Cyclosporiasis (cyclospora parasite)

Learn how cyclospora spreads, what symptoms it causes, when to seek care, and how the infection is diagnosed, treated and prevented.

Update Date: 08.08.2026

Overview
Symptoms
Causes
Risk factors
Complications
Prevention
Diagnosis
Treatment
Lifestyle and home remedies

Overview

Cyclosporiasis is an illness of the intestines. It is caused by a parasite called Cyclospora cayetanensis. The parasite gets into the body from food or water that has come into contact with human feces, also called stool. The parasite is unlikely to spread from person to person. You can get a cyclospora infection more than once.

Cyclosporiasis symptoms can last for weeks or longer. Symptoms can come back after you start to feel better.

People with typical immune systems often recover on their own, without prescription medicine. If you need medicine to clear out the infection, your care team may prescribe the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX). If you have a weakened immune system, you may need to take a higher dose or take the antibiotic for longer.

Symptoms

Cyclosporiasis symptoms often start about a week after you eat or drink a contaminated item, meaning an item that has come into contact with water or soil containing human stool.

Common cyclosporiasis symptoms can include:

  • Watery diarrhea.
  • Belly cramps.
  • Bloating.
  • Loss of appetite.
  • Feeling sick to the stomach, also called nausea.
  • Vomiting.
  • Feeling very tired, called fatigue.

Some people also have a mild fever.

Symptoms can last from days to weeks and may cause weight loss. Symptoms can improve and then get worse.

Other foodborne illnesses can cause similar symptoms. You may need testing to say for sure that the illness is cyclosporiasis.

When to see a doctor

People who have weakened immune systems may need medicine to treat cyclosporiasis. Also, people may need care if vomiting and diarrhea cause the body to lose too much fluid, called dehydration.

Talk to a healthcare professional if you have symptoms of dehydration, including:

  • Feeling very thirsty.
  • Dry mouth.
  • Urinating less than usual.
  • Loose stools that last more than one day in children and two days in adults.
  • Feeling weak, dizzy or lightheaded.

Get care right away for:

  • A high fever.
  • Not being able to drink enough fluids.
  • Serious belly or rectal pain.
  • Stools that are black, tarry or bloody or have pus.
  • New confusion, restlessness or unusual behavior.

Causes

Cyclosporiasis is caused by a parasite called Cyclospora cayetanensis. This species of the parasite infects only humans.

People get cyclosporiasis when they have food or water contaminated with the parasite.

  • Once in the gut, the parasite infects the lining of the intestines.
  • It reproduces and forms an egglike structure called an oocyst.
  • The oocyst passes out of the body in stool.

In the right environment, the oocyst matures into the stage of the parasite that can infect humans. Cyclospora oocysts cannot infect humans right away. The oocysts need to mature for 1 to 2 weeks.

It isn't always clear how cyclospora get into food and water. But experts think contamination can happen when crops come in contact with soil or water containing human stool or untreated sewage. People can help limit stool contamination of food by washing hands after using the toilet and cleaning and sanitizing areas where human stool may be present.

Risk factors

Anyone who eats or drinks items with cyclospora can get cyclosporiasis. This type of contamination can happen wherever food and water are exposed to human stool.

The risk of the illness goes up if you live in a place where cyclospora parasites are commonly found. Also, the risk is higher in places where outbreaks are happening.

In the United States, fresh fruits and vegetables are often the source of outbreaks. Spring and summer are when cyclosporiasis is most often reported.

The risk of a serious illness is higher for people with a weakened immune system.

Complications

Cyclosporiasis often gets better over weeks to months without causing other health issues, called complications.

One complication of cyclosporiasis may be mild to serious dehydration caused by long-term diarrhea and vomiting.

For people with a weakened immune system, cyclosporiasis also may lead to:

  • Inflammation or damage to the intestines.
  • Inflammation of the gallbladder and bile ducts.

Serious dehydration or complications may need to be treated in the hospital.

Prevention

Cyclosporiasis outbreaks in the United States are most often linked to fresh fruits and vegetables.

Past outbreaks of cyclosporiasis have been linked to:

  • Raspberries.
  • Pre-cut produce and bagged salad mixes.
  • Lettuce, basil and cilantro.
  • Snow peas.

The foods linked to outbreaks have been grown in the United States and imported from other places.

You can't see that an item is contaminated with the parasite. But there are ways to lower the risk of getting sick from contaminated food.

For cyclospora prevention:

  • During an outbreak, follow advice from your local health department. You may be advised to avoid some foods or watch for certain symptoms.
  • Take off the outside layers of produce before washing. This may mean throwing away the outer leaves on a head of cabbage or lettuce.
  • Cook fruits and vegetables. For fruits or vegetables that can be cooked, heating to an internal temperature of at least 158 degrees Fahrenheit (70 degrees Celsius) may help prevent illness. An example is cooking raspberries into a sauce or jam. For foods where you can't easily take an internal temperature, heat the food until it is hot throughout.

Also, follow basic food safety practices, including:

  • Wash hands well. Wash your hands with soap and water for at least 20 seconds. Do this after using the toilet, before eating, and before and after handling food.
  • Wash fruits and vegetables. Rinse fruits and vegetables under running water thoroughly before eating, peeling or using them in cooking. Scrub firm produce. Cut away any damaged areas before you use a fruit or vegetable. This doesn't guarantee your produce is free from cyclospora, but it can lower the risk. Don't use soap or bleach on food. If you eat bagged or pre-cut produce during an outbreak, wash it well too, even if it is labeled as pre-washed.
  • Wash kitchen utensils well. Wash cutting boards, knives and other utensils with hot, soapy water after contact with fruits and vegetables that aren't washed.

If you are at high risk of serious illness, talk to your healthcare team about what symptoms to watch for.

Diagnosis

Cyclosporiasis is diagnosed from a stool sample designed to find the parasite. Routine testing may not always identify cyclospora. You may have to give more than one stool sample before the parasite is identified or detected.

Your healthcare professional also may ask you about your symptoms and how long you've had them and about anything you may have eaten.

Treatment

Many people recover from cyclosporiasis without needing medical treatment. You may feel better over time with rest and fluids.

If you need medicine to clear out the infection, a healthcare professional may give you a prescription for trimethoprim-sulfamethoxazole (TMP-SMX). You may take this medicine for around 7 to 10 days. If you have a weakened immune system, you may need to take a higher dose or take the antibiotic for longer.

Lifestyle and home remedies

You often can manage cyclosporiasis symptoms with rest and fluids. Water or drinks with minerals, called rehydration solutions, may help replace fluids lost to vomiting or diarrhea. You may be able to eat a small meal or snack every few hours instead of larger meals.

Avoid spicy foods if they make your symptoms worse. Until you recover, limit drinks with caffeine, and avoid alcohol. Also avoid food and drink with a high amount of sugar, which can worsen diarrhea.

Ask a healthcare professional before taking medicine you can get without a prescription to stop diarrhea, bloating or upset stomach.

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