarrhea, but people may also experience abdominal cramps, bloating, nausea, vomiting, loss of appetite, and fatigue. Some people develop a mild fever or lose weight. Symptoms can last for weeks and may disappear temporarily before returning.
Most people with healthy immune systems eventually recover, but the infection can be more serious for people with weakened immune systems. Children can also become dehydrated more quickly from prolonged diarrhea. Mayo Clinic recommends contacting a healthcare professional if diarrhea lasts more than one day in children or two days in adults, particularly if there are signs of dehydration. Immediate medical attention is important for severe abdominal pain, high fever, bloody or black stools, inability to drink enough fluids, or confusion.
Luckily, there are a number of ways that people can protect themselves. During an outbreak, consumers should follow public health recommendations and avoid recalled foods. More generally, washing hands with soap and water for at least 20 seconds, rinsing fresh produce under running water, removing outer leaves from lettuce, and cleaning kitchen utensils can reduce the risk. However, contaminated produce can look, smell and taste normal, so these steps cannot guarantee that food is parasite-free.
The recalled Taylor Farms iceberg lettuce is considered off the market, but the outbreak investigation has not yet been completely resolved. FDA inspections and sampling in Mexico are ongoing, meaning scientists and public health officials are still working to understand how the contamination occurred and prevent another outbreak.
