Updated: May 21, 2026
What is Cyclosporiasis?
Cyclosporiasis is a diarrheal illness caused by the protozoan parasite, Cyclospora cayetanensis, also known as Cyclospora. Cyclospora is a single-celled organism that is too small to be seen without a microscope.
What are the symptoms?
Cyclosporiasis is not generally thought to be life-threatening. The parasite usually causes watery diarrhea with frequent (and sometimes explosive) bowel movements. Other symptoms can include loss of appetite, loss of weight, bloating, increased gas, stomach cramps, nausea, vomiting, muscle aches, low-grade fever, and fatigue. The incubation period, or the time between being infected and becoming sick, is usually about 1 week. Some individuals who are infected with Cyclospora may not exhibit any symptoms.
How is Cyclospora treated?
If you are experiencing symptoms of a Cyclospora infection, please consult with your health care provider. While trimethoprim/sulfamethoxazole (a sulfa drug sold under the trade names Bactrim*, Septra*, and Cotrim*) is generally recognized as the usual therapy for Cyclospora infection, your health care provider should be able to assist in determining the best therapy for you. Don’t forget to inform your health care provider if you are allergic to sulfa drugs so you can discuss other potential options. Additionally, anti-diarrheal drugs may help reduce diarrhea, but a health care provider should also be consulted before such medicine is taken.
Most people who have healthy immune systems will recover without treatment. However, if not treated, the illness may last anywhere from a few days to a month or longer. In addition, symptoms may seem to go away only to return one or more times (relapse). People who are in poor health or who have weakened immune systems may be at higher risk for severe or prolonged illness.
How do people catch this disease?
Cyclospora is spread by people drinking water or eating food that was contaminated with infected stool. For example, outbreaks of cyclosporiasis have been linked to various types of fresh produce. Cyclospora requires at least 1 to 2 weeks in the environment (outside the body) to become infectious after being passed in a bowel movement. As a result, direct person-to-person transmission is unlikely. Additionally, it is not known if animals can be infected and spread infection to people. It has become an increasingly recognized cause of persistent diarrhea in both U.S. residents and returning travelers.
What can be done to stop the spread of this disease?
- Wash your hands before and after handling food.
- Wash all fruits and vegetables before eating.
- Avoid water or food that may be contaminated with stool.
- If you are traveling to areas where cyclosporiasis is endemic (such as tropical and subtropical regions), it's important to know that standard chemical disinfection, or sanitization of food or water, is unlikely to eliminate the risk of Cyclospora.