CDC Warns of Cyclosporiasis Outbreak: 145+ Cases Across 17 States as Parasitic Infection Spreads

CDC Issues Alert as Cyclosporiasis Cases Surge Across the United States

A rapidly expanding outbreak of cyclosporiasis, a parasitic intestinal infection caused by the microscopic parasite Cyclospora cayetanensis, has prompted a national alert from the U.S. Centers for Disease Control and Prevention (CDC), with at least 145 confirmed domestic cases reported across 17 states as of mid-June 2026.

Health authorities are also investigating a dramatic surge in Michigan, where more than 700 additional cases have been reported in recent weeks, signaling what officials describe as a “sudden and large” increase well beyond the norm for the state. The outbreak, which typically peaks during the spring and summer months, has public health officials on high alert and urging healthcare providers and the public to remain vigilant.

What Is Cyclosporiasis?

Cyclosporiasis is a gastrointestinal illness caused by Cyclospora cayetanensis, a single-celled microscopic parasite that infects the small intestine. The parasite is transmitted through the fecal-oral route, meaning people become infected when they consume food or water contaminated with feces containing the parasite.

Unlike many foodborne infections, Cyclospora requires time outside the body — typically one to two weeks — before it becomes infectious. This means direct person-to-person transmission is highly unlikely. Instead, outbreaks are consistently linked to contaminated fresh produce imported or grown domestically.

Current Outbreak Status: What the Data Shows

According to the most recent CDC surveillance data as of June 16, 2026:

• 145 domestic cases confirmed across 17 U.S. states
• 20 hospitalizations reported, with zero deaths to date
• Median patient age of 42 (range: 5 to 86 years)
• 61% of cases are female
• Median illness onset: May 13, 2026 (range: May 1 – June 6)
• 45 travel-related cases among individuals who consumed contaminated food or water outside the U.S.

The situation is evolving rapidly. Michigan alone has reported over 708 cases since late June — more than 10 times the state’s typical annual total of 50 infections. Ohio has confirmed at least 170 cases, while Indiana, New York, and North Carolina have each reported more than 100 cases in recent weeks.

States Affected by the Cyclospora Outbreak

The 17 states reporting domestically acquired cases include: Alaska, Louisiana, Texas, Colorado, Georgia, Florida, North Carolina, Virginia, Tennessee, Illinois, Wisconsin, Ohio, Pennsylvania, New York, New Jersey, Connecticut, and Massachusetts. Michigan is now reporting additional cases beyond the initial CDC surveillance period.

Health officials caution that the true number of cases is likely significantly higher than reported, as many people recover without seeking medical care or being tested for Cyclospora specifically.

Symptoms to Watch For

Symptoms of cyclosporiasis typically appear 7 to 10 days after ingesting the parasite, though the incubation period can range from 2 to 14 days. The most commonly reported symptoms include:

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

Without treatment, symptoms can persist for several weeks, with relapses of diarrhea and fatigue common. Immunocompromised individuals may experience prolonged or more severe illness.

How Cyclosporiasis Spreads

In the United States, cyclosporiasis outbreaks have been historically linked to fresh produce items, including:

• Basil and cilantro
• Raspberries and blackberries
• Snow peas and snap peas
• Bagged salad mixes and romaine lettuce
• Pre-cut vegetable trays

The CDC and U.S. Food and Drug Administration (FDA) are actively investigating multiple multistate clusters, though no single food source, grower, or supplier has been identified as the common link yet. Officials emphasize that this is not one unified outbreak but rather multiple clusters under investigation simultaneously.

Diagnosis and Treatment

Cyclosporiasis is diagnosed through stool microscopy to identify Cyclospora oocysts. Multiple stool samples may be necessary because parasite shedding can be intermittent. Healthcare providers should specifically request testing for Cyclospora, as it is not included in routine stool culture panels.

The standard treatment is the oral antibiotic trimethoprim-sulfamethoxazole (TMP-SMX), commonly sold under brand names Bactrim, Septra, and Cotrim, taken for 7 to 10 days. For patients with sulfa allergies, alternative antibiotic regimens should be discussed with an infectious disease specialist.

Supportive care, including adequate hydration and electrolyte management, is essential during recovery.

Prevention: Protecting Yourself and Your Family

While the source of the current outbreak remains under investigation, general food safety practices can significantly reduce your risk:

• Wash all fresh produce thoroughly under running water before eating, cutting, or cooking
• Scrub firm fruits and vegetables with a clean produce brush
• Cut away bruised or damaged parts of fruits and vegetables
• Refrigerate pre-prepared or pre-cut produce promptly
• Practice proper hand hygiene — wash hands with soap and water after using the bathroom, changing diapers, and before handling food
• Be cautious with imported produce during outbreak seasons

It is important to note that Cyclospora is not killed by standard chlorination levels used in drinking water treatment, making proper food handling and hand hygiene even more critical.

When to See a Doctor

If you experience persistent watery diarrhea, especially if accompanied by abdominal cramping, nausea, or fatigue, and you live in or have recently visited an affected state, seek medical attention. The CDC recommends that anyone with symptoms lasting more than a few days consult their healthcare provider and specifically ask about testing for Cyclospora.

“If you’re in an area that’s been affected and you have sudden ongoing watery diarrhea, you should definitely seek a physician and get treatment,” infectious disease experts advise.

FAQ: Your Cyclosporiasis Questions Answered

Can cyclosporiasis be spread from person to person?

No. Cyclospora requires one to two weeks outside the body to become infectious (sporulate), so direct person-to-person transmission is highly unlikely.

How long does cyclosporiasis last without treatment?

Symptoms can persist for several weeks if untreated, with relapses of diarrhea and fatigue common. With appropriate antibiotic treatment, most patients recover within days.

Is cyclosporiasis life-threatening?

It is rarely life-threatening. No deaths have been reported in the current 2026 outbreak. However, severe dehydration can occur, particularly in young children, older adults, and immunocompromised individuals.

Can I prevent infection by washing my produce?

Thoroughly washing produce reduces your risk but may not eliminate all Cyclospora oocysts if the produce is heavily contaminated. Cooking kills the parasite.

Is there a vaccine for cyclosporiasis?

No vaccine is currently available. Prevention relies on food safety practices and hygiene measures.

Why are cases rising in summer?

Cyclosporiasis follows a seasonal pattern in the U.S., with cases typically peaking between May and August. The spring and summer months coincide with increased consumption of fresh produce, which is the primary vehicle for transmission.

The Bottom Line

The 2026 cyclosporiasis outbreak is a significant and evolving public health event. With hundreds of cases confirmed across nearly 20 states and investigations ongoing, the CDC urges healthcare providers to maintain a high index of suspicion for cyclosporiasis in patients presenting with acute watery diarrhea, particularly if they have no history of international travel.

For the public, the message is clear: practice diligent food safety, wash your produce thoroughly, and do not hesitate to seek medical care if you develop persistent gastrointestinal symptoms. The outbreak serves as a stark reminder that foodborne illnesses remain a serious, seasonally recurring threat to public health across the United States.

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