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WA cyclosporiasis cases: What we know about the parasite
A parasite causing explosive diarrhea is spreading across the country and has made its way to Washington state. Here is what we know about the latest cases.
SEATTLE - The Washington State Department of Health (DOH) says the state is not experiencing an outbreak of cyclosporiasis, despite a major surge in the foodborne parasitic illness across the United States. Health officials confirmed that none of Washington's 27 reported cases of the stomach illness are linked to active outbreaks in 34 other states.
Cyclosporiasis parasite (CDC) (Centers for Disease Control and Prevention)
Cyclosporiasis in Washington
Since May 1, 2026, Washington has recorded 27 confirmed cases of cyclosporiasis. Seattle-based food safety attorney Bill Marler of the Marler Clark law firm said the state's case numbers are currently in line with historical summer averages.
What they're saying:
"We're about on track of what we would normally see," Marler said. "It is possible the citizens of Washington are dodging this outbreak that's hitting the Midwest."
Marler noted that the lack of local connection to the national spike may simply come down to chance. "Sometimes it's the luck of the draw, and it looks like at this point, Washington state citizens have sort of dodged it," he said.
Washington typically records only zero to 11 cases of cyclosporiasis annually, which generally occurs after international travel. The DOH reported the travel status of Washington's 27 cases this year, which included 22 individuals who recently traveled internationally, three cases where the illness was likely acquired domestically and two cases whose travel history is unknown.
While Marler praised state and local officials for doing a good job of tracking cases in Washington, he expects the total number of cases across the country to keep rising.
By the numbers:
The Centers for Disease Control and Prevention (CDC) is aware that states are likely to report higher case counts of cyclosporiasis than reflected in CDC data, and it is working closely with states to update numbers as additional cases are confirmed.
Cyclosporiasis outbreak in the United States
Big picture view:
Since May 1, 2026, the CDC 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 as domestically acquired cyclosporiasis. So far this year, multiple states have reported an increase in cases compared to the same period in 2025.
The national outbreak has resulted in 141 hospitalizations and zero deaths. In the hardest-hit area, the Midwest, Michigan Health and Human Services reported 2,640 cases.
Public health officials do not yet know the specific food source or produce item causing the multi-state clusters. However, authorities are currently investigating produce used by Taco Bell as a possible source of the outbreak.
Marler says it's frustrating that a specific food source has not yet been identified to halt the spread. He also worries that cuts at the CDC and FDA are affecting how the agencies monitor foodborne illnesses. It's causing additional stress on the system and impacting the size as well as the speed of these outbreaks.
What is Cyclosporiasis?
Cyclosporiasis is an intestinal illness caused by a microscopic parasite. The typical season for this illness runs from May 1 through August 31, and case counts regularly rise during the spring and summer months.
Cyclosporiasis symptoms
Why you should care:
The parasite causes symptoms that include persistent, watery diarrhea (which can last longer for individuals with weakened immune systems), nausea and abdominal pain, lack of appetite, weight loss, and fatigue.
National case counts are expected to grow because there is a routine six-week delay between when a person gets sick and when the case is officially reported. Many people with mild symptoms do not seek treatment, meaning the actual number of cases is likely much higher.
Consumers can lower their risk of getting sick by thoroughly washing all fresh fruits and vegetables before eating them. Those planning to travel to areas where the parasite is common should consult a travel clinic or review the CDC Travelers’ Health website.
What you can do:
Medical professionals advise anyone experiencing these symptoms to see a healthcare provider. If the illness is confirmed, specific antibiotics are available for treatment.
The Source: Information in this story comes from original reporting by FOX 13 Seattle, the Washington State Department of Health, and an interview with Seattle-based food safety attorney Bill Marler of the Marler Clark law firm.
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