Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. People can become infected with Cyclospora by consuming food or water contaminated with the parasite. People living or traveling in countries where cyclosporiasis is endemic may be at increased risk for infection.

Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. The parasite can infect people when they ingest something—such as food or water—that was contaminated with feces (stool). CDC scientists and partners are using Advanced Molecular Detection (AMD) methods to develop DNA fingerprinting to distinguish among same or similar C. cayetanensis that cause cyclosporiasis. These tools could help link cases to each other and to particular food products, and help public health officials investigate and prevent further cases and outbreaks of Cyclospora infection.

Key Facts

• Cyclospora cayetanensis is a microscopic parasite that causes an intestinal infection called cyclosporiasis.
• In the United States, foodborne outbreaks of cyclosporiasis have been linked to various types of imported fresh produce.
• Cyclosporiasis has been reported in many countries but is most common in tropical and subtropical areas.
• The majority of U.S. cases occur in warmer months. Outbreaks have been identified nearly every year since the mid-1990s.

Feeling Sick?

A person with cyclosporiasis may begin to feel sick about 7 days after eating contaminated food. Symptoms may include watery diarrhea (most common), loss of appetite, weight loss, cramping, bloating, increased gas, nausea, and fatigue. Since these may be similar to those of other intestinal illnesses, cyclosporiasis can only be diagnosed by a doctor.

Food Safety Importance

To prevent cyclosporiasis, try to avoid food or water that may have been contaminated with stool. If traveling, follow safe food and water habits. At home, wash all fruits and vegetables thoroughly under running water before eating, cutting, or cooking. Fruits and vegetables that are labeled “prewashed” do not need to be washed again.

Troublesome Parasite

Cyclospora cayetanensis is a parasite composed of one cell, too small to be seen without a microscope. This parasite causes an intestinal infection called cyclosporiasis.

Developing Detection Tools

AMD methods help CDC and other agencies distinguish different infections or contaminations of food by Cyclospora parasites based on their DNA. These tools could help link cases of cyclosporiasis to each other and to particular types of food, and help public health officials investigate and prevent cases and outbreaks of cyclosporiasis.

Prevention Tips

• Travelers to cyclosporiasis-endemic areas (such as tropical and subtropical regions) should be aware that treatment of water or food by routine chemical disinfection or sanitizing methods is unlikely to kill the Cyclospora parasite.
• See your healthcare provider if you think you have cyclosporiasis. A specific test for the parasite is required to diagnose the infection.

It is also important to follow these food safety precautions:

• Wash your hands with soap and water before and after handling or preparing fruits and vegetables.
• Wash all surfaces with soap and water between preparing raw meat, poultry, and seafood products and preparing fruits and vegetables that will not be cooked.
• Scrub firm fruits and vegetables, such as melons and cucumbers, with a clean produce brush. Cut away any damaged or bruised areas on fruits and vegetables before preparing and eating.
• Refrigerate cut, peeled, or cooked fruits and vegetables as soon as possible, or within 2 hours. Store fruits and vegetables away from raw meat, poultry, and seafood.

Cyclospora cayetanensis is a parasite that is so small it can only be seen under a microscope. When people eat food or drink water that’s contaminated with Cyclospora, they can get an intestinal illness called cyclosporiasis.

Cyclospora is generally transmitted when infected feces contaminate food or water. It’s unlikely to be transmitted directly from person to person because the Cyclospora parasite needs time (days to weeks) after being passed in a bowel movement to become infectious for another person.

Who Is at Risk?

People living or traveling in countries where cyclosporiasis is common, including certain tropical or subtropical regions of the world, may be at increased risk for infection. However, people living in other areas can become infected with Cyclospora by consuming food or water that has been contaminated with the parasite.

What Are the Symptoms?

The time between becoming infected and becoming sick is usually about one week. Cyclospora infects the small intestine (bowel) and usually causes watery diarrhea, with frequent, sometimes explosive, bowel movements. Other common symptoms include loss of appetite, weight loss, stomach cramps/pain, bloating, increased gas, nausea, and fatigue. People may also experience vomiting, body aches, headache, low-grade fever, and other flu-like symptoms. Some people who are infected with Cyclospora do not have any symptoms. If not treated, the illness may last from a few days to a month or longer. Symptoms may seem to go away and then return one or more times (relapse). It’s common to feel very tired.

