The CDC has confirmed 4,173 cases of cyclosporiasis across 41 states since May 1, running at more than 16 times last year's pace, with 308 hospitalizations and no deaths reported so far. The outbreak is linked to contaminated iceberg lettuce, and some hospitals have removed leafy greens from their cafeterias as a precaution while investigators work to pinpoint the exact source.

What Is Cyclospora and How Does It Spread?

Cyclosporiasis is a gastrointestinal illness caused by a microscopic parasite called Cyclospora cayetanensis. People become infected by consuming contaminated food or water; the illness is not usually spread from person to person. The parasite is most common in tropical areas such as Central America, South America, Asia, and Africa, but outbreaks in the United States typically occur during spring and summer months.

The current outbreak's largest identified cluster spans five states: Indiana, Kentucky, Michigan, Ohio, and West Virginia. This cluster is tied to shredded iceberg lettuce served at Taco Bell, with Michigan and Ohio hit hardest. On July 17, Taylor Farms voluntarily recalled all iceberg lettuce sourced from central Mexico, a product distributed from June 29 through July 16 in 27 states and sold in both food service and retail locations, including Walmart's Marketside brand.

What Symptoms Should You Watch For?

Symptoms typically begin about one week after exposure, though the onset window can range from 2 to 14 days. The most common presentation is frequent, watery diarrhea paired with other gastrointestinal symptoms. Unlike other common stomach bugs, cyclosporiasis does not cause significant inflammation, so patients typically do not experience the severe abdominal pain or bloody diarrhea associated with infections like norovirus or salmonella.

One critical feature that sets cyclosporiasis apart is that untreated cases can follow a relapsing pattern, meaning symptoms may come and go over days to a month or longer. This makes it easy to miss on first evaluation, so patients whose stomach troubles keep returning deserve a second look during outbreak season.

How to Recognize and Report Cyclospora Symptoms

• Primary Symptom: Frequent, watery diarrhea that may come and go over time, especially if untreated
• Associated Symptoms: Loss of appetite, weight loss, bloating, increased gas, nausea, and fatigue; less commonly, low-grade fever and vomiting
• Diagnosis Method: Stool testing that specifically identifies Cyclospora oocysts; the parasite can be missed if the lab is not asked to look for it, so mention recent produce consumption and outbreak exposure to your healthcare provider
• Reporting Requirement: Cyclosporiasis is a reportable disease, so confirmed cases must be reported to local health departments to help investigators trace the source

What Is the Treatment?

The CDC-recommended treatment is trimethoprim-sulfamethoxazole, commonly known as Bactrim, along with rest and fluids to maintain hydration. Bactrim works by disrupting the parasite's ability to produce the folic acid it needs to replicate. Patients with sulfa allergies should discuss alternatives with their healthcare provider. Immunocompromised patients face higher risk of prolonged illness and should be encouraged to seek testing and treatment early.

How Can You Reduce Your Risk?

• Produce Washing: Washing produce reduces risk but may not fully remove Cyclospora oocysts, so patients at higher risk may reasonably avoid implicated categories of fresh produce until a source is identified
• Hand Hygiene: Alcohol-based hand sanitizer does not kill Cyclospora, so use soap and water for handwashing after handling produce
• Food Service Awareness: Be aware of current outbreak alerts in your area; some hospitals have temporarily removed certain salad bar items and leafy greens from patient and public food service areas as a precaution

Kalamazoo, Michigan-based Bronson Healthcare announced that it temporarily removed certain salad bar items, leafy greens, and other higher-risk fresh produce from both patient and public food service areas. South Bend, Indiana-based Beacon Health System removed all raw lettuce and leafy greens from its hospital cafeterias across Indiana and southwest Michigan and closed its Kalamazoo salad bar.

Why Is This Outbreak So Unusual?

By the same point last year, only 249 cases had been reported nationally. This year's count of 4,173 confirmed cases represents a dramatic spike, and the CDC notes that more than 7,400 additional cases are still under review for confirmation. Because cyclosporiasis is often underdiagnosed and underreported, the true number of infections is likely even higher. The outbreak is running at more than 16 times last year's pace, making it a significant public health concern.

What makes diagnosis tricky is that the parasite can be easily missed if laboratories are not specifically asked to look for it. Healthcare providers and patients need to connect the dots: recent consumption of fresh produce, especially lettuce, combined with relapsing watery diarrhea and fatigue should raise suspicion and prompt specific stool testing.