Ask the Experts: What you should know about cyclosporiasis

Welcome to Ask the Expert, a UTHealth Houston newsroom series in which leading physicians examine pressing health challenges. In this edition, we address the cyclosporiasis outbreak across the United States.

Since May 1, 2026, the Centers for Disease Control and Prevention has received reports of 1,645 confirmed domestic cases of cyclosporiasis and is aware of more than 5,100 cases that require further analysis to confirm the illness was domestically acquired. Catherine Troisi, PhD, a professor of epidemiology at UTHealth Houston School of Public Health, said the illness is rarely contagious and not fatal. Tomás DaVee, MD, associate professor and gastroenterologist at McGovern Medical School at UTHealth Houston, shares advice on what to do if you fall ill with the intestinal parasite. 

What is cyclosporiasis?

Cyclosporiasis is a gastrointestinal illness caused by the microscopic parasite Cyclospora. People become infected through consuming food or water contaminated with fecal matter. Although the source of the contamination is still under investigation, previous outbreaks have been linked to consuming fresh produce such as bagged or processed salad greens, basil, cilantro, parsley, raspberries, blackberries, snow peas, and sugar snap peas.

How to avoid contracting it 

The Centers for Disease Control and Prevention and the Food and Drug Administration are working with local officials to pinpoint the sources of the illness. While outbreaks are usually linked to one food source, there could be several contaminated sources.

While it’s not an option for all produce, heating fruits and vegetables to at least 158 degrees Fahrenheit will kill the parasite and make the food safe to consume. Raw produce should be washed thoroughly before eating. A little lemon juice or vinegar, or something acidic, may help to wash fruits and vegetables. When you’re preparing fruits and vegetables, cut away any damaged or bruised areas. This is not going to fully protect you, but it’s a good start.

What are the symptoms?

Symptoms take between two days and two weeks, with an average of one week, to develop. The most commonly reported symptom is cramping and bloating associated with diarrhea, loss of appetite, weight loss, nausea, and fatigue. Severe symptoms include severe dehydration, bloody stools, severe abdominal pain, persistent vomiting, abnormal kidney function or electrolyte levels, or symptoms lasting longer than about a week. However, infected individuals can also be asymptomatic.

If you are sick, you should contact your healthcare provider because the illness can be treated with antibiotics. If left untreated—particularly in the elderly, the very young, and people with immunocompromising diseases— cyclosporiasis can be quite serious.

-By Catherine Troisi, PhD, professor and infectious disease epidemiologist at UTHealth Houston School of Public Health

How to manage symptoms after diagnosis

For severe diarrhea, medical-grade oral rehydration is preferred. Anyone who cannot keep fluids down or has signs of severe dehydration may need intravenous fluids and should seek urgent medical care.

Dietary restriction is not recommended, as most people will find smaller meals easier to manage. Keep simple foods available, including rice, oatmeal, potatoes, noodles, crackers, bananas, and broth-based soups, as they tend to be most tolerable.

For mild illness without significant dehydration, drink plenty of water along with electrolyte drinks, or oral rehydration solutions. As a general rule, look for an electrolyte drink with approximately 500 to 1,000 milligrams of sodium per 16-ounce serving. A homemade salt-and-sugar solution can be used temporarily. To make it,  mix half a teaspoon of salt and six teaspoons of sugar with one liter, or just over 4 cups, of clean, boiled, or bottled water. 

Severe gut impacts of cyclosporiasis

In a severe case of cyclosporiasis, adults may develop acute gastroenteritis, which is the inflammation of the stomach and intestines. Anyone experiencing severe symptoms should focus on hydrating and eating as tolerated. Most cases improve with supportive care, but in some cases, severe symptoms—such as a fever of 101.3 degrees Fahrenheit or higher, six or more watery stools in 24 hours, a rapid heart rate, dizziness or a drop in blood pressure when standing, or an inability to keep fluids down—should prompt immediate medical evaluation. 

Prevention is key 

The fundamentals remain the most effective. Practice thorough handwashing with soap and water, keep raw meat and poultry separate from ready-to-eat foods, clean utensils and surfaces carefully, cook foods to safe internal temperatures, and refrigerate perishable foods promptly.

Perishable food should not sit at room temperature for more than two hours, or more than one hour in extreme heat. Those who are pregnant, over 65, immunocompromised, or caring for very young children should be especially cautious with pre-cut produce, deli meats, soft cheeses, and unpasteurized products.

Staying aware, cautious, and informed are the simplest ways to protect you and your family from this foodborne illness. 

-By Tomás DaVee, MD, associate professor and gastroenterologist with McGovern Medical School at UTHealth Houston

All quotes should be attributed to the respective subject matter expert. 

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