Cyclosporiasis Outbreak 2026
Featured Expert
July 14, 2026
A recent outbreak of cyclosporiasis is affecting parts of the U.S., with cases reported in more than 30 states. State and federal agencies are investigating these outbreaks and the source of the illness.
Cynthia Louise Sears, an expert in foodborne and intestinal infections and microbiome program leader of the Bloomberg~Kimmel Institute for Cancer Immunotherapy at Johns Hopkins Medicine, provides an overview of the situation and what you should know.
Key Points
- Cyclosporiasis is acquired when you eat foods contaminated with the parasite Cyclospora cayetanensis, which causes the infection.
- The infection most commonly causes diarrhea, and can also cause various other gastrointestinal symptoms, as well as dehydration.
- It’s unclear what is causing this outbreak, but previous outbreaks were linked to bagged salads, leafy greens, fresh basil, fresh cilantro, raspberries and green onions.
- Cyclosporiasis can be treated with antibiotics, and doctors may also recommend antidiarrheal medications.
What is cyclosporiasis?
Cyclosporiasis is an intestinal infection caused by the parasite Cyclospora cayetanensis.
How is cyclosporiasis transmitted?
People can become infected when they drink water or eat raw food, usually raw produce, that is carrying the parasite. Food picks up the parasite most often through water supplies that are infected with human feces.
Cyclosporiasis is not transmitted via person-to-person contact.
What are the symptoms of cyclosporiasis?
- Diarrhea is the main symptom. It can be acute or protracted, lasting weeks or months if untreated.
- Other symptoms include:
- nausea
- vomiting
- loss of appetite
- abdominal cramping
- bloating
- fatigue
- weight loss
When do symptoms of cyclosporiasis start?
Symptoms usually start within a week of ingesting the parasite.
What should I do if I think I have cyclosporiasis?
Contact your physician’s office or the clinic you attend for your stool to be tested for the parasite. For any diarrheal illness, drinking fluids to remain hydrated is important. There are many causes of diarrhea, and since Cyclospora infection is treatable with a specific antibiotic (below), getting diagnosed is important. If the diarrhea is severe and you are dizzy when standing or feel your heart rate speed up, you should seek care at an urgent care center or hospital.
How is it diagnosed?
Cyclosporiasis is diagnosed through a stool exam. People infected with cyclosporiasis shed it in their stool.
How is cyclosporiasis treated?
It is treated with the antibiotic trimethoprim/sulfamethoxazole. Your doctor may also recommend antidiarrheal medications and hydration. Some infections will go away on their own, but treatment is recommended for confirmed cases of cyclosporiasis.
How can I protect myself from acquiring cyclosporiasis?
- Wash fruits and vegetables before eating them. Cooking them may kill the parasite. Previous outbreaks were linked to bagged salad mixes and kits, fresh cilantro, fresh basil, raspberries, snow peas and green onions.
- Avoid drinking untreated water from lakes, streams, springs or other untreated water sources.
- Avoid touching human or animal feces.
- Wash your hands after using the toilet, after changing diapers and before handling food or eating.
What is the risk of getting cyclosporiasis?
The risk is high if you eat something contaminated, as it only takes a few oocysts (the infectious zygote of the parasite) to infect a person. Cyclosporiasis is not transmitted via person-to-person contact.
What should immunocompromised people know about cyclosporiasis?
For most causes of diarrhea, immunocompromised people face a greater risk of severe infection. If you are immunocompromised and suspect that you have cyclosporiasis, contacting your physician or care clinic is important for early diagnosis and antibiotic therapy if your stool is positive for Cyclospora.
How does Johns Hopkins prepare for outbreaks of infections like cyclosporiasis?
Johns Hopkins Medicine collaborates closely with the broader institution and regional public health partners to coordinate responses to infectious disease outbreaks. Physicians are alerted during active outbreaks so they can promptly diagnose and treat patients, and discuss preventive measures with them.
What is the source of the current U.S. outbreak of cyclosporiasis?
The source of the current outbreak is not known, but previous outbreaks have been linked to imported fresh produce, including bagged salads, leafy greens, fresh basil, fresh cilantro and raspberries.
More About the 2026 Cyclosporiasis Outbreak
Since May 1, 2026, the Centers for Disease Control and Prevention has received 843 confirmed domestic cases of cyclosporiasis, and is aware of more than 1,500 cases that need to be confirmed. Multiple states have reported an increase in cases compared with last year.
Medically reviewed by Cynthia Sears, M.D.
