Cyclosporiasis: An Annual Summer Parasitic Infection–How to Protect Yourself

Cyclospora has a life cycle both outside in the environment and inside its hosts.

A Cyclospora oocyst in stools. phiraporn takham/Shutterstock

Every summer, a parasite called Cyclospora cayetanensis is imported into the United States on fresh produce such as raspberries, leafy greens, and herbs.

The current multi-state cyclosporiasis outbreak has sickened thousands of Americans from New York to Texas, marking one of the largest surges of the intestinal illness in years. With concerns about rising infections, there are ways you can protect yourself against the parasite.

What Is Cyclosporiasis?

Cyclosporiasis is an intestinal illness caused by ingesting a microscopic, single-celled parasite, known as Cyclospora cayetanensis. It is a seasonal foodborne infection most commonly contracted by eating fresh, raw produce, such as leafy greens, berries, or herbs, that has been contaminated with trace amounts of infected human feces.

Symptoms are not immediate because the parasite needs time to develop and multiply in the intestines before causing illness.

Once inside your body, the parasite burrows into your intestinal lining to reproduce, damaging your gut and causing symptoms such as diarrhea, bloating, nausea, weight loss, and fatigue from nutrient loss.

After the parasites mature and reproduce in the intestines, fertilized eggs called oocysts are shed in a person’s stool and released into the environment, where they can eventually become infective and reach a new host.

How People Get Infected

Person-to-person transmission of cyclosporiasis is unlikely. Most infections occur through contaminated food or water.

“After being shed in stool by an infected person, the parasite takes several days to weeks before it becomes infectious to others,” Dr. Luis Marcos, an infectious disease specialist at Stony Brook Medicine in New York, told The Epoch Times.

Past multi-state outbreaks have been heavily associated with fresh herbs, bagged salad mixes, berries, and snow peas, according to the U.S. Food and Drug Administration.

Not everyone infected with Cyclospora will experience symptoms.

The hallmark symptom is frequent, explosive, watery diarrhea—often five to six times a day. Less commonly, people may experience vomiting, a low-grade fever, and body aches.

Norovirus vs. Cyclosporiasis

The two illnesses are easy to confuse but behave differently. Both norovirus and cyclosporiasis cause infections through the fecal-to-oral route and can cause gastrointestinal symptoms including diarrhea, nausea, and vomiting.

However, norovirus is caused by a virus that spreads directly from person to person. Its symptoms develop quickly, cause more severe illness lasting from one to two days, and often infect multiple household members. The opposite occurs with cyclosporiasis, which does not spread between people and has a slower onset of symptoms.

Diagnosis and Treatment

Diagnosis of cyclosporiasis is typically made through a stool test, but testing is usually only done if specifically requested by a healthcare provider. So if you suspect Cyclospora, ask directly.

Early evaluation is especially important if symptoms are severe or persistent, or if they occur in older adults, young children, pregnant women, or people with weakened immune systems, Marcos said.

“Prompt diagnosis and treatment can shorten the illness and help prevent complications,” he said.

Treatment mostly involves staying well hydrated to prevent dehydration caused by diarrhea.

Most people recover without medication—but if testing confirms Cyclospora infection, doctors may prescribe the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX), also known as Bactrim and Septra. “It is highly effective, and most people improve within a few days of starting therapy,” Marcos said. “The medication is generally well tolerated, although some people may experience nausea, vomiting, or mild skin rash.”

Left unaddressed, potential complications include profound dehydration from persistent diarrhea, malabsorption of nutrients, cholecystitis (gallbladder inflammation), and occasionally reactive arthritis or Guillain-Barré syndrome.

“If you develop diarrhea that lasts more than a few days—particularly during the summer months or after eating fresh produce, don’t assume it will simply go away,” he said.

How to Protect Yourself

Good hand hygiene is key to preventing food-related illnesses.

Wash your hands thoroughly with warm water and soap for at least 20 seconds, especially when preparing food or before eating. However, the best way to reduce your risk of cyclosporiasis is to wash fruits and vegetables thoroughly under running water before eating them, Marcos said.

Cyclosporiasis can be completely eradicated if food is fully cooked, but if eating food raw, there are several steps you can take to reduce risk:

1. Rinse all fruits and vegetables under clean, running water before eating, cutting, or cooking. Avoid soaking produce in a basin of water.
2. Remove any damaged or bruised parts of fruits and vegetables before eating.
3. Use a scrub to brush on firm foods such as melons and cucumbers.
4. Discard outer leaves of lettuce and wash leaves individually. For basil and cilantro, separate leaves and wash them thoroughly.
5. For onions, trim the root end, remove the outer layer, and wash thoroughly.
6. For hard-to-clean items such as raspberries, swish them in a mixture of three parts water to one part white vinegar for a minute, then drain and rinse well. Alternatively, consider using frozen berries.

Because the parasite forms a highly resilient shell, washing produce does not guarantee 100 percent removal, making cooking food above 158 degrees Fahrenheit the only surefire way to kill it.