Source Identified in Growing Cyclosporiasis Outbreak: How to Avoid the Severe Stomach Illness
An infectious disease specialist explains how to reduce your risk of cyclosporiasis, the food-borne illness currently spreading throughout the United States.
Federal public health officials have identified the source of an outbreak of cyclosporiasis, a parasite that has caused a spike in severe diarrhea around the United States. Cases in Indiana, Kentucky, Michigan, Ohio, and West Virginia were all linked to shredded iceberg lettuce from a single source and served at local Taco Bell restaurants.
The Centers for Disease Control and Prevention and U.S. Food & Drug Administration are now advising the public not to eat iceberg lettuce served at Taco Bells in those states, and if you’ve recently purchased food with lettuce from those locations to carefully clean and sanitize any surfaces or containers that it touched.
Cyclosporiasis develops when a person becomes infected by a microscopic parasite called Cyclospora cayetanensis. The illness is transmitted through contaminated food and water, and the main symptom is frequent diarrhea.
The recent outbreak has sickened at least 1,645 people across 34 states, but the actual number of cases is likely higher. There have been 517 cases in New York State so far this year, with 273 cases in New York City, compared to the average 500-700 cases in New York in all of 2024 and 2025. Several other states are also reporting higher than usual case counts.
To learn more about how you can keep yourself safe from this parasite and avoid getting a stomach bug, Health Matters spoke with Dr. Clare DeLaurentis, an infectious disease specialist with NewYork-Presbyterian/Columbia University Irving Medical Center.
How does cyclosporiasis spread?
Dr. DeLaurentis: Cyclosporiasis generally spreads via food or water that’s been contaminated with human feces, often through irrigation systems used to water fresh fruit and produce.
It does not spread directly from person to person. Even when someone passes the parasite in their stool, it takes weeks for the parasite to mature to a state where it is infectious.
How is it prevented?
Dr. DeLaurentis: The best way to prevent cyclosporiasis is to practice good hygiene, specifically washing your hands with soap and water before handling food and after using the restroom or changing diapers. Alcohol based hand sanitizers are not as effective as soap and water for killing Cyclosporiasis. And avoid drinking water directly from streams, lakes, springs, or swimming pools, which may be contaminated.
Peeling fruits and cooking vegetables can kill Cyclospora. For uncooked fruits and vegetables, we would recommend washing them thoroughly with running water. We do not yet know the exact source (or more likely sources) of this year's increase in cases, but historically foods such as bagged lettuce or salad mixes, herbs such as basil and cilantro, and fruits like raspberries have been implicated.
Understandably, people may also be concerned about eating raw fruits and vegetables in a restaurant. While there may be an increased risk of transmission, it depends on the level of risk with which an individual is comfortable.
What are the symptoms? Do they differ from other diarrheal illnesses?
Dr. DeLaurentis: The main symptom is watery diarrhea that can be frequent or "explosive." Other symptoms can include loss of appetite, weight loss, bloating, nausea, and low-grade fever. Most people develop symptoms about one week after becoming infected, but it can range from two days to two weeks.
Ultimately a diagnosis requires specialized stool testing since the symptoms are similar to many other diarrheal illnesses, like giardia, cryptosporidium, or norovirus. So if you experience symptoms like persistent diarrhea, dehydration, or weight loss, talk to your doctor to see if you should be tested.
How is it treated? Is it fatal?
Dr. DeLaurentis: Cyclospora is generally not life-threatening and most people with healthy immune systems will recover without treatment, though some may have symptoms that recur, signifying a relapse. People with weakened immune systems, older adults, and young children may be at increased risk for severe or prolonged illness.
If a diagnosis is confirmed, the recommended treatment is a one-week course of the antibiotic trimethoprim-sulfamethoxazole, also known as Bactrim or Septra. Treatment can shorten the duration of symptoms and help prevent a relapse. Regardless, if you are experiencing persistent diarrhea, it’s important to hydrate by drinking lots of fluids, including those with electrolytes, like sports drinks or pediatric electrolyte solutions for children.
Is there anything else people should know about cyclosporiasis?
Dr. DeLaurentis: Now that a source has been identified, additional restaurants, products, or distribution channels may be implicated. Look for updated guidance from public health authorities as more information becomes available. In the meantime, be diligent about cleaning raw fruits and vegetables and before you eat them, and make sure you and your loved ones are practicing good hand hygiene.
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