CDC Warns of Cyclosporiasis Outbreak — 843 Cases Across 31 States in 2026

The U.S. Centers for Disease Control and Prevention (CDC) is investigating a major cyclosporiasis outbreak that has rapidly escalated across the United States. As of July 9, 2026, health officials have confirmed 843 cases spanning 31 states, with more than 1,500 additional suspected cases under investigation. The outbreak has already resulted in at least 86 hospitalizations, though no deaths have been reported to date.

This emerging public health threat has drawn urgent attention from infectious disease specialists, infection prevention and control (IPC) professionals, and public health authorities nationwide. Here is everything healthcare professionals and the public need to know.

What Is Cyclosporiasis?

Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. The parasite enters the body through contaminated food or water — typically fresh produce that has been contaminated by human feces during growing, harvesting, or processing.

Unlike many foodborne illnesses, cyclosporiasis is not transmitted from person to person. Infection occurs exclusively through ingestion of contaminated food or water, making it a foodborne and waterborne disease rather than a contagious one.

Key Facts About Cyclospora

• Incubation period: Symptoms typically appear 7 to 10 days after exposure, though onset can range from 2 days to 2 weeks
• Duration: Symptoms can last from a few days to several weeks if untreated
• Seasonality: Cases peak between May and August in the United States, earning it the label of a “summer parasite”
• Environment: Cyclospora thrives in warm, damp conditions, raising concerns that climate change may expand its geographic reach

Current Outbreak Situation — A Rapidly Escalating Crisis

What began as 145 confirmed cases across 17 states in mid-June has ballooned into one of the largest cyclosporiasis outbreaks in recent U.S. history. The CDC data as of July 9, 2026, tells a troubling story:

• 843 confirmed domestic cases reported to the CDC since May 1, 2026
• 86 hospitalizations among confirmed cases (approximately 10% hospitalization rate)
• 31 states affected, with Michigan, New York, Texas, and Illinois among the hardest hit
• More than 1,500 suspected cases requiring further analysis to confirm domestically acquired infection
• Median patient age: 44 years (range: 5–88)
• 59% of cases are female

Michigan: The Epicentre

Michigan has been disproportionately affected. The state’s health department reports more than 1,500 cases — a staggering increase from the 40 to 50 cases typically seen in an average year. Dr. Natasha Bagdasarian, Chief Medical Executive for the state, told TIME that authorities were first alerted to a potential widespread outbreak in early July. The state is now conducting in-depth interviews with confirmed patients, asking where they ate, what they ordered, and what groceries they purchased, in an effort to trace the source.

Symptoms of Cyclosporiasis

Healthcare workers should maintain a high index of suspicion for cyclosporiasis in patients presenting with gastrointestinal symptoms, particularly if symptoms persist beyond a few days. Key symptoms include:

• Watery diarrhea — often profuse and sometimes described as “explosive”
• Abdominal cramping and pain
• Nausea and loss of appetite
• Fatigue and malaise
• Low-grade fever (less common)
• Weight loss

Cyclosporiasis differs from typical food poisoning cases: symptoms tend to remain in the lower gastrointestinal tract, vomiting is uncommon, and the illness can last for weeks. Some patients experience relapsing symptoms — periods of improvement followed by recurrence.

Diagnosis: A Challenge for Clinicians

Diagnosing cyclosporiasis presents a unique challenge because routine stool testing panels do not typically include Cyclospora. Dr. Linda Yancey, an infectious disease specialist at Memorial Hermann Health System in Texas, notes that doctors must specifically request a Cyclospora stain to detect the parasite. Multiple stool samples may be necessary, as parasite shedding can be intermittent.

The illness is nationally notifiable in 47 states, the District of Columbia, and New York City, meaning healthcare providers are legally required to report confirmed cases to local health departments.

Treatment and Management

Cyclosporiasis is treatable. The standard course is a combination antibiotic regimen of trimethoprim-sulfamethoxazole (TMP-SMX), commonly known as Bactrim or Septra. For patients with sulfa allergies, alternative antibiotic regimens should be considered in consultation with infectious disease specialists.

Supportive care is critical:

• Adequate hydration to prevent dehydration from prolonged diarrhea
• Electrolyte monitoring and replacement
• Symptom management as needed

Most patients with healthy immune systems recover fully with appropriate treatment. However, immunocompromised individuals may experience prolonged or more severe illness and may require extended antibiotic therapy.

How to Reduce Your Risk

The CDC recommends these preventive measures:

• Wash all fresh produce thoroughly under running water before eating
• Wash hands and kitchen surfaces thoroughly after handling raw produce
• Cook food when possible — heat destroys the Cyclospora parasite
• Drink safe water — avoid untreated water from lakes, rivers, or wells
• Seek medical attention if watery diarrhea persists for more than a few days

It is important to note that Cyclospora is resistant to chlorine and other standard water treatments, making washing alone insufficient when water is contaminated.

Frequently Asked Questions (FAQ)

Q: Is cyclosporiasis contagious from person to person?

A: No. Cyclosporiasis is not transmitted directly from person to person. The parasite must mature outside the body (a process called sporulation) before it can cause infection, which typically occurs in contaminated food or water.

Q: How long does cyclosporiasis last?

A: Without treatment, symptoms can last from a few days to several weeks. With appropriate antibiotic treatment, most patients recover within days. Symptoms may come and go (relapse) in some cases.

Q: Can cyclosporiasis be fatal?

A: While rarely fatal, the CDC reports that approximately 10% of confirmed cases in the current outbreak have required hospitalization. No deaths have been reported in this outbreak.

Q: What foods have been linked to past Cyclospora outbreaks?

A: Previous outbreaks have been linked to fresh produce such as cilantro, basil, leafy greens, raspberries, salad mixes, and snow peas. The current outbreak has not yet identified a specific food source.

Q: Should I be tested if I have symptoms?

A: Yes. See your healthcare provider and specifically ask about Cyclospora testing. Standard stool panels often do not include this parasite — the doctor must specifically order a Cyclospora stain.

Q: Can I prevent cyclosporiasis?

A: Thoroughly washing all fresh produce and practicing good hand hygiene are the most effective prevention measures. However, because Cyclospora can be difficult to remove entirely through washing alone, cooking produce provides the highest level of protection.

What Comes Next

The CDC, FDA, and state health departments are actively investigating multiple clusters of cases. While no single contaminated food source has been identified, investigations are ongoing. Given the 6-week reporting lag between illness onset and case confirmation at the national level, health officials anticipate case counts will continue to rise as more data is received.

For healthcare professionals, the key takeaways are clear: maintain clinical suspicion for cyclosporiasis in patients with persistent watery diarrhea, specifically request the appropriate diagnostic testing, and promptly report confirmed cases to local health departments. Early recognition and reporting remain the most critical tools in controlling this emerging seasonal threat.