What is Cyclospora? The Common Symptoms & Treatment

Cyclospora is a microscopic, single-celled parasite that infects the small intestine. The infection it causes, called cyclosporiasis, is a foodborne gastrointestinal illness that most commonly results in prolonged watery diarrhea.

People become infected after consuming food or water contaminated with Cyclospora cayetanensis . Symptoms generally begin about one week after exposure, although the incubation period may range from two days to two weeks or longer. While cyclosporiasis is not usually life-threatening, it can cause dehydration and prolonged illness, particularly in older adults, people in poor health, and those with weakened immune systems. Learn more from the CDC .

What causes Cyclospora infection is the ingestion of food or water contaminated with human feces containing the parasite. Fresh produce may become contaminated through unsafe irrigation water, washing water, agricultural practices, or food handling.

Direct person-to-person transmission is unlikely. After leaving the body, the parasite typically needs at least one to two weeks in the environment to mature and become infectious.

People may have an increased risk if they:

• Eat raw or undercooked contaminated produce
• Drink untreated or contaminated water
• Travel to tropical or subtropical regions where Cyclospora is more common
• Consume food identified in an active outbreak or recall

The most characteristic of the Cyclospora symptoms is frequent watery diarrhea, which may sometimes be sudden or severe. Other common symptoms include:

• Loss of appetite
• Unintentional weight loss
• Abdominal cramping
• Bloating and increased gas
• Nausea
• Fatigue

Less common symptoms include vomiting, headache, body aches, low-grade fever, and other flu-like symptoms. Without appropriate treatment, symptoms may continue for several weeks or temporarily improve before returning. Review the CDC symptom guidance .

Patients should contact a healthcare provider if diarrhea lasts more than three days or is accompanied by signs of dehydration, such as reduced urination, dry mouth, weakness, or dizziness. Older adults, pregnant patients, young children, and immunocompromised individuals should seek medical advice promptly.

How is Cyclospora diagnosed?

Healthcare providers typically diagnose cyclosporiasis by ordering a stool test specifically designed to detect Cyclospora. Because routine stool cultures do not identify this parasite, specialized stool PCR testing or ova-and-parasite examinations may be needed. Sometimes more than one stool sample is required.

TMP-SMX which is also known atrimethoprim-sulfamethoxazole is the only proven first-line antimicrobial treatment currently recommended by the CDC for the treatment of Cyclospora.A healthcare provider should determine the appropriate dose and treatment duration based on the patient's age, medical history, immune status, medications, allergies, pregnancy status, and kidney function. TMP-SMX which is also known atrimethoprim-sulfamethoxazole is the only proven first-line antimicrobial treatment currently recommended by the CDC for the treatment of Cyclospora.

A healthcare provider should determine the appropriate dose and treatment duration based on the patient's age, medical history, immune status, medications, allergies, pregnancy status, and kidney function.

Patients should also rest and drink adequate fluids to replace water and electrolytes lost through diarrhea. People allergic to sulfonamide medications should speak with their healthcare provider because no consistently effective standard alternative has been identified. See the CDC's clinical treatment guidance .

In the United States, outbreaks have previously been associated with imported fresh produce, including:

• Basil
• Cilantro
• Lettuce and other leafy greens
• Raspberries
• Snow peas
• Fresh vegetable trays and salad mixtures

A 2026 multistate outbreak was also linked to recalled iceberg lettuce. However, Cyclospora is not naturally present in a particular fruit or vegetable; contamination can affect different foods. Consumers should therefore follow current CDC and FDA food-safety alerts rather than avoid one food permanently. View the CDC's current outbreak information .

To help prevent infection:

• Wash hands with soap and water before and after preparing produce.
• Rinse fruits and vegetables thoroughly under running water, including produce labeled ​"pre-washed."
• Scrub firm produce with a clean produce brush.
• Remove bruised or damaged areas.
• Refrigerate cut, peeled, or cooked produce within two hours.
• Avoid recalled products and follow food-safety alerts.
• Cook produce to at least 158°F (70°C) when practical.

Washing reduces risk but cannot guarantee complete removal of Cyclospora. Routine chemical sanitizers are also unlikely to kill the parasite. Follow the CDC's prevention recommendations .