The nationwide Cyclospora outbreak continues to expand, with health officials reporting a sharp increase in illnesses and new clues about what may be driving the surge. While investigators have not yet identified a specific product or supplier, evidence is increasingly pointing toward lettuce and other leafy salad greens as a possible source of infection.
According to the Centers for Disease Control and Prevention (CDC), 843 laboratory-confirmed Cyclospora illnesses across 31 states had been reported as of July 10. However, federal officials caution that this number almost certainly underestimates the true scope of the outbreak. More than 1,500 additional cases are still being analyzed, meaning the official national total is expected to rise significantly in the coming weeks.
One of the biggest developments comes from Michigan, where the outbreak has grown at an alarming pace. State health officials now report 2,640 confirmed illnesses and 44 hospitalizations, an increase of more than 1,000 cases in just a few days. Ohio has also reported hundreds of illnesses this summer, bringing the combined total in the two states to well over 3,000 reported infections.
After conducting more than 1,000 patient interviews and reviewing grocery loyalty card data, restaurant receipts, and purchase histories, investigators say lettuce or salad greens repeatedly appear in exposure histories. Despite this finding, officials stress that the investigation is ongoing. No specific brand, grower, distributor, or supplier has been identified, and other food items have not yet been ruled out.
Cyclospora (Cyclospora cayetanensis) is a microscopic parasite that causes cyclosporiasis, an intestinal illness that can be particularly frustrating because symptoms often do not appear until about one week—or even up to two weeks—after eating contaminated food. That long incubation period makes traceback investigations especially difficult, as patients are asked to remember meals they ate days or even weeks earlier. Investigators frequently must rely on restaurant records, grocery receipts, and shopper card data to reconstruct what people consumed before becoming ill.
Unlike many common foodborne illnesses that resolve within a few days, Cyclospora infections can linger for weeks if left untreated. Patients commonly experience prolonged watery diarrhea, stomach cramps, bloating, nausea, fatigue, decreased appetite, and weight loss. Symptoms may improve temporarily before returning again, making the illness especially disruptive. Severe dehydration can lead to hospitalization, particularly in young children, older adults, and people with weakened immune systems.
Cyclospora has long been associated with fresh produce, including cilantro, basil, raspberries, snow peas, bagged salad mixes, and leafy greens. Because contamination generally occurs before produce reaches consumers, thoroughly washing fruits and vegetables may help reduce surface contamination but cannot be relied upon to completely eliminate the parasite.
Health officials emphasize that people experiencing persistent diarrhea should seek medical attention and ask specifically about Cyclospora testing. Routine stool testing does not always include the parasite unless it is specifically requested. When diagnosed, cyclosporiasis is typically treated with the antibiotic combination trimethoprim-sulfamethoxazole (TMP-SMX), commonly sold as Bactrim or Septra.
For now, consumers should remain informed but avoid jumping to conclusions about any particular product. Investigators continue working with state and federal agencies to identify the contaminated food responsible for the outbreak. Additional illnesses, traceback findings, or recalls may be announced as the investigation progresses.
