Cyclosporiasis: What You Need to Know About This Summer's Foodborne Illness

Every summer, health departments across the United States see an increase in cases of cyclosporiasis, an intestinal infection caused by the microscopic parasite Cyclospora cayetanensis. Although many people have never heard of it, it causes thousands of illnesses each year, particularly during the warmer months. This summer, the CDC and FDA are investigating one of the largest U.S. outbreaks of cyclosporiasis to date. Multiple states have reported cases, with some illnesses linked to contaminated imported produce. Cases have also been reported in Maryland and Virginia, making this especially relevant for residents of Rockville, Montgomery County, and the greater Washington, DC metro area. Fortunately, cyclosporiasis is treatable — but recognizing the symptoms and seeking medical care when appropriate are key.

What Is Cyclosporiasis?

Cyclosporiasis is an intestinal infection spread by eating food or drinking water contaminated with Cyclospora. In the United States, outbreaks have most commonly been linked to fresh produce such as leafy greens, herbs, berries, and other fruits and vegetables eaten raw.

Unlike many other intestinal infections, Cyclospora is not usually spread directly from person to person. The parasite passed in stool must mature in the environment for at least one to two weeks before it becomes infectious, making household transmission unlikely.

Who Is at Risk?

Anyone can become infected, but the illness may be more severe in:

• Young children and older adults
• People with weakened immune systems, such as those with HIV/AIDS, organ transplants, or taking immunosuppressive medications
• Travelers to tropical or subtropical regions where the parasite is more common

What Are the Symptoms?

Some people have no symptoms. For those who become ill, symptoms usually begin about one week after eating contaminated food, although they can appear anywhere from 2 days to more than 2 weeks later.

Common symptoms include:

• Watery diarrhea
• Loss of appetite
• Fatigue
• Abdominal cramping, bloating, and gas
• Nausea
• Low-grade fever

A hallmark of cyclosporiasis is that symptoms often come and go. Without treatment, the illness typically lasts 2–4 weeks, but it can persist even longer.

How Is It Diagnosed?

Routine stool tests often do not check for Cyclospora. If your doctor suspects the infection, specialized stool testing, such as PCR or other specific laboratory tests, may be needed. Because the parasite is shed intermittently, more than one stool sample may be required.

How Is It Treated?

The recommended treatment is trimethoprim-sulfamethoxazole (Bactrim® or Septra®), usually taken twice daily for seven days. Most people begin to feel better within one to two days of starting treatment.

People with a sulfa allergy may require alternative treatment, although available options are generally less effective.

How Can You Protect Yourself?

Prevention of cyclosporiasis is challenging because the Cyclospora parasite is unusually tough. Its oocysts (eggs) can survive for weeks to months on produce and in water, and they are resistant to most common disinfectants — including the chlorine concentrations used in standard water treatment and commercial produce washing. That means you cannot simply rely on a quick rinse or a produce wash spray to make food safe.

At the Grocery Store and Farmers' Market

Know the high-risk foods. U.S. outbreaks have been linked specifically to fresh cilantro, basil, raspberries, mixed salad greens, and snow peas. Be especially mindful of these items during the May–August peak season.

Check for recalls. During the summer months, the FDA frequently issues recalls and alerts related to Cyclospora contamination. Check the FDA website or sign up for recall alerts.

In the Kitchen

Wash all fresh produce thoroughly under clean, running water before eating, cutting, or cooking — even if you plan to peel it. While washing may not eliminate all oocysts, it can reduce the amount of contamination.

Scrub firm produce (like cucumbers and melons) with a clean brush under running water.

Cook when possible. Cyclospora oocysts are killed by heat. Cooking produce to pasteurization temperatures eliminates the risk entirely. During peak season, consider cooking herbs like basil and cilantro into sauces rather than using them raw.

Understand the limits of produce washes. Commercial produce washes, vinegar rinses, and diluted bleach solutions have not been shown to reliably kill Cyclospora. Do not assume these products make raw produce completely safe.

When Traveling to Tropical or Subtropical Areas

• Drink only boiled or bottled water. Standard water chlorination does not kill Cyclospora oocysts.
• Avoid raw fruits and vegetables that you cannot peel yourself.
• Avoid ice in drinks unless you know it was made from purified water.
• Ultraviolet (UV) water purification devices are effective against Cyclospora and are a good option for travelers.
• Water filters with a pore size of 1 micron or smaller can physically remove the oocysts from drinking water.

When Should You See Your Doctor?

Contact your healthcare provider if you have:

• Diarrhea lasting more than a few days
• Diarrhea that improves and then returns
• Significant weight loss or signs of dehydration
• Persistent diarrhea after international travel
• Prolonged diarrhea after eating fresh produce during the spring or summer

Be sure to mention any recent travel, restaurant meals, or fresh produce you have eaten. If routine stool tests are negative but symptoms continue, ask whether testing for Cyclospora should be included. If you live in Rockville or elsewhere in Montgomery County, your primary care physician can order the right stool testing and start treatment quickly.

The Bottom Line

Cyclosporiasis is an underrecognized but treatable cause of prolonged diarrhea, especially during the warmer months. With the current U.S. outbreak, it's important not to dismiss persistent or recurring diarrhea as simply a "stomach bug." Early diagnosis and appropriate treatment can help you recover more quickly and prevent unnecessary illness.

Concerned About Persistent Digestive Symptoms?

If you're experiencing prolonged or recurring diarrhea — especially after recent travel or after eating fresh produce this summer — schedule a visit with Aurora Primary Care. As a direct primary care practice serving Rockville, Montgomery County, and the greater DC area, we can help you get the right testing and treatment quickly, without a long wait for an appointment.

Frequently Asked Questions

Q1. What is cyclosporiasis?

Ans: Cyclosporiasis is an intestinal infection caused by the microscopic parasite Cyclospora cayetanensis, spread by eating food or drinking water contaminated with the parasite — most often fresh produce such as leafy greens, herbs, and berries eaten raw.

Q2. Is cyclosporiasis contagious from person to person?

Ans: Not usually. The parasite passed in stool must mature in the environment for one to two weeks before it becomes infectious, so household transmission from one person to another is unlikely.

Q3. What are the most common symptoms of cyclosporiasis?

Ans: The most common symptoms are watery diarrhea, loss of appetite, fatigue, abdominal cramping and bloating, nausea, and low-grade fever. A hallmark of the illness is that symptoms often come and go rather than staying constant.

Q4. How long does cyclosporiasis last if it isn't treated?

Ans: Without treatment, cyclosporiasis typically lasts 2 to 4 weeks, but it can persist even longer in some people.

Q5. How is cyclosporiasis treated?

Ans: The recommended treatment is trimethoprim-sulfamethoxazole (Bactrim® or Septra®), usually taken twice daily for seven days. Most people begin to feel better within one to two days of starting treatment. People with a sulfa allergy may need an alternative, though options are generally less effective.

Q6. When should I see a doctor about possible cyclosporiasis?

Ans: Contact your healthcare provider if diarrhea lasts more than a few days, improves and then returns, is accompanied by significant weight loss or dehydration, or follows recent international travel or eating fresh produce during spring or summer.