Cyclosporiasis is a parasitic infection of the small intestine caused by the protozoa Cyclospora cayetanensis. People contract cyclosporiasis by consuming contaminated food or water. In 1999, the CDC made cyclosporiasis a nationally reportable disease in the United States. Incidence of cyclosporiasis in the United States and other industrialized nations has increased significantly since it was discovered in 1979, likely due to the expanding availability of imported produce.


Symptoms of cyclosporiasis begin two to 11 days after infection. The most common symptom is frequent, watery diarrhea, but it can also manifest as alternating periods of diarrhea and constipation. Other symptoms include loss of appetite, bloating, flatulence, stomach cramps, nausea and vomiting, headaches, muscle aches, fever, fatigue, and weight loss. Symptoms can last up to four weeks. In some individuals, however, cyclospora infections are asymptomatic.

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The cyclospora parasite reproduces in the intestines of a person with cyclosporiasis. Young protozoa exit the body in a bowel movement but are not infectious at this stage. They reach maturity and become infectious in seven to 11 days. New people develop the infection by consuming food or water contaminated with infected feces. Fresh fruit and vegetables, including raspberries, lettuce, basil, cilantro, and snow peas, are the most common carriers. There has never been a case of cyclosporiasis linked to canned or frozen foods in the United States.

raspberries, fresh fruit, vegetables, contaminated Sean Gallup / Getty Images


Risk Factors and Prevalence

Cyclospora is common in the environment of tropical and subtropical regions in Latin America, Southeast Asia, and India. Travelers visiting these regions are at increased risk of developing cyclosporiasis, but outbreaks can happen anywhere and have increased steadily in the United States since 2014. Anyone can contract cyclosporiasis, but young children, the elderly, and people with weakened immune systems have a higher risk of infection.

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Cyclosporiasis is difficult to diagnose because the symptoms are similar to many other illnesses. Doctors base the diagnosis on symptoms and patient history, and lab tests can confirm. In most cases, the doctor will require the patients to submit multiple stool samples over several days because the protozoa are not present in every bowel movement. He or she may also test for other common pathogens to rule them out.

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Healthy people often recover from cyclosporiasis without medical intervention. A combination of antibiotics is effective against the parasite. People with sulfa allergies must rely on supportive treatment to manage their symptoms. Outpatient treatment includes anti-diarrheal and anti-nausea medications, along with rest and drinking plenty of fluids. IV fluids can treat severe cases of cyclosporiasis.

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When to Seek Medical Treatment

The biggest threat cyclosporiasis presents is dehydration. Many cases are unreported because people do not seek medical care for diarrhea and nausea. Adults should see a doctor for symptoms of dehydration such as headaches, rapid heartbeat, low blood pressure, and dizziness. A fever over 100ºF or bowel movements with black streaks or bloody mucus should prompt a medical visit. Monitor children closely at the first sign of diarrhea and consult a doctor if the symptom lasts more than two days; children become dehydrated faster than adults.

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Cyclosporiasis Fatigue

Cyclosporiasis can cause chronic fatigue that lasts for months after the initial infection resolves. People with cyclosporiasis fatigue feel tired continuously. The reason cyclosporiasis causes fatigue is not entirely clear. Some researchers and medical professionals believe it is due to how the parasite affects the small intestine. Cyclospora cayetanensis damages the epithelial cells lining the organ and also uses these cells to reproduce. Inflammation in the small intestine may interfere with nutrient absorption and upset the balance of beneficial bacteria in the intestines.

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The most effective strategies to prevent cyclosporiasis focus on places tha grow and harvest food. These farms should ensure proper hygiene of their workers and a clean environment. Consumers should always wash fresh produce, regardless of the source.

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Travel Precautions

Approximately one-third of cyclosporiasis cases in the United States are associated with international travel. Avoid raw or undercooked foods while traveling in tropical or subtropical regions. Do not use ice or water in open containers from restaurants or street vendors; most water treatment methods are not effective against Cyclospora cayetanensis and other protozoa species, so bottled water is the safest option. Travelers should practice caution when spending time in or near water in regions where cyclosporiasis is common.

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Challenges in Preventing Cyclosporiasis

Cyclosporiasis outbreaks are difficult to control and almost impossible to predict. Cyclospora cayetanensis is a protozoan with the ability to live for long periods in a dormant state. The parasite can complete its life cycle in approximately two weeks, but it is capable of living much longer. Cyclospora sporocysts can survive extreme heat, chlorine exposure, and many food sanitation processes.

Poor working conditions are the biggest challenge in preventing cyclosporiasis outbreaks. Agricultural workers in tropical and subtropical nations may lack access to bathroom facilities while they are working. The cyclospora parasite spreads rapidly when large numbers of people work in unsanitary conditions and handle food.

Cyclospora cayetanensisa, outbreaks, species, eradicating Dr_Microbe / Getty Images


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