Federal health officials are tracking a large multistate outbreak of cyclosporiasis, a gastrointestinal illness caused by the microscopic parasite Cyclospora, and have not yet identified the food source responsible. As of July 13, 2026, the Centers for Disease Control and Prevention has confirmed more than 400 people infected across four states, with investigators still working to pinpoint the contaminated food item.
What Cyclosporiasis Is and How It Spreads
Cyclosporiasis is an intestinal infection caused by the parasite Cyclospora cayetanensis. The parasite is typically found on contaminated fresh produce and is ingested when a person eats or drinks something that has come into contact with it. Unlike bacteria that can contaminate produce through casual environmental contact and can be removed or reduced through rinsing, Cyclospora requires specific conditions related to fecal contamination of water or soil that comes into contact with crops, often in the fields where produce is grown or processed. That upstream origin makes it difficult for individual consumers to detect or eliminate the risk at the point of consumption.
Symptoms usually begin about one week after exposure, a delay that makes it harder for both patients and investigators to connect illness to a specific food. Early symptoms include watery diarrhea, nausea, loss of appetite, abdominal cramping, fatigue, and weight loss. Unlike many foodborne illnesses that resolve within a few days, cyclosporiasis can last for weeks if untreated, and some people experience repeated cycles of improvement followed by relapse before fully recovering. That relapsing pattern is one of the distinguishing clinical features of the infection and can lead patients and providers to overlook a parasitic cause if they are not specifically looking for it.
Crucially, washing produce does not destroy Cyclospora. The parasite is resistant to the kind of surface rinsing that eliminates many bacterial contaminants like Salmonella or E. coli. Only cooking produce to at least 158 degrees Fahrenheit reliably kills the parasite. That threshold is lower than most standard cooking temperatures for meat or poultry, so any produce that is heated through in a pan or oven should reach it without difficulty. The challenge is that many of the produce items most commonly linked to past Cyclospora outbreaks, including fresh salad greens, herbs, and berries, are foods that most people eat raw, making the cooking option impractical in everyday use.
The Current Outbreak: What Is Known
The Centers for Disease Control and Prevention has confirmed active outbreak cases in Michigan, Ohio, West Virginia, and Kentucky, with sick people reporting symptoms on or after June 22, 2026. CDC is also aware of additional cases under investigation that may expand the geographic footprint of the outbreak as testing results come in. The total number of cyclosporiasis cases in the United States since May 1, 2026, including cases acquired both inside and outside the current outbreak cluster, is 1,645 according to CDC surveillance data. The actual number of people sick is almost certainly higher, because many people recover without seeking medical care and are never tested for Cyclospora specifically.
No specific food item has been confirmed as the source as of this reporting. Public health investigators are interviewing people linked to the outbreak to identify common foods eaten before illness began, a process that requires collecting detailed dietary histories from dozens or hundreds of patients and then using statistical analysis to identify which foods appear more frequently among sick people than would be expected by chance. That process takes time, particularly when the implicated food may have already been consumed and disposed of before investigators can collect samples for laboratory testing.
Past outbreaks of cyclosporiasis in the United States have been traced to fresh produce items including bagged salad kits, fresh basil, snow peas, raspberries, and cilantro. Several of those past outbreaks involved produce imported from Mexico or Central America, where growing conditions and agricultural water sources may increase the risk of Cyclospora contamination. The current outbreak's geographic concentration in the Midwest may reflect regional distribution patterns for a specific product, but that determination has not yet been made, and the outbreak source investigation remains ongoing.
What Washington State Health Officials Are Advising
The Washington State Department of Health advises thorough handwashing when preparing, cooking, and eating produce. While washing alone will not destroy the Cyclospora parasite, it remains an important practice for overall food safety and helps reduce risks from other pathogens that may be present alongside or independent of the current outbreak. Until the outbreak source is identified, the department advises people at increased risk of serious illness to consider avoiding certain higher-risk produce categories.
Items to approach with caution until the source is identified include bagged salad kits, lettuce, berries such as strawberries and raspberries, and leafy herbs including cilantro and parsley. People at higher risk include older adults, individuals with weakened immune systems due to conditions like HIV, cancer treatment, or organ transplantation, and those on medications that reduce immune function such as corticosteroids or immunosuppressants. For these groups, even a relatively low exposure to the parasite can produce more severe or prolonged illness than it would in a healthy adult.
Safer alternatives during the outbreak investigation include fruits and vegetables where you can remove an outer layer before eating, such as citrus, bananas, melons, or avocados, which present less risk because the edible portion is protected. Canned or frozen versions of commonly affected produce items are also lower risk because the processing involved either eliminates or inactivates potential parasites. Cooking produce items rather than eating them raw remains the most reliable protective measure, and the 158-degree cooking threshold is lower than most standard cooking temperatures, so anything heated through in a pan, oven, or steamer should be adequate to destroy the parasite if it is present.
What to Do If You Feel Sick
People who develop watery diarrhea, fatigue, and loss of appetite, particularly if they have recently eaten fresh produce, should contact their healthcare provider. Cyclosporiasis is treated with a combination antibiotic called trimethoprim-sulfamethoxazole, and most people improve within a few days of starting treatment. Without treatment, symptoms can persist or recur for weeks, and the relapsing pattern of the illness can be mistaken for irritable bowel syndrome or other functional gastrointestinal conditions, leading to delays in appropriate treatment.
Testing for Cyclospora requires a specific stool test that is not part of standard panels used to investigate diarrheal illness. Many providers order routine bacterial stool cultures when a patient presents with diarrhea, and those cultures will not detect Cyclospora. Telling your provider that you are concerned about a foodborne illness and that you want to be tested for parasites specifically, and mentioning cyclosporiasis by name if you are aware of the current outbreak, will help ensure the right test is ordered and that treatment is not delayed while waiting for results that will inevitably be negative if the wrong test is used.
Residents who believe they may be part of this outbreak, particularly those who have traveled recently to the affected states of Michigan, Ohio, West Virginia, or Kentucky, or who have eaten produce that may have been distributed nationally from a common source, can report their illness to the Washington State Department of Health or to Whatcom County Health and Community Services. Reporting helps public health investigators identify the common source more quickly by adding data points to the outbreak investigation, and a faster source identification shortens the overall duration of the outbreak for everyone who might otherwise be exposed through continued distribution of a contaminated product.
