Food Recall Resource

Cyclospora Infection: Overview, Symptoms, Treatment, Risk, Complications, and Prevention

The 2018 cyclospora outbreak linked to McDonald’s salad mix is apparently over. But you should still be careful. Read on to learn more.

Cyclospora infection or cyclosporiasis is uncommon in the US. An outbreak almost exclusively occurs from consuming imported fresh produce that contains mature parasite. In fact, most outbreaks have been linked to raspberries, basil, cilantro, snow peas, and mesclun lettuce.

The cyclospora parasite can only multiply within a person’s body. A direct person-to-person contact does not spread the infection. Thus, there is a negligible chance that you could get it from the infected food handlers.

Cyclosporiasis causes repeated bouts of watery diarrhea. However, it is rarely fatal. Antibiotics can effectively treat cyclospora infection. In most cases, the diagnosis is made based on the symptoms and laboratory tests are not routinely used for the diagnosis.

What is Cyclospora?

Cyclospora is a parasite that causes an intestinal illness called cyclosporiasis. Its scientific name is Cyclospora cayetanensis. It contains a single cell and one can only view it using a microscope.

The life cycle of cyclospora is more complicated than other microbes that cause foodborne illnesses. Only mature forms of the parasite can cause an illness. Stools from an infected person contain immature parasites, which are not able to cause the illness.

The immature parasites first need to grow in the environment before they infect another person. This may take days or even weeks. Thus, person-to-person transmission of the illness is quite unlikely.

Cyclospora Symptoms

Most cyclospora symptoms are not specific. Many other foodborne illnesses can cause similar symptoms. The symptoms are more severe in countries like the US where the infection is not common.

The incubation period of cyclospora infection is about a week. This means that a person usually experiences the symptoms within a week after exposure to the parasite. However, some people who have the parasite in their body may not experience any symptoms at all.

In other people, the symptoms can include:

  • A buildup of gas in the stomach
  • Fever between 98.7°F and 100.4°F
  • Flu-like symptoms such as a headache and body aches
  • Nausea
  • Reduced appetite
  • Stomach cramps
  • Watery diarrhea, which is sometimes explosive
  • Weakness and a general feeling of illness
  • Weight loss

The symptoms can last from a few days to several weeks if you fail to receive treatment. Most notably, some people may feel fine after a few days and become ill again. This is called a relapse.

Your body cannot protect itself from a second infection after an initial illness. Thus, relapses are common.

Cyclospora Treatment: Know Your Options

Most people with the infection recover within weeks without any specific treatment. Drinking plenty of fluids and maintaining hydration is enough.

Nonetheless, those with weakened immune systems may have long-lasting diarrhea.

A combination antibiotic called trimethoprim-sulfamethoxazole (TMP/SMX) is effective in treating the illness. Most people recover with a 7- to 10-day course of TMP/SMX. People with compromised immune systems need higher doses for a longer duration.

The brands of trimethoprim-sulfamethoxazole available in the US are Bactrim, Septra and Cotrim.

If you are allergic to TMP/SMX, the doctor may prescribe another antibiotic, ciprofloxacin or nitazoxanide.

Most importantly, you should not take anti-diarrheal medicine without consulting a health care provider.

Cyclospora Complications

Prolonged diarrhea can cause dehydration in some people. This is more likely to happen if a person does not consume enough fluids.

Watch out for the following warning signs of dehydration. If you have any of these, seek medical help right away.

  • Sunken eyes
  • Dry mouth and tongue due to reduced production of saliva
  • Inadequate production of tears
  • Decreased frequency or volume of urine

In rare cases, long-lasting cyclospora infection may lead to Guillain-Barre Syndrome (GBS) and Reiter syndrome. However, limited information on this is available now.

GBS can cause muscle weakness and in some cases, paralysis. Reiter syndrome, also known as reactive arthritis, causes pain and swelling in the joints.

Who is at Risk of Cyclospora Infection?

Anyone who consumes contaminated food or water can get ill. However, the risk is higher among individuals who have traveled to the countries where the illness is common.

Besides, having weakened immune systems also significantly increases the risk of being infected.

Other high-risk groups include kids, elderly, and those with HIV/AIDS.

How Can You Prevent Cyclospora Infections?

The best way to prevent cyclospora infections is to avoid consuming contaminated food and water.

Thoroughly wash fruits and vegetables before eating. Do not swallow recreational water. Even pool water treated with chlorine may contain the parasite. Avoid swimming if you are ill or have just recovered.

Cyclosporiasis occurs frequently in tropical and subtropical regions. Both long-term and short-term travels may become infected.

If you are traveling to a country, where the illness is common,

  • Drink only bottled or boiled water.
  • Wash your hands after using the toilet.
  • Eat only steaming hot foods.
  • Wash your hands with soap and water before preparing or eating food.
  • Avoid eating fruits and vegetables that you did not wash or peel.
  • Do not eat ice as the water used for making the ice may contain the parasite.
  • Thoroughly wash cutting boards, dishes, utensils, and countertops that have been exposed to raw meat, poultry, seafood products, raw fruits, and vegetables.
  • Store cut, peeled, or cooked fruits and vegetables in the refrigerator within 2 hours. Keep fruits and vegetables separate from raw meat, poultry, and seafood.

Find the food and water precautions for travelers here.

Top 10 Interesting Facts about Cyclospora Infection

  1. C. cayetanensis was first discovered in 1979 in Papua New Guinea.
  2. Cyclospora infection is not life-threatening even when a person does not receive any treatment. But severe dehydration from excessive loss of fluids due to frequent diarrhea can be serious.
  3. Currently, no vaccine is available. Besides, washing fresh produce may not entirely remove the parasite.
  4. Other than humans, cyclospora parasite may be present in birds. Nonetheless, there have been no reports of anyone getting ill from exposure to the birds.
  5. Fresh stools from an infected person do not spread the illness.
  6. Most disinfectants are ineffective against the thick-walled forms of the parasite, which are called oocysts. Only a few oocysts are capable of spreading the illness. Even worse, they can survive for long durations in cool, moist environments.
  7. In the US, most cyclospora infections occur between May and July. It seems that the risk varies with season.
  8. Unlike imported fresh produce, frozen and canned produce carry a low risk of infection.
  9. Most laboratories do not include tests to determine the presence of cyclospora in their routine stool analysis. Thus, you have to request a separate test if you think you have the parasite in your intestines.
  10. The immature parasites take 7 to 15 days in the environment at 73.4°F to 44.6°F to become infectious.


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