What Foods Have Been Linked to U.S. Outbreaks of Cyclosporiasis?

Past cyclosporiasis outbreaks in the U.S. have been linked to raspberries, basil, cilantro, snow peas and mesclun lettuce. Although it’s unknown exactly how food and water become infected with Cyclospora, people should be aware that rinsing or washing food is not likely to remove it.

What Do Restaurants and Retailers Need to Do?

Based on current information available Cyclospora may be resistant to routine chemical disinfection methods such as those using chlorine. However, restaurants and retailers should still follow basic food safety practices:

• Retailers, restaurants, and other food service operators should always practice safe food handling and preparation measures. It is recommended that they wash and sanitize utensils, and surfaces before and after handling food. Wash and sanitize display cases and refrigerators where potentially contaminated products were stored.
• Wash and sanitize cutting boards, surfaces, and utensils used to prepare, serve, or store potentially contaminated products.
• Wash hands with warm water and soap following the cleaning and sanitation process.
• Regular frequent cleaning and sanitizing of food contact surfaces and utensils used in food preparation may help to minimize the likelihood of cross-contamination.

What do Consumers Need to Do?

Consumers should follow these steps:

• Wash the inside walls and shelves of the refrigerator, cutting boards and countertops; then sanitize them with a solution of one tablespoon of chlorine bleach to one gallon of hot water; dry with a clean cloth or paper towel that has not been previously used.
• Wash hands with warm water and soap for at least 20 seconds before and after handling food.
• Wipe up spills in the refrigerator immediately and clean the refrigerator regularly.
• Always wash hands with hot, soapy water following the cleaning and sanitization process.
• Persons who think they might have become ill from eating potentially contaminated foods should consult their health care provider.

Who Should Be Contacted?

Contact your healthcare provider if you have diarrhea that lasts for more than three days.

Fast Facts for Farmers:

• Cyclosporiasis is an intestinal illness caused by the parasite Cyclospora cayetanensis (C. cayetanensis), which only occurs in humans, and the most common symptom is diarrhea.
• Infected people shed the parasite in their feces.
• When the parasite is found in water or food, it means that the water or food has been contaminated with human feces.
• Other people may become sick by ingesting water or food contaminated with the parasite.
• Good hygiene (including proper handwashing) is a critical component of ensuring the safety of fresh produce, but by itself it may not be enough to prevent infected employees from contaminating fresh produce.
• The FSMA Produce Safety Rule requires that personnel on farms use hygienic practices (§ 112.32) and that ill employees are excluded from handling fresh produce and food contact surfaces (§ 112.31).

What is Cyclospora cayetanensis?

C. cayetanensis is a human parasite, which means it must live inside a human host to survive and multiply. The parasite can cause an infection, called cyclosporiasis. A person may become infected after ingesting food or water contaminated with the parasite. Infected people, even if showing no symptoms of infection, may shed the parasite in their feces, which can contaminate food and water, leading to the infection of other people. Cyclosporiasis outbreaks have been associated with the consumption of fresh fruits and vegetables around the world, including in the U.S.

What are the symptoms of cyclosporiasis?

Most people infected with C. cayetanensis develop diarrhea, with frequent, sometimes explosive, bowel movements. Other symptoms may include vomiting, body aches, headache, fever, other flu-like symptoms, loss of appetite, weight loss, stomach cramps/pain, bloating, increased gas, nausea, and fatigue.

Symptoms may seem to go away and then return one or more times (relapse). If not treated, the illness may last from a few days to a month or longer. Some people who are infected with C. cayetanensis do not show any symptoms.The infection is treated with antibiotics, and most infected people respond quickly to treatment.

Where is this parasite found?

