How To Tell if You Have Cyclospora: Symptoms, Warning Signs and When To See a Doctor or Go to the ER

The 2026 Cyclospora outbreak in the US has left thousands of people asking whether persistent diarrhoea or stomach problems could mean they are sick with Cyclospora. Unlike a virus such as norovirus, Cyclospora is a microscopic parasite that infects the small intestine and can cause prolonged gastrointestinal illness.

The current Cyclospora outbreak has been linked to iceberg lettuce from Taylor Farms de Mexico but further testing showed a false positive. The FDA issued an apology to Taylor Farms over the initial false positive announcement.

What Does a Cyclospora Infection Feel Like?

The first warning sign is often watery diarrhoea, which can be frequent and sometimes explosive. Other common symptoms include loss of appetite, weight loss, stomach cramps, bloating, increased gas, nausea and fatigue. Less common symptoms can include vomiting, body aches, headache and a low-grade fever.

One reason Cyclospora can be difficult to recognise is its delayed onset. Symptoms typically begin about one week after infection, although they can appear as soon as two days or more than two weeks after exposure. Some infected people may have no symptoms at all.

The illness can also behave differently from ordinary short-lived food poisoning. Without treatment, symptoms may continue for a month or longer and can disappear before returning. Fatigue may persist even after the gastrointestinal symptoms improve.

How Do You Know if You Are Sick With Cyclospora?

Symptoms alone cannot confirm Cyclospora. The parasite is diagnosed through laboratory testing of a stool sample, but routine stool testing does not always include Cyclospora.

Healthcare providers may therefore need to specifically request testing when the parasite is suspected. In some cases, several stool samples collected on different days may be necessary because the parasite can be shed intermittently.

People should tell their healthcare provider if they have experienced prolonged watery diarrhoea and recently ate foods associated with an outbreak, travelled to an area where Cyclospora is common, or consumed potentially contaminated food or water.

Cyclospora infections occur when someone swallows the parasite, usually through contaminated food or water. In the US, Cyclospora outbreaks have frequently been associated with fresh produce.

The parasite's life cycle also means direct person-to-person transmission is considered unlikely because organisms passed in stool generally need time in the environment before becoming infectious.

When Should You Call a Doctor or Visit the ER?

Anyone developing symptoms consistent with cyclosporiasis should contact a healthcare provider, particularly when diarrhoea persists. Early medical advice is important because the infection can be specifically tested for and treated.

The CDC lists trimethoprim-sulfamethoxazole as the treatment of choice for cyclosporiasis. Patients should not self-medicate with antibiotics.

Seek urgent medical attention for signs of significant dehydration, including very little or no urine, a very dry mouth or throat, severe dizziness or difficulty keeping fluids down.

CDC guidance for diarrhoeal illness also recommends medical evaluation for bloody stools, a fever above 102°F (38.9°C), prolonged vomiting or diarrhoea lasting more than three days.

For severe dehydration, confusion, fainting, extreme weakness or an inability to keep fluids down, emergency medical care may be necessary.

The key message is that Cyclospora infections can look like ordinary stomach illness at first. Persistent watery diarrhoea after a potential food exposure should not simply be ignored.

During the 2026 Cyclospora outbreak, recognising the pattern and telling a doctor about possible exposure can help patients receive appropriate testing while helping public-health officials identify additional cases.