Explosive diarrhea? Here's what to know about Cyclospora

Is it bacteria? Is it a virus? It’s actually neither.

Cyclospora is a microscopic parasite that causes an intestinal illness called cyclosporiasis. It spreads when someone consumes food or water contaminated with human feces.

Cyclospora cayetanensis is most commonly linked to fresh produce that is typically eaten raw, including fruits, leafy greens and herbs. Past outbreaks in the U.S. have been tied to basil, cilantro, berries and parsley.

Contamination can happen in several ways and usually occurs before food ever reaches consumers. Cyclospora can be introduced if produce is irrigated or washed with contaminated water, or if a food handler contaminates produce through poor hygiene.

Fresh produce is washed during processing to remove dirt and debris, but it is not sterilized. Unlike foods cooked at high temperatures, fresh fruits and vegetables do not undergo treatments that reliably kill parasites. Cyclospora is not visible to the human eye and can cling to crevices in produce, making it difficult to remove through washing alone.

Unlike the viruses behind the stomach flu or norovirus, Cyclospora is not typically spread directly from person to person.

Cyclospora cayetanensis needs time to mature after it is shed in human feces. If that waste contaminates produce or water, the parasite must spend days or weeks in the environment before it becomes infectious — a process known as sporulation.

As a result, someone with Cyclospora is highly unlikely to pass the illness directly to someone else through everyday contact.

For most otherwise healthy people, a Cyclospora infection is not life-threatening and remains uncommon. However, at least 20 Americans have been hospitalized since May 1, 2026, according to the Centers for Disease Control and Prevention’s latest multistate investigation.

North Carolina has reported at least 110 Cyclospora cases since May 1, 2026, with no hospitalizations reported as of July 6, 2026.

Without treatment, symptoms can last for days or even weeks. Some patients infected with Cyclospora during a 2024 outbreak involving more than 130 cases in Wake County told WRAL they experienced diarrhea that lasted for a month.

Severe diarrhea can also lead to dehydration.

People with weakened immune systems, older adults and others who are more vulnerable to dehydration may be at greater risk for severe illness.

The only way to confirm a Cyclospora infection is through a stool test. Depending on the laboratory and the tests ordered, your health care provider may need to specifically request testing for Cyclospora, as it is not included in many routine stool tests in the U.S.

A single negative test may not always rule out a Cyclospora infection. Patients may shed the parasite intermittently, so one sample may miss it. In some cases, providers may request multiple stool samples to improve the chances of detection.

North Carolina Department of Health and Human Services officials report cases have been seen in patients of all ages.

Cyclospora symptoms can look similar to many other intestinal illnesses, making it difficult to diagnose based on symptoms alone. Symptoms typically begin about one week after consuming contaminated food or water, but they can appear anywhere from two to 14 days later, or longer.

The most common symptom is frequent, watery diarrhea, which is often described as severe or explosive.

Other symptoms may include:

• Severe abdominal cramping

• Bloating and increased gas

• Loss of appetite

• Nausea

• Body aches

• Fatigue

• Low-grade fever

• Weight loss in some cases

Cyclospora is considered an uncommon foodborne illness in the U.S., though the U.S. Food and Drug Administration warns that people traveling to tropical or subtropical regions of the world may be at higher risk of infection.

Cyclospora cases are reported every year in the U.S., with increases commonly seen during the spring and summer months. The CDC considers “Cyclospora season” to run from May 1 through Aug. 31, when imports of fresh produce commonly linked to the parasite are at their highest.

Even when dozens or hundreds of people get sick, health investigators may not always identify the contaminated food or beverage associated with a cluster of Cyclospora cases.

One reason is the parasite’s lengthy sporulation process, along with the time it takes for patients to get sick. By the time symptoms appear, patients may not remember what they ate two weeks earlier, where they bought it or whether it could have been the source.

Cyclospora also has been tied to herbs, such as cilantro and parsley, that are easily forgotten when patients are asked to recall their food histories.

Another challenge is timing. Contaminated produce often disappears from store shelves before health investigators can identify it. Many fruits, vegetables and herbs linked to Cyclospora have short shelf lives, meaning they are eaten or discarded before they can be tested.

Fresh produce is also widely distributed. A single shipment of contaminated herbs, leafy greens or berries may be divided among multiple distributors, grocery stores and restaurants across several states, making it even harder to trace illnesses back to one source.

The most effective way to prevent foodborne illnesses like Cyclospora is by thoroughly cooking food. However, many of the foods most commonly linked to Cyclospora outbreaks — including berries, basil, cilantro, parsley and leafy greens — are typically eaten raw.

Health experts recommend washing fresh fruits and vegetables under running water before eating, cutting or cooking them, even if they are labeled as prewashed. While washing can help remove dirt and some germs, it does not reliably remove Cyclospora if produce was contaminated earlier in the food supply chain.

Because contamination often occurs during growing, harvesting or processing, preventing Cyclospora infections also depends on safe farming, sanitation and food handling practices before produce ever reaches consumers.

Finally, pay attention to public health alerts and recalls. If health officials identify a food linked to a Cyclospora outbreak, avoid eating it and throw away any products you may have at home.

If you believe you may have Cyclospora, contact your health care provider. They can help determine whether you need treatment and order the appropriate stool test.