• Cyclosporiasis is endemic or commonly found among the population in certain countries/regions.
• Since the infection occurs only in humans, the parasite originates from the feces of ill people.
• The parasite may also be found in water and food, if it has been contaminated by human feces.
• No non-human host (animals) for this parasite has been identified.
• C. cayetanensis is not limited to imported foods. In July, FDA found the first confirmed evidence of the presence of C. cayetanensis in domestic produce when two cilantro samples tested positive for the parasite.

What else do we know about this parasite?

• Although clinical testing for the parasite in human feces has been available since the 1970s, FDA recently improved the method for the detection of this parasite on some fresh fruits and vegetables.
• The parasite needs to spend some time in the environment to later cause cyclosporiasis, therefore, C. cayetanensis is unlikely to be transmitted directly from person-to-person and still cause illness.
• The parasite needs specific environmental conditions to become infectious. Under experimental conditions, a combination of time and temperature (temperatures from 73° to 77°F during 7 – 15 days) were required for C. cayetanensis to become infectious.
• Although chlorine and other antimicrobial washes are effective at reducing harmful populations of bacteria and viruses, they are not as effective on C. cayetanensis. In countries/regions where cyclosporiasis is endemic, microfiltration, ozone, or UV treatments may be effective at decreasing populations of C. cayetanensis in irrigation waters.

What can I do to reduce the likelihood of contaminating fresh produce with C. cayetanensis?

Controlling sources of contamination in the field, in the packinghouse, and from farm workers is key to preventing illnesses. Farms can do the following to minimize the chance of contaminating fresh produce with C. cayetanensis:

• Train farm workers on how to properly use toilet facilities provided by the farm, including the sanitary disposal of toilet paper.
• Consider the varying cultural practices of farm workers when providing training on produce safety.
• If utilizing a contractor for cleaning and sanitizing the portable toilets, consider using reputable companies that dispose of human waste into an adequate sewage system or through other adequate means. Municipal wastewater treatment incorporates disinfection processes designed to kill or inactivate C. cayetanensis.

What are some steps that farms are required to take by the FSMA Produce Safety Rule?

Farms covered by the Produce Safety Rule must do the following:

• Train farm workers who handle produce or food contact surfaces on how to properly wash their hands with soap and running water, properly dry hands, and properly dispose of the paper towels. Free videos and training materials exist in multiple languages online.
• Make sure toilets and handwashing stations are maintained, cleaned, and emptied in a way that prevents human waste and/or gray water from contaminating fresh produce, food contact surfaces, and adjacent areas.
• Train farm workers to self-report applicable symptoms and illnesses to the appropriate responsible person, and don’t allow ill farm workers to handle fresh produce or touch food contact surfaces.

What happens if infected farm workers handle produce?

Workers infected with C. cayetanensis can transmit the parasite to fresh produce, which can cause people to get sick if the contaminated produce is consumed. Therefore, it is essential that ill employees be excluded from handling fresh produce and food contact surfaces. If you have reason to suspect a cyclosporiasis infection, consider working with your public health agency. Identifying and treating the infection is essential to preventing new infections, amongst consumers or farm workers, through contaminated food and water.

People become infected with Cyclospora by ingesting sporulated oocysts, which are the infective form of the parasite. This most commonly occurs when food or water contaminated with feces is consumed. An infected person sheds unsporulated (immature, non-infective) Cyclospora oocysts in the feces. The oocysts are thought to require at least 1–2 weeks in favorable environmental conditions to sporulate and become infective. Therefore, direct person-to-person transmission is unlikely, as is transmission via ingestion of newly contaminated food or water.

Geographic Distribution

Cyclosporiasis occurs in many countries, but it seems to be most common in tropical and subtropical regions. In areas where cyclosporiasis has been studied, the risk for infection is seasonal. However, no consistent pattern has been identified regarding the time of year or the environmental conditions, such as temperature or rainfall.

In the United States, foodborne outbreaks of cyclosporiasis have been linked to various types of imported fresh produce, such as raspberries, basil, snow peas, mesclun lettuce, and cilantro; no commercially frozen or canned produce has been implicated to date.

