What is cyclosporiasis? | Explained

The story so far:

A widespread outbreak of a gastrointestinal illness has been reported in the United States. The infection, cyclosporiasis, caused by the Cyclospora parasite, occurs when people consume or water that contains the parasite. According to the U.S. Centers for Disease Control and Prevention (CDC), in a health advisory issued on July 14, 2026, it has received reports of 1,645 confirmed domestic cases of cyclosporiasis since May 1 and is aware of 5,100 cases that require further analysis to confirm the illness, from 34 states, substantially higher than the 249 cases reported in the country by this same time last year. Case counts typically rise during spring and summer months, and CDC considers May 1-August 31 the annual cyclosporiasis season. Because cyclosporiasis is often underdiagnosed and underreported, the true number of illnesses is likely higher than what has been reported, it noted. At present, a specific food item has not yet been confirmed as the source.

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What is cyclosporiasis?

Cyclosporiasis is a type of food poisoning caused by the microscopic parasite, Cyclospora cayetanensis. It spreads through the faeco-oral route, which means that food or water contaminated by faeces containing the parasite causes the illness. It does not spread from person to person.

While it is usually not life-threatening, symptoms can range from mild to severe and may last anywhere between a few days to over a month. Symptoms usually begin about a week after exposure. The main symptom is frequent, explosive, watery diarrhoea. Other symptoms include bloating, loss of appetite, stomach cramps, fatigue and even weight loss. Sometimes vomiting and low-grade fever may be experienced.

Anyone can contract the infection. In children, the elderly and those with weak immune symptoms, the infection may be severe. Untreated, the symptoms can last for a long time, and patients can relapse as well. Complications can include severe dehydration, malabsorption (a digestive disorder where your intestine is unable to absorb nutrients), cholecystitis (inflammation of the gall bladder) and reactive arthritis (joint inflammation).

Testing and treatment

Testing for cyclosporiasis is challenging because the parasite might not shed enough to be detected in one stool sample, and it is not part of routine stool testing. This means that patients may have to provide more than one sample over several days for an accurate diagnosis. The CDC noted that clinicians should specifically request diagnostic testing for Cyclospora when it is clinically suspected. Stool PCR tests to identify the parasite’s DNA and stool microscopy that identifies the parasite’s eggs can diagnose the condition.

As far as treatment goes, the CDC recommends treating confirmed cases of cyclosporiasis with 7-10 days of trimethoprim-sulfamethoxazole (TMP-SMX) for adults and children aged over two months. Longer courses may be considered for patients with immunocompromising conditions. Hydration is also recommended.

With proper diagnosis and treatment, most patients feel better, but occasional bouts of diarrhoea may continue for some time. While the infection may go away on its own without treatment, it can put patients at risk of complications, and the CDC recommends visiting a clinician if you have prolonged or watery diarrhea, especially if it lasts more than a few days.

So far, according to the CDC, of the 1,645 case-patients whose information is available, 141 (9%) were hospitalised. No deaths have been reported.

Sources of contamination and prevention

This is not the first cyclosporiasis outbreak in the U.S.; there have been outbreaks in previous years as well.

Previous outbreaks have been linked to consuming contaminated fresh produce. News reports from the U.S. this year have indicated that it may be the case again. In Michigan, one of the hardest-hit States, health officials flagged lettuce and salad greens as a potential source. On Tuesday (July 14), fast food chain Taco Bell announced in the U.S. that it has voluntarily, temporarily removed some ingredients at select restaurants as a precautionary measure.

Fruits and vegetables tied to cyclosporiasis outbreaks include: leafy greens, lettuce, spinach, basil, cilantro and parsley as well as other produce such as raspberries and snow peas.

The CDC recommends reducing risk by thoroughly washing fresh produce under clean running water before eating and by following safe food handling practices. It states that consumers must be aware that chemically disinfecting or sanitising produce might not fully eliminate Cyclospora. It is important to thoroughly wash produce even if it is labeled as pre-washed. The U.S. Food and Drug Administration (FDA) recommends washing hands with warm water and soap for at least 20 seconds before and after handling food as well as washing and sanitising the insides of refrigerators, countertops and chopping boards.