What Is This Cyclosporiasis Outbreak? Causes, Symptoms, and How to Protect Yourself
Did you think washing your salad was enough to protect you from any risk? In the United States, an outbreak of cyclosporiasis is underway—an infection caused by the protozoan Cyclospora cayetanensis—transmitted primarily through the consumption of contaminated food and water. While typically between 1,000 and 2,000 cases are recorded each year, the current outbreak has already far exceeded those numbers, with Michigan alone reporting more than 6,100 cases as of July 20, 2026. Health officials say this is likely the largest cyclosporiasis outbreak in U.S. history.
Here is everything you need to know about the outbreak, its causes, symptoms, and the most effective ways to protect yourself.
The Scope of the Outbreak
The 2026 cyclosporiasis outbreak began around May 1, which marks the start of the annual cyclosporiasis season in the United States. As of mid-July, the CDC had confirmed 1,645 domestically acquired cases across 34 states, with more than 5,100 additional cases requiring further analysis. By July 20, Michigan alone had reported 6,148 confirmed cases, a staggering number compared to the state's typical annual average of roughly 50 cases.
The outbreak has hit the Midwest particularly hard. A multistate cluster involving Michigan, Ohio, West Virginia, and Kentucky has been linked to a common food source. As of July 17, the CDC identified shredded iceberg lettuce served at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio, and West Virginia as the source of infections in that cluster. Taylor Farms de Mexico, the supplier, issued a voluntary recall of its iceberg lettuce products.
At least 141 people (9%) have been hospitalized, and patients have ranged in age from 2 to 95 years. No deaths have been reported.
What Is Cyclosporiasis?
Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. The parasite infects the small intestine and causes gastrointestinal symptoms that can persist for days, weeks, or even months if left untreated.
Unlike many other foodborne illnesses, cyclosporiasis is not transmitted directly from person to person. The parasites shed during infection are not immediately infectious, meaning transmission occurs exclusively through the fecal-oral route via ingestion of contaminated food or water
How Do People Get Infected?
People become infected by consuming food or water contaminated with the Cyclospora parasite. In the United States, foodborne outbreaks have been linked to various types of fresh produce, particularly:
The current outbreak has been linked to shredded iceberg lettuce sourced from Mexico. However, contamination can occur at multiple points along the supply chain—typically at the farm or irrigation level—making traceback investigations particularly difficult.
Symptoms: What to Watch For
Symptoms of cyclosporiasis typically begin about one week after exposure, though onset can range from 2 to 14 days.
The most common symptoms include:
Less common symptoms:
Without treatment, symptoms can follow a remitting-relapsing course—meaning they may go away and then return—lasting anywhere from a few days to more than a month.
When to seek medical attention
If you experience watery diarrhea lasting more than a few days, contact your healthcare provider. Because Cyclospora is not detected by standard stool cultures, you may need to specifically request a Cyclospora test. This is especially important for young children, older adults, and people with weakened immune systems, who are at increased risk for severe illness and complications.
Treatment
Cyclosporiasis is treatable with antibiotics. The recommended treatment is trimethoprim-sulfamethoxazole (brand names Bactrim or Septra). Supportive care to prevent dehydration is also essential.
Without treatment, the illness can be prolonged and may relapse. Anyone experiencing persistent diarrhea should seek medical evaluation promptly.
How to Protect Yourself
While investigators continue to trace the source of the outbreak, public health officials recommend the following preventive measures:
1. Wash all fresh produce thoroughly
Rinse fruits and vegetables under running water before eating, cutting, or cooking. Scrub firm produce such as cucumbers and melons with a clean scrub brush.
Important: Washing produce may not completely eliminate the risk, but it is still recommended by the CDC.
2. Cook produce when possible
Cooking food to an internal temperature of at least 158°F (70°C) is the most effective way to eliminate the parasite.
3. Practice good hand hygiene
Wash your hands thoroughly with soap and water before and after handling food. Alcohol-based hand sanitizers are not effective against Cyclospora.
4. Avoid high-risk foods during outbreaks
Given the current outbreak, consider avoiding raw leafy greens and salads from commercial sources, especially if you live in or have recently traveled to affected states.
5. Stay informed
Follow updates from the CDC and your state health department regarding food recalls and outbreak developments.
A Word of Caution
One of the challenges with cyclosporiasis is the delay between exposure and symptoms—often about a week or more. By the time people become sick, they may not remember what they ate, making it difficult to pinpoint the source.
Additionally, changes to federal foodborne disease surveillance—beginning in July 2025—may have made outbreak detection more challenging, placing greater responsibility on state and local health departments.
The Bottom Line
The 2026 cyclosporiasis outbreak is one of the largest in U.S. history, with thousands of confirmed cases across more than 30 states. The infection is caused by consuming contaminated food or water—most commonly fresh produce like leafy greens. Symptoms include prolonged watery diarrhea, fatigue, nausea, and weight loss, typically appearing about a week after exposure.
If you experience persistent diarrhea, contact your healthcare provider and specifically ask to be tested for Cyclospora. The infection is treatable with antibiotics, but without treatment, it can last for weeks or longer.
In the meantime, thoroughly wash all produce, cook food when possible, and stay informed about ongoing outbreak investigations and food recalls.
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