MSD Manual

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Richard D. Pearson

, MD, University of Virginia School of Medicine

Last full review/revision May 2020| Content last modified May 2020
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Cyclosporiasis is an infection of the small intestine caused by the parasite Cyclospora cayetanensis. The main symptoms are watery diarrhea with abdominal cramping and nausea.

Cyclosporiasis is most common in tropical and subtropical climates where sanitation is poor. Residents and travelers to endemic areas are at risk. In the United States, outbreaks of this infection have been attributed to imported fresh produce, such as raspberries, basil, snow peas, mesclun lettuce, and cilantro.

Symptoms of Cyclosporiasis

The primary symptom of cyclosporiasis is sudden, nonbloody, watery diarrhea, and nausea. Other symptoms include fever, abdominal cramps, vomiting, fatigue, and weight loss. Symptoms in people with a normal immune system last from a few days to a month or longer. Relapses may occur.

Diagnosis of Cyclosporiasis

  • Stool tests

To diagnose cyclosporiasis, a stool sample is examined under a microscope for Cyclospora eggs. Specialized techniques can be used to increase the chances of identifying the eggs. Molecular techniques are available in some reference laboratories to identify parasite DNA.

When stool examination does not reveal a cause of persistent diarrhea, doctors may use a flexible viewing tube (endoscope Endoscopy Endoscopy is an examination of internal structures using a flexible viewing tube (endoscope). Endoscopy can also be used to treat many disorders because doctors are able to pass instruments... read more ) to examine the upper part of digestive tract and obtain a sample of tissue (a biopsy) to be examined under a microscope and analyzed for parasite DNA.

Prevention of Cyclosporiasis

When outbreaks are reported, people should avoid eating potentially contaminated fruits or vegetables from the area. When traveling to tropical and subtropical areas where the infection is common, people should avoid eating uncooked foods, including salads and vegetables, and should avoid consuming potentially contaminated water and ice. Hand washing with soap and water is important. Drinking water that has been boiled is safe. Filtering water through a 0.1 or 0.4 micron filter can remove cysts of Cyclospora and other parasites, as well as bacteria that cause diseases.

Treatment of Cyclosporiasis

  • Trimethoprim/sulfamethoxazole (TMP/SMX)

Infected people who have symptoms can be treated with trimethoprim/sulfamethoxazole (TMP/SMX) taken by mouth.

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Human Immunodeficiency Virus (HIV) Infection
Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells. Untreated, it usually leads to acquired immunodeficiency syndrome (AIDS). Transmission of HIV requires contact with bodily fluid that contains the virus or cells infected with the virus. Which of the following is not a bodily fluid that commonly transmits HIV? 
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