U.S. cases of infection also have occurred in persons who traveled to Cyclospora-endemic areas. To reduce the risk for infection, travelers should take precautions, such as those recommended in CDC’s Health Information for International Travel (Yellow Book). Travelers should be aware that treatment of water or food by routine chemical disinfection or sanitizing methods is unlikely to kill Cyclospora oocysts.

Causal Agents

Cyclospora cayetanensis is a coccidian protozoan. It appears that all human cases are caused by this species; no animal reservoirs for C. cayetanensis have been identified.

Life Cycle

When freshly passed in stools, the oocyst is not infective 1 (thus, direct fecal-oral transmission cannot occur; this differentiates Cyclospora from another important coccidian parasite, Cryptosporidium). In the environment 2 , sporulation occurs after days or weeks at temperatures between 22°C to 32°C, resulting in division of the sporont into two sporocysts, each containing two elongate sporozoites 3 . The sporulated oocysts can contaminate fresh produce and water 4 which are then ingested 5 . The oocysts excyst in the gastrointestinal tract, freeing the sporozoites, which invade the epithelial cells of the small intestine 6 . Inside the cells they undergo asexual multiplication into type I and type II meronts. Merozoites from type I meronts likely remain in the asexual cycle, while merozoites from type II meronts undergo sexual development into macrogametocytes and microgametocytes upon invasion of another host cell. Fertilization occurs, and the zygote develops to an oocyst which is released from the host cell and shed in the stool 7 . Several aspects of intracellular replication and development are still unknown, and the potential mechanisms of contamination of food and water are still under investigation.

Life cycle image and information courtesy of DPDx.

Symptoms of cyclosporiasis begin an average of 7 days (range, 2 days to ≥2 weeks) after ingestion of sporulated oocysts (the infective form of the parasite).

Symptoms of cyclosporiasis may include the following:

• Watery diarrhea (most common)
• Loss of appetite
• Weight loss
• Cramping
• Bloating
• Increased gas
• Nausea
• Fatigue

Other symptoms that may occur but are less common include the following:

• Vomiting
• Low-grade fever

If a person ill from cyclosporiasis is not treated, symptoms can persist for several weeks to a month or more. Some symptoms, such as diarrhea, can return; and some symptoms, such as fatigue, may continue after the gastrointestinal symptoms have gone away. The infection usually is not life threatening. Some infected persons do not have any symptoms, particularly persons from areas where cyclosporiasis is endemic, such as tropical and subtropical regions.

Cyclospora infection is diagnosed by examining stool specimens. Diagnosis can be difficult in part because even patients who are symptomatic might not shed enough oocysts in their stool to be readily detectable by laboratory examinations. Therefore, patients might need to submit several specimens collected on different days. Identification of the parasite requires special laboratory tests that are not routinely done when stool is tested for parasites. Therefore, if indicated, health care providers should specifically request testing for Cyclospora.

Trimethoprim/sulfamethoxazole (TMP/SMX), sold under the trade names Bactrim*, Septra*, and Cotrim*, is the usual therapy for Cyclospora infection. No highly effective alternative antibiotic regimen has been identified yet for patients who do not respond to the standard treatment or have a sulfa allergy.

Most people who have healthy immune systems will recover without treatment. If not treated, the illness may last for a few days to a month or longer. Symptoms may seem to go away and then return one or more times (relapse). Anti-diarrheal medicine may help reduce diarrhea, but a health care provider should be consulted before such medicine is taken. People who are in poor health or who have weakened immune systems may be at higher risk for severe or prolonged illness.

* Use of trade names is for identification only and does not imply endorsement by the Public Health Service or by the U.S. Department of Health and Human Services.

On the basis of the currently available information, avoiding food or water that may have been contaminated with feces is the best way to prevent cyclosporiasis. Travelers to cyclosporiasis-endemic areas (such as tropical and subtropical regions) should be aware that treatment of water or food by routine chemical disinfection or sanitizing methods is unlikely to kill Cyclospora. No vaccine for cyclosporiasis is available.

Consumers and retailers should always follow safe fruit and vegetable handling recommendations:

Wash: Wash hands with soap and warm water before and after handling or preparing fruits and vegetables. Wash cutting boards, dishes, utensils, and counter tops with soap and hot water between the preparation of raw meat, poultry, and seafood products and the preparation of fruits and vegetables that will not be cooked.

Prepare: Wash all fruits and vegetables thoroughly under running water before eating, cutting, or cooking. Fruits and vegetables that are labeled “prewashed” do not need to be washed again at home. Scrub firm fruits and vegetables, such as melons and cucumbers, with a clean produce brush. Cut away any damaged or bruised areas on fruits and vegetables before preparing and eating.

Store: Refrigerate cut, peeled, or cooked fruits and vegetables as soon as possible, or within 2 hours. Store fruits and vegetables away from raw meat, poultry, and seafood.

What is Cyclospora?

Cyclospora cayetanensis is a parasite composed of one cell, too small to be seen without a microscope. This parasite causes an intestinal infection called cyclosporiasis.

How is Cyclospora spread?

Cyclospora is spread by people ingesting something—such as food or water—that was contaminated with feces (stool). Cyclospora needs time (typically, at least 1–2 weeks) after being passed in a bowel movement to become infectious for another person. Therefore, it is unlikely that Cyclospora is passed directly from one person to another.

Who is at risk for Cyclospora infection?

People living or traveling in tropical or subtropical regions of the world may be at increased risk for infection because cyclosporiasis is endemic (found) in some countries in these zones. In the United States, foodborne outbreaks of cyclosporiasis have been linked to various types of imported fresh produce. People can get infected with Cyclospora more than once.

What are the symptoms of Cyclospora infection?

The time between becoming infected and becoming sick is usually about 1 week. Cyclospora infects the small intestine (bowel) and usually causes watery diarrhea, with frequent, sometimes explosive, bowel movements. Other common symptoms include loss of appetite, weight loss, stomach cramps/pain, bloating, increased gas, nausea, and fatigue. Vomiting, body aches, headache, fever, and other flu-like symptoms may be noted. Some people who are infected with Cyclospora do not have any symptoms.

How long can the symptoms last?

If not treated, the illness may last from a few days to a month or longer. Symptoms may seem to go away and then return one or more times (relapse). It’s common to feel very tired.

What should I do if I think I might be infected with Cyclospora?

See your health care provider.

How is Cyclospora infection diagnosed?

Your health care provider will ask you to submit stool specimens to see if you are infected. You might be asked to submit more than one specimen from different days. Identification of this parasite in stool requires special laboratory tests that are not routinely done. Therefore, if indicated, your health care provider should specifically request testing for Cyclospora. In addition, your health care provider might have your stool checked for other organisms that can cause similar symptoms.

How is Cyclospora infection treated?

The recommended treatment is a combination of two antibiotics, trimethoprim-sulfamethoxazole, also known as Bactrim*, Septra*, or Cotrim*. People who have diarrhea should also rest and drink plenty of fluids.

I am allergic to sulfa drugs; is there another drug I can take?

No highly effective alternative drugs have been identified yet for people with Cyclospora infection who are unable to take sulfa drugs. See your health care provider to discuss potential options.

How is Cyclospora infection prevented?

Avoiding food or water that might have been contaminated with stool may help prevent Cyclospora infection.

Consumers and retailers should always follow safe fruit and vegetable handling recommendations:

Wash: Wash hands with soap and warm water before and after handling or preparing fruits and vegetables. Wash cutting boards, dishes, utensils, and counter tops with soap and hot water between the preparation of raw meat, poultry, and seafood products and the preparation of fruits and vegetables that will not be cooked.

Prepare: Wash all fruits and vegetables thoroughly under running water before eating, cutting, or cooking. Fruits and vegetables that are labeled “prewashed” do not need to be washed again at home. Scrub firm fruits and vegetables, such as melons and cucumbers, with a clean produce brush. Cut away any damaged or bruised areas on fruits and vegetables before preparing and eating.

Store: Refrigerate cut, peeled, or cooked fruits and vegetables as soon as possible, or within 2 hours. Store fruits and vegetables away from raw meat, poultry, and seafood.

* Use of trade names is for identification only and does not imply endorsement by the Public Health Service or by the U.S. Department of Health and Human Services.